Rechargeable Na–SO₂ Battery with Ethylenediamine Additive in Ether‐Based Electrolyte

Rechargeable metal–SO 2 batteries have drawn tremendous attention because it can accelerate SO 2 fixation/utilization and offer high energy density. Herein, a rechargeable Na–SO 2 battery based on an ether‐based liquid electrolyte with an ethylenediamine (EDA) additive is realized via the reversible formation/decomposition of Na 2 S 2 O 4 . Experimental investigations reveal that the EDA additive provides three benefits by simultaneously decreasing the overall electrode polarization, increasing the full discharge capacity, and improving battery cyclability. At a current density of 250 mA g −1 , the full discharge capacity of the battery with the EDA additive is more than twice of a similar system in the absence of EDA. In addition to the significantly enhanced capacity, the as‐assembled Na–SO 2 battery demonstrates excellent cyclic stability after 200 cycles, which is equivalent to a total duration of 1600 h. Moreover, the corrosion resistance of Na anode is strengthened with the aid of EDA in the SO 2 ‐containing liquid electrolyte. This work will pave the way for Na–SO 2 batteries as a promising battery technology toward both pollutant gas utilization and energy storage.