MOF-based electrode materials for aqueous zinc-ion batteries: design strategy and future challenges

Abstract

Rechargeable aqueous zinc-ion batteries (AZIBs) are considered the most promising energy storage devices due to their high theoretical specific capacity, safety, and low cost. Metal–organic frameworks are emerging porous materials characterized by adjustable structures and active metal centers. This review summarizes the application of MOFs in the preparation of electrodes for AZIBs, particularly focusing on various design strategies. Moreover, we provide electrochemical performance comparisons under different strategies and propose future development challenges.

---

10th anniversary statement

It's a true honor to be invited as an author for the 10th anniversary of Inorganic Chemistry Frontiers; as a highly influential, forward-thinking journal, our group has published over ten groundbreaking papers on this platform. We focus on potential metal–organic frameworks (MOFs), employing engineering approaches for altering their morphologies and properties, and have widely applied these materials in energy storage fields such as supercapacitors and Li–S batteries. We also investigate the role played by heteroatom doping in improving their OER catalytic performance. These pioneering results have proved their practical value and sparked extensive discussions. Looking ahead, we hope Inorganic Chemistry Frontiers will continue to lead the way in inorganic chemistry, providing a high-quality, open platform for researchers around the world.

Introduction

With the depletion of traditional fossil fuels and increasingly serious environmental problems (climate change and greenhouse gas emissions), the development of renewable energy has become an urgent issue to maintain the sustainable and stable development of human society.^1–5 Green renewable energy includes hydropower, wind energy, solar energy, etc., and the secondary energy electricity converted from this will help achieve the goals of “carbon peak” and “carbon neutrality”. However, these natural energy sources are often limited by geographical and time conditions, making it difficult to achieve continuous and stable power generation.^6–9 As a result, energy storage technology has only been extensively studied by scientists for decades as a necessary technical support for the full development of renewable energy. Typical energy storage devices include lead-acid batteries,¹⁰ lithium-ion batteries,¹¹ supercapacitors,¹² and fuel cells.¹³ It is worth noting that lead-acid batteries suffer from bulkiness, low energy density, and their low cycling performance and heavy metal electrolytes limit their practical applications in high-tech fields.¹⁴ Lithium-ion batteries, known for their high energy density, are widely used in electric vehicles and electronic gadgets. However, their widespread adoption is hindered by the scarcity of lithium resources, the flammability of organic electrolytes, and high production expenses.^15–17

Rechargeable batteries stand as a promising energy storage technology, utilizing the reversible electrochemical incorporation of cations into host materials for remarkable cycling durability.¹⁸ Among these, calcium, aluminum, zinc, and other multivalent metal-ion rechargeable batteries have garnered significant attention because of their high energy density, cost-effectiveness, and the abundance of their constituent resources.^19,20 Among these, rechargeable aqueous zinc-ion batteries (AZIBs) stand out, benefiting from their impressive theoretical capacity of 820 mA h g⁻¹, derived from two-electron redox chemistry. They further benefit from a low redox potential (−0.76 V vs. SHE), high overpotential for hydrogen evolution, abundant natural reserves of zinc, and environmental non-toxicity, making them a compelling choice for sustainable energy storage solutions.^21–23 Compared with traditional organic electrolytes, aqueous electrolytes offer several advantages, including enhanced safety, superior cost-effectiveness, high ionic mobility, and excellent ionic conductivity (Fig. 1a). Due to the above advantages, AZIBs have great potential for energy storage, and many results have been achieved in recent years (Fig. 1b). Through pouch cell technology, AZIBs can be applied in wearable flexible energy storage devices.

Fig. 1 (a) Schematic illustration of the advantages of AZIBs. (b) Studies based on AZIBs in recent years with challenges of anode and cathode materials development. (c) The outstanding achievements of anode and cathode materials design strategies.^40–47

The anode of AZIBs is a zinc foil, with a simple reversible redox reaction mechanism of Zn – 2e⁻¹ ↔ Zn²⁺. Cathode materials are typically V-based materials, Mn-based materials, and Prussian blue and its analogues. During cycling, redox reactions involving V⁵⁺/V⁴⁺/V³⁺, Mn⁴⁺/Mn³⁺/Mn²⁺, and Fe³⁺/Fe²⁺ are involved to facilitate Zn²⁺ insertion/extraction. In mildly acidic environments, co-insertion/extraction of Zn²⁺/H⁺ has also been identified as a feasible mechanism.^24–26 Sun et al. analyzed the GITT curves based on electro-deposited e-MnO₂ and found that the slight variation in voltage and rapid ion diffusion in the region I indicates H⁺ insertion.²⁷ To achieve large-scale commercial application of rechargeable AZIBs based on the reversible insertion/extraction of Zn²⁺, the following challenges need to be addressed: (1) the intense electrostatic interaction between the cathode material and Zn²⁺ leads to structural collapse, material dissolution during charging and discharging, and low electronic conductivity; (2) uncontrolled dendrite growth, hydrogen evolution reaction (HER), and zinc corrosion at the anode.^28–31 Vanadium-based oxides such as VO₂ and V₂O₃ have typical tunnel structures, while V₂O₅ has a typical layered structure, providing space for the reversible insertion/extraction of Zn²⁺. Manganese exhibits multiple oxidation states, and studies have demonstrated the H⁺/Zn²⁺ insertion/extraction mechanism when it is used as cathode material. Generally, V-based cathodes have high capacity while their operating voltage remains relatively low, resulting in low energy density; Mn-based cathodes have considerable theoretical capacity and high operating voltage but low ionic and electronic conductivity, leading to poor cycling performance. Although Prussian blue and its analogues possess an open three-dimensional framework, defect structures often lead to side reactions and structural collapse.^32–34 Strategies for constructing protective layers, electrolyte additives, and solid electrolytes are currently the main methods to address anode challenges. Among them, the protective layer strategy prevents direct contact between the Zn foil and the aqueous electrolyte, optimizing the electrode–electrolyte interface to avoid HER and Zn corrosion. Moreover, the protective layer strategy is technologically mature, offers high economic benefits, and can be adapted for large-scale production, thus becoming the most promising method.^35–37 However, zinc transfer at the cathode and dendrite growth at the anode can lead to significant performance degradation, structural collapse, and even penetration of the separator causing short circuits after a limited number of cycles, presenting challenges in identifying materials with features of high porosity and stable structure to support the reversible insertion/extraction of Zn²⁺.^38,39

Metal–organic frameworks (MOFs) are coordination networks formed by linking metal ions or clusters with organic ligands, boasting high surface area, high porosity, adjustable structures, and abundant redox-active centers among their many benefits.^48,49 MOFs have a great range of application scenarios, including energy storage,⁵⁰ gas transport,⁵¹ catalysis,⁵² and sensing.⁵³ MOFs’ open framework structure offers active sites conducive to storing alkali metal ions, while simultaneously addressing volume fluctuations during charging and discharging processes. Furthermore, their porous architecture and abundant channels enhance the transport of reactants and electrons. Currently, many studies have applied MOF materials in the preparation of alkaline battery electrode materials, demonstrating good performance.^54–57 Furthermore, MOF precursors with regular structures can maintain their original structure after calcination to obtain C-doped materials that enhance conductivity. Based on this, the application of MOFs in AZIB anodes can serve as precursors for obtaining vanadium-based oxides and manganese-based oxides, and can also act as cathode protective layers to regulate zinc deposition and avoid the formation of zinc dendrites.^58–60 Some studies have summarized the mechanisms and electrode design strategies of AZIBs (Fig. 1c). In this review, we pay attention to the latest progress in constructing AZIB anodes using MOFs, while highlighting the design of cathodes with MOF protective layers to guide uniform zinc deposition. We hope our work can provide guidance for future research.

Cathodes for AZIBs

To achieve reversible insertion/removal of Zn²⁺, V-MOF and Mn-MOF with typical layered and tunnel structures, and Prussian blue and its analogues have been shown to be potential cathode materials. To further optimize the kinetics to achieve Zn²⁺ desolvation and improve structural stability, metal ions and conductive organic compounds can be intercalated by compounding with carbon-based materials.^61–63

Vanadium-based MOFs

V-MOFs have garnered significant attention due to their high theoretical capacity (820 mA h g⁻¹), multiple oxidation states (V²⁺ to V⁵⁺), and excellent rate performance.^64–66 The oxides derived from V-MOFs, such as VO₂ and V₂O₃, possess typical 1D tunnel structures, while V₂O₅ has a typical layered structure (Fig. 2c), which supports the efficient reversible insertion/extraction of Zn²⁺. Through rational design, 3D porous structures can also be obtained, demonstrating superior electrochemical performance.^67–69 However, V-MOFs and their derivatives typically suffer from low conductivity. Combining them with other materials, including carbon materials, metal ions, and conductive polymers, can effectively improve conductivity while expanding the interlayer spacing, thus accelerating the reversible insertion/extraction of Zn²⁺ (Fig. 2a). Table 1 shows a comparison of the electrochemical performance of V-MOFs with various design strategies.

Fig. 2 (a) Schematic illustration of V-MOF derivatives combined with different materials and the advantages they share. V-MOFs and their derivatives of different dimensions, (b) 1D diamond-shaped channels V-MOF (MIL-47),⁷⁰ (c) 2D laminar structure of V₂O₅, and (d) 3D highly porous V-MOF (MIL-100).⁷¹

Table 1 Electrochemical performance summary of some typical V-MOF and their derivative-based AZIB cathode materials

Design strategy	Electrode material	Voltage window (V)	Initial capacitance	Current density	Cycling stability (retention/cycles/current density)	Ref.
Pristine MOF	1D V-MOF (MIL-47)	0.4–1.4	320 mA h g^−1	0.1 A g^−1	72.8%/70/0.5 A g^−1	70
	3D MIL-100 (V)	0.2–1.6	362 mA h g^−1	0.2 A g^−1	95.45%/3500/5 A g^−1	71
MOF derivative	Core–shell V2O5	0.4–1.4	309.4 mA h g^−1	0.1 A g^−1	91.4%/4000/3 A g^−1	78
	V2O5 microspheres	0.2–1.6	449 mA h g^−1	0.5 A g^−1	44.5%/1400/0.5 A g^−1	79
MOF derivative/carbon materials	a-V2O5@C	0.2–1.8	620.2 mA h g^−1	0.2 A g^−1	91.4%/20 000/40 A g^−1	81
	p-V2O3/VN@C	0.2–1.8	518 mA h g^−1	0.2 A g^−1	80.9%/2000/10 A g^−1	67
	MIL-88B(V)@rGO	0.2–1.6	479.6 mA h g^−1	0.05 A g^−1	80.3%/400/2 A g^−1	46
	VN/N-CNFs	0.3–1.9	710 mA h g^−1	0.5 A g^−1	482 mA h g^−1/30 000/50 A g^−1	82
MOF derivative/metal ions	Cu-Fe2VO4	0.2–1.6	237 mA h g^−1	0.3 A g^−1	75%/8000/1 A g^−1	83
	ZnVOx	0.2–1.6	526.6 mA h g^−1	0.2 A g^−1	84%/7000/10 A g^−1	84
	CoVOx	0.2–2.0	288.2 mA h g^−1	0.05 A g^−1	94%/1000/1 A g^−1	85
	FeVOx	0.2–1.6	325 mA h g^−1	0.05 A g^−1	94.8%/4000/1 A g^−1	86
MOF derivative/conductive polymers	PANI80-V2O5	0.3–1.6	268.8 mA h g^−1	10 A g^−1	97.77%/3000/10 A g^−1	87
	PVO@PEDOT	0.2–1.6	370 mA h g^−1	1 A g^−1	92.8%/3000/10 A g^−1	88
	PANI-V2O5	0.2–1.6	291 mA h g^−1	8 A g^−1	91.8%/2000/8 A g^−1	89

---

Pristine V-MOFs and their derivatives

Although the operating voltage is relatively low, V-MOFs can be designed to form materials of different dimensions, thereby enhancing their electrochemical performance.^72–74 For example, Pang's team synthesized one-dimensional layered nanorod MOFs (V-MOF, MIL-47) via a facile one-pot hydrothermal strategy. The resulting material had a rhombic structure with numerous empty channels, which facilitated the unhindered intercalation of guest ions into the structure and their subsequent extraction (Fig. 2b).⁷⁰ Due to the inherent low conductivity of MOFs, using them directly as binder-free electrode materials presents challenges. To address this, He et al. employed a self-sacrificial synthesis strategy to create a 3D conductive MIL-47 nanowire array on carbon nanotube fibers. Through a simple one-step hydrothermal synthesis and careful adjustment of reaction time, 3D V-MOFs were converted into numerous nanowire units aligned along specific crystal planes via Ostwald ripening and a self-assembly process, with the V-MOFs acting as a self-sacrificial template. The obtained V-MOF||Zn battery demonstrated volumetric capacity of 101.8 mA h cm⁻³ and great rate performance in aqueous electrolyte.⁷³ Considering the dissolution of cathode materials during long cycling, Mondal et al. selected V-MOF (MIL-100) due to its strong V–O bonds, which can effectively inhibit dissolution. The 3D highly porous MIL-100 (V) MOF, synthesized via solvothermal method, facilitated the efficient insertion and extraction of guest Zn²⁺, while exhibiting a peak capacity of approximately 362 mA h g⁻¹, maintaining around 95.45% of its initial capacitance after 3500 continuous cycles (Fig. 2d).⁷¹

The V₂O₅ cathode material derived from the calcination of V-MOFs exhibits multiple valence states (+2, +3, +4, +5) and an open-framework crystal structure that accelerates the reversible insertion/extraction of Zn²⁺, along with a high theoretical capacity. However, its unstable layered structure and low conductivity severely limit its electrochemical performance.^75,76 Developing and synthesizing materials with stable nanostructures and reduced ion/electron transport distances are essential strategies for addressing the challenges associated with V-based materials.⁷⁷ Hao et al. synthesized a vanadium oxide precursor with a self-grown core–shell structure in one step using V-MOF. During the reaction process, the precursor underwent Ostwald ripening, with the structural transformation sequence being microspheres → core–shell → yolk–shell. The ARZIBs assembled with core–shell V₂O₅ cathodes delivered a capacity of 309.4 mA h g⁻¹.⁷⁸ Yu et al. constructed 3D porous V₂O₅ through a simple calcination process using spherical V-MOFs. The resulting V₂O₅ exhibited mixed valence states, significantly reducing polarization, and its 3D porous structure enhanced ion reaction kinetics.⁷⁹ In another study, Zhou et al. prepared rod-shaped anhydrous vanadium pentoxide through the pyrolysis of MIL-47. This material, composed of small nanosheets, exhibited a larger specific surface area.⁸⁰

V-MOF derivatives/carbon materials composites

V-based oxides typically exhibit poor conductivity, but the introduction of carbon layers can enhance conductivity while protecting V-MOFs from hydrolysis and improving mechanical stability.^90–93 Common methods for introducing carbon layers include mixing V-MOF with a carbon source followed by high-temperature pyrolysis or carbonization, as well as chemical vapor deposition. Tunnel-like or layered V-based oxides are often employed as cathode materials for AZIBs. Among them, VO₂ has a typical tunnel structure, while V₂O₅ has a layered structure.^94–96 Despite the lattice stability of VO₂ during Zn²⁺ insertion/extraction, its narrow potential window and low capacity limit its application. V₂O₅ has suitable reaction sites, but its structural collapse during long cycling significantly restricts its practical use. Tong et al. used vanadium-based MOF (V-MIL-88) in a porous carbon framework and a heterojunction structure of vanadium oxide (C@VO₂@V₂O₅) through carbonization and subsequent oxidation (Fig. 3a). This distinctive heterostructure offered more reaction sites, reduced transport distances, and demonstrated outstanding cycling stability, maintaining 90.3% of its capacity after 2000 cycles at 5 A g⁻¹. Additionally, it achieved a high specific capacity of 376 mA h g⁻¹ at 50 mA g⁻¹.⁹⁷ However, the interaction between conventional V-based oxides and carbon materials is often restricted to mere physical contact, which restricts the rapid electron transfer and thus reduces the rate performance. Additionally, Zn²⁺ insertion/extraction often exhibits slow kinetics and the formation of irreversible phases within the crystal structure, limiting the electrochemical performance. Deng et al. prepared an amorphous vanadium pentoxide and conductive carbon composite (a-V₂O₅@C) by in situ electrochemical induction of MIL-88B(V)-derived crystalline V₂O₃ and carbon. Benefiting from the more isotropic ion diffusion paths and numerous vacancy sites in the amorphous material, the resulting composite exhibited more active sites and high conductivity. First-principles calculations show that crystalline V₂O₅ has a higher insertion energy for Zn²⁺ than amorphous V₂O₅, while amorphous V₂O₅ exhibits faster Zn²⁺ diffusion kinetics (Fig. 3b).⁹⁸ Yin et al. prepared a hierarchical porous V₂O₅ nano-bulk (p-V₂O₅) by carbonizing V-MIL-47 at 400 °C. The resulting material demonstrated superior specific capacity of 115 mA h g⁻¹ at 3 A g⁻¹, benefiting from its layered mesopores and expansive specific surface area. Subsequent cycling tests confirmed that the energy storage mechanism involved the reversible insertion and extraction of Zn²⁺ in the open-structured obtained materials.⁷² Similarly, He et al. used MIL-47(V) as a precursor and synthesized micro-rectangular V₂O_5−x@CCSMs with oxygen vacancies and a carbon coating through a two-step high-temperature carbonization process (Fig. 3c).⁹⁹

Fig. 3 (a) Schematic illustration of the synthesis process of C@VO₂@V₂O₅.⁹⁷ (b) Illustration of Zn²⁺ diffusion and Zn²⁺ insertion/extraction energy in crystalline and amorphous V₂O₅ from first-principles calculations.⁹⁸ (c) Illustration of V₂O₅@carbon core–shell microcuboids.⁹⁹ (d) Illustration of V₂O₃@graphene.¹⁰² (e) The calculated Zn²⁺ adsorption energy.⁴⁶ (f) Illustration of the synthesis process of 3D V-MOF self-derived V₂O₅@C NBAs/CNTF binder-free electrode.¹⁰³ (g) Illustration of the significant electrochemical transformation during the discharge/charge process.⁸²

Graphene, as a carbon material with ultra-high ion and electron conductivity along with high specific surface area, is often employed to enhance the conductivity of V-based oxides. The conductive graphene network enhances ion transfer and helps prevent the aggregation of active material particles.^100,101 Zhang et al. combined V₂O₃, which is derived from V-MOF and has a three-dimensional tunnel structure, with graphene. They prepared V₂O₃@graphene via a hydrothermal method, resulting in a material with a large specific surface area and layered porous structure (Fig. 3d). The powerful synergistic interaction between V₂O₃ and graphene significantly reduced structural degradation during Zn²⁺ insertion/extraction, delivering excellent reversible capacity of 450 mA h g⁻¹ at 0.1 A g⁻¹.¹⁰² Jia et al. utilized a straightforward hydrothermal method to anchor MIL-88B(V) nanorods onto reduced graphene oxide (rGO) sheets. Graphene oxide (GO) guided the formation of small-sized MIL-88B(V) nanorods. Upon initial charging, the MIL-88B(V) cathode underwent electrochemical oxidation, transforming into amorphous V₂O₅, which then facilitated Zn²⁺ insertion and extraction as the active site. Theoretical calculations showed that reduced graphene oxide sheets provided two functions: enhancing conductivity and facilitating Zn²⁺ adsorption while lowering the Zn²⁺ migration energy barrier (Fig. 3e).⁴⁶

Designing independent cathodes is another effective method in structural engineering to improve the electrochemical performance of AZIBs. Conductive carbon nanotube fibers (CNTFs) possess advantages of light weight, ultra-flexibility, and high mechanical strength. As a substrate material for AZIB electrodes, they can be applied to safe and flexible wearable electronic devices.^104,105 Kong et al. used CNTFs as a conductive flexible substrate to directly grow 3D V₂O₅@C nanowire-bundle arrays on them (Fig. 3f). Benefiting from its binder-free nature and high specific surface area structural features, the as-assembled fiber-shaped aqueous rechargeable ZIBs exhibited a high capacity of 0.71 mA h cm⁻².¹⁰³ Electrospinning, as a popular technique for constructing 3D scaffolds without current collectors and binders, can impart flexibility and conductivity to electrodes. Vanadium nitride (VN) can reach a double-electron reduction, with a theoretical capacity of 825 mA h g⁻¹, surpassing most V-based oxides, but it is limited by its cycling instability. Zhang et al. developed 3D self-supported VN-embedded N-doped carbon nanofiber (VN/N-CNFs) composites with a hierarchical structure, where VN nanoparticles derived from V-MOF were uniformly distributed in the main nanofibers and branched nanowhiskers. The important electrochemical transformation during the discharge/charge process is shown in Fig. 3g. This structure prevents the aggregation of VN particles, while the conductive encapsulation prevents direct contact with the aqueous electrolyte. The AZIBs constructed using this material demonstrated an exceptionally long cycle lifespan and maintained a reversible capacity of 482 mA h g⁻¹ after 30 000 cycles.⁸² Liu et al. synthesized V-MOF@CNT-derived V₂O₅@CNT with a nanorod structure via a hydrothermal method. Due to the synergistic effect between V₂O₅ and CNT, the resulting material delivered a high discharge capacity of 400 mA h g⁻¹ at 1 A g⁻¹, which is twice that of pure vanadium pentoxide.¹⁰⁶

Carbon coatings, graphene, and carbon fibers, as representative carbon materials, have been combined with V-MOF derivatives to prepare AZIB cathode materials, significantly enhancing conductivity to varying extents.^107–109 We recommend employing in situ growth for carbon coatings, as this approach helps avoid the decrease in conductivity due to the loose structure at the interface between the carbon coating and the material surface. Although graphene offers distinct advantages in mechanical strength and high specific surface area, its high cost and safety concerns in high-temperature or cutting environments limit its practical applications. Carbon nanofibers, however, meet the demands of flexible energy storage and have broad development prospects. Furthermore, the carbon encapsulation of VN provides long-cycle stability, presenting new avenues for future development.

