1. Cabrera Cano, Enrique
May 2014
Assignment Project
M.Sc. Energy Systems, FH Aachen
6/11/2014 7:27 PM 1

2.  Introduction
 Objectives
 Theoretical Background
 Experimental Settings
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Results
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Conclusions
 Appendix
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3.  Membrane electrode assembly (MEA)
 Gaskets and End plates
 Bipolar Plates
6/11/2014 7:27 PM 3
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jülich
GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7

4.  Distribution of gases,
 Prevention of gas leakage,
 Separation of the fuel and oxygen/air,
 Collection of electrical current produced
 Chemical, mechanical and thermal stability
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1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jülich
GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7

5. 5
Nr. Requirement Target Unit
1 Electrical resistivity ˂ 0.01 Ω cm
2 Corrosion resistance ˂ 16 µA/cm²
3 Thermal conductivity ˃ 10 W/mK
4 Compression strength 42 bar
5 Density (Weight/Volume) ˂ 5 g/cm3
6 Costs ˂ 0.0045 US$/cm²
6/11/2014 7:27 PM
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum Jülich GmbH
Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
2. Methta, Vial; Smith, Joyce: Review and analysis of PEM fuel cell design and manufacturing; Journal of Power Sources 114 (2003) 32-53

6.  Introduction
 Objectives
 Theoretical Background
 Experimental Settings
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Results
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Conclusions
 Appendix
66/11/2014 7:27 PM

7. 1. Analysis of Electrical properties of three different
Bipolar plate materials
◦ 70%, 75%, 80% weight percentage of graphite, rest of
polypropylene
2. Influence of the manufacturing process on the
measured material
3. Influence of applied pressure on the total
resistance
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8.  Introduction
 Objectives
 Theoretical Background
 Experimental Settings
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Results
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Conclusions
 Appendix
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9.  Resistance depends on:
I. The type of material
II. The length
III. The thickness
IV. The temperature
 For a given material at
constant temperature
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3. Mc Tavish, J.P.: Foundation Electrical Engineering; Prentice Hall International (UK) Ltd. (1996); ISBN: 0-13-309931-8
𝑹 ∼
𝒍
𝑨

10.  Constant of resistivity (ρ) takes into account the
type of material:
𝑹 = 𝝆
𝒍
𝑨
 Conductivity (σ ) reciprocal of resistivity
𝑮 =
𝟏
𝑹[𝜴]
= 𝑺 𝑮 = 𝝈
𝑨
𝒍
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3. Mc Tavish, J.P.: Foundation Electrical Engineering; Prentice Hall International (UK) Ltd. (1996); ISBN: 0-13-309931-8
4. Maxfield, Clive: Electrical Engineering, Elsevier Inc.,United States of America (2008); ISBN: 978-1-85617-528-9

11.  Pure Graphite 6
◦ Electrical conductivity
◦ Thermal conductivity
◦ sophisticated & costly
processing
◦ unsuitable for reasons of
stability
1. Electro graphite
2. Carbon – carbon composite
3. Sheet Metal
4. Flexible graphite foil
5. Graphite polymer composite 6
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 Proportion between graphite
and polymer 1:
◦ 75% - 80% of graphite
◦ Balance: electrical conductivity and
mechanical stability
1. Bendzulla, Anne: Von der Komponente zum Stack: Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klassen; Forschungszentrum
Jülich GmbH Zentralbibliothek (2010); ISBN: 978-3-89336-634-7
6. Middelman, E.;Kout, W.; Vogelaar, B.;Lenssen, J.; de Waal, E.: Bipolar plates for PEM fuel cells; Journal of Power Sources 118 (2003) 44 – 46

12.  Compression molding
 Injection molding
 Two-component
injection molding
 Preform molding
 Advantages
◦ Automated production,
◦ Short cycle time and
◦ Accurate size
 Disadvantages
◦ Excessive mold wear
◦ Limited size of thickness
ratio and
◦ Could affect conductivity
6/11/2014 7:27 PM 12
6. Middelman, E.;Kout, W.; Vogelaar, B.;Lenssen, J.; de Waal, E.: Bipolar plates for PEM fuel cells; Journal of Power Sources 118 (2003) 44 – 46

