Stanford University researchers have discovered a way to increase battery life tenfold by using silicon nanowires.

Stanford University researchers have made a discovery that could
signal the arrival of laptop batteries that last more than a day on a
single charge.

The researchers have found a way to use silicon nanowires to give rechargeable lithium ion batteries–used
in laptops, iPods, video cameras, and mobile phones–as much as 10
times more charge. 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.

"It’s not a small improvement," Cui said. "It’s a revolutionary development."

Citing a research paper they wrote, published in Nature Nanotechnology,
Cui said the increased battery capacity was made possible though 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 "the highest theoretical charge
capacity" according to Cui’s paper, 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.

Cui and his colleagues looked at this old problem and overcame it by
constructing a new type of silicon nanowire anode. In Cui’s 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.

Cui said there are a few barriers to commercializing the technology.

"We are working on scaling up and evaluating the cost of our
technology," Cui said. "There are no roadblocks for either of these."

Cui 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.

Via C-Net