V-MOF derivatives/metal ions

Interlayer insertion, as an important method to improve the conductivity and cycling stability of V-based materials, can expand the interlayer of V₂O₅, facilitating Zn²⁺ insertion and improving the overall structural stability of the material, ultimately achieving excellent rate and cycling performance.^110–112 Researchers have demonstrated that the insertion of metal elements such as Mg²⁺, Al³⁺, Cu²⁺, Zn²⁺, and Fe²⁺ can accelerate the diffusion of Zn²⁺, thereby improving conductivity (Fig. 4a). In addition, alkali ions (K⁺, Na⁺, or Li⁺) as intercalants can enhance stability.¹¹³ For example, Liu et al. synthesized a V₂O₅ cathode with a layered tunnel structure and a high pre-inserted potassium ion content (K-V₂O₅), where K⁺ acted as a pillar in the layered matrix, stabilizing the structure and widening the migration channels.¹¹⁴Table 2 presents the radii of different metal ions as intercalants. Compared with Zn²⁺, if the radius of the intercalating ion is larger than that of Zn, it will expand the channels. Common alkali-rich ions can accommodate the conditions of alkaline electrolytes but are susceptible to hydration effects. Transition metal ions can only remain stable under acidic conditions, and as the valence state of these ions increases, their radii decrease and their outer orbitals become more compact. Therefore, the rational design of the valence state of the intercalating ions is crucial.

Fig. 4 (a) Schematic illustration of different metallic elements act as pillars of layered structure. Illustration of high-resolution XPS spectra of (b) Cu 2p, (c) V 2p at the pristine, first charge and first discharge states of CuVO electrode.¹¹⁶ (d) Illustration of Zn²⁺ insertion/extraction in charge and discharge process.⁸³ (e) Optical images of contact angles between 2Zn-V₂O₅ electrodes and the electrolyte at different cycling times and (f) rate capability of all samples.⁸⁴ (g) Illustration depicting the transformation of ZIF-67 nanocubes into CoVO_x with varying morphologies.⁸⁵ (h) Illustration of the preparation process of Ce-V₂O₅ nanobelts.¹¹⁷

Table 2 The radii of different metal ions as intercalants

Intercalation ions		Ionic radius (Å)
Alkali-rich ions	Li^+	0.76
	Na^+	1.02
	K^+	1.38
Transition metal ions	Cu^2+	0.73
	Fe^2+	0.74
	Fe^3+	0.64
Others	Zn^2+	0.74
	Mg^2+	0.72
	Al^3+	0.54
	Ce^4+	0.97

---

The radius of Cu²⁺ (0.73 Å) is close to that of Zn²⁺ (0.74 Å), and its pre-insertion into VO can act as a “pillar” preventing structural collapse and enhancing electrochemical performance.¹¹⁵ Wu et al. selected Cu-MOF as the precursor and introduced the vanadium source into the synthesis of Cu-MOF, followed by calcination under an inert atmosphere to produce carbon-coated metal-ion pre-inserted V-based composite materials, CuVO. Notably, the addition of PVP during the MOF synthesis effectively reduced material agglomeration. XPS analysis revealed that Cu²⁺ was reduced to Cu⁺ during discharge, and Cu⁺ was re-oxidized to Cu²⁺, thus proving Cu²⁺ acted as a reactive active site, while also revealing the valence state change of V (Fig. 4b and c). Owing to the synergistic effect with the N-doped carbon coating, the resulting CuVO demonstrated a discharge capacity of 158.6 mA h g⁻¹ and a high capacitance retention of 95.6% at 5.0 A g⁻¹.¹¹⁶ The existence of oxygen deficiencies can modify the Gibbs free energy associated with the adjacent adsorption of Zn²⁺ ions onto the oxidized surface, influencing the thermal neutrality of the process. Li et al. combined defect engineering and cation doping techniques to prepare Cu-doped MIL-88A rod-like materials, followed by the addition of vanadium sources and annealing to obtain layered Cu-Fe₂VO₄ nanorods. Fig. 4d shows the intercalation and deintercalation of zinc ions during the charge and discharge cycles. Although the introduction of oxygen vacancies did not alter the preferred adsorption sites or transport routes, it weakened the electrostatic interaction between Zn²⁺ and lattice oxygen, thereby lowering the energy barrier. The addition of Cu²⁺ enhanced the material's conductivity, enabling Cu-Fe₂VO₄ to maintain 75% of its initial capacitance even after 8000 cycles.⁸³

Zeolitic imidazolate frameworks (ZIFs) are among the most extensively researched MOFs, renowned for their significant porosity and straightforward functionalization process.¹¹⁸ Liu and his colleagues employed ZIF-8 as a precursor template and controlled the amount of NH₄VO₃ powder added to prepare three samples of ZnVO_x electrode materials with porous 1D channels. Zn²⁺ ions could be seamlessly integrated into the Zn-V₂O₅ matrix, facilitating efficient ion diffusion and minimizing interfacial barriers. As depicted in Fig. 4e, the 2Zn-V₂O₅ electrode exhibited a beneficial contact angle with the electrolyte, indicating good wettability. This feature boosted ion accessibility and elevated the Zn²⁺ storage performance. Moreover, 2Zn-V₂O₅ exhibited superior rate performance, suggesting that an appropriate amount of Zn²⁺ in the electrode helps improve rate capability (Fig. 4f). The Zn||2Zn-V₂O₅ batteries achieved a specific capacity of 526.6 mA h g⁻¹ and maintained 84% of their initial capacity over 7000 cycles.⁸⁴ The porous structures of MOF-derived materials are often closed, leading to “dead mass”, which hinders the diffusion of Zn²⁺. Du et al., inspired by heterostructures, developed a dissolution–regrowth and conversion strategy, employing ZIF-67 as a sacrificial template and controlling the concentration of the V source to prepare CoVO_x species (CoVO_x-1, CoVO_x-2, and CoVO_x-4) (Fig. 4g). TEM images revealed that the CoVO_x-1 oxide, featuring low vanadium content, preserved the nanocube structure of the original MOF. As the V concentration increased, significant aggregation appeared, forming CoVO_x-2 nanoplates and CoVO_x-4 nanowires. When the CoVO_x-2 electrode, with its unique porous one-dimensional channel nanostructure, was applied as the AZIB cathode, it exhibited a specific capacity of 288.2 mA h g⁻¹, outperforming the other two. This demonstrated that the porous nanoplates facilitate the swift kinetics of Zn²⁺ intercalation and deintercalation processes.⁸⁵ In another study, a bimetallic Zn/V MOF precursor was pyrolyzed to obtain zinc-doped, carbon-containing porous vanadium oxide ZnV₂O₄@C as a cathode material. The energy storage process involved the simultaneous insertion of Zn²⁺ and H⁺. ZnV₂O₄@C exhibited a notable specific capacity of 425 mA h g⁻¹ at 0.5 A g⁻¹, due to its large specific surface area and porous, layered spinel-type tunnel structure, which offered numerous reactive sites.¹¹⁹

Additionally, Wang et al. used green-synthesized MIL-100(Fe) as a sacrificial template, followed by direct impregnation and subsequent pyrolysis to obtain Fe-doped vanadium oxide. With the implementation of MIL-100(Fe), the particle size of the material gradually decreased, enhancing the active surface area. The introduction of Fe reduced the adsorption energy of Zn²⁺ and improved the conductivity. Various ex situ techniques confirmed the Zn²⁺ insertion/extraction storage mechanism, and this study expands the potential methods for introducing other metal elements.⁸⁶ Rare-earth metals, such as the abundant Ce element, possess excellent redox properties and thermal stability. However, research on rare-earth metals is quite limited. Zhang et al. inserted Ce ions into porous vanadium pentoxide derived from V-MOFs using a simple hydrothermal method. Ce-V₂O₅ displayed a distinctive nanofelt morphology and possessed a substantial specific surface area of 73.6 m² g⁻¹, markedly exceeding that of vanadium pentoxide, which stands at 43.5 m² g⁻¹. Furthermore, Ce-V₂O₅ boasted an average pore diameter of 4.8 nm, surpassing the 3.6 nm of V₂O₅, thus facilitating the diffusion and transport of Zn²⁺ ions. This material exhibited outstanding rate capability and long-term cycling stability (Fig. 4h).¹¹⁷ Other scientists have also conducted similar research. For example, Ming et al. synthesized Mg²⁺-doped V₂O₅ interlayer Mg_0.34V₂O₅-nH₂O (MVO) nanosheets via a hydrothermal method. After 2000 cycles at 5 A g⁻¹, the material retained 97% of its initial capacity.¹¹¹ Jiang et al. achieved Al ion substitution doping via high-temperature quenching, resulting in Al-doped vanadium pentoxide. After undergoing 5000 cycles at a current density of 5 A g⁻¹, the material maintained 76% of its initial capacity.¹²⁰

V-MOF derivatives/conductive polymers

Despite V₂O₅ possessing a highly open pore structure, the robust electrostatic interactions between the V–O bonds and Zn²⁺, coupled with the dissolution of vanadium ions within the electrolyte, result in a considerable decline in its electrochemical performance.^121–123 Compositing with conductive polymers not only addresses the inherent low conductivity of V-MOFs but also acts as a supporting material for intercalation, enhancing the structural stability.^124–126In situ polymerization of aniline between V₂O₅ layers is a commonly used method in the intercalation engineering of layered vanadium pentoxide materials. The formation of long-chain polyaniline (PANI) enhances interlayer spacing, thereby facilitating the rapid diffusion of Zn²⁺ ions within the layers. Ran et al. prepared a composite material, PANI80-V₂O₅, where aniline polymerized between the V₂O₅ layers, increasing the V₂O₅ interlayer spacing from 5.76 Å to 14.31 Å. At the same time, the in situ polymerization and oxidation process led to nitrogen doping, which created oxygen vacancies in the material, reducing the bond strength between O²⁻ and Zn²⁺ in the V–O framework and alleviating the impact of Zn²⁺ intercalation on the material's structure. The π-conjugated structure of PANI prevents the dissolution of active species in the electrolyte. The material achieved an exceptionally high discharge capacity of 516.90 mA h g⁻¹ at 0.1 A g⁻¹ and retained 97.77% of its initial capacity after 3000 cycles at a higher current density of 10 A g⁻¹.⁸⁷ In another study, Zhang et al. employed a practical “two-in-one” approach, inserting PANI as pillar-like molecules into layered porous V₂O₅ (derived from V-MOFs, known as PVO) to serve as the cathode material for aqueous zinc-ion batteries (AZIBs). By incorporating PANI as “interlayer pillars”, they not only expanded the Zn²⁺ diffusion channels but also significantly enhanced the material's conductivity. This reduction in electrostatic attraction between Zn²⁺ and PVO prevented the collapse of the layered structure. As a result, the PVO cathode demonstrated an impressive rate performance of 375 mA h g⁻¹ at 5.0 A g⁻¹. After 2000 cycles at 8.0 A g⁻¹, it retained 91.8% of its initial capacity.⁸⁹ Zhao et al. synthesized MIL-88B (V) from VCl₃ and terephthalic acid, and on this basis, they prepared oxygen vacancies in V₂O₅ coated with polypyrrole (PPy) nanosphere nanoparticles (V₂O₅@PPy). Thanks to the exceptional conductivity and refined structure imparted by PPy, along with the presence of oxygen vacancies, V₂O₅@PPy-based AZIBs demonstrated a high capacity of 404.3 mA h g⁻¹ at 0.2 A g⁻¹.¹²⁷

The PANI formed via polymerization within the interlayer spaces of V₂O₅ plays an important role in enlarging these spaces and facilitating the insertion and extraction of Zn²⁺. Similarly, the conjugated electronic structure of PANI reduces the hydrolysis of vanadium in the electrolyte, enhancing its long-cycle stability and providing guidance for future research. The performance enhancement brought by the PPy coating mainly stems from the increased surface conductivity, but further exploration is needed to improve the internal structure.^128–130

In summary, the selection of metal ions or conductive organic polymers as intercalants requires comprehensive consideration of factors such as aqueous electrolyte compatibility, conductivity, application scenarios, and cost. In aqueous electrolytes, certain metal ions, such as Mn²⁺, are prone to dissolution in water, which can lead to structural collapse. Conductive organic polymers need to consider the proportion of hydrophilic groups to determine their stability. Na⁺ and K⁺ ions exhibit good conductivity, and their intercalation can significantly enhance conductivity and reduce internal resistance. However, conductive organic polymers typically need to be combined with carbon materials to ensure a sufficient electronic conduction rate. If superior rate performance is desired for the resulting AZIBs, metal ion intercalation should be prioritized. However, metal ions have larger volumes, which may induce structural stress. If better cycling performance is sought, more stable conductive organic polymers should be chosen. Moreover, the use of rare metal ions as intercalants increases costs. While there are precedents for the use of rare-earth metal ions in AZIBs, the extraction of rare-earth metals still incurs significant costs.

Manganese-based MOFs

In recent years, Mn-MOFs with porous structures have attracted considerable interest as cathode materials for advanced AZIBs owing to their robust coordination stability and excellent hydrolysis stability.^131–133 The specific capacity of Mn-based oxides is Mn²⁺/Mn³⁺: 308 mA h g⁻¹, Mn²⁺/Mn⁴⁺: 616 mA h g⁻¹. Although this is lower than V, their suitable operating voltage and well-established fabrication processes make them an important material for the development of AZIB cathodes.^134–136 Structures derived from MOFs, such as MnO, Mn₂O₃, Mn₃O₄, and α-, β-, γ-MnO₂, exhibit high specific surface areas and redox active sites. The synergistic effects when combined with other materials highlight their broad application potential (Fig. 5). A comparison of the electrochemical performance of V-MOFs with different design strategies is provided in Table 3.

Fig. 5 Schematic illustration of Mn-MOF derivatives combining with different materials.

Table 3 Electrochemical performance summary of some typical Mn-MOF and their derivative-based AZIB cathode materials

Design strategy	Electrode material	Voltage window (V)	Initial capacitance	Current density	Cycling stability (retention/cycles/current density)	Ref.
Pristine MOF	Mn-MOF-74	0.3–1.8	244.7 mA h g^−1	0.1 A g^−1	85.7%/1000/1 A g^−1	59
	Mn-H3BTC-MOF-4	1.0–1.9	138 mA h g^−1	0.1 A g^−1	93.5%/1000/3 A g^−1	140
MOF derivative	α-Mn2O3	0.9–1.9	225 mA h g^−1	0.05 A g^−1	41.2%/1700/2 A g^−1	147
	Mn2O3	1.0–1.8	154.8 mA h g^−1	0.1 A g^−1	98.7%/500/1 A g^−1	148
MOF derivative/carbon materials	MnO@C	0.8–1.9	57.4 mA h g^−1	0.1 A g^−1	160 mA h g^−1/1000/3 A g^−1	149
	δ-MnO2-C NA/CC	0.8–1.8	346.7 mA h g^−1	0.5 A g^−1	90.4%/50 000/4 A g^−1	150
	Mn3O4@C	0.8–1.9	331.5 mA h g^−1	0.2 A g^−1	99%/1900/3 A g^−1	151
	Mn2O3 flake@CNTFs	1–1.8	154.9 mA h cm^−3	0.3 A cm^−3	79.6%/3000/3 A cm^−3	152
	MOC@NGA	0.8–1.8	270 mA h g^−1	0.1 A g^−1	151.6 mA h g^−1/2000/1 A g^−1	153
	C@MnSe@GO-x	0.8–1.9	457.1 mA h g^−1	0.1 A g^−1	86.15%/1500/2 A g^−1	154
MOF derivative/metal ions	MnO/MnV2O4	0.2–1.8	342.8 mA h g^−1	0.1 A g^−1	81%/2000/10 A g^−1	155
	Ni-MnO/PC	0.8–1.8	347.4 mA h g^−1	0.1 A g^−1	91.1%/6000/3 A g^−1	156
	α-MnO2@ZIF-67	0.8–1.8	313.4 mA h g^−1	0.1 A g^−1	65%/1500/1 A g^−1	157

---

Pristine Mn-MOFs and their derivatives

Although Mn-based materials exhibit a high operating voltage, they often face limitations due to the Jahn–Teller effect and the issue of Mn dissolving during discharge.^137–139 Deng et al. innovatively selected MOF-74 as the cathode material. MOF-74 is composed of divalent transition metals and 2,5-dioxidoterephthalate, which is oxidized to form a highly active quinone structure. Benefiting from the organic/inorganic double electroactive sites, Zn/Mn-MOF-74 batteries exhibited a specific capacity of 252.6 mA h g⁻¹ at 0.1 A g⁻¹ in a 2 M ZnSO₄ electrolyte. The resulting batteries, after being packaged in a soft pouch, also exhibited excellent electrochemical stability under various mechanical deformations.⁵⁹ In another study, Yin et al. utilized a novel coordination-unsaturated Mn-MOF to address the sluggish Zn²⁺ insertion/extraction kinetics that significantly hinder the electrochemical performance of the cathode. This coordination unsaturation in Mn was achieved through the oxygen atoms from two adjacent –COO– groups, facilitating efficient transport of Zn²⁺ and electron transfer. Consequently, the MOF-based electrode retained 93.5% of its capacity even after 1000 cycles at a high current density, specifically 3000 mA g⁻¹.¹⁴⁰ Yang and co-workers constructed a Mn-MOF/CNT composite using a one-pot in situ solvothermal method. With the addition of CNTs, the Mn-MOF structure, which was initially compact, tended to intertwine with the CNTs, forming a crosslinked conductive network that facilitated the attraction of Zn²⁺ ions, which then intercalated into the electrode to form ZnMn₂O₄. Subsequently, H⁺ ions intercalated into MnO₂, forming MnOOH. Benefiting from the optimized Zn²⁺/H⁺ insertion/extraction and manganese deposition, the AZIBs fabricated from the resulting material exhibited a specific capacity of 260 mA h g⁻¹ at 50 mA g⁻¹ and showed almost no capacity decay after 900 cycles.¹⁴¹

Due to the multiple valence states of Mn, including +2, +3, +4, +5, and +7, among which Mn⁴⁺ is the most stable and possesses high reversible capacity and working voltage, MnO₂ and its electrochemical performance have become the most widely studied subjects. α-MnO₂, β-MnO₂, and γ-MnO₂ are three different crystal phases of MnO₂, where the crystal structure of α-MnO₂ consists of interconnected octahedra that form one-dimensional channels, while γ-MnO₂ contains smaller crystal particles.^142–144 Zhang and colleagues showed that α-MnO₂, β-MnO₂, and γ-MnO₂ share a common mechanism: the formation of layered Zn-buserite structures (B-Zn_xMnO₂·nH₂O) during initial discharge, enabling subsequent Zn²⁺ insertion.¹⁴⁵ Low-valent Mn compounds such as Mn₂O₃, Mn₅O₈, and Mn₃O₄ have also been explored as cathode materials for AZIBs, among which Mn₂O₃ has a theoretical specific capacity of 340 mA h g⁻¹. Despite exhibiting good electrochemical performance, their reaction mechanisms have not yet been clearly demonstrated.¹⁴⁶ Kang and co-workers applied Mn-MOF, which was derived into α-Mn₂O₃ through simple microwave treatment and calcination, and investigated its reaction mechanism using ex situ XRD. The experiments showed that at the “turning point” around 1.32 V, H⁺ and Zn²⁺ sequentially entered α-MnO₂, resulting in a gradual transformation of the discharge product, from a flower-like shape to a plate-like form. At elevated current densities, H⁺ insertion became the primary process in α-Mn₂O₃. The resulting material delivered a high specific capacity of 225 mA h g⁻¹; however, its performance rapidly declined to half after 1700 cycles.¹⁴⁷ The intrinsic low conductivity, slow redox kinetics, and large volume changes of Mn₂O₃ result in poor rate performance and structural collapse during long-term cycling. Wang et al. synthesized Mn₂O₃ multi-shell hollow nanospheres by oxidizing Mn-MOF microspheres as precursors. The hollow structure, with its high surface area and rapid electrolyte infiltration, along with effective volume change buffering, enabled the material to attain a reversible capacity of 453 mA h g⁻¹ at 0.1 A g⁻¹.¹⁴⁸

Mn-MOF derivatives/carbon materials composites

Mn has various oxides, including MnO, Mn₂O₃, Mn₃O₄, and α-, β-, γ-MnO₂. However, the dissolution of Mn²⁺ and the dispersion of Mn³⁺ during cycling severely limit the cycling performance of AZIBs fabricated from these materials as cathodes. Porous carbon materials exhibit good conductivity, electron transfer, and electrochemical performance.^157,158 When combined with Mn oxides, they not only enhance conductivity and structural stability but also act as a protective layer to inhibit the hydrolysis of Mn²⁺ and the formation of other by-products.¹⁵⁹ Jueun et al. investigated the effect of different carbon additives on the mass loading, capacity, stability, and kinetics of α-MnO₂. By combining electrochemical characterization, they identified the optimal conductive carbon component and characteristics that significantly enhanced energy density.¹⁶⁰ Furthermore, anchoring δ-MnO₂ uniformly onto carbon fibers could improve the material's flexibility and reduce internal electrostatic repulsion.¹⁶¹ These findings demonstrate that the addition of carbon materials enhances conductivity and enables broader application scenarios.

