Researchers from Stanford University have invented a new lithium-ion battery regulated by its temperature - here's how it works.
A team of Stanford researchers has just made a stunning breakthrough in battery technology. According to a report from UPI, a new design for a lithium-ion battery with the ability to self-regulate its temperature could soon find its way into your favorite consumer electronics like laptops and hoverboards.
Researchers believe that the battery, which has the ability to turn itself off when it becomes too hot, can help prevent battery fires and improve the safety of a wide range of electronic devices. According to Zhenan Bao, a chemical engineering professor from Stanford, “People have tried different strategies to solve the problem of accidental fires in lithium-ion batteries. We’ve designed the first battery that can be shut down and revived over repeated heating and cooling cycles without compromising performance.”
A typical lithium-ion battery consists of two lithium electrodes with a positive and a negative charge, and an electrolyte liquid or gel in the center that allows ions to move back and forth between the two electrodes, sharing their electrons along the way.
The cycle of exchanging electrons between positive and negative ends of a battery can lead to dangerous spikes in temperatures in the intermediary electrolyte material. A temperature spike above 300 degrees Fahrenheit can result in a potentially deadly explosion.
One of the most notable cases of this happening was seen in the increasingly popular hoverboard, a device that allows people to roll around on the ground without taking a single step. News stories began to surface of the devices exploding while they were charging, and some universities have even banned the vehicles from their campuses.
Stanford researchers placed a thin film of elastic polyethylene between the charged electrodes and the intermediary material. The film, containing sharp nickel nanoparticles coated with graphene, enhances conductivity inside the battery.
“We attached the polyethylene film to one of the battery electrodes so that an electric current could flow through it,” says lead author Zheng Chen. “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.”
The film stretches out to the point where it no longer conducts electricity as it reaches a certain threshold, allowing heat to dissipate before the nanoparticles can touch and begin conducting electricity again. The prototype design began to shut down when the electrolyte material reached a temperature of 160 degrees Fahrenheit.
A Stanford press release describing the new technology can be found here.