Solvent dramatically affects the behavior of anion intercalation into graphite electrode in dual-ion batteries (DIBs). Our previous studies have confirmed that the intercalation of ethylene carbonate (EC) solvated PF6- is considerably suppressed. However, in this letter, we showthat EC can apparently co-intercalate with PF6- into graphite electrode once ethyl methyl carbonate (EMC) is involved inside. In situ X-ray diffraction (in situ XRD), ex situ XRD, fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS) have been carried out to clarify the underlying reason. (C) 2019 The Electrochemical Society.