Investigations on the electrochemical performance and thermal stability of two new lithium electrolyte salts in comparison to LiPF6

Electrolyte solutions, containing the lithium salts lithium-cyclo-difluoromethane-1,1-bis(sulfonyl)imide (abbreviated as LiDMSI) and lithium-cyclo-hexafluoropropane-1,1-bis(sulfonyl)imide (LiHPSI) dissolved in organic carbonate solvents, were electrochemically investigated on graphite and LiNi1/3Mn1/3Co1/3O2 (NMC) electrodes and compared to the electrolyte salt LiPF6 with regard to conductivity, the electrochemical stability window, the anodic dissolution behavior vs. aluminum as well as the thermal stability behavior at 60°C. XPS studies were carried out to investigate the influence of the salt on the composition and the thickness of the solid electrolyte interphase (SEI). Constant current cycling experiments proved the potential applicability of the investigated salts for lithium ion batteries.