According to Yin et al., the Mn-BTC precursor was calcined at 700 °C to obtain layered spherical MnO@C. The distinctive layered interface created by the robust interaction between manganese oxide and carbon layers significantly enhanced the transfer rates of ions and electrons. Ex situ XRD analysis revealed that the structure of manganese oxide underwent a transformation into layered MnO₂ resulting from Mn²⁺ dissolution. This change made it easier to incorporate Zn²⁺, as illustrated by the overall electrochemical reaction for zinc-ion storage displayed in Fig. 6a. MnO@C exhibited a capacity of 412.4 mA h g⁻¹ at 0.1 A g⁻¹ and maintained remarkable stability through over 1000 cycles, even at a higher current density of 3 A g⁻¹.¹⁴⁹ Sun et al. calcined Mn-BTC to prepare MnO/C (700-Ar) and Mn₂O₃ (700-air) in Ar and air, respectively. Based on the analysis of the redox peaks from the CV, oxygen vacancies were identified as the preferred active sites. XPS results showed a characteristic peak for Mn⁴⁺ in 700-air, with a larger peak area for Mn³⁺ (Fig. 6b), indicating that oxygen vacancies altered the crystal and electronic structures, while also optimizing charge transfer impedance. The material labeled as 700-Ar displayed a specific capacity of 336.8 mA h g⁻¹ at 0.1 A g⁻¹. Additionally, after 10 000 cycles at 1.0 A g⁻¹, it still retained 73.8% of its initial capacity.¹⁶² Xu et al. successfully synthesized a MnO₂ nanocrystal-carbon hybrid framework through an in situ reaction using dimethylimidazole ligands and potassium permanganate. The ≈5 nm δ-MnO₂ nanocrystals were embedded within quasi-triangular carbon arrays, which enhanced ion penetration and sped up reaction kinetics. The as-prepared hybrid showed a uniform distribution of C, Mn, and O. Furthermore, the δ-MnO₂-C NA/CC electrode, featuring a porous and hydrophilic carbon framework, demonstrated the lowest contact angle among these electrodes, suggesting excellent wettability and accessibility to the electrolyte (Fig. 6c).¹⁵⁰

Fig. 6 (a) Schematic illustration of the ion transport mechanism of MnO@C.¹⁴⁹ (b) XPS spectra of Mn in 700-Ar and 700-air.¹⁶² (c) SEM images and the corresponding elemental mappings of δ-MnO₂-C NA/CC. Surface contact angles of various electrodes.¹⁵⁰ (d) Synthesis process of Od-Mn₃O₄@C NA/CC nanostructure and (e) supercell model of Mn₃O₄ with TDOS of the Mn₃O₄ and Od-Mn₃O₄ bulk phase.⁴⁵ (f) Illustration of the synthesis process of MnO_x@C@CNT.¹⁶⁷ (g) Capacity retention of the assembled device undergoing bending for 1000 cycles.¹⁵² (h) Evolution of the crystal structure of the MOC@NGA electrode during the energy storage process.¹⁵³ (i) Illustration of rGO/MnSi/MOF-C.¹⁶⁸

Mn₃O₄ possesses manganese valence states of +2 and +3, and its higher theoretical capacity of 469 mA h g⁻¹ compared with MnO₂ has garnered the interest of researchers.^163,164 However, the poor electrochemical activity of Mn₃O₄ along with the electrostatic repulsion from Zn²⁺ and the formation of irreversible by-products during charge/discharge processes limit its application in AZIBs. Converting MOFs, known for their high specific surface area and ultra-high porosity, into Mn₂O₃in situ can substantially enhance the contact area between the electrode material and the electrolyte. This, in turn, helps to reduce the resistance associated with ion intercalation and delamination.^165,166 Yin et al. formed 3D Mn₃O₄@C through nanosphere stacking pores during the thermal calcination process. Ex situ XRD and XPS analyses have confirmed that the zinc storage mechanism of this material involves the insertion and extraction of H⁺/Zn²⁺. Additionally, the process involves the presence of Mn³⁺, Mn⁴⁺, and partial dissolution of Mn²⁺. Since this structure provides fast ion transfer channels and effectively buffers volume changes during the charge–discharge process, Mn₃O₄@C showed almost no capacity decay after 1900 cycles.¹⁵¹ To address the cycling instability resulting from the Mn²⁺ disproportionation effect during extended cycling in AZIBs, Tan et al. employed valence engineering to introduce oxygen defects. Bulk oxygen defects could alter the MnO₆ octahedral structure, suppressing Mn²⁺ dissolution and thereby enhancing structural stability. The preparation process involved growing Mn-MOFs NA/CC on carbon cloth (CC) via solvothermal strategy, followed by calcination in air, where carbon removed lattice oxygen to generate oxygen-deficient Od-Mn₃O₄@C (Fig. 6d). EELS spectra verified the existence of oxygen defects. To investigate how these defects affected the conductivity of Mn₃O₄ with a spinel structure, the total density of states (TDOS) for both Mn₃O₄ and Od-Mn₃O₄ were calculated (Fig. 6e). The analysis indicates that the introduction of oxygen defects altered the charge density of Mn³⁺, leading to enhanced conductivity. In situ characterization further elucidated the Zn storage mechanism, which includes the transformation of Mn₃O₄ into R-MnO₂ during the electrochemical process, accompanied by a co-insertion equilibrium between H⁺ and Zn²⁺. The resulting Od-Mn₃O₄@C NA/CC electrode showed a specific capacity of 396.2 mA h g⁻¹ at 0.2 A g⁻¹. Moreover, it showcased remarkable cycling stability, enduring up to 12 000 cycles at a higher current density of 5 A g⁻¹. This electrode is also viable for the construction of flexible quasi-solid-state devices.⁴⁵

The composite of carbon nanotubes with Mn-based materials can enhance the hydrophilicity and conductivity of manganese oxides, further improving cycling stability under high current densities.¹⁵⁴ According to Jia et al., carboxylated carbon nanotubes were composited with Mn-MOFs via a simple hydrothermal method, and after carbonization, MnO_x@C@CNT was obtained (Fig. 6f). The carboxylated carbon nanotubes contributed to better hydrophilicity, facilitating electrolyte penetration, and the increased carbon content enhanced structural stability. The resulting material exhibited better cycling stability compared with MnO_x@C obtained by directly calcining Mn-MOFs, with only 2% capacity decay after 5000 cycles at 3 A g⁻¹.¹⁶⁷ Liu et al. used MIL-100 as a precursor and directly grew it on CNTF, which was then derived into a 3D vertically stacked Mn₂O₃@C flake-based porous electrode material. The assembled fiber-shaped ZIBs retained 90.1% of their initial capacity after 1000 cycles at 180° (Fig. 6g).¹⁵²

The interfacial gaps between metal oxides and carbon materials hinder fast ion transfer, and MOF precursors are prone to self-aggregation during the reaction, which covers active reaction sites.^169,170 Guo et al. noted that three-dimensional graphene aerogels (NGA) have excellent conductivity, large surface area, and layered pores. They combined NGA with carbon-encapsulated MnO nanoparticles and obtained MOC@NGA through in situ preparation and annealing. The carbon shell inherited from the Mn-MOF74 organic ligand could suppress the volume changes of manganese oxide. The continuous and rapid electron transfer conductive network established by the three-dimensional porous NGA inhibited the aggregation of the MOF precursor, and the Mn–O–C and Mn–N interfacial bonds at the interface bolstered the structural reversibility during repetitive charge–discharge cycles. Fig. 6h illustrates the crystal evolution of the MOC@NGA electrode throughout the energy storage process. The MOC@NGA cathode displayed a specific capacity of 270 mA h g⁻¹ at 0.1 A g⁻¹. After undergoing 2000 cycles at a current density of 1.0 A g⁻¹, it retained a capacity of 151.6 mA h g⁻¹.¹⁵³ In traditional three-phase mixed systems such as rGO/Mn₂SiO₄/MOF-C, slow electron conduction is a common issue. Dong et al. innovatively prepared a sandwich structure, placing Mn₂SiO₄ between MOF-C and rGO (Fig. 6i). Thanks to the optimized structure, the material exhibited excellent electron conduction and good Zn²⁺ storage capacity. The rGO/MnSi/MOF-C cathode initiated with a discharge capacity of 246 mA h g⁻¹ and peaked at 462 mA h g⁻¹ at 0.1 A g⁻¹.¹⁶⁸

Combining Mn-MOF derivatives with carbon-based materials can lead to an improvement in conductivity.^123,171 Currently, there are two main strategies for incorporating carbon-based materials: (1) the carbon elements contained in Mn-MOF are transformed into carbon layers through calcination, where valence engineering is an important approach for introducing oxygen vacancies, altering the electronic density and improving conductivity. (2) Mn-MOF is in situ grown on carbon nanotubes or graphene, followed by annealing to obtain derivatives. To suppress Mn²⁺ dissolution, a carbon encapsulation layer can be applied, which also helps alleviate volume changes during the electrode reaction process. Carbon nanotubes offer a stable structure and facilitate efficient electron transfer, thereby demonstrating excellent cycling stability.

Mn-MOF derivatives/metal ions

Binary metal oxides exhibit great electrochemical activity for their high conductivity and the multi-valent states of two transition metals.^172,173 Bai et al. constructed a MnO/MnV₂O heterostructure cathode material using hydrothermal and calcination methods. Due to the synergistic effect of the heterostructure, the material achieved a capacity of 342 mA h g⁻¹ when tested at 0.1 A g⁻¹.¹⁵⁵ Similarly, Leng et al. synthesized MnV₂O₄/C microparticles by annealing [Mn(phen)H₂O][V₂O₆] with a graphite template, resulting in MnV₂O₄ particles encapsulated in monolayer or few-layer graphene and attached to graphite sheets. Graphene coating safeguarded MnV₂O₄ from dissolving into the electrolyte, and the graphite template, in sheet form, hindered the clustering of MnV₂O₄ particles. DFT calculations revealed that oxygen deficiencies in MnV₂O₄ enhanced conductivity, aided in the transfer of electrons from V to Mn/O, and enabled the capture of hydrated Zn²⁺ ions. The dehydrated Zn²⁺ could easily intercalate into MnV₂O₄ with a low migration barrier of 0.84 eV.¹⁷⁴

The presence of nickel nanoparticles improves the conductivity of the electrode material, reduces electrochemical transfer impedance, and facilitates fast charge transfer.^175,176 Chen et al. employed a trimetallic MOF as a precursor, and through hydrothermal treatment and annealing, synthesized a manganese oxide composite (Ni-MnO/PC) with uniformly anchored doped Ni nanoparticles on porous carbon. The porous carbon promoted the interaction between ions in the electrolyte and the electrode, shortening the ion diffusion path, and enhancing the ion and electron transfer kinetics. Calculations suggested that doped nickel nanoparticles enhanced the sorption of Zn²⁺ ions onto the electrode's surface. The Ni-MnO/PC electrode retained 91.1% of its capacity after 6000 cycles at 3000 mA g⁻¹, and it could withstand stress from various degrees of bending, exhibiting stable cycling performance.¹⁵⁶ Lee's team hydrothermally synthesized Ni-MOF on CC and converted it into CC/NiO@C. By electrodepositing β-MnO₂, they obtained CC/NiO@C/MnO₂. The high capacity and cycling stability were attributed to the structural transformation of β-MnO₂ into birnessite MnO_xvia Mn²⁺ and the reversible Zn²⁺ (de)insertion process in NiO, represented as NiO ↔ Zn_xNiO.¹⁷⁷ Hollow microspheres formed from Ni@C nanoparticles, derived from Ni-MOF, feature high porosity, a large specific surface area, and a stable structure, which boost activity and enable swift electron transfer. Luo et al. in situ grew honeycomb-structured δ-MnO₂ nanosheets on the Ni@C hollow nanospheres. The hollow microsphere structure of the material played an important role in promoting the swift diffusion of ions and electrons. Additionally, it helped to alleviate the structural collapse of δ-MnO₂. Consequently, the material demonstrated an exceptional specific capacity of 352 mA h g⁻¹. Even after 2000 cycles at a higher current density of 2 A g⁻¹, it maintained 81% of its initial capacity.¹⁷⁸ Moreover, the addition of Co and its synergistic effect with Mn oxides is also considered as a great method to improve the electrochemical performance. For example, Ma et al. employed a hydrothermal method to synthesize MnCo₂O₄/CC, which they employed as the cathode in AZIBs. The average specific capacity of MnCo₂O₄/CC was 280.6 mA h g⁻¹.¹⁷⁹ Bai et al. in situ grew α-MnO₂@ZIF-67 composites at room temperature. The specific surface area rose notably to 5.1651 m² g⁻¹, accompanied by a 65-fold increase in the average pore diameter for adsorption. However, its long-cycle stability was relatively poor.¹⁵⁷

Prussian blue and Prussian blue analogues

Prussian blue (PB) and Prussian blue analogues (PBA) are a special type of MOF material with cyanide as the ligand, which can be represented by the general formula A_xM_a[M_b(CN)₆]_y·nH₂O, where A_x and M_a/M_b represent alkaline metal cations (K⁺/Na⁺) and transition metal cations (Fe²⁺, Co²⁺, Ni²⁺, Mn²⁺, etc.).^180,181 It possesses an open three-dimensional framework, low cost, ease of synthesis, and tunable chemical composition. When applied as cathode materials in AZIBs, it exhibits an ideal operating voltage. More importantly, its porous structure provides free space for the reversible insertion/extraction of Zn²⁺.¹⁸² PBAs offer relatively low specific capacity for Zn²⁺ cations (usually <80 mA h g⁻¹), and the insertion of Zn²⁺ leads to uncontrolled phase transitions and subsequent performance degradation. To overcome the low conductivity and stability of PB, Zhu et al. employed a simple electrochemical method to directly grow PB nanoparticles on expanded graphite (Fig. 7a). The Zn-ion battery-capacitor hybrid energy storage device designed based on this approach could maintain cycling stability for up to 12 000 cycles.¹⁸³ However, carbon-based materials only contribute to conductivity and stability, without adding active sites. In previous studies, [Fe(CN)₆]^3−/4− has been shown to exhibit high chemical activity, making it suitable for the storage of Na⁺ and K⁺.¹⁸⁴ Considering that the N atoms in [Fe(CN)₆]^3−/4− can act as hydrogen bond acceptors and interact with the N in PANI, thereby influencing the activity of PANI, Yao et al. designed a binder-free PANI-[Fe(CN)₆]⁴⁻ film (CC-PANI-FeCN). The specific capacity of CC-PANI-FeCN at different current densities is shown in Fig. 7b. After 1000 cycles, CC-PANI-FeCN retained 71% of its capacity, while pure PANI as the cathode only retained 17%. Moreover, the resulting material could be soft-packed to accommodate folding at different angles.¹⁸⁵

Fig. 7 (a) Schematic diagram of PB@EG synthesis.¹⁸³ (b) GCD profiles of CC-PANI-FeCN at different current densities.¹⁸⁵ (c) Schematic diagram of the phase transformation for KMnHCF electrode in 30 M KFSI + 1 M Zn(CF₃SO₃)₂ electrolyte.¹⁸⁶ XPS spectra of (d) Fe 2p and (e) Mn 2p of Mn-PBA.¹⁸⁷ (f–i) SEM images of KMHCF sheets after different charge and discharge cycles.¹⁸⁸ (j) Framework of Prussian blue analogues.¹⁸⁹ (k) The synthetic process of CoMn-PBA HSs.¹⁹⁰ (l) Raman spectrum of VO-RT-21 at different states.¹⁹¹ (m) Schematic illustration of reversible Zn²⁺ intercalation/extraction and phase transition in AlHCF frameworks during the charge/discharge process.¹⁹²

PBAs contain a significant number of vacancies and water molecules. The vacancies can lead to significant distortion of the crystal structure, affecting the coordination bonds, while the presence of water molecules hinders the diffusion rate of Zn²⁺. Moreover, the single redox centre results in poor reversible Zn storage capability. Introducing Mn into PBAs to form Mn³⁺/Mn²⁺ and Fe³⁺/Fe²⁺ dual active centres is an important strategy to optimize the performance of PBAs.^193,194 Fe and Mn can provide additional capacity through redox reactions during charge/discharge cycles. Furthermore, the redox potentials of Mn and Fe are close, leading to minimal changes in the battery's discharge voltage.¹⁹⁵ In recent years, Deng et al. employed in situ XRD characterization to reveal the reason why KMnHCF (K_1.6Mn[Fe(CN)₆]_0.94·0.63H₂O) stabilizes its capacity at 100 mA h g⁻¹ after 400 cycles when used as a cathode material. The insertion of Zn²⁺ induces a strong Teller effect on Mn³⁺, leading to lattice distortion. The MnN6 octahedron transforms into MnN₄ tetrahedra, which then convert into ZnN₄ tetrahedra (Fig. 7c). The transformed structure has a wider ion channel compared with KMnHCF.¹⁸⁶ Yang's team prepared Mn-PBA through a simple co-precipitation method and controlled the morphology by adjusting the gradient concentration, aiming for efficient and reversible Zn²⁺ insertion/extraction. XPS analysis confirmed the presence of both Fe²⁺ and Fe³⁺ in Mn-PBA, with Fe²⁺ being the dominant species. As the Mn content increased during the reaction process, the peak of Mn³⁺ gradually intensified (Fig. 7d and e). In situ Raman spectroscopy revealed the mechanism of Zn²⁺ redox reactions with Mn and Fe acting as dual active centers. More importantly, this method is suitable for large-scale production, offering higher economic benefits.¹⁸⁷ To further enhance the adsorption capacity of Mn³⁺/Mn²⁺, Tan et al. employed directed functional group engineering to synthesize manganese (MnHCF) enriched with OH groups. XPS analysis confirmed that the conversion between Mn²⁺ and Mn³⁺ was more frequent in OH-rich MnHCF. The enhancement effect of hydroxyl groups on Zn²⁺ adsorption (E_a = −0.35 eV) was confirmed by DFT calculations. OH-rich MnHCF achieved an energy density of 228.8 W h kg⁻¹ at 0.1 A g⁻¹.¹⁹⁶ Although MnHCF possesses a good theoretical specific capacity, its performance is limited by the dissolution of Mn from the cathode, the Jahn–Teller effect of Mn³⁺, and the formation of MnOOH byproducts. Doping with Zn can improve the stability, but it leads to a reduction in the number of active sites, resulting in performance degradation.¹⁹⁷ Potassium manganese hexacyanoferrate (KMHCF) was initially used as an electrode material for potassium-ion batteries, as its pores are filled with larger K⁺ ions (1.38 Å) and it adopts a monoclinic crystal structure, thus offering better structural stability. Cao et al. added the surfactant PVP during synthesis, which preferentially adsorbs onto individual crystal faces to guide growth into anisotropic shapes. Additionally, it can weaken the electrostatic attraction between CN⁻ and H₂O, thereby reducing the presence of H₂O in the lattice gaps and enhancing the diffusion rate of Zn²⁺. During cycling, although some ions are exchanged, the cubic structure is still maintained (Fig. 7f–i).¹⁸⁸

