We present a computational study of the interface of a Pt electrode and an aqueous electrolyte employing semi-empirical dispersion corrections and an implicit solvent model within first-principles calculations. The electrode potential is parametrized within the computational hydrogen electrode scheme. Using one explicit layer, we find that the most realistic interface configuration is a water bilayer in the H-up configuration. Furthermore, we focus on the contribution of the dispersion interaction and the presence of water on H, O, and OH adsorption energies. This study demonstrates that the implicit water scheme represents a computationally efficient method to take the presence of an aqueous electrolyte interface with a metal electrode into account.

The structure of water on metal electrodes is addressed based on first-principles calculations. Special emphasis is paid on the competition between water-metal and water-water interaction as the structure determining factors. Thus the question will be discussed whether water at metal surfaces is ice-or rather liquid-like. The proper description of liquid phases requires to perform thermal averages. This has been done by combining first-principles electronic structure calculations with molecular dynamics simulations. After reviewing recent studies about water on flat, stepped and pre-covered metal electrodes, some new results will be presented.

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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 distinct changes of the adlayer composition. Similar heating of an EC multilayer film from 80 K to room temperature results in a surface that is almost completely covered with adsorbed, carboncontaining decomposition products. This can be interpreted as the initial stage of chemical EEI formation, and the relevance of these results for battery applications is discussed.

The adsorption dynamics of water on Pt(111) was studied using ab initio molecular dynamics simulations based on density functional theory calculations including dispersion corrections. Sticking probabilities were derived as a function of initial kinetic energy and water coverage. In addition, the energy distribution upon adsorption was monitored in order to analyze the energy dissipation process. We find that on the water pre-covered surface the sticking probability is enhanced because of the attractive water-water interaction and the additional effective energy dissipation channels to the adsorbed water molecules. The water structures forming directly after the adsorption on the pre-covered surfaces do not necessarily correspond to energy minimum structures.