The key to developing longer lasting batteries in cell phones and electric cars could lie in silicon.
Researchers at North Carolina State University have manufactured carbon nanotubes coated with silicon, a material that has a much higher capacity to store energy than the graphite composites used in lithium ion batteries.
“There’s a huge demand for batteries for cell phones and electric vehicles, which need higher energy capacity for longer driving distances between charges,” said Xiangwu Zhang, associate professor of textile engineering, chemistry and science at N.C. State.
Zhang said that while the researchers believe the carbon nanotube scaffolding holds the potential to change the battery industry, technical aspects still need to be worked out. But he added that the manufacturing process used by N.C. State researchers is scalable and could be adapted to commercial production.
The N.C. State research was published online in Advanced Materials.
Putting silicon into batteries can boost the energy capacity as much as 10 times greater, said said Philip Bradford, assistant professor of textile engineering, chemistry and science at N.C. State.
“But adding silicon can also create 10 times the problems,” he said.
Silicon swells as lithium ion batteries discharge. When this happens, silicon can break off from the electrode instead of staying in place. This “pulverization” makes the batteries less stable.
Zhang said that 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 making the silicon less prone to pulverization.
The research was supported by the Donors to the American Chemical Society Petroleum Research Fund.