Copper hexacyanoferrate (CuHCF) has an open three-dimensional structure and is composed of a face-centered cubic framework of transition metal cations. In this structure, Fe(III) acts as a low-spin transition metal ion, coordinated by six carbon atoms, while Cu(II) serves as a high-spin transition metal ion, coordinated by six nitrogen atoms (Fig. 7j). The yellow-brown CuHCF, obtained from a solution of K₃Fe(CN)₆ and CuSO₄ through sonication and settling, has a lattice parameter of 10.1 Å, as shown by XRD characterization. In electrochemical tests, CuHCF exhibited a cathodic peak at approximately 0.6 V and a corresponding anodic peak at approximately 0.8 V, which may be due to Zn entering the lattice gaps. Based on this, the Zn storage mechanism of CuHCF was inferred as follows: xZn²⁺ + 2xe⁻ + CuHCF ⇔ Zn_xCuHCF (0 < x < 0.5).¹⁸⁹ Copper insertion can also serve as an important strategy to alleviate Mn dissolution and the Jahn–Teller distortions of Mn–N₆ octahedra. The team of Yu synthesized a CuMn PBA composite nanostructure with Mn vacancies and Cu substitution via a simple co-precipitation method, controlling the copper and manganese sources. The resulting material effectively mitigated the Jahn–Teller distortions of Mn–N₆ octahedra, while demonstrating robust cycling stability, maintaining 73.15 mA h g⁻¹ over 2000 cycles at 3 A g⁻¹.¹⁹⁸

Co-substituted Mn-PBAs also suppress the Jahn–Teller distortions of Mn³⁺. Zeng et al. considered that the hollow structure could alleviate the structural strain during the ion insertion/extraction process, thus creatively synthesizing CoMn-glycerate solid spheres as precursors. Subsequently, a one-step ion exchange was applied to obtain the surface-roughened spherical product, Co-substituted Mn-rich PBA hollow spheres (CoMn-PBA HSs) (Fig. 7k). Thermogravimetric analysis showed that the coordination water content of CoMn-PBA HSs was approximately 7.1%, lower than that of Co-PBA HSs, while BET analysis revealed the highest specific surface area of 89.8 m² g⁻¹. The CoMn-PBA HSs electrode exhibited a CV curve similar to that of the Mn-PBA HSs electrode, confirming that the inclusion of Co did not serve as an active centre. CoMn-PBA HSs demonstrated a reversible capacity of 128.6 mA h g⁻¹ at 0.05 A g⁻¹, retaining 76.4% after 1000 cycles.¹⁹⁰ Cao et al. integrated Co and Ni into a PBA and employed an in situ co-precipitation method to grow it on carbon nanotubes. Due to the synergistic effect of Co and Ni, along with the crosslinked conductive network of carbon nanotubes, the resulting CoNiHCF/CNTs composite displayed a reversible capacity of 124.9 mA h g⁻¹ at 0.05 A g⁻¹.¹⁹⁹

Additionally, researchers have found that PBAs substituted with other metal ions in place of Fe also exhibit good performance.²⁰⁰ Meng et al., inspired by the multivalent states (+2/+3/+4/+5) of V, introduced it into the PBA via a simple precipitation method. To alleviate the poor cycling stability of PBA due to the dissolution of V during cycling, polyethylene pyrrolidone was added during the synthesis process to control the precipitation rate. The resulting VO-RT-21 exhibited smaller size and fewer defects. At 0.1 A g⁻¹, the theoretical specific capacity was 190 mA h g⁻¹. Ex situ Raman spectroscopy showed that the Raman peaks of Fe-CN-V nearly disappeared after cycling, indicating that the surface material dissolved in water to form vanadium oxide (Fig. 7l).¹⁹¹ Kong et al. summarized previous work and found that cathodes containing high-valent M_a, such as Cu, Co, and Zn, typically deliver higher operating voltages. Therefore, they creatively introduced Al³⁺ into PBA and, by compounding it with graphene, altered the particle stacking state and improved the low conductivity. The Zn²⁺ insertion/extraction and phase transition in AlHCF frameworks are shown in Fig. 7m. Although the resulting AlHCF delivered a high output voltage of 1.8 V (vs. Zn/Zn²⁺), its theoretical specific capacity was relatively low, which may be due to the smaller radius of Al compared with Zn.¹⁹² Similarly, Xu et al. introduced Ti into PBA; however, the material's stability and theoretical capacity were relatively low.²⁰¹ Xue et al. combined amorphous SnHCF with PANI, and the resulting SnHCF/PANI exhibited a high specific capacity of 136.8 mA h g⁻¹ at 0.5 A g⁻¹.²⁰²

In summary, V-based MOFs offer the highest theoretical specific capacity due to their multiple oxidation states. However, they suffer from low operating voltages, structural collapse during cycling, and possess certain toxicity. Mn-based MOFs, despite their high operating voltage and environmental friendliness, exhibit poor electrical conductivity, and the disproportionation reaction of Mn³⁺ leads to Mn dissolution. The introduction of rigid ligands or compositing with other materials can optimize structural stability. Designing surface coatings can effectively inhibit Mn³⁺ dissolution. PBAs possess an open three-dimensional framework structure and are easy to prepare, but they are limited by low electrical conductivity, fewer active sites, and side reactions caused by lattice defects. Introducing other high-activity metals and adjusting synthesis conditions to reduce defects can effectively increase specific capacity. Additionally, in situ characterization techniques should be employed to explore the deactivation process of electrode materials, combined with theoretical calculations to optimize ion diffusion pathways.

Anodes for AZIBs

The anode of AZIBs encounters substantial obstacles, including uncontrollable dendrite formation, the hydrogen evolution reaction, and Zn corrosion issues.^203–205 These issues become more pronounced at high current densities, as they accelerate the depletion of Zn²⁺ at the electrode/electrolyte interface. This leads to severe concentration polarization, uneven zinc ion deposition, and excessive dendrite growth, all of which can adversely affect the battery's performance and lifespan.^206–208 This results in poor cycling performance and may even cause the dendrites to penetrate the separator, inducing short circuits. Furthermore, metallic zinc's inherent thermodynamic instability in aqueous electrolytes leads to inevitable hydrogen evolution and corrosion at the electrode–electrolyte interface, generating inactive byproducts like ZnO and Zn(OH)₂.^209–211

The construction of protective layers, which directly affects the dissolution and precipitation of Zn²⁺, is considered the most promising and practically valuable approach. Artificial layers can be used to improve the stability and durability of zinc anodes in batteries by leveraging their spatial shielding effect. This effect helps to inhibit dendrite growth, hinder water-induced side reactions, and homogenize the flux of Zn²⁺ ions. By covering the surface of the Zn metal anode with nanoscale or sub-nanoscale porous materials as a protective layer, the direct contact between zinc and the aqueous solution is reduced. This, in turn, mitigates the corrosive effect of active water molecules on Zn, thereby prolonging the lifespan of the battery.²¹⁹ Meanwhile, these porous materials can also induce uniform Zn²⁺ deposition, improving coulombic efficiency and cycle life (Table 4). MOFs and their derivatives function as materials that regulate Zn²⁺ diffusion, nucleation, and deposition, enabling highly reversible zinc plating and stripping without dendrite formation (Fig. 8).

Fig. 8 Summary of pristine MOF and their derivative serve as anode coating materials.

Table 4 Electrochemical performance summary of some typical MOF-based AZIB anode materials

Electrode material	Initial capacitance	Current density	Cycling stability (retention/cycles/current density)			Ref.
UIO-67-2D/Zn	240 mA h g^−1	1 A g^−1	81%	1500	2 A g^−1	41
Zn@ZIF-L	342.7 mA h g^−1	0.5 c	84.9%	250	0.5 A g^−1	212
Zn-BTC	220 mA h g^−1	0.5 A g^−1	81.1%	1000	2 A g^−1	213
Zn@UO-24	243.5 mA h g^−1	0.5 A g^−1	99.3%	600	0.2 A g^−1	214
ZIF-7x-8@Zn	312 mA h g^−1	1 A g^−1	86%	2000	5 A g^−1	42
Zn@A-ZIF-8	—	—	≈100%	2000	1 A g^−1	215
Zn/SITL	240 mA h g^−1	1 A g^−1	86%	2000	5 A g^−1	216
D-UiO-66@Zn	200 mA h g^−1	1 c	92.9%	2000	5 A g^−1	217
MOF-74	208 mA h g^−1	0.2 A g^−1	77.4%	1000	0.2 A g^−1	33
PPZ@Zn	140 mA h g^−1	4 A g^−1	86.3%	1200	1 A g^−1	218
HKUST-1@Zn	183 mA h g^−1	0.2 A g^−1	69%	500	1 A g^−1	219
ZIS@Zn	107 mA h g^−1	4 A g^−1	88%	1600	2 A g^−1	208
ZnPTA@Zn	80 mA h g^−1	0.5 A g^−1	77.9%	5500	2 A g^−1	43

---

The structured channels within porous materials can direct the deposition of zinc ions in a uniform and orderly fashion. For instance, Guo et al. in situ decorated the porous UiO-66 artificial layers, prepared through a simple solvothermal reaction, onto the zinc anode. The interfacial layer of UiO-66 possessed a porous structure, which selectively allowed Zn²⁺ to traverse the electrode–electrolyte interface due to size-exclusion effects.²¹⁴ However, the use of binders results in thick coatings, leading to severe polarization and reduced Zn²⁺ transfer efficiency. The pre-formed porous structure, featuring inherent defects, permits the passage of free water molecules and solvated zinc ions through these gaps, enabling direct contact with metallic Zn.²²⁰ He et al. utilized an in situ method to deposit a binder-free ZIF-L layer (approximately 3 μm thick) onto Zn surface. DFT calculations revealed that the binding energies of Zn and H on the ZIF-L surface were −0.82 eV and −4.01 eV, respectively, both of which were lower compared with those on bare Zn (−0.67 eV and −1.49 eV) (Fig. 9a). This indicates that the ZIF-L layer suppressed the Zn²⁺ flux, altered zinc deposition, and modified the solvation structure.²¹² Luo et al. utilized a gas–solid interaction between 2-methylimidazole vapor and the Zn oxide protective layer to produce a slender, consistent MOF interlayer on the Zn surface. To validate the absence of defects in the MOF interphase, [Cu(EDTA)]²⁺ served as a probe, with the results depicted in Fig. 9b confirming the integrity of the MOF layer. The all-MOF-based interphase had a thickness of only 700 nanometers and was characterized by its defect-free nature. This prevented direct contact between the zinc metal and the aqueous electrolyte, assisting in the removal of solvent molecules from Zn²⁺ ions prior to their electrochemical deposition. Raman spectroscopy analysis verified that Zn²⁺ ions underwent desolvation within the MOF pores, thereby preventing side reactions triggered by active water molecules. Additionally, the uniform interphase aided in directing the even deposition of Zn. When tested in a Zn||Cu asymmetric cell at 1 mA cm⁻², the cell exhibited a high coulombic efficiency of 99.7% after 3200 cycles.²²¹ In addition, Zhang's team used a pre-oxide gas deposition strategy to construct a uniform and dense MOF film with a controllable thickness ranging from 150 to 600 nm on binder-free zinc foil (Fig. 9c). The study found that when the thickness was insufficient, the film tended to peel off during cycling. A ZIF-8 layer thinner than 600 nm could be used to mitigate corrosion, dendrite formation, and H₂ evolution.²²²

Fig. 9 (a) Schematic illustration of binding energy of Zn²⁺/H⁺ adsorbed on Zn(002) surface and unit ZIF-L.²¹² (b) Digital image depict bare Zn and MOF-coated Zn immersed in [Cu(EDTA)]²⁺ solution, along with a schematic representation showing the exclusion of [Cu(EDTA)]²⁺ ions by the MOF interlayer.²²¹ (c) Pre-oxide gas deposition of ZIF-8 thin films on Zn foil.²²² (d) Diagram highlighting the significant effectiveness of ultrathin, defect-free ZIF-7x-8 membrane-like structures in mitigating water-related byproducts and preventing the formation of Zn dendrites.⁴² (e) Illustration of selective ion transport performance of MOF-801.²¹⁶ (f) Voltage profiles of Zn deposition on various Cu substrates.²¹⁷ (g) Diagram depicting crystalline ZIF-8 and a continuous layer of A-ZIF-8, emphasizing their ability to conduct Zn ions.²¹⁵

MOFs have flexible pore windows, but ion clusters pass through the pore via stretching and vibration, leading to incomplete desolvation of solvated zinc ions. It cannot completely prevent solvent molecules from diffusing through the interparticle gaps between individual MOF particles.^223,224 Xu and colleagues employed a swift current technique to directly synthesize ultra-thin, defect-free ZIF-7x-8 layers featuring hydrophobic, rigid sub-nanopores of 0.3 nm in diameter on zinc metal surfaces. These sub-nanopores, due to their hydrophobic nature, intensified the desolvation process of zinc ions in solution, thereby efficiently mitigating adverse reactions triggered by water. SEM images of the electrode material during the cycling process showed that Zn²⁺ initially deposits vertically on the zinc foil surface, and as the deposition amount increases, Zn²⁺ begins to deposit horizontally, as shown in the schematic in Fig. 9d. The consistent electric field across the rigid sub-nanopores facilitated even deposition of Zn²⁺, preventing the emergence of Zn dendrites. The ultrathin, flawless ZIF-7x-8 coating on Zn–metal exhibited remarkable stability, enduring for more than 2200 hours. Additionally, the PANI-V₂O₅||ZIF-7x-8@Zn full cell showed stability for 2000 cycles with 14% capacity loss.⁴²

The cycling stability of AZIBs using vanadium oxide as the anode is frequently hindered by zinc metal corrosion induced by vanadium ions. Considering the difference in size between hydrated zinc ions (4.30 Å) in the electrolyte and larger vanadium ions (8.34 Å), Lee and his team chose MOF-801 nanoparticles, featuring a pore size of 6.0 Å, to encapsulate the zinc foil. This resulted in a layer that facilitated selective ion transport (SITL) (Fig. 9e). MOF-801 is stable in mildly acidic electrolyte containing VO₂⁺. The larger pores in the SITL promoted the homogenization of zinc ion flux, leading to smooth and uniform Zn deposition without zinc dendrite growth.²¹⁶ To improve Zn²⁺ selectivity, Xu et al. proposed a new approach by using UiO-66 as a precursor. Through defect engineering and acid treatment, they fabricated a quasi-solid electrolyte interphase on the Zn surface composed of defect MOF nanoparticles (D-UiO-66) and two zinc salt electrolytes as the Zn ion reservoir. The positively charged oxygen deficiencies within D-UiO-66 underwent Lewis acid–base interactions with electrolyte anions, resulting in the creation of anion-modulated MOF channels that boosted Zn²⁺ mobility. The nucleation potential of D-UiO-66 was found to be lower than that of bare copper, proving that it reduced the energy barrier for Zn nucleation and growth (Fig. 9f). The highly concentrated electrolyte within the porous MOF layer expanded, alleviating concentration polarization and ensuring uniform Zn²⁺ deposition. The resulting material achieved a CE of 99.8% at 1 mA h cm⁻², with stability exceeding 1800 h, and even demonstrated over 480 h of cycling stability.²¹⁷

The rigid lattice of crystalline MOFs typically possesses limited mechanical flexibility, which may cause structural degradation because of the volume fluctuations in the metal anode during battery cycles. Xiang et al. constructed a continuous approximately 2.2 μm amorphous ZIF-8 layer (A-ZIF-8) on zinc foil. Under a current density of 10 mA cm⁻², the material exhibited high stability after more than 5500 cycles, and it could withstand various bending conditions. The crystal schematic of ZIF-8 and A-ZIF-8 is shown in Fig. 9g. The Zn foil coated with A-ZIF-8 was obtained by an in situ spray strategy, followed by calcination at 150 °C for 0.5 and 8 hours in a tube furnace to construct Zn@A-ZIF-8 and Zn@C-ZIF-8 anodes. SEM images revealed that after different cycles, Zn@C-ZIF-8 dendrites grew along the grain boundaries, penetrating the C-ZIF-8 layer after 50 cycles, whereas on the Zn@A-ZIF-8 anode, a uniform zinc deposition layer formed and grew. Additionally, LSV testing demonstrated that Zn@A-ZIF-8 had the lowest onset potential (−1.79 V) and the best inhibition effect on the hydrogen evolution reaction.²¹⁵

In summary, to further improve the coating technology on zinc foil to suppress hydrogen evolution reactions and zinc dendrite growth, adjustments can be made in the following three aspects: (1) in situ construction of protective layers via methods such as in situ synthesis, electrodeposition, or gas deposition, forming a tightly bonded layer; (2) controlling pore size to selectively allow the passage of Zn²⁺, facilitating the desolvation of hydrated hydrogen ions, while preventing the ingress of anode products that may cause side reactions; (3) amorphous MOFs offer unique advantages in addressing the volume changes of zinc foil, making them worth further exploration.

Conclusion

Recently, the innovative material MOF has gained popularity in catalysis and energy storage applications, attributed to its high surface area, adjustable pore dimensions, structural versatility, and presence of active metal centers. Aqueous zinc-ion batteries, as a new class of energy storage systems, have garnered extensive research attention due to the abundance of zinc resources, substantial theoretical capacity, and cost-effective and safe electrolytes.^225–227 Currently, the energy storage mechanisms of AZIBs are mainly classified into two types: (1) reversible insertion/extraction of Zn²⁺ and (2) co-insertion/extraction of H⁺ and Zn²⁺. To minimize the impact of side reactions and improve the coulombic efficiency of AZIBs, it is necessary to optimize the insertion/extraction process of Zn²⁺. MOFs, with their open channels and pores that enhance electrolyte permeability and accelerate ion transport, align well with the energy storage mechanisms of AZIBs, making them promising electrode materials.

Typically, the insertion of Zn into cathode electrodes causes volume expansion, which can damage the material's structure and lead to rapid performance degradation. V-MOFs and Mn-MOFs can serve as precursors, and through high-temperature calcination, they form oxides with multiple valence states. Both V-based and Mn-based oxides possess typical layered and tunnel structures, which can provide space for the insertion of Zn²⁺. However, traditional MOFs often face drawbacks such as low conductivity and instability during long cycling. Through combining them with carbon-based materials, inserting other metal ions, or using conductive polymers, their performance can be significantly improved. Notably, the incorporation of metal ions and conductive polymers can also serve as “interlayer pillars”, widening the interlayer spacing, accelerating the kinetics of zinc storage, and enhancing structural stability to prevent collapse.^228,229

Zinc deposition on the anode can lead to dendrite formation, which damages the separator, while hydrogen evolution on the cathode generates OH⁻ ions, causing corrosion of the Zn foil. Anode protective layers, as a simple and cost-effective method, improve cycle life by optimizing the electrolyte–electrode interface and preventing direct contact between the electrode and the aqueous electrolyte. MOFs, as protective layers, have uniform pore sizes that can regulate Zn²⁺ flux and guide uniform Zn deposition, thereby preventing dendrite formation. Traditional methods for constructing protective layers involve pre-preparing MOFs and coating them onto the zinc foil with a binder. However, this approach brings inevitable defects, as solvated Zn ions contact the zinc foil and lead to coating peeling.^230–232In situ growth, which avoids the use of binders, has become an important strategy for modifying anode protective layers. In this review, we summarize recent strategies for modifying AZIB anodes and cathodes using MOFs, and offer critical insights into these methods (Fig. 10). Based on this, we propose the following suggestions, hoping to guide future research and development of AZIB electrodes:

(1) The reaction mechanism of the cathode is closely related to the crystal structure of Zn²⁺ ions, the type of solute, and the solvation effect. It is commonly accepted that the key mechanism involves the reversible incorporation and release of Zn²⁺ or H⁺/Zn²⁺. For manganese-based oxides, however, the reaction mechanism remains unclear. Although the co-insertion of Zn²⁺ and H⁺ has been shown to explain the two-phase voltage profile, their complex reaction products, such as MnOOH, Zn_xMnO₂, ZnMn₂O₄, and other Zn–Mn-oxides, still pose challenges in analyzing the true active components. Moreover, current research on the energy storage mechanism of AZIBs is based on ex situ characterization. By utilizing in situ characterization methods alongside theoretical simulations, researchers can gain a deeper understanding of how Mn-based oxides store energy. This understanding can then inform the design and optimization of electrode materials, ultimately enhancing their performance.

(2) Currently, the MOF materials used for developing AZIBs cathodes are mainly V-MOF, Mn-MOF, and Prussian blue. Although these materials possess well-ordered frameworks and can form oxides with layered or tunnel structures upon calcination, the research is still quite limited. Many MOFs have ideal porosities that can provide space for Zn storage. Recent studies have demonstrated that Cu-MOF is a highly promising energy storage platform, showing good rate performance when applied to AZIBs. Research on anode materials has mainly focused on a specific class of materials (e.g., ZIFs), with efforts concentrated on how to make MOFs tightly adhere to zinc foil. However, exploring new protective layer materials or composite strategies with organic polymers to improve the strength of the protective layer could contribute to the further development of anode stability.

