Bipolar plates graphite composite

Bipolar plate material Composite of graphite and phenolic resin, Eisenhuth BBP 4 [21]... 

Nonetheless, it can be seen that a range of fillers and polymeric matrices were studied and different ways were used for the production of composite bipolar plates. Graphite and carbon black as fillers are to be found in nearly every study, and accordingly, some polymers are preferred to be used for composite bipolar plates. The reasons for both the fillers and the matrices are obvious. Graphite and carbon black have outstanding chemical stability against corrosion when compared with metallic fillers they achieve an adequate conductivity and are obtainable at a reasonable price. In case of the matrices the chemical corrosion resistance is also a main criterion, and polyolefin materials, fluoropolymers, polyphenylene sulfide (PPS), and phenolic resins are particularly favored. 

Bipolar plates. Graphite-epoxy composite, PEM fuel... 

Section 5.2.2 include composites and metals. From a cost reduction point of view, it is estimated, according to the cost model, that the cost percentage of the plate in a stack can be reduced from -60 to 15-29% if the graphite plate were replaced by the composite plate or metal plate [15]. However, many uncertain factors are involved in the estimation. The progress and major challenges in development of bipolar plates fabricated by these candidate materials will be introduced in the following parf of this section. 

Thermoset-based graphite composite is one of fhe composite materials often used to fabricate bipolar plates. The major filler or reinforcemenf in fhe composite is graphite in a form of powder, flake, or fiber, with additions of carbon powder/fiber (mainly to reduce the cost). 

FIGURE 12.11 Comparison of liquid water transport for two 50-cm single-cell PEM fuel cells using commercial graphite composite bipolar plates (a) surface modified and (b) as received (0.1 A/cm, 1.5/2.0 Hj-air stoichiometry, 100% RH). 

Graphite-based composites and metal/alloy materials both have their own advantages and drawbacks. Current research interests in bipolar plate materials include both graphite composites and coated metals. No doubt progress on these materials will eventually lead to substantial reduction in the volume and cost of the fuel cell stack. 

Huang, J., Baird, D.G., and McGrath, J.E., Development of fuel cell bipolar plates from graphite filled wet-lay thermoplastic composite materials, J. Power Sources, 150, 110, 2005. 

PVDF/graphite composites can lend themselves as the best materials for both molded and coated plates. A key component of a fuel cell stack is the bipolar plate. Also referred to as a water transport plate or a separator... 

The most suitable materials result to be non-porous graphite, metals (aluminum, stainless steel, titanium, and nickel), and composite sohds. Graphite made nonporous by impregnation with impermeable substance was early used for bipolar plates, but its applicability is limited by difficulties in machining and consequent costs. The metal plates present the obvious advantages of high robustness and low... 

Thermoplastic carbon composite materials are a favonrable material combination for bipolar plates becanse they can be mannfactnred by the mass production process of injection monlding [102]. Electrical condnctivity of a carbon composite requires a high content of carbon, nsnally a mixtnre of graphite and active coal. The percolation limit of the graphite in the polymer binder has to be exceeded, leading to direct contact between graphite particles. Additionally, a basic condnctivity of the polymer matrix by the smaller active carbon particles is achieved. The injection... 

Depending on operation temperature the material chosen for the bipolar plate is graphite (or graphite composites) or iron-based alloys (stainless steel) for low- and medium-temperature fuel cells (PEFC, PAFC, MCFC) and chromium or ceramic-based materials for the high-temperature systems (SOFC). In SOFC, for sealing reasons, tubular concepts have also been developed (see Section 8.1.4.6). 

The performance of metallic and graphite composite bipolar plates has been investigated in the European funded DECODE project [72],... 

Fig. 14.16 Selection of bipolar plates having identical flow fleld design investigated within the DECODE project, (a) Uncoated metallic bipolar plate (0.1 mm SS 316 L), (b) gold coated metallic bipolar plate (200 nm Au on 0.1 mm SS 316 L), (c) milled graphite composite bipolar plate. Pictures courtesy of Reinz Dichtungs GmbH, DANA Corporation...

The most surprising finding in this series of experiments was that similar amounts of cationic contaminants have been found in the electrolyte membrane in stacks using metallic and graphitic bipolar plates. The cations found not only represented the composition of stainless steel (Fe, Ni, Cr) but also typical irais found in the tap water (ca, Mg, Cu, Zn) from which the deminerahzed cooling water... 

Dhakate S, Mathur R, Kakati B, Dhami T (2007) Properties of graphite-composite bipolar plate prepared by compression molding technique for PEM fuel cell, bit J Hydrogen Energy 32 4537 543... 

Lee Y-B, Lee C-H, Kim K-M, Lim D-S (2011) Preparation and properties on the graphite/ polypropylene composite bipolar plates with a 304 stainless steel by compression molding for PEM fuel cell. Int J Hydrogen Energy 36 7621-7627... 

Mathur RB, Dhakate SR, Gupta DK, Dhami TL, Aggarwal RK (2008) Effect of different carbon fillers on the properties of graphite composite bipolar plate. J Mater Process Tech 203 184-192... 

The analysis of carbon materials used as catalyst support, gas diffusion layer, and current collector and bipolar plates is performed in Chap. 7. A number of carbon materials including carbon blacks, nanotubes, nanofibers, and structured porous carbon materials are analyzed and compared as catalyst support in direct methanol fuel cells. Commercial and non-commercial gas diffusion layers are described along with the role of the mesoporous layer on the fuel cell performance. Finally, synthetic graphite and carbon composites used as current collector and bipolar plates are discussed, focusing on their mechanical and electrical properties and production costs. 

Dweiri and Sahari [16] investigated the electrical properties of fuel cell bipolar plates of carbon-based PP composites. Combinations of carbon black and graphite lead to composites with a higher electrical conductivity. 

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