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MOLTEN CARBONATE FUEL CELLS ANSALDO FUEL CELLS: Experience & Experimental results Filippo Parodi /Paolo Capobianco (Ansaldo Fuel Cells S.p.A.) Roma, 14th.

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Presentation on theme: "MOLTEN CARBONATE FUEL CELLS ANSALDO FUEL CELLS: Experience & Experimental results Filippo Parodi /Paolo Capobianco (Ansaldo Fuel Cells S.p.A.) Roma, 14th."— Presentation transcript:

1 MOLTEN CARBONATE FUEL CELLS ANSALDO FUEL CELLS: Experience & Experimental results Filippo Parodi /Paolo Capobianco (Ansaldo Fuel Cells S.p.A.) Roma, 14th & 29th March 2007

2 MOLTEN CARBONATE FUEL CELLS ANSALDO FUEL CELLS EXPERIENCE General Content Working principles of Fuel Cells Working principles of Fuel Cells MCFC technology MCFC technology Key components and materials Key components and materials Technological development Technological development LAB level tests LAB level tests Paolo Capobianco (Ansaldo Fuel Cells S.p.A.) Roma, 29 th March 2007

3 Fuel Cells What is a Fuel Cell? It is an electrochemical device that converts energy of a chemical reaction into electricity without any kind of combustion and with high conversion capability. How a Fuel Cell work? It operates like a Battery but it can continuously generate electricity as long as fuel (typically H 2 ) and oxidant (Air) are fed to its electrodes.

4 Battery A generic Battery operation is based on spontaneous Oxidation-Reduction chemical reaction (  G  0), between two materials (f. e. Zn and Cu ++ ) Fuel Cell Fuel cell is a specific kind of Battery based on spontaneous Oxidation-Reduction chemical reaction between two gases Fuel Cells

5 Zn + Cu ++  Zn ++ + Cu + Heat How a Battery works Fuel Cells e e Zn + Cu ++  Zn ++ + Cu + Heat The reaction transfers directly 2 electrons from the Zn atom to the Cu ++ ion. To exploit the “natural tendency” of the Zn atom to deliver 2 electrons to the Cu++ ion so to produce electrical energy, it is necessary to force the 2 electrons to reach the Cu++ through the external circuit (no direct contact of Zn and Cu ++. )

6 Key feature of any electrochemical generator is its suitability to provide the spontaneous oxidation- reduction reaction, but by maintaining separate the two reagents ( Zn and Cu ++ in this example). Electrons current (I) flows from Zn to Cu ++ through an external circuit When  G=0 => I=0 (you have to recharge Battery with an external generator) Fuel Cells

7 Zn Cu Zn ++ SO4 --- Cu ++ SO4 --- Porous Septum Zn  Zn ++ e Anode -Cathode + Cu++  Cu e EaEc e Fuel Cells Daniell Battery Anodic Semireaction Zn  Zn e Cathodic Semireaction Cu  Cu e Total reaction Zn + Cu ++  Zn ++ + Cu Electrolyte

8 How a Fuel Cell works Fuel Cells e e H 2 + 1/2O 2  H 2 O + Heat H2H2 O2O2 The reaction transfers directly 2 electrons from H 2 to O 2. To exploit the “natural tendency” of the H 2 atom to deliver 2 electrons to the O 2 atom so to produce electrical energy, it is necessary to force the 2 electrons to reach O 2 through the external circuit.

9 Key feature of Fuel Cell is its suitability to provide the spontaneous oxidation-reduction reaction, but by maintaining separate the two reagents ( usually H 2 and O 2 ). Electrons current (I) flows from H 2 to O 2 through an external circuit In Fuel Cell you can continuously fed gases (  G  0 => I  0) Fuel Cells

10 The direct conversion of the chemical energy of the Fuel (H 2 ) into electrical energy permits conversion efficiencies significantly higher than by using the conventional processes combustion based Moreover, no combustion means low environmental emissions Fuel Cells

11 Molten Carbonate Fuel Cell (MCFC) ELECTROCHEMICAL REACTION Anodic H 2 + CO 3 --  CO 2 + H 2 O + 2e - Cathodic CO 2 + ½ O 2 + 2e -  CO 3 -- H 2 + ½ O 2  H 2 O + heat + electrical current Operation Temperature T=650 °C

