Room-temperature rechargeable Na–SO2 batteries containing a gel-polymer electrolyte

Abstract

We constructed rechargeable Na–SO₂ batteries, based on a NaI redox mediator and containing a gel-polymer electrolyte and a multiwall carbon nanotube@Ni foam porous cathode, with a newly demonstrated battery reaction, specifically 2Na + 2SO₂ ↔ Na₂S₂O₄. A large reversible capacity of 5000 mA h g⁻¹ at 200 mA g⁻¹ (763 W h kg⁻¹) and a high capacity retention of nearly 100% after 100 cycles were obtained.