View Under The Hood:

PolyFuel drops in with hydro-carbon based portable fuel cell

By Bernard Cole
iApplianceWeb
(04/13/05, 12:45:42 AM GMT)

Mountain View, Ca. -- PolyFuel Inc., a spin-off from the Stanford Research Institute -- which for a year has been focused on fuel cells based on natural hydrocarbons rather than synthetic and highly volatile fluorocarbon chemistry -- has come up with what it thinks is yet another better idea.

It has just announced what is says is the  first hydrocarbon fuel cell membrane that is a "drop-in" replacement for fluorocarbon membranes in existing fuel cell membrane electrode assembly (MEA) manufacturing processes. Last year, PolyFuel announced the world's first commercial hydrocarbon-based membrane for portable direct methanol fuel cells (DMFC).

Jim Balcom, PolyFuel's president and CEO said the most immediate impact of this new development will be on the "micro-portable" fuel cell market in portable and mobile devices.

“Fuel cell system costs are already in the right range, consumers are clamoring for longer run times on their portable devices,” he said,”and manufacturers are building increasingly power-hungry applications such as wireless connectivity in notebooks, and full-motion video into cell phones.

 “Hydrocarbon membranes offer several substantive advantages over fluorocarbon membranes, particularly in reducing the size, weight and cost and increasing the runtime of portable fuel cell systems. However they also, until today, have typically required different approaches in manufacturing than those used to fabricate fuel cells from fluorocarbon membranes.”

With the new drop-in membrane, that is no longer the case.

"Fuel cell manufacturers can now utilize our new membrane as a drop-in replacement for Nafion or other fluorocarbon membranes in their existing MEA fabrication processes," he said.

A Brief History of Fuel Cells

According to Balcom, widespread adoption of fuel cells, and their long-term commercial viability, depends heavily on their rate of adoption in the power-hungry portable market. "Of the several critical problems to be solved, manufacturability remains high on the list.”

While not yet commercially available, he said, portable fuel cells are the subject of increasingly widespread research and development activity, with huge investments being made by a significant number of companies, both in Japan and the United States.

Virtually all of that investment has revolved around fuel cell membranes based upon fluorocarbon technology, pioneered by DuPont with the development of their Nafion material in the 1960s, which, although not able to deliver the performance required for commercially-viable portable fuel cells, has, historically speaking, been the only game in town.

Fuel cell membranes -- which resemble sheets of cellophane -- are literally the heart of a fuel cell. As a result of their uniquely-engineered structure and

chemical composition, they are able to produce electricity by stripping electrons from fuel molecules.

The only byproduct is water, and for portable fuel cells that use methanol as a fuel, carbon dioxide. During the manufacture of such a cell, a multi-layer

sandwich of membrane and other materials -- called an MEA, for "membrane-electrode assembly" -- must be fabricated.

The MEA acts as a rigid barrier inside the fuel cell separating the wet fuel on one side, and the air on the other, while simultaneously keeping the membrane in contact with both. An MEA in a fuel cell intended for a cell phone would be the size of a business card, and about as thick as a credit card.

Hot Bondable Hydrocarbon Is the Answer

Because of the innate plastic characteristics of Nafion and other fluorocarbon membranes, they soften at relatively low temperatures, which has allowed the development of MEA fabrication techniques where the membrane is "hot bonded" to the adjacent components.

Hydrocarbon membranes, which are typically stronger and more durable, have not lent themselves to this technique, as they don't soften at the same low temperatures as fluorocarbon membranes.

However, PolyFuel's new "hot-bondable" membrane, said Balcom, permits manufacturers to effectively "drop in" the more desirable hydrocarbon membrane into fabrication processes originally designed for Nafion.

"This is an important announcement for PolyFuel and a significant development for the industry," said John Appleby, of Texas A&M University's Center for Electrochemical Systems & Hydrogen Research, and author of The Fuel Cell Handbook, 4th Edition. "Substantial investment and momentum have built up around developing high-volume, low-cost MEA fabrication processes, and having a hydrocarbon membrane that can simply be substituted in for fluorocarbon will garner a high degree of interest."

How PolyFuel Did It

PolyFuel's original breakthrough hydrocarbon membrane, as well as and this new hot-bondable version, said Balcom, have been engineered  specifically for portable fuel cell applications. The hydrocarbon polymer is designed to be uniquely durable in the presence of methanol, the most commonly used fuel for portable fuel cells.

“Additionally, the membrane properties have been optimized for high performance and high fuel efficiency,” he said. “This allows portable fuel cell manufacturers to design fuel cell systems that are smaller, lighter and less expensive -- while at the same time being more robust and delivering longer runtimes -- compared to systems incorporating conventional fluorocarbon materials such as Nafion.”

The hot-bondable version results from a proprietary surface modification. With this modification, the membrane behaves in a fashion similar to Nafion during the bonding or MEA fabrication process, while still retaining the underlying advantages of the original PolyFuel hydrocarbon membrane.

Focusing on Micro-Power Fuel Cells

Where most fluorocarbon fuel cell providers are focusing on higher power big system applications, Balcom believes the future of hydrocarbon-based drop in replacements is in the mobile and portable electronics markets.

Higher power applications, such as automotive use, he said, have a trillion-dollar global infrastructure that will be required to distribute hydrogen fuel as widely as gasoline is today. Also lifetimes are still too short and costs per kilowatt are still too high.

The potential is much greater, said Balcom, in the "micro-portable" fuel cell market particularly with high performance hydrocarbon membranes. Not only is the demand there, the fuel infrastructure is trivial.

Such fuel cartridges, resembling disposable cigarette lighters, will, he believes, in the not-too-distant future, be available in every convenience store and market – which explains why companies such as BIC and Tokai are very active in methanol fuel cartridge development.

"Fuel cells are the only viable technology for portable devices to deliver all of the capabilities consumers desire, (and Moore's Law is making possible)," said Balcom, pointing to estimates based on input from Frost & Sullivan and ABI Research, the market for micro-power direct methanol fuel cells will be over 140 million units in 2012.

PolyFuel's first DMFC hydrocarbon membrane is actively being evaluated by virtually all of the leading fuel cell manufacturers worldwide, and is in use in pilot projects at many, said Balcom.

To learn more, go to www.polyfuel.com.