Characterization of Water Management in PEM Fuel Cells with - - PowerPoint PPT Presentation

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Characterization of Water Management in PEM Fuel Cells with - - PowerPoint PPT Presentation

May 31, 2023 411 likes •625 views

Characterization of Water Management in PEM Fuel Cells with Microporous Layer Using Electrochemical Impedance Spectroscopy Dzmity Malevich, Ela Halliop, Kunal Karan, Brant A Peppley and Jon Pharoah WWW.FCRC.CA Water management in PEM fuel cell

slide-1
SLIDE 1

WWW.FCRC.CA

Characterization of Water Management in PEM Fuel Cells with Microporous Layer Using Electrochemical Impedance Spectroscopy

Dzmity Malevich, Ela Halliop, Kunal Karan, Brant A Peppley and Jon Pharoah

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SLIDE 2

Water management in PEM fuel cell

Hydrogen Oxygen Water Hydrogen + + + + Oxygen Water

membrane catalyst porous transport layer

e e + + + +

e e

+ + + +

e e

water content

Flooded Dry

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SLIDE 3

Microporous Layer (MPL)

2

porous carbon backing microporous layer catalyst layer

200μm 200μm 1μm

Proton Exchange Membrane (PEM) Porous Transport Layer (PTL) (Gas Diffusion Layer) Catalyst Coated Membrane (CCM)

slide-4
SLIDE 4

Effect of MPL on PEMFC performance

3 i / A/cm2 0.0 0.2 0.4 0.6 0.8 Ecell / V 0.2 0.4 0.6 0.8 1.0 1.2

PEMFC with MPL PEMFC without MPL

with MPL

Polarization curves for PEMFCs without MPL and with MPL on anode and cathode sides. Error bars represent standard deviation within batch of identically built cells.

without MPL

Positive effects of MPL:

reduces cathode flooding

  • U. Pasaogullari, C.-Y. Wang,
  • Electrochim. Acta 4 9 (2004) 4359
  • L. R. Jordan, A. K. Shukla, T. Behrsing,
  • N. R. Avery, B. C. Muddle, M.Forsyth,
  • J. Power Sources 8 6 (2000) 250

im proves catalyst utilization

  • Z. Qi, A. Kaufman, J. Power Sources,

1 0 9 (2002) 38

Reduces variability in cell perform ance

  • Z. Qi, A. Kaufman, J. Power Sources,

1 0 9 (2002) 38

  • D. Malevich, E. Halliop, B. Peppley, J. Pharoah, K. Karan,
  • J. Electrochem. Soc., 156, B216 (2009)
slide-5
SLIDE 5

Theories explaining MPL effect

Water

4

+ + Oxygen Oxygen Water membrane + + MPL cathode catalyst layer

Hydrophobic characteristic of the MPL forces w ater from cathode tow ards FFP reducing flooding

Porous transport layer (aka GDL)

  • A. Z. Weber and J. Newman, J. Electrochem. Soc.,

152, A677 (2005) Proposed in:

slide-6
SLIDE 6

Theories explaining MPL effect

Water

5

Hydrogen Hydrogen + + + + + + Oxygen Oxygen Water membrane

water drag with proton water back diffusion

MPL

  • G. Lin and T. V. Nguyen, J. Electrochem. Soc., 152, A1942 (2005).

Proposed in:

MPL facilitates w ater back diffusion providing better hum idification of m em brane and catalyst layers

anode catalyst layer cathode catalyst layer

slide-7
SLIDE 7

Theories explaining MPL effect

Water

6

+ + Oxygen Oxygen Water membrane + + MPL cathode catalyst layer

MPL m akes open pathw ays for gaseous

  • xygen to be transported

to catalyst layer

Porous transport layer (aka GDL)

Proposed in: water water water

  • J. T. Gostick, M. A. Ioannidis, M. W. Fowler, M. D.

Pritzker, Electrochem. Comm. 11, 576 (2009)

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SLIDE 8

Approaches to examine proposed mechanisms Flow visualization

7

Neutron radiographs of water distribution in flow field channels – effect of PTL (J.P. Owejan, T.A. Trabold, D.L. Jacobson, M. Arif, S.G. Kandlikar, Int. J. Hydrogen Energy, 32, 4489 (2007)

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SLIDE 9

Approaches to examine proposed mechanisms

8

Electrochemical Impedance Spectroscopy (EIS)

Setup 1

  • r

Setup 2

resistance Rs I=V*Rs

  • 1

EIS enabled potentiostat or potentistat+ impedance analyser impedance analyser V electronic load PEM fuel cell

