Phase field modeling of dendrite growth mechanism of Mg and Li in electrodeposition

Dendrite growth causing short circuits is a long-standing challenge in the battery field. Lithium-ion batteries are always prone to form dendrite, while magnesium-ion batteries are not. In this paper, an advanced phase field model is formulated to investigate the detailed patterns and growth differences between the lithium and magnesium deposition process. The simulation results show that the deposition growth of ion is relative to the deposition time. Furthermore, the deposition growth morphology of Li is the irregular tree-like pattern, while the deposition pattern of Mg is denser and smoother. According to our phase field model results, the contribution of a smaller electric field and driving force are important factors to make Mg form a dense deposition layer rather than a tree-like dendritic morphology, which Li prefers to form. For the dendrite growth of Li, a larger electric field and driving force at the dendrite tip lead to a stronger concentration of ion and more rapid dendrite growth. And the "entrainment" phenomenon of ion leading to positive feedback further accelerates the deposition of Li ion at the dendrite tip. Furthermore, the simulation results exhibit that the overpotential required to stimulate the rapid growth of magnesium dendrites is typically smaller than that of lithium.