3D wood-derived vertical multichannel carbon framework with functional fillers for high-performance Zn-ion hybrid supercapacitors

Abstract

Severe dendrite and side reaction issues of metallic zinc anodes are vital factors that result in the poor cycling ability of aqueous zinc-ion hybrid supercapacitors (ZHSCs). Herein, we developed a three-dimensional wood-derived vertical multichannel framework modified by functional fillers. The modified 3D carbon-based framework possesses optimized zincophilicity and a hierarchical porous structure, which can effectively accommodate volume expansion and homogenize local current density for uniform Zn deposition. Thus, the designed 3D carbon-based framework delivers a superior coulombic efficiency of 98.6% over 1300 cycles at 10 mA cm⁻², while the symmetric cell with the carbon-based Zn anode exhibits 1100 h cycles at 1 mA cm⁻² (1 mAh cm⁻²). Moreover, benefiting from its high porosity, the 3D carbon-based framework can be used as a binder-free cathode material for constructing high-performance ZHSCs. The as-designed full cell exhibited a remarkable areal capacitance of 3172.8 mF cm⁻² and extremely long-term cycle stability of 15 000 cycles at 40 mA cm⁻². This strategy of zincophilicity regulation by introducing functional fillers into a 3D carbon-based framework may provide a new idea for fabricating ZHSCs with high stability and capacity.

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Panpan Zhang

Dr Panpan Zhang is a full professor at the School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), China. He received his B.S. and M.S. degrees from Beijing University of Chemical Technology (BUCT). Subsequently, he obtained his PhD degree in 2019 under the supervision of Prof. Xinliang Feng at Technische Universität Dresden (TUD). Afterwards, he held a post-doctoral position in Prof. Feng's group from 2019 to 2021. His research interests focus on 2D crystalline materials and their energy storage applications. He has published more than 80 papers with more than 10000 citations and an H-index of 54.

1. Introduction

Metallic zinc (Zn) anodes for Zn-ion hybrid supercapacitors (ZHSCs) demonstrate exceptional promise due to their high theoretical capacity (820 mAh g⁻¹, 5855 mAh cm⁻³), low redox potential (−0.76 V vs. SHE), and environmental compatibility.^1–3 These advantages endow ZHSCs with broad prospects for practical applications in next-generation energy storage technologies. However, adverse side reactions, such as Zn dendrite growth, corrosion passivation, and hydrogen evolution reaction (HER), severely degrade the long-term reversibility of ZHSCs, thereby inhibiting their commercial applications.^4,5 Specifically, Zn dendrite growth can pierce the separator and cause a short circuit, which is driven by uneven current distribution and uneven Zn deposition.^6,7

Current mitigation strategies focus on interfacial engineering,^8–10 electrolyte modulation,^11–13 and electrode host design.^14–16 These strategies collectively target to suppress Zn corrosion, mitigate passivation, reduce volume change, and inhibit Zn dendrite growth. In these strategies, employing 3D conductive substrates as current collectors for electrode structure design is recognized as a promising solution to prevent Zn dendrite formation. Carbon-based conductive substrates (e.g., carbon fibers,¹⁷ graphene foams,¹⁶ and carbon nanotubes¹⁸) exhibit superior chemical stability for homogeneous Zn deposition compared with metallic frameworks.¹⁹ Notably, wood-derived carbon can buffer mechanical deformation caused by volume changes during long-term Zn plating/stripping cycles through its robust interconnected 3D framework. Furthermore, its ordered vertical channels can facilitate the transport of electrolytes, which can effectively enhance the electrochemical performance of the electrode.^20–22 Thus, wood is a reasonable choice as the biomass precursor to produce a 3D framework with low tortuosity and interconnected channels. However, the poor porosity utilization rate and zincophobicity of sp²-hybridized carbon can adversely affect the uniform deposition of Zn.^23–25 Thus, regulating the zincophilicity of the 3D carbon framework based on pore structure design and oxygen functional groups could be a promising strategy for the development of Zn anodes.

In this work, we report a 3D wood-derived vertical multichannel carbon framework (3D-VMCF) with glucose-derived carbon spheres (3D-VMCF-CS) as surface-modified functional regulators. The synergistic effect of the hierarchical porous structure and zincophilicity regulation enables the 3D-VMCF-CS@Zn anode with superior cycling life (1 mA cm⁻²/1 mAh cm⁻², 1100 h) in symmetric cells. Moreover, the 3D-VMCF-CS can achieve more than 1300 reversible plating/stripping cycles in half-cells with a coulombic efficiency (CE) of approximately 98.6% under a high current density of 10 mA cm⁻². Remarkably, when paired with a 3D-VMCF-CS cathode, the assembled ZHSCs exhibit excellent cycling stability over 15 000 cycles at 40 mA cm⁻². The hierarchical porous structure design based on 3D vertical multichannel carbon-based frameworks with functional fillers provides a reference direction for the customization of Zn anodes.

