A material that can rapidly shut down an overheating lithium-ion battery and quickly restore the battery’s function as it cools is reported in a paper published online in Nature Energy this week. The highly thermoresponsive material may help to ensure the safe operation of rechargeable batteries.

Overheating is a common fire hazard caused by the overcharging of rechargeable batteries or internal electrical shorting.

Yi Cui, Zhenan Bao and colleagues developed a composite material that consists of graphene-coated spiky nickel nanoparticles mixed in a polyethylene plastic network. Upon heating, the plastic expands and separates the conductive nickel nanoparticles, which rapidly and substantially decreases the material’s conductivity (by 7-8 orders of magnitude in one second). After cooling, the plastic contracts and the material rapidly recovers its original conductivity. The authors used this highly thermoresponsive material to coat the current collectors in lithium-ion batteries and demonstrated that their approach achieves significantly higher sensitivity to temperature changes than previous switching devices.

The authors suggest that their method may improve future battery design and safety features. However, further research is required to determine whether the material can be applied to large-scale batteries, such as those used in electric vehicles.