(576d) Performance of the Novel Ultra-Thin Proton Exchange Membrane Based on Poly(arylene ether sulfone)s for Pemfcs

Performance
of the Novel Ultra-thin Proton Exchange Membrane Based on Poly(arylene ether
sulfone)s for PEMFCs

Yang
ZHAO, Xue LI, Xiaofeng XIE*

Institute of Nuclear and New Energy Technology,
Tsinghua University, Beijing, 100084, China

xiexf@tsinghua.edu.cn

Several perceived
problems of Nafion membranes including high cost, high fuel permeability and restricted
properties under the more stringent operating conditions (at temperatures above
80ºC and relative humidity (RH) conditions below 50%), have been gradually
emerging in the developing process. In order to solve these problems, the novel
ultra-thin proton exchange membrane based on poly(arylene ether sulfone)s is designed,
prepared, and investigated. We use
the atom transfer radical polymerization (ATRP) to prepare the membrane based
on sulfonated poly(arylene ether sulfone) (SPAES), and the chemical structure
of the membrane is shown in Scheme 1. This graft copolymer, of which
architecture is comprised of a hydrophobic backbone that contain considerable
flexible ionic side chains, has the potential to provide well-interconnected proton
transporting pathways due to enhanced phase-separated morphology. The cells
based on same hydration degree and different membranes were shown in Scheme 2. The
diffusion coefficient of hydronium ions was used to forecast the proton
conductivity of SPAES membranes, while the diffusion coefficient of water
molecules was used to investigate the diffusion of water from cathode to anode.

Scheme 1. The
chemical structure of the membrane.

Scheme 2.
The cells based on same hydration degree and different membranes:

A)
Nafion 211; B) SPAES.

This method could induce
phase-separated morphology between hydrophilic ion-conducting channels and the
hydrophobic matrix into the novel ultra-thin membranes.
The morphology of SPAES
membrane by TEM and SAXS showed that a wormlike and interconnected hydrophilic
network of small ionic clusters were observed, higher than that of Nafion,
which had a cluster-network morphology by narrow ionic nanochannels. Measurement
of physical properties showed that these novel ultra-thin membranes were available
for PEMFCs applications. The water uptake, swelling ratio and fuel permeability
were each improved by lengths of the side chain. Future studies will focus on
improving the oxidative stability of these materials, further enhancing
conductivity by improving IEC, and evaluating PEM performance in a single cell
PEMFC test.

Keywords£ºProton
Exchange Membrane£» Ultra-thin
membrane£» Atom Transfer
Radical Polymerization£» Phase Separated Morphology.

Acknowledgements: This work was supported by the National Natural
Science Foundation of China (51573083) and Intergovernmental International
Scientific and Technological Innovation Cooperation Key Projects
(2016YFE0102700).