Lanthanum strontium manganites

To meet the requirements for electronic conductivity in both the SOFC anode and cathode, a metallic electronic conductor, usually nickel, is typically used in the anode, and a conductive perovskite, such as lanthanum strontium manganite (LSM), is typically used in the cathode. Because the electrochemical reactions in fuel cell electrodes can only occur at surfaces where electronic and ionically conductive phases and the gas phase are in contact with each other (Figure 6.1), it is common... 

Currently, the standard SOFCs use yttria-stabilized zirconia (YSZ) (see Section 2.4.3) containing typically 8 mol% of Y02 as the electrolyte, a ceramic metal (a cermet) composed of Ni plus YSZ as the anode, and lanthanum strontium manganite (LSM) perovskite (La Sr, MnO,, ) as the cathode material [5,7,9,135],... 

In a 1999 letter to Nature (Perry Murray etal., 1999), from North Western University, Illinois, the authors record the first laboratory achievement of useful oxidation rates for direct methane electrochemical oxidation, using an IT/SOFC. The cathode structures were porous lanthanum strontium manganite (LSM) on porous ( 203)0.15 (Ce02)o,85 or YDC. The anodes were cermets, porous YSZ with nickel in the pores. The laboratory operating temperatures were in the range 500-700 °C. The account of the North Western work, reporting on new anode types, continues on pp. 921-924 of Williams (2002). 

Misuyasu, H. et al.. Microscopic analysis of lanthanum strontium manganite yttria-stabilized zirconia interface. Solid State Ionics, 100, 11-15 (1997). 

Ke)rwords Lanthanum Strontium Manganite/SOFC Cathode/Magnetic Sensors/Oxidation... 

The electronic conductors commonly used for SOFCs are lanthanum strontium manganite (LSM) for cathodes and nickel metal for anodes. The anodes are prepared in situ by reduction of a nickel oxide/ electrolyte composite. 

In FC and electrolysis operating modes, the performance of the oxygen electrode decreases in the order lanthanum strontium cobalt ferrites (LSCFs) > lanthanum strontium ferrites (LSFs) > lanthanum strontium manganites (LSMs). The degradation stability of LSCFs and LSFs in electrolysis mode is better than that of LSMs and YSZ. 

Wandekar, R.V. Wani, B.N. Bharadwaj, S.R. (2009). Crystal Structure, Electrical Conductivity, Thermal Expansion and Compatibility Studies of Co-substituted Lanthanum Strontium Manganite System Solid State Science, Vol. 11, No. 1, 0anuary 2009), pp. 240-250, ISSN 1293-2558... 

Jiang SP (2008) Development of lanthanum strontium manganite perovskite cathode matraials of solid oxide fuel cells a review. J Mater Sci 43 6799-6833... 

The oxygen reduction reaction occurs at the cathode. Nearly all candidate cathode materials are based on perovskite oxides such as lanthanum strontium manganite (LSM). However, the oxygen reduction reaction is particularly affected by lower operating temperatures with kinetics and transport processes that are thermally activated. The development of materials with higher electrochemical activities for the oxygen reduction reaction is critical for the development of IT-SOFCs with higher efficiencies. 

Table 18.2 Comparison of cathodes among lanthanum strontium manganites, ferrites, and cobaltites in their chemical reactivity, functionality as cathode, and tolerance against Cr poisoning...

The anode of the lightweight SOFC is made from Nickel oxide (NiO) and yttria-stabilized zirconia. For the electrolyte, yttria-stabUized zirconia is also used, while the cathode is made from lanthanum strontium manganite (LSM) (cf. previous section). The same material is used for the contact layer. Lanthanum strontium chromite is applied as a ceramic protective coating for chromium retention. The noble gas argon is used as an auxiliary medium in the vacuum plasma spraying process [71]. 

Anode - Reaction site for oxidation of water (creation of O2) - Porous layer (to facilitate the evacuation of the gas produced) - Perovskite-type oxide - The materials typically used are LSM (LaSrxMni.x03) or LSCF - Many other alternatives are possible - LSM = Lanthanum strontium manganite -LSCF = Lanthanum cobalt strontium ferrite... 

LSM (Lanthanum Strontium Manganite). For the electrodes, Lai Sr Mn03 is a good electronic conductor. To compensate the decrease of positive charge due to the substitution of La " " cations by Sr + cations, some manganese cations change their degree of oxidation from +3 to +4. The electrons can hop between the Mn + and Mn " ". The... 

Lanthanum Strontium Manganites for Application as Cathodes in Solid... 215... 

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