(3) The reversible insertion/extraction of Zn²⁺ in the cathode leads to expansion of the electrode material and an increase in lattice spacing. However, this can damage crystals with rigid structures and cause structural collapse after multiple cycles. Developing amorphous cathode materials can accommodate volume expansion, and due to the more isotropic ion diffusion pathways and numerous vacancy sites in amorphous materials, the resulting materials offer more active sites, greater conductivity, and faster Zn²⁺ diffusion kinetics. On the anode, zinc dendrites grow along grain boundaries and may pierce the separator after a limited number of cycles. The use of an amorphous protective layer can regulate a uniform zinc deposition layer, thereby suppressing the hydrogen evolution reaction. Moreover, amorphous materials show potential in the development of flexible batteries.

(4) AZIBs are promising as energy sources for wearable and flexible devices for the safety of their electrolytes. However, attempts to develop flexible pouch designs are still limited, mainly because external folding can cause the collapse of the anode structure. Moreover, folding of the anode material can damage the zinc foil protective layer. Defects in the protective layer allow hydrated zinc ions to penetrate, which can trigger hydrogen evolution reactions and cause corrosion of the zinc foil. Therefore, we anticipate that future research will focus on using protective layers with proven flexibility as anodes, and further investigate their practical applications in flexible devices. Additionally, exploring the design of separators or the fabrication of independent membranes will be essential for enhancing performance.

Fig. 10 Future challenges of MOF-based anode and cathode materials for AZIBs.

Author contributions

Yingying Wang: writing – original draft. Writing the initial draft with substantive translation. Tao Pan: visualization. Presentation of the published work in figures and chart arrangement. Sicong Zhang: data curation. Organizing and categorizing outstanding work in this field. Qing Li: conceptualization. Proposing the development trajectory and design strategies for aqueous zinc-ion batteries based on MOF electrodes. Huan Pang: writing – review & editing. Critical review, commentary and revision.

Data availability

No primary research results, software or code have been included and no new data were generated or analysed as part of this review.

Conflicts of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (52371240), Natural Science Foundation of Jiangsu Province (BK20230566). We also acknowledge the Priority Academic Program Development of Jiangsu Higher Education Institutions, Natural Science Research Project of Guangling College, Yangzhou University (ZKZD23005), the Universities’ Philosophy and Social Science Research in Jiangsu Province (2023SJYB2088), and the technical support we received at the Testing Center of Yangzhou University.

