Use of Kevlar Promises Thinner, Safer Batteries

A new battery technology developed by researchers at the University of Michigan could prevent short-circuits and fires with the help of ultra-thin Kevlar fibers. Such battery failures were most recently blamed for a series of electrical fires that eventually grounded Boeing's fleet of 787 Dreamliner aircraft in early 2013.

The researchers who developed the new battery have created a company -- Elegus Technologies -- to help market their innovation. They hope to begin mass production of the safer, rechargeable batteries in late 2016.

Lithium-ion batteries can sometimes experience problems when the barrier separating the electrodes allows lithium atoms to build up in a fernlike structure that eventually breaks through the membrane. That dendrite structure, as it is called, can then provide a new pathway for electrons and cause a battery to short-circuit.

A Battery Energy Boost

"The special feature of this material is we can make it very thin, so we can get more energy into the same battery cell size, or we can shrink the cell size," said Dan VanderLey, an engineer who co-founded Elegus and also serves as the startup's CIO and CMO. "We've seen a lot of interest from people looking to make thinner products."

In addition to being thin, the Kevlar-based material makes it possible to create lithium-ion battery membranes with super-small pore sizes of just 15 to 20 nanometers. (A nanometer is one-billionth of a meter.) That tiny pore size prevents lithium dendrites -- which are generally 20 to 50 nanometers across at the tip -- from being able to pass through the membrane.

Kevlar brings one more advantage as well: it doesn't conduct electricity.

"Unlike other ultra-strong materials such as carbon nanotubes, Kevlar is an insulator," said Nicholas Kotov, a professor of engineering at the University of Michigan. "This property is perfect for separators that...

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