Rapid Ion Transport Induced by the Enhanced Interaction in Composite Polymer Electrolyte for All-Solid-State Lithium-Metal Batteries

High-quality solid electrolyte is the key to developing high-performance all-solid-state lithium-metal batteries (ASSLMBs). Herein, we report a thin composite polymer electrolyte (CPE) based on nanosized Li6.4La3Zr1.4Ta0.6O12 (N-LLZTO) and the PVDF-HFP matrix through a simple film-casting method. N-LLZTO induces partial dehydrofluorination of the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) matrix that activates the coordination of Li+ with PVDF-HFP and LLZTO due to Lewis acid-base interactions, which facilitates dissociation of lithium salt to increase the Li+ carrier density. As a result, the as-fabricated composite polymer electrolyte with a 20 wt % N-LLZTO (CPE-20) membrane possesses high ionic conductivity (1.7 × 10-4 S cm-1), a high lithium-ion transference number (0.57), a wide electrochemical window (∼4.8 V), and good thermal stability. Moreover, the CPE-20 membrane displays excellent electrochemical stability to suppress the lithium dendrite and serves more than 2000 h. The solid-state Li|CPE-20|LiFePO4 pouch cells exhibit excellent cycling and rate performance, as well as high energy density. This study presents an effective strategy to design promising solid-state electrolyte for next-generation ASSLMBs.