Secondary Current Distribution
Now start setting up the current distribution model, beginning with the settings for the electrolyte.
Define the Electrolyte Node
1
In the Model Builder locate the Secondary Current Distribution node and then click Electrolyte 1 .
 
 
The ‘D’ in the upper left corner of a node means it is a default node.
2
In the Settings window under Electrolyte, from the Electrolyte conductivity σl list, select User defined. Enter kappa in the text field.
Define the Electrode Surface and the Electrode Reaction Node
Now define the cathode and the cathode electrode reaction. The combination of properties for the surface and the reaction stoichiometry will determine how the magnitude and direction of the growth velocity of the deposited layer relate to the electrode reaction currents.
1
In the Physics toolbar click Boundaries and choose Electrode Surface .
2
In the Model Builder, under Secondary Current Distribution, click Electrode Surface 1 .
3
Click the Paste Selection button and enter 4.
4
In the Settings window for Electrode Surface, click to expand the Dissolving-Depositing Species section.
5
Click Add. In the table, type in Ni, rho_Ni, and M_Ni in the Species, Density, and Molar mass columns, respectively. Select Solve for surface concentration variables.
6
Expand the Electrode Surface 1 node and click the Electrode Reaction 1 .
7
In the Settings window for Electrode Reaction under Stoichiometric Coefficients:
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In the Number of participating electrons n text field, enter 2.
8
Under Equilibrium Potential, in the Equilibrium potential Eeq text field, enter Eeq_Ni.
9
Under Electrode Kinetics from the Kinetics expression type list, select Butler–Volmer. In the Exchange current density i0 text field, enter i0_Ni.
Define a Second Set of Electrode Surface and Electrode Reaction Nodes
Duplicate the cathode node to create the anode, and add the hydrogen reaction.
1
In the Model Builder window, right-click Component 1 (comp1) > Secondary Current Distribution (cd) > Electrode Surface 1 and choose Duplicate.
2
Locate the Boundary Selection section and select Cathode from the Selection list.
3
Under Electrode Phase Potential Condition select Average Current Density and type Iavg in the il, average text field.
4
Add the hydrogen evolution reaction. In the Model Builder under Secondary Current Distribution, right-click Electrode Surface 2 and choose Electrode Reaction .
5
In the Settings window for Electrode Reaction 2 locate the Stoichiometric Coefficients section. Set the Stoichiometric coefficient for Ni to 0.
6
In the Settings window for Electrode Reaction 2 locate the Electrode Kinetics section.
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From the Kinetics expression type list, choose Cathodic Tafel equation.
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In the i0 text field, type i0_H.