2. Experimental

2.1 Materials

Pine wood was purchased from Ji'an Handicrafts Co., Ltd. Glucose was purchased from Sinopharm Chemical Reagent Co., Ltd and used without further purification.

2.2 Synthesis of the 3D-VMCF and 3D-VMCF-CS

The original wood was cut into chips with a dimension of 2.0 × 2.0 × 0.1 cm³ as a standard sample. Subsequently, the wood chips were immersed in glucose solution with different concentrations (0, 0.25, 0.5, and 0.75 M), followed by hydrothermal treatment at 160 °C for 6 h. After natural drying, the pre-treated wood chips were stabilized at 260 °C (2 °C min⁻¹) for 3 h and carbonized at 900 °C (5 °C min⁻¹) for another 3 h in a tubular furnace under an argon atmosphere.²⁶ The stepwise calcination method can preserve the integrity of the wood structure, thus maintaining the vertical channels. The obtained samples are denoted as 3D-VMCF-CS0, 3D-VMCF-CS1, 3D-VMCF-CS2, and 3D-VMCF-CS3. The electrode working areas were fixed at 0.5 × 0.5 cm², while the mass loading was measured at about 20.7 ± 1.5 mg cm⁻². Besides, the 3D-VMCF was prepared through the same carbonization steps without hydrothermal treatment for a comparative study with a loading amount of approximately 15.2 ± 1.5 mg cm⁻².

2.3 Synthesis of 3D-VMCF-CS-based Zn anodes

The 3D-VMCF@Zn and 3D-VMCF-CS2@Zn anodes were prepared via electrochemical deposition. In a standard three-electrode system, the 3D carbon-based framework, Ag/AgCl, and Pt wire were used as the working electrode, reference electrode, and counter electrode, respectively. During the deposition process, the current density was selected to be 1–5 mA cm⁻², and the capacity was 10 mAh cm⁻² in an aqueous electroplating solution containing 0.5 M ZnSO₄ and 0.5 M NaSO₄.

2.4 Electrochemical measurements

To assess the electrochemical behavior and coulombic efficiency (CE) of Zn plating and stripping, CR2032-type coin cells were assembled with Cu foil, 3D-VMCF, or 3D-VMCF-CS2 as working electrodes. Zn metal served as the counter/reference electrode, while a glass fiber separator was used in a 3 M Zn(CF₃SO₃)₂ electrolyte. Electrochemical performance was evaluated using a LAND battery test system at 25 °C. For CE evaluation; Zn was plated onto various substrates with a capacity of 0.5 mAh cm⁻² and subsequently charged to 0.5 V to strip the Zn in each cycle at 1 mA cm⁻².

To assess cycling stability, symmetric cells were assembled with Zn foil, 3D-VMCF@Zn, and 3D-VMCF-CS2@Zn electrodes. These cells were cycled at 1 mA cm⁻² with a capacity of 1 mAh cm⁻². Linear scan voltammetry (LSV) was conducted using a CHI660E electrochemical workstation (Shanghai CH Instruments Co., China). The hydrogen evolution polarization curves were collected using LSV in a 1 M Na₂SO₄ electrolyte at a scan rate of 5 mV s⁻¹ in a three-electrode system with zinc foil, 3D-VMCF@Zn, or 3D-VMCF-CS2@Zn as the working electrode; Pt wire as the counter electrode; and Ag/AgCl as the reference electrode.

For full cells, the 3D-VMCF-CS2 cathode was directly used without any conductive additives or binders. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) tests were performed using a voltage window from 0 to 1.8 V for 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSCs. The 3D-VMCF-CS2@Zn anode was obtained via electrochemical deposition with a fixed capacity of 10 mAh cm⁻². Besides, a Swagelok cell was assembled to investigate electrochemical impedance spectra (EIS) using the CHI660E electrochemical workstation with a frequency range of 100 kHz to 100 mHz. The cycling capabilities were measured at 40 mA cm⁻², and the rate performance was tested in the range of 1–10 mA cm⁻². The areal capacitance (C, mF cm⁻²) was calculated using the following equation:^26,27

C = It/Sv (1)

where I/S(mA cm⁻²), t(s), and v(V) are the current density, discharge time, and voltage window, respectively.

The areal energy density (E, mWh cm⁻²) and power density (P, mW cm⁻²) were calculated using the following equations:

E = C(ΔV)²/(2 × 3.6) (2)

P = 3600E/Δt (3)

where C (mF cm⁻²), ΔV(V), and Δt(s) are the areal capacitance, discharge voltage range, and discharge time, respectively.

