Fourier-transform infrared spectroscopic studies on the solid electrolyte interphase formed on Li-doped spinel Li_1.05Mn_1.96O₄ cathode

Fourier-transform infrared (FTIR) spectroscopy has been used to identify the solid electrolyte interphase (SEI) formed on Li-doped spinel Li_1.05Mn_1.96O₄ cathode. The major components in the SEI have been assigned, and the formation and evolution of the SEI over the initial charge-discharge cycle are discussed. By Fourier-transform infrared spectroscopy, it has been found that during the charge-discharge process, the SEI can be directly formed on the Li_1.05Mn_1.96O₄ cathode, and is mainly composed of R-CO₃Li and Li₂CO₃. In terms of composition, it is very similar to those formed on a carbon anode. In the initial cycle, the formation of R-CO₃Li begins at 4.10 V during the charging process, and becomes more distinct with increasing charge voltage. The formation of Li₂CO₃ begins at 4.10 V during the discharge process, and becomes more distinct with decreasing discharge voltage. The SEI becomes more evident over subsequent cycles.