Dense branched morphology in electrochemical deposition in a thin cell vertically oriented

G. GONZÁLEZ , A. SOBA , G. MARSHALL , F. V. MOLINA AND M. ROSSO.

ELECTROCHIMICA ACTA

ELSEVIER SCIENCE

Año: 2007 vol. 53 p. 133 - 140

0013-4686

Trabajo completo del 4th Int. Symp. Electrochemical Processing of Tailored Materials, 3-5 Oct. 2005, Kyoto University, Japan (a aparecer en Electrochimica Acta bajo procesos habituales de referato de dicha publicación ). Abstract  Convection due to electric and gravity forces increase complexity in thin layer electrochemistry (ECD). To reduce convection we describe conditions in a vertical cell with the cathode above the anode in which global convection is eliminated and  a dense branched morphology with a smooth front is obtained. It is shown that these conditions allow a theoretical one dimensional modeling notably simplifying the complex analysis of the problem. Accordingly, we report ECD experimental measurements in a vertical cell under constant current conditions, we discuss  a macroscopic model of ECD  with a three ion electrolyte in conditions of dense branched morphology and we present   numerical simulations predicting many features of those experiments.  The model describes ion transport and deposit growth through the one-dimensional Nernst-Planck equations for ion transport, the Poisson equation for the electric field and a growth law for deposit evolution under galvanostatic conditions. The model predicts cation, anion and proton concentration profiles, electric field variations and deposit growth speed, that are in excellent agreement with experiments; the predicted evolution and collision of the deposit and proton fronts reveal a time scaling close to those observed in experiments.