Chemical bulk diffusion and electrochemical properties of SmBa0.6Sr0.4Co2O5+δ cathode for intermediate solid oxide fuel cells

In this work, the chemical bulk diffusion coefficient (Dchem) of SmBa0.6Sr0.4Co2O5+δ was determined by an electrical conductivity relaxation (ECR) method. The equation of Dchem as a function of temperature in the range of 500–700 °C exhibits as follows: = 1.77×10−5 (−68.039 (kJ mol−1)/RT) (m2s−1) ochemical impedance spectroscopy (EIS) technique was performed over the temperature range of 600–850 °C to determine the cathode polarization resistance (Rp). The area specific resistances (ASR) of SmBa0.6Sr0.4Co2O5+δ-Ce0.8Sm0.2O1.9 (70:30 in wt%) composite cathode were 5.16, 0.86 and 0.21 Ω cm2 at the operating temperatures of 600, 700 and 800 °C respectively. The exchange current densities (io) for oxygen reduction reaction (ORR) were determined from the EIS approach, and low-field and high-field cyclic voltammetry. The activation energies (Ea) of ORR determined from the slope of Arrhenius plots for EIS, low-field and high-field technique were 148.6, 69.8 and 74.2 kJ mol−1, respectively. Based on the electrochemical properties, the mixed-ionic-and-electronic conductor (MIEC) of SmBa0.6Sr0.4Co2O5+δ is a potential cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) based on a SDC electrolyte.