Morphological phases and exhaustion-induced Hecker effect in electrodeposition

We report a pattern formation study of zinc electrodeposition in galvanostatic conditions. The microscopic structure is based on two alternative growth mechanisms: dendritic (generic) or tip splitting (disturbed) and is decoupled from the macroscopic structure. We present the corresponding phase diagram, demonstrate the limits of the experimental range, and show that the microscopic selection is dominated by the initial concentration of zinc. The macrostructure consists of stable front and dense branches or unstable front and sparse branches. The dense phase is always followed by the Hecker transition. We show that the transition point coincides with the exhaustion of ions from the solution. Hence, the time to the transition is also determined by the concentration