DMSO–Li2O2 Interface in the Rechargeable Li–O2 Battery Cathode: Theoretical and Experimental Perspectives on Stability

One of the greatest obstacles for the realization of the nonaqueous Li–O₂ battery is finding a solvent that is chemically and electrochemically stable under cell operating conditions. Dimethyl sulfoxide (DMSO) is an attractive candidate for rechargeable Li–O₂ battery studies; however, there is still significant controversy regarding its stability on the Li–O₂ cathode surface. We performed multiple experiments (in situ XPS, FTIR, Raman, and XRD) which assess the stability of the DMSO–Li₂O₂ interface and report perspectives on previously published studies. Our electrochemical experiments show long-term stable cycling of a DMSO-based operating Li–O₂ cell with a platinum@carbon nanotube core–shell cathode fabricated via atomic layer deposition, specifically with >45 cycles of 40 h of discharge per cycle. This work is complemented by density functional theory calculations of DMSO degradation pathways on Li₂O₂. Both experimental and theoretical evidence strongly suggests that DMSO is chemically and electrochemically stable on the surface of Li₂O₂ under the reported operating conditions.