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

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-NH₂). 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-NH₂ 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-NH₂ 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 LiFePO₄ cathode can run stably over 400 cycles at 5 C, while the Li || LiNi_0.7Co_0.1Mn_0.2O₂ 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.