A Nickel Catalyst for Fuel Cells

THE MAGAZINE DEVOTED TO NICKEL AND ITS APPLICATIONS November 2005 Volume 21, Number 1

METALLIC NAOPOWDERS such as these could find applications as catalysts in batteries and fuel cells. Performance and costs are key.

Nearly 40% of the total cost of a fuel cell can be attributed to catalysts.

METALLIC VAPOURS are cooled by inert gases inside of a vacuum chamber such as this to produce nano-scale powders.

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Nickel-cobalt is seen as a low-cost substitute for platinum catalysts By Virginia Heffernan

Nickel Magazine, November 2005 -- The price of the catalyst is one of the main barriers to the development of affordable fuel cells. So anyone who can design a cheaper catalyst stands to make a significant contribution to the commercialization of the alternative energy technology.

California-based QuantumSphere Inc., a leading manufacturer of metallic nanopowders, claims to have done just that by developing a nickel-cobalt nanomaterial that could partially or fully replace platinum catalysts in a variety of battery and fuel cell applications.

Platinum, currently priced at about US$75 per gram in bulk, is about five times more expensive than QuantumSphere’s nickel-cobalt alloy, which sells for roughly US$15 per gram. As a result, QuantumSphere says, battery and fuel cell manufacturers would cut their costs by about 50% if they replaced platinum in catalysts with the new nanomaterial.

QuantumSphere recently had its results independently validated by DoppStein Enterprises Inc., a U.S.-based battery and fuel cell consulting firm.

Using the nickel-cobalt nanomaterial does require some sacrifice in performance. For instance, DoppStein found that if all the platinum on the cathode (7.7 micrograms per square centimetre) is replaced by nickel-cobalt, costs would drop by 90% and performance, compared with pure platinum, would decline 27%. Replace half the platinum, though, and costs drop by 43% with only a 10% reduction in performance.

"Nearly 40% of the total device cost can be attributed to catalysts in these systems, which tend to be prohibitively expensive for getting the device to commercialization," says Dr. Kimberly McGrath, the company’s director of fuel cell research. "If you couple the savings in cost [using the proprietary alloy] with the small sacrifice in performance, you have a huge benefit."

QuantumSphere is following up the preliminary results with a series of optimization experiments designed to coax the alloy to meet or exceed the activity of platinum-catalyzed cathodes. The current alloy blend is about 80% nickel and 20% cobalt, but compositions will vary depending on further testing and customer needs.

QuantumSphere started working on the nickel-cobalt nanomaterial after it was approached by a leading battery consultant who wanted a less expensive alternative to platinum in battery catalysts, says the company’s president, Kevin Maloney.

"The trends and drivers for us are the large companies that have come to us and disclosed some of the challenges they are having and the solutions with which they’d like to be provided," he says.

The technology required to make the nickel-cobalt nanomaterial, gas phase condensation, has been around for about 30 years. But by adapting the process to control the particle size and the thickness of the oxide shell on the particle, QuantumSphere’s scientists can do what once seemed impossible: grow a uniform distribution of the required particle size.

This breakthrough allowed QuantumSphere to develop a fully automated production line that can be scaled to meet demand. Manufacturing capacity has grown from a few grams per day to several pounds per day, or thousands of pounds per year.

The gas phase condensation takes place inside a vacuum chamber where metal wire is melted at high temperatures. As the metal vaporizes, the vapor is cooled by inert gas and condenses into droplets of liquid metal. The characteristics of the particles can be changed by adjusting the chamber pressure, temperature and gas flow.

The surface area of resulting nickel-cobalt nanomaterial is so high in proportion to the particle size that virtually every particle in the atom can react.

"At the nano-scale, scientists have really created a new periodic table, if you will," says Maloney. "These materials are much more energetic; you just don’t get that performance at the micron scale."

Virginia Heffernan is a Toronto-based science writer.

PHOTOS: QuantumSphere Inc.

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