Solid SOFC Seal

Science Daily had this development on solid oxide fuel cells:

Solid oxide fuel cells (SOFCs) have great potential for stationary and mobile applications. Stationary use ranges from residential applications to power plants. Mobile applications include power for ships at sea and in space, as well as for autos. In addition to electricity, when SOFCs are operated in reverse mode as solid oxide electrolyzer cells, pure hydrogen can be generated by splitting water.

But SOFCs have had a flaw – the integrity of the seals within and between power-producing units. "The seal problem is the biggest problem for commercialization of solid oxide fuel cells," said Peizhen (Kathy) Lu, assistant professor of materials science and engineering at Virginia Tech.

So she has invented a solution.

Composed of ceramic materials that can operate at temperatures as high as 1,800 degrees F (1,000 C), SOFCs use high temperature to separate oxygen ions from air. The ions pass through a crystal lattice and oxidize a fuel– usually a hydrocarbon. The chemical reaction produces electrons, which flow through an external circuit, creating electricity.

To produce enough energy for a particular application, SOFC modules are stacked together. Each module has air on one side and a fuel on the other side and produces electrons. Many modules are stacked together to produce enough power for specific applications. Each module's compartments must be sealed, and there must be seals between the modules in a stack so that air and fuel do not leak or mix, resulting in a loss of efficiency or internal combustion.

Lu has invented a new glass that can be used to seal the modules and the stack. The
self-healing seal glass will provide strength and long-term stability to the stack, she said.

[...]

"The invented glass seal materials are free of barium oxide, calcium oxide,
magnesia, and alkali oxides, and in addition contain almost imperceptibly low amounts of boron oxide," said Mike Miller senior licensing manager with Virginia Tech Intellectual Properties. "This is important because the seals must be both mechanically and chemically compatible with the different oxide and metallic cell components as they are repeatedly cycled between room and operating
temperatures,” said Miller.

- Brewskie

More Proof Why You Won't Need Platinum for Fuel Cells

(Editor's note: although blockquote works well for some bloggers, but its usage has proven finicky with Ghawar Guzzler. Excerpts from articles will be presented in italics until, otherwise noted.)

Researchers have grown arrays of carbon nanotubes which, under demonstration, may be capable of fulfilling the necessary role of catalyst with fuel cells - eliminating the need for exotic materials such as platinum; and they're cheaper and longer lasting, too boot.

Excerpts below include,

More than half the cost of fuel-cell stacks comes from platinum, according to the Department of Energy. "Fuel cells haven't been commercialized for larger-scale applications because platinum is too expensive," says Liming Dai, a materials-engineering professor at the University of Dayton, in Ohio, who led the work. "For electrodes, you need a cheaper material that still has a high performance."

Dai and his colleagues make electrodes by depositing the carbon-nanotube arrays on a composite film of polymer and carbon nanotubes. In a Science paper, the researchers show that using the material as a cathode gives four times higher current densities than do conventional platinum-coated electrodes. "There has been very limited success to finding a replacement for platinum, and [carbon nanotubes] could be one," says Prashant Kamat, a chemistry professor at the University of Notre Dame.

Carbon nanotubes, which are known to be electrically and mechanically robust, could overcome other issues that platinum faces. Carbon monoxide can stick to platinum's surface and make it less effective, Dai says. Also, platinum is not very durable, and its properties degrade over time. "Carbon nanotubes have long-term operational stability and do not suffer from carbon-monoxide poisoning," Dai says.

And...

To make the nanotube electrodes, Dai and his colleagues start with a compound containing carbon, nitrogen, and iron. They place this on a quartz substrate and heat it in the presence of ammonia, resulting in nitrogen-doped carbon nanotubes growing straight up from the surface. Then they oxidize the array to remove residual iron and transfer the array to a polymer film. Immersing the electrode in a potassium hydroxide electrolyte, the researchers found that it speeds up the cathode reaction of oxygen and electrons.

Meanwhile, others are working on different platinum substitutes. Kotaro Sasaki, who does fuel cell catalyst research at Brookhaven National Laboratory and his colleagues at Brookhaven are making atom-thick platinum films, which would use much less of the precious metal. Researchers at Monash University, in Australia, have made cathodes from a polymer called PEDOT. At Argonne National Laboratory, researchers have made nanotube arrays loaded with small quantities of platinum or iron.

- Brewskie