13.  Bulk resistance
◦ Ohmic resistance of the
component or material
 Contact resistance
◦ Resistance at the interface of
two different surfaces in contact
with each other
 Total resistance:
◦ Contact resistance + bulk
resistance of the individual
components
6/11/2014 7:27 PM 13
5. Prakash, C. Ghosh; Dey Tapobrata; Singdeo, Debanand: Contact resistance between bipolar plate and gas diffusion layer in high temperature
polymer electrolyte fuel cells; International Journal of Hydrogen Energy 39 (2014) 987-995
𝑹 𝐓𝐎𝐓 = 𝑹 𝟏/𝟐 + 𝑹 𝟐/𝟑 + 𝑹 𝟑 + 𝑹 𝟐 + 𝑹 𝟏

14.  Introduction
 Objectives
 Theoretical Background
 Experimental Settings
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Results
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Conclusions
 Appendix
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15. 25mm
38mm
2.1mm
Thirty samples made from
three different materials
each in equal number
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Two different configurations were designed:
• in-plane and
• through-plane

16.  Two different orientations:
1. in the injection direction
2. perpendicular to the injection direction
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Parameter Value Unit
Current flow area of
injection direction
orientation
0.525 𝑐𝑚2
Current flow area of
perpendicular to injection
direction orientation
0.798 𝑐𝑚2
Electrical Current 0.85 A

17. Sample
Multimiter
Multimiter
Power supply
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VR
I

18. ΔX=2cm
I
a
b
c
I
1 2 3
a = 6.25 mm
b= 12.5 mm
c= 18.75 mm
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19. ΔX=2cm
I
a
b
c
I
4 5 6
a = 9.50 mm
b= 19.00 mm
c= 28.50 mm
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20. Voltage measurement
Current measurement
Beam
Weight
Power supply
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21.  Pressure distribution
analysis
 Parameters
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Parameter Value Unit
Reference measurement
area (45mm*45mm)
20.25 𝑐𝑚2
Sample measurement area
(38mm*25mm)
9.50 𝑐𝑚2
Current 1.00 A

22.  Determination of total force ‘F2’
and pressure from a 5.13kg mass
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𝐹2 = 𝐹0 + 𝑖 ∗ 𝑚 ∗ 𝑔
𝐹2 = 410𝑁 + 32 ∗ 5,13𝑘𝑔 ∗
9.81𝑚
𝑠2
= 2,020.41𝑁
𝑃 =
𝐹
𝐴
=
2,020.41𝑁
0.00095𝑚2
= 2126747.37𝑃𝑎 = 21.27𝑏𝑎𝑟
𝑀1 = 𝑀2
𝐹1 ∗ 𝑥 + 𝑦 = 𝐹2 ∗ 𝑥
𝑖 =
𝐹2
𝐹1
=
𝑥+𝑦
𝑥
=
484𝑚𝑚
15𝑚𝑚
= 32.26
 Ratio of the output force
to the input force (i)

