Newly invented adaptable lithium ion batteries stop if overheated, and restart soon after they’ve cooled, thus being much safer than their older versions, which can become highly flammable at times.
The gadgets were developed by a team of experts at Stanford University, led by Zhenan Bao, professor of chemical energy, and the achievement was detailed in a study featured in the journal Nature Energy, on Monday, January 11.
On an annual basis, several hundreds of millions lithium ion batteries are manufactured worldwide, being commonly incorporated in countless portable devices, which require recharging, such as laptops, cellphones, PDAs, cameras etc.
Usually, such batteries are appreciated for their ability to store large amounts of energy, despite their relatively small size and compact shape.
While they don’t generally represent a safety hazard, in some cases after being used or charged for excessive lengths of time, they can overheat, eventually melting, being engulfed in flames or exploding after suffering a short circuit.
Such incidents have actually become a relatively frequent occurrence this holiday season, when several hoverboards powered by lithium ion batteries malfunctioned, setting on fire entire homes across the United States.
What was initially believed to be the most sought-after Christmas toy, was soon viewed as a perilous gadget, best avoided by customers.
Several retailers decided to remove the self-balancing electric scooters off their shelves, and ceased to commercialize the faulty products, while major airlines banned the vehicles from being taken on board, so as not to disrupt the flight or put the safety of passengers and crew at risk.
Such heavily publicized incidents served as incentives for researchers to work on a much more secure lithium battery, that can power devices without malfunctioning while overheated.
For instance, experts at the Massachusetts Institute of Technology proposed countering problems by relying on solid-state electrolytes, instead of liquid ones, while others suggested combining the substances with flame retardants.
Yi Cui, associate professor of materials science and engineering at Stanford University, was successful in developing a lithium ion battery that can issue a signal when it gets too hot, and afterwards promptly shuts down.
Now, Stanford researchers have made even more progress in this field, by creating such a smart battery that not just stops working while overheated, but also promptly reactivates as its temperature drops to the point where the device is once again deemed to be safe. The batteries were inspired by the lead developer’s previously invented wearables, which can monitor the body’s temperature.
They are made up of nickel nanoparticles, exhibiting multiple spiky protuberances. Those tiny fragments are wrapped in polyethylene (the most common type of plastic) and afterwards covered in graphene.
So as to successfully allow electricity pass through them, the nanoparticles must brush against each other, but when temperatures increase, getting close to 160 degrees Fahrenheit, the plastic expands.
Since the nickel pieces are no longer adjoining, the battery stops working, but as it cools, the polyethylene contracts, allowing the particles to touch once again, and to conduct electricity as before.
It’s for the first time that scientists have proved so convincingly that lithium-ion batteries can be enhanced in order to eliminate all fire hazards associated with them.
George Crabtree, director at the Joint Center for Energy Storage Research (a structure within the Argonne National Laboratory), has welcomed the discovery, considering it a real breakthrough, especially for the electric vehicle industry.
As Crabtree explains however, further testing should be conducted so as to determine if the new lithium ion batteries can stay safe even after stopping and restarting several times, or if this process becomes progressively less effective and reliable.
Image Source: Stanford
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