The Sodium-Oxygen/Carbon Dioxide Electrochemical Cell

Electrochemical cells that utilize metals in the anode and an ambient gas as the active material in the cathode blur the lines between fuel cells and batteries. Such cells are under active consideration worldwide because they are considered among the most promising energy storage platforms for electrified transportation. Li-air batteries are among the most actively investigated cells in this class, but long-term challenges, such as CO2 contamination of the cathode gas and electrolyte decomposition, are associated with loss of rechargeability owing to metal carbonate formation in the cathode. Remediation of the first of these problems adds significant infrastructure burdens to the Li-air cell that bring into question its commercial viability. Several recent studies offer contradictory evidence, namely, that the presence of substantial fractions of CO2 in the cathode gas stream can have significant benefits, including increasing the already high specific energy of a Li-O-2 cell by as much as 200%. In this report, we consider electrochemical processes in model Na-O-2/CO2 cells and find that, provided the electrode/electrolyte interfaces are electrochemically stable, such cells are able to deliver both exceptional energy storage capacity and stable long-term charge-discharge cycling behaviors at room temperature.