Counter Electrodes and Overall Charge Balance
The Electroanalysis charge conservation model does not solve explicitly for the electrolyte potential in the domains. This has the implication that an overall charge balance of a modeled cell does not follow naturally as a result of the domain potential equation (as is the case for instance when solving for Ohm’s law in the Secondary Current Distribution interface).
In order to model a charge balance of a cell with an arbitrary number of working electrodes and counter electrodes, the solution is to add an extra degree of freedom for the counter electrode potential,
φ
s
, CE
, and then solve for this potential to fulfill the following current balance over all electrode surfaces:
(3-16)
The counter electrode potential is used in the overpotential,
η
, in the kinetics expression(s) on the counter electrode.
(3-17)
Note that only one counter electrode potential degree of freedom is added in the model, regardless of the number of counter electrodes that are active.
Domain Equations for the Electroanalysis Case
