Researchers at Stanford University have developed a revolutionary graphene-enhanced polyethylene film that prevents a lithium-ion battery from overheating, then restarts the battery when it cools. This new technology could prevent fires and melt-downs in a wide range of battery-powered devices.
The researchers in this study recently invented a wearable sensor to monitor human body temperature, made of a plastic material embedded with tiny particles of nickel with nanoscale spikes protruding from their surface. For the battery experiment, they coated the spiky nickel particles with graphene and embedded the particles in a thin film of elastic polyethylene. They then attached the film to one of the battery electrodes so that an electric current could flow through it. The researchers explain that in order 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 non-conductive so that electricity can no longer flow through the battery.