Metal supported solid oxide fuel cells (MS-SOFC) possess several advantages like good mechanical property, easy assembling, fast start-up and capability to maintain redox stable due to fuel leakage. However, it has been a critical challenge to deposit cathode on the metal supported cell in the oxidizing atmosphere, which is mainly limited by the low calcination temperature yielding vulnerable electrolyte-electrode interface. The cathodes prepared in the protecting atmosphere are also not satisfied, instead it will increase the complexity of the cell fabrication process.

Lower down the cathode deposition temperature using aqueous infiltration has become one of the optimized methods for MS-SOFC. Also, we have proposed an alternative way for the fabrication of metal supported single cell with robust cathode through whole cell reduction. Here, we present results of both above two approaches for the fabrication of nano-structured cathodes in MS-SOFC. The cells in this study are based on Fe-Ni (1:1 in mol ratio) support, Fe-Ni/YSZ anode and YSZ electrolyte prepared through tape-casting, thermal isostatic pressing and co-firing.

As illustrated in the following schematic configuration, La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) cathodes were deposited in the porous YSZ layer of the pre-reduced Ni-Fe|Ni-Fe-YSZ||YSZ||P-YSZ substrate by infiltration and fired at the cell operation temperature around 700 ^oC. A-site deficiency of ~4-8% was introduced into LSCF cathode and was expected to enhance the sintering activity of LSCF nano particles at low calcination temperature and to enhance the cathode performance by the excess cobalt and iron oxide at LSCF surface. As in the second approach, Sr_0.95Ti_0.3Fe_0.63Ni_0.07O_3-δ – Gd_0.1Ce_0.9O_1.95 (STFNi-GDC) graded cathode will be screen printed on the NiO-Fe₂O₃|NiO-Fe₂O₃-YSZ||YSZ|GDC substrate and fired at high temperature in air as normal cathode preparation procedure. Then the whole cell will be reduced in H₂-Ar to obtain Fe-Ni alloy support and reduced STFNi cathode with in-situ exsolved (Fe,Ni) alloy nano particles anchored in the oxide surface. During the cell test, the reduced STFNi-(Fe,Ni) will be re-oxidized in air, forming the surface decorated iron and cobalt oxide particles, which were presumably to be expected to increase the cathode performance through improvement of oxygen surface exchange coefficient.