• Corrosion Science and Technology
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• v.22 no.4
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• pp.242-251
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• 2023

The electrochemical corrosion behaviors of 304 stainless steels (STSs) with various coatings (organic coating and dry coating) were examined, and their applicability as bipolar plates in polymer electrolyte membrane fuel cells (PEMFCs) was validated. The results showed that the organic-coated samples had a significant decrease in anodic and cathodic current density compared to the uncoated sample. However, an increase in carbon black content in the organic coating or additional heat treatment at 700 ℃ resulted in a decrease in corrosion resistance. In addition, improvements in corrosion resistance achieved by adding TiO₂ powder to the organic coating were found to be limited. In contrast, dry coating with TiC and CrC exhibited higher corrosion potential, significantly lower current density, and reduced contact resistance compared to the organic coatings. Notably, the TiC-coated sample showed a comparatively lower current density and more stable behavior than the CrC-coated sample. Based on a series of experimental results, a thin TiC coating without defects is proposed as a promising surface treatment strategy for STS bipolar plates in PEMFC.

• Journal of the Korean Ceramic Society
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• v.45 no.8
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• pp.472-476
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• 2008

The surface region of commercial stainless steel 304 and 316 plates has been modified through deposition of the multi-layered coatings composed of titanium film ($0.1{\mu}m$) and gold film ($1-2{\mu}m$) by an electron beam evaporation method. XRD patterns of the stainless steel plates deposited with conductive metal films showed the peaks of the external gold film and the stainless steel substrate. Surface microstructural morphologies of the stainless steel bipolar plates modified with multi-layered coatings were observed by AFM and FE-SEM images. The stainless steel plates modified with $0.1{\mu}m$ titanium film and $1{\mu}m$ gold film showed microstructure of grains of under 100 nm diameter. The external surface of the stainless steel plates deposited with $0.1{\mu}m$ titanium film and $2{\mu}m$ gold film represented somewhat grain growth of Au grains in FE-SEM image. The electrical resistance and water contact angle of the stainless steel bipolar plates modified with multi-layered coatings were examined with the thickness of the gold film.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.89.2-89.2
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• 2011

Stainless steel bipolar plates have many advantage such as high electrical conductivity and mechanical strength and low fabrication cost. However, they need a passivation layer due to low corrosion resistance under PEM fuel cell operation condition. In this study, polyphenyene sulfide(PPS)/carbon composite coated stainless steel bipolar plates were fabricated by compression molding method after PPS/carbon composite sprayed on the stainless steel plate. PPS and carbon were chosen as the binder and conductive filler of passivation layer, respectively. The interfacial contact resistance and corrosion resistance of PPS/carbon composite coated stainless steel bipolar plates were investigated and compared to the stainless steel. The PPS/carbon composite coated stainless steel compared to stainless steel was improved interfacial contact resistance. The results of the potentiodynamic and potentiostatic measurements also showed that the PPS/carbon composite coated stainless steel did not corroded under PEM fuel cell operating conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.353-358
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• 2013

The current interruption method is considered to be an efficient way of measuring the resistance of a fuel cell. In this study, the ohmic area specific resistances (ASRs) of polymer electrolyte fuel cells with different types of bipolar plates were evaluated using the current interruption method. The ohmic ASRs of both a fuel cell with graphite bipolar plates and a fuel cell with graphite foil-based assembled bipolar plates decreased as the current density increased. On the other hand, with increasing cell temperature, the ohmic ASRs of a fuel cell with graphite bipolar plates were decreased by a reduction in the proton transport resistance through the membrane, and the ohmic ASRs of a fuel cell with graphite foil-based assembled bipolar plates were increased by the differences in thermal expansion between different components of the bipolar plates.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.155-161
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• 2013

