Polyphenylene Sulfide Separator for High Safety Lithium-Ion Batteries

Abstract

© The Author(s) 2019. Separators with ultra-high strength, superior heat-resistance and excellent electrolyte wettability are in urgent demand for the development of high safety and high-power density lithium-ion batteries. Herein in this paper, specially designed polyphenylene sulfide separator is prepared via thermally induced phase separation using binary diluent to improve the performance of LIBs for the first time. The effect of binary diluent composition on the polyphenylene sulfide separator performance is investigated by both computational simulation and experimental studies respectively. The as-prepared polyphenylene sulfide separator exhibits tortuous and highly porous structure, which endows the separator superior electrolyte wettability. Furthermore, it also results in higher ionic conductivity (1.69 mS cm−1), lithium-ion transference number (0.57) and interfacial stability of the polyphenylene sulfide separator. In particular, the polyphenylene sulfide separator presents excellent thermal dimensional stability (without shrinkage up to 280°C), self-extinguishing and ultra-high strength (tensile strength of 119 MPa, Young’s modulus of 7.55 GPa) benefiting from the high performance polyphenylene sulfide. More importantly, the LiFePO4/Li cell using the polyphenylene sulfide separator shows satisfactory cycling stability (0.064% capacity fading per cycle at 2 C) and superior rate performance. These desirable performances suggest that the polyphenylene sulfide separator is very attractive for high safety and high-power density LIBs.