Lithium bis(trifluoromethanesulfonyl)imide solution

Lithium bis(trifluoromethanesulfonyl)imide in ethylene carbonate and dimethylcarbonate, 1.0 M LiTFSI in EC/DMC/EA=1:1:1 (w/w/w) is a solution of battery-grade LiTFSI dissolved in a ternary mixture of EC/DMC/EA (1:1:1) wt%. The product is a clear solution with strictly minimized impurities including low moisture (≤100 ppm), low trace metals (≤10 ppm Na and K), low chloride (<10 ppm), and low sulfate (<10 ppm).

The main application of 1.0 M LiTFSI in EC/DMC/EA=1:1:1 (w/w/w) is as an electrolyte in LIBs. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is a promising alternative to LiPF₆ since LiTFSI is more stable chemically and thermally than LiPF₆. In addition, LiTFSI is safer to handle than LiPF₆, which hydrolyzes to hydrofluoric (HF) acid. Ethylene carbonate (EC) and dimethyl carbonate (DMC) are key solvent mixtures for lithium electrolytes. DMC has a lower viscosity and melting point than EC, and when mixed with EC result in an electrolyte with a good balance between desirable electrochemical properties, high dielectric constant, and low viscosity. It is found that the addition of esters such as ethyl acetate (EA) as co-solvents can improve the conductivity of the electrolyte and the cycling performance of cells at low temperature (< 0°C). Our battery grade 1.0 M LiTFSI in EC/DMC/EA=1:1:1 (w/w/w) is particularly well-suited to experiments and applications that may operate at these low temperatures.