Components of SOFC

For a SOFC, the typical fuel gas contains 0.23 bar H2, 0.03 bar water, 0.06 bar CO2 and 0.2 bar CO, with N2 yielding balance of 1 bar. Corresponding to the difference of oxygen partial pressure in fuel and air compartments, the fuel and air compartments of fuel cell have different potentials. The magnitude of current the generated in the fuel cell depends upon the rate of conversion for CO and H2 to CO2 and H2O, respectively. To achieve higher powers, the cathodic and anodic 

Electrolyte Yttria stabilised Zirconia (30 0 pm thickness) by EVD technique Oxygen ion conductivity Mechanical strength Gas tightness 

Interconnect Pt, Mn-doped cobalt chromite, doped lanthanum chromite ( 100 pm thick by plasma spray) High electronic and thermal conductivity High mechanical strength 

Anode Pt, Ni-Zr02 Cermet, Ni-YSZ Cermet ( 150 pm thick by EVD or Slurry deposition) High porosity Electronic conductivity Large triple phase boundary sulphur tolerance 

Cathode Pt, Lai- Sr MnOa, Lai Sr e03, Lai ,Sr,Coi, Fej,03 High porosity Electronic conductivity Large triple phase boundary Activity for oxygen surface exchange 

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Fundamental research in the field of SOFCs started in Russia in the end of 1950s at the Institute of Electrochemistry in Sverdlovsk (now the Institute of High Temperature Electrochemistry, IHTE, Ekaterinburg). From the very outset, the works included study of solid oxide electrolytes (SOEs), electrode materials and electrode kinetics, other components of SOFC interconnects, seals, etc. 

CELLULOSE-PRECURSOR SYNTHESIS OF ELECTROCAT ALYTICALLY ACTIVE COMPONENTS OF SOFCs AND MIXED-CONDUCTING MEMBRANE REACTORS... 

Components Of SOFCs And Mixed-Conducting Membrane Reactors... 

An important component of SOFCs that governs their operating reliability to a large extent (and sometimes their manufacturing cost) is that of the interconnectors needed to combine the individual cells in a battery. These must be purely electronically conducting, chemically sufficiently stable toward the oxidizing and reducing atmospheres within the fuel cells, and free of chemical interactions with the active materials on the electrodes. 

A very limited number of materials exist that can be used to fabricate the various functional and strucmral components of SOFCs and that are sufficiently stable thermally and chemically to withstand their operating environment. As an example, take the interconnectors between cells for which mechanically weak lanthanum chromite ceramics or thermally stable high-alloy steels must be used. These materials are very expensive, so the interconnectors make a considerable contribution to the fuel cell s total cost. Numerous difficulties also arise in the selection of sealing materials. 

The components of SOFC can be made in different ways. The main differences between the preparation techniques consist of the fact that the whole ceU can be made self-supporting (i.e., the electrode/electrolyte assembly supports the stmeture of the cell and no substrate is used) or supported whereby the electrodes and electrolyte are cast onto a substrate. In the anode-supported planar SOFC concept, with a 20 pm thin electrolyte layer, the operation temperature can be reduced significantly, for example, to 800 °C [34]. This reduces the material requirements considerably. 

Good Electrochemical Contacts Among the components of SOFC, the contact surface area should be high and the current collector must regulate the desired current flow in the stack. 

Ceramic sealants have been fabricated to join the components of SOFC with reaction bonding. Anyhow, the ceramic may not exhibit CTE matching, and hence... 

Glasses in Contact with Adjacent Components of SOFC... 

The glass seal must exhibit strong bonding at the interface to keep the residual stresses as low as possible. CTE mismatch between the glass and components of SOFC lead to thermal stress, which is given by the relation ... 

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