Effect of Ni content on the microstructure and electrochemical properties of Ni–SDC anodes for IT-SOFC

Ni–SDC (samaria-doped ceria) films for an IT-SOFC anode were fabricated by a slurry spin coating method. The microstructure and electrochemical performances of the Ni–SDC anodes were investigated with respect to the Ni vol.%. The connectivity of Ni–Ni grains, SDC–SDC grains and Ni–SDC grains, which is remarkably influenced by the Ni vol.%, is suggested to dominate the electrochemical behavior of the Ni–SDC anodes, including a hydrogen adsorption/diffusion process on the surface of Ni particles and a charge transfer process on the SDC electrolyte. A porous microstructure consisting of homogeneously distributed Ni and SDC phases together with well-connected grains was observed for the Ni–SDC anodes containing 50% and 60% volume content of Ni, which exhibited a polarization resistance around 0.1 Ω cm2 together with an overpotential around 30 mV under a current density of 200 mA cm− 2 at 800 °C in a 60%N2 + 40%H2 atmosphere.