2.5 Material characterization

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images were recorded on a field emission scanning electron microscope (TESCAN CLARA) and a transmission electron microscope (JEM2100), respectively. X-ray diffraction (XRD) patterns were obtained with an X-ray diffractometer (XRD-7000) using Cu-Kα radiation (λ = 0.154 nm) at 40 kV and 30 mA at room temperature. Binding energies were characterized using X-ray photoelectron spectroscopy (XPS, Thermo Scientific K-Alpha). N₂ adsorption/desorption isotherms were tested through ASAP 2460 for investigating the specific surface area and pore distribution. Fourier transform infrared spectroscopy (FT-IR) was performed for determining the oxygen functional groups (Nicolet, iS50). Raman spectra were recorded using a LabRAM HR800 Raman spectroscope. Contact angles were tested on a contact angle goniometer (SDC-100 China) using deionized water at room temperature.

3. Results and discussion

3.1 Synthesis and characterization of the 3D-VMCF-CS

As illustrated in Fig. 1a, the 3D-VMCF-CS was successfully developed through a two-step approach. During the first hydrothermal treatment, the introduction of glucose as an extrinsic carbon source generated oxygen-rich amorphous carbon on the surface of biomass wood. Subsequently, the 3D-VMCF-CS was obtained through stabilization and carbonization. Without the first step, the prepared 3D-VMCF showed an intrinsic vertical porous and continuous structure (Fig. 1b and c).²⁶ Following the addition of glucose, spherical particles were observed on the surface of the 3D-VMCF-CS. Besides, the mass retention rate for the 3D-VMCF-CS2 (21.3%) showed an obvious increase compared with that of the 3D-VMCF (14.8%), which can be attributed to the successful incorporation of carbon spheres (Fig. S1). Fig. S2 shows the SEM image of 3D-VMCF-CS1 with sparse carbon spheres, suggesting that glucose is difficult to form a dense layer at such a low concentration (0.25 M). As the concentration of glucose was further increased to adjust the density of the functional fillers, 3D-VMCF-CS2 (0.5 M) displayed a uniform distribution of carbon spheres in the size range of 400–1000 nm on the surface (Fig. 1d and e). However, when the glucose concentration was further increased to 0.75 M, 3D-VMCF-CS3 did not exhibit a denser modification layer as expected (Fig. S3). This result may be related to the increased viscosity of the solution, which restricts the growth of carbon spheres and causes severe agglomeration. TEM measurements were performed to explore the influence of the introduction of carbon spheres on the microstructure of the 3D-VMCF-CS. As displayed in Fig. 1g, 3D-VMCF-CS2 exhibits a distinct porous structure with a pore size of approximately 25–50 nm compared with the 3D-VMCF (Fig. 1f), which may be related to the etching effect of the oxygen-rich amorphous carbon during the carbonization process. Besides, both 3D-VMCF and 3D-VMCF-CS2 display similar short-range ordered lattice fringes in their high-resolution TEM images (Fig. 1h and i), which could be attributed to the (002) plane of graphite microcrystals formed during the carbonization process.^23,24,28

Fig. 1 (a) Schematic of the fabrication of the 3D-VMCF and 3D-VMCF-CS2. Top- and side-view SEM images of (b and c) the 3D-VMCF and (d and e) 3D-VMCF-CS2. TEM images of (f) the 3D-VMCF and (g) 3D-VMCF-CS2. High-resolution TEM images of (h) the 3D-VMCF and (i) 3D-VMCF-CS2.

Fig. 2a presents the XRD patterns of 3D-VMCF-CS with different glucose concentrations and 3D-VMCF. The typical (002) and (101) peaks correspond to the degree of graphitization, which suggests that the introduction of glucose did not bring unexpected impurities. Moreover, 3D-VMCF-CS2 (24.2°) showed the smallest water contact angle compared with 3D-VMCF-CS0 (51.1°), 3D-VMCF-CS1 (37.9°), 3D-VMCF-CS3 (29.5°), and 3D-VMCF (59.6°), demonstrating much improved zincophilicity (Fig. 2b). XPS analysis was conducted to further investigate the effect of carbon spheres on the elemental composition of the 3D-VMCF (Fig. S4 and S5). Notably, the oxygen atomic percentage of the 3D-VMCF-CS significantly increased following the introduction of glucose and that of 3D-VMCF-CS2 reached the maximum value of 5.9 at% (Fig. 2c). Fig. 2d illustrates the high-resolution C 1s spectra of the 3D-VMCF, 3D-VMCF-CS0, and 3D-VMCF-CS2, which can be deconvoluted into four peaks assigned to C=C, C–C, C–O, and C=O/O–C=O.^29,30 The C–O and C=O/O–C=O peaks for 3D-VMCF-CS2 show apparent intensity enhancement. Correspondingly, the O 1s spectra of 3D-VMCF-CS2 (Fig. 2e) display a pronounced O–C=O peak, accompanied by a right shift in binding energies, which can be attributed to the strong interaction between the oxygen functional groups and the carbon framework.

