Short communicationStainless steel bipolar plate coated with carbon nanotube (CNT)/polytetrafluoroethylene (PTFE) composite film for proton exchange membrane fuel cell (PEMFC)
Introduction
The proton exchange membrane fuel cell (PEMFC) is an ideal candidate for automotive propulsion application, because it has high efficiency and cleanliness as a power source. Graphite bipolar plate has excellent natures in terms of chemical stability and electrical conductivity. However, it contributes significantly to the weight and cost of PEMFC although automotive application requires miniaturization and low cost. Metals such as stainless steel have been considered as alternative materials to graphite bipolar plate, because they are produced using chemical etching or press processes. Moreover, they are generally thinner than graphite bipolar plates thus resulting in a fuel cell stack that is both light in weight and small in volume.
An ideal bipolar plate material should be corrosion-resistant, because pH in fuel cell has a low value of 3.7–4.1 [1]. However, metal bipolar plates were corroded in the strong acidic environment in PEMFC. Therefore, carbon-based [2], [3], [4], [5] and metal-based [6] coating on metal bipolar plates has been studied to improve corrosion resistance and conductivity. Although amorphous carbon film coating on the metal bipolar plates increases the output power of fuel cell [2], [3], this technique is far from the practical application, because its coating cost using the chemical vapor deposition (CVD) method is of high value.
In this study, electrically conductive composite film consisting of carbon nanotube (CNT) and polytetrafluoroethylene (PTFE) was coated on stainless steel bipolar plates. Moreover, the contact resistance between the surface of the bipolar plate and the membrane electrode assembly (MEA), and the output power of the fuel cell were investigated.
Section snippets
Formation of CNT/PTFE composite film
CNT/PTFE composite film was formed from CNT and PTFE dispersion fluids. The CNT dispersion fluid was made from multi-walled type CNTs. Cellulose derivatives were added to the water to disperse the CNT. This CNT dispersion was made by means of the technique reported in Ref. [7]. The CNT concentration in the dispersion fluids was 3%. The CNTs were well-dispersed in the water even when the CNT concentration was of a high value. Water-based commercial PTFE dispersion was used in this study. The
Result and discussion
Fig. 1 shows the mixed dispersion fluids of CNT and PTFE made by two kinds of the methods. Fig. 1(a) shows the fluid which made by mixing the powdered CNT and the PTFE dispersion as a reference. When the powdered CNT was used, both the CNT and the PTFE were settled to the bottom of the bottle. Clear supernatant fluid was appeared at the top. Fig. 1(b) shows the dispersion fluid made by mixing dispersion fluids of the CNT and the PTFE. The CNT was well-dispersed in the PTFE dispersion. The CNT
Summary
The CNT/PTFE composite film was formed by using the dispersion fluids of the CNT and the PTFE. This film showed properties of electrical conduction facilitated by the CNTs within the film. The conductivity of the composite film increased with an increase in the CNT concentration. The film having the conductivity of 12 S cm−1 was observed at the CNT concentration of 75%. The fuel cell assembled with the stainless steel bipolar plates, which was coated with this composite film, showed higher output
Acknowledgements
This work is supported by the research and study promotion program in Tokai University and the coordinate project for application and promotion of intellectual property by Foundation of Kanagawa Academy of Science and Technology. The authors would like to thank Mr. Y. Miyamoto of the Technical Service Coordination Office, Tokai University for the TEM investigations.
References (8)
- et al.
Electrochim. Acta
(2003) Surf. Coat. Technol.
(2007)- et al.
Diamond Relat. Mater.
(2007) - et al.
J. Power Sources
(2007)
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