Ni1−xCox/YSZ cermet anodes for solid oxide fuel cells

Nanocrystalline and homogeneous powder mixtures of (Ni_1−xCo_xO_y)+YSZ were obtained by combustion synthesis, and reduced in H₂ at 800 °C to obtain Ni_1−xCo_x/YSZ cermets, and three layer symmetrical cells cermet/YSZ/cermet. These three layer cells were co-firing at 1450 °C, and then reduced to obtain porous Ni_1−xCo_x/YSZ cermet layers with good adhesion to the electrolyte. Results obtained under OCV show that partial substitution of Ni with Co lowers the polarisation resistance, especially the main contribution which is usually most dependent on the cermets microstructure. This trend is reverted for high fractions of Co, and the polarisation resistance obtained for Co/YSZ cermets is much higher than for Ni/YSZ. The low frequency contribution of the polarisation resistance was mainly dependent on the partial pressures of H₂ and H₂O, and is less dependent on the substitution of Ni with Co.