Self-Catalyzed Rechargeable Lithium-Air Battery by in situ Metal Ion Doping of Discharge Products: A Combined Theoretical and Experimental Study

Lithium-air battery has emerged as a viable electrochemical energy technology; yet a substantial overpotential is typically observed, due to the insulating nature of the discharge product Li2O2 that hinders the reaction kinetics and device performance. Furthermore, finite solid-solid/-liquid interfaces are formed between Li2O2 and catalysts and limit the activity of the electrocatalysts in battery reactions, leading to inadequate electrolytic efficiency. Herein, in-situ doping of Li2O2 by select metal ions is found to significantly enhance the lithium-air battery performance, and Co2+ stands out as the most effective dopant among the series. This is ascribed to the unique catalytic activity of the resulting Co-O-x sites towards oxygen electrocatalysis, rendering the lithium-air battery self-catalytically active. Theoretical studies based on density functional theory calculations show that structural compression occurs upon Co2+ doping, which lowers the energy barrier of Li2O2 decomposition. Results from this study highlight the significance of in situ electrochemical doping of the discharge product in enhancing the performance of lithium-air battery.