Composite of a nonwoven fabric with poly(vinylidene fluoride) as a gel membrane of high safety for lithium ion battery

Abstract

A composite membrane of a nonwoven fabric with poly(vinylidene fluoride) exhibiting high safety (self-extinguishing), good mechanical property and low cost is reported. The ionic conductivity of the as-prepared gel membrane saturated with 1 mol l⁻¹ LiPF₆ electrolyte at ambient temperature can be up to 0.30 mS cm⁻¹, higher than that of the corresponding well-used commercial separator (Celgard 2730), 0.21 mS cm⁻¹. Moreover, the lithium ion transference in the gel membrane at room temperature is almost twice that in the commercial separator. Furthermore, the absorbed solvent is difficult to evaporate at elevated temperature. Its electrochemical performance is evaluated by using a LiFePO₄ cathode. The obtained results suggest that this gel-type composite membrane is very attractive for large-capacity battery systems requiring high safety and low cost.