Li2O2 oxidation: the charging reaction in the aprotic Li-O2 batteries

Aprotic Li-O-2 battery has attracted a great deal of interest because of its high theoretical energy density that is far beyond what the best Li-ion technologies can achieve. However, the present Li-O-2 batteries suffer from the low energy efficiency that is limited mainly by the high overpotentials required to re-oxidize Li2O2, the discharge product. Over the past few years, considerable research efforts have been devoted to the understanding of the Li2O2 oxidation reactions. Here, we summarize the results obtained from the fundamental study of the Li2O2 oxidation, including its morphology, reaction route, kinetics, the initial location upon oxidation and the charge transport within Li2O2. A better mechanistic understanding of the Li2O2 oxidation reaction will provide a solid foundation for the realization of practical Li-O-2 cells with a higher energy efficiency.