The most recent research to address these problems comes out of Stanford University. Researchers have developed a temperature sensor that can shut down the battery before it overheats, preventing a thermal runaway. In addition, the sensor is capable of restarting the battery automatically once it cools down.
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“We attached the polyethylene film to one of the battery electrodes so that an electric current could flow through it,” says Zheng Chen, lead author of the paper. “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.”