ABSTRACT
A typical solid oxide fuel cell (SOFC) includes current collectors (interconnector), a porous anode, dense electrolyte, and a porous cathode (Singhal and Kendall, 2001), as shown in Figure 6.1. The cathode-electrolyte-anode is also called membrane-electrode-assembly (MEA), which is the key component of SOFCs. The commonly used materials for the electrolyte, anode and cathode, are yttria-stabilized zirconia (YSZ), YSZ-Ni composite, and a lanthanum strontium manganate (LSM)-YSZ composite. In operation, hydrogen and carbon monoxide can react with oxygen ions to produce electrons, steam, and carbon dioxide. The produced electrons flow through the external circuit to produce power and then flow to the cathode side. In the porous cathode, oxygenmolecules reactwith electrons to produce oxygen ions, which are subsequently transported through the dense electrolyte to the porous anode to complete the cycle. Theworkingmechanisms of SOFCs are similar to those of batteries, since both devices produce
electric energy via electrochemical reactions. Batteries are essentially energy storage devices, as the reactants are stored in batteries (Yang et al., 2011). Thus, the capacity and lifetime of the batteries depend on their size. Although rechargeable batteries can be recharged and used repeatedly, the charging process is usually time-consuming. For comparison, SOFCs are energy conversion devices as the fuels and oxidants are stored outside of the cell. SOFCs can continuously generate electric energy as long as fuel and an oxidant are supplied.
