Rechargeable Room-Temperature Na-CO2 Batteries

Developing rechargeable Na-CO2 batteries is significant for energy conversion and utilization of CO2. However, the reported batteries in pure CO2 atmosphere are non-rechargeable with limited discharge capacity of 200 mAhg(-1). Herein, we realized the rechargeability of a Na-CO2 battery, with the proposed and demonstrated reversible reaction of 3CO(2) + 4Na <-> 2Na(2)CO(3) + C. The battery consists of a Na anode, an ether-based electrolyte, and a designed cathode with electrolyte-treated multi-wall carbon nanotubes, and shows reversible capacity of 60000 mAhg(-1) at 1 Ag-1 (approximate to 1000 Whkg(-1)) and runs for 200 cycles with controlled capacity of 2000 mAhg(-1) at charge voltage < 3.7 V. The porous structure, high electro-conductivity, and good wettability of electrolyte to cathode lead to reduced electrochemical polarization of the battery and further result in high performance. Our work provides an alternative approach towards clean recycling and utilization of CO2.