Solid oxide fuel cells chemical thermodynamics

The principles behind this membrane technology originate from solid-state electrochemistry. Conventional electrochemical halfceU reactions can be written for chemical processes occurring on each respective membrane surface. Since the general chemistry under discussion here is thermodynamically downhill, one might view these devices as short-circuited solid oxide fuel cells (SOFCs), although the ceramics used for oxygen transport are often quite different. SOFCs most frequently use fluorite-based solid electrolytes - often yttria stabUized zirco-nia (YSZ) and sometimes ceria. In comparison, dense ceramics for membrane applications most often possess a perovskite-related lattice. The key fundamental... 

Solid Oxide Fuel Cells, Thermodynamics, Fig. 4 Chemical potential diagrams for the La-Mn-Zr-O and the La-Co-Zr-0 system and analyses in terms of the stabilization energy and the valence stability of transition metal oxides... 

Yokokawa H, Sakai N, Kawada T, Dokiya M (1991) Chemical thermodynamic compatibility of solid oxide fuel cell materials. In Grosz F, Zegers P, Singhal SC, Yamamoto O (eds) Proceedings of the 2nd international symposium on solid oxide fuel cells. Commission of European Communities, Luxembourg, pp 663-670... 

A solid oxide fuel cell (SOFC) is an electrochemical device that converts chemical energy of a fuel and an oxidant gas (air) directly into electricity without irreversible oxidation. It can be treated thermodynamically in terms of the free enthalpy of the reaction of the fuel with oxidant. Hydrogen and oxygen are used to illustrate the simplest case in the early part (Section 3.2) of this chapter. This treatment allows the calculation of the reversible work at equilibrium for the reversible reaction. Heat must also be transferred reversibly to the surrounding environment in this instance. 

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