N-Methyl-N-propylpiperidiniumbis（trifluoromethanesulfonyl）imide （PP13TFSI）, bis（triflu- oromethanesulfonyl）imide lithium salt （LiTFSI）, and poly（vinylidene difluoride-co- hexafluoropropylene） （P（VdF-HFP）） were mixed and made into ionic liquid gel polymer electrolytes （ILGPEs） by solution casting. The morphology of ILGPEs was observed by scanning electron microscopy. It was found that the ILGPE had a loosened structure with liquid phase uniformly distributed. The ionic conductivity, lithium ion transference num- bet and electrochemical window were measured by electrochemical impedance spectroscopy, chronoamperometric and linear sweep voltammetry. The ionic conductivity and lithium ion transference number of this ILGPE reached 0.79 mS/cm and 0.71 at room temperature, and the electrochemical window was 0 to 5.1 V vs. Li＋/Li. Battery tests indicated that the ILGPE is stable when being operated in Li/LiFePO4 batteries. The discharge capacity maintained at about 135, 117, and 100 mAh/g at 30, 75, and 150 mA/g rates, respectively. The capacity retentions were almost 100% after 100 cycles without little capacity fading.
