Papers by Keyword: Bipolar Plate

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Authors: Gun Hee Kim, Jeong Won Lee, Young Moo Heo, Myeong Woo Cho
Abstract: Subminiature fuel cell is a representative eco-friendly power source which possesses the merits of having the potential of being implemented in portable electronic devices and other subminiature devices, as well as having high energy density as compared to existing secondary cells. The size of the bipolar plate which is implemented in a subminiature fuel cell should be of a small size according to the size of the fuel cell, and the flow channel inside the bipolar plate also has be reduced to match the overall size of the bipolar plate. Therefore, a higher level of difficulty in the manufacturing process is involved in producing bipolar plate for subminiature fuel cells and mass production is extremely difficult. In this study, powder injection molding was applied to the production of subminiature metal bipolar plate to verify the possibility of mass production. For that, a bipolar plate and mold were designed and then a test injection forming was carried out. This was attempted to validate the feasibility of a subminiature metallic bipolar plate prepared through a debinding and sintering process by evaluating its electric conductivity and density.
Authors: Chang Yong Choi, Dae Geun Nam
Abstract: Bipolar plate of stack in polymer electrolyte membrane fuel cell (PEMFC) has high cost and heavy weight. In this study, low carbon steel was used as a base metal of bipolar plate for the lower cost than stainless steels, which are widely researched as bipolar plate. Low carbon steel has not a good corrosion resistance. In order to improve the corrosion resistance and electrolytic conductivity, low carbon Steel needs to be surface modified. We made chromium electroplated layer of 5㎛ and 10㎛ thickness on the surface of low carbon steel, and it was thermally nitrided for 3hours at 1173K in a furnace with 50torr nitrogen gas pressure. Cross-section and surface microstructures of surface treated low carbon steel were investigated using OM and SEM. Also crystal structures are observed by XRD. Interfacial contact resistance and corrosion test were considered to simulate the internal operating conditions of PEMFC stack. The corrosion test was performed in 0.1N H2SO4 + 2ppm F- solution at 80°C. The results show that the surface modified steel plates have good corrosion resistance and relatively low interfacial contact resistance, and it should be candidate material as a bipolar plate of PEMFC.
Authors: Aleksey V. Nikiforov, Irina M. Petrushina, Jens Oluf Jensen, Niels J. Bjerrum
Abstract: Different corrosion resistant stainless steels, nickel-based alloys, pure nickel, Ta-coated stainless steel (AISI 316L), niobium, platinum and gold rods were evaluated as possible materials for use in the intermediate temperature (200-400 °C) acidic water electrolysers. The corrosion resistance was measured under simulated conditions (molten KH2PO4) corresponding to the proton-conducting solid acids or transition metal phosphates as electrolytes. It was shown that, unlike at temperatures below 200 °C, gold is unstable with respect to corrosion in molten KH2PO4. Platinum demonstrated high corrosion resistance and the anodic and cathodic limits were for the first time found for the electrolyte. Nickel, niobium, Inconel®625, Hastelloy®C-276 and Ta-coated stainless steel (AISI 316L) demonstrated high corrosion stability and can be recommended as construction materials for bipolar plates.
Authors: Xiao Jun Yan, Jian Bo Zhuang, Nai Bao Huang, Cheng Hao Liang, Hong Tao Wang, Li Shuang Xu
Abstract: In order to improve the anti-corrosion characteristic of Ag-coated 316SS bipolar plates in PEMFC environment, self-assembled monolayer (SAM) was prepared on its surface by chemical methods. The electrochemical characteristic of modified bipolar plate was also investigated. The results indicated that the SAM was composed of dodecyl thioalcohol. After forming SAM, the bipolar plate’s contact angle increased from 58° to 102°. In addition, its double layer capacitance (Cd) was decreased and charge transfer resistance was increased. The homogeneous SAM, which acted as a protective barrier, inhibited the corrosive ion from corroding. SAM may provide significant protection against corrosion in PEMFC environment.
Authors: György Thalmaier, Ioan Vida-Simiti, Horatiu Vermesan, Cosmin Codrean, Mihail Chira
Abstract: Metallic bipolar plates have the advantages of better manufacturability, higher strength over graphite bipolar plates. The higher strength and toughness of the metallic materials permits the reduction of the width of the bipolar plate so, the volume and mass of the fuel cell can also be reduced. In this paper we are investigating the use of Ni-based amorphous material as a bipolar plate for polymer electrolyte membrane fuel cell (PEMFC). The major requirements of the metallic bipolar plate material are low weight, high corrosion and low contact resistance. The corrosion property of the present alloy has been investigated under conditions that simulate the fuel cell environment. Hydrogen gas and air were bubbled into a 1 N H2SO4 solution at 70 °C, throughout the experiment to simulate the respective anodic and cathodic PEMFC environment. The Ni-base amorphous alloys displayed higher corrosion resistance than stainless steel.
