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

Since 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.