© Fraunhofer ISE

Dr. A. Georg, U. Groos, Dr. M. Klingele, Dr. S. Metz, Dr. S. Ouardi, Dr. A. Schaadt, Dr. T. Smolinka, M. Zedda

Fraunhofer Institute for Solar Energy Systems ISE

www.h2-ise.com

www.ise.fraunhofer.com

FRAUNHOFER INSTITUTE FOR SOLAR ENERGY SYSTEMS ISE DIVISION »HYDROGEN TECHNOLOGIES«

Ex-situ characterisation tools for materials and components in PEM water electrolysis and fuel cells

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Ex situ analysis of materials and componentsOverview

Inductively coupled plasma mass spectroscopy (ICP –MS) for element analysis of liquids

Capillary flow porometry (CFP) for through-plane gas permeability of porous media

Porosimetry for absolute and relative in-plane gas and liquid permeability

Environmental Scanning Electron Microscopy (ESEM) and Energy Dispersive X-ray Spectroscopy (EDS)

X-ray computed tomography(Micro CT)

Electrical conductivity and interfacial contact resistance (ICR) and force-displacement measurements

High temperature and Near ambient pressure X-ray photoelectron spectroscopy (HT NAP-XPS)

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Capillary flow porometry for porous media

Gas-liquid displacement porometrywith pressure step/stability method:

Determination of pore diameter:

Largest / mean / smallest

Through-plane gas permeability

Relationship capillary pressure vssaturation

Inner (mean) contact angle

Important parameters for PTL design

0.00 0.01 0.02 0.03 0.040.0

0.3

0.6

0.9

1.2

1.5

1.8

Volu

me

flow

Q /

l·min

Pressure p / bar

Wet curve Interpolated dry curve Half interpolated dry curve

0.0 0.2 0.4 0.6 0.8 1.00.00

0.01

0.02

0.03

0.04

0.05

0.06

Capi

llary

pre

ssur

e p c /

bar

Saturation s

1. Measurement 2. Measurement Van Genuchten

Smallestpore

Largestpore

Meanpore

Porolux 1000 from Porometer

Sample holder Contact angle measurement set up

Bromberger, K., Ghinaiya, J., Lickert, T., Fallisch, A., Smolinka, T.: Hydraulic ex situ through-plane characterization of porous transport layers in PEM water electrolysis cells, Int. J. Hydrogen Energy, Vol. 43, Issue 5, 2018, 2556-2569, https://doi.org/10.1016/j.ijhydene.2017.12.042.

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0 100 200 300 400 5000

200

400

600

800

1000

Pres

sure

dro

p ∆ p

/ m

bar

Volume flow Q / l·min

PTL 1 PTL 2 ∆p ∆p κin-plane κin-plane

2x10-12

4x10-12

6x10-12

8x10-12

10-11

Perm

eabi

lity κ

/ m2

In plane permeability of porous media

Absolute and relative in-plane gas and liquid permeability

Test set up with a cell area of 25 cm²

Method established for GDL / PTL etc. using Darcy or Darcy-Forchheimer law

Test set up for in-plane permeability measurements and detailedview on test cell

In-plane pressure difference and gas permeability for different gas flow rates of sintered titanium based PTLs

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Measurement of in-plane and through-plane resistance/conductivity as function of compression

Interfacial Contact Resistance (ICR) of passivation layers

Thickness measurement by eddy current sensors (resolution 3 µm)

Combination of clamping pressure and thickness measurement allows a force/displacement analysis

Electric conductivity and interfacial contact resistanceUnderstanding of internal cell resistance and individual contributions is crucial for stack design

ICR1

Rbulk

ICR24w

Electricalinsulation

Stainlesssteel plate

PTL sample

Pressure

Voltage probe

I2w

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Measurement of through-plane resistance of different materials

Interfacial contact resistance (ICR) between bipolar plate and GDL

Bulk resistance of GDL

Thickness measurement

Through-plane resistance and interfacial contact resistance

Au

Au

coatedBPP

GDL sense (-)

source (-)

source (+) sense (+)

