EMF of a nonisothermal cell incorporating a mixed conductor

Abstract

An equation for the reversible emf of a solid‐state galvanic cell with a mixed conductor operating under gradients of both temperature and chemical potential is derived based on the phenomenological equations of irreversible thermodynamics and the principles of local equilibrium and charge neutrality. The equation for the emf of the nonisothermal cell with a mixed conductor contains certain integrals which are dependent on the temperature and chemical potential profiles through the solid electrolyte. Therefore, only lower and upper bonds for the emf of such a cell can be evaluated in the absence of specific data on variation of temperature and chemical potential with distance. In limiting cases, when either the temperature or the chemical potential gradient is zero, the expression derived in the study reduces to forms suggested earlier by Wagner. When electron or hole conductivity is assumed to be negligible (t_ion>0.99), an expression for an ionic conductor in coupled gradients of temperature and chemical potential is obtained.