23. 𝑅 𝑇𝑂𝑇 = 𝑅 𝐶𝑃/𝑆𝐹 + 𝑅 𝑆𝐹 + 𝑅 𝑆𝐹/𝐺𝐷𝐿 + 𝑅 𝐺𝐷𝐿 +𝑅 𝐺𝐷𝐿/𝑆 +𝑅 𝑆 +𝑅 𝐺𝐷𝐿/𝑆 +𝑅 𝐺𝐷𝐿 +𝑅 𝑆𝐹/𝐺𝐷𝐿 +𝑅 𝑆𝐹 +𝑅 𝐶𝑃/𝑆𝐹
𝑅 𝑇𝑂𝑇 = 2𝑅 𝐶𝑃/𝑆𝐹 + 2𝑅 𝑆𝐹 + 2𝑅 𝑆𝐹/𝐺𝐷𝐿 + 2𝑅 𝐺𝐷𝐿 +2𝑅 𝐺𝐷𝐿/𝑆 +𝑅 𝑆
As 𝑅 𝐺𝐷𝐿 ≈ 0, it is negligible and hence,
𝑅 𝑇𝑂𝑇 = 2𝑅 𝐶𝑃/𝑆𝐹 + 2𝑅 𝑆𝐹 + 2𝑅 𝑆𝐹/𝐺𝐷𝐿 +2𝑅 𝐺𝐷𝐿/𝑆 +𝑅 𝑆
The following total resistance was determined:
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24. For the reference measurement, the total resistance was determined:
𝑅 𝑇𝑂𝑇,𝑅𝑒𝑓. = 𝑅 𝐶𝑃/𝑆𝐹 + 𝑅 𝑆𝐹 + 𝑅 𝑆𝐹/𝐺𝐷𝐿 + 𝑅 𝐺𝐷𝐿 +𝑅 𝑆𝐹/𝐺𝐷𝐿 +𝑅 𝑆𝐹 +𝑅 𝐶𝑃/𝑆𝐹
𝑅 𝑇𝑂𝑇,𝑅𝑒𝑓. = 2𝑅 𝐶𝑃/𝑆𝐹 + 2𝑅 𝑆𝐹 + 2𝑅 𝑆𝐹/𝐺𝐷𝐿 + 𝑅 𝐺𝐷𝐿
As 𝑅 𝐺𝐷𝐿 ≈ 0, it is negligible and hence,
𝑅 𝑇𝑂𝑇,𝑅𝑒𝑓. = 2𝑅 𝐶𝑃/𝑆𝐹 + 2𝑅 𝑆𝐹 + 2𝑅 𝑆𝐹/𝐺𝐷𝐿
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𝑅 𝑇𝑂𝑇 − 𝑅 𝑇𝑂𝑇,𝑅𝑒𝑓. = 2𝑅 𝐶𝑃/𝑆𝐹 + 2𝑅 𝑆𝐹 + 2𝑅 𝑆𝐹/𝐺𝐷𝐿 +2𝑅 𝐺𝐷𝐿/𝑆 +𝑅 𝑆 − (2𝑅 𝐶𝑃/𝑆𝐹 + 2𝑅 𝑆𝐹 + 2𝑅 𝑆𝐹/𝐺𝐷𝐿)
𝑅 𝑇𝑂𝑇 − 𝑅 𝑇𝑂𝑇,𝑅𝑒𝑓. = 2𝑅 𝐺𝐷𝐿/𝑆 + 𝑅 𝑆
Sample resistance:

25.  Introduction
 Objectives
 Theoretical Background
 Experimental Settings
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Results
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Conclusions
 Appendix
256/11/2014 7:27 PM

26. 0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
30% PP 25% PP 20% PP
InplaneResistivity/Ωcm
Material
Perpendicular to injection
direction
Injection Direction
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27. 0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
30% PP 25% PP 20% PP
InplaneConductivity/S/cm
Material
Perpendicular to injection direction
Injection Direction
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28.  Introduction
 Objectives
 Theoretical Background
 Experimental Settings
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Results
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Conclusions
 Appendix
286/11/2014 7:27 PM

29. 0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
70% graphite-30%PP 75% graphite-25%PP 80% graphite-20%PP
Through-planeResistivity/Ωcm
Materials
4,32
6,44
13,07
21,27
30,02
38,26
[bar]
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30. 0.0000
0.0500
0.1000
0.1500
0.2000
0.2500
0.3000
0.3500
0.4000
70% graphite-30%PP 75% graphite-25%PP 80% graphite-20%PP
Through-planeConductivity/S/cm
Materials
4,32
6,44
13,07
21,27
30,02
38,26
[bar]
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31.  Introduction
 Objectives
 Theoretical Background
 Experimental Settings
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Results
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Conclusions
 Appendix
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32. 1. A change from 70% graphite to 80% graphite
increases all conductivities measured by a factor of
7 approximately
◦ The mechanical properties were not analyzed in this measurement
2. The injection direction orientation shows 18 to
29% higher electrical conductivity than the
perpendicular to injection direction orientation
3. An increase of pressure from 4.32 bar to 38.26 bar
shows an improvement on the total conductivity by
a factor of 2.2 – 2.5
◦ Due to the reduction of contact resistance
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33. 336/11/2014 7:27 PM

