Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (01): 78-84.doi: 10.3866/PKU.WHXB20110112

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Cathodic and Thermal Stabilities of the P(VdF-HFP)-Based Ionic Liquid Composite Polymer Electrolyte

CUI Wen-Yu, AN Mao-Zhong, YANG Pei-Xia, ZHANG Jin-Qiu   

  1. School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001, P. R. China
  • Received:2010-09-20 Revised:2010-10-28 Published:2010-12-31
  • Contact: AN Mao-Zhong E-mail:mzan@hit.edu.cn
  • Supported by:

    The project was supported by the Natural Science Foundation of Heilongjiang Province, China (B2007-05).

Abstract:

We report on a composite polymer electrolyte containing the ionic liquid 1-ethyl-3- methylimidazolium hexafluorophosphate (EMIPF6). This composite polymer electrolyte is based on the poly(vinylidene fluoride-co-hexafluoropropylene) (P(VdF-HFP)) polymer matrix and is a potential electrolyte for use in lithium ion batteries. The ionic conductivity of the composite polymer electrolyte was measured by electrochemical impedance spectroscopy (EIS). Linear sweep voltammetry (LSV) was performed to investigate the electrochemical stability window of the polymer electrolyte. The thermal properties for the composite polymer electrolyte were also characterized by thermogravimetry (TG) and by a flammability test. The results show that the presence of the EMIPF6 ionic liquid increases the ion transport properties greatly but a better cathodic stability is only obtained by the addition of organic additives such as ethylene carbonate-propylene carbonate (EC-PC), which extends the cathodic stability to 0.3 V. This corresponds to an electrochemical stability window of 0.3-4.3 V. The selected Li4Ti5O12 anode and LiCoO2 cathode materials exhibit acceptable electrochemical performance in combination with the prepared P(VdF-HFP)/ LiPF6/EMIPF6/EC-PC composite polymer electrolyte. At a charge-discharge rate of 0.1C, Li/LiCoO2 and Li/ Li4Ti5O12 have reversible capacities of 130 and 144 mAh·g-1, respectively. However, the corresponding thermal performance is suppressed because of the presence of organic additives.

Key words: Lithium ion battery, Ionic liquid, Composite polymer electrolyte, Cathodic stability, Thermal stability

MSC2000: 

  • O646