ANM
2010
3rd
International Conference on Advanced Nano Materials
12-15 September 2010 - Agadir, Morocco
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Abstract
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ANMM115 |
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HIGH-PERFORMANCE
INTERMEDIATE TEMPERATURE SOLID
OXIDE FUEL CELLS (IT-SOFCS) WITH ELECTROLYTE FILMS PREPARED BY
ELECTROPHORETIC DEPOSITION |
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Riccardo
Polini, Francesco Bozza, Enrico Traversa |
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Dipartimento di
Scienze e Tecnologie Chimiche
Università di Roma Tor Vergata, Rome (Italy) |
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Solid
oxide fuel cells (SOFCs) have attracted a considerable attention due to
their high-energy conversion efficiency and fuel flexibility. SOFCs use
ceramic substances as electrolytes and have shown considerable promise
for a variety of applications ranging from mobile devices to stationary
power plants.
A significant boost to the reduction in the manufacturing cost of SOFCs
would be achieved if readily available and easily formed metals, such
as ferritic stainless steels, could be used for the interconnect plate
and gas manifolding. However, the problems of high temperature
corrosion mean this is only realistic if the operating temperature is
reduced to temperatures below 800 °C. A further reduction of
the
operating temperature would also lead to an increase in stack
reliability and lifetime.
To decrease the operating temperature of SOFCs the internal resistance
of the cell must be reduced. This goal can be obtained by using oxygen
ion conductors with superior ionic conductivity values at
600–800
°C. Perovskites with composition La1–xSrxGa1–yMgyO3–δ,
with δ = (x+y)/2, are amongst the most promising
electrolyte materials for IT-SOFCs. IT-SOFCs based on LSGM can be
operated at 750 °C, and even lower operating temperatures could
be
achieved by using thin films of LSGM.
We obtained remarkable power densities for anode-supported solid oxide
fuel cells (SOFCs) based on
La0.8Sr0.2Ga0.8Mg0.2O3-δ
(LSGM)
electrolyte films, fabricated following an original procedure that
allowed avoiding undesired reactions between LSGM and electrode
materials, especially Ni at the anode. Electrophoretic deposition (EPD)
was used for the fabrication of 30 µm-thick electrolyte
films.
Anode supports were made of La0.4Ce0.6O2-x
(LDC). The LSGM powder was
deposited by EPD on an LDC green tape-cast membrane added with carbon
powder, both as pore former and substrate conductivity booster. A
subsequent co-firing step at 1490 °C produced dense electrolyte
films on porous LDC skeletons. Then, a
La0.8Sr0.2Fe0.8Co0.2O3-δ
(LSFC)
cathode was applied by slurry-coating and calcined at 1100 °C.
Finally, the porous LDC layer was impregnated with molten Ni nitrate to
obtain, after calcination at 900 °C, a composite
NiO–LDC
anode. Maximum power densities of 780, 450, 275, 175, and 100
mW/cm² at 700, 650, 600, 550, and 500 °C,
respectively, were
obtained using H2 as fuel and air as oxidant, demonstrating
the success
of the processing strategy. |
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