nickel-free hybrid metal-ceramic supported sofc r. costa · generations of planar sofcs dlr.de •...

Nickel-free Hybrid Metal-Ceramic Supported SOFC R. Costa remi.costa@dlr.de

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 1

Alantum Europe GmbH: R. Poss, ARMINES: A. Chesnaud, F Willot CerPoTech: G. Syvertsen, CNR: M. Viviani, A. Sanson

Grenoble INP: L. Dessemond Ceraco GmbH: R. Semerad Saan Energi: A. Ansar

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 2

Aeronautics Space Transport Energy Space Agency Project Management Agency

Research Institution

DLR German Aerospace Center

Cologne

Oberpfaffenhofen

Braunschweig

Goettingen

Berlin

Bonn

Neustrelitz

Weilheim

Bremen Trauen

Lampoldshausen

Stuttgart

Stade

Augsburg

Hamburg

Juelich > 7500 employees across 32 institutes and facilities at 16+1 sites.

Offices in Brussels, Paris, Washington.

Generations of planar SOFCs > ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 3

1st gen.

2nd gen.

3rd gen.

ESC

Limited power density Fuel flexibility Robustness

Stationary Transportation

High power density Fuel flexibility

Sulfur poisoning Thermal cycling Redox Cycling

Stationary Transportation

High power density Fuel flexibility

Sulfur poisoning Thermal cycling Redox Cycling

Stationary Transportation

ASC

MSC

Electrolyte

Cathode

Anode

30 µm

25 µm

35 µm Bipolar plate

Bipolar plate

porous metallic substrateanodeelectrolyte

contact layercathode current collectorcathode active layer

protective coating

not used airoxygen/air

air channel

fuel channel

fuel brazing not used fuel + H O2

(not in scale)

Plasma Deposition Technology

Ferritic Substrates and Interconnects

Compact Design with Thin Metal Sheet Substrates

Brazing, Welding and Glass Seal as Joining and Sealing Technology

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 4

3rd Gen. SOFC: MSCs at DLR

Vortrag > Autor > Dokumentname > Datum

MSC Cell 12.5 cm² cell at 800°C; H2/N2 and air

10 Cells Stack 100 cm² single cells at 800°C; H2/N2; air

MSC-10-31, 800°C, 27h10H2+10N2/ 20 Luft (SLPM)

P1: Kennlinie nach Aufheizen, KL1

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

1,1

1,2

0 100 200 300 400 500Stromdichte i [mA/cm²]

Zells

pann

ung

U [V

]

0

200

400

600

800

Leis

tung

sdic

hte

p [m

W/c

m²]

OCVZelle 10: 1,019 VZelle 9: 1,006 VZelle 8: 1,007 VZelle 7: 1,001 VZelle 6: 1,006 VZelle 5: 1,016 VZelle 4: 1,022 VZelle 3: 1,005VZelle 2: 1,013VZelle 1: 1,014 V

@ 7,0 VPstack = 250 WFU = 24,8 mol%

p

U

Stromdichte@ 700mVZelle 10: 173 mW/cm²Zelle 9: 315Zelle 8: 324Zelle 7: 325 mW/cm²Zelle 6: 318Zelle 5: 324 mW/cm²Zelle 4: 329Zelle 3: 320 mW/cm²Zelle 2: 319Zelle 1: 320 mW/cm²

3rd Gen. SOFC: MSCs at DLR > ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 5

0,6

0,7

0,8

0,9

1

1,1

0 400 800 1200 1600

Current density / mA*cm-2

Cel

l vol

tage

/

V

0

250

500

750

1000Po

wer

den

sity

/

m

W*c

m-2

A BC D

APS

SPPS

• P. Szabo, J. Arnold, T. Franco, M. Gindrat, A. Refke, A. Zagst, A. Ansar, ECS Transactions, 2009 (25) 2 p.175-185

• D. Soysal, A. Ansar, Z. Ilhan, R. Costa, ECS transactions, 2011 (35) 1 p.2233-2241

Issues to be adressed for improving MSCs

• Cr-poisoning at the cathode side > Protective coating required • Improve tolerance toward sulfur poisoning

• Life time of metal substrate if stationary applications are considered

• Hermitic electrolyte

Beyond the 3rd Gen. SOFC:

Which materials and architecture for the next generation of SO(F)C?

