Rechargeable Room‐Temperature Na–CO₂ Batteries

Developing rechargeable Na–CO 2 batteries is significant for energy conversion and utilization of CO 2 . However, the reported batteries in pure CO 2 atmosphere are non‐rechargeable with limited discharge capacity of 200 mAh g −1 . Herein, we realized the rechargeability of a Na–CO 2 battery, with the proposed and demonstrated reversible reaction of 3 CO 2 +4 Na↔2 Na 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 mAh g −1 at 1 A g −1 (≈1000 Wh kg −1 ) and runs for 200 cycles with controlled capacity of 2000 mAh g −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 CO 2 .