Low-Cost Manufacturing of Sheet Molding Compound Bipolar Plates for PEM Fuel Cells

The fluid-flow field plate, or bipolar plate, is known to significantly impact the performance, durability, and cost of a fuel cell system. Conventional methods of fabricating bipolar plates require the engraving or milling of flow channels into the surface of metal plates. As a consequence, the bipolar plate is one of the most costly components of a proton-exchange-membrane (PEM) fuel cell, due to high machining costs. In addition, long-term corrosion is a major concern for metal plates. Composite bipolar plate are an option, but conventional composites are typically difficult to process, expensive, or not sufficiently conductive. This project will develop a low-cost, mass-production process for manufacturing flexible, graphite-based, sheet-molding-compound (SMC) bipolar plates. Compared to metal and other current composite bipolar plate technologies, flexible graphite SMC will have the advantages of high conductivity, low weight, small volume (thin plate), high resistance to gas permeability, high corrosion resistance, and mass production capability, resulting in lower fuel cell cost and improved system reliability. Phase I will demonstrate the feasibility of producing bipolar plates by using continuous in-line lamination and embossing of SMC. In particular, Phase I will design and construct a roll-to-roll sheet molding compound fabrication apparatus, fabricate the SMC bipolar plates, and characterize both the bipolar plates and PEM fuel cells using these plates. Commercial Applications and Other Benefits as described by the awardee: Highly conductive sheet molding compound (SMC) materials should find use as bipolar plates in PEM fuel cells for automotive/transportation, residential/stationary, and portable/micro fuel cells. Using the automotive market as an example, an automotive fuel cell stack could use up to 190 pounds of thermoset composite per vehicle. If 50% of all the new cars and trucks used fuel cell-power, a 1.5 billion pound composite market would be created. Other applications for conductive SMC include electromagnetic interference (EMI) shielding, resistive heating, thermoelectric-energy generation, heat dissipation for microelectronic packaging, and electrode materials for battery applications.