Ionic conductivity and electrochemical properties of nanocomposite polymer electrolytes based on electrospun poly(vinylidene fluoride-co-hexafluoropropylene) with nano-sized ceramic fillers

A series of nanocomposite polymer electrolytes (NCPEs) comprising nanoparticles of BaTiO₃, Al₂O₃ or SiO₂ were prepared by electrospinning technique. The nano-sized ceramic fillers were incorporated into poly(vinylidene fluoride-co-hexafluoropropylene) [P(VdF-HEP)] membranes during the electrospinning process. The resultant porous membranes are good absorbent of the liquid electrolyte and exhibit high electrolyte retention capacity. The presence of the ceramic nanoparticles has positive effect on the mechanical properties of the membranes. The ionic conductivity and the electrochemical stability window of the electrospun P(VdF-HFP)-based polymer are enhanced by the presence of the fillers. The cell Li/LiFePO₄ based on the NCPE containing BaTiO₃ delivers a discharge capacity of 164 mAh/g, which corresponds to 96.5% utilization of the active material. In comparison, the performance of Li/LiFePO₄ cells with NCPEs containing Al₂O₃ and SiO₂ was observed to be lower with respective discharge capacities of 153 and 156 mAh/g. The enhanced performance of the BaTiO₃-based-NCPE is attributed mainly to its better interaction with the host polymer and compatibility with lithium metal.