Effect of Fluoroethylene Carbonate Additive on Low Temperature Performance of Li-Ion Batteries

The effects of Fluoroethylene carbonate (FEC) on the low temperature performance of Li-ion batteries were evaluated. By addition of 2 v% FEC into a commercial ternary electrolyte, the initial lithium intercalation capacity (graphite/Li model cell) was remarkably improved by approximately 50% and the voltage plateau of the cell was lowered by about 0.2 V at −20°C. This is maybe attributed to a reduced charge transfer resistance and a lowered SEI film resistance with a richer LiF phase formed on the graphite electrode by Tafel polarization, AC impedance and X-ray photoelectron spectroscopy (XPS) analysis.