Effect of vinylene carbonate as electrolyte additive on cycling performance of LiFePO4/graphite cell at elevated temperature

Effects of film-forming additive on stability of electrode and cycling performance of LiFePO4/graphite cell at elevated temperature were studied. Two 18650 cells with and without VC additive were investigated by galvanostatic cycling, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis and Raman spectroscopy. The results show that in the presence of VC additive, dissolution of Fe from LiFePO4 material is greatly depressed and stability of graphite structure is improved; the additive can not only reduce reaction of electrolyte on surface of LiFePO4 electrode but also suppress reduction of solvent and thickening of the solid electrolyte interface (SEI) layer on graphite surface. Electrolyte with VC is considered to be a good candidate for improving cycling performance of the LiFePO4/graphite cell at elevated temperature.