Vinylidenefluoride–hexafluoropropylene copolymers as hybrid electrolyte components for lithium batteries

Hybrid polymer electrolytes based on P(VdF–HFP) copolymers exhibit high ionic conductivity and fair mechanical performances. Two preparation methods are tested in order to optimise the properties of P(VdF–4.5 mol% HFP)-based matrices, activated by different concentrations of a 1.5 M solution of LiN(CF3SO2)2 in an EC/PC mixture: (1) the extraction/absorption procedure; (2) the conventional solvent casting. Conductivity values exceeding 10−4 Ω−1 cm−1 are found in samples containing 60 wt.% of electrolyte solution. In general, the films obtained by casting show a lower conductivity than the samples prepared by the extraction/absorption method, and such a difference decreases when the electrolyte fraction increases.