An Effective In situ DRIFTS Analysis of the Solid Electrolyte Interface in Lithium Ion Battery

In this work, we report a house-design spectroelectrochemical cell and the procedures for in situ diffusion reflectance Fourier transform spectroscopy (DRIFTS) analysis of the nature and formation process of the solid electrolyte interface (SEI) layer in lithium ion battery. The electrochemical performance of the designed cell is confirmed with both aqueous and non-aqueous systems and the results show its good applicability for the analysis of electrochemical reactions. While performing in situ spectroscopy analysis, a thin electrolyte layer is kept under circulation to minimize electrolyte masking effect and to maintain constant electrolyte composition. The specroelectro chemical performance of the cell was studied using 1 M LiPF6 in EC:DEC (1:1) and the DRIFTS results show the formation of (CH2OCO2Li)(2) and Li2CO3 due to EC reduction and CH3CH2OCO2Li and Li2CO3 due to DEC reduction.