A high-strength PPESK/PVDF fibrous membrane prepared by coaxial electrospinning for lithium-ion battery separator

Electrospinning fibrous membranes have attracted a great deal of attention because of their advantages, including uniform pore size, large ratio surface area, and high porosity. For extended application in lithium-ion battery, it is essential to further improve their electrochemical, mechanical, and thermal properties. In this work, a new poly (phthalazine ether sulfone ketone) (PPESK)/polyvinyli-denefluoride (PVDF) core/shell fibrous membrane was fabricated via the coaxial electrospinning technique, followed by hot press. The PPESK/PVDF membrane hot pressed at 160°C exhibits excellent comprehensive performance, including large porosity (80%), high electrolyte uptake (805%), and excellent thermal stability (at 200°C). Moreover, due to the improved bonding effect derived from the solidification of the PVDF shell layer after the hot press, the mechanical property of the membrane is effectively enhanced. The electrochemical tests also indicate that the PPESK/PVDF membrane shows larger ionic conductivity and lower interfacial resistance when compared with commercial microporous polypropylene separator. In addition, simulated cells assembled with the PPESK/PVDF membrane present superior discharge capacity, stable cycle performance, and excellent rate capability. Therefore, the hot-pressed coaxial PPESK/PVDF fibrous membrane has the potential to be a promising candidate as the separator for high-performance lithium-ion battery.