Efficient Modulation of Electron Pathways by Constructing a MnO_2-@CeO₂ Interface toward Advanced Lithium-Oxygen...

A major challenge for Li-O₂ batteries is to facilely achieve the formation and decomposition of the discharge product Li₂O₂, and the development of an active and synergistic cathode is of great significance to efficiently accelerate its formation/decomposition kinetics. Herein, a novel strategy is presented by constructing a MnO_2-@CeO₂ heterostructure on the porous carbon matrix. When it was used as a cathode for Li-O₂ batteries, excellent electrochemical performances, including low overpotential, large discharge capacity, and superior cycling stability were obtained. Series theoretical calculations were conducted to reveal the mechanism for the reversible battery reactions and explain how Li₂O₂ interacts with the MnO_2-@CeO₂ interface. Apart from the electronic ladders formed between MnO_2- 3d and CeO₂ 4f orbitals, which can act as a highly efficient "electron transfer expressway", the specific adsorption of MnO_2- and CeO₂ with Li₂O₂ molecules contributes to the enhanced anchoring force of Li₂O₂ and delocalization of the electron cloud on the Li-O bond. Thanks to the constructed heterostructure and synergistic effect, filmlike Li₂O₂ can be formed through a surface pathway, and when charging, it accelerates the separation of electrons and Li⁺ in Li₂O₂, thus achieving fast redox kinetics and low overpotential.