Mesoscale
Complexations in Lithium Electrodeposition
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Abstract
Mechanistic understanding
of lithium electrodeposition and morphology
evolution is critical for lithium metal anodes. In this study, we
deduce that Li deposition morphology evolution is determined by the
mesoscale complexations that underlie due to local electrochemical
reaction, Li surface self-diffusion, and Li-ion transport in the electrolyte.
Li-ion depletion at the reaction front for higher reaction rates primarily
accounts for dendritic growth with needlelike or fractal morphology.
Large Li self-diffusion barrier, on the other hand, may lead to the
formation of porous Li film for lower reaction rates. Enhanced ion
transport in the electrolyte contributes to homogeneous deposition,
thereby avoiding nucleation for Li dendrite formation. This study
also demonstrates that the substrate surface roughness strongly affects
dendritic growth localization over the protrusive surface features.
A nondimensional electrochemical Damkohler number is further proposed,
which correlates surface diffusion rate and reaction rate and allows
constructing a comprehensive phase map for lithium electrodeposition
morphology evolution