Performance and durability of bipolar plate materials

Abstract

The bipolar plate is a multifunctional component of the fuel cell; its primary roles are to evenly distribute reactant gases whilst removing water from the cell. It must also transfer the heat of reaction away from the cell, provide electrical conductivity between adjacent cells and prevent mixing of the fuel and oxidant. An optimized bipolar plate must satisfy a number of materials and construction requirements, have good electrical and thermal conductivity, gas impermeability and corrosion resistance. It should also have minimal volume and weight and be inexpensive. Historically, graphite has been chosen as a compromise between these requirements, it has good electronic conductivity, excellent corrosion resistance and a low density. However, it is expensive, porous in nature, lacks mechanical strength and is not viable for volume production. Two basic types of bipolar plates have emerged as probable replacements for graphite, including composites fabricated from graphite or carbon powder and a polymer resin and metallic. Composite plates are lower cost, lower weight and mechanically stronger than graphite, and they can be fabricated using cost‐effective moulding techniques. Composites are less conductive than graphite, but recent developments have seen conductivities improve to levels approaching that of graphite. Metals, such as stainless steels and titanium, have high mechanical strength and are gas impermeable. Thus, thin bipolar plates can be manufactured using techniques amenable to mass production. The bulk resistivities of most metals are at least an order of magnitude lower than graphite; however, this can be more than offset by contact resistance due to surface oxide layers or corrosion products. The successful utilization of metallic bipolar plates in proton exchange fuel cells depends upon either the identification of metals or alloys with low contact resistance but good corrosion resistance, or the development of low‐cost conductive and protective coatings.

Influence of Expanded Graphite Particle Size on the Properties of Composite Bipolar Plates for Fuel Cell Application

“…The conventional materials for producing bipolar plates are graphite or metal. Graphite plates are preferred over metallic plates because of their high corrosion resistance and low density . However, its disadvantages include difficulties in machining and its brittleness. , Consequently, graphite bipolar plates require a thickness on the order of several millimeters, and cause the fuel cell stack to be massive and voluminous .…”

Development and Characterization of Expanded Graphite-Based Nanocomposite as Bipolar Plate for Polymer Electrolyte Membrane Fuel Cells (PEMFCs)

“…The conventional materials for producing the bipolar plate are graphite or metal. Graphite plates are preferred over the metallic plates because of their high corrosion resistance and lower density . On the other hand, disadvantages are difficulties in machining and its brittleness. , Because of this reason, a graphite-based bipolar plate requires a thickness of the order of several millimeters and causes the fuel cell stack to be massive and voluminous .…”

Formability Evaluation of Microchannels of Aluminum Bipolar Plate Stamped Under Pulsating Load

“…How ever, the formation of an oxidation layer on the surface of the steel plate over time degrades its electrical conductivity, thus reducing the efficiency of the fuel cell. Owing to such problem, one study chose an aluminum alloy that had excellent characteris tics such as high corrosion resistivity, low density (2.7g/cm3, one-third that of stainless steel and one-half that of titanium), low electrical resistivity (one-fifth that of stainless steel), high ther mal conductivity (8.5 times that of stainless steel), and low weight [4].…”