10 Times the Charge of Existing Batteries

The new version, developed through research led by Yi Cui, assistant professor of materials science and engineering at Stanford University, produces 10 times the amount of electricity of existing lithium-ion batteries. A laptop that now runs on battery for two hours could operate for 20 hours.

The greatly expanded storage capacity could make Li-ion batteries attractive to electric car manufacturers. Cui suggested that they could also be used in homes or offices to store electricity generated by rooftop solar panels. "Given the mature infrastructure behind silicon, this new technology can be pushed to real life quickly," Cui said.

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 as the lithium is drawn out of the silicon. This expand/shrink cycle typically causes the silicon 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.

For their experiments, Chan grew the nanowires on a stainless steel substrate, providing an excellent electrical connection.

COMPAMED.de; Source: Stanford University