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 6

Metallic alloy foam (such as FeCrAlY), capable of forming alumina protective scale Excellent mechanical properties, but high sensitivity to chemical reactions (high degradation)

Oxidized metal alloy foam, with stable aluminum oxide scale Excellent mechanical properties and stable oxide scale to protect against chemical reactions (low degradation), but poor or no electronic conductivity

Anodization

Metal substrate resistant toward oxidation

Al rich alloys, on the basis of MCrAl(Y) with M being Fe, Ni, Co or a mixture

Formation of an Al2O3 layer as a durable protective coating

Nickel-free Hybrid Metal-Ceramic Supported SOFC

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 7

Impregnation

Anode current collector - Oxidized alloy foam with impregnated conductive ceramic (LSCM or LST). Excellent mechanical properties and stable oxide scale to protect against chemical reactions (low degradation), high electronic (and ionic) conductivity

Roughness Adjustment

Smooth current collector Low roughness surface ready for coating of functional layers of cell

Hybrid current collector mechanically and chemically stable in both oxidant and reducing atmosphere

Infiltration with an electronic conductor (ideally a ceramic)

Target : 100 S/cm

Dense La0.1Sr0.9TiO3 (800°C): - sintering in H2: σtot ≈ 150 S/cm O. Marina et al. Solid State Ionics, 149 (2002) 21-28. S. Hashimoto et al. Journal of Alloys and Compounds, 397 (2005) 245-249. Y. Tsvetkova et al. Materials and Design, 30 (2009) 206-209.

Nickel-free Hybrid Metal-Ceramic Supported SOFC

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 8

Fabrication of functional layers on top of anode current collector+ infiltration

Realization of Evolve Cell LSCF-CGO cathode CGO diffusion barrier layer YSZ or ScSZ Electrolyte LSCM-CGO anode (with infiltrated Ni)

Use of perovskite materials at the anode

and cathode, being modified by addition of

suitable catalysts

High power density, Sulfur resistant, Fuel flexibility, Thermal cycling, Redox Cycling

Stationary applications …

Nickel-free Hybrid Metal-Ceramic Supported SOFC

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 9

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 10

Composition of the anode: Ce1-xGdxO2-α / La0,1Sr0,9TiO3-α Electrolyte: 8-YSZ Cathode : Ce1-xGdxO2-α / La0,4Sr0,6Co0,2Fe0,8O3-α

Nickel-free Hybrid Metal-Ceramic Supported SOFC

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 11

Development strategy

1cm² 15-20 cm² 100 cm²

- Reactivity tests - Conductivity measurement - Understanding the behaviour

- Shaping strategy - Prototype - Testing and optimization

- upscaling

(CNR ISTEC)

(DLR)

10mm

10mm

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 12

Evaluation of the anodic electrocatalyst

• Symetrical cells tested in 3-electrodes configuration

• Experimental conditions Gas composition, gas flow, Temperature • Elaboration parameters Composition, Thickness porosity

RE

WE

CE

Φ = 16 mm

≈ 2 mm

anode

YSZ

Au grids Au wire

Au wire

Au wire

alumina

P

Evaluation of the electrocatalyst > ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 13

Rpol decreases: increase in thickness and/or decrease of the pore size

Electrokinetic modeling • Reaction mechanism and kinetic data • Thermodynamic data

⇒ detailed multistep (electro-)chemical mechanism

⇒ thermodynamically consistent kinetic modeling

⇒ evaluation of main performance limitation processes

R1:

R2:

R3:

R4:

C1:

C2:

Evaluation of the electrocatalyst > ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 14

97 % H2, 3% H2O, OCV LST-CGO20, 50 vol%-50 vol % screen printing Data - Anode: 15 μm - Electrolyte: 925 μm - Mesh: 700 μm - Inlet: 50 mL/min/cm2

- Active surface area: 4.6 104 m2/m3

⇒ - qualitative agreement between modeling and experiments

- three main impedance features

Electrochemical results: IST20

Evaluation of the electrocatalyst > ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 15

interfacial charge transfer

⇒ - unambiguous assignment of impedance features

- influence of surface chemistry

Efficient LST based anodes requires high specific surface area

surface charge transfer

97 % H2, 3 % H2O, OCV

Evaluation of the electrocatalyst > ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 16

Solid line: full model Dashed line: reduced to 1D ⇒ ideal supply channel transport Dashed-dotted line: reduced to 1D with CDL = 0

H2O dissociation

gas conversion impedance

⇒ - separation of transport and chemistry

- cell design optimization

Evaluation of the electrocatalyst > ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 17

