DOE Awards Follow-On Funding for Metallic Bipolar PEM Fuel Cells

8 November 2006

Protective chromium-nitride surface layer. Click to enlarge.

The Department of Energy has awarded $4.5 million to Oak Ridge National Laboratory (ORNL) and its partners to further the development of nitrided metallic bipolar plates for automotive PEM fuel cells. The award is a follow-on to an earlier $1.65-million project designed to demonstrate the potential for metallic bipolar plates to meet 5,000-hour durability goals at a cost of <$6/kW.

The first project ended in September 2006; the follow-on will begin in 2007, and last for two years.

In addition to ORNL, which is developing the nitridation surface treatment, partners include the National Renewable Energy Laboratory (NREL); Los Alamos National Laboratory; GenCell, makers of bipolar-plate fuel cells; Arizona State University; and Allegheny Ludlum Corp.

Metallic bipolar plates are an alternative to carbon-composite bipolar plates and are preferred by many automobile companies. The key issue with metallic plates, however, is developing corrosion-resistant and low-contact-resistant materials while offering the potential for low-cost production.

The goal of the follow-on project is to scale up and to demonstrate the technological and economic viability of thin-stamped metallic bipolar plates protected by a thermally nitrided surface treatment.

In this approach, an electrically-conductive and corrosion-resistant chromium-nitride surface layer is formed on the bipolar plate component by heating a specially designed bipolar plate alloy to high temperatures in a nitrogen-containing environment.

The process results in a surface conversion, and is not a deposited coating. The high process temperature favors the reaction of all metal surfaces, eliminating pin-hole defects. The process is also amenable to complex geometries, such as those in the bipolar plate. This allows the plates to be stamped and then nitrided—an established and low-cost approach.

The project work will include optimization of an inexpensive iron-chromium base alloy composition and nitridation process; characterization of the bipolar plates; and demonstration of the optimized bipolar plate stamping and nitridation processes and subsequent plate testing in a fuel cell stack.

GenCell bipolar plate cell.

GenCell has developed a proprietary sheet metal bipolar separator plate, current collector and electrodes—the discrete components of a fuel cell. The GenCell product nests sheet metal bipolar plates with thin walls and high surface area.

The company will receive $1.25 million of the grant to advance these stamped metallic bipolar plates and to provide the plate and stack architecture designed to meet cost and weight targets set by the DOE.

Resources:

• Fuel Cell based Power-Sources for Airplanes (ASU)

• DOE FY 2006 Merit Review & Peer Evaluation Report, Summary of Fuel Cells Subprogram

• Cost-Effective Surface Modification For Metallic Bipolar Plates

• GenCell’s Metallic Bipolar Plates for PEMFC