Advanced Diagnostics Tools and AnalysisMethodologies in Solid Oxide Fuel Cells

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24. June 2009 J. Malzbender, P. Batfalsky, L. Blum, S. M. Groß, V.A.C. Haanappel, N. H. Menzler, A. Neumann, V. Shemet, R.W. Steinbrech, I.C. Vinke

International Symposium on

Diagnostics Tools for Fuel Cell

Technologies, Trondheim 2009

24. June 2009 Folie 2

� Role of “Advanced Diagnostics Tools and

Methodologies”

� Post operation methodology

� Post operational analysis methods

� Post operation analysis procedure

� Example G-Design stack

� Improved design

24. June 2009 Folie 3

Role of “Advanced Diagnostics Tools and Methodologies”

Fabrication

Design

Post Operation

Analyses

Operation

Light weight stack (APU application)

Short stack for SOFC development

F-design

CS-design

Diagnostics Tools / Methodologies

Advanced characterization

methods are an essential

element to understand the stack

performance within the frame-work of a systematic testing

24. June 2009 Folie 4

� Disassembling with selected experts depending on expected degradation

mechanism. Experience in synthesis, production, interaction, thermo-

mechanics, corrosion, thermo-chemistry, sealants, stack / system

operation, single cell testing, microscopy, SEM

� 108 dissections from 8.2002 to 9.2008.

� Electro-chemical results and irregular events are considered.

� A digital photographic image is taken of every stack plane.

� Unusual observations are investigated microscopically during

disassembling.

� After dismantling more detailed SEM (TEM) investigation are carried out.

� Every stack opening is discussed in a subsequent meeting, suggesting

further detailed follow up work.

� Reports are passed on to selected members of the SOFC development

team.

� Selected results are presented to the entire SOFC team in semi-annual

meetings.

Post Operation Methodologie

24. June 2009 Folie 5

Materialography & Image analysis Macroscopic changes, color

SEM and EDX Microscopic / structural changes,

qualitative chemical analysis,

Wet chemical analysis quantitative, coarse localized

SIMS quantitative, localized

Thermography, computer tomography short circuit localization, porosity

XRD structural changes

TEM local changes, interfaces, reactions

Leakage, liquid dye inspection localization of leakages

Post Operational Analysis Methods

24. June 2009 Folie 6

Post operation analysis procedure

Example G-Design stack (G1002-04)

Investigation of degradation and failure by comparison of electrochemical

results with stack dismantling results

low power output

G-Design problems :

high degradation rate

0 200 400 600 800 1000 1200 1400

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

0,0

0,2

0,4

0,6

0,8

1,0

1,2

Alterung 23.0 ± 0.1%

in 1000 Stunden

über 314 Stunden

Alterung 35.3 ± 0.1%

in 1000 Stundenüber 644 Stunden

Alterung 37.0 ± 0.3%

in 1000 Stunden

über 299 Stunden

Alterung 10.4 ± 0.1%

in 1000 Stunden

über 803 Stunden

Leck in d

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Da

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Spa

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/ V

Zeit / h

Stro

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/ A/c

m2

24. June 2009 Folie 7

Before further dismantling took place the origin of the short circuiting was

investigated using infrared camera imaging (thermography).

Ceramic glue shows partly red coloring and bubbles.

In addition a short circuiting to the next cassette was detected.

Sealing of cell: ceramic glue

Sealing to next layer: glass-

ceramic

24. June 2009 Folie 8

D5

Origin of the short circuiting was a deformation

of the manifold.

Mechanically damaged contact layer

24. June 2009 Folie 9

Cathode side

~ 3,5 - 4 mm

~ 0,2 – 0,3 mm

Small contact width compared to standard design

Stack G1002-3

Standard F2060-1

Air channel

Air channel

Contact

Contact

Air channel

Trace of the contact

width

Origin of low power output

24. June 2009 Folie 10

Edge of the cell near the sealant

6031.6O

Cr2O31004068.4Cr K

FormComp.

%

Atom

%

Mass

%

Element

Formation of Cr2O3 on the electrolyte

High degradation rate

24. June 2009 Folie 11

55.621.2O

La2O341.310.735.2La L

CuO3.51.82.8Cu KCoO1.20.690.97Co K

MnO32.819.525.4Mn K

Cr2O321.311.814.5Cr K

FormComp.

%

Atom

%

Mass

%

Element

Modified contact layerEinbettmasse

Einbett

masse

LCC10

New phases

MnOx

Crofer22 APU first

High degradation rate

24. June 2009 Folie 12

61.323.0O

La2O323.76.220.2La L

ZrO250.917.637.7Zr L

MnO18.911.314.6Mn K

Cr2O36.53.74.5Cr K

FormComp.

%

Atom

%

Mass

%

Element

Chromia composites near the three

phase boundary

High degradation rate

24. June 2009 Folie 13

Problem:

� Short circuit due to local upwards bending

of the manifold (creep effect)

� Cr2O3 reaction products (from gas phase)

were detected on the surface of the

electrolyte

� New reaction products were detected in

the contact layer (influence of the ceramic

glue)

� Chromia composites were found near the

three-phase boundary which might be

associated with the high degradation

Solution:

� Application glass-ceramic support

point

� Substitution of ceramic glue by glass

– ceramic sealant

� Components of the ceramic glue

could be confirmed, a follow up stack in

the same design with glass – ceramic

sealant had a degradation of (2,6-2,8)%

/ 1000h compared to (23-35%).

24. June 2009 Folie 14

Cracks in cell, green color suggests re-oxidation

Application point of glass-ceramic support point

Manifold bend

towards anode side Manifold bend

towards anode sideApplication point of glass-

ceramic support point

24. June 2009 Folie 15

Cut

Air inlet Air outlet

Large manifold made from thin metal

sheets is not geometrically stable at

high temperatures

Results are short circuit or cell

fracture

24. June 2009 Folie 16

Improved Design

Using a combination of

metallic and glass-ceramic

sealants.

Significantly reduced size of

unsupported manifold.

In addition asymmetric cell

to permit smaller in-plane

gradient on thermal cycling.

24. June 2009 Folie 17

Stack-Dismantling

Jürgen Malzbender

Vincent Haanappel

Norbert Menzler

Peter Batfalsky

Rolf Steinbrech

Ico Vinke

Thank you for your attention