Break‐down of Losses in High Performing Metal‐Supported Solid Oxide Fuel Cells

Abstract

Metal supported SOFC designs offer competitive advantages such as reduced material costs and improved mechanical robustness. On the other hand, disadvantages might arise due to possible corrosion of the porous metal parts during processing and operation at high fuel utilization. In this paper we present the results of performance and stability improvements for a metal supported cell developed within the European project METSOFC and the Danish National Advanced Technology Foundation. The cells consist of a porous metal backbone, a metal / zirconia cermet anode and a 10ScYSZ electrolyte, cofired in hydrogen. The electrochemically active parts were applied by infiltrating CGO-Ni precursor solution into the porous metal and anode backbone and screenprinting (La,Sr)(Co,Fe)O 3 -based cathodes. To prevent a solid state reaction between cathode and zirconia electrolyte, CGO buffer layers were applied in between cathode and electrolyte. The detailed electrochemical characterization by means of impedance spectroscopy and a subsequent data analysis by the distribution of relaxation times enabled us to separate the different loss contributions in the cell. Based on an appropriate equivalent circuit model, the ohmic and polarization losses related to the gas diffusion in the metal support, the electrooxidation in the anode functional layer and the oxygen reduction in the mixed ionic electronic conducting cathode were determined. An additional process with a rather high relaxation frequency could be attributed to the formation of insulating interlayers at the cathode/electrolyte-interface. Based on these results, selective measures to improve performance and stability, such as (i) an improved PVD-deposited CGO buffer layer, (ii) LSC-CGO based in-situ sintered cathodes and (iii) reduced corrosion of the metal support were adopted and validated.

Electrochemical Performance of Plasma Sprayed Metal Supported Planar Solid Oxide Fuel Cells

“…As this process is usually related to gas diffusion polarization in the substrate, 28 there should be no difference as all cells exhibited the same type of metal support. As previously shown in, 29 the high frequency process at a relaxation frequency of ∼1 MHz seems to be related to the formation of a strontium zirconate interlayer. Thus the related losses can be avoided by introducing a dense gadolinia doped ceria (GDC) interlayer.…”

Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

“…The H 2 O content of used fuel composition of the present study is significantly lower (4-15%) than in Ref. 32, which gives a higher gas diffusion/conversion resistance and would in fact lead to an even higher tolerance than depicted in Figure 9. Most studies within the literature report the effect of sulfur poisoning as a voltage drop or performance drop of the whole fuel cell.…”

Spinel-based coatings for metal supported solid oxide fuel cells

“…[1,2] Some recent research has been focused on a new cell design for metal-supported SOFCs (MS-SOFCs) based on a multi-layered structure obtainable by cost effective materials processing techniques such as tape casting, lamination, co-sintering and infiltration. [1][2][3][4][5][6] In this design, illustrated in Figure 1, the cell has a layered structure supported by a porous and highly electronically conducting FeCr-steel backbone. The anode layer consists of FeCr steel-scandium doped yttrium stabilised zirconia (ScYSZ) cermet infiltrated with CeO 2 and Ni.…”