New Stanford Battery Shuts Down at High Temperatures and Restarts When it Cools

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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.

"We can even tune the temperature higher or lower depending on how many particles we put in or what type of polymer materials we choose," said Bao, who is also a professor, by courtesy, of chemistry and of materials science and engineering. "For example, we might want the battery to shut down at 50 C or 100 C."

Reversible strategy

To test the stability of new material, the researchers repeatedly applied heat to the battery with a hot-air gun. Each time, the battery shut down when it got too hot and quickly resumed operating when the temperature cooled.

"Compared with previous approaches, our design provides a reliable, fast, reversible strategy that can achieve both high battery performance and improved safety," Cui said. "This strategy holds great promise for practical battery applications."

Other Stanford co-authors of the study are postdoctoral scholars Nan Liu, Chao Wang, Sean Andrews and Jia Liu; and graduate students Po-Chun Hsu, Jeffrey Lopez, Yuzhang Li and John To.

The research was supported by the SLAC National Accelerator Laboratory and the Precourt Institute for Energy at Stanford.

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