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bobgnote · Aug 25, 2012

Here's a hot story:

http://phys.org/news/2012-08-ibn-superior-fuel-cell-material.html

Using a mixture of gold, copper and platinum nanoparticles, IBN researchers have developed a more powerful and longer lasting fuel cell material. This breakthrough was published recently in leading journal, Energy and Environmental Science.

Read more at: http://phys.org/news/2012-08-ibn-superior-fuel-cell-material.html#jCp
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Current commercially available fuel cells use platinum nanoparticles as the catalyst to speed up the chemical reaction because platinum is the only metal that can resist the highly acidic conditions inside such a cell. However, the widespread use of fuel cells has been impeded by the high cost of platinum and its low stability. To overcome this limitation, a team of researchers led by IBN Executive Director Professor Jackie Y. Ying has discovered that by replacing the central part of the catalyst with gold and copper alloy and leaving just the outer layer in platinum, the new hybrid material can provide five times higher activity and much greater stability than the commercial platinum catalyst.

With further optimization, it would be possible to further increase the material's catalytic properties. IBN's new nanocomposite material can produce at least 0.571 amperes of electric current per milligram of platinum, compared to 0.109 amperes per milligram of platinum for commercial platinum catalysts. This is also the first time that a catalyst has been shown to enhance both the stability and activity for the fuel cell reaction with a significantly reduced platinum content. To make this catalyst more active than the commercial platinum catalyst, the researchers have designed the core of the nanocrsytalline material to be a gold-copper alloy, which has slightly smaller lattice spacing than the platinum coating on the nanocrystal's surface.

This creates a compressive strain on the surface platinum atoms, making the platinum more active in the rate-limiting step of oxygen reduction reaction for the fuel cell. Replacing the core of the nanoparticle with the less expensive gold-copper alloy cuts down the usage of platinum, a highly expensive noble metal. Professor Ying said, "A key research focus at IBN is to develop green energy technologies that can lead to greater efficiency and environmental sustainability. More active and less costly than conventional platinum catalysts, our new nanocomposite system has enabled us to significantly advance fuel cell development and make the technology more practical for industrial applications."

Read more at: http://phys.org/news/2012-08-ibn-superior-fuel-cell-material.html#jCp
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http://phys.org/tags/nanocomposite/

waltky · Dec 6, 2012

Future batteries may rely on liquid metals...

Liquid metal promise for future batteries
5 December 2012 - Inside the Sadoway Lab's liquid metal battery workshop

Batteries have come a long way since Italian professor Alessandro Volta invented the first iteration some 200 years ago. Even so, there are few candidate battery types that are suitable for storing energy on large scales - within an electrical power grid, for example. Given that electricity is generally not stored, the grid has to carefully balance consumer demand for electricity with the amount being supplied by generators. Grid-scale energy storage - sequestering electricity and then releasing it on demand - would be highly desirable. But any technology designed for such a purpose would have to deal with daunting amounts of power, be very cheap and have a long service lifetime.

Prof Donald Sadoway, from the Massachusetts Institute of Technology (MIT) in Cambridge, US, has been working on one technology designed to fulfil these requirements - liquid metal batteries. The effort is now approaching a critical juncture. Sadoway has been working to scale up the technology through his company Ambri and is aiming for a commercial prototype to be ready by 2014. "At least 18 months from now, we'll have something we can put in the hands of an independent assessor," Prof Sadoway told BBC News. "We want to make sure we've got something that's durable and will perform to specification. This is a very tough market to get into. "We can't afford to have a failure because something wasn't quite right. That could tarnish the image of the technology to the point where it would be set back irreparably."

Most of the hurdles encountered during the scale-up are related to manufacturing issues; Donald Sadoway says the basic chemistry is scaling "beautifully". A conventional dry-cell battery uses two electrodes separated by an electrolyte. But building a giant battery using dry-cell technology would require thousands of individual cells - about the size of a soft drinks can - to be strung together in a massive installation. Prof Sadoway's concept relies on similar principles, but the key components are liquid. A molten-salt electrolyte is sandwiched between two liquid metal electrodes. A dense positive electrode lies at the bottom of the battery, while a low-density negative electrode floats atop the electrolyte. The difference in composition between the two liquid metals gives rise to a voltage.

The MIT electrochemist thinks it is possible to build giant batteries using 50-100 fewer individual cells this way than would be possible with a conventional battery array, reducing cost and complexity. It's an idea that has attracted some $15m of investment from Bill Gates, Total and Khosla Ventures, run by Sun Microsystems co-founder Vinod Khosla. The most basic version of the battery used magnesium for the top layer and antimony for the bottom layer. Prof Sadoway calls this iteration "generation zero". The work on campus at MIT has since moved on: "We now have chemistries that we're calling fourth generation, fifth generation," Prof Sadoway explains.

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