Polyphenylene sulfide nonwoven-based composite separator with superior heat-resistance and flame retardancy for high power lithium ion battery

In this study, a new alternative nonwoven based on engineering plastic polyphenylene sulfide (PPS) was explored as the support to construct high performance and safety separator for the first time. By the method of physical coating polymer poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) and inorganic nanoparticle SiO2 on the support, the designed composite separator was successfully obtained for lithium ion battery. Systematic investigations ranging from physical properties, thermal properties to electrochemical performances were carried out. It was found that compared with commercialized polyolefin separator, PPS nonwoven-based composite separator possessed higher porosity, air permeability, improved electrolyte wettability and electrolyte uptake, thus being helpful for lithium ion transfer between electrodes and increasing the ionic conductivity. These behaviors accordingly endowed battery with superior discharge capacity at various discharge current rates from 0.2 C to 2 C. Moreover, the composite separator was observed to exhibit excellent dimensional stability even after thermal treatment at 250 °C and present good flame retardant ability. The afore-mentioned outstanding performances of PPS nonwoven-based composite separator would shed light on the development of high power lithium ion battery.