Redox stability of metal-supported fuel cells with nickel/gadolinium-doped ceria anode

The Relation of Microstructure, Materials Properties and Impedance of SOFC Electrodes: A Case Study of Ni/GDC Anodes

“…However, GDC is a mixed-conducting, surface-active electrode material, so the very high GDC surface area and sufficient porosity are decisive for the electrode kinetics. Moreover, this microstructure was proven to be mechanically very stable during redox cycling [3].…”

“…In addition to the electrode transmission line, this circuit model also includes the element L wire , representing the wire inductance, R YSZ for the electrolyte resistance, CPE int as a constant phase element for interfacial capacitance and R int for the interfacial resistance. The interfacial resistances and capacitances depend on the cell preparation procedure; they are likely different for symmetrical model cells, in which the electrodes are sintered on a dense electrolyte, and full SOFCs, in which the electrolyte is sputter-deposited on top of the already sintered anodes (Plansee MSC concept [3,4,7,55,56]) or co-sintered with the anodes (in typical anode supported cells). However, when the ion conducting phase in the electrode is the same as the electrolyte, e.g., Ni/YSZ [24,30,34,57] anodes or for LSM/YSZ cathodes [33], the interfacial resistance is often negligible.…”

“…Metal-supported solid oxide fuel cells (MSCs) offer a variety of advantages over anode, or electrolyte supported cells, such as lower material costs, easier stacking (e.g., by welding) [1,2], mechanical robustness and fast heating rates. These properties, together with the potential for high power densities (>2 A/cm 2 ) proven on cell level tests [3,4], render this cell type most suited for mobile applications [3,[5][6][7][8][9]. The operating temperature of MSCs should be not more than 700 • C to prevent excessive oxidation of the metallic substrate [10], which requires the use of thoroughly optimized electrodes to achieve the power density desired for a successful application in the automotive sector.…”

“…Recently, power densities above 2 W/cm 2 [11] at 700 • C were demonstrated for metal-supported fuel cells with Ni/Ce 0.9 Gd 0.1 O 1.95-δ (Ni/GDC, or gadolinium-doped ceria) cermet anodes prepared equally to those used in this study. For these cells, electrolyte and cathode processing also had to be thoroughly optimized [3,4,7,11,12]. Additionally, MSCs with PrO x cathode and Ni/Sm-doped ceria anode catalysts infiltrated into porous zirconia backbone exhibited reasonably high performance [13].…”

Oxidation of porous stainless steel supports for metal-supported solid oxide fuel cells

“…Ferritic stainless steels have been conventionally used as the standard material of choice for MS-SOFC supports as they offer acceptable oxidation rate below about 750 °C, remain less expensive when compared to oxidation-resistant alloys such as Hastelloy and Inconel, and show coefficient of thermal expansion (CTE) in the range 10.4 to 11.4 ppm/K [5], matched with the CTE of standard zirconia-based electrolytes. A range of specific ferritic stainless steel alloy compositions have been successfully used as supports for MS-SOFCs, including 430, 434, and Cr26-Fe ITM [6][7][8].…”