Simulating solid electrolyte interphase formation spanning 10⁸ time scales with an atomically informed phase-field model

The solid electrolyte interphase (SEI) governs the reversibility of advanced electrochemical devices such as batteries, but the role of cations in its formation remains poorly understood. Here, the thickness and compositional evolution of the SEI are tracked over time scales from nanoseconds to seconds with a newly developed atomically informed phase-field multiscale model. We deconvolve the complex interplay among electron tunneling, species diffusion, and chemical/electrochemical reactions by probing different controlling factors separately and jointly to determine the rate-limiting steps. We show that the SEI growth begins with the formation of organic products, followed by the conversion of these organic products into inorganic ones, and in the end the inorganic products fully cover the lithium metal surface to form a passivation layer. While electron tunneling determines the thickness of these layers, the growth rates of the organic and inorganic SEI layers are controlled by the rates of Li-ion diffusion and electrochemical reactions, respectively. This predictive model is universally applicable to multiphase and multicomponent electrochemical systems and represents a significant advancement in simulating complex reaction processes.