The effects of polybenzimidazole nanofiber separator on the safety and performance of lithium-ion batteries: Characterization and analysis from the perspective of mechanism

Polybenzimidazole membrane exhibits a promising application prospect in the high-performance and safe operation of lithium-ion batteries (LIBs). However, the relevant characterization and analysis of their safety mechanism is extremely lacking. Herein, a poly(aryl ether benzimidazole) (OPBI) non-woven fabric is prepared by electrospinning technology as a highly safe separator of LIBs. The characterization and analysis of safety mechanism in terms of thermostability, flame resistance, electrochemical stability, as well as dendrite growth, are investigated. The OPBI membrane shows excellent stability, such as no shrinkage at 200 °C, remaining weight above 54% at 800 °C, even no combustion on fire, electrochemical stability window exceeding 5.75 V vs. Li+/Li. Compared with Celgard 2400 separator, the Li dendrite growth is effectively suppressed by the OPBI membrane due to the excellent interface compatibility with Li anode. The Li/LiFePO4 cells using OPBI membrane deliver outstanding cycling stability (a specific capacity retention rate of 94% over 300 cycles) and excellent rate capacity. The results indicate that the OPBI nanofiber membrane is an intriguing candidate for high-performance and safe LIBs.