12 ACTIVE POROUS COMPONENTS (Electrolyte) Key components and materials (MCFC)

13 Key materials and components (MCFC) Anode Anode material is not directly involved in gas reaction: It is the catalyst of H 2 oxidation reaction Other requirements for Anode material are chemical (gas and electrolyte) and morphological (high surface area) stability and high electrical conductivity

14 Cathode Cathode material is not directly involved in gas reaction: It is the catalyst of O 2 reduction reaction Other requirements for Cathode material are chemical (gas and electrolyte) and morphological (high surface area) stability and high electrical conductivity Key materials and components (MCFC)

15 Electrolyte Electrolyte material is directly involved in gas reaction Other requirements for Electrolyte material is low ionic resistance and high electronic resistance MCFC electrolyte material is liquid A porous layer (Matrix) is filled by Electrolyte Matrix material must have high chemical stability (gas and Electrolyte) Matrix filled by Electrolyte must avoid direct reaction between H 2 and O 2 Key materials and components (MCFC)

16 Anode: Nickel (Ni-Cr/Al) Nickel is catalyst for H 2 oxidation (no Platinum request: low cost, CO use) Nickel has high chemical stability in MCFC Anode working condition Nickel has high electrical conductivity Nickel is suitable to produce high porosity/high surface area anode Key materials and components (MCFC) Anode section SEM analysis. Pores size is suitable for gas diffusion and electrolyte storage

17 Key materials and components (MCFC) Cathode: Li x Ni (1-x) O Nickel Oxide is catalyst for O 2 reduction Nickel Oxide has good (no total) chemical stability in MCFC working condition Litiated Nickel Oxide has “high” electrical conductivity Nickel Oxide is suitable to produce high porosity/high surface area cathode (typical catalyst bimodal structure) Cathode section SEM analysis. It is possible to see the bimodal structure: larger size pores for gas diffusion, lower size pores for electrolyte storage

18 Key materials and components (MCFC) Electrolyte:Li 2 CO 3 /K 2 CO 3 Liquid Li/K-Na carbonate is an electrolyte solution of Li +, K + (or Na + ), CO 3 -- Liquid Li/K-Na carbonate has low ionic resistance Liquid Li/K-Na carbonate has high electronic resistance Matrix layer is made by LiAlO 2 Chemical stability of LiAlO 2 is very high Electronic resistance of LiAlO 2 is very high Matrix section OM analysis. It is possible to see very low size pores (sub-micron size) for electrolyte storage. Matrix must be totally filled by electrolyte to avoid direct reaction between H 2 and O 2 )

19 Key materials and components (MCFC) METALLIC COMPONENTS

20 Current collector Current collectors have to permit a good gas distribution in the electrodes (anode, cathode) Main requirements for current collector material are chemical stability (gas and electrolyte), good electrical conductivity, good mechanical properties Key materials and components (MCFC)

21 Separator plate Separator plate have to separate each single cells of a stack Main requirements for separator plate material are chemical stability (gas and electrolyte), good electrical conductivity in active area, good mechanical properties Key materials and components (MCFC)

22 ACTIVE AREA (cells current flow through) NO ACTIVE AREA Key materials and components (MCFC)

23 Anode current collector: Ni/AISI310S/Ni Nickel has high chemical stability in MCFC anodic working condition Nickel has low electrical resistivity Mechanical properties of Nickel in MCFC working condition (650 °C) are very poor Trilayer Ni/AISI310S/Ni is used to have good chemical stability and adeguate mechanical properties Key materials and components (MCFC) ACC section OM analysis. It is possible to see AISI310S layer between Ni layers Ni AISI310S

24 Separator plate AISI310S (Active area) AISI310S has good chemical stability in MCFC anodic and cathodic working condition (no direct contact with electrolyte) AISI310S has low electrical resistivity AISI310S corrosion layer has low electrical resistivity Key materials and components (MCFC) Sep.plate section OM analysis (active area). It is possible to see very thin corrosion layers AISI310S

25 Key materials and components (MCFC) Separator plate AISI310S (No active area) AISI310S is protected by Al coating (direct contact with electrolyte) In stack operation Al coating forms Allumina layers very stable in working conditions (gas and electrolyte) Sep.plate section OM analysis.(no active area) It is possible Al coating layer AISI310S AI

26 End first session Key materials and components (MCFC)


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