Researchers at Stanford University have developed a system for smartphones that lets the owners know when their phones are overheating and about to catch fire.
Yi Cui, associate professor of materials science and engineering at the university, said the point of the system is keep smartphone owners, as well as their devices, safe from their batteries overheating, according to CNET.
Lithium-ion batteries can destroy devices when they overheat, and while these cases rarely occur, they still pose a huge problem. In addition to smartphones, this issue affects laptops, e-readers, cars, planes and other machines powered by a lithium ion battery. Boeing grounded a 787 fleet in 2013 after the lithium-ion batteries on the plane caught fire.
"The system can detect problems that occur during the normal operation of a battery, but it does not apply to batteries damaged in a collision or other accident," Cui said.
These batteries come with a lithium oxide cathode and a graphite anode, which are separated by a thin, porous polymer sheet designed to let ions move between the two electrodes, Science Now reported. Overheating and catching fire can occur when a lithium-ion cell overcharges, leading to tiny chains of lithium called "dendrites" coming out of the anode and piercing through the polymer separator and touching the cathode. This can lead to an electrical current moving through the dendrites to the cathode to short-circuit the cell.
The research team's "smart" separator consists of a 50-nanometer thin layer of copper placed between two polymer sheets. The copper layer is connected to a third electrode in order to measure voltage. The voltage between the anode and the copper layer goes down to zero when the dendrites get to the separator. This alerts smartphone users that they should change their battery while it is still working safely, which gives them a chance to avoid the battery exploding.
Cui said the issue with lithium-ion cells exploding becomes more serious with bigger batteries, CNET reported.
"Some electric cars today are equipped with thousands of lithium-ion battery cells. If one battery explodes, the whole pack can potentially explode," Cui said.
Hui Wu, co-lead author and postdoctoral fellow in the team, said the conducting layer doesn't help the battery perform better, but it can make the battery a lot safer to use.
"And it can be used in any battery that could require you to detect a short before it explodes- a very useful feature as more and more large machines - particularly vehicles - make use of lithium ion batteries," Wu said.
The team's research was published in the journal Nature Communications and can be viewed online.
