Created battery that overheating does not explode, but simply stops working – BBC

Because of its high energy lithium-ion batteries have become very popular since the early 90-ies and then quickly pushed the more conventional nickel-metal hydride battery. Today, lithium-ion batteries are widely used in a variety of portable devices, including laptops, cell phones and MP3 players.

However, the high density of stored energy can provoke an internal short circuit, the subsequent fire power and even its explosion.

Manufacturers of gadgets with the problem of overheating occur constantly. For example, last year, the problem of overheating of lithium-ion batteries ran corporation Sony – it had to recall 9.6 million batteries that come with laptops Apple, Toshiba, Fujitsu, Sharp and Acer. Regularly in the media appear news on fire iPhone , for example, in March 2015 American got burned legs after the explosion of iPhone 5S in a pants pocket.

Of course , coined already a lot of ways to protect these batteries overheating and fire, but all of them, in addition to a substantial rise in price of batteries, suffer from one trudnoispolnimym drawback:

battery salvaged from overheating, it takes a lot time for recovery, if such a recovery at all possible.

The method proposed by the Stanford group is surprisingly simple and witty – details he presented on Monday in the journal Nature Energy . The method is the invention of one of the participating groups – Chzhenan Bao, who recently created a compact sensor for monitoring the temperature of the human body. The basis of the sensor were embedded in plastic with a nickel nanoparticles, “antennae” that protruded above the surface. Several modifying the sensor, they turned it into an efficient and trouble-free fuse. Satiate their “whiskered” particles of nickel film of graphene, the researchers then covered it with a thin plastic film. Finally, all of this “economy” wrapped one of the electrodes of the battery. At normal temperatures, the coating does not manifest itself as “antennae” nickel particles in contact with each other and a wonderful way to conduct current.

But when temperatures rise above a predetermined limit – polyethylene expanded and opens the “whiskers” and battery, respectively, stopped to give a current.

As soon as the temperature falls below the critical value, “antennae” again connected and the battery as if nothing had happened resumed the interrupted work .

Researchers “chasing” fuses in different modes. They forced the batteries to overheat or placed in a very hot environment. The result was always the same: when the battery temperature threshold is exceeded, disconnected, and when cooled immediately started working. The temperature was controlled off, scientists more or less of nickel nanoparticles, and, as stated in the article, thereby able to raise the temperature off the battery to 100 ° C.