Characterization of Ni-Infiltrated GDC Electrodes for Solid Oxide Cell Applications

Solid Oxide Cell (SOC) electrodes have been fabricated by infiltration of a porous gadolinia-doped ceria (GDC) scaffold with nickel nano-particles. Interconnected Ni structures were achieved with a conductivity of 620S/cm at 700 degrees C at a Ni content of only 14 wt%. Electrochemical performance in fuel cell mode was evaluated using both two-electrode symmetrical cell and three- electrode fuel cell measurements over a range of temperatures (580-750 degrees C) and hydrogen concentrations (20-80%). At 750 degrees C and in 50%H-2-50%N-2 the area specific resistance was as low as 0.14 Omega.cm(2). The charge transfer activation energy of hydrogen oxidation on these electrodes was similar to 0.53-0.58 eV, lower than that previously reported for conventional Ni-YSZ electrodes. The microstructure of the electrode was studied using Scanning Electron Microscopy. Formation of Ni agglomerates and increased ohmic resistance was observed over approximately 100 hrs of cell operation at 690 degrees C and 50%H-2-50%N-2, though charge transfer resistance was little affected. The results indicate the feasibility of percolated Ni-infiltrated GDC electrodes for future application in SOCs and highlight some of their challenges. (C) 2014 The Electrochemical Society. All rights reserved.