A study on the electrochemical kinetics for the prediction of composition and thickness of Zn-Ni plating

Abstract This study evaluates electrochemical kinetic parameters for a Zn–Ni electroplating process by combining finite element modeling with experimental validation. A finite element model based on the Laplace equation and Butler–Volmer boundary conditions was created to predict deposition thickness, current efficiency, and alloy composition for electrodeposition using a commercial electrolyte. Kinetic parameters for oxygen evolution at the anode and Zn, Ni, and hydrogen reduction at the cathode were determined experimentally from controlled mass transfer of a rotating disc electrode and extracted via Koutecký–Levich plots. The exchange current density of Zn and Ni deposition were found to be 53.0 and 2.99 mA cm-2, respectively. Model predictions were validated at varying interelectrode gaps (and therefore ohmic loss in the electrolyte) by comparing simulated results to measured plating thickness, alloy composition, and current efficiency of a physical setup. Parametric sweeps of the kinetic parameters were then performed to assess their influence on model outputs. The final model computations for plating thickness and composition were on average within 9.9% and 6.8% of their respective experimental results. Prediction of plating thickness, composition, and current efficiency all have operational utility in electroplating processes, and the model is suggested for use over resource-intensive experimental work.