Performance evaluation of electrospun polyimide non-woven separators for high power lithium-ion batteries

• Electrospun polyimide (PI) non-woven separator shows excellent thermal stability.
• Effect of imidization temperature on tensile strength of PI separator is studied.
• Batteries with PI separator show excellent electrochemical performance.
• PI separator is of great prospect in application in high lithium ion battery.

The performance of polyimide (PI) non-woven separator used in high power lithium ion battery is investigated to evaluate the feasibility of its industrialized application. PI non-woven separator is prepared via an electrospinning method, and electrospinning process parameters are controlled to get a fibrous membrane consisting of bead-free, uniformly dispersed thin fibers with an average diameter of about 491 nm. The as prepared separator with a porosity higher than 90% and relatively high electrolyte uptake exhibits excellent thermal stability without obvious shrinkage at 500 °C, and shows sufficient tensile strength of 11 MPa to meet the demand of battery assembly and usage. Laminated lithium-ion battery pack assembled with the PI non-woven separators shows a capacity retention ratio of about 33.6% at super high discharge rate of 28.8 C, and the capacity remains 99.66% after 320 cycles at 5 C rate, exhibiting excellent high-rate discharge capacity and favorable cycling performance, much superior to that of the battery pack assembled with the Celgard polyethylene (PE) separators. The results open great opportunities for the industrialized application of PI electrospun non-woven separator.