Intercalation of anions into graphite electrode from butylene carbonate in activated carbon/graphite hybrid capacitors

The solvation of anions with organic solvent and its electrochemical intercalation into graphite is a significant research orientation in the electrochemical energy storage. Butylene carbonate (BC), a common solvent with higher oxidation resistance compared with ethylene carbonate (EC) and propylene carbonate (PC), is profitable in studying anion-graphite intercalation compounds (AGICs). In this paper, the electrochemical intercalation behaviors of three representative anions (BF4−, ClO4− and PF6−) in BC solution were studied and the solvation states of these anions were characterized by electrochemical in situ and ex situ techniques. The interpretation of results illuminated that all three anions were able to intercalate into graphite with the similar reversibility but different solvation state, and the conclusive role that solvent played in the intercalation process was also discovered.