Development of a Sealed Rechargeable Li–SO ₂ Battery

Abstract Rechargeable Li–SO ₂ batteries offer low‐cost, high‐energy density benefits and can leverage manufacturing processes for the existing primary version at a commercial scale. However, they have so far only been demonstrated in an “open‐system” with continuous gas supply, preventing practical application. Here, the utilization and reversibility of SO ₂ along with the lithium stability are addressed, all essential for long‐life, high‐energy batteries. The study discovers that high SO ₂ utilization is achievable only from SO ₂ dissolved in electrolytes between the lithium anode and carbon cathode. This results from a unique osmosis phenomenon where SO ₂ consumption increases salt concentration, driving the influx of organic solvents rather than SO ₂ from outside the current path. This insight leads to configure a bobbin‐cell with all electrolytes between the electrodes, realizing nearly 70% of SO ₂ utilization, > 12x greater than in conventional coin cells. To improve reaction rate and SO ₂ reversibility, triphenylamine is employed to the electrolyte, creating an electron‐rich environment that alleviates the disproportionation of discharge products. Incorporating this additive into a bobbin‐cell with a lithium protective layer yields a cell with a projected energy density exceeding 183.2 Wh kg ⁻¹ . The work highlights the potential of Li–SO ₂ batteries as affordable, sustainable energy storage options.