Development of a Sealed Rechargeable Li-SO₂ Battery.

Abstract

Rechargeable Li-SO₂ 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 SO₂ along with the lithium stability are addressed, all essential for long-life, high-energy batteries. The study discovers that high SO₂ utilization is achievable only from SO₂ dissolved in electrolytes between the lithium anode and carbon cathode. This results from a unique osmosis phenomenon where SO₂ consumption increases salt concentration, driving the influx of organic solvents rather than SO₂ from outside the current path. This insight leads to configure a bobbin-cell with all electrolytes between the electrodes, realizing nearly 70% of SO₂ utilization, > 12x greater than in conventional coin cells. To improve reaction rate and SO₂ 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-SO₂ batteries as affordable, sustainable energy storage options.