Enhanced thermal properties of the solid electrolyte interphase formed on graphite in an electrolyte with fluoroethylene carbonate

The influence of fluoroethylene carbonate (FEC) on the electrochemical and thermal properties of graphite anodes is examined. The dQ/dV graph of graphite/Li cells shows that the electrochemical reduction peak of an electrolyte shifts to higher potential in the presence of FEC. The DSC results for graphite anodes cycled in FEC-containing electrolytes clearly exhibit that an exothermic peak at around 120 °C mostly disappears. It is demonstrated by X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) that SEI formed by the electrochemical reduction of FEC consists of a relatively high proportion of LiF and gives low interfacial resistance for graphite/Li/Li cells.