In this study, a metal-plated polycarbonate was adopted as a material for bipolar plates in a polymer electrolyte membrane fuel cell (PEMFC). The coated layers included 40-${\mu}m$-thick copper, 10-${\mu}m$-thick nickel, and 0.3-${\mu}m$-thick gold that respectively played the roles of current conduction, adhesion between copper and gold, and minimization of surface corrosion. The maximum power of the air-breathing PEMFC with polycarbonate bipolar plates was $120mW/cm^2$, which was similar to that of graphite bipolar plates. Finally, the maximum power of a 12-cell stack of polycarbonate bipolar plates was $132.7mW/cm^2$, and it had an operating time of 12 h. Therefore, this was considered a suitable material for bipolar plates in PEMFCs.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.671-674
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• 2009

In this work, high-aspect-ratio graphite nanofibers (GNFs) were used to improve the electrical, thermal, and mechanical properties of the poly(methyl methacrylate) (PMMA) polymer, as well as those of PMMA composites suitable for use in bipolar plates. In the result, an electrical percolation threshold for the composites was formed between 1 and 2 wt% GNF content. This threshold was found to be influenced strongly by the three separate stages of the meltblending process. The composites exhibited higher thermal and mechanical properties and lower thermal shrinkage compared with the neat PMMA. Thus, GNFs were demonstrated to have positive impacts on the thermo-mechanical properties of PMMA composites and showed, thereby, reasonable potential for use in composites employed in the fabrication of bipolar plates.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.289-292
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• 2009

The fabrication method of glass bipolar plates for micro PEM fuel cell application has been established and performance evaluation has been carried out. The advantages of glass bipolar plates for micro PEM fuel cells are light weight, high chemical resistivity, and easy manufacture. The MEMS fabrication process of anisotropic wet etching, thermal & UV bonding along with metal layer deposition has been introduced. From performance evaluation, it was shown that the micro fuel cell with a metal layer deposited on the reactive area yielded higher power density than the one without it. But both power densities of the two cases showed out to be adequate with the current status of micro fuel cell technology.

• Transactions of Materials Processing
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• v.21 no.8
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• pp.499-505
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• 2012

The fuel cell is a very promising power generation system combining the benefits of extremely low emissions, high efficiency, ease of maintenance and durability. In order to promote the commercialization of fuel cells, a flexible forming process, in which a hyper-elastic rubber is adopted as a medium to transmit forming pressure, is suggested as an efficient and cost effective manufacturing method for fuel cell bipolar plates. In this study, the ability of this flexible forming process to produce the micro channel arrays on metallic bipolar plates was first demonstrated experimentally. Then, a finite element (FE) model was built and validated through comparisons between simulated and experimental results. The effects of key process parameters on the forming performance such as applied load and punch velocity were investigated. As a result, appropriate process parameter values allowing high dimensional accuracy without failure were suggested.

• New & Renewable Energy
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• v.4 no.1
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• pp.31-36
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• 2008

Stainless steels have been widely considered as metallic bipolar plates, due to their passive surface film, which is good for corrosion resistance. However, the high resistivity of the passive film increases interfacial contact resistance between the bipolar plates and the electrodes. Stainless steels thermal spray coated with a mixture of tungsten carbide and stainless steel powders showed that the coated layer safely combined with the matrix but they suffered many internal defects including voids and cracks. Many cracks were formed in the coated layer and the interface of the matrix and the coated layer during the rolling process. The coated and rolled stainless steels showed lower interfacial contact resistance and corrosion resistance than bare stainless steel because of low resistivity of tungsten carbide and numerous defects, which caused crevice corrosion, in the coated layer.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.6
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• pp.554-559
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• 2015

Single cell of PEMFC (polymer electrolyte membrane fuel cell) is composed of bipolar plates, gasket, GDL and the MEA. Bipolar plate's function is the collecting electricity, helping oxygen/hydrogen gas diffuse evenly and draining the water and heat. In this work, we have conducted experiments to low contact resistance and improve the performance of a $25cm^2$ single cell by using metal forms. We have following experimental cases: 1) Conventional graphite serpentine channel bipolar plate; 2) Channel-less bipolar plate with nickel(Ni) based metal foam which coated by various materials. We focused the difference in contact resistance and performance of the single cell with metal foam depending on various coating materials. The experimental results show the similar performance of single cells between with serpentine channel bipolar plates and with channel-less bipolar plate using metal foams. In addition, single cell with metal foam shows potential to higher performance than conventional channel.