Fig. 2 (a) XRD patterns of the 3D-VMCF and 3D-VMCF-CS with different glucose additions. (b) Water contact angles of different substrates. (c) Contents of the O atom calculated from XPS results. (d and e) High-resolution C 1s and O 1s XPS spectra. (f) FT-IR spectra, (g) Raman spectra, (h) N₂ adsorption–desorption isotherms (inset: pore volume of mesopores/micropores), and (i) corresponding pore size distributions of the 3D-VMCF, 3D-VMCF-CS0, and 3D-VMCF-CS2.

FT-IR spectra were employed to further demonstrate the functional groups incorporated in the carbon framework. As displayed in Fig. 2f, the peaks appearing at 3439 cm⁻¹ are related to the stretching vibration peaks of the O–H band, while the adsorption peaks at 1629 and 1096 cm⁻¹ are caused by the C=C and C–O–C bonds, respectively.³¹ Besides, a new peak at 1395 cm⁻¹ for 3D-VMCF-CS2 indicates the formation of the –COOH bond, which can also be demonstrated by the significant enhancement of O–C=O signals in the XPS results. Moreover, the right shift of the D-band in the Raman spectra (Fig. 2g) of 3D-VMCF-CS2 corresponds to localized defects, which are caused by the partial decomposition of oxygen functional groups during carbonization.³² Besides, Fig. 2h shows the N₂ adsorption–desorption isotherms (inset: micro-/mesopore distribution). The pronounced hysteresis loop for 3D-VMCF-CS2 within the 0.4–0.9 P/P₀ range confirms the generation of mesopores.^33,34 Among the samples, 3D-VMCF-CS2 exhibits the highest specific surface area (780 m² g⁻¹) compared to the 3D-VMCF (632 m² g⁻¹) and 3D-VMCF-CS0 (680 m² g⁻¹). Pore size distribution curves (Fig. 2i) present the average pore diameters of 2.3, 3.4, and 3.8 nm for the 3D-VMCF, 3D-VMCF-CS0, and 3D-VMCF-CS2, respectively. Altogether, these results indicate that the functional filler-modified 3D-VMCF-CS possesses improved zincophilicity and superior hierarchical porosity, making it a preeminent host for the Zn anode.^35,36 Consequently, 3D-VMCF@Zn and 3D-VMCF-CS2@Zn were synthesized under the same electrodeposition conditions (5 mA cm⁻², 10 mAh cm⁻²) as those for the composite Zn anodes. The Zn 2p XPS spectrum for 3D-VMCF-CS2@Zn shows that Zn species exist mainly in the metallic state (Fig. S6). Besides, the peak originating from C=O shows significant enhancement in the high-resolution C 1s XPS spectrum, which is attributed to the adsorption of Zn²⁺ on the 3D-VMCF-CS2 surface. Meanwhile, the peak intensity corresponding to the C=O bond in the high-resolution O 1s XPS spectrum also increased significantly. This result indicates that Zn²⁺ is first captured by the oxygen-containing functional groups on 3D-VMCF-CS2 to form zinc carboxylate. Subsequently, chemical adsorption further promotes the homogeneous nucleation of Zn and generates a dense Zn deposition layer, as shown in the SEM images. In 3D-VMCF@Zn (Fig. S7a), Zn was deposited as vertical petal-like clusters. In contrast, Fig. S7b displays the horizontally aligned Zn flakes on 3D-VMCF-CS2@Zn. Moreover, aside from the distinct peaks of Zn (JCPDS#4-381), the XRD pattern of 3D-VMCF@Zn in Fig. S8 also exhibits additional characteristic peaks corresponding to ZnO (JCPDS#36-145).³¹ This result indicates that the sharp petal-like Zn in 3D-VMCF@Zn is more prone to oxidation. Thus, the smooth Zn deposition layer is conducive to suppressing side reactions and realizing long-term cycling stability.³⁷