High-current impedance Low-current impedance

slide-10
SLIDE 10

EIS response of PEM fuel cell

9

Z' / Ω cm2 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Z'' / Ω cm2

  • 0.2
  • 0.1

0.0

1 2 3 0.1 Hz 1 Hz 3 Hz 12 Hz 600 Hz 60000 Hz

High- frequency arc Low- frequency arc Mid-frequency arc High- frequency intercept

slide-11
SLIDE 11

Z' / Ω cm

2

0.0 0.1 0.2 0.3 0.4 0.5

  • Z'' / Ω cm

2

0.2 0.1 0.0

210 mA cm-2 300 mA cm-2 400 mA cm-2 500 mA cm-2

Mid-frequency arc: charge transfer resistance

10

R(i=500) R(i=210)

effect of current density on EIS response

  • D. Malevich, E. Halliop, B. Peppley, J. Pharoah, K. Karan,
  • J. Electrochem. Soc., 156, B216 (2009)
slide-12
SLIDE 12

Low-frequency arc: mass-transport resistance

11

Z' / Ω cm2 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Z'' / Ω cm2

  • 0.2
  • 0.1

0.0

0.1 Hz 1 Hz 3 Hz 12 Hz 600 Hz 60000 Hz H2/Air cell H2/(20%O2+He) cell

effect of cathode gas on EIS response

  • D. Malevich, E. Halliop, B. Peppley, J. Pharoah, K. Karan,
  • J. Electrochem. Soc., 156, B216 (2009)
slide-13
SLIDE 13
  • 30
  • 25
  • 20
  • 15
  • 10
  • 5

50 100 150 200 250 300 350

  • 300
  • 250
  • 200
  • 150
  • 100
  • 50

H2 / H2 H2 / Air

Z' / Ω cm2 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Z'' / Ω cm2

  • 0.3
  • 0.2
  • 0.1

0.0

1.5 kHz 24 Hz 12 Hz 2 Hz 60 kHz 0.1Hz

H2/O2 cell H2/Air cell H2/H2 cell

High-frequency arc: membrane resistance

Ecell-Ecell(j=0) / mV Ecell-Ecell(j=0) / mV i / mA cm-2

R=0.1 Ω cm2 12 Diameter of high-frequency arc found to be consistent with the resistance calculated from the known geometry and conductivity

  • f the Nafion membrane
  • J. M. Le Canut, R. Latham, W. Mérida, D. A.

Harrington, J. Power Sources, 192, 457 (2009)

  • D. Malevich, E. Halliop, B. Peppley, J. Pharoah, K. Karan,

ECS Transactions 156, 1763 (2008)

slide-14
SLIDE 14

Z' / Ω cm2 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Z'' / Ω cm2

  • 0.2
  • 0.1

0.0

1 2 3 0.1 Hz 3 Hz 12 Hz 600 Hz 60000 Hz

13

In-series resistance (FFP, endplates, cables etc.) Membrane resistance Cathode charge- transfer resistance Cathode mass- transport resistance

EIS response of PEM fuel cell: arc assignment

total cell resistance (Rcell)

polarization curve

Rcell

E / V

i = 0.21 A cm-2

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SLIDE 15

Effect of MPL on PEMFC EIS response

14

Z' (Ω cm2) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Z'' (Ω cm2)

  • 0.2
  • 0.1

0.0

0.1 Hz 1 Hz 3 Hz 12 Hz 600 Hz 60000 Hz

Impedance diagrams for PEMFC with (2,3) and without (1) MPL fed with H2/ Air. Current density – 0.21 A cm -2.

without MPL with MPL

slide-16
SLIDE 16

Effect of MPL: influence of current density

15

without MPL with MPL

0.3 A cm-2 0.7 A cm-2

slide-17
SLIDE 17

Z' / Ω cm

2

0.0 0.1 0.2 0.3 0.4 0.5

  • Z'' / Ω cm

2

0.2 0.1 0.0

Equivalent circuit fitting

16

W

Ro CPEm Rct CPEdl Zw Rm Randles circuit:

slide-18
SLIDE 18

i / mA cm

  • 2

300 400 500 600 700 800 900

R / Ω cm

2

0.0 0.1 0.2 0.3 0.4 0.5

6 5 i / mA cm

  • 2

300 400 500 600 700 800 900

R / Ω cm

2

0.2 0.3 0.4 0.5 0.6

Effect of current density on cathode charge-transfer and Warburg resistances

Rw Rct Rw Rct Rct+Rw Rct+Rw

17

with MPL without MPL

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SLIDE 19

Time constants for oxygen transport process

18

Experimentally determined: Theoretically predicted:

slide-20
SLIDE 20

MPL effect models

19

Model A: MPL promotes water back diffusion Model B: MPL forces water to FFP Expected effects:

  • Increased amount of water in cathode

catalyst layer

  • Reduced membrane resistance
  • Reduced water content in cathode PTL

Expected effects:

  • Reduced amount of water in cathode

catalyst layer

  • Increased water content in cathode PTL
  • bserved

not observed