Preparation of porosity-graded SOFC anode substrates

Porosity graded anode substrates for solid oxide fuel cells are considered to optimise the gas transport through the substrate by maintaining a high electrochemical activity for fuel oxidation at the anode/solid electrolyte interface. In this work, the fabrication of porosity graded anode substrates, made from nickel oxide and yttria-modified zirconia and produced by dry uni-axial pressing, are described. Using carbon as pore formers and adjusting the particle size distribution in the ceramic NiO-YSZ masses, samples with gradually changing porosity are built up. The sintering behaviour of the individual layers is analysed and partly adjusted so the multi-layer support can be co-fired together with the YSZ electrolyte layer. In the oxidized state, four-layer, porosity graded anode supported half-cells with a dense YSZ electrolyte are demonstrated.