A non-aqueous Na-oxygen battery utilizes a gas mixture of CO2 and O2 as fuel. The battery exhibits a comparatively high specific energy of 6500-7000 Whkg−1 over a range of CO2 feed compositions. The energy density achieved is higher, by 200% to 300%, than obtained with pure oxygen feed. Ex-situ FTIR and XRD analysis confirm Na2O2, Na2C2O4 and Na2CO3 as discharge products. The Na—O2/CO2 battery provides a promising approach for CO2 capture and conversion into electrical energy. The Na—O2/CO2 battery may be extended to other metals. In addition, operation of a metal battery fueled at least in-part by carbon dioxide within an optimal temperature range is considered.