Boosting safety and performance of lithium-ion battery enabled by cooperation of thermotolerant fire-retardant composite membrane and nonflammable electrolyte

Developing nonflammable electrolytes is regarded as a convenient strategy to solve the combustion problem of lithium-ion batteries (LIBs), but its influences are limited by the severe shrinkage and high combustibility of polyolefin separators at elevated temperatures. Herein, an intrinsically thermotolerant and fire-resistant nanoCaCO(3)-based composite membrane (CPVH) is designed rationally. The CPVH membrane presents superior thermal stability (barely visible shrinkage at 300?degrees C), excellent nonflammability and extremely low heat release (similar to 11% as much as PP). Moreover, the alkaline nano-CaCO3 can neutralize hydrofluoric acid that inevitably exists in LiPF6-based electrolytes, guaranteeing the long-term stability of interfacial layers. Noticeably, LiFePO4/Li battery with CPVH membrane delivered a discharge capacity of 133.6 mAh g(-1) at 0.5C, along with a capacity retention of 93.0% and a coulombic efficiency of 99.9% after 650 cycles. Additionally, harsh safety tests of the battery demonstrate stable circuit safety at a high temperature of 150 degrees C and a significantly low heat release during thermal runaway. Significantly, the LiFePO4/CPVH/graphite full battery showed good cycling stability with a capacity retention of 78.4% and an average coulombic efficiency of 98.0% at 120 degrees C and 2C after 100 cycles. By combining CPVH composite membrane and nonflammable electrolyte, both safety and cycling performance of LIBs were improved completely.