Lightweight and Corrosion Resistant Metal Bipolar Plates for PEM Fuel Cells 1999-01-2614
The fuel cell is a high-efficiency, low-emission electro-chemical device adaptable to a host of power generation applications. A bipolar plate is used to feed reactants to the fuel cell electrodes and to collect current. The bipolar plates for proton exchange membrane fuel cells (PEMFCs) have been traditionally fabricated from graphite, owing to its high electrical conductivity and high corrosion resistance. However, the large mass and volume of graphite make it an unlikely choice for automotive fuel cell bipolar plates. The use of lightweight metals such as aluminum is attractive, due to its low mass and volume, low-cost, and ease of manufacturing. Unfortunately, high corrosion resistance and electrical conductivity requirements for fuel cell components preclude uncoated aluminum.
Physical Sciences Inc. (PSI) is currently developing low cost alloy coatings for aluminum that possess high corrosion resistance and high electrical conductivity; required attributes for fuel cell applications. We have fabricated coated aluminum bipolar plates for PEMFC testing. Our preliminary results show comparable operating performance from coated aluminum and traditional graphite bipolar plates. Current development efforts include novel electrolytic alloy coatings, and conductive polymer coatings for controlled corrosion and reduction of corrosion byproducts, which may be deleterious to ion exchange membranes and electrodes. Careful selection of alloy coatings and their constituents offer the ability to reduce or control the electro-chemical corrosion potential and corresponding corrosion rate of the alloy coating.