In-operando FTIR Spectroscopy for Composite Electrodes of Lithium-ion Batteries

Electrolyte decomposition processes on cathode and anode active materials significantly affect to the cycle life and the calendar life of lithium-ion batteries. Here we designed a new in-operando FTIR spectroscopy cell to investigate the decomposition process of the electrolyte solutions. The cell is compatible with various cathodes and anodes for lithium-ion batteries and the charging-discharging rate can be increased up to 1 C. In the case of the conventional cathode active material LiMn2O4, the in-operando spectra shows adsorption and solvation process of the electrolyte solvent molecules, while no clear evidence of the electrolyte oxidation process is observed. On the other hand, the solid electrolyte interphase (SEI) layer formation processes on graphite anodes are clearly observed. Hence, we think the new measurement technique should be a powerful tool for the development of electrolyte additives.