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 (Ce 0.9 Gd 0.1 O 2 ) is utilized as a mixed ionic-electronic conductor (MIEC), and combined with LST (Sr 0.9 La 0.1 TiO 3 ) 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 H 2 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.