A rechargeable room-temperature sodium superoxide (NaO2) battery

• Published in: Nature materials Vol. 12; no. 3; pp. 228 - 232
• Main Authors: Hartmann, Pascal, Bender, Conrad L, Vračar, Miloš, Dürr, Anna Katharina, Garsuch, Arnd, Janek, Jürgen, Adelhelm, Philipp
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.03.2013
• Subjects: Batteries; Battery; Charging; Chemical reactions; Current density; Decomposition; Discharge; Electrolytes; Electrolytic cells; Lithium; Materials science; Metals; Oxygen; Searching; Sodium
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat3486

In the search for room-temperature batteries with high energy densities, rechargeable metal-air (more precisely metal-oxygen) batteries are considered as particularly attractive owing to the simplicity of the underlying cell reaction at first glance. Atmospheric oxygen is used to form oxides during discharging, which-ideally-decompose reversibly during charging. Much work has been focused on aprotic Li-O(2) cells (mostly with carbonate-based electrolytes and Li(2)O(2) as a potential discharge product), where large overpotentials are observed and a complex cell chemistry is found. In fact, recent studies evidence that Li-O(2) cells suffer from irreversible electrolyte decomposition during cycling. Here we report on a Na-O(2) cell reversibly discharging/charging at very low overpotentials (< 200 mV) and current densities as high as 0.2 mA cm(-2) using a pure carbon cathode without an added catalyst. Crystalline sodium superoxide (NaO(2)) forms in a one-electron transfer step as a solid discharge product. This work demonstrates that substitution of lithium by sodium may offer an unexpected route towards rechargeable metal-air batteries.