Preparation, Thermal Stability and Electrochemical Properties of LiODFB

Abstract

Lithium difuoro(axalato)bonate (LiODFB) was synthesized in dimethyl carbonate solvent and purified by the method of solventing-out crystallization. The structure characterization and thermal stability of LiODFB was performed by Fourier transform infrared (FTIR) spectrometry, nuclear magnetic resonance (NMR) spectrometry and thermogravimetric analyzer (TGA). LiODFB was exposed to 50% humidity air at 25°C for different time, then dried at 80°C for 12h, and the electrochemical properties of the cells using 1 mol/L dried LiODFB in ethylene carbonate + dimethyl carbonate + ethyl(methyl)carbonate were investigated. The results show that, pure crystallization LiODFB has been obtained; it has good thermal stability with a thermal decomposition temperature of 248°C; exposed to humidity air, it is firstly converted into LiODFB•H2O; with the exposed time increasesing, more and stronger impurity peaks in the XRD patterns of LiODFB are observed, both the discharge specific capacity and the capacity retention decrease gradually