Characterization of Sr-doped neodymium cobalt oxide cathode materials for intermediate temperature solid oxide fuel cells

With an aim to explore as cathode materials for intermediate temperature solid oxide fuel cells, the structure and properties of Nd _1-xSr _xCoO _3-δ oxides have been investigated for 0 ≤ x ≤ 0.5. The Nd _1-xSr _xCoO _3-δ system crystallizing in the orthorhombic perovskite structure exhibits a semiconductor to metal transition at x ≈ 0.3, and the electrical onductivity increases with x. The thermal expansion coefficient decreases initially with increasing x, reaches a minimum at x = 0.3, and then increases. While the increasing electrical conductivity leads to an increase in electrocatalytic activity and power density initially with x, the enhanced interfacial reactions between the cathode and the La _0.8Sr _0.2Ga _0.8Mg _0.2O _2.8 (LSGM) electrolyte result in a decline in the activity at higher values of x > 0.4. Thus the x = 0.4 sample exhibits the highest catalytic activity with a maximum power density value of 0.24 W/cm ² at 800 °C in single cells fabricated with the Ni-Ce _0.9Gd _0.1O _1.95 (GDC) cermet anodes.