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  • JACQUES Pierre-André, PAUCHET Joel, NAYOZE Christine, GUETAZ Laure

    MEA; MANUFACTURING PROCESSES & QUALITY TECHNIQUES

    pierre-andré.jacques@cea.fr

  • | 2

    MEA: THE DIFFERENT STEPS OF MANUFACTURING

    7 layers assembly

    CCM + rim + GDL GDE + membrane +rim

    AL printing

    Ink formulation

    Catalyst ionomer+ Material technology choice

    Process

    Technology

    choice

    ProcessImpact on: - performance

    - durability

    - cost stack

    design

  • | 3

    FIRST: 7 LAYERS ASSEMBLY

    misaligned GDL

    Air pocket under subgasket Dust on the subgasket

    Alignement of the MEA (GDL + CCM + rim) is a requirement.

    1 defected MEA (misaligned, issue on the rim) causes failure on the whole stack:

    - Leakage, gas by pass, not homogenous compression

    Check tolerance of MEA alignment Vs Stack tolerance chain.

    At lab scale : not an issue, what about high speed manufacturing ?

    wrinkle

    2D control

    on 50 points

  • | 4

    GDL: A KEY ELEMENT

    Understanding the impact of GDL properties on stack performance

    is still to be improved : Defect definition

    43%

    18%

    21%

    2% 16%

    47%

    20%

    23%

    1% 9%

    50%HR

    100%HR

    Channels DM MPL AL

    Ionomere

    Influence on

    performance

    Thermal property of different GDL

    with defects and without defects

    Manufacturing

    • Process/parameters

    • Requirements

    • Selection (criteria)

    Assembling

    • Process/parameters

    • Requirements

    Testing

    • Performance

    • Durability

    • Requirements

    • Acceptance (criteria)

    1. Better understand the link between (local) properties of GDL to their performance/durability

    2. Propose improvements

    1. What is a defect?

    2. Define selection/acceptance criteria as a trade-off

    quality/price:

    • General ones?

    • Specific ones depending on the MEA, BPP, OC…

    3. On-going DIGIMAN project as an example

    Off-line characterization

    On-line characterization

    3D image of a commercial GDL

    Performance w/wo defects

    Samples batch 1

    Samples batch 2

  • | 5CEA LITEN DEHT | June 2014

    ACTIVE LAYER: IN PLANE

    Electrode characterization

    Pilot line of electrode manufacturing in line detection

    CCM

    Macro defect:

    optical check thanks to contrast AL Vs support

    Hot spot  thicker smudge

    Cool spot  thinner coating

    Defects detection on GDE with

    Reactive Impinging Flow Excitation (RIF)

    Link between defects detection and

    catalyst loading on GDE : On line

    adaptation of the ink for each :

    - Process

    - Material technology (ionomer, catalyst)

    - Electrode design

    numbering

  • | 6

    Active Layer inhomogeneity

    - no AL  membrane penetration

    No Pt band in the membrane:

     validates the sample preparation

    Pt band Might cause issue on durability

     Impact on BoL performance ?

    Not or only few (reinforced membrane)

    SEM observation after : 150 hrs – 10,000 km in HyKangoo

    Pt band

    CCB Membrane stress

    ACTIVE LAYER:

    IMPACT OF THE PROCESS

    Holes and cracks in the AL impact

    the membrane integrity;

    Cracks from : MPL and/or process

    20 µm

    Inactive Pt

    MEA cross section

    AL front view

  • | 7

    ACTIVE LAYER: THROUGH PLANE

    CCM cross section : SEM characterization

    Aggregates without polymer  inactive Pt, loss of ECSA

    Membrane penetration in AL crack  membrane weak point ?

    AL aggregates penetration in AL  thinner membrane, weak point ?

    10 µm 10 µm

    Catalyst aggregates :

    - no ionomer,

    - no catalyst ripening

    - Inactive Pt

     impact on Pt loading

     Impact on ageing

    - Deformation

    of the membrane

    - Short circuit / hole

     Impact on ageing

     failure

    CCM

    Membrane stress

    F in green

    Pt in red

  • | 8

    INK FORMULATION

    The ink preparation process affecting:

    - the numbers of aggregates and the viscosity To be tuned for each material technology (ionomer, catalyst) and process

    Impact of dispersion process parameter

    0

    0,5

    1

    1,5

    2

    0,01 0,1 1

    P o

    p u

    la ti

    o n

    w t%

    Size (µm)

