Silicon Nanowires To Increase Battery Life Tenfold

Joseph Lopez

Thursday, May 08, 2008

Researchers at Stanford University have found a way to use silicon nanowires to give rechargeable lithium-ion batteries as much as 10 times more capacity. This potentially could give a conventional battery-powered laptop 40 hours of battery life, rather than 4 hours.

The new batteries were developed by assistant professor Yi Cui and colleagues at Stanford University's Department of Materials Science and Engineering.

The battery capacity was increased using a new type of anode that utilizes silicon nanowires. Traditional lithium-ion batteries use graphite as the anode. This limits the amount of lithium--which holds the charge--that can be held in the anode, and it therefore limits battery life.

Silicon anodes have the highest theoretical charge capacity, but they expand when charging and shrink during use: a cycle that causes the silicon to be pulverized, degrading the performance of the battery. For 30 years, this dead end stumped researchers who poured their battery life-extending energy into improving graphite-based anodes.

This problem was overcome by constructing a new type of silicon nanowire anode. In this particular anode, the lithium is stored in a forest of tiny silicon nanowires, each with a diameter that is a thousandth of the thickness of a sheet of paper. The nanowires inflate to four times their normal size as they soak up lithium, but unlike previous silicon anodes, they do not fracture.
Fortunately there are few barriers to commercializing this technology.
Researchers at Stanford University are working on scaling up and evaluating the cost of this technology.

Assistant professor, Yi Cui, at Stanford's Department of Materials Science and Engineering has filed a patent on the technology and is considering formation of a company or an agreement with a battery manufacturer. He expects the battery to be commercialized and available within "several years," pending testing.

[Stanford News Service]

Silicon Nanowires To Increase Battery Life Tenfold

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