V. Yurkiv, G. Constantin, A. Hornes, A. Gondolini, E. Mercadelli, A. Sanson, L. Dessemond, R. Costa, submitted to Journal of Power Sources

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 18

Evaluation of the current collector

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 19

0

2 0 0

4 0 0

6 0 0

8 0 0

0 . 0 1

0 . 1

1

0 1 0 0 2 0 0 3 0 0

H 2

Tem

pera

ture

(°C

)

Time (hour)

Tota

l con

duct

ivity

(S/c

m)

Evaluation of the current collector

Reduction at 750 °C under H2

Total conductivity << 100 S/cm

LST-NiCrAl current collector > Cathode sintering leads to full reoxidation of LST Evaluation of in-situ reduction of LST during stack sealing/commissioning

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 20

0

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

0 2 0 4 0 6 0

H 2 H 2 A i r A i r H 2

Tem

pera

ture

(°C

)

Tota

l con

duct

ivity

(S/c

m)

1

10

0.1

0.01

0.001

Evaluation of the current collector

Total conductivity << 100 S/cm

Reduction at 900 °C under H2

LST-NiCrAl current collector > Cathode sintering leads to full reoxidation of LST Evaluation of in-situ reduction of LST during stack sealing/commissioning

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 21

Full Cell Processing

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 22

First demo Prototype through Plasma Spraying Route

100µm thick electrolyte

Cathode

Co-pressed LST-CGO infiltrated NiCrAl foam

OCV for 140h

At 180mA for 180h

Low risk approach using the know how from DLR for spraying YSZ layers. No need of sintering step.

0

0.2

0.4

0.6

0.8

1.0

1.2

0 10 20 30 40 50 0

5

10

15

i / 10-3 A.cm-2

pote

ntai

l / V

pow

er d

ensi

ty /

mW

.cm

-2

H2/N2, 62 mL/min/cm2

Cell S1, 769°C

0

0.2

0.4

0.6

0.8

1.0

1.2

0 10 20 30 40 0

5

10

15

20

i / 10-3 A.cm-2

pote

ntai

l / V

pow

er d

ensi

ty /

mW

.cm

-2

H2/N2, 62 mL/min/cm2

Cell S2, 764°C

⇒ - stable OCV and polarization

curves for 50 hours

- 10-15 mW.cm-2 at 0.7 V in H2-air

- leakage (OCVexp < OCVNernst)

4 3 2 1 0

-1 -2

5 6 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

H2, 62 mL/min/cm2

Re(Z) / Ω.cm2 - Im

(Z) /

Ω.c

m2

Cell S1, OCV = 0.98 V before, 769°C after, 794°C

2 1 0

-2 -1

3 2 1

0 -1 -2 4

8

3 2

7

4

Prototype > ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 23

towards thin films electrolyte

Current collector

Active Anode

Nanostructured YSZ Buffer layer

CGO Layer

3µm

Active anode

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 DLR.de • Chart 24

2

1

0

-1

H2/N2, 62 mL/min/cm2

12 13 14 15 16 17 18 Re(Z) / Ω.cm2 - I

m(Z

) / Ω

.cm

2

Cell P1, 793°C, OCV = 0.4 V

4 3

2 1 0

-2 -1

Cell P: - low OCV

- no polarization curves

- high Rs but low Rpol

4

2

0

-2

H2/N2, 62 mL/min/cm2 before, 764°C after, 771°C

Cell S2, OCV = 1.03 V

- Im

(Z) /

Ω.c

m2 3

4

2 1

0 -1 -2 3 1 0

-2 4

2

-1

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Re(Z) / Ω.cm2

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015

towards thin film electrolytes 25

• La0,1Sr0,9TiO3-α Requires high specific surface area

Requires specific treatment for full activation

• Reducibility and maximum level of perovskites electrocatalysts needs to be enhanced

• Implementation of metals seems necessary to achieve conductivity target in the current collector

> demonstration up to 100cm² cell of SOC

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 26

Conclusion & perspectives

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 27

Acknowledgement FCH JU for funding under the grant Agreement n°303429

F. Han (for coatings), V. Yurkiv (modelling), G. Schiller, Prof. K.A. Friedrich,

Thank you for your attention!

> ICACC15 > R.Costa • Ni-free Hybrid Metal-Ceramic Supported SOFC > 29. January 2015 28