A high temperature operating nanofibrous polyimide separator in Li-ion battery

Separators possessing thermal stability are highly desired to meet the requirement of application in high power lithium batteries. In this paper, the thermosetting polyimide (PI) nano-fibers based nonwoven separators have been developed by electrospining technique and followed by thermal imidization and mechanical pressing with improved thermal stability and considerable mechanical strength. The high concentration of tortuous nanopores structure and intrinsic chemical configuration lead to good ionic transport and improved electrolyte wettability. The electrochemical characterization at high temperature of 120°C demonstrates that the LiBOB/PC soaked polyimide nonwovens is an excellent electrolyte system for high temperature operation owing to possessing high oxidative potential, excellent lithium deposition-stripping performance and considerable ionic conductivity. The cells using LiBOB/PC soaked polyimide nonwovens as separator still exhibit stable charge–discharge profiles with quantitative coulumbic efficiency and satisfactory cyclability at 120°C. The superior electrochemical performance at high temperature could endow these polyimide nonwovens promising alternative to PP separators for high power or high temperature application with superior safety characteristic. ► Polyimide nonwovens show improved thermal stability. ► LiBOB/PC soaked polyimide nonwoven behaves as an electrolyte at 120°C. ► The cells using polyimide nonwovens can operate at 120°C.