The goal here is to investigate the feasibility of a
single-step firing process to co-sinter the entire SOFC structure and
reduce the manufacturing cost by an order of magnitude compared to the
existing processes. View an animation of a SOFC.
The processes investigated for obtaining the layers of the SOFC
components include tape casting and screen printing. The process
parameters investigated here include particle size (nano to micrometer
range), shape and their distribution, binder materials and their
amounts, phase distribution in the electrodes, oxygen partial pressure,
heat-up and cool-down profile, hold temperature and time. The range of
process parameters for fabricating the individual SOFC components are
determined, and a common range of parameters are identified to co-sinter
all the layers of the single cell in one firing sequence.
The process is being optimized to (1) lower the processing time,
(2) improve interfacial contact and lower interfacial resistance, (3)
allow graded composite structures for the electrode to lower
polarization as well as internal stresses, and (4) prevent warping in
the structure. The aimed anode-supported SOFC structure consists of
10-40 µm thick dense electrolyte, 50-150 µm thick cathode, and 0.5-2 mm
thick anode.
The objective is to synthesize single cells that have an
operating life greater than 50,000 hours with less than 1% degradation
in electrical performance and a power density greater than 2.0 W/cm2 at
800 C. In the next stage of the program, the process of making these
cells will be automated and undergo scale-up to fabricate multiple
cells.
Our industrial collaborator (BTU
International) will fabricate and assemble fuel cell stacks by
placing interconnects between the anode of one cell and the cathode of
the adjacent cell. They will evaluate these stacks and determine the
scale-up potential to manufacture at a cost not exceeding $500/kWe.
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