Unitized Configuration Design of Thermally Stable Composite Polymer Electrolyte for Lithium Batteries Capable of Working Over a Wide Range of Temperatures

Solid‐state electrolytes that can meet the requirements of high‐safety lithium batteries at high temperature aroused much attention in electrochemical energy storage.Nevertheless, the low ionic conductivity at ambient temperature and poor mechanical strength limit their practical applications. Through unitized configurationdesign, herein, a unique safe and flexible composite polymer electrolyte membrane comprising of inorganic ceramic particles (Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 , LLZNO), polyvinylidene fluoride (PVDF), and lithium perchlorate (LiClO 4 ) are fabricated. Benefitting from the strongly coupled effects via interfacial chemical reactions and the synergistic effects between LLZNOand PVDF, the LLZNO‐based composite electrolyte wetted by ionic liquid exhibits a high ionic conductivity of 1.5 × 10 −3 S cm −1 at 25 °C. Moreover, the electrolyte is able to be thermally stable at relatively high temperatures. A LiFePO 4 (+) // Li (−) lithium battery using the as‐prepared LLZNO‐based composite electrolyte achieves a good electrochemical stability at ambient temperature, 80 °C and even 120 °C. This work provides an effective way to the fabrication of high‐performance, flexible electrolyte membranes for lithium batteries and other energy‐storage devices that are capable of working over a wide range of temperatures