**Nitrided Metallic Bipolar Plates**

**A Proposal in Response to DOE Solicitation DE-PS36-06GO96018**

**Topic 4A: Bipolar Plates**

**P.I.: Michael P. Brady, Oak Ridge National Laboratory**

**Project Director: Timothy R. Armstrong, Oak Ridge National
Laboratory**

Co PI's: K.L. More, P.F. Tortorelli and H.M. Meyer, III (Oak Ridge
National Laboratory); R. Bernard and D. Connor (GenCell Corp); J
Rakowski (Allegheny Ludlum Inc.); M. Wilson, F. Garzon, R. Borup (Los
Alamos National Laboratory); J.A. Turner, H. Wang (National Renewable
Energy Laboratory); and D. Gervasio and A.N. Mada Kannan (Arizona State
University)

Proton exchange membrane fuel cells (PEMFC) are of great interest for
power generation due to their high efficiency and near-zero emissions.
The bipolar plate is a key PEMFC component that serves to connect
individual fuel cells in a stack to achieve a useful voltage, as well as
to separate and distribute hydrogen and air gas flows. Bipolar plates
are a significant fraction of the cost, and constitute the dominant
weight and volume of the fuel cell stack. The current lack of a cost and
performance viable bipolar plate material is a major barrier to
widespread commercialization of PEMFC technology. Metallic alloys would
be ideal as bipolar plates because they are amenable to
low-cost/high-volume manufacturing methods such as stamping, and can be
made in thin foil form (≤ 0.1 mm thick) to achieve high power densities.
However, they also suffer from high interfacial contact resistance (ICR)
and inadequate corrosion resistance in the highly aggressive PEMFC
environment.

The goal of the proposed effort is to scale up and demonstrate the
technological and economic viability of thin (≤ ∼ 0.1 mm) stamped
metallic bipolar plates protected by a thermal (gas) nitridation surface
treatment. In this approach, an electrically-conductive and
corrosion-resistant Cr-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 successful
demonstration of this technology would represent a major step towards
the commercialization of PEMFC technology for automotive applications
due to the high power densities achievable with thin metallic bipolar
plates, and the low-cost/high-volume manufacture capability of stamping
to introduce flow fields

To accomplish this, a multi-organization national
laboratory-university-industry team has been assembled. Oak Ridge
National Laboratory (ORNL) will lead efforts for optimization of an
inexpensive Fe-Cr base alloy composition and nitridation conditions to
meet DOE bipolar plate performance and cost goals, with supporting
characterization studies of corrosion resistance, electrical properties,
and single cell behavior performed by National Renewable Energy
Laboratory (NREL) and Arizona State University (ASU). Fuel cell stack
testing will be conducted by Los Alamos National Laboratory (LANL). To
establish the basis for commercial viability and availability, an alloy
producer, Allegheny Ludlum Corp. will cast and manufacture developmental
alloys into light gage alloy foil suitable for stamping. A metal bipolar
plate manufacturer, GenCell Corp, will stamp the alloy foil into bipolar
plates for subsequent nitridation and fuel cell stack testing. By
teaming with an alloy manufacturer and a metallic bipolar plate
component supplier, the basis will be established to make the technology
developed under this program commercially available to all interested
fuel cell developers and end users.