Electrode properties of doped Pr₂NiO₄-based oxide cathode for intermediate-temperature SOFCs

K₂NiF₄-type Pr₂NiO₄ doped with Cu, CuGa, or Co (Pr₂Ni_0.9Cu_0.1O₄, Pr₂ Ni_0.75Cu_0.25O₄, Pr _1.91Ni_0.71Cu_0.24Ga_0.05O ₄, or Pr₂Ni_0.9Co_0.1O₄) were synthesized by a solid-state reaction for use as cathodes in an intermediate-temperature (500-700° C) solid oxide fuel cell (IT-SOFC). Pr₂NiO₄, Pr₂ Ni_0.9Cu _0.1O₄, Pr₂ Ni_0.75Cu _0.25O₄, Pr_1.91Ni_0.71Cu _0.24Ga_0.05O₄, and Pr₂Ni _0.9Co_0.1O₄ crystallize in the space group Bmab. Single test cells with samarium oxide doped ceria (SDC) as the electrolyte, Ni-SDC cermet as the anode, and the above-mentioned cathode material were fabricated for cell performance measurements at 700°C. Current interruption measurements and electrochemical impedance spectroscopic analysis revealed that the cathode properties of Pr₂NiO₄, Pr₂ Ni _0.9Cu_0.1O₄, Pr₂ Ni _0.75Cu_0.25O₄, and Pr_1.91Ni _0.71Cu_0.24Ga_0.05O₄ were comparable to that of La_0.6Sr_0.4Co_0.2Fe _0.8O₃ (LSCF) and the cathode properties of Pr ₂NiO₄ were improved by doping with Cu or CuGa at the Ni site of Pr₂NiO₄.