Hybrid gel polymer electrolyte for high-safety lithium-sulfur batteries

A hybrid nanofiber PVDF-HFP polymer matrix with dispersed SiO2 nanoparticles was prepared by electrospinning, and 1 M lithium bis(trifluoromethysulfonyl)imide (LiTFSI)/1-propyl-3-methylimidazolium bis(trifluoromethysulfonyl)imide (PMImTFSI) was incorporated in the hybrid polymer matrix to produce a polymer gel electrolyte for lithium-sulfur batteries. The PMImTFSI-based hybrid gel polymer electrolyte (ILGPE) reduced the concentration of Li+-coordinated TFSI, and the incorporation of PMImTFSI increased the alpha-phase content of PVDF-HFP, reducing polymer crystallinity. In addition, ILGPE showed high ionic conductivity, high oxidation potential ( > 5.0 V vs. Li/Li+), and low flammability. The Li/S battery utilizing ILGPE showed a high initial discharge capacity of 1029 mAh g(-1) and maintained a stable capacity of 885 mAh g(-1) after 30 cycles at a current rate of 0.1 C.