Electrochemical Properties of Ionic Liquid Composite Poly(ethylene oxide)(PEO) Solid Polymer Electrolyte

In this study, we prepared an ionic liquid composite solid polymer electrolyte (PEO-LiTFSI-Pyr(14)TFSI) with poly(ethylen oxide), lithium bis(trifluoromethanesulfonyl) imide, N-butylN- methylpyrrolidinium bis(trifluoromethanesulfonyl) imide by blending-cross linking process. Although the PEO-LiTFSI-Pyr(14)TFSI composite solid polymer electrolyte displayed a small peak at 4.4 V, it had high electrochemical oxidation stability up to 5.7 V. Ionic conductivity of the PEO-LiTFSI-Pyr(14)TFSI composite solid polymer electrolyte increased with increasing temperature from 10(-6) S cm(-1) at 30 degrees C to 10(-4) S cm(-1) at 70 degrees C. To investigate the electrochemical properties, the PEO-LiTFSI-Pyr(14)TFSI composite solid polymer electrolyte assembled with LiFePO4 cathode and Li-metal anode. At 0.1 C-rate, the cell delivered 40 mAh g(-1) for 30 degrees C, 69.8 mAh g(-1) for 40 degrees C and 113 mAh g(-1) for 50 degrees C, respectively. The PEO-LiTFSI-Pyr(14)TFSI solid polymer electrolyte exhibited good charge-discharge performance in Li/SPE/LiFePO4 cells at 50 degrees C.