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

Abstract 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 2 ). 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 2 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 2 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 4 cathode can run stably over 400 cycles at 5 C, while the Li || LiNi 0.7 Co 0.1 Mn 0.2 O 2 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.