Res. Chem. Intermed.
, Vol. 32, No. 5–6, pp. 533–542 (2006)
Also available online - www.vsppub.com
Gas diffusion electrodes for polymer electrolyte fuel cell
using sulfonated polyimide
, KENICHI OKAMOTO
, KENJI MIYATAKE
and MASAHIRO WATANABE
Clean Energy Research Center, University of Yamanashi, 4 Takeda, Kofu 400-8510, Japan
Faculty of Engineering, Yamaguchi University, 2-16-1, Tokiwadai, Ube, 755-8611, Japan
Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi,
4 Takeda, Kofu 400-8511, Japan
Received 7 December 2004; accepted 29 December 2004
Abstract—Gas diffusion electrodes for high temperature polymer electrolyte fuel cells (PEFCs) have
been prepared by using a novel proton conductive sulfonated polyimide (SPI) electrolyte. The catalyst
layer was composed of Pt-loaded carbon black (Pt-CB) and SPI ionomer. The polarization properties
and the microstructure of the catalyst layer were investigated as a function of the SPI/CB weight ratio.
The anodic polarization was found to be negligibly small for all the compositions examined. The
highest cathode performance was obtained at SPI/CB = 0.5 (by weight), where the best balance of
high catalyst utilization and oxygen gas diffusion rate through the ionomer was obtained.
Keywords: Polymer electrolyte fuel cell; gas diffusion electrode; sulfonated polyimide electrolyte.
Polymer electrolyte fuel cells (PEFCs) have been attracting much attention as a
clean power source for electric vehicles (EVs) or residences due to their high-
energy conversion efﬁciency and low emission of pollutants . One of the
challenges for PEFCs is to elevate the operating temperature to values above 100
because of improvements in CO tolerance of the anode and oxygen reduction
kinetics at the cathode. The latter could decrease Pt catalyst loading and also
the over-potential, resulting in the higher energy efﬁciency of the cell besides
an efﬁcient heat exchange. The electrolyte membrane commonly used for PEFCs
consists of perﬂuorosulfonic ionomers (PFSIs), such as Naﬁon, because of its
high proton conductivity and high chemical and mechanical stability. However,
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