Formation of Solid Electrolyte Interphase from the Decomposition of Ethylene Carbonate on Aluminum-Doped Silicon - A DFT Analysis

Lithium-ion batteries have become indispensable in modern energy storage, with applications ranging from portable electronics to electric vehicles. Enhancing their performance is a critical area of research. In this study, the impact of surface aluminum doping in silicon electrodes on the formation of the solid electrolyte interphase (SEI) during the early stages of battery cycling is investigated. The reduction mechanism of ethylene carbonate, a key SEI precursor, is studied using density functional theory calculations including the influence of potential and modeling the solvent as a continuum. Energy diagrams, both with and without hybrid solvation effects, indicate that the presence of aluminum promotes thermodynamically favorable SEI formation and adsorption on silicon surfaces. Moreover, the presence of aluminum maintains the favorable kinetic characteristics observed in the undoped system. These effects could have important consequences in reducing unstable SEI growth by volumetric expansion during lithiation-delithiation cycles, potentially improving battery performance.