Investigation of a Manufacturing Process for Intermediate to Mass Production of Polymer/Graphite-Based Bipolar Plates for Proton Exchange Membrane Fuel Cells

At the recommendation of the ABAT accreditation committee, a new capstone design project class - Engineering Technology Project was introduced at our Engineering Technology Department in the spring semester of 2011. Students work in groups under direct faculty supervision on creative, challenging, open-ending projects proposed by the professor in the areaof renewable energy. Practical, hands-on experience is emphasized and analytical and designskills acquired in companion courses are integrated. These projects align with our state’s Third Frontier Fuel Cell Program commitment to accelerate the growth of fuel cell industry in the state, to investigate manufacturing processes and technologies, to adapt or modify existing components and systems that can reduce the cost of fuel cell systems, to address technical andcommercialization barriers and to demonstrate market readiness. Projects on which our studentsworked during the capstone design project class included the design and fabrication of a nine-cell, 50 cm 2 active area proton exchange membrane fuel cell (PEMFC) stack, a first ever successful demonstration of an automated assembly process of a PEMFC stack using robotic technology, design and fabrication of instrumentation for measuring physical properties for fuel cell components and the investigation of manufacturing processes for polymer/graphite-based bipolar plates for PEMFCs. As identified by the U.S. Department of Energy, one of the obstacles that remain to be resolved on the road to hydrogen economy is the cost of manufacturing fuel cells. A key component of the PEMFC stack represents the bipolar plates which account for 45% of the stack cost. Their functions in the fuel cell are to connect the cells electrically, to house the flow fields and uniformly distribute the reactant and oxidant gasses over the active area of the cells, to separate and prevent the reactant and oxidant gasses in adjacent cells from mixing with each other, to conduct and distribute the heat produced during the electrochemical reaction and to provide structural support to the cells. Bipolar plates must have good electrical and thermal conductivity, good mechanical characteristics, low gas permeability, good chemical stability (corrosion resistant), must be lightweight, easily formable and inexpensive. To meet these requirements, bipolar plates are usually made of graphite, coated or non-coated metals or frompolymer composites including graphite powder. The scope of the present work was to study the manufacturing process of bipolar plates for PEMFCs using compression molding of GP55-B (GrafTech Inc.) synthetic graphite used aselectrically conductive matrix and PLENCO 12114 phenol formaldehyde thermoset resin (Plenco Plastics Engineering Company) used as binder. We identified the optimum process characteristics including material composition, compression level, curing temperature, the mold design and performed property measurements on the obtained samples, including the measurement of bulk electrical conductivity using a four-point probe. The samples obtained demonstrated characteristics that exceed the requirements of the U.S. Department of Energy.