Passivation Behavior of Aluminum in a Carbonate-Free Electrolyte Based on Lithium Bis(fluorosulfonyl)imide and Sulfolane

Carbonate-free electrolytes comprising lithium bis(fluorosulfonyl)imide (LiFSI) and sulfolane (SL) (LiFSI/SL) with medium concentrations show excellent cycle stabilities with high Coulombic efficiencies. The high Coulombic efficiencies indicate that there is no corrosion of aluminum current collectors despite the absence of LiPF6. X-ray photoelectron spectroscopy and electrochemical quartz crystal microbalance measurements show that the passivation layer on the aluminum current collector in LiFSI/SL consists of LiF and sulfurous species. The study findings will expand the applicability range of lithium-ion batteries, the current mainstay of sustainable energy sources.