Li₂O₂ Formation Electrochemistry and Its Influence on Oxygen Reduction/Evolution Reaction Kinetics in Aprotic Li–O₂ Batteries

Aprotic Li–O₂ batteries are regarded as the most promising technology to resolve the energy crisis in the near future because of its high theoretical specific energy. The key electrochemistry of a nonaqueous Li–O₂ battery highly relies on the formation of Li₂O₂ during discharge and its reversible decomposition during charge. The properties of Li₂O₂ and its formation mechanisms are of high significance in influencing the battery performance. This review article demonstrates the latest progress in understanding the Li₂O₂ electrochemistry and the recent advances in regulating the Li₂O₂ growth pathway. The first part of this review elaborates the Li₂O₂ formation mechanism and its relationship with the oxygen reduction reaction/oxygen evolution reaction electrochemistry. The following part discusses how the cycling parameters, e.g., current density and discharge depth, influence the Li₂O₂ morphology. A comprehensive summary of recent strategies in tailoring Li₂O₂ formation including rational design of cathode structure, certain catalyst, and surface engineering is demonstrated. The influence resulted from the electrolyte, e.g., salt, solvent, and some additives on Li₂O₂ growth pathway, is finally discussed. Further prospects of the ways in making advanced Li–O₂ batteries by control of favorable Li₂O₂ formation are highlighted, which are valuable for practical construction of aprotic lithium–oxygen batteries.