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Ceramic nanocomposites in solid oxide fuel cells (SOFC)

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Ceramic nanocomposites in solid oxide fuel cells (SOFC) like YSZ, CeO2 (ceria)-SDC used as electrolytes, anodes and cathodes.
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Ceramic nanocomposites in solid oxide fuel cells Term paper presentation for the course of Composite Materials Metallurgical and Materials Engineering IIT Kharagpur
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Page 1: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

Ceramic nanocomposites in solid oxide fuel cells

Term paper presentation for the course of

Composite Materials

Metallurgical and Materials Engineering

IIT Kharagpur

Page 2: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

SOLID OXIDE FUEL CELLS

• Electrolyte is in solid state• Anode reaction:

H2 + O2- H2O + 2e-

• Cathode reaction:

1/2 O2+ 2e-O2-

overall reaction:H2 + 1/2 O2 H2O

Advantages:• High energy efficiency and low

emission• No need for precious metal• High tolerance to impurities

Page 3: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

SOFC COMPONENTS

Challenges:•High temperature: YSZ based SOFC has an operating temperature of 1000C•Utilization of H2: High production cost

Page 4: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

LOWERING OPERATION TEMPERATURE: COMPOSITE ELECTROLYTES

A composite electrolyte is a multiphase membrane made of two or more components to achieve an enhancement of the overall ionic conductivity

conductivities of SDC–(Li 0.435 Na 0.315 K

0.25 )2 CO3 composite

electrolytes

(□) SDC (samarium doped ceria)(○) SDC–10 wt.% carbonate(Δ) SDC–30 wt.% carbonate(∇) SDC–50 wt.% carbonate

LTSOFC (300-600C) can be achieved with nanocomposite materials

Page 5: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

SDC-Na2Co3 ELECTROLYTE

• core–shell nanocomposite material prepared by coprecipitation

• SDC core and amorphous Na2CO3 shell in nanoscale

• applied as electrolyte in low-temperature SOFC

• Peaks observed for CeO2• Peaks absent for Na2CO3

Faceted irregular shaped particles <100nm

Page 6: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

SDC-Na2Co3 ELECTROLYTE

(a): TEM imageuniform Na2CO3 thin layer of 4–6 nm

(b): HRTEM imageCore and shell interface.

Na2CO3  layer (4–6 nm)

Page 7: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

SDC-Na2Co3 ELECTROLYTE

Page 8: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

SDC-Na2Co3 ELECTROLYTE

• H+conductivity is 1–2 orders of magnitude higher than the O2− conductivity.

• Amorphous nature of Na2CO3 provides disorder at high temperature facilitating higher charge transfer.

simultaneous H+ and O2− conduction @ 300 oC

Page 9: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

DUAL ION CONDUCTION

• The interface supplies high conductive path for proton

• Oxygen ions transported through SDC grain interiors.

Page 10: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

MULTI-ION FLOW

Page 11: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

NANOCOMPOSITE ELECTRODES

Function of anode :

1.Catalyse electrochemical oxidation of fuel

2.transfer the released charges to a current collector.

These electrode reactions can only occur at the oxide-ion conductor/electronic conductor/gas three-phase boundary (TPB)

Page 12: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

CuZn-NSDC ANODE

• fine particle size distribution (50–100 nm)

• adequate porosity• well-connected Cu

and Zn.• Enhanced

electronic conductivity.

• SDC-Na2CO3 as main oxygen ion conductor.

Page 13: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

CuZn-NSDC ANODE

Hexagonal Zn (10 nm)

Hexagonal Zn atoms mixed with 5 nm Cu particles.

Interconnected anode structure enhances diffusion.

Page 14: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

CONCLUSIONS

• Use of SOFCS at low temperatures is possible with nanocomposite materials which provide higher conduction.

• for commercialization of this environment friendly technology, development of cheaper materials for electrolyte and electrode is imperative.

• Use of crude hydrocarbon fuel is possible with SDC-carbonate.

Page 15: Ceramic nanocomposites in solid oxide fuel cells (SOFC)

REFERENCES

• Rizwan Raza , Xiaodi Wang, Ying Ma, Bin Zhu, A nanostructure anode (Cu0.2Zn0.8) for low-temperature solid oxide fuel cell at 400–600 °C, Journal of Power Sources,Volume 195, Issue 24, 15 December 2010, Pages 8067–8070

• Xiaodi Wanga, Ying Maa, Shanghua Li a, Abdel-Hady Kashyoutb, Bin Zhuc, Mamoun Muhammeda, Ceria-based nanocomposite with simultaneous proton and oxygen ion conductivity for low-temperature solid oxide fuel cells, Journal of Power Sources 196 (2011) 2754–2758

• Xiaodi Wang, Ying Mab, Rizwan Raza, Mamoun Muhammed, Bin Zhu, Novel core–shell SDC/amorphous Na2CO3 nanocomposite electrolyte for low-temperature SOFCs, Electrochemistry Communications 10 (2008) 1617–1620

• Yicheng Zhao, Chun Xia, Lijun Jia, Zhiming Wang, Hongjiao Li, Jinshuai Yu, Yongdan Li*, Recent progress on solid oxide fuel cell: Lowering temperature and utilizing non-hydrogen fuels, international journal of hydrogen energy xxx (2013) 1-20


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