Thermally stable modification of PEO‐based all‐solid‐state electrolytes via a stretching flow field: Constructing a supportive polymer skeleton

Abstract

AbstractSince the advent of all‐solid‐state lithium‐ion batteries (ASSLIBs), they have been widely regarded as the ideal high‐temperature‐resistant energy storage devices. The solid‐state electrolyte, a crucial component, should possess high ionic conductivity, excellent flexibility, and significant mechanical strength. Poly(ethylene oxide)‐based all‐solid‐state polymer electrolytes (PEO‐ASSPE) appear to meet these criteria. However, PEO‐ASSPE exhibits poor stability at elevated temperatures, where localized overheating and internal thermal runaway can lead to battery short‐circuit failure. To address these issues, this study employs a ethylene‐methacrylic acid copolymer (EMAA) as a structural support polymer, blended via a eccentric rotor mixer. The homogeneously dispersed EMAA within the PEO matrix forms an interpenetrating network structure and interacts with other components, significantly enhancing the high‐temperature electrochemical stability of the composite polymer electrolytes (CPEs) while maintaining ionic conductivity. Research has demonstrated that when the EMAA content is 40 wt.%, the resulting CPE‐40EMAA exhibit high ionic conductivity (4.07 × 10−4 S cm−1), a high lithium‐ion transference number (0.564), a broad electrochemical stability window (5.1 V), and excellent high‐temperature lithium metal cycling stability (stable cycling for 800 h at current density of 0.1 mA cm−2), which sufficiently meets the electrochemical performance requirements for ASSPEs in high‐temperature energy storage batteries.