(65b) Redox Stable Conductivity of B-Site Doped SrTiO3 for SOFC Anodes
AIChE Annual Meeting
2009
2009 Annual Meeting
Education
Student Poster Session: Materials Engineering and Sciences
Monday, November 9, 2009 - 8:30am to 11:00am
The stability of solid oxide fuel cell (SOFC) anodes during
cycles of reducing and oxidizing environments (redox cycling) is a critical
parameter of durability, particularly for portable applications. The standard
Ni-YSZ anode is not stable during redox cycles because the volume of Ni
substantially increases upon oxidation. This expansion ultimately results in
mechanical failure of the fuel cell. To address this limitation, SrTaxTi1-xO3
(STT) has been investigated as a potential material for redox-stable anodes.
While Ni is both an e- conductor and an oxidation catalyst, STT can
only provide e- conduction and a separate catalyst must be added.
Dense STT and porous STT-YSZ composites, for x = 0.01, 0.05, and 0.10, were
sintered in both air at 1873 K and hydrogen at 1773 K. X-ray diffraction (XRD)
indicated a single perovskite phase for STT and that STT and YSZ are chemically
compatible. Conductivities greater than 1 S·cm-1 were achieved for
porous STT-YSZ with x = 0.01 and 0.05 when initially reduced at 1773 K. Without
this high temperature reduction, conductivity was too low for SOFC anode
applications. STT with x = 0.01 demonstrated the highest redox stable
conductivity with a porous conductivity of 0.9 S·cm-1 after
oxidation at 1273 K.