Enhanced Wettability of a PTFE Porous Membrane for a High-Temperature Stable Lithium-Ion Battery Separator

A hydrophobic poly(tetrafluoroethylene) (PTFE) porous membrane was modified into a hydrophilic lithium-ion battery (LIB) separator with a higher affinity to the electrolyte via the hybrid consisting of a cationic fluorocarbon surfactant (FCS), polyethylenimine (PEI), and tetraethyl orthosilicate (TEOS), which can be in-situ biomineralized into SiO2 nanoparticles. The obtained PTFE/FCS-PEI-SiO2 separator showed a dynamic electrolyte contact angle, which decreased from 50.3 degrees to 0 degrees within 4 s, along with 215 % of electrolyte uptake. The ionic conductivity and the interfacial resistance were 9.12 mS cm(-1) and 228.8 omega, respectively. In addition, the cell equipped with the separator showed a capacity of 163.7 mAh g(-1) at a current density of 0.2 C. Notably, the cell with the separator displayed good high-temperature stability.