DEVELOPMENT OF HIGH OXYGEN BARRIER PEM FOR DURABLE PEFC SYSTEMS
Yasir Arafat HUTAPEA
Department of Hydrogen Energy Systems, Kyushu University【Scientific Background of Research Proposal】
Polymer Electrolyte Membrane (PEM) Material Used for Fuel Cells
Nafion（Fluorine-based）
Alternative PEM（Hydrocarbon）☺ Simple structure and easy to modify☺ High proton conductivity and heat stability☺ High proton conductivity☺ High chemical durability
Standard PEM for fuel cells【Current problem for PEM】
Chemical decomposition of PEM due to theattack from radicals generated duringoperation【Current Research Results】
SampleNamePVA(meq.)

1,3-propane
sultone (meq.)

Sulfonation
Degree (%)

IEC(mmol/g)

Sultone 21253

1.80

Sultone 1

1159

2.41

Sultone 0.5

10.5

51

1.09

Gas Barrier Properties
Oxygen Barrier

Hydrogen Barrier
80˚C80˚C

O2 barrier is 600
times than Nafion

H2 barrier is 27
times than Nafion

Traditional research approach➢ Introduction of molecular structure (polyphenylene, fluorine-based) with highchemical durability➢ Blending with radical scavengers (CeO2 ,etc.）

Problems such as limited structure and uneven distribution of radicalscavengers inhibit these approaches to be a fundamental solution

Decomposition of PEM
Attack from radical species (•OH, •OOH ) on PEM leads to PEM decomposition

Radical formation on PEM

O2: Radicals（∙OH, ∙OOH）
Anode

1. Penetrated oxygen gas to theanode side
2. Penetrated oxygen gas to theeluted Pt
3. Radical formation by twoelectron reaction at the cathode

Cathode
①

H2

O2

O2

②
Pt
H+O2

③

OHOHOHOHOH OHOHOHOHd• High oxygen barrier property of PVA is obtainedfrom strong intermolecular force between OHgroups. → small main chain distance• After sulfonation, strong intermolecular force
remains existed between sulfonic acid groups.

Structure vs Oxygen Permeability

X-ray Diffraction

Crystallinity
Larger Main ChainDistance

O2

O2

Smaller Main
Chain Distance

H2O “Oxygen penetration through PEM

Crystalline

is the main cause of radicalformation”

Polymer Electrolyte Membrane（PEM）

Amorphous

Polymer Main Chain Distance[Question]
Can we suppress PEM decomposition by less radical formation if oxygen gas
never penetrate PEM ?

O2
SmallerLarger【Research Objective】• Nafion 212 is slightly more crystalline thanSultones.
• However, Sultones show smaller distance
between its polymer main chain.

By developing high oxygen gas barrier Polymer Electrolyte Membrane (PEM) tosuppress the radical's generation due to oxygen permeation through PEM, thedecomposition of PEM is fundamentally solved.
CathodeH2

①

O2

O2

②O2

Ptpermeation and suppress PEM
decomposition
・Higher performance by thinner PEM

PEM redesign
・PEM redesign based on durability analysis③resultH 2O【Research Impact】
Possibility of using various materials→ Material Chemistry
Application to water electrolysis→ Hydrogen energy field➢ PEM with 100 times more O2 barrier than Nafion➢ Thinner PEM can be applied【Research Plan】
Full Ph.D. Project Time Schedule2020 - 2021
➢ Development of High
Oxygen Barrier PEM

2021 - 2022

2022 - 2023

➢ Optimized High Oxygen Barrier PEM* Improved durability* Article publication➢ Combination of High Oxygen
Barrier PEM and High Oxygen
Permeable Ionomer for PEFCs
Application* Improved performance anddurability* Article publication* Ph.D. thesis writing* Preparation* Characterization➢ Development of High Oxygen* PEM durability evaluation
Permeable Ionomer* Improved catalytic performance* Article publication* Article publication

Proton Conductivity
100

Proton Conductivity (mS/cm)

Anode【Research Direction】
Develop high oxygen gas barrier PEM
・To reduce radicals derived from oxygen

Sultone 1Sultone 0.5
Nafion 212

80

Although crystallinity relates to gas barrier
property, the dominant factor for Sultones wasgiven by “polymer main chain distance”.

Thermogravimetric Analysis
60˚C60Absorbed water40
20Side-chain

020406080
Relative Humidity (%)• The
optimumproton
conductivity is achieved bySultone 1 (70 mS/cm),
higher than Nafion 212 at
the same condition.
• Proton conductivity in higher
temperature and humidity is
not available yet due tothermal stability issue andswelling, respectively.

Main chain100• Evaporated
andboundwatermolecule
weredecomposed at thefirst step.
• Second
step
relates
todesulfonation.
• Mainchain
degradation
wasrecorded at thethird step.

Differential Scanning Calorimetry
Glass transition temperature

103oC

93oC
95oC

• Glasstransition
temperatureofSultones are lower
thanNafion(130°C)→
optimizing
testcondition• Sultones
withlower sulfonation
degree need to bemeasuredfornegative control【Summary and Future Plan】

Synthetic Route
1. The developed PEM shows significant high O2 and H2 barrier compared to Nafion 212.
NaH+Poly(vinyl alcohol)
PVAHigh gas barrier polymer

DMSO
rt, N2, 24h

1,3-Propane-sultone

2. The high gas barrier properties of Sultones comes from its small main chain distance.
Watersoluble3. The optimum proton conductivity was shown by Sultone 1 (70 mS/cm) (60oC, 70%RH).
1. Thermal stability improvement by modifying crosslinking method.

PVA-SultoneMembrane
Preparation

Cross-linked PVA-sultone(Sultone x)

CrosslinkglutaraldehydeHigh Oxygen
Barrier PEM

2. SAXS analysis to investigate the distance between sulfonic acid group of PEM.

3. OCV holding test for PEM chemical durability measurement.