Revealing Excited-State Electrochemical Reaction Pathways at Solid Electrolyte Interphases by Ab Initio Nonadiabatic Molecular Dynamics

Abstract

Electrode potential controls electrochemical reactivity by governing interfacial electron-transfer processes at electrified interfaces. Under varying electrochemical potentials, injected electrons may access different electronic states of interfacial electrolyte complexes, potentially driving distinct nonequilibrium excited-state reaction pathways. Conventional electrochemical frameworks primarily focus on equilibrium reaction energetics, while the nonequilibrium dynamics following interfacial electron transfer remain largely unexplored. Here, we investigate such ultrafast interfacial reaction dynamics using ab initio nonadiabatic molecular dynamics (NAMD) simulations within the Ehrenfest dynamics framework. Using ethylene carbonate (EC) as a prototypical electrolyte solvent in Li-ion batteries, we show that electron injection into different electronic states of solvated Li+ complexes can drive qualitatively distinct nonadiabatic reaction pathways on femtosecond-to-picosecond time scales. Furthermore, local solvation environments and interactions between neighboring reaction units substantially modify the reaction landscape and the resulting decomposition channels relevant to solid electrolyte interphase formation. This work establishes a microscopic nonequilibrium perspective on electrochemical reactivity and suggests that excited-state dynamics may play an important role in interfacial electrochemical reactions beyond conventional ground-state descriptions.