Li 2 O 2 Formation Electrochemistry and Its Influence on Oxygen Reduction/Evolution Reaction Kinetics in Aprotic Li-O 2 Batteries.

Aprotic Li-O ₂ 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-O ₂ battery highly relies on the formation of Li ₂ O ₂ during discharge and its reversible decomposition during charge. The properties of Li ₂ O ₂ and its formation mechanisms are of high significance in influencing the battery performance. This review article demonstrates the latest progress in understanding the Li ₂ O ₂ electrochemistry and the recent advances in regulating the Li ₂ O ₂ growth pathway. The first part of this review elaborates the Li ₂ O ₂ 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 Li ₂ O ₂ morphology. A comprehensive summary of recent strategies in tailoring Li ₂ O ₂ 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 Li ₂ O ₂ growth pathway, is finally discussed. Further prospects of the ways in making advanced Li-O ₂ batteries by control of favorable Li ₂ O ₂ formation are highlighted, which are valuable for practical construction of aprotic lithium-oxygen batteries.
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