The Electrode, Shell interface solves for the electric potential ϕs (SI unit: V) on a boundary, using the following governing equation:

where ∇T is the tangential gradient operator, s (SI unit: m) is the electrode layer thickness, and in (SI unit: A/m2) are the sum of all currents flowing out from the electrode (in the normal direction to the boundary). Furthermore, is (SI unit: A/m2) is the tangential current density vector along the electrode boundary, defined as

where σs is the electric conductivity (SI unit: S/m). The next section discusses Coupling to Other Physics Interfaces.