Shedding new light on conventional primary batteries sometimes inspires new chemistry adoptable for rechargeable batteries. Recently, a primary lithium-sulfur dioxide battery, which offers a high energy density and a long shelf-life, was successfully renewed as a promising rechargeable system exhibiting significant merits over the lithium-oxygen chemistry such as small polarization and good reversibility.¹ Here, we demonstrate, for the first time, that the reversible operation of the lithium-sulfur dioxide battery is also possible exploiting conventional carbonate-based electrolytes. Even though carbonate-based electrolytes possess advantages such as high ionic conductivity and good electro/chemical stability and have thus been widely used in commercial lithium-ion batteries, they have not been used in metal–air batteries because of the occurrence of serious side reactions. The attempt to use carbonate-based electrolytes during the early development of rechargeable lithium–oxygen and sodium–oxygen batteries failed, yielding significant side reaction products; thus, appropriate charging process could not be achieved.^2,3 The organic carbonate was highly vulnerable to chemical attacks by gas radicals generated during the discharge process. This finding has led to the general perception that carbonate-based electrolytes cannot be considered for metal–gas batteries. However, theoretical and experimental studies reveal that the SO₂ electrochemistry is highly stable in the carbonate-based electrolytes enabling the reversible formation of Li₂S₂O₄ in contrast to lithium-oxygen batteries. The use of the carbonate-based electrolyte leads to the remarkable enhancement of power and reversibility with much improved compatibility with lithium metal; furthermore, the optimized lithium-sulfur dioxide battery with catalysts achieves the outstanding cycle stability over 450 times with 0.2 V polarization, which is one of the highest efficiencies reported for metal-gas batteries. This study highlights the potential promise of rechargeable lithium-sulfur dioxide chemistry along with the viability of the conventional carbonate-based electrolytes in metal-gas rechargeable systems. We expect this finding to open up a further opportunity for the lithium–sulfur dioxide chemistry as a promising next-generation rechargeable battery and spur vigorous discussions on the role of the electrolyte in metal–air batteries.

Reference

1. Lim. H. -D. et al. Ange. Chem. 127, 9799 (2015).
2. Freunberger, S. A. et al. J. Am. Chem. Soc. 133, 8040 (2012).
3. Kim. J. et al. Phys. Chem. Phys. Chem. 15, 3623 (2013).