Battery design gets nanotube boost

NSCU have aligned silicon-coated carbon nanotubes like a layer of drinking straws.

NCSU team aligns silicon-coated carbon nanotubes like a layer of drinking straws. Photo credit: Horia Varlan

Researchers at North Carolina State University have created a new flexible nano-scaffold for rechargeable lithium-ion (Li-ion) batteries that could help make cell phone and electric car batteries last longer.

The research, published online in Advanced Materials, shows the potential of manufactured sheets of aligned carbon nanotubes coated with silicon, a material with a much higher energy storage capacity than the graphite composites typically used.

“Putting silicon into batteries can produce a huge increase in capacity, 10 times greater,” said Dr Philip Bradford, assistant professor of textile engineering, chemistry and science at NC State. “But adding silicon can also create 10 times the problems.”

One significant challenge in using silicon is that it swells as Li-ion batteries discharge. As the batteries cycle, silicon can break off from the electrode and float around instead of staying in place, making batteries less stable.

When the silicon-coated carbon nanotubes were aligned in one direction like a layer of drinking straws laid end to end, the structure allowed for controlled expansion so that the silicon is less prone to pulverisation.

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