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Researchers at Stanford have invented a battery that shuts down when it gets hot. This could prevent fire accidents involving many devices including phones.

According to CNET, the lithium-ion battery shuts down when the temperature crosses a predetermined temperature threshold. Researchers said the battery automatically powers on after cooling. The design relies on a new type of polymer developed by the researchers.

"People have tried different strategies to solve the problem of accidental fires in lithium-ion batteries," said Zhenan Bao, a chemical engineering professor, in a press release. "We've designed the first battery that can be shut down and revived over repeated heating and cooling cycles without compromising performance."

Bao and other researchers designed a polymer comprising spiky nickel particles coated with graphene. The polymer allows conduction of electricity but acts as a circuit breaker when temperature increases. As the battery operates, the temperature mounts. When the heat from the electrode separates the nickel particles in the polymer due to its expansion, the material stops conducting and halts the battery's operation.

"We can tune the temperature higher or lower depending on how many particles we put in or what type of polymer materials we choose. For example, we might want the battery to shut down at 50 C or 100 C," Bao said.

Researchers demonstrated the battery powering an LED when operating within prescribed temperature limits. Increasing its operational temperature prevented the LED from turning on.