Hubei (China) - A new form of non-alkali membrane used in fuel cells could allow expensive and rare platinum to be replaced with nickel. If true, the market could soon be filled with much less expensive fuel cells and a changing attitude toward fuel economy in automobiles as fuel cells can be more efficient than internal combustion engines.





Traditional fuel cell



Fuel cells are composed of two metal plates with a membrane between them, with one side traditionally being platinum (or some other "noble metal"). When a fuel source, commonly methanol, is passed along the platinum side of the plate, it acts as a catalyst breaking down the fuel and it's hydrogen atoms into one proton and one electron.



The proton then passes through the membrane to react with oxygen on the other side to create water. The electron continues along the metal surface, serving as the source for created electricity. Heat is also generated, though not nearly as much as burning the fuel in an internal combustion engine.



Platinum has been used because the membrane material (typically a polymer electrolyte called Nafion) creates a highly corrosive acidic environment, and platinum remains completely stable when exposed to it.



The new fuel cell uses a different type of construction and membrane which is not acidic, allowing far less expensive nickel to be used as the catalyst in platinum's place.





New fuel cell



A Chinese team led by Lin Zhuang at Wuhan University has created a new polymer electrolyte fuel cell (PEFC) comprised of hydroxide ion-conductive polymer, quaternary ammonium polysulphone, an alkaline electrolyte and nonprecious metals such as chromium-decorated nickel and silver. Their work is published in Proceedings of the National Academy of Sciences.



The team has also modified the catalyzing surface of nickel with chromium, a toxic substance recently added to the banned list of hazardous materials prohibited for use in the auto industry (at least without adequate ventilation during chrome plating processes as some sources are being grandfathered into place). This plating reduces its susceptibility to oxidation over time, extending the "efficiency life" of the fuel cell.



Basically, the new fuel cell is not as corrosive as the old one internally. And because of this, and also because of the way the surface of the chromium-decorated nickel has been altered, the fuel which passes into the system can be broken down without degradation over time.



According to the paper's abstract, the new design "remains completely free from noble metal catalysts in both the positive and negative electrodes," which makes it much less expensive by using cheaper metals as catalysts. In addition, the discovery "represents an important advancement in the reserach and development of fuel cells."

A working prototype of the new fuel cell delivers 50 milliwatts per cm² at 60 Celsius. "The power output is still lower than that of fuel cells using platinum, but such a comparison may not be appropriate because platinum fuel cells have been studied and optimised for decades," Zhuang says. In addition, most previous PEFC fuel cell solutions broke down above 40 Celsius making them not usable for most commercial applications (like cars).

While this new invention shows promise, it is not yet ready for mass production. However, according to Zhuang, this may only be a matter of time.





Attractive power source



Fuel cells have already been considered as a possible replacement for the internal combustion engine, even with their premium expense and low operational life. They utilize fuel more efficiently through the fuel cell conversion process than by burning it inside an engine. The fuel cell also produces less gaseous pollution and the automobiles essentially become zero-emission vehicles, generating mostly heat and water along with some fuel waste which can be recouped.



Fuel cells have not been readily adopted because of their high cost, largely due to platinum and other noble metals employed. They also have short operational life spans due to their construction. One crack can render the entire fuel cell completely dead.



According to Dr. Jery Woodall, Purdue processor who has devoted a large portion of his academic career to discovering new ways to generate power from hydrogen fuel sources including one he created called AlGal75 (and AlGal80), has said that fuel efficiencies in excess of 75% have already been achieved with platinum-based fuel cells. Though, these typically only have operational lifetimes of 2000 hours or so, and they cost a "few million dollars."



Typical fuel cell efficiencies are around 50%, which is roughly equivalent to diesel internal combustion engines, and about 10% to 15% more efficient than gasoline internal combustion engines.