Electrochemical Performance of La1.5Sr0.5Ni1-xFexO4+δ Cathode for IT-SOFCs

- Fe-doping reduces polarization resistance of La1.5Sr0.5Ni1-xFexO4+δ (LSNF) cathode.
- Single cell performances with LSNF electrode are highly improved by Fe-doping.
- Molecular oxygen dissociation and charge transfer process control cathode reaction.

La1.5Sr0.5Ni1-xFexO4+δ (LSNF, x = 0, 0.3, 0.5) series materials are synthesized as potential cathode materials for intermediate-temperature solid fuel cells by an EDTA-citrate complexation process. The effects of Fe substitution for Ni on the structure, transport property and electrochemical performances are investigated. X-ray diffraction shows that all samples with Fe-doping are identified as single phase materials with a tetragonal I4/mmm space group. Fe-doping decreases electrical conductivity of La1.5Sr0.5Ni1-xFexO4+δ. The study of symmetrical cells with La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) as an electrolyte shows a decreasing tendency of polarization resistance (Rp) of La1.5Sr0.5Ni1-xFexO4+δ with increasing Fe content. The impedance data at different oxygen partial pressures reveal that the electrode reaction is controlled by the molecular oxygen dissociation and charge transfer processes. The substitution of Fe improves the electrode kinetics and enhances the electrochemical performance of LSNF electrode significantly. The LSGM electrolyte (400 μm) supported single cell with La1.5Sr0.5Ni0.5Fe0.5O4+δ as cathode and Ni-Gd0.1Ce0.9O2-δ as anode delivers relatively high power density of 282 mW cm−2 at 800 °C.