Researchers at Stanford have designed the first lithium-ion battery that can shut down and restart on its own to prevent overheating.
“The battery shuts [itself] down before overheating, then restarts immediately when the temperature cools,” reported Stanford News.
The authors of the study used graphene-and-carbon-coated nanoscale spiky nickel particles embedded in a thin film of elastic polyethylene for the battery experiment.
“We attached the polyethylene film to one of the battery electrodes so that an electric current could flow through it,” explained the lead author of the study, Zheng 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.”
Stanford News reported that, “When the researchers heated the battery above 160 F (70 C), the polyethylene film quickly expanded like a balloon, causing the spiky particles to separate and the battery to shut down. But when the temperature dropped back down to 160 F (70 C), the polyethylene shrunk, the particles came back into contact, and the battery started generating electricity again.”
Zhenan Bao, a co-author and professor at Stanford, said that the temperature can even be tuned higher or lower “depending on how many particles we put in or what type of polymer materials we choose.”
Heat from a hot-air gun was repeatedly applied to the battery to test the stability of new material, and Stanford News confirmed that “each time, the battery shut down when it got too hot and quickly resumed operating when the temperature cooled.”
Bao also commented that “the heating and cooling cycles can be done repeatedly without compromising performance.”
“Compared with previous approaches, our design provides a reliable, fast, reversible strategy that can achieve both high battery performance and improved safety,” Yi Cui said, co-author and Stanford engineer who created a “smart” battery in 2014 that provided a warning before overheating, which this new lithium-ion battery is inspired from, “This strategy holds great promise for practical battery applications.”
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