This new non-exploding battery technology relies upon a flexible plastic sensor inside. The sensor has graphene-coated nickel nanoparticles embedded on it, each one covered in tiny spikes. During normal operation, the spikes are in contact with neighboring particles, which completes a circuit between the electrodes. As the temperature rises, the plastic sensor expands and pulls the nanoparticles apart. When the spikes are no longer in contact with one another, the circuit is broken and the battery stops working.
It might be a little concerning that your battery would just stop. This doesn’t kill the battery permanently, though. It’s a failsafe that should only kick in when the alternative is thermal runaway and a potential battery fire. As the temperature of the battery comes down, the nanoparticles move closer together and again form a circuit. The battery starts working again and you can go about your business. the temperature at which this happens can be adjusted by changing the number of particles embedded in the sensor.
The team tested the sensor in the lab with a simple hot air gun. When heated, the sensor breaks a circuit. Let it cool off, and it starts working again. Since the sensor is very thin and flexible, it should be easy to integrate it into existing battery technology. That very well may happen in the near future.