Electrospun PVA/SiO2 separator membranes were presented and their electrochemical performance was evaluated for use in Li-ion batteries. Polyvinyl alcohol (PVA) was used to prepare nanofiber based membranes due to advantages such as low cost, water solubility, and biodegradability. Sol gel technique was employed to introduce SiO2 in PVA nanofibers. It was found that PVA separator membranes had superior electrochemical properties with highly porous structure. Introducing SiO2 further improved porosity, liquid electrolyte uptake, as well as ionic conductivity, and reduced interfacial resistance. Furthermore, when PVA/SiO2 separator membranes were assembled into lithium/lithium iron phosphate cells, higher cycling and C-rate performance was observed compared to those using commercial microporous polyolefin membrane.