The external part of the electrode, called the conduction layer, serves as the electron collector. The electrochemical reactions occur within 10 to 20 μm from the electrolyte/electrode interface, in a zone defined as the functional layer. The latter being produced by the irreversible losses. The final products of this process depend on the fuel used but are typically electricity, water, carbon dioxide, and heat.

The oxide ions migrate through the electrolyte to the anode where they oxidize the fuel molecules producing electrons, which, in turn, flow to the cathode through the external circuit. At the cathode, oxide ions (O 2-) are formed by oxygen reduction. The electrolyte is in contact with the porous electrodes where the electrochemical reactions are carried out. The basic components of a solid oxide fuel cell are: electrolyte, anode, cathode, interconnects, and an electric circuit connected to an external load. SOFC are the most efficient among all fuel cells, and operate according to the principle shown in Figure 1. Solid Oxide Fuel Cells (SOFC) are high temperature (600–1,000 ☌) fuel cells that employ a solid ion-conducting electrolyte. There are several types of fuel cells that are classified according to the type of electrolyte and operating temperature. Fuel cells are electrochemical devices in which the chemical energy of a fuel is converted directly into electrical energy.

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