Interface Resistance of an SOFC Cathode with a Pr1-xTbxO2-d Active Layer

We investigated the use of Pr1-xTbxO2-d (x=0.0-1.0) material for active layer in SOFC cathode. Pr1-xTbxO2-d (x=0.0-1.0) in single-phase fluorite structure were successfully synthesized. They are solid solution of Pr6O11 and Tb4O7. When the x is between 0.3 and 0.6, the phase transition between room temperature and 800oC were eliminated Coin cells with GDC electrolyte and Pr1-xTbxO2-d (x=0.0-1.0) active layer and LaNi0.6Fe0.4O3 (LNF) current collecting layer were made to clarify the effect of this active layer. The interface resistance of these cathodes was measured with an AC impedance method at 800oC. The cathodes withPr1-xTbxO2-d (for all composition) active layer performed better than that of reference cathode, which has no active layer (consisting only LNF layer).

DC 4-Point Measurement for Total Electrical Conductivity of SOFC Cathode Material

Conductive oxides are widely studied as cathode materials for electrochemical cells, such as solid oxide fuel cells (SOFCs), because of their chemical stability and high electrical conductivity at high temperatures (800–950 °C). The cathode is a key component of SOFCs, accounting for the greatest resistance loss among the SOFC components. It is important to precisely determine the conductivity of the cathode material, but it is difficult to achieve consistency among measurements because of errors caused by differences in the measurement methods and conditions employed by various research teams. In this study, the total electrical conductivity of an SOFC cathode material was measured by the DC 4-point method by investigating the geometrical parameters of the sample and the measurement terminal and the measurement device using La0.8Sr0.2MnO3+d (LSM). The measurement variables included the spacing between the measurement terminals (1 and 2 cm), lead wire diameter (0.25 and 0.5 mm), specimen thickness (3, 4, and 5 mm), and the applied current (10, 50, and 100 mA). The larger the spacing between the measurement terminal and the thinner the specimen, the smaller the standard deviation.