Lithium-ion batteries are the backbone of many electronic devices providing power to tablets, laptops and cameras. Unfortunately, these batteries come with risks. They can overheat and cause explosions and fires.

Potentially deadly accidents caused by overheating batteries though such as in the case of the exploding hoverboards may no longer be a problem in the future. Scientists from Stanford University have designed a lithium-ion battery that won't overheat and catch fire.

The battery can shut itself when the temperature gets too high and then powers itself on after it has cooled enough. Zheng Chen, from Stanford University, and colleagues, who developed the battery, said that the new technology can help prevent fires in electronics caused by overheated power supply.

How The New Battery Works

The cycle of charging and discharging in an average lithium-ion battery can sometimes push the temperature of the battery's electrolyte material to extreme. The battery then catches fire and causes explosion of flames.

Chen and colleagues came up with a work around for this problem by surrounding the battery with a thin elastic film of polyethylene. The film has conductive spiky nanoparticles composed of nickel and is coated with graphene to boost conductivity.

The rechargeable lithium-ion battery currently used has two lithium electrodes and an electrolyte that allows for the transfer of electrons.

In the case of the new battery, the conductive metal particles move away from each other when the battery heats up and expands, shutting it down. The film contracts as the battery cools and the nickel particles start to touch again turning back on the battery's power.

"We attached the polyethylene film to one of the battery electrodes so that an electric current could flow through it," said Chen. "To conduct electricity, the spiky particles have to physically touch one another. But during thermal expansion, polyethylene stretches. That causes the particles to spread apart, making the film nonconductive so that electricity can no longer flow through the battery."

The prototype battery shuts down once the temperature rises to above 160 degrees Fahrenheit or 71 degrees Celsius, but the researchers said it is possible to tune the temperate to higher or lower. This can be done by adjusting the amount of particles they use. It may also depend on the type o polymer materials used.

The researchers experimented with the new material by connecting it to a LED light and then blasted it with hot air gun. Once the heat was applied, the light switched off and turned back on after the heat source was removed.

Once this technology is applied, people may no longer have to worry about overheating batteries that can cause dangerous accidents.

"We believe that these conversion-reaction-based cathode additives will have important applications in existing Li-ion batteries, as well as future advanced battery systems involving high-capacity anodes (for example, Si and Sn) with large first-cycle capacity loss," the researchers wrote in their study published in the journal Nature on Jan. 11.

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