Using Faraday’s laws for an electrode reaction, m, at the interface between the electron and ion conducting phase this corresponds to
where ΔHm is the enthalpy change of the reaction, and
ΔGm is the
Gibbs free energy of the reaction,
ΔGm, defined as
where ΔSm is the net entropy change. The equilibrium potential is related to
ΔGm in the following way:
In Equation 3-2,
ηm,tot is the total overpotential, which is defined as
The total heat source due to the electrochemical reactions, QEC, for an electrode surface is the sum of all individual heat sources of the electrode reactions according to