Role of the solid electrolyte interphase on a Li metal anode in a dimethylsulfoxide-based electrolyte for a lithium-oxygen battery

The effect of the solid electrolyte interphase (SEI) on a Li anode on the charge-discharge cycling performance in 1 M LiTFSI/dimethylsulfoxide electrolyte solution is examined by using charge-discharge cycling. The chemical structure of the surface and interior of the SEI strongly affects the cycling performance of the anode. The observed coulombic efficiency is low (<45%) when organic compounds such as lithium alkyl carbonates and polycarbonate form predominantly on the surface and interior. However, when inorganic compounds such as Li₂CO₃, Li₂O, and LiF form instead, the coulombic efficiency increases to >85%. This enhanced efficiency remains constant regardless of the O₂ content and despite <1000 ppm concentration of the contaminant H₂O in the electrolyte. Thus, the lithium surface should be protected by inorganic compounds prior to cycling to prevent it from undergoing side reactions with the electrolyte during cycling in the electrolyte.