A multifunctional aramid-reinforced PVDF solid electrolyte for thermally robust lithium metal battery

Developing safe and thermally robust solid-state electrolytes is critical to overcoming the safety risks and performance bottlenecks of conventional lithium batteries, especially at high temperatures. Herein, we report a composite solid polymer electrolyte (SPE) prepared by incorporating a high-performance aramid polymer, poly(m-phenylene isophthalamide) (PMIA), into a poly(vinylidene fluoride) (PVDF) matrix. PMIA plays a critical, multifunctional role, which forms a robust thermal skeleton that maintains structural integrity up to 150 °C, while its polar groups immobilize anions to significantly elevate the Li⁺ transference number to 0.61 and promote a stable, robust solid electrolyte interphase (SEI) that suppresses dendrite growth. These intrinsic advantages translate directly to enhanced electrochemical performance, especially under thermal conditions. The LiFePO₄ (LFP)/Li battery employing the composite electrolyte sustains no obvious capacity decay for over 350 cycles at 30 °C and a high capacity retention of ∼97 % for over 150 cycles at 75 °C. This work demonstrates that incorporating multifunctional aramid additives is an effective strategy for developing next-generation, high-safety solid-state batteries for high-temperature applications.