The core technology of Elsyca is based upon the idea to consider an electrochemical system as a closed system of electric sources, connections, electrodes, electrode reactions and electrolyte solutions. An example is shown in the figure: The current distribution in both electrochemical cells (tanks filled with an electrically conductive, water based electrolyte) is determined not only by what happens in the tank, but also by the connections to the sources, the internal electrical resistance of the coil to be surface treated (e.g. steel or aluminium) and the possible leackage or stray currents to earth.

An electrochemist will mainly focus on electrode reactions and electrolytical solutions in a simple and well defined geometry (e.g. a lab setup with rotating disc electrode). Elsyca engineers incorporate the same electrolyte bath characteristics in their models but focus also on the electrotechnical, thermal and mechanical aspects of the process at the same time: voltage drops in wires and electrodes, current density distributions, layer thickness distributions, growth or dissolution of electrodes, heat removal and mass transport. This theoretical-scientific approach provides the real industrial added-value, because it permits to simulate parameter variations (e.g. electric currents, cell geometry, electric circuitry, etc.) thus enabling to work at maximum effectiveness.

Within the global modeling and engineering of an electrochemical system, one can distinguish the different phenomena as discussed below:

Sources and connectionsFor DC current phenomena, sources and connectors between sources and electrodes can be described mathematically as an electrical network, eventually with time dependent current- and voltage sources, resistances and sometimes also diodes. Solving this network results in time dependent potentials V in de nodes of the network and in connectors with the electrodes, and time dependent currents I in de branches of the network.

A similar approach is possible when an alternating current or voltage sources is applied. Real time or RMS calculations can be performed, even when three phase systems are applied to electrochemical cells.

Electrodes

Electrodes can be considered as currents collectors respectively current distributors between connectors and the electrolyte. Whenever electrodes move in the electrochemical cell, grow strongly (electroforming) or dissolve significantly (electrochemical machining ECM, polishing or etching) due to an electrochemical treatment, these movements are taken into account.

Electrodes also play a major role in the heat generation and distribution towards the electrolyte bath and along the surface of the electrodes.

To conclude: local voltage distributions and/or temperature distributions and/or electrode movements are phenomena which can and should be taken into account for modeling and engineering of an electrochemical system.

Electrode reactions

The electrochemical surface reactions can be quite complex. They depend upon adsorption, acid-base equilibria, complexation reactions, etc. Different reactions can also occur at the same time: gas evolution as a side reaction, co-deposition of different metals to result in an alloy deposition.

For the potential model (see below) a global link between the current density and overvoltage J=f (V-U) is required. Combining this model to the multi-ion model, a complete reaction mechanism can be determined, providing even more info as for example reaction current densities, exhaustion of reagentia near the electrode surface, etc. These reactions involve strongly non-linear boundary conditions between electrodes and the electrolyte solution.

Electrolyte solution

The electrolyte solution contains solvent (in most cases water), ions en non-charged particles. For some electrochemical systems the potential model, which only takes into account the conductivity of the electrolyte, describes very accurately the electrochemical reality. It results in potential- and current distributions in the solution and near the electrodes.

The multi-ion model takes into account the mass transport of all particles under the influence of convection, diffusion, migration and if required also homogeneous reactions. Solving this model in combination to the electroneutrality condition results in potential- and concentration distributions of all relevant particles in the solution. From these variable fields one can derive the local current density and mass transfer limitations.

The multi-ion model requires thus that the electrolyte fluid flow vector field is available. This can be derived from solving the Navier-Stokes equation. Elsyca has all core technology in house to calculate flow fields in laminar and turbulent flow conditions.