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

摘要

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 cm~2 together with an overpotential around 30 mV under a current density of 200 mA cm~(-2) at 800 °C in a 60%N_2 + 40%H_2 atmosphere.