Stanford Researchers Increase Battery Life by 10X
December 20, 2007 11:56 AM | Technology | Comments (0)
| Stanford researchers have found a way to use silicon nanowires to produces 10 times the amount of electricity of existing lithium-ion, known as Li-ion, batteries that power laptops, iPods, video cameras, cell phones, and countless other devices. A laptop that now runs on battery for two hours could operate for 20 hours. According to Yi Cui, assistant professor of materials science and engineering, "It's not a small improvement...It's a revolutionary development." The breakthrough technology was published online December 16 in Nature Nanotechnology in a paper titled "High-performance lithium battery anodes using silicon nanowires". The paper is written by Cui, his graduate chemistry student Candace Chan and five others. The 10 fold expanded storage capacity could make Li-ion batteries attractive to electric car manufacturers and be used in homes or offices to store electricity generated by rooftop solar panels. |  |
The electrical storage capacity of a Li-ion battery is limited by how much lithium can be held in the battery's anode, which is typically made of carbon. Silicon has a much higher capacity than carbon, but also has a drawback.
Silicon placed in a battery swells as it absorbs positively charged lithium atoms during charging, then shrinks during use (i.e., when playing your iPod) as the lithium is drawn out of the silicon. This expand/shrink cycle typically causes the silicon (often in the form of particles or a thin film) to pulverize, degrading the performance of the battery.
Cui's battery gets around this problem with nanotechnology. The lithium is stored in a forest of tiny silicon nanowires, each with a diameter one-thousandth the thickness of a sheet of paper. The nanowires inflate four times their normal size as they soak up lithium. But, unlike other silicon shapes, they do not fracture.
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