Ion transport and deposit growth in spatially coupled bipolar electrochemistry

In spatially coupled bipolar electrochemistry, electrodissolution and electrodeposition processes in an applied electric field are exploited to create directional growth of copper deposits between two copper discs, not physically linked to an external voltage source. Here, we study the electric field in the whole cell through theoretical modeling, and ion transport in the interdisc region using optical and particle image velocimetry techniques. Their combined effect on incubation time and deposit morphology is assessed. Both the electric field and ion transport in the interdisc region are crucial factors in the characteristics of the Interconnection. The model simulations reveal that the electric field is almost an order of magnitude larger in the region between discs as compared with the mean field value. Measurements and simulations show that the incubation time scales linearly with the inverse of the electric field, an indication that in this period, migration is the dominant transport mode. Experiments reveal that after branching develops. convection plays a relevant role as well, the contact growing linearly in time, with a change of the time length slope at half the interdisc gap. (C) 1999 Elsevier Science S.A. All rights reserved.