3.2 Electrochemical performance of 3D-VMCF-CS2-based Zn anodes

The electrochemical performance of Zn‖Cu, Zn‖3D-VMCF@Zn, and Zn‖3D-VMCF-CS2@Zn was evaluated to investigate the modification effect of carbon spheres in the Zn plating/stripping process (10 mA cm⁻², 0.5 mAh cm⁻²). As shown in Fig. 3a, the Zn‖3D-VMCF-CS2@Zn cell showed a highly reversible electrochemical process with a CE of 98.6% after 1300 cycles, while the Zn‖3D-VMCF@Zn cell failed after 226 cycles with a CE of 83.8%. Unlike 3D-VMCF-CS2 and the 3D-VMCF, bare Cu can hardly withstand the rapid growth of Zn at high current density. The CE of the bare Zn‖Cu cell fluctuated dramatically during the first cycle and was completely short-circuited during the 146th cycle. The introduction of carbon spheres on the 3D carbon-based framework effectively enhances the reversibility of Zn plating/stripping by homogenizing interfacial charge distribution and accommodating volume change. The impressively high CE values and prolonged lifespan are superior to those reported for 3D Zn anodes (Fig. 3b and Table S1). Subsequently, the rate performance of the symmetric cells with bare Zn, 3D-VMCF@Zn, and 3D-VMCF-CS2@Zn electrodes was measured at current densities ranging from 0.5 to 10 mA cm⁻² at an areal capacity of 1 mAh cm⁻² (Fig. 3c). The polarization voltage of 3D-VMCF-CS2@Zn was significantly reduced compared with bare Zn at different current densities, indicating superior fast zinc-ion transport capability and electrochemical stability.

Fig. 3 (a) Coulombic efficiencies of the half-cells at a current density of 10 mA cm⁻² with the cut-off voltage of 0.5 V. (b) Comparison of the current densities for Zn deposition and cycle capability with previously reported literature. (c) Rate performance of symmetric cells from 0.5 to 10 mA cm⁻² and back to 1 mA cm⁻² for 1 mAh cm⁻². (d) Long-term cycling performance of symmetric cells with bare Zn, 3D-VMCF@Zn, and 3D-VMCF-CS2@Zn electrodes at 1 mA cm⁻² for 1 mAh cm⁻². (e) LSV curves using a three-electrode system. (f) XRD patterns of 3D-VMCF-CS2 before and after the long-term cycle test.

Next, to explore the modification effect of carbon spheres in inhibiting zinc dendrite growth, symmetric cells were assembled with 3D-VMCF-CS2@Zn, 3D-VMCF@Zn, and bare Zn electrodes. As illustrated in Fig. 3d, the polarization voltage of the cell with bare Zn electrodes suddenly dropped at about 100 h, which could be attributed to the persistent zinc dendrite growth, passivation, and short-circuiting of the cell. It is evident that 3D composite Zn electrodes show significantly prolonged lifetime (1100 h for 3D-VMCF-CS2@Zn and 400 h for 3D-VMCF@Zn) compared to bare Zn electrodes. The excellent cycling performance of 3D-VMCF-CS2@Zn verifies that the modification layer formed by carbon spheres effectively reduces the side reactions at the electrode/electrolyte interface by inducing uniform Zn deposition. As illustrated in Fig. 3e, the LSV curve of 3D-VMCF-CS2@Zn shows a higher HER overpotential compared with bare Zn and 3D-VMCF@Zn, demonstrating the suppressed side reactions.^31,38 Moreover, XRD measurement after cycling test was further employed to examine the structure stability of 3D-VMCF-CS2. The nearly unchanged XRD patterns of 3D-VMCF-CS2 before and after the cycle confirm its robust durability as a conductive framework. The slight shift in the (002) peak for 3D-VMCF-CS2 could be ascribed to the interlayer expansion caused by repeated intercalation/deintercalation of Zn²⁺ during the long-term cycling process. Besides, the structural integrity of 3D-VMCF-CS2 (Fig. S9) after repeated cycles was maintained, illustrating its mechanical robustness.

