Lithium Salt Doped Poly(Vinylidene Fluoride)/Cellulose Acetate Composite Gel Electrolyte Membrane for Lithium Ion Battery

In this study, composite gel electrolyte based on Polyvinylidene fluoride (PVDF)/cellulose acetate with the addition of different proportions of lithium nitrate (LiNO₃) is prepared by a simple casting method. Salt doping effects on gel electrolyte membrane is investigated by scanning electron microscopy, X-ray analysis, DSC, FT-IR and TGA analysis. Salt doped gel electrolyte membrane shows a porous structure with a high uptake of 150%. Furthermore, with the addition of 20 wt% salt in the gel electrolyte membrane increase the ion conductivity from 0.21×10^-3 S cm^-1 to 3.0×10^-3 S cm^-1 at room temperature after soaking 1M LiPF₆ EC/DEC liquid electrolyte. As compared with PP 2325 separator, pristine PVDF and PVDF/cellulose acetate gel electrolyte membrane, the salt doped PVDF/cellulose acetate membranes exhibit wide electrochemical window and lower interfacial resistance. Composite gel electrolyte membrane with 10 wt% salt contents possess 100% capacity retention after 100 cycles at 1C rate as compared to PP 2325 separator which shows only 87% capacity retention.