Use the Periodic Condition to define a periodic relation between two boundaries — for instance, in a model describing a repetitive unit cell.

Use the Apply for electrolyte phase and Apply for electrolyte checkboxes to enable the periodic condition for the electrolyte and electrode phase potentials, respectively.

By specifying a Potential difference, an offset in potential (typically per unit cell) can be prescribed.

For more information, see Periodic Boundary Conditions in the COMSOL Multiphysics Reference Manual.