34. 1. Bendzulla, Anne: Von der Komponente zum
Stack: Entwicklung und Auslegung von HT-PEFC-
Stacks der 5 kW-Klassen; Forschungszentrum
Jülich GmbH Zentralbibliothek (2010); ISBN: 978-
3-89336-634-7
2. Methta, Vial; Smith, Joyce: Review and analysis of
PEM fuel cell design and manufacturing; Journal
of Power Sources 114 (2003) 32-53
3. Mc Tavish, J.P.: Foundation Electrical Engineering;
Prentice Hall International (UK) Ltd. (1996); ISBN:
0-13-309931-8
6/11/2014 7:27 PM 34

35. 356/11/2014 7:27 PM
4. Maxfield, Clive: Electrical Engineering, Elsevier
Inc.,United States of America (2008); ISBN: 978-
1-85617-528-9
5. Prakash, C. Ghosh; Dey Tapobrata; Singdeo,
Debanand: Contact resistance between bipolar
plate and gas diffusion layer in high temperature
polymer electrolyte fuel cells; International
Journal of Hydrogen Energy 39 (2014) 987-995
6. Middelman, E.;Kout, W.; Vogelaar, B.;Lenssen, J.;
de Waal, E.: Bipolar plates for PEM fuel cells;
Journal of Power Sources 118 (2003) 44 – 46

36.  Introduction
 Objectives
 Theoretical Background
 Experimental Settings
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Results
◦ In-plane resistivity measurement
◦ Through-plane resistivity measurement
 Conclusions
 Appendix
366/11/2014 7:27 PM

37. Nr. Name Weights (kg)
Total Weight
(kg)
Force
“F2” (N)
Pressure Reference
Measurement (bar)
Pressure at
sample surface
(bar)
1. 0 0 0 410.00 2.02 4.32
2. 1 0.643 0.643 611.85 3.02 6.44
3. 2 2.648 2.648 1241.26 6.13 13.07
4. 4 5.13 5.13 2020.41 9.98 21.27
5. 4+2 5.13+2.648 7.778 2851.67 14.08 30.02
6. 4+3 5.13+5.143 10.273 3634.90 17.95 38.26
376/11/2014 7:27 PM

38. Injection Direction Perpendicular to injection direction
Material / Data
Resistivity
(Ωcm)
St.
Dev.
Conductivi
ty (S/cm)
St.
Dev.
Resistivit
y (Ωcm)
St.
Dev.
Conductivi
ty (S/cm)
St.
Dev.
70% graphite-
30%PP 0.901 0.121 1.134 0.188 1.168 0.176 0.880 0.162
75% graphite-
25%PP 0.299 0.040 3.404 0.481 0.385 0.052 2.647 0.388
80% graphite-
20%PP 0.130 0.013 7.742 0.751 0.155 0.022 6.579 0.974
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39. Material 70% graphite-30%PP 75% graphite-25%PP 80% graphite-20%PP
Pressure
(Bar)/Data
Resistivity
(Ωcm) St. Dev.
Resistivity
(Ωcm) St. Dev.
Resistivity
(Ωcm) St. Dev.
4.32 55.18 18.73 30.53 4.64 8.3623 1.3562
6.44 48.10 16.72 26.50 4.27 7.1594 1.0763
13.07 36.21 13.05 19.13 3.10 5.1281 0.6734
21.27 29.93 10.48 15.01 2.21 4.1027 0.5338
30.02 26.91 9.30 13.14 1.84 3.5917 0.4168
38.26 25.04 8.71 12.08 1.65 3.3262 0.3812
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40. Material 70% graphite-30%PP 75% graphite-25%PP 80% graphite-20%PP
Pressure
(Bar)/Data Conductivity (S/cm)
St.
Dev.
Conductivity
(S/cm) St. Dev.
Conductivity
(S/cm)
St.
Dev.
4.32 0.0194 0.0042 0.0335 0.0053 0.1229 0.0217
6.44 0.0224 0.0050 0.0387 0.0063 0.1429 0.0228
13.07 0.0299 0.0070 0.0536 0.0084 0.1983 0.0265
21.27 0.0360 0.0084 0.0680 0.0096 0.2480 0.0347
30.02 0.0400 0.0092 0.0775 0.0104 0.2826 0.0383
38.26 0.0430 0.0098 0.0842 0.0111 0.3045 0.0357
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