Transport and Electrochemical Properties and Spectral Features of Non-Aqueous Electrolytes Containing LiFSI in Linear Carbonate Solvents

Lithium bis(fluorosulfonyl)imide (LiFSI) has been investigated as a conducting salt of liquid electrolytes for lithium-ion batteries. It shows high solubility in most polar solvents, and a concentration of is reached in dimethyl carbonate (DMC) despite its low dielectric constant. LiFSI shows a thermal stability up to on the thermogravimetric test. Compared with the /carbonate electrolytes, the LiFSI-based ones show higher ionic conductivities over a wide temperature range and higher lithium-ion transference numbers of 0.5–0.6. The conductivities of the LiFSI/DMC electrolyte over the concentration range obey a modified Casteel–Amis equation. The temperature dependence of LiFSI/DMC/EMC (3:7, v/v) is governed by the Vogel–Tammann–Fulcher relationship. The Fourier transform infrared spectra of the LiFSI/DMC electrolytes at different concentrations are systematically investigated. DMC shows significant spectral variations upon adding LiFSI, indicating strong interaction of cations with the solvent molecules. We also found that the compatibility with graphite anode and cathode in the LiFSI-based electrolyte is as good as that in the -based one, though aluminum (Al) corrosion occurs above vs . LiFSI is a very good contender to replace the latter, with increased performances and safety.