Researchers at the University of Michigan are developing a new battery technology that uses Kevlar filament to thwart the growth of "metal tendrils" inside the cells, impeding the development of unwanted circuitry and preventing the power sources from erupting in flames.
The Kevlar-infused batteries could prevent battery fires like the one that created the electrical fire in the Boeing 787 Dreamliners in 2013. The research is so promising the team tapped the university's entrepreneurship program for support, according to Elegus Technologies, a company formed by the UM researchers who designed the batteries.
The research team choose the bullet-stopping Kevlar because the material can be formed extremely thin and can pack more punch per nanometer, according to Dan VanderLey, an engineer who helped fund Elegus through UM's Master of Entrepreneurship program. VanderLey says Elegus is getting great interest in the project.
The Elegus team chose Kevlar over carbon nanotubes and other ultrastrong materials because of its insulating properties, which makes it ideal to create separation inside the cells and to keep electrodes from shorting, according to Nicholas Kotov, a professor of engineering at UM.
The goal was to find a way to prevent the fern-like formation of dendrites from building up inside lithium-ion batteries, which can cause internal shorts.
When lithium-ion batteries pass electrons between electrodes, they are filtered through a membrane that funnels them through the batteries' circuitry. But when the lithium electrons build up into dendrites, the formation can poke through the membrane and create a short by touching both electrodes.
"The fern shape is particularly difficult to stop because of its nanoscale tip," says Siu On Tung, a graduate student in Kotov's lab, as well as chief technology officer at Elegus. "It was very important that the fibers formed smaller pores than the tip size."
So far, about 30 companies have been in touch with Elegus in search of samples of the Kevlar-fitted batteries. Elegus hopes to begin mass production of the bulletproof batteries at some point in 2016.
But right now, there is still more work Elegus would like to accomplish before mass producing the batteries. Elegus is satisfied with Kevlar's ability to insulate the circuitry inside of batteries, but the researchers would like to improve the speed at which the electrons flow -- improved flow will lead to faster recharge times because the cells can exchange their energies much more efficiently.
