Atofina membrane work seeks to drive down fuel cells cost
Staff -- Purchasing, 9/2/2004 2:00:00 AM
Atofina, the chemicals unit of the Paris-based oil giant Total, is collaborating with several corporate and university partners in the U.S. to come up with inexpensive polymer membranes for fuel cells. Reducing the cost of components of fuel cells, which convert hydrogen and oxygen into electricity, is a key research objective for proponents of a future hydrogen economy. Atofina reports significant progress in the membrane project, which is part of a fuel cell program funded by the Department of Energy.
Fuel cell membranes, which make contact with electrolytes and separate the anode and cathode compartments, must be able to conduct hydrogen ions across their surface boundaries. Right now, the most common fuel cell membranes are composed of perfluorosulfonic acid (PFSA) polymers such as DuPont's Nafion. Existing PFSA membranes are excellent ionic conductors but are considered too expensive for future large-scale fuel cell applications such as powering automobiles.
They also cannot withstand long-term exposure to the high temperatures (around 120°C) at which fuel cells operate most efficiently. Atofina hopes to adapt its much lower priced and more rugged polyvinylidene fluoride (PVDF) resin, tradenamed Kynar, for use in fuel cell membranes.
In its pure state, however, PVDF lacks two essential requirements for a fuel cell membrane: it is not hydrophilic (water absorbing) or ionically conductive. But in its fuel cell research, Atofina has found a way to overcome this deficit by making homogeneous alloys of its Kynar PVDF with an undisclosed polyelectrolyte (an ionically conductive polymer).
Membranes made from these alloys "have excellent physical properties and chemical resistance, due to the Kynar, and very good proton conduction and water absorption, due to the polyelectrolyte," says Scott Gaboury, manager for coatings and films at the research center of Atofina Chemicals Inc. in King of Prussia, Pa.
Atofina stated that its alloy membranes have a hydrogen ion permeability about a third that of Nafion, a property which it described as "very desirable" for potential fuel cell applications.
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