References

1. X. Li, Z. Chen, Y. Yang, S. Liang, B. Lu and J. Zhou, The phosphate cathodes for aqueous zinc-ion batteries, Inorg. Chem. Front., 2022, 9, 3986–3998,  10.1039/D2QI01083F.
2. E. Sayed, A. Olabi, A. Alami, A. Radwan, A. Mdallal, A. Rezk and M. Abdelkareem, Renewable Energy and Energy Storage Systems, Energies, 2023, 16, 1415,  DOI:10.3390/en16031415.
3. M. Chen, C. He, Q. Liu, W. Deng and C.-F. Sun, A mass-producible polyoxovanadate cathode for ultrafast-kinetics zinc-ion batteries, Inorg. Chem. Front., 2024, 11, 3643–3652,  10.1039/D4QI00814F.
4. H. Dou, X. Wu, M. Xu, R. Feng, Q. Ma, D. Luo, K. Zong, X. Wang and Z. Chen, Steric–hindrance Effect Tuned Ion Solvation Enabling High Performance Aqueous Zinc Ion Batteries, Angew. Chem., Int. Ed., 2004, 63, e202401974,  DOI:10.1002/anie.202401974.
5. X. Wang, H. Hong, S. Yang, S. Bai, R. Yang, X. Jin, C. Zhi and B. Wang, A UiO-66-NH₂ MOF derived N doped porous carbon and ZrO₂ composite cathode for zinc-ion hybrid supercapacitors, Inorg. Chem. Front., 2023, 10, 2115–2124,  10.1039/D2QI02777A.
6. S. Wu, Y.-F. Wang, W.-L. Liu, M.-M. Ren, F.-G. Kong, S.-J. Wang, X.-Q. Wang, H. Zhao and J.-M. Bao, A high-capacity and long-life aqueous rechargeable zinc battery using a porous metal–organic coordination polymer nanosheet cathode, Inorg. Chem. Front., 2018, 5, 3067–3073,  10.1039/C8QI00959G.
7. Q. Li, Y. Peng, Y. Wang and H. Pang, Al/Cu-Doped V₆O₁₃ Microflowers as Cathodes for Rechargeable Lithium-Ion Batteries, Energy Fuels, 2024, 38, 19913–19919,  DOI:10.1021/acs.energyfuels.4c03696.
8. Y. Shi, B. Zhu, X. Guo, W. Li, W. Ma, X. Wu and H. Pang, MOF-derived metal sulfides for electrochemical energy applications, Energy Storage Mater., 2022, 51, 840–872,  DOI:10.1016/j.ensm.2022.07.027.
9. X. Zhou, J. Li, G. Zhou, W. Huang, Y. Zhang, J. Yang, H. Pang, M. Zhang, D. Sun, Y. Tang and L. Xu, Manipulating d-d orbital hybridization induced by Mo-doped Co9S8 nanorod arrays for high-efficiency water electrolysis, J. Energy Chem., 2024, 93, 592–600,  DOI:10.1016/j.jechem.2024.02.033.
10. A. A. Kebede, T. Coosemans, M. Messagie, T. Jemal, H. A. Behabtu, J. Van Mierlo and M. Berecibar, Techno-economic analysis of lithium-ion and lead-acid batteries in stationary energy storage application, J. Energy Storage, 2021, 40, 102748,  DOI:10.1016/j.est.2021.102748.
11. Y. Shi, G. Zhu, X. Guo, Q. Jing, H. Pang and Y. Zhang, Three-dimensional MXene-encapsulated porous Ni-NDC nanosheets as anodes for enhanced lithium-ion batteries, Nano Res., 2023, 16, 2528–2535,  DOI:10.1007/s12274-022-5168-7.
12. Y. Su, L. Chen, Y. Chen, W. Feng, Y. Tian and H. Pang, Low-Temperature Activation of MOF-74 Composite-Derived Materials for Supercapacitors, J. Electron. Mater., 2024, 53, 5797–5802,  DOI:10.1007/s11664-024-11369-2.
13. Y. Zhou, X. Guan, H. Zhou, K. Ramadoss, S. Adam, H. Liu, S. Lee, J. Shi, M. Tsuchiya, D. D. Fong and S. Ramanathan, Strongly correlated perovskite fuel cells, Nature, 2016, 534, 231–234,  DOI:10.1038/nature17653.
14. X. Guo, Q. Peng, K. Shin, Y. Zheng, S. Tunmee, C. Zou, X. Zhou and Y. Tang, Construction of a Composite Sn–DLC Artificial Protective Layer with Hierarchical Interfacial Coupling Based on Gradient Coating Technology Toward Robust Anodes for Zn Metal Batteries, Adv. Energy Mater., 2024, 14, 2402015,  DOI:10.1002/aenm.202402015.
15. X. Guo, W. Li, Q. Zhang, Y. Liu, G. Yuan, P. Braunstein and H. Pang, Ultrasmall metal (Fe, Co, Ni) nanoparticles strengthen silicon oxide embedded nitrogen-doped carbon superstructures for long-cycle-life Li-ion-battery anodes, Chem. Eng. J., 2022, 432, 134413,  DOI:10.1016/j.cej.2021.134413.
16. X. Zhang, Q. Su, G. Du, B. Xu, S. Wang, Z. Chen, L. Wang, W. Huang and H. Pang, Stabilizing Solid–state Lithium Metal Batteries through In Situ Generated Janus–heterarchical LiF–rich SEI in Ionic Liquid Confined 3D MOF/Polymer Membranes, Angew. Chem., Int. Ed., 2023, 62, e202304947,  DOI:10.1002/anie.202304947.
17. C. Wu, H. Huang, W. Lu, Z. Wei, X. Ni, F. Sun, P. Qing, Z. Liu, J. Ma, W. Wei, L. Chen, C. Yan and L. Mai, Mg Doped Li–LiB Alloy with In Situ Formed Lithiophilic LiB Skeleton for Lithium Metal Batteries, Adv. Sci., 2020, 7, 1902643,  DOI:10.1002/advs.201902643.
18. S. Gao, K. Lian, X. Wang, X. Liu, A. Abdukayum, Q. Kong and G. Hu, Recent Achievements in Heterogeneous Bimetallic Atomically Dispersed Catalysts for Zn–Air Batteries: A Minireview, Small, 2024, 20, 2406776,  DOI:10.1002/smll.202406776.
19. L. Ye, M. Liao, K. Zhang, M. Zheng, Y. Jiang, X. Cheng, C. Wang, Q. Xu, C. Tang, P. Li, Y. Wen, Y. Xu, X. Sun, P. Chen, H. Sun, Y. Gao, Y. Zhang, B. Wang, J. Lu, H. Zhou, Y. Wang, Y. Xia, X. Xu and H. Peng, A rechargeable calcium–oxygen battery that operates at room temperature, Nature, 2024, 626, 313–318,  DOI:10.1038/s41586-023-06949-x.
20. W.-X. Hong, W.-H. Wang, Y.-H. Chang, H. Pourzolfaghar, I.-H. Tseng and Y.-Y. Li, A Ni-Fe layered double hydroxide anchored FeCo nanoalloys and Fe-Co dual single-atom electrocatalysts for rechargeable and flexible zinc-air and aluminum-air batteries, Nano Energy, 2024, 121, 109236,  DOI:10.1016/j.nanoen.2023.109236.
21. S. Wang, Y. Su, Z. Jiang, Z. Meng, T. Wang, M. Yang, W. Zhao, H. Chen, M. Shakouri and H. Pang, Metal-Hydroxide Organic Frameworks for Aqueous Nickel-Zinc Batteries, Nano Lett., 2024, 24, 15101–15109,  DOI:10.1021/acs.nanolett.4c04414.
22. Y. Su, Y. Zhang, G. Yuan, Y. Tang, G. Zhang, M. Shakouri, H.-C. Chen, H. Zhou, Z. Liu and H. Pang, Activation of the microstructures in nickel-based bimetallic complexes for aqueous batteries, Sci. China: Chem., 2024 DOI:10.1007/s11426-024-2374-0.
23. M. Zhu, H. Wang, H. Wang, C. Li, D. Chen, K. Wang, Z. Bai, S. Chen, Y. Zhang and Y. Tang, A Fluorinated Solid–state–electrolyte Interface Layer Guiding Fast Zinc–ion Oriented Deposition in Aqueous Zinc–ion Batteries, Angew. Chem., Int. Ed., 2024, 63, e202316904,  DOI:10.1002/anie.202316904.
24. J. Zhou, R. C. K. Reddy, A. Zhong, Y. Li, Q. Huang, X. Lin, J. Qian, C. Yang, I. Manke and R. Chen, Metal–Organic Framework–Based Materials for Advanced Sodium Storage: Development and Anticipation, Adv. Mater., 2024, 36, e2312471,  DOI:10.1002/adma.202312471.
25. Y. Ma, Y. Qi, Y. Niu, Y. Liu, S. Bao and M. Xu, A distinctive conversion mechanism for reversible zinc ion storage, Inorg. Chem. Front., 2022, 9, 2706–2713,  10.1039/D2QI00362G.
26. W. Yang, W. Yang, Y. Huang, C. Xu, L. Dong and X. Peng, Reversible aqueous zinc-ion battery based on ferric vanadate cathode, Chin. Chem. Lett., 2022, 33, 4628–4634,  DOI:10.1016/j.cclet.2021.12.049.
27. W. Sun, F. Wang, S. Hou, C. Yang, X. Fan, Z. Ma, T. Gao, F. Han, R. Hu, M. Zhu and C. Wang, Zn/MnO₂ Battery Chemistry With H⁺ and Zn²⁺ Coinsertion, J. Am. Chem. Soc., 2017, 139, 9775–9778,  DOI:10.1021/jacs.7b04471.
28. L. Yan, X. Zeng, Z. Li, X. Meng, D. Wei, T. Liu, M. Ling, Z. Lin and C. Liang, An innovation: Dendrite free quinone paired with ZnMn₂O₄ for zinc ion storage, Mater. Today Energy, 2019, 13, 323–330,  DOI:10.1016/j.mtener.2019.06.011.
29. F. Chen, Y. Gao, Q. Hao, X. Chen, X. Sun and N. Li, A 2.4 V Aqueous Zinc-Ion Battery Enabled by the Photoelectrochemical Effect of a Modified BiOI Photocathode: Shattering the Shackle of the Electrochemical Window of an Aqueous Electrolyte, ACS Nano, 2024, 18, 6413–6423,  DOI:10.1021/acsnano.3c11851.
30. A. A. Lobinsky and M. V. Kaneva, Layer-by-layer synthesis of Zn-doped MnO₂ nanocrystals as cathode materials for aqueous zinc-ion battery, Nanosyst.:Phys., Chem., Math., 2021, 12, 182–187,  DOI:10.17586/2220-8054-2021-12-2-182-187.
31. A. Zhang, X. Yin, I. Saadoune, Y. Wei and Y. Wang, Zwitterion Intercalated Manganese Dioxide Nanosheets as High–Performance Cathode Materials for Aqueous Zinc Ion Batteries, Small, 2024, 20, 2402811,  DOI:10.1002/smll.202402811.
32. G. Yuan, Y.-Y. Liu, J. Xia, Y. Su, W. Wei, Y. Zhu, Y. An, H. Wu, Q. Xu and H. Pang, Two-dimensional CuO nanosheets-induced MOF composites and derivatives for dendrite-free zinc-ion batteries, Nano Res., 2023, 16, 6881–6889,  DOI:10.1007/s12274-023-5424-x.
33. D. Bi, T. Zhao, Q. Lai, J. Zhao, S. A. Grigoriev and Y. Liang, In situ preparation of MOF-74 for compact zincophilic surfaces enhancing the stability of aqueous zinc-ion battery anodes, J. Alloys Compd., 2024, 1002, 175448,  DOI:10.1016/j.jallcom.2024.175448.
34. W. Zhang, C. Tang, B. Lan, L. Chen, W. Tang, C. Zuo, S. Dong, Q. An and P. Luo, K_0.23V₂O₅ as a promising cathode material for rechargeable aqueous zinc ion batteries with excellent performance, J. Alloys Compd., 2020, 819, 152971,  DOI:10.1016/j.jallcom.2019.152971.
35. Y. Liu, X. Zhou, X. Wang, G. Chen, R. Liu, Y. Ma, Y. Bai and G. Yuan, Hydrated titanic acid as an ultralow-potential anode for aqueous zinc-ion full batteries, Chem. Eng. J., 2021, 420, 129629,  DOI:10.1016/j.cej.2021.129629.
36. X. Li, L. Wang, Y. Fu, H. Dang, D. Wang and F. Ran, Optimization strategies toward advanced aqueous zinc-ion batteries: From facing key issues to viable solutions, Nano Energy, 2023, 116, 108858,  DOI:10.1016/j.nanoen.2023.108858.
37. P. Xu, C. Wang, B. Zhao, Y. Zhou and H. Cheng, An interfacial coating with high corrosion resistance based on halloysite nanotubes for anode protection of zinc-ion batteries, J. Colloid Interface Sci., 2021, 602, 859–867,  DOI:10.1016/j.jcis.2021.06.057.
38. P. Hu, T. Zhu, X. Wang, X. Wei, M. Yan, J. Li, W. Luo, W. Yang, W. Zhang, L. Zhou, Z. Zhou and L. Mai, Highly Durable Na₂V₆O₁₆·1.63H₂O Nanowire Cathode for Aqueous Zinc-Ion Battery, Nano Lett., 2018, 18, 1758–1763,  DOI:10.1021/acs.nanolett.7b04889.
39. N. Wang, K. Ni, H. Liu, R. Cui, J. Gu, X. Fan and D. Wang, A novel high-performance cathode for rechargeable aqueous zinc-ion battery: transformed ZnMnO₃ nanosheets from rhodochrosite MnCO₃ cubes, Funct. Mater. Lett., 2022, 15, 2251039,  DOI:10.1142/S1793604722510390.
40. X. Pu, B. Jiang, X. Wang, W. Liu, L. Dong, F. Kang and C. Xu, High-Performance Aqueous Zinc-Ion Batteries Realized by MOF Materials, Nano-Micro Lett., 2020, 12, 152,  DOI:10.1007/s40820-020-00487-1.
41. L. Lei, F. Chen, Y. Wu, J. Shen, X.-J. Wu, S. Wu and S. Yuan, Surface coatings of two-dimensional metal-organic framework nanosheets enable stable zinc anodes, Sci. China: Chem., 2022, 65, 2205–2213,  DOI:10.1007/s11426-022-1324-0.
42. D. Xu, X. Ren, Y. Xu, Y. Wang, S. Zhang, B. Chen, Z. Chang, A. Pan and H. Zhou, Highly Stable Aqueous Zinc Metal Batteries Enabled by an Ultrathin Crack–Free Hydrophobic Layer with Rigid Sub–Nanochannels, Adv. Sci., 2023, 10, 2303773,  DOI:10.1002/advs.202303773.
43. Y. Liu, L. Wu, P. Zhang, Y. Liu, J. Wu, S. Yao, L. Wang, S. Gong, G. Ju, Z. Yuan and R. Zhang, Modulating the zinc ion flux and electric field intensity by multifunctional metal-organic complex interface layer for highly stable Zn anode, J. Energy Chem., 2024, 99, 375–383,  DOI:10.1016/j.jechem.2024.08.004.
44. K. W. Nam, S. S. Park, R. dos Reis, V. P. Dravid, H. Kim, C. A. Mirkin and J. F. Stoddart, Conductive 2D metal-organic framework for high-performance cathodes in aqueous rechargeable zinc batteries, Nat. Commun., 2019, 10, 4948,  DOI:10.1038/s41467-019-12857-4.
45. Q. Tan, X. Li, B. Zhang, X. Chen, Y. Tian, H. Wan, L. Zhang, L. Miao, C. Wang, Y. Gan, J. Jiang, Y. Wang and H. Wang, Valence Engineering via In Situ Carbon Reduction on Octahedron Sites Mn₃O₄ for Ultra–Long Cycle Life Aqueous Zn–Ion Battery, Adv. Energy Mater., 2020, 10, 2001050,  DOI:10.1002/aenm.202001050.
46. D. Jia, Z. Shen, Y. Lv, Z. Chen, H. Li, Y. Yu, J. Qiu and X. He, In Situ Electrochemical Tuning of MIL–88B(V)@rGO into Amorphous V₂O₅ @rGO as Cathode for High–Performance Aqueous Zinc–Ion Battery, Adv. Funct. Mater., 2024, 34, 2308319,  DOI:10.1002/adfm.202308319.
47. Q. Liu, G. Fan, Y. Zeng, X. Zhang, D. Luan, Y. Guo, X. Gu and X. W. (David) Lou, Hollow Octahedral Pr₆O₁₁−Mn₂O₃ Heterostructures for High–Performance Aqueous Zn–Ion Batteries, Adv. Energy Mater., 2024, 14, 2402743,  DOI:10.1002/aenm.202402743.
48. Y. Shi, B. Yang, G. Song, Z. Chen, M. Shakouri, W. Zhou, X. Zhang, G. Yuan and H. Pang, Ambient Synthesis of Vanadium–Based Prussian Blue Analogues Nanocubes for High–Performance and Durable Aqueous Zinc–Ion Batteries with Eutectic Electrolytes, Angew. Chem., Int. Ed., 2024, 63, e202411579,  DOI:10.1002/anie.202411579.
49. D.-Y. Kang and J. S. Lee, Challenges in Developing MOF-Based Membranes for Gas Separation, Langmuir, 2023, 39, 2871–2880,  DOI:10.1021/acs.langmuir.2c03458.
50. Y. Wang, T. Pan, G. Yuan, Q. Li and H. Pang, MOF and MOF-derived composites for flexible energy storage devices, Compos. Commun., 2024, 52, 102144,  DOI:10.1016/j.coco.2024.102144.
51. D. Fan, A. Ozcan, O. Shekhah, R. Semino, M. Eddaoudi and G. Maurin, Engineering MOF surface defects in mixed matrix membranes: An effective strategy to enhance MOF/polymer adhesion and control interfacial gas transport, J. Membr. Sci. Lett., 2022, 2, 100029,  DOI:10.1016/j.memlet.2022.100029.
52. Q. Li, G. Zhang, Y. Xu, Y. Sun and H. Pang, P-Regulated Hierarchical Structure Ni₂P Assemblies toward Efficient Electrochemical Urea Oxidation, Acta Phys.-Chim. Sin., 2023, 40, 2308045,  DOI:10.3866/PKU.WHXB202308045.
53. M. Yao, J. Xiu, Q. Huang, W. Li, W. Wu, A. Wu, L. Cao, W. Deng, G. Wang and G. Xu, van der Waals Heterostructured MOF–on–MOF Thin Films: Cascading Functionality to Realize Advanced Chemiresistive Sensing, Angew. Chem., Int. Ed., 2019, 58, 14915–14919,  DOI:10.1002/anie.201907772.
54. J. Li, H. Zhao, J. Wang, N. Li, M. Wu, Q. Zhang and Y. Du, Interplanar space-controllable carboxylate pillared metal organic framework ultrathin nanosheet for superhigh capacity rechargeable alkaline battery, Nano Energy, 2019, 62, 876–882,  DOI:10.1016/j.nanoen.2019.06.009.
55. H. Wang, J. Bai, Q. He, Y. Liao and L. Chen, Metal ion and organic ligand disubstituted bimetallic metal–organic framework nanosheets for high-performance alkaline zinc-based batteries, Chem. Commun., 2024, 60, 9590–9593,  10.1039/D4CC02519A.
56. S. Yang, H. Lv, Y. Wang, X. Guo, L. Zhao, H. Li and C. Zhi, Regulating Exposed Facets of Metal–Organic Frameworks for High–rate Alkaline Aqueous Zinc Batteries, Angew. Chem., Int. Ed., 2022, 61, e202209794,  DOI:10.1002/anie.202209794.
57. Z. Ye, Y. Jiang, L. Li, F. Wu and R. Chen, Rational Design of MOF-Based Materials for Next-Generation Rechargeable Batteries, Nano-Micro Lett., 2021, 13, 203,  DOI:10.1007/s40820-021-00726-z.
58. T. Zhao, H. Wu, X. Wen, J. Zhang, H. Tang, Y. Deng, S. Liao and X. Tian, Recent advances in MOFs/MOF derived nanomaterials toward high-efficiency aqueous zinc ion batteries, Coord. Chem. Rev., 2022, 468, 214642,  DOI:10.1016/j.ccr.2022.214642.
59. S. Deng, B. Xu, J. Zhao, C. W. Kan and X. Liu, Unlocking Double Redox Reaction of Metal–Organic Framework for Aqueous Zinc–Ion Battery, Angew. Chem., Int. Ed., 2024, 63, e202401996,  DOI:10.1002/anie.202401996.
60. K. Rambau, N. M. Musyoka, N. Palaniyandy and N. Manyala, Manganese-Based Metal Organic Framework from Spent Li-Ion Batteries and its Electrochemical Performance as Anode Material in Li-ion Battery, J. Electrochem. Soc., 2021, 168, 010527,  DOI:10.1149/1945-7111/abd285.
61. D. D. Khumujam, T. Kshetri, T. I. Singh, S. B. Singh, N. H. Kim and J. H. Lee, Achieving the optimal performance of VO@CoNC anchored on MX/CF through phosphorous-doped induced defects for the fiber-shaped solid-state Zn-ion battery, Chem. Eng. J., 2024, 486, 150252,  DOI:10.1016/j.cej.2024.150252.
62. J. Wang, K. Wang, W. Zhang, J. Zhang, Y. Zhen, F. Fu and Y. Du, Rare earth pillars for stable layered birnessite cathodes propelling aqueous zinc-ion batteries with ultra-long cyclability, Inorg. Chem. Front., 2025, 12, 1002–1009,  10.1039/D4QI02654C.
63. J. Yuan, Y. Gan, J. Mou, X. Ma, X. Li, J. Meng, L. Xu, X. Zhang, H. He and J. Liu, Electrochemically induced amorphous and porous VO_x/N-doped carbon spheres as a cathode for advanced aqueous zinc-ion batteries, Inorg. Chem. Front., 2023, 10, 984–990,  10.1039/D2QI02144G.
64. D. Zhang, W. Wang, S. Li, X. Shen and H. Xu, Design strategies and energy storage mechanisms of MOF-based aqueous zinc ion battery cathode materials, Energy Storage Mater., 2024, 69, 103436,  DOI:10.1016/j.ensm.2024.103436.
65. X. Chen, L. Wang, H. Li, F. Cheng and J. Chen, Porous V₂O₅ nanofibers as cathode materials for rechargeable aqueous zinc-ion batteries, J. Energy Chem., 2019, 38, 20–25,  DOI:10.1016/j.jechem.2018.12.023.
66. X. Hu, F. Zhang, J. Zhong, X. Wang and X. Tong, VO₂-C Cathode Material Prepared from Reduction of V₂O₅ by Citric Acid for Aqueous Zinc Ion Batteries, J. Electrochem. Soc., 2024, 171, 090504,  DOI:10.1149/1945-7111/ad6d00.
67. Y. Liu, J. Zhang, Y. Liu, M. Zhang, Z. Pan and K. Cai, Controllable Design of Metal–Organic Framework–Derived Vanadium Oxynitride for High–Capacity and Long–Cycle Aqueous Zn–Ion Batteries, Small, 2024, 20, 2401922,  DOI:10.1002/smll.202401922.
68. Y. Liu, C. Gao, Y. Sun, X. Hao, Z. Pi, M. Yang, X. Zhao and K. Cai, Enhancing the electrochemical activation kinetics of V₂O₃ for high-performance aqueous zinc-ion battery cathode materials, Chem. Eng. J., 2024, 490, 151535,  DOI:10.1016/j.cej.2024.151535.
69. W. Qian, Z. Chen, L. Chen, Q. Sun, H. Zhou, Z. Zhou, H. Yang and J. Huang, Mixed-valence vanadium oxides with ultra-high rates and long cycles for aqueous zinc ion batteries, Appl. Surf. Sci., 2025, 684, 161981,  DOI:10.1016/j.apsusc.2024.161981.
70. Y. Ru, S. Zheng, H. Xue and H. Pang, Layered V-MOF nanorods for rechargeable aqueous zinc-ion batteries, Mater. Today Chem., 2021, 21, 100513,  DOI:10.1016/j.mtchem.2021.100513.
71. S. Mondal, P. Samanta, R. Sahoo, T. Kuila and M. C. Das, Porous and chemically robust MIL-100(V) MOF as an efficient cathode material for zinc-ion batteries, Chem. Eng. J., 2023, 470, 144340,  DOI:10.1016/j.cej.2023.144340.
72. C. Yin, H. Wang, C. Pan, Z. Li and J. Hu, Constructing MOF-derived V₂O₅ as advanced cathodes for aqueous zinc ion batteries, J. Energy Storage, 2023, 73, 109045,  DOI:10.1016/j.est.2023.109045.
73. B. He, Q. Zhang, P. Man, Z. Zhou, C. Li, Q. Li, L. Xie, X. Wang, H. Pang and Y. Yao, Self-sacrificed synthesis of conductive vanadium-based Metal–Organic framework nanowire-bundle arrays as binder-free cathodes for high-rate and high-energy-density wearable Zn-Ion batteries, Nano Energy, 2019, 64, 103935,  DOI:10.1016/j.nanoen.2019.103935.
74. P. He, Y. Quan, X. Xu, M. Yan, W. Yang, Q. An, L. He and L. Mai, High–Performance Aqueous Zinc–Ion Battery Based on Layered H₂V₃O₈ Nanowire Cathode, Small, 2017, 13, 1702551,  DOI:10.1002/smll.201702551.
75. Y. Liu, J. Huang, X. Li, J. Li, J. Yang and K. Cai, MIL-100(V) derived porous vanadium oxide/carbon microspheres with oxygen defects and intercalated water molecules as high-performance cathode for aqueous zinc ion battery, J. Energy Chem., 2024, 90, 578–589,  DOI:10.1016/j.jechem.2023.11.029.
76. G. Yuan, Y. Su, X. Zhang, B. Gao, J. Hu, Y. Sun, W. Li, Z. Zhang, M. Shakouri and H. Pang, Charged organic ligands inserting/supporting the nanolayer spacing of vanadium oxides for high-stability/efficiency zinc-ion batteries, Natl. Sci. Rev., 2024, 11, nwae336,  DOI:10.1093/nsr/nwae336.
77. M. Zhang, P.-F. Wang, X.-N. Lv, Y. Yang, Y.-H. Zhang, Y.-H. Wu, L. Zhao, G. Yang and F.-N. Shi, Nitrogen-doped carbon/V₂O₃ nanorod composites as cathode material for high-performance aqueous Zn-ion battery, J. Alloys Compd., 2023, 960, 170790,  DOI:10.1016/j.jallcom.2023.170790.
