Dual-functional application of a metal-organic framework in high-performance all-solid-state lithium metal batteries

Lithium metal batteries (LMBs) are one of the most promising candidates for next-generation high energy density batteries. However, the commercialization of LMBs is greatly hindered by several serious problems, including uncontrolled growth of Li dendrites, almost infinite expansion of electrode volume, and the erosion of electrode materials by liquid electrolytes. The present work addresses these issues by proposing a bifunctional Sn metal–organic framework (MOF) that acts as both a precursor of lithiophilic promoter for Li metal anode and an inert filler for polyethylene oxide (PEO)-based solid state electrolyte (SSE). As a result of excellent lithiophilicity, the SnO₂ nanoparticles on carbon derived from Sn-MOF are applied to prepare a composite Li metal anode via molten Li infusion method to obtain excellent interfacial stability and long-term cycling performance. On the other hand, Sn-MOF is added to PEO-based SSE as an inert filler to obtain a composite SSE with a favorable ionic conductivity, outstanding Li⁺ transference number, and wide electrochemical window. The insight into the mechanism of Sn-MOF to improve the ionic conductivity of PEO-based electrolyte has been revealed by combined experimental analysis and first-principles calculations. An all-solid-state flexible LMB employing the optimal composite anode and SSE is demonstrated to attain an impressive electrochemical performance and the capability of powering actual devices.