A wave of combustions caused by lithium-ion batteries built into hoverboards have made them go from the holiday’s hottest toys to potentially dangerous products, but a chemical engineering professor from Stanford University, Zheenan Bao, created a tool that could make these gadgets safer.

The device is what Fortune describes as “batteries with a built-in safety switch.” Bao’s creation is a polymer composed of nickel and graphene that shuts down overheating batteries in a fast time frame.

Lithium-ion batteries have a penchant for running hot. The lightweight element has the ability to store a lot of energy, but is known to be unstable, which is why fires have started in everything from Sony laptops to Boeing 787s when the compound is used as a power source.

One explanation Wired had as to why these hoverboards were blowing up was because their batteries were prone to significant defects. The ignitions would start whether the device was plugged in or just sitting stationary in its packaging.

Jay Whitacre, a professor of materials science & engineering at Carnegie Mellon, told the publication the market was being flooded with low-quality batteries because the boards were becoming a popular holiday product and the more-affordable items were using cheaper components to entice shoppers.

Bao’s thin polymer would be built into layers of the battery and would activate when the battery starts heating up, according to Fortune. The polymer would begin to expand to take energized particles away from each other to shut down the electric current.

As the battery begins to cool down, the polymer would condense so the battery can be used again, keeping its performance capabilities intact.

Bao’s research was published in the journal Nature Energy. She told Fortune that her hope is to license and be able to fund more research in this field.