XPS and SEM-EDX Study of Electrolyte Nature Effect on Li Electrode in Lithium Metal Batteries

Understanding the solid electrolyte interphase (SEI) in lithium batteries is very important to face the major safety issue of lithium dendritic growth during battery charge. The aim of this work is to study the thickness and the chemical nature of the SEI by XPS, as well as their influence on the electrochemical performance of the battery for different liquid organic electrolytes. XPS imaging is also used in this work to get a chemical mapping of the SEI layer components formed on the metallic lithium electrode surface cycled in different conditions. Data processing based on the principal component analysis (PCA) method has been conducted in order to illustrate the SEI layer heterogeneities. The obtained results are compared with energy-dispersive X-ray spectroscopy (EDX) mapping. Thereby, the benefits and the precision of the XPS imaging technique to identify chemical compounds distribution have been highlighted. These different analyses have led to a better knowledge of the redox processes occurring at the top surface of lithium metal electrodes cycled in different liquid electrolytes.