(180b) High Performance LT-SOFC Based on a Strontium Iron Cobalt Molybdenum Oxide Based Ceramic Anode Support

High Performance
LT-SOFC Based on a Strontium Iron Cobalt Molybdenum Oxide Based Ceramic Anode
Support

Ke-Ji Pan, Colin
Gore, Lei Wang, Luis Correa, Thomas Langdo, and Bryan Blackburn

Redox Power
Systems, LLC

College Park, MD
20742

Abstract

Solid
Oxide Fuel Cells (SOFCs) consisting of a ceramic anode have several advantages when
compared to a traditional Ni-cermet based anode. The main advantages include
better red-ox cycling stability and chemical stability with the use of hydrocarbon
fuels. However, ceramic materials, such as Nb or La doped SrTiO₃, are
much less conductive than Ni. Furthermore, such materials usually display
appreciable conductivity only after a high temperature reduction step, thus practically
limiting their use to higher operating temperatures. Unfortunately, the
catalytic activity of ceramic anodes is not typically as good as Ni. At low
operating temperatures fuel oxidation kinetics are hindered and must be
improved through the infiltration of catalysts. In addition, ceramic anode-supported
SOFCs have more fabrication difficulties than Ni-cermet cells, such as the
potential for chemical reactions between cell components, thermal mismatch, and
shrinkage mismatch. Therefore, until now there have been very few reports of
ceramic anode-supported LT-SOFCs.

In
this work, we have successfully synthesized new strontium, iron, cobalt,
molybdenum oxide ceramic anode materials with different compositions (SFCM#1-#5) and fabricated anode-supported SOFCs using
GDC as the electrolyte. SFCM displays a conductivity greater than 30 S*cm^-1
between 450 ¡ãC to 650 ¡ãC without the need for a high temperature reduction step,
as shown in Figure 1. Button cells have been fabricated and demonstrated a
power density greater than 0.4 W/cm² at 500 ¡ãC and have shown good
stability in H₂/CH₄ mixtures for several hundred hours.
We have scaled up the size of the cells to greater than 5 cm by 5 cm (Figure 2)
and will discuss additional performance results and future challenges as we
work towards integrating the ceramic anode cells into an LT-SOFC stack.

Figure
1. Conductivities
of various SFCM compositions in 10% H₂ / 90% N₂

Figure
2. Scaled-up
SFCM ceramic anode SOFC.

Key Words: LT-SOFC,
ceramic anode, high performance, long term stability