The solid oxide fuel cell (SOFC) is one of the most promising technologies for the production of electric energy, mainly due to the fact that it is virtually no pollutant. Typically, the SOFC is constituted of at least seven distinct phases: fuel, anode, electrolyte substrate (separating the two electrodes), cathode, air, and electrical interconnectors (two, completing the electrical circuit). Thermodynamics clearly shows that electrochemical systems only can be reversible when homogeneous, what it is not case of the SOFC, and therefore the application of equilibrium thermodynamics to these systems is incorrect. It is considered that the SOFC can be better described by the reaction between adsorbed species. The efficiency then is calculated as the ratio between the free energy of this reaction to the combustion heat. Estimates of thermodynamic parameters are developed for the global reaction, as well as adsorbed species reaction.
SOFC; theoretical efficiency; heterogeneous reactions; statistical mechanics
