dOffice of Society-Academia Collaboration for Innovation,

Lithium ion is intercalated within graphite to form lithium-graphite intercalation compounds (Li-GICs). Li-GICs have been prepared by reduction of graphite in non-aqueous media, typically ethylene carbonate (EC)-based solutions, containing lithium salts such as LiClO4, LiPF6, LiBF4 etc. The invention of the EC-based electrolyte systems in 1981 was the most important breakthrough for realizing the electrochemical preparation of Li-GICs, which enabled us to use graphite as a negative electrode in commercially available lithium-ion cells. Before this finding, all attempts to electrochemical lithium intercalation within graphite had been unsuccessful because they had been conducted in propylene carbonate (PC)-based solutions, in which only ceaseless solvent decomposition and intensive exfoliation of graphen