Effects of SiO2 Nanoparticles and Diethyl Carbonate on the Electrochemical Properties of a Fibrous Nanocomposite Polymer Electrolyte for Rechargeable Lithium Batteries

In this study, a fibrous nanocomposite polymer electrolyte (NCPE) based on poly(vinylidene fluoride-co-hexafluoropropylene) was prepared through a electrospinning technology. Effects of SiO 2 nanoparticles and diethyl carbonate (DEC) on the electrochemical properties of the fibrous NCPE are investigated by linear sweep voltammetry, cyclic voltammogram and electrochemical impedance spectroscopy. The electrolyte uptake and ionic conductivity of the fibrous NCPE are enhanced due to incorporation of SiO 2 nanoparticles. Addition of DEC into the electrolyte promotes not only the electrochemical stability but also the ionic conductivity of the fibrous NCPE. The fibrous NCPE has a high ionic conductivity up to 3.48 × 10 −3 S cm −1 at 25 °C when it (incorporated with 5 wt% SiO 2 ) absorbs the electrolyte of 1 mol l −1 LiBF 4 /EMIBF 4 -DEC (2:1 in volume). It exhibits good lithium striping and depositing properties during cycling accompanying with a discounted thermally stable temperature of 148 °C. The Li/LiFePO 4 cells using this NCPE membrane as separator exhibit good rate capability and cycling performance, suggesting its promising application in rechargeable lithium batteries.