Browsing by Author "Cheung, Benji H"

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    A kinetic Monte Carlo simulation of solid-electrolyte interphase formation and dendrite growth during electroplating
    (2024-12-05) Cheung, Benji H; Tang, Ming
    The formation of 3D structures such as dendrite, filament, and moss during electroplating is an obstacle to the development of a number of battery systems vital to a sustainable future, particularly lithium metal batteries. The morphological evolution of lithium metal electrode is strongly affected by the presence of passivating species formed by electrolyte decomposition, known as solid-electrolyte interphase (SEI). A 2D kinetic Monte Carlo (kMC) algorithm on a hexagonal grid was developed to account for the competing effects of deposition, diffusion, and surface passivation, providing an elementary understanding of electrodeposition systems with passivation. Growth from flat electrode and from hemispherical nucleus were both investigated. Morphological information and shape statistics were found to be strongly controlled by both SEI initiation time and current density, and a phase map was constructed over both parameters to demonstrate the distribution of results. Spherical deposits formed at high passivation time and high flux, filaments and whiskers at low flux and high passivation time, and dendrites and mosses at high flux and low passivation time. SEI formation is also observed to exacerbate nascent diffusion instabilities on pristine electrode. In the limit of no cross-SEI diffusion, we obtain a scaling relation of filament lengthscale as flux^(0.35) t_pass^(2.17). When cross-SEI diffusion was considered, a contrast is observed between low and high flux regimes: traditionally, thickness decreases with current, but at high fluxes after SEI cracking, we observe that growth from a single active tip can sustain larger thicknesses with larger flux, shedding light on an SEI-free ultrahigh flux regime. These findings provide foundational yet novel understanding of complex SEI phenomena, potentially streamlining the design of next-generation batteries.