Understanding and suppressing side reactions in Li–air batteries

Abstract

Li–air batteries have attracted intensive recent research attention owing to their extremely high energy density that is ten times that of the conventional Li-ion batteries; however, achieving this energy capability in practical Li–air batteries has been proven to be difficult. A lot of effort has been devoted to improving their stability, energy efficiency and cycle life with a better understanding of the reaction mechanisms. The electrochemical processes associated with the reversible formation/decomposition of Li₂O₂ are affected by the surrounding conditions, which often involve several side reactions. In this review, we summarize recent progress in Li–air batteries, especially in the side reactions taking place in the electrochemical process, including carbon corrosion in the cathodes, electrolyte degradation, and the shuttle effect of redox mediators in the electrolytes as well as contaminants from the air (CO₂, H₂O, and N₂). The main strategies for suppressing or making full use of these side reactions for enhancing the performance of Li–air batteries are presented. Meanwhile, we also provide perspectives on the development of Li–air batteries.