Physical and electrochemical contributions to the cell voltage in the thin-layer electrochemical deposition of copper at constant current

Many different processes affect the voltage across an electrochemical cell during electrochemical deposition in a thin-layer geometry. I report detailed measurements of the cell voltage as a function of time in experiments on the deposition of ramified copper aggregates from thin layers of CuSO4 electrolyte. Experiments were performed for a range of electrolyte concentrations and cell currents. The effects of various physical phenomena, including hydrodynamic convection, instability of the growing electrodeposit, and local variations in the growth rate of the aggregate are identified and studied, as are the contributions due to electrochemical phenomena.