The electrochemical characteristics of a La0.8Sr0.2Ni0.4Fe0.6O3 cathode electrode interfaced to La9.83Si5Al0.75Fe0.25O26{plus minus}δ apatite-type electrolyte were studied using AC impedance spectroscopy under open circuit conditions, at temperatures 600 to 800 oC and oxygen partial pressures in the range 0.1 to 20 kPa. The cathode and electrolyte powders were prepared via the Pechini method and the mechanochemical activation method, respectively. The electrocatalytic activity of the tested interface was assessed on the basis of its open circuit area specific polarization conductance , determined from the impedance data. The polarization conductance was found to increase with increasing , following power law dependence. The impedance characteristics of the system were determined by at least two different processes, corresponding to two partially overlapping depressed arcs in the Nyquist plots. The relative contribution and degree of overlap of these arcs depended on temperature and oxygen partial pressure.

Within the network of the Lower Saxony SOFC Research Cluster, a highly efficient SOFC power generator has been built. Its purpose is to supply 12 V (DC) devices and charge lead-batteries for off-grid applications, such as mobile homes or radio masts. The system is based on the Mk200 stack of Sunfire GmbH, Dresden and includes multiple innovative approaches for improved efficiency and stability.

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The TU Clausthal and CUTEC have teamed up to design, build and test a new SOFC stack architecture, based on repeating units with cells connected in parallel. This approach allows the use of electrically conducting seals like brazes and can be realized without any glass sealing. Unlike conventional (serially connected) stacks, where all cells operate at the same current but individual voltage, in this setup each cell contributes as much current as possible at a common voltage. Thereby accelerated degeneration caused by undervoltage and the associated oxidation of the nickel catalyst can be completely overcome. The concept uses two cells in electrical parallel connection with the anodes facing each other to form a repeating unit. Two designs have been realized: An all ceramic housing made from 3YSZ, sealed with reactive air brazing (RAB) and a metallic one with Crofer 22 APU housing, joined by laser beam welding.

In this study we present the preparation of SOFC half cells by electrophoretic deposition. The cathode is deposited from a methyl ethyl ketone (MEK) suspension on dense apatite type lanthanum silicate (ATLS) pellets using a constant voltage. ATLS are a new class of electrolytes, which provides good oxygen permeability even at temperatures below 800°C. As cathode materials we used La2Ni0.8Cu0.2O4+δ (LNC) and La0.8Sr0.2Ni0.6Fe0.4O3 (LSNF). A conductive layer on the ATLS material was used to provide the necessary conductivity for electrophoretic deposition (EPD) process. For the preparation of suitable suspensions the charging behaviour and particle size of the different powders were investigated by means of zeta-potential and laser scattering measurements. When the electrophoretic mobility of the suspended particles was not sufficient iodine was added. Deposition kinetics were determined prior to preparation of the half cells. EPD parameters as well as sintering conditions were optimized in order to gain well adhering porous cathode layers.