Solid polymer electrolytes incorporating Zn-based metal–organic frameworks for advanced all-solid-state lithium metal batteries

Abstract

Solid Polymer electrolytes hold great promise for enhancing the safety and energy density of lithium-ion batteries. Nonetheless, their inherently poor ionic conductivity and Li dendrite suppression capability present significant barriers to large-scale practical application. Here, we introduce a novel solid polymer electrolyte (SPE) consisting of a metal–organic framework (Zn-MOF), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). The incorporation of Zn-MOF decreases the crystallinity of the polymer, while concurrently enhancing the dissociation of lithium salts. The PZM-10, with 10 wt% Zn-MOF, demonstrates a high room temperature ionic conductivity of 6.65 × 10⁻⁴ S cm⁻¹, a Li⁺ transference number of 0.42, and a wide electrochemical stability window of 4.8 V. Moreover, the incorporation of Zn-MOF improves the interfacial compatibility between the SPE and the Li metal anode, effectively suppressing dendrite growth. The Zn-MOF-based lithium symmetric cells exhibit steady cycling performance for over 1000 cycles at a current density of 0.1 mA cm⁻² at room temperature. The assembled LFP/PZM-10/Li cell demonstrates superior electrochemical performance, exhibiting a discharge capacity of 165.7 mA h g⁻¹ at 0.1 C at room temperature. Moreover, it retains 89% of its capacity after 400 cycles at 0.5 C under room temperature. Furthermore, the cell demonstrates excellent high-temperature stability, retaining 92% of its capacity after 300 cycles at 3 C and 100 °C. In addition, the outstanding safety performance exhibited by the scaled-up pouch cell highlights the significant potential for its application in advanced all-solid-state lithium metal batteries.