Integrating Competitive Li Coordination with Immobilized Anions in Composite Solid Electrolyte for High-Performance Li Metal Batteries.

Poly(vinylidene fluoride) (PVDF)-based polymer electrolytes have attracted widespread attention due to their unique Li transport mechanism. However, their low ionic conductivity and porous structure, as well as residual solvent limit their application at high current densities. Here, a composite solid electrolyte (CSE) is developed by integrating poly(vinylidene-co-trifluoroethylene) [P(VDF-TrFE)] in its all-trans conformation with aminofunctionalized metal-organic framework (ZIF-90-NH). In such a CSE, all F atoms located on one side of the polymer chain, providing fast Li transport channels. Concurrently, the functionalized ZIF-90-NH can effectively anchor the residual N, N-dimethylformamide (DMF) in CSEs while weakening Li-DMF solvent coordination, inducing the rearrangement of Li solvation structure and inhibiting the decomposition of DMF at the interface. Synergistically, ZIF-90-NH can immobilize anions in Li salts, promoting their dissociation. Based on integrating competitive Li coordination with immobilized anions, the obtained CSEs exhibit a high Li transference number (0.77). The full cells with LiFePO cathode can run stably over 400 cycles at 5 C, while the Li || LiNiCoMnO full cells deliver a high capacity retention (>85%) after 200 cycles at a charge cutoff voltage of 4.5 V. This work opens up a new path for building CSEs with high interfacial stability and fast Li transport.