Mechanisms of Oxygen Reactions in Lithium–Air Batteries

The complicated O₂ reactions at the battery's positive electrode hinder the development of Li–air and Li–O₂ batteries. The oxygen reduction reaction (during battery discharge) and the oxygen evolution reaction (during battery charge) are still not fully elucidated, and more than one mechanism has been proposed for each process. These mechanisms greatly depend on the electrolyte's physicochemical properties, which opens the possibility of favoring a more desired one. Nonetheless, recent findings have shown that this is not always the case. Therefore, this perspective aims to provide a brief overview of the current understanding of the most widely accepted mechanisms and discuss the impact of the most recent findings.