Alternative SOFC Anode Materials with Ion– and Electron–Conducting Backbones for Higher Fuel Utilization

Abstract

Redox-stable anodes are developed for zirconia-based electrolyte-supported solid oxide fuel cells (SOFCs) operating at high fuel utilization, as an alternative to the Ni yttrium-stabilized-zirconia (YSZ) cermet. Gadolinium-doped ceria (GDC, Ce 0.9 Gd 0.1 O 2 ) is utilized as a mixed ionic electronic conductor (MIEC), and combined with lanthanum-doped strontium titanate (LST, Sr 0.9 La 0.1 TiO 3 ) as an electronic conductor. Catalyst nanoparticles (either Ni or Rh) are incorporated via impregnation. The electrochemical characteristics of SOFC single cells using these anodes are characterized in humidified H 2 at 800°C. The stability against redox cycling and under high fuel utilization is analyzed and discussed.

SOFC Anodes Impregnated with Noble Metal Catalyst Nanoparticles for High Fuel Utilization

“…2 (a). In the previous reports, the alternative LST-GDC anodes impregnated with noble metal catalysts showed better tolerance when operating with highly-humidified hydrogen fuel (9,10). Moreover, the anode microstructure changes were analyzed by FIB-SEM and 3-D reconstruction imaging (10).…”

“…Thus, Ni-free stable catalysts should be developed for operation at high fuel utilization. We have already developed alternative SOFC anodes, in which noble metal (Rh, Pt, or Pd) and GDC catalyst particles are dispersed on conducting oxide backbones composed of LST and GDC (9,10). These noble-metal co-impregnated anodes not only exhibit comparable I-V performance to the conventional Ni-cermet anodes, but also have better tolerance against oxidation, i.e.…”

Reversible Solid Oxide Cells: Selection of Fuel Electrode Materials for Improved Performance and Durability

“…The impregnation procedure is also applied to improve the electrochemical characteristics of SOFCs by highly dispersing catalyst particles on a stable backbone structure to provide durability against redox cycling. By using a mixture of LST (La 0.1 Sr 0.9 TiO 3 ) and GDC (Gd 0.1 Ce 0.9 O 2 ) as the fuel electrode backbone and by applying the co-impregnation procedure of Ni and GDC, fuel electrodes with highly dispersed nanoparticles of metallic Ni catalysts and GDC, denoted as Ni-GDC/LST-GDC, can be fabricated (7)(8)(9).…”