Electrochemical Properties of PP13TFSI-LiTFSI-P(VdF-HFP) Ionic Liquid Gel Polymer Electrolytes (cited: 1)

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 polymerelectrolytes (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-ber 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.