3.3 Electrochemical behavior of 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSCs

To demonstrate the feasibility of 3D-VMCF-CS2 in practical applications, a full cell was assembled using the 3D-VMCF-CS2@Zn anode and 3D-VMCF-CS2 cathode, as illustrated in Fig. 4a. To identify a suitable voltage range, CV curves at 0–2.2 V were plotted for 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSCs (Fig. S10). As shown in Fig. S10, the device exhibited a typical capacitance behavior in the range of 0–1.8 V without obvious polarization. Besides, both 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 and Zn‖3D-VMCF-CS2 ZHSCs exhibit comparable CV curves with a rectangular-like shape, indicating typical capacitive behavior (Fig. 4b and S11a). The nearly rectangular CV profiles of the ZHSCs at different scan rates indicate the excellent electrochemical stability of the 3D-VMCF-CS2@Zn anode. The GCD curves of the 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSC with different current densities (Fig. 4c) show a superior areal capacitance of 3172.8 mF cm⁻² at 1 mA cm⁻² compared with the Zn‖3D-VMCF-CS2 ZHSC (Fig. S11b). Based on the synergistic effect of improved zincophilicity and the hierarchical porous structure, the 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSC presents high-rate capability at different current densities (Fig. S12). When the current density was restored to 1.0 mA cm⁻², the 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSC maintained a specific capacitance retention of 98% (Fig. 4d). These results clearly demonstrate the feasibility and practicality of the oxygen-rich functional group-modified 3D-VMCF in aqueous ZHSCs. Subsequently, the self-discharge behavior of the ZHSCs was evaluated by performing three continuous cycles, with a 60 h resting period before discharging (Fig. 4e and f). The CE of the Zn‖3D-VMCF-CS2 ZHSC reached 103.8%, which could be attributed to the corrosion of Zn during the resting process, leading to the release of additional charges. In contrast, 3D-VMCF-CS2 can effectively inhibit side reactions by facilitating uniform Zn deposition. Thus, 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSC exhibits a significantly optimized CE of 99.3%.

Fig. 4 (a) Structural design of 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSCs. (b) CV curves at different scan rates, (c) areal capacitances under different current densities, and (d) rate performance from 1 to 10 mA cm⁻² of the assembled ZHSCs. Self-discharge curves of full cells with (e) the 3D-VMCF-CS2@Zn anode and (f) bare Zn anode. (g) Ragone plots in comparison to other reported ZHSCs. (h) GCD curves for two and three ZHSCs connected in series and parallel. (i) Cycling stability of the ZHSCs with the 3D-VMCF-CS2@Zn anode and bare Zn anode at 40 mA cm⁻².

The Ragone plots displayed in Fig. 4g further demonstrate the overall performance of the ZHSCs based on areal energy and power densities. Notably, the 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSCs deliver a maximum areal energy density of 1260.7 μWh cm⁻² at 0.9 mW cm⁻², outperforming most recently reported ZHSCs (Table S2).^39–47 To satisfy the practical application standards, individual units were connected in series and parallel for higher voltage and capacitance. As illustrated in Fig. 4h, the three ZHSCs connected in series can reach a high voltage of 5.4 V. Two ZHSCs connected in series can light up a 2.0 V LED lamp (insert image). The lighting process is demonstrated in Video S1 with a duration of 20 min (Fig. S13). The brightness of the LED started to decline after 3 min and then continued to decrease and maintained a weak light after 20 min. Besides, the 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSC displays remarkable cycling stability (15 000 cycles) and superior capacitance retention (78.5%) under a high current density of 40 mA cm⁻² (Fig. 4i). The superior electrochemical performance of the 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSC can be attributed to its well-designed anode, offering excellent porosity and zincophilicity for fast charge transport. As shown in Fig. S14, compared with the charge transfer resistance (R_ct) of the bare Zn anode, that of the assembled ZHSCs is 52.4 Ω, which is larger than that of the 3D-VMCF-CS2@Zn electrode (2.8 Ω). The 3D-VMCF-CS2 framework enables a cathode with a highly conductive network, and the rich porous channel further promotes rapid Zn²⁺ transport. Therefore, the designed 3D carbon-based framework can significantly improve the cycling stability of the ZHSCs.

4. Conclusions

In summary, we constructed 3D carbon-based frameworks with vertical multichannel host design for high-performance ZHSCs. The hierarchical porous structure with oxygen-rich functional groups can effectively homogenize interfacial charge distribution and suppress side reactions. As a result, the prepared 3D-VMCF-CS2@Zn anode achieved superior Zn stripping/plating performance with a prolonged lifespan. More importantly, the 3D-VMCF-CS2@Zn‖3D-VMCF-CS2 ZHSCs exhibited excellent areal capacitance (3172.8 mF cm⁻²) with long-term cycling stability (15 000 cycles). These results verified the practicality of carbon spheres as functional fillers for modulating the zincophilicity and pore composition of 3D carbon-based frameworks. This work highlights the importance of zincophilicity and pore structure design in Zn anodes for developing high-performance aqueous energy storage devices.

Author contributions

Junke Li designed and executed all major experiments and composed the article draft. Ying Huang: writing – reviewing and editing. Mingming Gao: validation, data curation. Xiao Tan: data curation. Lingru Xia: data curation. Sheng Yang: writing – reviewing and editing. Faxing Wang: writing – reviewing and editing. Songlin Wang: writing – reviewing and editing. Yao Gao: writing – reviewing and editing. Panpan Zhang: conceptualization, writing – reviewing and editing. Xing Lu: funding acquisition, supervision, writing – reviewing and editing.