Homogeneouspressure distribution

ICR of uncoated and coated SS 316 L before & afeter electrochemical testing

Measurement principleMeasurement setup

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Inplane & through-plane resistance

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Electrochemical characterization of bipolar plate materials

Cyclic voltammogramm of stainless steel at different temperatures, electrolyte: 0.001 M H2SO4+0.1 mg HF

Electrochemical measurements is combined with elemental analysis of the electrolyte with ICP-MS (here during potentiostatic test at 0.8 V for 4 days), SEM/EDX analysis, and contact resistance measurement.

Test cell made of PTFE, integrated heating, gas (Ar or O2), working electrode (WE) (sample), reference electrode (RHE), counter electrode (CE).

Gaskatel FlexCell®

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Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS)

Element analysis of liquids with ICP-MS. In Ar-plasma the molecules are destroyed and ionised. In the mass spectrometer the ions of every mass are counted.

ICP-MS product water analysis of a fuel cell stackwith metallic bipolar plates (extreme example)

ICP-MS analysis of electrolyte after ex-situ corrosion test (24 h at 0.8 V) of metallic bipolar plates. (ISE-coating comparedwith Au plated and uncoated stainlesssteel substrate)

Agilent MS 7500 ce

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Scanning Electron Microscopy and Computed X-ray Tomography

Environmental Scanning Electron Microscopy (ESEM) and Energy Dispersive X-ray Spectroscopy (EDS) for element analysis

Platinum

Ruthenium

ESEM

Computed X-ray tomography with a nominal resolution of 600 nm

non-destructive scanning and 3D reconstruction of internal micro-structures incl. compression stage

Skyscan 2211 from BrukerFEI Quanta 400 MK II

3D r

eco

nst

ruct

ion

of

a PT

L fo

r PE

M w

ater

el

ectr

oly

sis

Zielke, L., Fallisch, A., Paust, N., Zengerle, R., Thiele S.: Tomography based screening of flow field/currentcollector combinations for PEM water electrolysis. RSC Adv (2014), 10.1039/c4ra12402b

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Fenton testing

Investigating the chemical stability of fuel cell or electrolysis membranes regarding radical attacs

Membrane degradation: cations catalyze radical formation from H2O2 and radicals attac the membrane polymer

Fenton test: Insertion of membrane in 30% H2O2 with metal salts (typically Fe2+) and heat at 80°C

Measurement of Fluoride-release over time as measure for membrane decomposition

F- measurement with ion sensitive electrode

Use of chemical inert polymer bottles (safer and less contamination than glass)

Testing with different temperatures, cations and/or membranes; variation of cation concentration membranes after Fenton-

Test with: I: Al, III: Fe,

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Near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS)

X-ray source: AlKα (1.4 keV)

Spot size 300 µm Ø

Pressure:10-8 mbar up to 20 mbar

Sample temperature:5 - 800 °C

Sample size up to 120 mm ∅

Plasma cleaning of the surface

Fully automated vacuum and gas dosing system(N2, Ar, H2, O2)

EnviroESCA(SPECS GmbH)

EnvironESCA: Electron spectroscopy for chemical analysis under environmental conditions at near ambient pressure of catalysts, liquids and liquid-solid interfaces.

Surface characterisation of an IrO2 based anode for PEM water electrolysis as received, after short-term and long-term operation

320 300 2800.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Nor

m. I

nten

sity

Binding energy [eV]

IrO2 Electrode short time long time New Ir 4f7/2Ir 4f5/2

C 1s

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Thanks a lot for your kind attention!

Fraunhofer Institute for Solar Energy Systems ISE

Electrolysis Fuel Cell Systems Thermochemical Systems

Dr. Tom Smolinka Ulf Groos Dr. Achim Schaadttom.smolinka@ise.fraunhofer.de ulf.groos@ise.fraunhofer.de achim.schaadt@ise.fraunhofer.de

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