A Critical Review on Superoxide‐Based Sodium–Oxygen Batteries

Abstract Sodium superoxide (NaO 2 ) based sodium–oxygen batteries (Na‐O 2 ) possess high theoretical energy density and high energy efficiency that can be an alternative energy storage device to lithium‐ion batteries. However, the state‐of‐the‐art sodium–oxygen batteries are still far from real application due to the limited understanding of the cell chemistry and reaction mechanism. This article reviews the recent advances on NaO 2 ‐based Na‐O 2 batteries, especially focusing on the reaction mechanism and the stability of NaO 2 . The parasitic reactions from the highly active NaO 2 are discussed. It is hoped this provides insightful understanding on the mechanism and the role of the discharge product in Na‐O 2 batteries.