PVDF-based Comoposite Polymer Electrolyte for Li/LiFePO₄ Batteries

摘要

In order to improve the mechanical strength of the PP/PE/PP membrane, a novel polymer membranewas prepared by introducing nano-SiO2 filled PVDF polymer film. After soaking the liquid electrolyte-1 (1 mol L LiPF6 (DMC:DEC:EC=1:1:1, w/w/w)), the composite polymer electrolyte was obtained andused as the electrolyte for Li/LiFePO4 batteries.The properties of the composite polymerfilm/electrolyte were characterized by scan electronic microscopy, material test machine, scanvoltammetry, electrochemical impedance spectroscopy, constant current charge/discharge test. Theresults showed that the composite polymer film owns higher electrolyte absorption ability (145 %absorbance) and improved mechanical strength than that of PP/PE/PP film. The ionic conductivity-3 -1 reached 1.1210 Scm , and its electrochemical stability window is about 4.5V. At 60 the capacityretention of Li/LiFePO4 batteries with the obtained composite polymer electrolyte as electrolyte was98 % after 100 cycles even at 1C. The excellent cyclability of Li/LiFePO4 batteries at high temperatureshowed that the obtained composite polymer electrolyte could be a possible electrolyte candidate forLi/LiFePO4 batteries used for electric vehicles and hybrid electric vehicles.