Efficient Modulation of Electron Pathways by Constructing a MnO 2- x @CeO 2 Interface toward Advanced Lithium-Oxygen Batteries.

A major challenge for Li-O 2 batteries is to facilely achieve the formation and decomposition of the discharge product Li 2 O 2 , 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- x @CeO 2 heterostructure on the porous carbon matrix. When it was used as a cathode for Li-O 2 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 Li 2 O 2 interacts with the MnO 2- x @CeO 2 interface. Apart from the electronic ladders formed between MnO 2- x 3d and CeO 2 4f orbitals, which can act as a highly efficient "electron transfer expressway", the specific adsorption of MnO 2- x and CeO 2 with Li 2 O 2 molecules contributes to the enhanced anchoring force of Li 2 O 2 and delocalization of the electron cloud on the Li-O bond. Thanks to the constructed heterostructure and synergistic effect, filmlike Li 2 O 2 can be formed through a surface pathway, and when charging, it accelerates the separation of electrons and Li + in Li 2 O 2 , thus achieving fast redox kinetics and low overpotential.