Role of Anion Flexibility on Graphite Electrode Reactions in Bis(fluorosulfonyl)amide-Based Ionic Liquid Electrolytes for Lithium-Ion Batteries

We subjected bis­(fluorosulfonyl)­amide (FSA)-based ionic liquid (IL) electrolytes for lithium (Li)-ion batteries to structural and electrochemical studies to elucidate the criticality of “FSA-anion flexibility” on Li-ion solvation/desolvation and electrode-reaction properties in the batteries. Raman spectroscopy, high-energy X-ray total scattering, and theoretical calculations were used to comprehensively conduct the structural investigation to reveal the occurrence of specific Li-ion solvation in the LiFSA/IL solutions exhibiting low and extremely high LiFSA concentrations (c Li). Li ions in the low-c Li solutions (