Studies of Lithium Intercalation into Carbons Using Nonaqueous Electrochemical Cells

TLDR

Li/graphite and Li/petroleum coke cells in a 50:50 propylene carbonate/ethylene carbonate electrolyte undergo irreversible reactions only on the first discharge, caused by electrolyte decomposition that forms a passivating solid electrolyte interphase on the carbon surface. The extent of electrolyte decomposition scales with the carbon electrode’s specific surface area, ceasing once the surface is fully covered by the decomposition film. After the initial cycle, the cells exhibit excellent reversibility and can be cycled without capacity loss.

Abstract

Li/graphite and Li/petroleum coke cells using a in a 50:50 mixture of propylene carbonate (PC) and ethylene carbonate (EC) electrolyte exhibit irreversible reactions only on the first discharge. These irreversible reactions are associated with electrolyte decomposition and cause the formation of a passivating film or solid electrolyte interphase on the surface of the carbon. The amount of electrolyte decomposition is proportional to the specific surface area of the carbon electrode. When all the available surface area is coated with the film of decomposition products, further decomposition reactions stop. In subsequent cycles, these cells exhibit excellent reversibility and can be cycled without capacity loss.