Low-temperature-resilient polymer electrolytes for high-performance quasi-solid lithium batteries

Solid-state lithium batteries are promising next-generation energy storage systems due to their high safety and energy density. However, the poor low-temperature performance of solid-state electrolytes remains a critical challenge. Herein, we present a facile and scalable approach for synthesizing a low-temperature-resilient polymer electrolyte based on ethylene-vinyl acetate, leveraging its unique molecular structure for enhanced lithium-ion transport. The ethylene-vinyl acetate polymer electrolyte (EPE) demonstrates a high ionic conductivity of 5.13×10−4 S cm−1 at room temperature and retains a remarkable conductivity of 2.72×10−5 S cm−1 at −40 °C. This superior performance is attributed to the synergistic interaction between the ester functional groups of ethylene-vinyl acetate and lithium salts, which reduces the ion dissociation energy barrier and facilitates efficient ion migration. The EPE enables stable lithium plating/stripping cycling for over 3000 h at −40 °C and supports the long-term cycling of LiFePO4-based full cells at −40 °C for over 900 cycles. This work highlights the potential of cost-effective, scalable EPEs for next-generation solid-state lithium batteries, particularly in extreme environmental conditions.