Carbon dioxide assist for non-aqueous sodium–oxygen batteries

We report a novel non-aqueous Na–air battery that utilizes a gas mixture of CO2 and O2. The battery exhibits a high specific energy of 6500–7000 Whkg− 1 (based on the carbon mass) over a range of CO2 feed compositions. The energy density achieved is higher, by 200% to 300%, than that obtained in pure oxygen. Ex-situ FTIR and XRD analysis reveal that Na2O2, Na2C2O4 and Na2CO3 are the principal discharge products. The Na–CO2/O2 and Mg–CO2/O2 battery platforms provide a promising, new approach for CO2 capture and generation of electrical energy.

► We report a novel sodium–CO2/O2 battery that uses a mixture of CO2 and O2 as fuel.
► Na–CO2/O2 batteries provide a platform for CO2 capture and conversion.
► Moderate levels of CO2 in an O2 feed produce up to 300% enhancement in performance.
► Postmortem studies reveal carbonates and oxalates are dominant discharge products.
► A mechanism is proposed for the electrochemical reactions in Na–CO2/O2 batteries.