Preparation and properties of the polymer electrolyte of PVDF-HFP grafted with PEG

A homogeneous microporous polymer electrolyte of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) grafted with polyethylene glycol (PEG) is prepared by extraction. The prepared polymer electrolyte is characterized, and button cells with the grafting copolymer electrolyte are assembled and tested. The results show that PVDF-HFP grafted with PEG has higher liquid absorption, liquid electrolyte retention and conductivity in contrast with the pure PVDF-HFP. The conductivity (at 20°C) of PVDF-HFP and PVDF-HFP-g-PEG is 2.60 × 10^-3 S/cm and 3.28 × 10^-3 S/cm, respectively. The initial discharge capacity of the cell is 119.3 mAh/g at 0.2 C. During the 50 cycles the charge-discharge efficiency is about 99% with the initial discharge capacity of 120.7 mAh/g and the terminal discharge capacity of 115.9 mAh/g. While the discharge capacity at 0.5 C, 1 C and 2 C is 96.2%, 94.5% and 81.3%, respectively, of the discharge capacity at 0.2 C.