Decreasing the polarization resistance of LaSrCoO4 cathode by Fe substitution for Ba(Zr0.1Ce0.7Y0.2)O3 based protonic ceramic fuel cells

Abstract

LaSrCo1−xFexO4−δ layered perovskites with K2NiF4 structure were synthesized successfully via the Pechini method and evaluated as cathode material for Ba(Zr0.1Ce0.7Y0.2)O3 (BCZY) electrolyte supported protonic ceramic fuel cells (PCFCs). X-ray diffraction results show that LaSrCo1−xFexO4−δ (0.0 ≤ x ≤ 0.5) were all single phase with K2NiF4 structure. Thermal expansion coefficient of LaSrCo0.5Fe0.5O4−δ is close to that of BCZY electrolyte. The conductivity of LaSrCo0.5Fe0.5O4−δ in air is 142 S cm−1 at 750 °C. At 750 °C, the Rp of LaSrCo0.5Fe0.5O4−δ is measured and the value is about 0.12 Ω cm2. The main rate-determining step in LaSrCo0.5Fe0.5O4−δ cathode is the dissociation of adsorbed oxygen molecules into atoms on the surface. Further, cathodic overpotential of 90 mV is obtained for LaSrCo0.5Fe0.5O4−δ cathode at current density of 0.2 A cm−2 at 750 °C. The substitution of Co by Fe causes an enhancement of the better electrochemical properties implying that LaSrCo0.5Fe0.5O4−δ could be applied as possible cathode for PCFCs.