Conflicts of interest

There are no conflicts to declare.

Data availability

The data supporting this article have been included as part of the SI. See DOI: https://doi.org/10.1039/d5ta04140f.

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (No. 22209051, 22205070, 22475077, 92261204, and 22431005), the Science Foundation of Huazhong University of Science and Technology (3034110102), and the Hubei Provincial Natural Science Foundation of China (2021CFA020). The authors acknowledge the use of the facilities at the Analytical and Testing Center at Huazhong University of Science and Technology.

References

1. Y. Wang, S. Sun, X. Wu, H. Liang and W. Zhang, Nano-Micro Lett., 2023, 15, 78.
2. L. Tang, H. Peng, J. Kang, H. Chen, M. Zhang, Y. Liu, D. H. Kim, Y. Liu and Z. Lin, Chem. Soc. Rev., 2024, 53, 4877.
3. W. Guo, T. Hua, C. Qiao, Y. Zou, Y. Wang and J. Sun, Energy Storage Mater., 2024, 66, 103244.
4. S. Di, X. Nie, G. Ma, W. Yuan, Y. Wang, Y. Liu, S. Shen and N. Zhang, Energy Storage Mater., 2021, 43, 375.
5. S. Higashi, S. W. Lee, J. S. Lee, K. Takechi and Y. Cui, Nat. Commun., 2016, 7, 11801.
6. H. Tian, G. Feng, Q. Wang, Z. Li, W. Zhang, M. Lucero, Z. Feng, Z.-L. Wang, Y. Zhang, C. Zhen, M. Gu, X. Shan and Y. Yang, Nat. Commun., 2022, 13, 7922.
7. Z. Cai, J. Wang and Y. Sun, eScience, 2023, 3, 100093.
8. X. Liu, F. Yang, W. Xu, Y. Zeng, J. He and X. Lu, Adv. Sci., 2020, 7, 2002173.
9. P. Liu, W. Liu, Y. Huang, P. Li, J. Yan and K. Liu, Energy Storage Mater., 2020, 25, 858.
10. X. Xie, S. Liang, J. Gao, S. Guo, J. Guo, C. Wang, G. Xu, X. Wu, G. Chen and J. Zhou, Energy Environ. Sci., 2020, 13, 503.
11. Y. Hao, D. Feng, L. Hou, T. Li, Y. Jiao and P. Wu, Adv. Sci., 2022, 9, 2104832.
12. C. Li, Y. Song, N. Gao, C. Ye, X. Xu, W. Yang and C. Hu, J. Mater. Chem. A, 2024, 12, 5439.
13. W. Fan, H. Wang and J. Wu, eScience, 2024, 4, 100248.
14. M. Zhang, P. Yu, K. Xiong, Y. Wang, Y. Liu and Y. Liang, Adv. Mater., 2022, 34, 2200860.
15. G. Zhang, X. Zhang, H. Liu, J. Li, Y. Chen and H. Duan, Adv. Energy Mater., 2021, 11, 2003927.
16. Y. Li, L. Wu, C. Dong, X. Wang, Y. Dong, R. He and Z. Wu, Energy Environ. Mater., 2023, 6, e12423.
17. J. Li, Q. Lin, Z. Zheng, L. Cao, W. Lv and Y. Chen, Appl. Mater. Interfaces, 2022, 14, 12323.
18. M. Li, Q. He, Z. Li, Q. Li, Y. Zhang, J. Meng, X. Liu, S. Li, B. Wu, L. Chen, Z. Liu, W. Luo, C. Han and L. Mai, Adv. Energy Mater., 2019, 9, 1901469.
19. Z. Zhu, Y. Men, W. Zhang, W. Yang, F. Wang, Y. Zhang, Y. Zhang, X. Zeng, J. Xiao, C. Tang, X. Li and Y. Zhang, eScience, 2024, 4, 100249.
20. Q. Zhao, T. Xu, K. Liu, H. Du, M. Zhang, Y. Wang, L. Yang, H. Zhang, X. Wang and C. Si, Energy Storage Mater., 2024, 71, 103605.
21. Y. Wang, T. Xu, K. Liu, M. Zhang, X.-M. Cai and C. Si, Aggregate, 2024, 5, e428.
22. H. Tian, J.-L. Yang, Y. Deng, W. Tang, R. Liu, C. Xu, P. Han and H. J. Fan, Adv. Energy Mater., 2023, 13, 2202603.
