che_february-2025 - 33

PEMs typically
expand when hydrated.
In-plane
expansion can
not
only
worsen
the yield of membrane
production
and subsequent
processes, but is
also
believed
to
FIGURE 3. Perfluorinated sulfonic-acid polymers exhibit high proton conductivity,
which is thought to be caused by the formation of ion clusters [7 ], as
shown here
method to improve electrolysis efficiency
is to use a polymer with a high
IEC. Reducing membrane thickness
is also an effective method to reduce
membrane resistance, but because
hydrogen-shielding ability decreases,
there is a trade-off between
improving electrolysis efficiency and
safety. A technique to minimize the
impact of this compromise is the use
of a GRC, which is a catalyst additive
that converts the hydrogen that
has permeated through a PEM into
water via a reaction with oxygen.
This technique allows for a dramatic
reduction in the concentration
of hydrogen in the anode, enabling
differential high-pressure water electrolysis
under safe conditions. Platinum
is known as an effective GRC
[10]. By applying a GRC and membrane
thinning, it is possible to improve
hydrogen shielding ability and
electrolysis efficiency.
There is also a need to enhance the
chemical stability of PEMs to withstand
the presence of hydroxyl radicals
generated during water electrolysis.
A radical scavenger is a chemical
species as an additive to reduce the
amount of hydroxyl radicals by converting
the radical into a chemically
inert compound, which can suppress
the decomposition of polymer. In fuel
cells, inorganic compounds, such
as cerium, manganese, chromium,
cobalt and aluminum have been realized
to act an effective radical scavenger,
although some compounds
have a problem of leaching out during
power generation [11].
impact electrolysis
performance.
Reinforcement
can be applied to
suppress the rate
of dimensional
change in the inplane
direction.
Polytetrafluoroethylene
(PTFE) has been used as
a reinforcement material, enabling
dramatic reductions in the rate of
dimensional change.
As described previously, PEMs
can be improved with a combination
of the proper polymers, additives
and reinforcing materials, along
with meticulous attention to design.
However, trade-offs and safety
should be considered when optimizing
the materials to achieve the
target performance.
Further progress in PEM design
technology is required to balance the
four required characteristics for effective
water electrolysis discussed
previously - efficiency,
durability,
safety and compatibility. Additionally,
the performance of PEMs is greatly
influenced by other factors, such
as the catalyst and catalyst-dispersion
ionomers, GDL, flow field and
heat control.
■
Edited by Mary Page Bailey
Acknowledgement
Images provided by authors
For more information, please contact
Shunsuke Tsukuemoto at shunsuke.
tsukuemoto@agc.com
References
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Bornstein, Annu. Rev. Chem. Biomol. Eng.,10, 219 2019.
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7. T. D. Gierke, G. E. Munn, and F. C. Wilson, J. Polym. Sci.: Polym.
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Technologies by Water Electrolysis - Basics and stateof-the-art
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and trends of global hydrogen policies, Tokyo: CMC Research,
Ltd., 69-74, 2023.
9. A. Kusoglu and A. Z. Weber, Chem. Rev., 117, 987, 2017.
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Authors
Yusuke Chiba is a researcher at
AGC, Inc.'s chemicals company.
Working on the development of
ion-exchange membranes since
2023, his responsibilities include
designing ion-exchange membrane
technologies and evaluating
their electrolysis performance. He
holds a Ph.D. in engineering from
Kyoto University, where he studied
supramolecular chemistry and organic synthesis.
Shintaro Hayabe is a researcher
at AGC, Inc.'s chemicals company,
where he has worked since 2017.
He graduated from Keio University
with a M.S. degree in engineering.
He has been working with materials
related to ion-exchange membranes
for about seven years. His
responsibilities include the development
of new ion-exchange
membrane technologies and the evaluation of their
actual performance.
Toshiaki Sawada is a group
leader in the Research & Development
Division of AGC, Inc.'s chemicals
company,
where he has
worked since 2023.He graduated
from Kyoto University with a M.S.
degree in engineering. He has
been working at AGC since 2007
and has been involved in the development
of fuel cell materials
and the fluoropolymer film products. His responsibilities
include determining the direction of new ion-exchange
membrane development.
Shunsuke Tsukuemoto is a
sales and marketing manager at
AGC Chemicals Americas,
Inc.
(AGCCA) and has worked there
since 2023. In his current role, he
is responsible for sales and marketing
of ion-exchange membranes
and ionomer solutions. He
holds a B.S. degree in economics
from Keio University.
Will Salem is a technical manager
at AGC Chemicals Americas,
Inc. (AGCCA) and has worked
there since 2018. In his current
role, he is responsible for AGCCA's
technical service and product development
of ion-exchange technologies.
He holds a B.S. in materials
science and engineering from
Pennsylvania State University.
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