Growth and dissolution of NaO 2 in an ether-based electrolyte as the discharge product in the Na-O 2 cell.

The deposition and dissolution of sodium superoxide (NaO2 ) was investigated by atomic force microscopy. Rectangular prisms consisting of 8 smaller sub-structures grew from NaO2 platelets, when discharged in 0.5 M NaClO4 , diethylene glycol dimethyl ether on highly ordered pyrolytic graphite. During oxidation the 8 sub-structures are conserved. Ring-like structures of Na2 CO3 of 200 nm diameter remain at the end of oxidation.