Understanding Morphology Evolution in Lithium Electrodeposition

Abstract

Lithium-ion batteries are poised to play an important role in the push for electric vehicles. Electroplating and possible dendritic growth, however, have been a safety concern. Non-uniform electrodeposition and subsequent growth may cause short circuit. Apart from catastrophic failure, Li plating results in the battery performance decay as well. There is a need for a better understanding of the factors that are most critical in the nucleation and growth of Li electrodeposition and the morphology evolution thereof. The metal ion reaches the electrode surface where it is reduced. The metal atom can thereafter diffuse inside the bulk electrode or aggregate on the surface under some specific set of conditions and form a variety of structures on the electrode surface, like small islands, uniform film, mossy or filament like structure or dendrite (as schematically shown in Figure 1). Physicochemical determinants affecting electrodeposition include the adsorption energy of metal atom on electrode surface, diffusion barrier for metal atom in the bulk electrode compared to that on the electrode surface, the crystallographic nature of the electrode surface, the strength of cohesive metal-metal interaction. Beyond the nature of the electrode material, the operating temperature, current density and applied potential can also affect the electrodeposition rate, which consequently control the morphology evolution. In this study, a mesoscale interfacial modeling and analysis is presented in order to investigate the lithium electrodeposition regimes and morphology evolution. Figure 1