78. K. Hao, Z. Sheng, M. Chen, Y. Lu, P. Qi, G. Liu, H. Wu and Y. Tang, Metal-organic framework-derived self-grown core-shell V₂O₅ for high-performance zinc ion storage, Electrochim. Acta, 2024, 475, 143641,  DOI:10.1016/j.electacta.2023.143641.
79. N. Yu, M. Li, X. Chen, L. Xu, W. Wang, F. Wei, Y. Sui, Q. Yan and S. Wang, Controllable Synthesis of Skeletonized V₂O₅ Microspheres Derived from a V-MOF for Aqueous Zinc-Ion Batteries, ACS Appl. Energy Mater., 2023, 6, 12043–12051,  DOI:10.1021/acsaem.3c02271.
80. W. Zhou, J. Chen, M. Chen, X. Xu, Q. Tian, J. Xu and C.-P. Wong, Rod-like anhydrous V₂O₅ assembled by tiny nanosheets as a high-performance cathode material for aqueous zinc-ion batteries, RSC Adv., 2019, 9, 30556–30564,  10.1039/C9RA06143F.
81. S. Deng, Z. Yuan, Z. Tie, C. Wang, L. Song and Z. Niu, Electrochemically Induced Metal–Organic–Framework–Derived Amorphous V₂O₅ for Superior Rate Aqueous Zinc–Ion Batteries, Angew. Chem., Int. Ed., 2020, 59, 22002–22006,  DOI:10.1002/anie.202010287.
82. Y. Zhang, S. Jiang, Y. Li, X. Ren, P. Zhang, L. Sun and H. Y. Yang, In Situ Grown Hierarchical Electrospun Nanofiber Skeletons with Embedded Vanadium Nitride Nanograins for Ultra–Fast and Super–Long Cycle Life Aqueous Zn–Ion Batteries, Adv. Energy Mater., 2023, 13, 2202826,  DOI:10.1002/aenm.202202826.
83. J. Li, W. Shao, D. Zhang and Q. Wang, Copper-doped layered Fe₂VO₄ nanorods for aqueous zinc-ion batteries, J. Colloid Interface Sci., 2023, 652, 500–507,  DOI:10.1016/j.jcis.2023.08.085.
84. Y. Liu and X. Wu, Metal-organic framework assisted design of ZnVO_x cathode for aqueous zinc batteries at extreme work condition, Nano Energy, 2024, 127, 109809,  DOI:10.1016/j.nanoen.2024.109809.
85. Y. Du, Y. Xu, Y. Zhang, B. Yang, H. Lu, C. Ge and D. Bin, Metal-organic-framework-derived cobalt-vanadium oxides with tunable compositions for high-performance aqueous zinc-ion batteries, Chem. Eng. J., 2023, 457, 141162,  DOI:10.1016/j.cej.2022.141162.
86. D. Wang, C. Wen, B. Zhang, G. Zhu, W. Wen, Q. Liu, M. Xu, P. Ling and Z. Zhou, In situ thermal conversion strategy derived from metal-organic framework for enhanced cathode performance in aqueous zinc-ion batteries, J. Energy Storage, 2024, 95, 112596,  DOI:10.1016/j.est.2024.112596.
87. K. Ran, Q. Chen, F. Song and F. Yang, Defective construction of vanadium-based cathode materials for high-rate long-cycle aqueous zinc ion batteries, J. Colloid Interface Sci., 2024, 653, 673–686,  DOI:10.1016/j.jcis.2023.09.102.
88. Y. Liu, T. Wang, Y. Sun, M. Zhang, G. Gao, J. Yang and K. Cai, Fast and efficient in situ construction of low crystalline PEDOT-intercalated V₂O₅ nanosheets for high-performance zinc-ion battery, Chem. Eng. J., 2024, 484, 149501,  DOI:10.1016/j.cej.2024.149501.
89. Y. Zhang, Z. Li, M. Liu and J. Liu, Construction of novel polyaniline-intercalated hierarchical porous V₂O₅ nanobelts with enhanced diffusion kinetics and ultra-stable cyclability for aqueous zinc-ion batteries, Chem. Eng. J., 2023, 463, 142425,  DOI:10.1016/j.cej.2023.142425.
90. M. Chen, J. Ma, Y. Feng, Q. Yuan, Y. Wu, Y. Liu, G. Hu and X. Liu, Advancing aqueous zinc-ion batteries with carbon dots: A comprehensive review, EcoEnergy, 2024 DOI:10.1002/ece2.83.
91. Y. Li, H. Liu, M. Ma, W. Peng, Y. Li and X. Fan, N-Doping-Induced Amorphization for Achieving Ultrastable Aqueous Zinc-Ion Batteries, ACS Appl. Mater. Interfaces, 2024, 16, 26079–26087,  DOI:10.1021/acsami.4c01360.
92. Q. Wang, T. Sun, S. Zheng, L. Li, T. Ma and J. Liang, A new tunnel-type V₄O₉ cathode for high power density aqueous zinc ion batteries, Inorg. Chem. Front., 2021, 8, 4497–4506,  10.1039/D1QI00747E.
93. L. Chen, Y. Zheng, Z. Zhang, Y. Ma, Y. Wang, H. Xiao, M. Xu, Z. Li and G. Yuan, Optimizing ammonium vanadate crystal structure by facile in situ phase transformation of VO₂/NH₄ V₄O₁₀ with special micro–nano feature for advanced aqueous zinc ion batteries, Inorg. Chem. Front., 2024, 11, 1266–1278,  10.1039/D3QI02266H.
94. Y. Lin, F. Zhou, M. Chen, S. Zhang and C. Deng, Building defect-rich oxide nanowires@graphene coaxial scrolls to boost high-rate capability, cycling durability and energy density for flexible Zn-ion batteries, Chem. Eng. J., 2020, 396, 125259,  DOI:10.1016/j.cej.2020.125259.
95. T. Lv, G. Zhu, S. Dong, Q. Kong, Y. Peng, S. Jiang, G. Zhang, Z. Yang, S. Yang, X. Dong, H. Pang and Y. Zhang, Co–Intercalation of Dual Charge Carriers in Metal–Ion–Confining Layered Vanadium Oxide Nanobelts for Aqueous Zinc–Ion Batteries, Angew. Chem., Int. Ed., 2023, 62, e202216089,  DOI:10.1002/ange.202216089.
96. J. Zeng, K. Chao, W. Wang, X. Wei, C. Liu, H. Peng, Z. Zhang, X. Guo and G. Li, Silver vanadium oxide@water-pillared vanadium oxide coaxial nanocables for superior zinc ion storage properties, Inorg. Chem. Front., 2019, 6, 2339–2348,  10.1039/C9QI00559E.
97. Y. Tong, Y. Zhao, M. Luo, S. Su, Y. Yang, Y. Zang, X. Li, L. Wang and J. Fang, MOF-derived heterostructured C@VO₂ @V₂O₅ for stable aqueous zinc-ion batteries cathode, J. Alloys Compd., 2023, 932, 167681,  DOI:10.1016/j.jallcom.2022.167681.
98. S. Deng, Z. Yuan, Z. Tie, C. Wang, L. Song and Z. Niu, Electrochemically Induced Metal–Organic–Framework–Derived Amorphous V₂O₅ for Superior Rate Aqueous Zinc–Ion Batteries, Angew. Chem., 2020, 132, 22186–22190,  DOI:10.1002/ange.202010287.
99. T. He, J. Li, Z. Luo, Y. Zhang, Y. Zhao, X. Zhang and Y. Chen, MIL–47(V) Derived V₂O₅ @Carbon Core–Shell Microcuboids with Oxygen Vacancies as Advanced Conversion Cathodes for High–Performance Zinc–Ion Batteries, ChemElectroChem, 2022, 9, e202200178,  DOI:10.1002/celc.202200178.
100. R. Fang, K. Chen, L. Yin, Z. Sun, F. Li and H. Cheng, The Regulating Role of Carbon Nanotubes and Graphene in Lithium–Ion and Lithium–Sulfur Batteries, Adv. Mater., 2019, 31, 1800863,  DOI:10.1002/adma.201800863.
101. Y. Cai, F. Liu, Z. Luo, G. Fang, J. Zhou, A. Pan and S. Liang, Pilotaxitic Na_1.1V₃O_7.9 nanoribbons/graphene as high-performance sodium ion battery and aqueous zinc ion battery cathode, Energy Storage Mater., 2018, 13, 168–174,  DOI:10.1016/j.ensm.2018.01.009.
102. Y. Zhang, Z. Li, L. Gong and J. Liu, Facile Construction of the Graphene-Supported Porous V₂O₃ Nanocomposite Derived from the V-MOF@Graphene Precursor with Enhanced Performance for Aqueous Zinc-Ion Batteries, ACS Appl. Energy Mater., 2022, 5, 14990–14999,  DOI:10.1021/acsaem.2c02532.
103. S. Kong, Y. Feng, Z. Xu, X. Wang, X. Zhang, X. Lan, Z. Ma, Y. Yao, Z. Yong and Q. Li, Constructing metal-organic framework-derived carbon incorporated V₂O₅ nanowire-bundle arrays on carbon nanotube fiber as advanced cathodes for high-performance wearable zinc-ion batteries, Electrochim. Acta, 2023, 440, 141762,  DOI:10.1016/j.electacta.2022.141762.
104. Y. Han, H. Duan, C. Zhou, H. Meng, Q. Jiang, B. Wang, W. Yan and R. Zhang, Stabilizing Cobalt Single Atoms via Flexible Carbon Membranes as Bifunctional Electrocatalysts for Binder-Free Zinc–Air Batteries, Nano Lett., 2022, 22, 2497–2505,  DOI:10.1021/acs.nanolett.2c00278.
105. W. Wang, C. Li, S. Liu, J. Zhang, D. Zhang, J. Du, Q. Zhang and Y. Yao, Flexible Quasi–Solid–State Aqueous Zinc–Ion Batteries: Design Principles, Functionalization Strategies, and Applications, Adv. Energy Mater., 2023, 13, 2300250,  DOI:10.1002/aenm.202300250.
106. M. Liu, Z. Li and Y. Zhang, V-MOF@carbon nanotube derived three-dimensional V₂O₅@carbon nanotube as high-performance cathode for aqueous zinc-ion batteries, J. Electroanal. Chem., 2023, 942, 117576,  DOI:10.1016/j.jelechem.2023.117576.
107. M. Narayanasamy, B. Kirubasankar, M. Shi, S. Velayutham, B. Wang, S. Angaiah and C. Yan, Morphology restrained growth of V₂O₅ by the oxidation of V-MXenes as a fast diffusion controlled cathode material for aqueous zinc ion batteries, Chem. Commun., 2020, 56, 6412–6415,  10.1039/D0CC01802C.
108. T. Wang, P. Liu, X. Chen, Y. Guo, C. He, J. Guo, W. Liu, S. Gao, Y. Lv and K. Liu, Enhancing aqueous zinc-ion energy storage performance with ion-mediating carbon quantum dots-modified separators regulating zinc deposition behavior, J. Colloid Interface Sci., 2025, 678, 301–310,  DOI:10.1016/j.jcis.2024.08.175.
109. M. Abouali, S. Adhami, S. A. Haris and R. Yuksel, On the Dendrite–Suppressing Effect of Laser–Processed Polylactic Acid–Derived Carbon Coated Zinc Anode in Aqueous Zinc Ion Batteries, Angew. Chem., Int. Ed., 2024, 63, e202405048,  DOI:10.1002/anie.202405048.
110. Y. Tan, S. Li, X. Zhao, Y. Wang, Q. Shen, X. Qu, Y. Liu and L. Jiao, Unexpected Role of the Interlayer “Dead Zn²⁺” in Strengthening the Nanostructures of VS₂ Cathodes for High–Performance Aqueous Zn–Ion Storage, Adv. Energy Mater., 2022, 12, 2104001,  DOI:10.1002/aenm.202104001.
111. F. Ming, H. Liang, Y. Lei, S. Kandambeth, M. Eddaoudi and H. N. Alshareef, Layered Mg_xV₂O₅·nH₂O as Cathode Material for High-Performance Aqueous Zinc Ion Batteries, ACS Energy Lett., 2018, 3, 2602–2609,  DOI:10.1021/acsenergylett.8b01423.
112. M. Niu, W. Xin, L. Zhang, M. Yang, Y. Geng, X. Xiao, H. Zhang and Z. Zhu, Selenium doping induced phase transformation and interlayer expansion boost the zinc storage performance of molybdenum disulfide, Inorg. Chem. Front., 2024, 11, 2272–2280,  10.1039/D4QI00344F.
113. Z. Fang, Y. Tong, Y. Yang, A. Hu, J. Long, Y. Zhao, X. Lai, D. Gao and M. Liu, Dual effects of Ag⁺ intercalation boosting the kinetics and stability of NH₄V₄O₁₀ cathodes for enhanced zinc ion storage, Inorg. Chem. Front., 2024, 11, 8855–8865,  10.1039/D4QI01942C.
114. M. Liu, Z. Li and Y. Zhang, K-doped V₂O₅ derived from V-MOF precursor as high-performance cathode for aqueous zinc-ion batteries, J. Electroanal. Chem., 2023, 942, 117539,  DOI:10.1016/j.jelechem.2023.117539.
115. Y. Zhang, X. Li, Y. Cheng, W. Tan and X. Huang, Binder-free Cu-supported Ag nanowires for aqueous rechargeable silver-zinc batteries with ultrahigh areal capacity, J. Colloid Interface Sci., 2021, 586, 47–55,  DOI:10.1016/j.jcis.2020.10.068.
116. X. Wu, L. Luo, S. Peng, M. Zhang, X. Li, X. Meng, C. Yin, X. Wu and X. Wu, A universal fabrication strategy for MOFs-driven vanadium-based composite for aqueous zinc ion batteries, Chem. Eng. J., 2024, 482, 148836,  DOI:10.1016/j.cej.2024.148836.
117. Y. Zhang, B. Zhao, Z. Li, Z. Guo and M. Liu, Ce ions intercalation and structural engineering assist MOF-derived porous V₂O₅ with enhanced Zn²⁺ diffusion kinetics for high-rate and ultra-stable aqueous zinc-ion batteries, Mater. Today Chem., 2024, 36, 101946,  DOI:10.1016/j.mtchem.2024.101946.
118. Y. Huo, Y. Teng, K. Cai and H. Chen, Honeycomb ZnO/N/C obtained from cornsilk and ZIF-8 dual induced method for long-life aqueous zinc-ion batteries, J. Alloys Compd., 2021, 855, 157398,  DOI:10.1016/j.jallcom.2020.157398.
119. B. Dai, X. Shen, T. Chen, J. Li and Q. Xu, Porous layered ZnV₂O₄@C synthesized based on a bimetallic MOF as a stable cathode material for aqueous zinc ion batteries, Dalton Trans., 2024, 53, 8335–8346,  10.1039/D4DT01062K.
120. H. Jiang, W. Gong, Y. Zhang, X. Liu, M. Waqar, J. Sun, Y. Liu, X. Dong, C. Meng, Z. Pan and J. Wang, Quench-tailored Al-doped V₂O₅ nanomaterials for efficient aqueous zinc-ion batteries, J. Energy Chem., 2022, 70, 52–58,  DOI:10.1016/j.jechem.2022.02.030.
121. F. Wan and Z. Niu, Design Strategies for Vanadium–based Aqueous Zinc–Ion Batteries, Angew. Chem., Int. Ed., 2019, 58, 16358–16367,  DOI:10.1002/anie.201903941.
122. C. Lv, L. Bao, Y. Huo, Y. Liu and Z. Su, Enhancing the hydrogen ion adsorption capacity to improve the performance of an aqueous zinc ion battery of V₂O₅, Inorg. Chem. Commun., 2024, 161, 112053,  DOI:10.1016/j.inoche.2024.112053.
123. Y. Li, Z. Huang, P. K. Kalambate, Y. Zhong, Z. Huang, M. Xie, Y. Shen and Y. Huang, V₂O₅ nanopaper as a cathode material with high capacity and long cycle life for rechargeable aqueous zinc-ion battery, Nano Energy, 2019, 60, 752–759,  DOI:10.1016/j.nanoen.2019.04.009.
124. G. Zhang, L. Jin, R. Zhang, Y. Bai, R. Zhu and H. Pang, Recent advances in the development of electronically and ionically conductive metal-organic frameworks, Coord. Chem. Rev., 2021, 439, 213915,  DOI:10.1016/j.ccr.2021.213915.
125. P. Geng, M. Du, C. Wu, T. Luo, Y. Zhang and H. Pang, PPy-constructed core–shell structures from MOFs for confining lithium polysulfides, Inorg. Chem. Front., 2022, 9, 2389–2394,  10.1039/D2QI00392A.
126. J. Sun, M. Rong, Z. Gao, Z. Feng, Y. Liu, T. Hu, C. Meng and Y. Zhang, Poly(3,4-ethylenedioxythiophene) encapsulating hydrated vanadium oxide nanobelts boosts their conductivity and zinc-ion storage properties, Inorg. Chem. Front., 2023, 10, 4266–4275,  10.1039/D3QI00781B.
127. S. Zhao, G. Tian, D. Zhang and Q. Wang, Controlled Synthesis of Metal–Organic-Framework-Derived V₂O₅ Nanostructures with Polypyrrole Coating for Zinc-Ion Batteries, ACS Appl. Nano Mater., 2023, 6, 1849–1858,  DOI:10.1021/acsanm.2c04836.
128. J. Han, Z. Chen, J. Xu and J. Han, A novel electrolyte study on polyaniline aqueous zinc-ion battery, Mater. Lett., 2021, 304, 130629,  DOI:10.1016/j.matlet.2021.130629.
129. S. Li, X. Wei, C. Wu, B. Zhang, S. Wu and Z. Lin, Constructing Three-Dimensional Structured V₂O₅/Conductive Polymer Composite with Fast Ion/Electron Transfer Kinetics for Aqueous Zinc-Ion Battery, ACS Appl. Energy Mater., 2021, 4, 4208–4216,  DOI:10.1021/acsaem.1c00573.
130. S. Chen, K. Li, K. S. Hui and J. Zhang, Regulation of Lamellar Structure of Vanadium Oxide via Polyaniline Intercalation for High–Performance Aqueous Zinc–Ion Battery, Adv. Funct. Mater., 2020, 30, 2003890,  DOI:10.1002/adfm.202003890.
131. M. Li, C. Liu, J. Meng, P. Hei, Y. Sai, W. Li, J. Wang, W. Cui, Y. Song and X. Liu, Hydroxylated Manganese Oxide Cathode for Stable Aqueous Zinc–Ion Batteries, Adv. Funct. Mater., 2024, 30, 2405659,  DOI:10.1002/adfm.202405659.
132. S. Xu, S. Fan, W. Ma, J. Fan and G. Li, Electrochemical reaction behavior of MnS in aqueous zinc ion battery, Inorg. Chem. Front., 2022, 9, 1481–1489,  10.1039/D1QI01659H.
133. S. Liu, J. Wang, Z. Zhou, Y. Li, W. Zhang and C. Wang, Cobalt-doped δ-MnO₂/CNT composites as cathode material for aqueous zinc-ion batteries, Inorg. Chem. Front., 2023, 10, 5167–5177,  10.1039/D3QI01010D.
134. D. Qin, J. Ding, C. Liang, Q. Liu, L. Feng, Y. Luo, G. Hu, J. Luo and X. Liu, Addressing Challenges and Enhancing Performance of Manganese-based Cathode Materials in Aqueous Zinc-Ion Batteries, Acta Phys.-Chim. Sin., 2024, 40, 2310034,  DOI:10.3866/PKU.WHXB202310034.
135. C. Chen, M. Shi, Y. Zhao, C. Yang, L. Zhao and C. Yan, Al-Intercalated MnO₂ cathode with reversible phase transition for aqueous Zn-Ion batteries, Chem. Eng. J., 2021, 422, 130375,  DOI:10.1016/j.cej.2021.130375.
136. M. Shi, B. Wang, Y. Shen, J. Jiang, W. Zhu, Y. Su, M. Narayanasamy, S. Angaiah, C. Yan and Q. Peng, 3D assembly of MXene-stabilized spinel ZnMn₂O₄ for highly durable aqueous zinc-ion batteries, Chem. Eng. J., 2020, 399, 125627,  DOI:10.1016/j.cej.2020.125627.
137. S. Jiang, W. Han, L. Fang, S. Zhang, X. Xue, P. Nie, B. Liu, C. Zhao, M. Lu and L. Chang, Achieving Non–Interfacial Blocking Zinc Ion Transport Based on MOF Derived Manganese Oxides and Amorphous Carbon Hybrid Materials, Chem. – Eur. J., 2024, 30, e202401802,  DOI:10.1002/chem.202401802.
138. L. Li, S. Jia, Y. Shi, Y. Yang, C. Tan, C. Wang, H. Qiu, Y. Ji, M. Cao and D. Zhang, The spatial and electronic effects of polypyrrole between MnO₂ layers enhance the diffusion ability of Zn²⁺ ions, Inorg. Chem. Front., 2025, 12, 596–607,  10.1039/D4QI02739F.
139. L. Qin, Q. Zhu, L. Li, H. Cheng, W. Li, Z. Fang, M. Mo and S. Chen, Ni²⁺-doped ZnMn₂O₄ with enhanced electrochemical performance as cathode material for aqueous zinc-ion batteries, J. Solid State Electrochem., 2023, 27, 773–784,  DOI:10.1007/s10008-022-05370-0.
140. C. Yin, C. Pan, X. Liao, Y. Pan and L. Yuan, Coordinately Unsaturated Manganese-Based Metal–Organic Frameworks as a High-Performance Cathode for Aqueous Zinc-Ion Batteries, ACS Appl. Mater. Interfaces, 2021, 13, 35837–35847,  DOI:10.1021/acsami.1c10063.
141. J. Zhang, Y. Liu, T. Wang, N. Fu and Z. Yang, Manganese-based MOF interconnected carbon nanotubes as a high-performance cathode for rechargeable aqueous zinc-ion batteries, J. Energy Storage, 2024, 76, 109873,  DOI:10.1016/j.est.2023.109873.
142. S. Deng, Z. Tie, F. Yue, H. Cao, M. Yao and Z. Niu, Rational Design of ZnMn₂O₄ Quantum Dots in a Carbon Framework for Durable Aqueous Zinc–Ion Batteries, Angew. Chem., Int. Ed., 2022, 61, e202115877,  DOI:10.1002/anie.202115877.
143. Z. Zhang, C. Tang, K. Zhang, H. Li, J. Cao, Z. Shao and J. Gong, Synthesis of Mn(OH)₂ Nanosheets on Carbon Cloth for High-Performance Aqueous Zinc-Ion Battery, J. Nanoelectron. Optoelectron., 2021, 16, 1698–1704,  DOI:10.1166/jno.2021.3131.
144. Y. Hu, H. Li, H. Gu, L. Chen, W. Zhang and Z. Li, Unlocking the potential of cation vacancy-enriched ZnMn_1.75O₄ cathode for advanced aqueous aluminum-ion batteries, Energy Storage Mater., 2024, 71, 103690,  DOI:10.1016/j.ensm.2024.103690.
145. N. Zhang, F. Cheng, J. Liu, L. Wang, X. Long, X. Liu, F. Li and J. Chen, Rechargeable aqueous zinc-manganese dioxide batteries with high energy and power densities, Nat. Commun., 2017, 8, 405,  DOI:10.1038/s41467-017-00467-x.
146. C. Bischoff, O. Fitz, C. Schiller, H. Gentischer, D. Biro and H.-M. Henning, Investigating the Impact of Particle Size on the Performance and Internal Resistance of Aqueous Zinc Ion Batteries with a Manganese Sesquioxide Cathode, Batteries, 2018, 4, 44,  DOI:10.3390/batteries4030044.
147. M. Mao, X. Wu, Y. Hu, Q. Yuan, Y.-B. He and F. Kang, Charge storage mechanism of MOF-derived Mn₂O₃ as high performance cathode of aqueous zinc-ion batteries, J. Energy Chem., 2021, 52, 277–283,  DOI:10.1016/j.jechem.2020.04.061.
148. J. W. Wang, Y. F. Yuan, D. Zhang, M. Zhu, C. L. Mo and S. Y. Guo, Constructing metal-organic framework-derived Mn₂O₃ multishelled hollow nanospheres for high-performance cathode of aqueous zinc-ion batteries, Nanotechnology, 2021, 32, 435401,  DOI:10.1088/1361-6528/ac15cb.
149. C. Yin, C. Pan, Y. Pan and J. Hu, Hierarchical spheroidal MOF-derived MnO@C as cathode components for high-performance aqueous zinc ion batteries, J. Colloid Interface Sci., 2023, 642, 513–522,  DOI:10.1016/j.jcis.2023.03.186.
150. X. Xu, Y. Chen, W. Li, R. Yin, D. Zheng, X. Niu, X. Dai, W. Shi, W. Liu, F. Wu, M. Wu, S. Lu and X. Cao, Achieving Ultralong–Cycle Zinc–Ion Battery via Synergistically Electronic and Structural Regulation of a MnO₂ Nanocrystal–Carbon Hybrid Framework, Small, 2023, 19, 2207517,  DOI:10.1002/smll.202207517.
151. C. Yin, J. Chen, C.-L. Pan, Y. Pan and J. Hu, MOF-Derived Mn₃O₄@C Hierarchical Nanospheres as Cathodes for Aqueous Zinc-Ion Batteries, ACS Appl. Energy Mater., 2022, 5, 14144–14154,  DOI:10.1021/acsaem.2c02690.
152. C. Liu, Q. Li, H. Sun, Z. Wang, W. Gong, S. Cong, Y. Yao and Z. Zhao, MOF-derived vertically stacked Mn₂O₃@C flakes for fiber-shaped zinc-ion batteries, J. Mater. Chem. A, 2020, 8, 24031–24039,  10.1039/D0TA09212F.
153. X. Guo, C. Li, X. Wang, Z. Li, H. Zeng, P. Hou, M. Xie, Y. Li, Z. Shi and S. Feng, Rational design of interfacial bonds within dual carbon-protected manganese oxide towards durable aqueous zinc ion battery, Sci. China: Chem., 2023, 66, 1406–1416,  DOI:10.1007/s11426-022-1522-x.
154. B. Wang, W. Li, S. Wang, P. Xie, P. Wan, Y. Gui and D. Chen, Rationally designed carbon-encapsulated manganese selenide composites from metal–organic frameworks for stable aqueous Zn–Mn batteries, J. Mater. Chem. A, 2024, 12, 6549–6560,  10.1039/D3TA08043A.
155. J. Bai, S. Hu, L. Feng, X. Jin, D. Wang, K. Zhang and X. Guo, Manganese vanadium oxide composite as a cathode for high-performance aqueous zinc-ion batteries, Chin. Chem. Lett., 2024, 35, 109326,  DOI:10.1016/j.cclet.2023.109326.
