Wide-Temperature Flexible Polyurethane Network Reinforced PVDF-HFP Electrolytes for Solid-State Lithium Metal Batteries Operated Under Extreme Conditions

Abstract

Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP)-based solid-state electrolytes have emerged as promising candidates for lithium metal batteries (LMBs) because of their electrochemical stability and mechanical robustness. However, their practical application in LMBs is constrained by intrinsically low ionic conductivity and instability of electrode/electrolyte interfaces, especially at wide-temperature range. This study introduces a wide-temperature flexible polyurethane (PU) into PVDF-HFP to fabricate a solid polymer electrolyte (SPE) with fast Li⁺ transportation kinetics at wide-temperature range. The flexible PU framework endows the SPE with exceptional thermal stability up to 120℃ and compact contact to electrodes at -10℃, as well as high ionic conductivity at RT (4.71×10^-4 S/cm) and -10℃ (9.31×10^-5 S/cm). Solid-state Li||LiFePO₄ batteries using the SPE achieve a capacity retention of 85.4% after 1000 cycles at 0.5 C. Remarkably, the batteries exhibit operational capability across a wide temperature range, maintaining 81.4% capacity retention after 500 cycles at 90℃ (1 C) and stable cyclability at 0℃ with a specific capacity of 100 mAh/g. This study proposes a kind of high-performance solid polymer electrolyte for solid-state LMBs operated under extreme-temperature conditions.