Sodium–oxygen batteries: a new class of metal–air batteries

Research on sodium–oxygen batteries has gained unprecedented momentum in recent times. With a high theoretical specific energy of 1600 W h kg−1 and an equilibrium discharge potential of 2.3 V, a rechargeable sodium–oxygen battery embodies an attractive new metal–air battery platform for applications in transportation. As an earth-abundant element, sodium has the potential to be a low cost replacement for lithium in electrochemical storage technologies while retaining the majority of its qualities. This highlight focuses on the development and current progress in the field of sodium–oxygen batteries. Strategies for improving the reversibility of the electrode reactions and for understanding and overcoming key problems in sodium–oxygen batteries are also discussed.