Aramid nanofibers/polyphenylene sulfide nonwoven composite separator fabricated through a facile papermaking method for lithium ion battery

Separator is a vital component in lithium ion battery (LIB) and its property is directly related to cell performance and safety. However, the current widely used polyolefin separator suffers from lower heat resistant and inferior electrolyte wettability. Therefore, more attention has been attracted in the development of high performance separator. In this study, aramid nanofibers (ANFs), poly(p-phenylene terephthalamide), and heat-resistant polyphenylene sulfide (PPS) nonwoven were used to fabricate LIB composite separator by a facile papermaking process, which was abbreviated as ANFs/PPS. It was found that the introduced polar aramid nanofibers in this composite separator significantly regulated the porosity and improved electrolyte wettability, thus being helpful for lithium ion transfer between electrodes, increasing the ionic conductivity and exhibiting better interfacial compatible. These behaviors finally endowed battery with superior rate capability and excellent cycling performance. Moreover, the incorporation of aramid nanofibers in PPS membrane was confirmed to own higher Young's modulus to supply enough anti-deformation ability. In addition, we found the composite separator displayed outstanding thermal stability, flame retardant ability and broader electrochemical window, which would guarantee higher safety during battery operation. Accordingly, ANFs/PPS composite separator will provide a promising potential for application in high power LIB.