Extra tough supercapacitor keeps charge after 40 hammer strikes

A new energy storage device can withstand a hammer striking it more than 40 times and is also nonflammable, unlike lithium-ion batteries, report researchers.

“Accidentally dropping electronics, such as a laptop or cellphone, is a common scenario that may lead to the failure of the device,” says Julio D’Arcy, assistant professor of chemistry at Washington University in St. Louis.

“In some cases, energy storage devices catch on fire due to impact-caused failure. The chance of impact damage will only increase as electronics become more flexible and worn on the human body.”

“This is the same mechanism that is responsible for the formation of rust on the surface of a wet piece of steel.”

By controlling the formation of rust in solution, researchers grew a micrometer-thick porous mat of conducting fibers affixed to a soft, pliable layer of organic plastic. The result is somewhat similar to an open-faced sandwich.

“This is the same mechanism that is responsible for the formation of rust on the surface of a wet piece of steel,” D’Arcy says.

“Here, we have carefully designed the nanostructure orientation so that a polymer film assembles parallel to a rusted surface. It produces an interwoven mat of polymer nanofibers with a textile-like structure that is flexible and ideal for storing energy in a supercapacitor.”

The researchers bent their new material to different angles over and over again. They hammered it repeatedly, and they also tested it against an impact equivalent to a car collision at 30 mph. The same amount of impact would fracture other materials such as metal and carbon.

The shatterproof supercapacitor held up well against these extreme tests: after the first hammer strike, it retained 80 percent of its ability to store energy at peak efficiencies; after 40 repeated strikes, it was still at 74 percent.

The new work appears in the journal Sustainable Energy and Fuels.

Source: Washington University in St. Louis