Spatially Resolved Growth Mechanisms of a Lithium Dendrite Population

Abstract

By developing a thermodynamically consistent phase field framework, which includes position-dependent large deformation mechanics, plasticity, electrochemistry, and electrodeposition, twelve growth mechanisms were identified. Specifically, previously reported tip-controlled growth mechanism is resolved in to (a) flat tops, (b) rounded tops, (c) edge shielding, (d) electrical shielding, and (e) local electrochemical exchange. Similarly, previously reported base-controlled growth mechanism is resolved in to: (f) initial base controlled growth, (g) late base controlled growth, (h) merged bases, and (i) unmerged bases. Finally, previously reported mixed growth mechanism is resolved in to: (j) local mechanical equilibrium, (k) dendrite bending, and (l) stressed junctions. Longer dendrites predominantly grow through electrodeposition while shorter dendrites predominantly grow through plastic flow. Further, local electrochemical and mechanical dendrite branch interactions induce lateral dissolution and deposition that lead to microstructural changes in the dendrite morphology.