Sodium–air batteries were proposed with the hopes of overcoming the battery instability associated with superoxide in lithium–air batteries.
Sodium, with an energy density of 1605 Wh/kg, does not boast as high an energy density as lithium. However, it can form a stable superoxide (NaO2) as opposed to the superoxide undergoing detrimental secondary reactions. Since NaO2 will decompose reversibly to an extent back to the elemental components, this means sodium–air batteries have some intrinsic capacity to be rechargeable.
Sodium–air batteries can only function with aprotic, anhydrous electrolytes. When a DMSO electrolyte was stabilized with sodium trifluoromethanesulfonimide, the highest cycling stability of a sodium–air battery was obtained (150 cycles)