Li–O2 batteries; Oxygen vacancies; Catalyst; High current density; Heterojunction
The application of Li–O2 batteries (LOBs) with ultra-high theoretical energy density is limited due to the slow redox kinetics and serious side reactions, especially in high-rate cycles. Herein, CeO2 is constructed on the surface of Mn2O3 through an interface engineering strategy, and Mn2O3@CeO2 heterojunction with good activity and stability at high current density is prepared. The interfacial properties of catalyst and formation mechanism of Li2O2 are deeply studied by density functional theory (DFT) and experiments, revealing the charge-discharge reaction mechanism of LOBs. The results show that the strong electron coupling between Mn2O3 and CeO2 can promote the formation of oxygen vacancies. Heterojunction combined with oxygen vacancy can improve the affinity for O2 and LiO2 reaction intermediates, inducing formation of thin-film Li2O2 with low potential and easy decomposition, thus improving the cycle stability at high current density. Consequently, it achieved a high specific capacity of 12,545 mAh g−1 at 1,000 mA g−1 and good cyclability of 120 cycles at 4,000 mA g−1. This work thus sheds light on designing efficient and stable catalysts for LOBs under high current density.