First-principles study of the oxygen reduction reaction by lithium on metal and carbon surfaces

Abstract

The reduction of O 2 by lithium (Li-ORR) is the key lectrochemical process in Li-air batteries. So far experiments have yielded little information regarding the nature of the active site and reaction mechanism. Periodic density functional theory calculations have been carried out to investigate the mechanism of the Li-ORR on several transition metals and carbon structures. The reactivity on the metal surfaces, including Pt and Au, is characterized by O-O bond dissociation and the formation of LixO aggregates, with reversible potentials of 1.9-2.1 V. Graphitic carbon can exhibit both the inert basal plane and highly reactive under-coordinated carbons. The former limits O 2 reduction to 1.2 V, while the latter are capable of catalyzing O 3 reduction at up to 2.3 V.