THE DISSIPATED ENERGY OF ELECTRODE SURFACES - TEMPERATURE JUMPS FROM COUPLED TRANSPORT PROCESSES

Nonequilibrium thermodynamics for surfaces has been applied to the ele ctrode surfaces of an electrochemical cell. It is shown that the tempe rature of the surface differs from that of the adjacent electrolyte an d electrode, and that a temperature jump exists across the surface. Ma thematical expressions are derived for the temperature profiles of two cells at steady-state conditions. Methods for estimating transport co efficients for the coupled transport processes at the electrode surfac e are discussed. Possible numerical results for the temperature profil e, the overpotential, and the dissipated energy are reported. The resu lts reflect the relative importance of heat conductivities, electric c onductivities, and the Peltier coefficients for the electrode surface phenomena in combination with bulk properties. Significant temperature jumps may occur at normal electrolysis conditions 10(3) to 10(4) A m( -2), and for temperature jump coefficients which are smaller than 10(3 ) J s(-1) K-2 m(-2). The overpotential may have contributions from the Peltier coefficients for the surface larger than the ohmic contributi on. The method of analysis gives new information useful for heat contr ol of electrochemical cells, electrode kinetic studies, and interpreta tion of overpotentials.