    Avant dispermat

    5 min dispermat

    15 min dispermat

    80 nm -> 120 nm 520 nm -> 1050 nm

    0

    10

    20

    30

    40

    0,1 1

    p o

    p u

    la ti

    o n

    w t%

    Size (µm)

    Après dispermat

    Après aquivion

    780 nm

    In it

    ia l

    in k

    Modification of solvent ratio and

    components introduction

    + Modification of ratio components

    O p

    ti m

    iz e

    d i

    n k

    After dispersion

    After complete

    formulation

    CATALYST AND INK PREPARATION

    Electroacoustic + zeta probe :

     chasing the granulometry of the ink

     Ink validation before AL printing

    0

    0,2

    0,4

    0,6

    0,8

    1

    1,2

    1 10 100 1000

    P o

    p u

    la ti

    o n

    w t%

    Size (µm)

    Essai 1

    Essai 2 Essai 3

    39 µm

    Trial 1

    Trial 2

    Impact of solvent and ratio components

  • | 9

    OPERANDO CHARACTERIZATION OF MEA :

    SEGMENTED BOARD

    Textured electrode

    Current density distribution mapping CDDM

     MEA homogeneity

     impact of RH, stoichio, fuel composition

    Uniformed electrode

    2

    1

    A tool to study the impact of one

    « defected » MEA on the stack

    and « defect » propagation

    Different AL designs give different CDDM

  • | 10

    OPERANDO CHARACTERIZATION OF MEA :

    MAGNETIC FIELD AND ELECTROCHEMICAL IMPEDANCE

    Instrumented stack integrating a « defected MEA »

    0 0.2 0.4 0.6 0.8 0

    0.2

    0.4

    0.6

    0.8

    1

    1.2

    Re(Z) (.cm²)

    -I m

    (Z )

    (  .c

    m ²)

    segment n°10

    data

    fit

    0 0.2 0.4 0.6 0

    0.2

    0.4

    0.6

    0.8

    1

    1.2

    Re(Z) (.cm²)

    -I m

    (Z )

    (  .c

    m ²)

    segment n°10

    data

    fit

    Evolution of EIS between :

    homogeneous AL and voluntary defected AL

    Lyes IFREK, Thesis, 2017

    Thomas Gaumont, Thesis, 2017

  • | 11

    SEM on MEA cross section

    after 900 hrs (stationary + Fc-DLC) CEA CCM:

    - cathode loading 0,35 mgPt/cm2

    - Anode loading 0,1 mgPt/cm2

    DURABILITY TEST WITH HIGH QUALITY ACTIVE LAYER

    @ 0,6 A/cm2

    @ 0,4A/cm2

  • | 12

    • What is a defect ?

    Need to establish defect specification and ranking

    - Failure of the stack - Decrease of BoL performance - Decrease of durability  decrease of EoL performance Vs failure - Next generation material

    Understanding the link :

    1\ material and component specification  stack performance

    2\ material and component specification  stack durability

     Material and component validation :

    - Definition of the main parameters to be tracked - Definition of the quality assurance (on line Vs off line) - 100 % areal checking Vs selected validation points

    - Available tools for defect detection ?

    CONCLUSION

  • Defect < Component specification < over quality

    MEA Integration

    Full stack characterisation

    In situ and integrated component characterisation

    Ex situ and single component characterisation

    Modelling as a tool

    Ink processing & manufacturing

    Cell performance

    Component structure

    Inferface optimisation

    Impact on each physical parameter

    Inspection of the main parameter quality management policy

  • | 14

    • Irina Profatilova • Frédéric Fouda-Onana • Marie Heitzmann • Sebastien Rosini • Fabrice Micoud • Sylvie Escribano • Dominique Thoby • Arnaud Morin • Claude Bonin • Pierrick Buvat • PEMFC team @ CEA-Liten

    • Michael Ulsh • Guido Bender

    THANKS TO :

    • Yann Bultel

    • Lyes Ifrek

    • Thomas Gaumont • Olivier Lottin

    • Steffen Theuring

    • Coen Van Aken

  • Commissariat à l’énergie atomique et aux énergies alternatives

    17 rue des Martyrs | 38054 Grenoble Cedex

    www-liten.cea.fr

    Établissement public à caractère industriel et commercial | RCS Paris B 775 685 019

    MERCI POUR VOTRE ATTENTION

    THANKS FOR YOUR ATTENTION