New developed batteries will protect themselves from overheating shutting down when it’s necessary and restarting when they’re cool.
The revolutionary li-ion batteries have been developed by Stanford researchers to provide a plus of safeness to users of laptops, navigation systems and even hoverboards. Many of these products have been recalled after their batteries set on fire as a result of overheating, posing danger upon their users.
One of the developers, chemical engineering professor Zhenan Bao of Stanford university claims their research came from a necessity after people have tried for a long time to solve the overheating problems of li-ion batteries leading to accidental fires.
The new battery designed by Stanford researchers is the first battery which can be repeatedly shut off when overheated and turned back on when cool without compromising its performance.
The process of developing the battery is explained by Bao and her team in a study published in Nature Energy journal on January 11.
According to the team, a regular li-ion battery is made out of two electrodes and an electrolyte. The electrolyte can be a gel or a liquid which carries charged particles between the electrodes. Overcharging, shorting or puncturing the battery generates heat. If the heat reaches temperatures of over 300 degrees Fahrenheit/150 Celsius, the overheated electrolyte can catch fire making the battery explode.
Previous attempts to improve the batteries safeness were tricks such as inserting fire retardants into the electrolyte. However none of the previous techniques made the consequences of overheating reversible so the battery was damaged forever as a result.
Bao together with Yi Cui and Zheng Chen used nanotechnology to solve the problem. Some time ago Bao developed a wearable thermometer built of a plastic film embedded with nanoparticles of nickel extended with some nano-spikes. The same sano-spikes were coated with graphane, with a nano-layer of carbon and then embedded in an elastic polyethylene film to make the battery which protects itself from overheating.
The nano-spikes have to touch one another to conduct electricity so when the polyethylene stretches as a result of overheating it spreads the spikes apart of each other so the electricity won’t flow through the battery making it shut down. When the temperature drops below 160 degrees Fahrenheit the polyethylene film shrinks again so the nano-spikes get back in contact generating electricity which turns the battery back on.
Depending on the type of polymer chosen and the number of spikes added, researchers can make the battery shut down at other temperatures. So the technology is safe, reliable and reversible which makes the developers sure that the batteries that will protect themselves from overheating will play an important role in the future of technology.
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