High safety and electrochemical performance electrospun para-aramid nanofiber composite separator for lithium-ion battery

Separators have a significant impact on the electrochemical performance and safety of lithium-ion batteries (LIBs). To date, it is still a great challenge to prepare a single separator that can meet all the requirements for LIBs. Herein, a porous composite membrane based on para-aramid nanofibers (ANFs) via introducing poly (ethylene oxide) (PEO) is successfully prepared by electrospinning and applied in LIB separators. The obtained ANFs/PEO separators are found to exhibit excellent morphology and high porosity, which promote a high electrolyte uptake. Therefore, a battery with the ANFs/PEO separator shows better electrochemical performance to that of the Celgard 2400 separator. More importantly, the tensile strength of ANFs/PEO separators after heat treatment reach 41.52 MPa while maintaining a porosity of 75.85%. At the same time, the thermal stability of ANFs/PEO separators is outstanding, and there is almost no thermal shrinkage at 200 °C for 1 h. Compared with Celgard 2400 separators, ANFs/PEO separators exhibit better electrochemical performance and thermal stability, as well as good mechanical strength and flexibility, achieving a balance between electrochemical performance and safety of LIBs. These results demonstrate that the ANFs/PEO separator with comprehensive performance is promising for high-performance LIBs.