New battery technology can take a beating, and then some

We all deal with batteries every day. The miniature power plants embedded in our devices are an indispensable and unavoidable fact of life, demanding to be charged and recharged around the clock, a never-ending feeding cycle with no letup.

Little wonder that discovering or developing the next big thing in battery technology has been keeping researchers and scientists burning the midnight oil. Lithium-ion (Li-ion) batteries, because of their energy and power performance, have become the industry standard for uses ranging from smartphones and iPads to aerospace and military apps.

Still, they're not the safest things in the world. The organic electrolytes used in Li-ion battery cells are highly flammable, toxic, moisture sensitive and thus limit and dictate the size and shape of packages they can come in.

So while a longer-and-longer-lasting charge is an obvious primary goal of cutting-edge research, what about making Li-ion batteries tougher, safer and more secure?

A team of researchers from Johns Hopkins University Applied Physics Laboratory, the University of Maryland (UMD) and the Army Research Lab has developed a new kind of lithium-ion battery that can "keep on going", like the Energizer Bunny, in the extremes of the battlefield.

In the demo, the shiny brass-colored prototype is about the size of an energy bar and wired up to a purring fan. The battery is then twisted, bent and folded while the fan continues without interruption.

It is then cut with a scissors from the bottom up and then submerged in synthetic seawater, and the fan doesn't miss a beat.

It is then pummeled repeatedly with the metal head of an air cannon projectile with no interruption in service.

The team's discovery was recently published in the journal Advanced Materials under the title Flexible Aqueous Li-ion Battery with High Energy and Power Densities.

Co-author Wang Chunsheng, professor of chemical and biomolecular engineering at UMD who got his PhD from Zhejiang University in 1995, said that the work builds on a novel "water-in-salt" electrolyte technology he developed two years ago.

"We are starting to transition this technology into novel battery architectures and demonstrate its practical potential," Wang said.

By embedding the water-in-salt electrolyte in a vinyl plastic matrix they created what they call a "gel polymer electrolyte, or GPE, virtually a battery blob.

"We are also expanding the list of available materials that can be used to make working cells with long cycle life," said Xu Kang, electrochemistry team leader and research fellow at the Army Research Lab.

Kostas Gerasopoulos, senior research scientist at Johns Hopkins, explained that what limits the size and shape of conventional Li-ion batteries is the flammable nature of organic electrolytes, requiring packaging and protective measures.

"When the water-in-salt electrolyte was introduced, I thought that making a stable polymer version would radically change the way Li-ion batteries are made and used," he said.

"By making the batteries flexible and lighter compared to the devices currently used, you can significantly decrease the large space and weight that the power source usually took," said Chongyin Yang, lead author of the paper.

The twisting, cutting, dunking and shooting demonstration - carried out without any safety glitches - made a dramatic point.

"We wanted to show the real implications of this technology in practical applications," Gerasopoulos said.

"Particularly for our military, with our warfighters exposed to extreme conditions and environments during their missions, the capability to maintain both safety and performance is unprecedented."

Withstanding the multi-tasking texting, posting, gaming and WeChatting of a hyped-up millennial will be the real acid test.

Contact the writer at chrisdavis@chinadailyusa.com.