New lithium-ion battery shuts down before overheating and restarts as soon as it cools.
Researchers from Stanford University have developed a new battery that won’t overheat and make devices catch fire. The battery shuts itself down as the temperature gets too high and restarts immediately once it cools.
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The new lithium ion battery is designed after the rash of incidents involving battery-powered devices like laptops, hoverboards and navigation systems. Numerous incidents of fire caused by rechargeable batteries have prompted recalls and bans on a wide range of batteries.
"People have tried different strategies to solve the problem of accidental fires in lithium-ion batteries,” said Zhenan Bao, a professor of chemical engineering at Stanford University. "We've designed the first battery that can be shut down and revived over repeated heating and cooling cycles without compromising performance."
Regular lithium ion batteries are made up of two electrodes and electrolyte liquid or gel that transfers electrons from one end to another. But these traditional batteries have a big problem in them. Under certain circumstances like short circuit or overcharging, batteries can generate heat and catch fire and even trigger explosions if temperature exceeds around 300 degrees Fahrenheit. This shortcoming makes these batteries unsafe for consumers.
To address the longstanding problem, Stanford scientists used nanotechnology. They connected a thin film of elastic polyethylene with electrode. The film contains tiny particles of nickel with nanoscale spikes and then the particles were coated with graphene.
"We attached the polyethylene film to one of the battery electrodes so that an electric current could flow through it," said Zheng Chen, lead author of the study. "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."
When battery heats up above 160 degrees Fahrenheit, the polyethylene film expands like a balloon, separates spiky particles and cause battery to shut down but when it drops down to 160 F, the film shrinks , assembles all the scattered particles and restarts the battery.
The latest technique is reversible and does opposite of conventional techniques. Batteries with current techniques cannot function after they overheat. Moreover, new battery ensures safety as well.
“Compared with previous approaches, our design provides a reliable, fast, reversible strategy that can achieve both high battery performance and improved safety,” said Yi Cui, co-author of the study.
“This strategy holds great promise for practical battery applications.”