Hexafluorophosphate intercalation into graphite electrode from ethylene carbonate/ethylmethyl carbonate

The electrochemical intercalation of hexafluorophosphate anion into a graphite electrode has been studied in mixed solvents of ethylene carbonate (EC) and ethylmethyl carbonate (EMC). The suppression effect of EC and the favourable effect of EMC on hexafluorophosphate insertion into graphite in these electrolyte solutions have been verified by electrochemical tests, ex situ XRD and in situ Raman. Moreover, the solvation effect on anion in solutions was analyzed by nuclear magnetic resonance. In addition, long-term cycling performance of Li/graphite cells has been obtained.