EIS and statistical analysis of copper electrodeposition accounting for multi-component transport and reactions

Simplified models and circuit analogs are commonly used to describe electrochemical processes when applying electrochemical impedance spectroscopy (EIS). The objective of this study is to relax some of the simplifications considered in models used for EIS analysis. The proposed model accounts for species transport by diffusion, convection and migration as well as electrochemical and homogeneous reactions. The analysis is applied to the electrodeposition of copper onto a rotating disk electrode (RDE) immersed in acidic sulphate solutions. Kinetic parameters for Cu2+ reduction are obtained by fitting the model to experimental EIS and steady state current–potential data. A statistical analysis is carried out to account for correlation between successive model residuals and improve the fitting. A sensitivity analysis is also conducted to assess the impact of some of the parameters on the electrode responses. The experimental data are also found to be very poorly predicted when the parameters are used in simpler models that do not include convection and/or homogeneous reactions. Large deviations are observed in the commonly adopted approach in which convection is neglected in the transport equations and only considered to influence the boundary layer thickness.