Electrolytes perovskite compounds

LaM03 and La, xSrxMO, (M = Co, Ni and Fe) perovskites are relatively unstable compared to their manganese counterparts LaMn03 and La, xSrxMn03. The former compounds readily react with zirconia electrolytes, leading to the formation of secondary phases at temperature as low as 1000°C in air. The Co3+ ions in LaCo03 are... 

Franke and Winnick [105], using a K2S2O7 based electrolyte dispersed within the interstices of an inert K2Mg2(S04)3 matrix, were able to achieve removal efficiencies of SO2 greater than 99% at current efficiencies near 100%. A porous electrode constructed of a perovskite-type compound, Lao 8Sro.2Co03, was found to be conductive and stable in the corrosive cell environment. 

Other oxygen ion conductors that have potential use as solid electrolytes in electrochemical devices are stabilized bismuth and cerium oxides and oxide compounds with the perovskite and pyrochlore crystal structures. The ionic conductivity and related properties of these compounds in comparison with those of the standard yttria-stabilized zirconia (YSZ) electrolyte are briefly described in this section. Many of the powder preparation and ceramic fabrication techniques described above for zirconia-based electrolytes can be adapted to these alternative conductors and are not discussed further. 

Perovskite (ABO3 in which A is divalent and B is tetravalent) and pyrochlore (AaBaOi in which A is trivalent and B is tetravalent) oxide compounds have been proposed as oxygen ion conducting electrolytes for electrochemical devices. Some of the perovskite structures (e.g., BaCeO and SrCeOs) are generating interest because of... 

Many perovskite-structured oxides exhibit high oxide-ion conductivities at elevated temperatures, and have attracted significant interest for use as sohd electrolytes in, for example, SOFCs (see Chapters 9, 12 and 13). The compounds can be divided into camps with compositions or A + B + O3, of which LaGaO3 and... 

The perovskite lanthanum chromite (LaCr03) is one of the exceptional ceramic compounds that are chemically very resistant to both oxidizing and reducing ambients. Moreover, being an electronic conductor, it is eminently suitable as a bipolar connector in solid oxide fuel cells. It is evident that the thermal expansion coefficients of the different components in a fuel cell (electrolyte, electrodes, bipolar connector) must be closely matched. Doping the chromite with strontium or magnesium ions is necessary to increase its electronic conductivity as well as its sinter activity. 

Rare-earth elements are vital constituents of several prominent high-temperature solid electrolytes ranging from oxygen- or fluoride-ion conductors in the fluorite structures to protonic conductors in the doped perovskite phases and trivalent-ion conduction in Sc2(W04)3 and 3-alumina-type compounds. Solid electrolytes are considered as important for scientific studies and technological applications in vital areas such as fuel cells, batteries, sensors, process control and environmental protection. 

Crystalline inorganic electrolytes for Li-ion batteries can be divided into four main families of compounds, depending on their crystal strucmre (1) A-site deficient perovskite-type Li-ion conductors (2) Garnet-type Li-ion conductors (3) NASICON-type Li-ion conductors (4) LISICON-type Li-ion conductors. 

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