In situ concentration measurements around the transition between two dendritic growth regimes

A transition between two different dendritic growth regimes in the electrodeposition of a metal from a binary electrolyte was studied using two different optical techniques. These regimes are observed respectively at current densities below and above the limiting diffusion current density. In situ concentration measurements around the transition were performed by laser interferometry and optical absorption due to Cu2+ ion. These measurements reveal that concentration profiles and their time evolution are different in the two growth regimes: before the transition, corresponding to the high current density regime, concentration gradients are uniform throughout the cell, and the concentration increases with time at the anode. After the transition to low current density regime, the concentration gradient in front of the most prominent dendrite increases markedly, while the concentration becomes almost constant at the anode. At the transition, the time evolution of the cell potential slows down significantly.

► Electrodeposition of Cu from CuSO4. ► Transition between two dendritic growth regimes. ► Concentration measurements by optical techniques.