Authors: Wei Yu Ho, Po Yi Tsou, Yen Shuo Chang, Cheng Liang Lin
Abstract: Bipolar plate with multiple functions is one of the essential components of the PEMFC (Proton Exchange Membrane Fuel Cells) stacks. Recently, metallic bipolar plates, particularly different grades of stainless steels, have been increasingly considered due to relatively low cost, good corrosion resistance, sufficient stiffness and excellent flexibility in thin forms, and easy manufacturability [1-3]. However, the major concerns with the use of stainless steel alloys as bipolar plates are their corrosion resistance and interfacial electrical resistance under long operation conditions. Development of advanced ternary nitride coatings such as chromium silicon nitride (CrSiN) has attracted significant industrial interest in recent years [4-11]. Si addition of CrN to form CrSiN films were prepared by cathode arc ion deposition technique and magnetron sputter technique, in order to improve the characterizations of the coatings from structure to corrosion behaviors. It is reported that with the additional element of Si, the hardness and corrosion resistance of the CrSiN coatings can be greatly improved compared to that of the CrN coating. A direct link between the microstructure and mechanical properties of CrSiN coatings with varying Si contents was established [8]. With increasing Si content, the structure of CrSiN coating exhibited the transformation from a columnar-grained structure to a nanocomposite structure, consisting of CrN nanocrystallites embedded in an amorphous matrix. A maximum hardness of 26.6 GPa was found for CrSiN coating with Si content of about 6.7 at.%, while that of pure CrN was 19.4 GPa [6]. Up to now, the CrSiN is yet thoroughly investigated.
Authors: Hao Gao, Jian Lan, Lin Hua
Abstract: Bipolar plate is the key component of proton exchange membrane (PEM) fuel cell and represents a significant part of the overall cost and the total weight in a fuel cell stack. Many research have been done on the manufacturing methods of bipolar plate, among which stamping is very popular. With the increasing of the channel number and complexity, its dimensional error caused by sprinkback will change a lot, even under the same forming process. And the risk of crack is also different. These all impact the quality of bipolar plate. In order to predict deformation of channels and the plate’s quality, the displacement along X-axis, the strain and stress state, and the displacement along Z-axis are measured. The results show that 1) the risk of crack increases with the increasing of channel number; 2) the springbacks increase with the increasing of channel number; 3) the most dangerous point locates on the right internal fillet of the plate’s last section.
Authors: Mao Liang Wu, Zhu Jun Gu, Shou Feng Cao
Abstract: Polymer Electrolyte Membrane fuel cell converts directly electrochemical energy into electricity. Channels in bipolar Plate, a critical component of fuel cell, is designed with Hilbert pattern, which are obtained through offsetting Hilbert curves to both sides according to working size. Polarization curve expresses the same characteristics between Hilbert channel and traditional serpentine and parallel channel. Output current densities of Hilbert channel are equivalent to that of the serpentine channel but larger than that of parallel channel. Simulation demonstrates that fluid flowing states in Hilbert channel are similar to that in serpentine channel and investigates that pressure drop changes with composite Hilbert channel arrangement. Temperature is an important factor influencing fuel cell performance and optimal temperature is close to 333K in this research.
Authors: Jae Young Lee, Bum Choul Choi, Woo Kum Lee, Il Yub Choi, Joong Pyo Shim, Hong Ki Lee
Abstract: Epoxy/graphite powder (GP)/carbon fiber filament (CFF) composites have been prepared in various weight ratios and electrical and mechanical properties were estimated in order to use for the bipolar plate in PEMFC. As was expected, electrical conductivity increased with increasing total carbon content, and the value increased with increasing CFF content in the same carbon content. Tensile strength and flexural strength linearly decreased with increasing epoxy content, however in the same carbon content, these values increased with increasing CFF content. The good effect of CFF on the electrical and mechanical properties was due to the strong bonding between CFF and epoxy resin, which was confirmed by scanning electron microscopy (SEM).
Authors: Jin Sun Lee, Gye Hyoung Yoo, Nam Hoon Kim, Joong Hee Lee
Abstract: The bipolar plates were fabricated using compression molding of graphite (GR), carbon black (CB), multi-wall carbon nanotubes (MWNTs), carbon fibers (CF) and powder type epoxy resin. The electrical conductivity and flexural properties of the composites was increased with increasing the content of fibrous conducting fillers e.g., MWNTs and CF. However, when particulate fillers such as CB and GR were used, the electrical conductivity was increased, but the flexural properties deteriorated with increasing filler content up to certain content. A comparison was also made between the current-voltage (I-V) performances of fabricated composite bipolar plates and commercial graphite bipolar plate. The I-V characteristic in single cell test exhibited more uniform power density at both higher and lower current density and single cell performance increased with increasing the electrical conductivity.
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