156. Y. Chen, X. Hu, X. Chen, J.-H. Liu, Y. Huang and D. Cao, Trimetallic-Organic Framework-Derived Ni-Doped MnO/PC as cathodes for High-Performance aqueous zinc-ion batteries, Chem. Eng. J., 2023, 478, 147411,  DOI:10.1016/j.cej.2023.147411.
157. M. Bai, S. Li, C. Zhang, Y. Liu, Z. Wen and J. Sun, Novel composite cathode material α-MnO₂@ZIF-67 for high performance aqueous rechargeable Zn-ion battery, J. Electroanal. Chem., 2024, 957, 118104,  DOI:10.1016/j.jelechem.2024.118104.
158. W. Zhang, Y. Zou, H. Zhao, M. Chen, L. Zhou, X. Xie, X. Yan, H. Pang and Z. Gu, Double–Shelled Open Hollow Metal–Organic Frameworks for Efficient Aqueous Zn–Ion Batteries, Small, 2024, 20, 2307809,  DOI:10.1002/smll.202307809.
159. Y. Yuan, J. Ma, C. Ma, X. Zhou and Y. Zhou, Multifactor induction of pseudocapacitive in manganese oxide cathode enabling high-performance aqueous zinc ion batteries, J. Energy Storage, 2025, 105, 114595,  DOI:10.1016/j.est.2024.114595.
160. J. Baek, S. Kim, Y. Ahn, Y. Seo, J. Yoo, D. Lee and S. Byun, Impact of carbon additives on alpha-MnO₂ cathode performance in aqueous zinc ion batteries: Towards high energy density and stability, J. Energy Storage, 2025, 107, 114922,  DOI:10.1016/j.est.2024.114922.
161. Y. Li, F. Zhang, M. Wu, Y. Guo, Y. Liang, R. Ababaikeri, L. Wang, Q. Liu and X. Wang, In situ growth of δ-MnO₂ /C fibers as a binder-free and free-standing cathode for advanced aqueous Zn-ion batteries, Inorg. Chem. Front., 2024, 11, 8016–8024,  10.1039/D4QI01661K.
162. K. Sun, J. Pang, Y. Zheng, F. Xing, R. Jiang, J. Min, J. Ye, L. Wang, Y. Luo, T. Gu and L. Chen, Oxygen vacancies enriched MOF-derived MnO/C hybrids for high-performance aqueous zinc ion battery, J. Alloys Compd., 2022, 923, 166470,  DOI:10.1016/j.jallcom.2022.166470.
163. M. Yang, R. Chen, Y. Shen, X. Zhao and X. Shen, A High–Energy Aqueous Manganese–Metal Hydride Hybrid Battery, Adv. Mater., 2020, 32, 2001106,  DOI:10.1002/adma.202001106.
164. Y. Zhang, Y. Du, B. Song, Z. Wang, X. Wang, F. Wan and X. Ma, Manganese-ions and polyaniline co-intercalation into vanadium oxide for stable zinc-ion batteries, J. Power Sources, 2022, 545, 231920,  DOI:10.1016/j.jpowsour.2022.231920.
165. Y. Xia, T. S. Mathis, M.-Q. Zhao, B. Anasori, A. Dang, Z. Zhou, H. Cho, Y. Gogotsi and S. Yang, Thickness-independent capacitance of vertically aligned liquid-crystalline MXenes, Nature, 2018, 557, 409–412,  DOI:10.1038/s41586-018-0109-z.
166. C. Liu, J. Zhou, J. Song, D. Tian, Y. Xu and L. Li, Application of cobalt-modified irregular cubic block–shaped MnCO₃@Mn₃N₂@Mn₂O₃ composite cathode material in aqueous zinc-ion batteries, Ionics, 2024, 30, 8159–8173,  DOI:10.1007/s11581-024-05842-5.
167. D. Jia, Z. Yang, W. Gu and X. Liu, Manganese-based metal-organic-framework derived hydrophilic cathode with carbon nanotubes introduced for long-life and high-performance aqueous zinc-ion battery, J. Alloys Compd., 2022, 910, 164876,  DOI:10.1016/j.jallcom.2022.164876.
168. X. Dong, J. Sun, Y. Mu, Y. Yu, T. Hu, C. Miao, C. Huang, C. Meng and Y. Zhang, RGO/Manganese Silicate/MOF-derived carbon Double-Sandwich-Like structure as the cathode material for aqueous rechargeable Zn-ion batteries, J. Colloid Interface Sci., 2022, 610, 805–817,  DOI:10.1016/j.jcis.2021.11.137.
169. J. Huang, J. Zeng, K. Zhu, R. Zhang and J. Liu, High-Performance Aqueous Zinc–Manganese Battery with Reversible Mn²⁺/Mn⁴⁺ Double Redox Achieved by Carbon Coated MnO_x Nanoparticles, Nano-Micro Lett., 2020, 12, 110,  DOI:10.1007/s40820-020-00445-x.
170. L. Dai, Y. Wang, L. Sun, Y. Ding, Y. Yao, L. Yao, N. E. Drewett, W. Zhang, J. Tang and W. Zheng, Jahn–Teller Distortion Induced Mn²⁺–Rich Cathode Enables Optimal Flexible Aqueous High–Voltage Zn–Mn Batteries, Adv. Sci., 2021, 8, 2004995,  DOI:10.1002/advs.202004995.
171. C. Li, M. Li, H. Xu, F. Zhao, S. Gong, H. Wang, J. Qi, Z. Wang, Y. Hu, W. Peng, X. Fan and J. Liu, Hierarchical accordion-like manganese oxide@carbon hybrid with strong interaction heterointerface for high-performance aqueous zinc ion batteries, J. Colloid Interface Sci., 2022, 628, 553–561,  DOI:10.1016/j.jcis.2022.07.179.
172. T. Chen, X. Shen, B. Dai and Q. Xu, Layered porous Mn_0.18V₂O₅@C with manganese and carbon provided by a metal–organic framework precursor as a cathode material for aqueous zinc-ion batteries, Dalton Trans., 2023, 52, 13797–13807,  10.1039/D3DT02152A.
173. R. Zhu, Y. Xu, L. Liu, Y. Jiang, Y. Gu and H. Pang, Bimetallic MOF-oriented battery materials: A new direction on cathode, anode, and separator, Chem. Eng. J., 2024, 499, 156303,  DOI:10.1016/j.cej.2024.156303.
174. W. Leng, L. Cui, Y. Liu and Y. Gong, MOF–Derived MnV₂O₄/C Microparticles with Graphene Coating Anchored on Graphite Sheets: Oxygen Defect Engaged High Performance Aqueous Zinc–Ion Battery, Adv. Mater. Interfaces, 2022, 9, 2101705,  DOI:10.1002/admi.202101705.
175. Y. Zou, Z. Guo, J. Zhou, Q. Zheng, X. Shan and L. Zhao, One-pot preparation of La(OH)₃ nanoparticles and NiMn LDH nanosheets with mutual support structure as cathode for high-performance aqueous zinc-ion batteries, J. Alloys Compd., 2022, 918, 165547,  DOI:10.1016/j.jallcom.2022.165547.
176. J. Li, X. Yang, J. Wang, C. Ma, T. Wang, N. Liu, X. Pang, Q. Zhang, C. Wu and X. Li, Highly efficient Mn²⁺ deposition induced by H-vacancies of NiMn-LDH nanosheets for durable zinc ion batteries, Energy Storage Mater., 2025, 74, 103887,  DOI:10.1016/j.ensm.2024.103887.
177. D. Van Lam, D. T. Dung, J.-H. Kim and S.-M. Lee, Metal–Organic Framework-Derived NiO@C as a Host for MnO₂ Cathode of Stable Zinc-Ion Batteries, ACS Appl. Energy Mater., 2023, 6, 5368–5377,  DOI:10.1021/acsaem.3c00398.
178. S. Luo, J. Xu, B. Yuan, L. Chen, L. Xu, R. Zheng, Y. Wang, M. Zhang, Y. Lu and Y. Luo, Honeycomb-like δ-MnO₂/NCP integrated cathode for advanced aqueous zinc-ion batteries, Electrochim. Acta, 2023, 468, 143192,  DOI:10.1016/j.electacta.2023.143192.
179. B. Ma, Y. Zhang, Y. Feng, S. Wang, Y. Wang and W. Zhang, Bimetallic MOF-derived manganese-cobalt composite oxide as high-performance zinc-ion batteries cathode, J. Solid State Electrochem., 2024, 29, 239–248,  DOI:10.1007/s10008-024-06050-x.
180. M. Wu, J. Duan, M. Chen and C. Wang, High-cycling Stability of Zn/MnHCF Batteries Boosted by Non-aqueous Ethanol Electrolyte, Chem. Lett., 2022, 51, 993–996,  DOI:10.1246/cl.220308.
181. B. Purusottam Reddy, P. Reddy Prasad, K. Mallikarjuna, M. Chandra Sekhar, Y.-W. Lee, Y. Suh and S.-H. Park, Mn–Co Prussian blue analogue cubic frames for efficient aqueous Zn ion batteries, Microporous Mesoporous Mater., 2023, 362, 112793,  DOI:10.1016/j.micromeso.2023.112793.
182. M. S. Chae, J. W. Heo, H. H. Kwak, H. Lee and S.-T. Hong, Organic electrolyte-based rechargeable zinc-ion batteries using potassium nickel hexacyanoferrate as a cathode material, J. Power Sources, 2017, 337, 204–211,  DOI:10.1016/j.jpowsour.2016.10.083.
183. W. Zhu, W. Wang, W. Xue, K. Kong, Z. Zhang, W. Ye, D. He and R. Zhao, Achieving a Zn-ion battery-capacitor hybrid energy storage device with a cycle life of more than 12,000 cycles, Composites, Part B, 2021, 207, 108555,  DOI:10.1016/j.compositesb.2020.108555.
184. G. Zhang, H. Yao, F. Zhang, Z. Gao, Q. Li, Y. Yang and X. Lu, A high over-potential binder-free electrode constructed of Prussian blue and MnO₂ for high performance aqueous supercapacitors, Nano Res., 2019, 12, 1061–1069,  DOI:10.1007/s12274-019-2347-2.
185. H. Yao, Q. Li, M. Zhang, Z. Tao and Y. Yang, Prolonging the cycle life of zinc-ion battery by introduction of [Fe(CN)₆]⁴⁻ to PANI via a simple and scalable synthetic method, Chem. Eng. J., 2020, 392, 123653,  DOI:10.1016/j.cej.2019.123653.
186. W. Deng, Z. Li, Y. Ye, Z. Zhou, Y. Li, M. Zhang, X. Yuan, J. Hu, W. Zhao, Z. Huang, C. Li, H. Chen, J. Zheng and R. Li, Zn²⁺ Induced Phase Transformation of K₂MnFe(CN)₆ Boosts Highly Stable Zinc-Ion Storage, Adv. Energy Mater., 2021, 11, 2003639,  DOI:10.1002/aenm.202003639.
187. L. Ye, H. Fu, R. Cao and J. Yang, Optimizing Mn in Prussian blue analogs with double redox active sites to induce boosted Zn²⁺ storage, J. Colloid Interface Sci., 2024, 664, 423–432,  DOI:10.1016/j.jcis.2024.03.047.
188. T. Cao, F. Zhang, M. Chen, T. Shao, Z. Li, Q. Xu, D. Cheng, H. Liu and Y. Xia, Cubic Manganese Potassium Hexacyanoferrate Regulated by Controlling of the Water and Defects as a High-Capacity and Stable Cathode Material for Rechargeable Aqueous Zinc-Ion Batteries, ACS Appl. Mater. Interfaces, 2021, 13, 26924–26935,  DOI:10.1021/acsami.1c04129.
189. Z. Jia, B. Wang and Y. Wang, Copper hexacyanoferrate with a well-defined open framework as a positive electrode for aqueous zinc ion batteries, Mater. Chem. Phys., 2015, 149–150, 601–606,  DOI:10.1016/j.matchemphys.2014.11.014.
190. Y. Zeng, X. F. Lu, S. L. Zhang, D. Luan, S. Li and X. W. (David) Lou, Construction of Co–Mn Prussian Blue Analog Hollow Spheres for Efficient Aqueous Zn-ion Batteries, Angew. Chem., 2021, 133, 22363–22368,  DOI:10.1002/ange.202107697.
191. S. Meng, Q. Zhang, Y. Liu, S. Liu, X. Yang and K. Feng, Low-defect potassium vanadyl hexacyanoferrate cathode material with high specific capacity for aqueous zinc ion batteries, J. Energy Storage, 2025, 105, 114754,  DOI:10.1016/j.est.2024.114754.
192. Y. Kong, Y. Xiao, S. Zhang, L. Chen, Z. Liu and Y. Wang, Open-framework aluminum hexacyanoferrate as a cathode material for high voltage aqueous zinc-ion batteries: effect of Al³⁺ cations on three-phase transition of AlFe(CN)₆, Inorg. Chem. Front., 2023, 10, 7274–7284,  10.1039/D3QI01725G.
193. C. Mao, Y. Chang, X. Zhao, X. Dong, Y. Geng, N. Zhang, L. Dai, X. Wu, L. Wang and Z. He, Functional carbon materials for high-performance Zn metal anodes, J. Energy Chem., 2022, 75, 135–153,  DOI:10.1016/j.jechem.2022.07.034.
194. T. Wei, Y. Liu, G. Yang and C. Wang, Aluminum vanadate hollow spheres as zero-strain cathode material for highly reversible and durable aqueous zinc-ion batteries, Energy Storage Mater., 2020, 30, 130–137,  DOI:10.1016/j.ensm.2020.04.039.
195. D. Luo, J. Wu, X. Chi and Y. Liu, Water Confinement by a Zn²⁺-Conductive Aqueous/Inorganic Hybrid Electrolyte for High-Voltage Zinc-Ion Batteries, ACS Appl. Energy Mater., 2023, 6, 3705–3713,  DOI:10.1021/acsaem.2c03617.
196. Y. Tan, H. Yang, C. Miao, Y. Zhang, D. Chen, G. Li and W. Han, Hydroxylation strategy unlocking multi-redox reaction of manganese hexacyanoferrate for aqueous zinc-ion battery, Chem. Eng. J., 2023, 457, 141323,  DOI:10.1016/j.cej.2023.141323.
197. J. Beitia, I. Ahedo, J. I. Paredes, E. Goikolea and I. Ruiz de Larramendi, Exploring Zinc-Doped Manganese Hexacyanoferrate as Cathode for Aqueous Zinc-Ion Batteries, Nanomaterials, 2024, 14, 1092,  DOI:10.3390/nano14131092.
198. W. A. Syed, A. K. Kakarla, H. Bandi, R. Shanthappa and J. S. Yu, Copper substituted manganese Prussian blue analogue composite nanostructures for efficient aqueous zinc-ion batteries, J. Energy Storage, 2024, 99, 113325,  DOI:10.1016/j.est.2024.113325.
199. J. Cao, Y. Xue, Z. Ji, J. Pu, X. Shen, L. Kong and A. Yuan, CoNi hexacyanoferrate nanoparticles anchored on carbon nanotubes as superior cathode materials for rechargeable aqueous zinc-ion batteries, J. Energy Storage, 2024, 86, 111413,  DOI:10.1016/j.est.2024.111413.
200. Z. Liu, G. Pulletikurthi and F. Endres, A Prussian Blue/Zinc Secondary Battery with a Bio-Ionic Liquid–Water Mixture as Electrolyte, ACS Appl. Mater. Interfaces, 2016, 8, 12158–12164,  DOI:10.1021/acsami.6b01592.
201. L. Xu, X. Ye, X. Xiao, P. Wu, S.-L. Zhang, Y. Meng and S. Liu, One-Step Coprecipitation Synthesis of Titanium Hexacyanoferrate Nanosheet-Assembled Hierarchical Nanoflowers for Aqueous Zinc-Ion Batteries, ACS Appl. Nano Mater., 2023, 6, 19997–20005,  DOI:10.1021/acsanm.3c03801.
202. Y. Xue, H. Zhou, X. Suo, J. Tao, C. Zhang, Z. Ji, X. Shen, L. Kong and A. Yuan, Polyaniline-modified amorphous tin-based Prussian blue analogue as cathodes for long-life aqueous zinc ion batteries, J. Energy Storage, 2024, 98, 113140,  DOI:10.1016/j.est.2024.113140.
203. M. Chen, Y. Cui, W. Liu, Z. Shi, H. Dong, H. Yue, Z. Cao, Z. Lu, S. Yang and Y. Yin, Ti₄O₇ coating creates a highly stable Zn anode for aqueous zinc-ion batteries, Inorg. Chem. Front., 2024, 11, 4748–4756,  10.1039/D4QI00808A.
204. B. Lee, M. G. Son, S. A. Song, K. Kim, J. Y. Woo, Y. Choa, J. Kang and S. N. Lim, Insights into the design of zincophilic artificial protective layers enabling uniform nucleation and deposition for stable dendrite-free Zn anodes, J. Colloid Interface Sci., 2025, 680, 640–650,  DOI:10.1016/j.jcis.2024.11.097.
205. C. Zhang, C. Li, D. Chen, Z. He, Y. Cheng, T. You, J. Zhou, H. Yu, Z. Xie, C. Kang and Y. Chen, Zn²⁺ flux regulator to modulate the interface chemistry toward highly reversible Zn anode, J. Colloid Interface Sci., 2025, 682, 232–241,  DOI:10.1016/j.jcis.2024.11.215.
206. G. Zhu, H. Zhang, J. Lu, Y. Hou, P. Liu, S. Dong, H. Pang and Y. Zhang, 3D Printing of MXene–Enhanced Ferroelectric Polymer for Ultrastable Zinc Anodes, Adv. Funct. Mater., 2024, 34, 2305550,  DOI:10.1002/adfm.202305550.
207. L.-L. Zhao, S. Zhao, N. Zhang, P.-F. Wang, Z.-L. Liu, Y. Xie, J. Shu and T.-F. Yi, Construction of stable Zn metal anode by inorganic functional protective layer toward long-life aqueous Zn-ion battery, Energy Storage Mater., 2024, 71, 103628,  DOI:10.1016/j.ensm.2024.103628.
208. M. Bai, J. Chen, Q. Li, X. Wang, J. Li, X. Lin, S. Shao, D. Li and Z. Wang, A “Zn²⁺ in Salt” Interphase Enabling High–Performance Zn Metal Anodes, Small, 2024, 20, 2403380,  DOI:10.1002/smll.202403380.
209. J. Lu, T. Wang, J. Yang, X. Shen, H. Pang, B. Sun, G. Wang and C. Wang, Multifunctional Self–Assembled Bio–Interfacial Layers for High–Performance Zinc Metal Anodes, Angew. Chem., Int. Ed., 2024, 63, e202409838,  DOI:10.1002/anie.202409838.
210. J. He, W. Zhou, J. Li, S. Chen, D. Zhu and Y. Chen, Bifunctional interface of metal–organic framework synergized with bismuth endows high stable zinc anode, Chem. Eng. J., 2024, 485, 149740,  DOI:10.1016/j.cej.2024.149740.
211. F. Ji, S. Gou, J. Tang, Y. Xu, S. M. Eldin, W. Mai, J. Li and B.-T. Liu, High-performance Zn-ion hybrid supercapacitor enabled by a lightweight polyimide-based anode, Chem. Eng. J., 2023, 474, 145786,  DOI:10.1016/j.cej.2023.145786.
212. W. He, T. Gu, X. Xu, S. Zuo, J. Shen, J. Liu and M. Zhu, Uniform In Situ Grown ZIF-L Layer for Suppressing Hydrogen Evolution and Homogenizing Zn Deposition in Aqueous Zn-Ion Batteries, ACS Appl. Mater. Interfaces, 2022, 14, 40031–40042,  DOI:10.1021/acsami.2c11313.
213. Y. Wang, Y. Liu, H. Wang, S. Dou, W. Gan, L. Ci, Y. Huang and Q. Yuan, MOF-based ionic sieve interphase for regulated Zn²⁺ flux toward dendrite-free aqueous zinc-ion batteries, J. Mater. Chem. A, 2022, 10, 4366–4375,  10.1039/D1TA10245A.
214. Q. Gou, Z. Chen, H. Luo, J. Deng, B. Zhang, N. Xu, J. Cui, Y. Zheng, M. Li and J. Li, Synergistic Modulation of Mass Transfer and Parasitic Reactions of Zn Metal Anode via Bioinspired Artificial Protection Layer, Small, 2024, 20, 2305902,  DOI:10.1002/smll.202305902.
215. Y. Xiang, L. Zhou, P. Tan, S. Dai, Y. Wang, S. Bao, Y. Lu, Y. Jiang, M. Xu and X. Zhang, Continuous Amorphous Metal–Organic Frameworks Layer Boosts the Performance of Metal Anodes, ACS Nano, 2023, 17, 19275–19287,  DOI:10.1021/acsnano.3c06367.
216. Y. Lee, Y. Jeoun, J. H. Kim, J. Shim, K. Ahn, S. Yu and Y. Sung, Selective Ion Transport Layer for Stable Aqueous Zinc–Ion Batteries, Adv. Funct. Mater., 2024, 34, 2310884,  DOI:10.1002/adfm.202310884.
217. X. Xu, Y. Xu, J. Zhang, Y. Zhong, Z. Li, H. Qiu, H. Bin Wu, J. Wang, X. Wang, C. Gu and J. Tu, Quasi-Solid Electrolyte Interphase Boosting Charge and Mass Transfer for Dendrite-Free Zinc Battery, Nano-Micro Lett., 2023, 15, 56,  DOI:10.1007/s40820-023-01031-7.
218. C. Peng, S. Mei, X. Chen, Z. Wei, F. Huang, Y. Zhang, L. Ding, Y. Peng and Z. Deng, π-d Interaction to promote Zn ion de-solvation and transference toward high-performance Zn-MnO₂ battery, J. Alloys Compd., 2024, 1002, 175486,  DOI:10.1016/j.jallcom.2024.175486.
219. X. Liu, Z. Han, S. Zhao, H. Tang, T. Tian, Q. Weng, X. Liu and T. Liu, A HKUST-1 coating with copper metal active site enables stabilized zinc metal anode, Mater. Today Energy, 2024, 44, 101659,  DOI:10.1016/j.mtener.2024.101659.
220. H. Zhang, M. Zhao and Y. S. Lin, Stability of ZIF-8 in water under ambient conditions, Microporous Mesoporous Mater., 2019, 279, 201–210,  DOI:10.1016/j.micromeso.2018.12.035.
221. X. Luo, Q. Nian, Z. Wang, B.-Q. Xiong, S. Chen, Y. Li and X. Ren, Building a seamless water-sieving MOF-based interphase for highly reversible Zn metal anodes, Chem. Eng. J., 2023, 455, 140510,  DOI:10.1016/j.cej.2022.140510.
222. Y. Xiang, Y. Zhong, P. Tan, L. Zhou, G. Yin, H. Pan, X. Li, Y. Jiang, M. Xu and X. Zhang, Thickness–Controlled Synthesis of Compact and Uniform MOF Protective Layer for Zinc Anode to Achieve 85% Zinc Utilization, Small, 2023, 19, 2302161,  DOI:10.1002/smll.202302161.
223. L. Lei, B. Zhao, X. Pei, L. Gao, Y. Wu, X. Xu, P. Wang, S. Wu and S. Yuan, Optimizing Porous Metal–Organic Layers for Stable Zinc Anodes, ACS Appl. Mater. Interfaces, 2024, 16, 485–495,  DOI:10.1021/acsami.3c12369.
224. X. Chen, T. Liu, Y. Ding, X. Sun, J. Huang, J. Qiao and S. Peng, Controlled nucleation and growth for the dendrite-free zinc anode in aqueous zinc-ion battery, J. Alloys Compd., 2024, 970, 172584,  DOI:10.1016/j.jallcom.2023.172584.
225. C. Li, L. Liang, X. Liu, N. Cao, Q. Shao, P. Zou and X. Zang, A lean–zinc anode battery based on metal–organic framework–derived carbon, Carbon Energy, 2023, 5, e301,  DOI:10.1002/cey2.301.
226. Y. Wei, M. Zheng, W. Zhu and H. Pang, Hollow structures Prussian blue, its analogs, and their derivatives: Synthesis and electrochemical energy–related applications, Carbon Neutralization, 2023, 2, 271–299,  DOI:10.1002/cnl2.64.
227. H. Gupta, Y. Dahiya, H. K. Rathore, K. Awasthi, M. Kumar and D. Sarkar, Energy-Dense Zinc Ion Hybrid Supercapacitors with S, N Dual-Doped Porous Carbon Nanocube Based Cathodes, ACS Appl. Mater. Interfaces, 2023, 15, 42685–42696,  DOI:10.1021/acsami.3c09202.
228. C. Wang, Q. Xie, T. Guo, M. Fang, W. Mao, Y. Zhang, H. Wang, X. Ma, Y. Wu, S. Li and J. Han, Understanding the Role of Titanium Metal–Organic Framework Nanosheets in Modulating Anode Chemistry for Aqueous Zinc-Ion Batteries, Nano Lett., 2023, 23, 10930–10938,  DOI:10.1021/acs.nanolett.3c03161.
229. K. Sun, Y. Shen, J. Min, J. Pang, Y. Zheng, T. Gu, G. Wang and L. Chen, MOF-derived Zn/Co co-doped MnO/C microspheres as cathode and Ti₃C₂@Zn as anode for aqueous zinc-ion full battery, Chem. Eng. J., 2023, 454, 140394,  DOI:10.1016/j.cej.2022.140394.
230. D. Lee, H. Kim, W. Kim, S. Cho, K. Baek, K. Jeong, D. B. Ahn, S. Park, S. J. Kang and S. Lee, Water–Repellent Ionic Liquid Skinny Gels Customized for Aqueous Zn–Ion Battery Anodes, Adv. Funct. Mater., 2021, 31, 2103850,  DOI:10.1002/adfm.202103850.
231. R. Meng, H. Li, Z. Lu, C. Zhang, Z. Wang, Y. Liu, W. Wang, G. Ling, F. Kang and Q. Yang, Tuning Zn–Ion Solvation Chemistry with Chelating Ligands toward Stable Aqueous Zn Anodes, Adv. Mater., 2022, 34, 2200677,  DOI:10.1002/adma.202200677.
232. Y. Cui, Q. Zhao, X. Wu, Z. Wang, R. Qin, Y. Wang, M. Liu, Y. Song, G. Qian, Z. Song, L. Yang and F. Pan, Quasi-solid single Zn-ion conductor with high conductivity enabling dendrite-free Zn metal anode, Energy Storage Mater., 2020, 27, 1–8,  DOI:10.1016/j.ensm.2020.01.003.

---