Characterization of Solid Electrolyte Interphase on Some Electrodes in the Bis(fluorosulfonyl)Amide Anion-Based Ionic Liquids with Different Li Salt Concentrations

摘要

Aprotic ionic liquids are investigated as the next generation electrolytes for lithium ion battery (LIB) because non-flammability of ionic liquids is expected to improve the safety of the LIB. Bis(fluorosulfonyl)amide (FSA) anion-based ionic liquids have been attracting attention because of the formation of stable solid-electrolyte interphase (SEI) on the electrode surface during charge-discharge reactions. The SEI is known to form as a result of reductive decomposition of electrolytes and considered as a lithium ion conductor, though its nature like composition has not been clarified yet especially in ionic liquid electrolytes. In the present study, the SEIs on some different electrodes in 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)amide (MPPFSA) containing LiFSA at different concentrations were characterized by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS).