Fuel cells interconnects

Fergus JW. Lanthanum chromite based materials for solid oxide fuel cell interconnects. Solid State Ionics 2004 171 1-15. 

Huang W and Gopalan S. Bi-layer structures as solid oxide fuel cell interconnections. J. Power Sources 2006 154 180-183. 

Mori M and Hiei Y. Thermal expansion behavior or titanium-doped La(Sr)Cr03 solid oxide fuel cell interconnects. J. Am. Ceram. Soc. 2001 84 2573-2578. 

Key words Solid Oxide Fuel Cell/Interconnect/Ferritic Steel/High Temperature Conductivity... 

Fuel cell - Interconnect plate for a plcinar solid oxide fuel cell (56)... 

Hilpert, K., Das, D., Miller, M., Peck, D.H., and Weiss, R. (1996) Chromium vapor species over solid oxide fuel cell interconnect materials and their potential for degradation processes. J. Electrochem. Soc., 143 (11), 3642-3647. 

T. Uehara, N. Yasuda, M. Okamoto, and Y. Baba, Effect of Mn-Co Spinel Coating for Fe-Cr Ferritic alloys ZMG232L, and 232J3 for Solid Oxide Fuel Cell Interconnects on Oxidation Behavior and Cr-Evaporation, J. Power Sources, 196, 7251-56(2011)... 

Kuo LJH, Vora SD, Singhal SC (1997) Plasma spraying of lanthanum chromite films for solid oxide fuel cell interconnection application. J Am Ceram Soc 80 589-593... 

Cooper, L., Benhaddad, S., Wood, A. Ivey, D.G. (2008). The effect of surface treatment on the oxidation ferritic stainless steels used for solid oxide fuel cell interconnects. Journal of Power Sources. Vol. 184, pp. 220. 

Pedersen, T.F., Linderoth, S. and Laatsch, J. (2004) Oxidation behaviour of iron-chromium steels for solid oxide fuel cell interconnect. Proceedings of the sixth European Solid Oxide Fuel Cell Forum, 28 June-2 July 2004, Lucerne, Switzerland, Vol. 2, pp. 897-907. 

S. Megel, E. Girdauskaite et al.. Area specific resistance of oxide scales grown on ferritic alloys for solid oxide fuel cell interconnects. J. Power Sources (2010). doi 10.1016/ 2010.09.003... 

II. Ease of electrical connection Here the main problem is that of efficient electrical current collection, ideally with only two electrical leads entering the reactor and without an excessive number of interconnects, as in fuel cells. This is because the competitor of an electrochemically promoted chemical reactor is not a fuel cell but a classical chemical reactor. The main breakthrough here is the recent discovery of bipolar or wireless NEMCA,8 11 i.e. electrochemical promotion induced on catalyst films deposited on a solid electrolyte but not directly connected to an electronic conductor (wire). 

The cathode of a battery or fuel cell must allow good ionic conductivity for the ions arriving from the electrolyte and allow for electron conduction to any interconnects between cells and to external leads. In addition these properties must persist under oxidizing conditions. An important strategy has been to employ layered structure solids in which rapid ionic motion occurs between the layers while electronic conductivity is mainly a function of the layers themselves. 

The perovskite oxides used for SOFC cathodes can react with other fuel cell components especially with yttria-zirconia electrolyte and chromium-containing interconnect materials at high temperatures. However, the relative reactivity of the cathodes at a particular temperature and the formation of different phases in the fuel cell atmosphere... 

The interconnect material is in contact with both electrodes at elevated temperatures, so chemical compatibility with other fuel cell components is important. Although, direct reaction of lanthanum chromite based materials with other components is typically not a major problem [2], reaction between calcium-doped lanthanum chromite and YSZ has been observed [20-24], but can be minimized by application of an interlayer to prevent calcium migration [25], Strontium doping, rather than calcium doping, tends to improve the resistance to reaction [26], but reaction can occur with strontium doping, especially if SrCr04 forms on the interconnect [27],... 

Interconnects are formed into the desired shape using ceramic processing techniques. For example, bipolar plates with gas channels can be formed by tape casting a mixture of the ceramic powder with a solvent, such as trichloroethylene (TCE)-ethanol [90], Coating techniques, such as plasma spray [91] or laser ablation [92] can also be used to apply interconnect materials to the other fuel cell components. 

Zhu WZ and Deevi SC. Development of interconnect materials for solid oxide fuel cells. Mater. Sci. Eng. A 2002 A348 227-243. 

Nishiyama H, Aizawa M, Sakai N, Yokokawa H, Kawada T, and Dokiya M. Property of (La,Ca)Cr03 for interconnect in solid oxide fuel cell (part 2). Durability. J. Ceram. Soc. Japan 2001 109 527-534. 

Zhou X-L, Ma J-J, Deng F-J, Meng G-Y, and Liu X-Q. A high performance interconnecting ceramic for solid oxide fuel cells (SOFCs). Solid State Ionics 2006 177 3461-3466. 

Zhou X, Deng F, Zhu M, Meng G, and Liu X. Novel composite interconnecting ceramics LaojCao jCrOj j/ Cc02Sm08O 9 for solid oxide fuel cells. Mater. Res. Bull. 2007 42 1582-1588. 

Meschke F, Singheiser L, and Steinbrech RW. Mechanical properties of doped LaCr03 interconnects after exposure to SOFC-relevant conditions. In McEvoy AJ, editor. European Solid Oxide Fuel Cell Forum Proceedings Vol. 2. Lucerne, Switzerland The European Fuel Cell Forum, 2000 865-873. 

Extensive work has been reported on the deposition of individual cell layers and of full anode-electrolyte-cathode fuel cells on metallic interconnect substrates, much of it by VPS, with no sintering or other post-deposition heat treatments required [112]. However, so far relatively thick YSZ electrolytes, approximately 25 to 35 pm, have been needed to provide sufficient gas tightness [108, 114], so further optimization of the process is required to produce thinner, gas-tight electrolytes. Peak power densities of 300 mW/cm2 have been reported at 750°C for APS single cells [114], with four-cell stacks exhibiting power densities of approximately 200 mW/cm2 at 800°C [55],... 

Summarizing progress in the field thus far, the book describes current materials, future advances in materials, and significant technical problems that remain unresolved. The first three chapters explore materials for the electrochemical cell electrolytes, anodes, and cathodes. The next two chapters discuss interconnects and sealants, which are two supporting components of the fuel cell stack. The final chapter addresses the various issues involved in materials processing for SOFC applications, such as the microstructure of the component layers and the processing methods used to fabricate the microstructure. 

The next two chapters discuss two supporting components of the fuel cell stack —specifically, interconnects and sealants. The interconnect conducts the electrical current between the two electrodes through the external circuit and is thus simultaneously exposed to both high oxygen partial pressure (air) and low oxygen partial pressure (fuel), which places stringent requirements on the materials stability. Ceramic interconnects have been used, but metallic interconnects offer promise... 

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