Alternative Ni-Impregnated Mixed Ionic-Electronic Conducting Anode for SOFC Operation at High Fuel Utilization

Abstract

Redox-stable anodes are developed for zirconia-based electrolyte-supported SOFCs in order to improve the durability against fuel supply interruption and for higher fuel utilization, as an alternative to the conventional Ni-YSZ cermet. GDC (Ce0.9Gd0.1O2) is utilized as a mixed ionic-electronic conductor (MIEC), and combined with LST (Sr0.9La0.1TiO3) as an electronic conductor. Ni catalyst nanoparticles are incorporated via impregnation. The electrochemical characteristics of SOFC single cells using these anode materials are investigated in humidified H2 at 800°C. The stability against redox cycling and under high fuel utilization is analyzed and discussed. Ni-impregnated anodes with dispersed Ni catalyst nanoparticles on conducting oxide LST-GDC backbones exhibit lower anode non-ohmic overvoltage, and improve I-V performance. These anodes also show better redox stability compared to conventional anodes because of the isolation of Ni catalysts, preventing their agglomeration. Moreover, the co-impregnation of Ni catalysts and GDC nanoparticles further improves electrochemical characteristics due to a decrease in anode ohmic (IR) loss and non-ohmic overvoltage. This anode shows comparable I-V performance to conventional anodes for typical humidified hydrogen fuels, and is a promising redox-stable alternative for application at high fuel utilization.