Metallic Sponge Integrated solid oxide fuel cell

Metal-supported solid oxide fuel cell (MS-SOFC) provides significant advantages over conventional ceramic including reduction in cost, ruggedness, and tolerance to rapid thermal and redox cycling. Many materials have been recently investigated as metal supports for SOFC and are typically either nickel or iron based. In particular, ferritic stainless steels have received significant interest due to their low cost and the thermal compatibility with YSZ and CGO electrolyte materials. In order to improve the mechanical strength and the creep resistance of the stainless steel trace levels of Mo, Ti and Y2O3 are generally added to the metal composition. Particularly the addition of Al can improve the oxidation resistance by forming an Al2O3 scale at the surface of the metal that dramatically increases the lifetime of the cell at temperatures below 650°C. Despite the recent progresses in the MS-SOFC production however, the power density of these cells remained mediocre compared to the anode supported ones and the problems related to metal degradation and cations interdiffusion between anode and substrate are still unsolved. One further issue still to be adequately solved is the integration of the ceramic layers onto a metal substrate using cheaper and easily scalable manufacturing techniques. In this work an innovative metal supported half-cell was developed and characterized. In this cell configuration, the metallic substrate is exploited either as supporting element, to guarantee structural stability and flexibility to the entire cell and as current collector similarly to a conventional supporting electrode. The supporting element/current collector is therefore formed by an anodized Al-Cr-metal foam to produce a protecting Al2O3 scale and impregnated with Ni-based cermet to regain the necessary ionic/electronic conductivity. A NiO-based anode was then applied on top of the sponge to reduce its roughness to the low level necessary to deposit a dense YSZ electrolyte. This functional anode layer was screen printed using different ink compositions to produce an engineered porosity gradient. A conventional half-cell was also produced in order to compare the electrochemical performances of these cells with the one of the innovative metal-supported one.