The Reference Electrode
In order to relate the electrolyte phase potential to an experimentally measurable voltage, a reference electrode, defined by it’s reaction stoichiometric coefficients, is deployed in the model using the generic reaction formula
(3-20)
where si and Xi define the stoichiometric coefficients and species of the electrolyte phase, and s’j and Y’j define the stoichiometric coefficients and species of an adjacent (electrode) phase, respectively, and ne,ref the number of electrons participating in the reaction.
The gradient of the electrolyte phase potential, used for defining the chemical potential is defined as
(3-21)
The stoichiometry of the reference electrode can also be used to define a steady-state convective velocity of the electrolyte for the case when all electrode reactions in a cell have the same stoichiometry as the reference electrode. For this case, the convective velocity may be calculated as
(3-22)