Solid electrolytes for SOFCs

When doped Ce02 is applied as a solid electrolyte for SOFCs, a change in... 

When an LaGaOs-based oxide is applied as a solid electrolyte for SOFCs, reactivity and/or interdiffusion with electrode materials becomes a critical issue. When LSM was used as the cathode material, interdiffusion of Mn into LSGM was... 

The electrical conductivity of ScSZ is strongly related to the microstructure and for nanocrystalline specimens can be dominated by electronic transport in the temperature range of 600-900 C and P02 < 10 atm, while microcrystalline specimens show only ionic conductivity [7, 13], The results of the study of electrical transport in both nanocrystalline YSZ and ScSZ thin films are showing that their non-stoichiometry can be controlled by the microstructure and in addition that the electrical conductivity is also influenced by the interaction between lattice defects and type of acceptor dopants. The large increase in electronic conductivity observed for nanocrystalline ScSZ suggests that it may find use as a buffer layer on the anode site of a solid electrolyte in SOFC, which can be YSZ or microcrystalline ScSZ. Such compatibility between the electrode and... 

For the practical application of the oxide ion conducting solid electrolytes for the SOFCs, there is another problem that they usually need high operation temperature over 800°C. In fact, the SOFCs based on the YSZ thin film electrolyte cannot provide acceptable power output due to the fundamental limit of YSZ that it is difficult to obtain enough conductivity below 650°C. The ceria-based oxides are. 

There are several types of fuel cells being developed for a variety of applications and these have been extensively discussed in the open literature. Unlike other variants, the SOFC is entirely solid state with no liquid components. Operation at elevated temperature is needed to achieve the necessary level of conductivity in the cell s solid electrolyte for it to operate efficiently. With an outlet temperature in the range of 900-1000°C, the efficiency of the eell alone is about 50 percent. 

The most investigated oxide-conducting solid electrolytes for potential use in SOFCs belong to the fluorite-type solid solutions with the general formula MO -M O or M0 -M"203, where MO2 is the basic oxide and M O or M"203 the dopant with... 

YSZ is so far the most widely used solid electrolyte for application in high temperature SOFC. For many years, the zirconium oxide is already known as a conductor of oxygen ions. 

Steele BCH. Appraisal of Ce, yGdy02 y/2 electrolytes for IT-SOFC operation at 500°C. Solid State Ionics 2000 129 95-110. 

Xu X, Jiang Z, Fan X, and Xia C. LSM-SDC electrodes fabricated with an ion-impregnating process for SOFCs with doped ceria electrolytes. Solid State Ionics 2006 177 2113-2117. 

In a SOFC, there is no liquid electrolyte present that is susceptible to movement in the porous electrode structure, and electrode flooding is not a problem. Consequently, the three-phase interface that is necessary for efficient electrochemical reaction involves two solid phases (solid electrolyte/electrode) and a gas phase. A critical requirement of porous electrodes for SOFC is that they are sufficiently thin and porous to provide an extensive electrode/electrolyte interfacial region for electrochemical reaction. 

PEFC The PEFC, like the SOFC, has a solid electrolyte. As a result, this cell exhibits excellent resistance to gas crossover. In contrast to the SOFC, the cell operates at a low 80°C. This results in a capability to bring the cell to its operating temperature quickly, but the rejected heat cannot be used for cogeneration or additional power. Test results have shown that the cell can operate at very high current densities compared to the other cells. However, heat and water management issues may limit the operating power density of a practical system. The PEFC tolerance for CO is in the low ppm level. 

The solid oxide electrolyte must be free of porosity that permits gas to permeate from one side of the electrolyte layer to the other, and it should be thin to minimize ohmic loss. In addition, the electrolyte must have a transport number for O as close to unity as possible, and a transport and a transport number for electronic conduction as close to zero as possible. Zirconia-based electrolytes are suitable for SOFCs because they exhibit pure anionic conductivity over a wide... 

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