Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (7): 1351-1358.doi: 10.3866/PKU.WHXB201505121

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Synthesis and Electrochemical Performance of Plastic Crystal Compound-Based Ionic Liquid

ZENG Yu-Qun, GUO Yong-Sheng, WU Bing-Bin, HONG Xiang, WU Kai, ZHONG Kai-Fu   

  1. Research Institute, Ningde Amperex Technology Limited, Ningde 352100, Fujian Province, P. R. China
  • Received:2014-12-22 Revised:2015-05-11 Published:2015-07-08
  • Contact: ZHONG Kai-Fu


Highly pure plastic crystal, 1-ethyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (P12TFSI), was synthesized and purified by an easily industrializable recrystallization method. The P12TFSI/LiFSI ionic liquid was obtained by mixing P12TFSI with 30% (molar fraction, x) LiFSI. Electrochemical characterization methods including cyclic voltammetry, constant voltage polarization and charge/discharge at constant current were used to investigate the electrochemical window, stability vs Al corrosion, and battery performance of the ionic liquid.Awide electrochemical window of 5.00 V, non-corrosion of theAl current collector, and 0.92mS·cm-1 of ionic conductivity at room temperature were observed. LiCoO2/Li batteries assembled using this ionic liquid electrolyte showed good charge-discharge characteristics and cycle performance, comparable with those of carbonate-based electrolyte at low rate. The specific capacity of the LiCoO2 remained 175 mAh·g-1 after 20 cycles (95.1% capacity retention) despite cycling at a high voltage up to 4.50 V. These results indicate that the plastic crystal-based ionic liquid P12TFSI/LiFSI could be potentially applied in high-energy density lithium secondary batteries.

Key words: Lithium ion battery, Plastic crystal, Ionic liquid, Pyrrolidinium, High voltage


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