A new electrolyte for LiFePO₄ Li-ion batteries working in a low temperature range

A solvent FEC (Fluoroethylene carbonate) was used to formulate an electrolyte for the operation of a LiFePO₄ cathode by employing a salt of 1M LiPF₆ (Lithium hexafluorophos- phate). The analysis of ion conductivity and CV indicated that the electrolyte with FEC has higher conductivity at low temperature, the solvent FEC start to form solid electrolyte interface (SEI) at 1.6V, so that cell stability is enhanced as that SEI can prevent co-embed of the solvent PC. The results determined by infrared spectrometry showed that the solvent FEC can prevent some solvent's reduction, and form a better SEI on the surface of MCMB. Besides, that SEI has a small resistance at room temperature and low temperature. Their electrochemical performances show that the Li-ion battery containing the electrolyte with FEC has a higher discharge capacity at low temperature.