Nitrided Metallic Bipolar Plates

Conference · Tue Jan 01 00:00:00 EST 2008

OSTI ID:979095

Brady, Michael P ^[1]; Tortorelli, Peter F ^[1]; Pihl, Josh A ^[1]; Toops, Todd J ^[1]; More, Karren Leslie ^[1]; Meyer, III, Harry M ^[1]; Vitek, John Michael ^[1]; Wang, Heli ^[2]; Turner, John ^[2]; Wilson, Mahlon ^[3]; Garzon, Fernando ^[3]; Rockward, Tommy ^[3]; Connors, Dan ^[4]; Rakowski, Jim ^[5]; Gervasio, Don ^[6]

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1. ORNL
2. National Renewable Energy Laboratory (NREL)
3. Los Alamos National Laboratory (LANL)
4. GenCell Corp
5. Allegheny Ludlum
6. Arizona State University

The objectives are: (1) Develop and optimize stainless steel alloys amenable to formation of a protective Cr-nitride surface by gas nitridation, at a sufficiently low cost to meet DOE targets and with sufficient ductility to permit manufacture by stamping. (2) Demonstrate capability of nitridation to yield high-quality stainless steel bipolar plates from thin stamped alloy foils (no significant stamped foil warping or embrittlement). (3) Demonstrate single-cell fuel cell performance of stamped and nitrided alloy foils equivalent to that of machined graphite plates of the same flow-field design ({approx}750-1,000 h, cyclic conditions, to include quantification of metal ion contamination of the membrane electrode assembly [MEA] and contact resistance increase attributable to the bipolar plates). (4) Demonstrate potential for adoption in automotive fuel cell stacks. Thin stamped metallic bipolar plates offer the potential for (1) significantly lower cost than currently-used machined graphite bipolar plates, (2) reduced weight/volume, and (3) better performance and amenability to high volume manufacture than developmental polymer/carbon fiber and graphite composite bipolar plates. However, most metals exhibit inadequate corrosion resistance in proton exchange membrane fuel cell (PEMFC) environments. This behavior leads to high electrical resistance due to the formation of surface oxides and/or contamination of the MEA by metallic ions, both of which can significantly degrade fuel cell performance. Metal nitrides offer electrical conductivities up to an order of magnitude greater than that of graphite and are highly corrosion resistant. Unfortunately, most conventional coating methods (for metal nitrides) are too expensive for PEMFC stack commercialization or tend to leave pinhole defects, which result in accelerated local corrosion and unacceptable performance.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Shared Research Equipment Collaborative Research Center
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 979095
• Resource Relation: Conference: Annual Merit Review and Peer Evaluation DOE Hydrogen Fuel Cell Infrastructure Program, Arlington, VA, USA, 20080609, 20080613
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
36 MATERIALS SCIENCE
ALLOYS
AUTOMOTIVE FUELS
COATINGS
CONTAMINATION
CORROSION
CORROSION RESISTANCE
DEFECTS
DUCTILITY
ELECTRIC CONDUCTIVITY
ELECTRODES
EMBRITTLEMENT
FUEL CELLS
GRAPHITE
HYDROGEN FUEL CELLS
MEMBRANES
NITRIDATION
NITRIDES
OXIDES
PROTON EXCHANGE MEMBRANE FUEL CELLS
STAINLESS STEELS