23. F. Xie, H. Li, X. Wang, X. Zhi, D. Chao, K. Davey and S.-Z. Qiao, Adv. Energy Mater., 2021, 11, 2003419.
24. Y. Zhu, G. Liang, X. Cui, X. Liu, H. Zhong, C. Zhi and Y. Yang, Energy Environ. Sci., 2024, 17, 369.
25. Q. Zhang, J. Luan, X. Huang, L. Zhu, Y. Tang, X. Ji and H. Wang, Small, 2020, 16, 2000929.
26. F. Wang, J. Y. Cheong, J. Lee, J. Ahn, G. Duan, H. Chen, Q. Zhang, I. D. Kim and S. Jiang, Adv. Funct. Mater., 2021, 31, 2101077.
27. M. Gao, Z. Wang, Z. Liu, Y. Huang, F. Wang, M. Wang, S. Yang, J. Li, J. Liu, H. Qi, P. Zhang, X. Lu and X. Feng, Adv. Mater., 2023, 35, 2305575.
28. Y. Jiao, Y. Zheng, K. Davey and S.-Z. Qiao, Nat. Energy, 2016, 1, 1.
29. X. Hou, P. Ren, W. Tian, R. Xue, B. Fan, F. Ren and Y. Jin, J. Power Sources, 2024, 603, 234408.
30. Q. Kong, Q. Zhang, B. Yan, J. Chen, D. Chen, L. Jiang, T. Lan, C. Zhang, W. Yang and S. He, J. Energy Storage, 2024, 80, 110322.
31. D. Xiong, C. Liu, Z. Song, X. Hu, W. Deng, H. Hou, G. Zou and X. Ji, Energy Storage Mater., 2024, 71, 103687.
32. Y. Mu, Z. Li, B.-k. Wu, H. Huang, F. Wu, Y. Chu, L. Zou, M. Yang, J. He, L. Ye, M. Han, T. Zhao and L. Zeng, Nat. Commun., 2023, 14, 4205.
33. K. Cychosz Struckhoff, M. Thommes and L. Sarkisov, Adv. Mater. Interfaces, 2020, 7, 2000184.
34. J. Jiang, Z. Shen, J. Qian, Z. Dan, M. Guo, Y. He, Y. Lin, C.-W. Nan, L. Chen and Y. Shen, Nano Energy, 2019, 62, 220.
35. D. Fang, B. Yan, S. Agarwal, W. Xu, Q. Zhang, S. He and H. Hou, J. Mater. Sci., 2021, 56, 9344.
36. L. Wang, Z. Wang, H. Li, D. Han, X. Li, F. Wang, J. Gao, C. Geng, Z. Zhang, C. Cui, Z. Weng, C. Yang, K. P. Loh and Q.-H. Yang, ACS Nano, 2022, 17, 668.
37. M. Zhou, S. Guo, J. Li, X. Luo, Z. Liu, T. Zhang, X. Cao, M. Long, B. Lu, A. Pan, G. Fang, J. Zhou and S. Liang, Adv. Mater., 2021, 33, 2100187.
38. Y. Zhou, X. Wang, X. Shen, Y. Shi, C. Zhu, S. Zeng, H. Xu, P. Cao, Y. Wang, J. Di and Q. Li, J. Mater. Chem. A, 2020, 8, 11719.
39. P. Zhang, Y. Li, G. Wang, F. Wang, S. Yang, F. Zhu, X. Zhuang, O. G. Schmidt and X. Feng, Adv. Mater., 2018, 31, 1806005.
40. Q. Jiang, N. Kurra, C. Xia and H. N. Alshareef, Adv. Energy Mater., 2016, 7, 1601257.
41. L. Han, H. Huang, X. Fu, J. Li, Z. Yang, X. Liu, L. Pan and M. Xu, Chem. Eng. J., 2020, 392, 123733.
42. D. Wang, L. Yan, Y. Zhang, R. Ma, B. Zhang, N. Guo, L. Wang, L. Ai, D. Jia and M. Xu, J. Energy Storage, 2024, 85, 111050.
43. B. Xue, C. Liu, X. Wang, Y. Feng, J. Xu, F. Gong and R. Xiao, Chem. Eng. J., 2024, 480, 147994.
44. C. Hu, P. Liu, Z. Song, Y. Lv, H. Duan, L. Xie, L. Miao, M. Liu and L. Gan, Chin. Chem. Lett., 2025, 36, 110381.
45. F. Yin, K. Lu, H. Feng, B. Xue, L. Sun and R. Xiao, J. Power Sources, 2025, 642, 236955.
46. Y. Yang, D. Chen, H. Wang, P. Ye, Z. Ping, J. Ning, Y. Zhong and Y. Hu, Chem. Eng. J., 2022, 431, 133250.
47. Y. Zhang, P. Xie, C. Jiang and Z. Zou, J. Energy Storage, 2023, 57, 106169.

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