PEO/PLA-based high-temperature organic-inorganic composite solid electrolyte for all-solid-state graphite anode Lithium batteries

As the cornerstone of next-generation energy storage technology characterized by high safety and high energy density, the development of all-solid-state lithium batteries relies critically on the advancement of high-performance composite solid electrolytes (CSEs). In this study, LATP inorganic fillers were incorporated into a PEO/PLA/LiTFSI matrix for the first time to fabricate a novel organic–inorganic composite solid electrolyte (CSE) membrane. Using this membrane, an all-solid-state graphite anode battery with an LFP│CSE│C (graphite) configuration was assembled. The CSE film containing 15 wt% LATP demonstrated superior overall performance, exhibiting a room-temperature ionic conductivity of 1.6 × 10 −4  S/cm. This represents an enhancement of approximately five orders of magnitude compared to the pure PEO/PLA/LiTFSI solid polymer electrolyte. At 60 °C, the ionic conductivity reached 9.6 × 10 −2  S/cm, reflecting a 600 % improvement over its room-temperature value. The electrolyte exhibited an electrochemical stability window of 4.8 V and an ion transference number of 0.7. After 100 cycles, the battery demonstrated excellent cycling durability at 0.2C and 60 °C, retaining 96.5 % of its initial capacity—a 10 % improvement in capacity retention—with a Coulombic efficiency of 99.56 %. The PEO/PLA/LiTFSI/LATP composite solid electrolyte (CSE) represents a promising flexible electrolyte system for all-solid-state lithium batteries, offering a viable strategy for advancing the development of current all-solid-state lithium batteries with graphite anodes.