Insights into solid electrolyte interphase formation on alternative anode materials in lithium-ion batteries

To gain new insights into the formation of the solid electrolyte interphase (SEI), as a basis for the safe and efficient use of new anode materials, we studied SEI formation on silicon and lithium titanate (LTO) anodes by electrochemical impedance spectroscopy (EIS) and ex situ X-ray photoelectron spectroscopy (XPS) measurements. While EIS measurements performed at equidistant voltage intervals provided insights into the SEI formation process, ex situ X-ray photoelectron spectroscopy (XPS) measurements supplied data on the chemical composition of the SEI layer. On silicon anodes we observed that resistance decreases in the second cycle which suggests the formation of a stable SEI with SiO2, Li4SiO4, LiF and different carbonates as its main components. On LTO anodes, however, resistance increases by a factor of two indicating incomplete SEI formation. Here LiF and different carbonates were identified as the SEI’s main components