Structure Formation and Thermal Stability of Mono- and Multilayers of Ethylene Carbonate on Cu(111): A Model Study of the Electrode|Electrolyte Interface

Abstract

In this work, we aim at a molecular scale understanding of the interactions and structure formation at the electrode|electrolyte interface (EEI) in Li-ion batteries. Therefore, the interaction of the key electrolyte component ethylene carbonate (EC) with Cu(111) was investigated under ultrahigh vacuum conditions. Scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIRS), and dispersion-corrected density functional theory (DFT-D) calculations were employed. After vapor deposition of EC (sub-) monolayers on Cu(111) at 80 K, STM measurements (100 K) reveal a well-ordered commensurate superstructure, in which EC molecules assume different configurations and whose total adsorption energy is mainly governed by van der Waals interactions, as demonstrated by DFT-D. In the temperature range between 150–220 K, competing desorption and decomposition into −C═O, −C–O–C–, −C–H, and −C–C– compounds, as derived by XPS and confirmed by FTIRS, result in dis...