Modelling the dynamic growth of copper and zinc dendritic deposits under the galvanostatic electrolysis conditions

• Spherical diffusion determines zinc and copper dendrite growth at high polarisation.
• Equations which describe growth and differentiation of current efficiency of zinc and copper dendrites.
• Presentation of dendrites as a hypothetical thread to aid calculation of tip density.
• Dendrite branch fusion leads to shell formation.
• A model of zinc and copper dendrite electrodeposition, based on empirical parameters.

This paper investigates the process of crystallisation of the copper and zinc dendritic deposits under galvanostatic conditions on the rod electrode. The effect of the value of current and metal ion concentration in solutions on the growth dynamics of loose deposits is studied. It is shown that the current efficiency of the metal increases, and the growth rate decreases during the elongation of dendritic particles, and an increase in the surface area on which the electrocrystallisation takes place. Empirical equations for the quantitative description of changes in time of the lengths of the dendrites and the current efficiency of copper and zinc are proposed, which well approximate the experimental data obtained under various conditions of electrolysis.A phenomenological model is worked out that helps to calculate the variation of structural parameters in time (the number and the radius of tips of the dendrite branches) of the loose deposit growth and to determine the moment of transition from a loose deposit to a compact one.