Silica/polyacrylonitrile hybrid nanofiber membrane separators via sol-gel and electrospinning techniques for lithium-ion batteries

Silica/polyacrylonitrile (SiO₂/PAN) hybrid nanofiber membranes were fabricated by using sol-gel and electrospinning techniques and their electrochemical performance was evaluated for use as separators in lithium-ion batteries. The aim of this study was to design high-performance separator membranes with enhanced electrochemical performance and good thermal stability compared to microporous polyolefin membranes. In this study, SiO₂ nanoparticle content up to 27 wt% was achieved in the membranes by using sol-gel technique. It was found that SiO₂/PAN hybrid nanofiber membranes had superior electrochemical performance with good thermal stability due to their high SiO₂ content and large porosity. Compared with commercial microporous polyolefin membranes, SiO₂/PAN hybrid nanofiber membranes had larger liquid electrolyte uptake, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. SiO₂/PAN hybrid nanofiber membranes with different SiO₂ contents (0, 16, 19 and 27 wt%) were also assembled into lithium/lithium iron phosphate cells, and high cell capacities and good cycling performance were demonstrated at room temperature. In addition, cells using SiO₂/PAN hybrid nanofiber membranes with high SiO₂ contents showed superior C-rate performance compared to those with low SiO₂ contents and commercial microporous polyolefin membrane.