A rechargeable room-temperature sodium superoxide (NaO2) battery
Abstract
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-O2 cells (mostly with carbonate-based electrolytes and Li2O2 as a potential discharge product), where large overpotentials are observed and a complex cell chemistry is found. In fact, recent studies evidence that Li-O2 cells suffer from irreversible electrolyte decomposition during cycling. Here we report on a Na-O2 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 (NaO2) 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.
- Publication:
-
Nature Materials
- Pub Date:
- March 2013
- DOI:
- 10.1038/nmat3486
- Bibcode:
- 2013NatMa..12..228H