Electrochemical characterization of B-site cation-excess Pr2Ni0.75Cu0.25Ga0.05O4+δ cathode for IT-SOFCs

The B-site cation-excess K2NiF4-type structure oxide, Pr2Ni0.75Cu0.25Ga0.05O4+δ (PNCG) is investigated as a cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). XRD result shows that PNCG cathode is chemically compatible with the electrolyte Gd0.1Ce0.9O2−δ (GDC) at 900oC for 5h. The PNCG material exhibits a semiconductor to metal transition around 425oC. The thermal expansion coefficient (TEC) of the PNCG sample is 12.72×10−6K−1 between 30 and 850oC in air. The polarization resistance (Rp) of PNCG cathode on GDC electrolyte is 0.105, 0.197 and 0.300Ωcm2 at 800, 750, 700°C, respectively. A maximum power density of 371mWcm−2 is obtained at 800°C for single-cell with 300μm thick GDC electrolyte and PNCG cathode. The results of this study demonstrate that PNCG can be a promising cathode material for IT-SOFCs.