Stretchable lithium-ion battery can twist, bend, return to normal shape (w/ Video)

February 26, 2013 by Megan Fellman
Credit: Northwestern University

(Phys.org)—Northwestern University's Yonggang Huang and the University of Illinois' John A. Rogers are the first to demonstrate a stretchable lithium-ion battery—a flexible device capable of powering their innovative stretchable electronics.

No longer needing to be connected by a cord to an , the stretchable now could be used anywhere, including inside the human body. The implantable electronics could monitor anything from to , succeeding where flat, rigid batteries would fail.

Huang and Rogers have demonstrated a that continues to work—powering a commercial light-emitting diode (LED)—even when stretched, folded, twisted and mounted on a human elbow. The battery can work for eight to nine hours before it needs recharging, which can be done wirelessly.

The new battery enables true integration of electronics and power into a small, stretchable package. Details will be published Feb. 26 by the online journal Nature Communications.

The video will load shortly

"We start with a lot of battery components side by side in a very small space, and we connect them with tightly packed, long wavy lines," said Huang, a corresponding author of the paper. "These wires provide the flexibility. When we stretch the battery, the wavy interconnecting lines unfurl, much like yarn unspooling. And we can stretch the device a great deal and still have a working battery."

Huang led the portion of the research focused on theory, design and modeling. He is the Joseph Cummings Professor of Civil and Environmental Engineering and at Northwestern's McCormick School of Engineering and .

The power and voltage of the stretchable battery are similar to a conventional of the same size, but the flexible battery can stretch up to 300 percent of its original size and still function.

Rogers, also a corresponding author of the paper, led the group that worked on the experimental and fabrication work of the stretchable battery. He is the Swanlund Chair at the University of Illinois at Urbana-Champaign.

Huang and Rogers have been working together for the last six years on stretchable electronics, and designing a cordless power supply has been a major challenge. Now they have solved the problem with their clever "space filling technique," which delivers a small, high-powered battery.

For their stretchable electronic circuits, the two developed "pop-up" technology that allows circuits to bend, stretch and twist. They created an array of tiny circuit elements connected by metal wire "pop-up bridges." When the array is stretched, the wires—not the rigid circuits—pop up.

This approach works for circuits but not for a stretchable battery. A lot of space is needed in between components for the "pop-up" interconnect to work. Circuits can be spaced out enough in an array, but battery components must be packed tightly to produce a powerful but small battery. There is not enough space between battery components for the "pop-up" technology to work.

Huang's design solution is to use metal wire interconnects that are long, wavy lines, filling the small space between battery components. (The power travels through the interconnects.)

The unique mechanism is a "spring within a spring": The line connecting the components is a large "S" shape and within that "S" are many smaller "S's." When the battery is stretched, the large "S" first stretches out and disappears, leaving a line of small squiggles. The stretching continues, with the small squiggles disappearing as the interconnect between electrodes becomes taut.

"We call this ordered unraveling," Huang said. "And this is how we can produce a battery that stretches up to 300 percent of its original size."

The stretching process is reversible, and the battery can be recharged wirelessly. The battery's design allows for the integration of stretchable, inductive coils to enable charging through an external source but without the need for a physical connection.

Huang, Rogers and their teams found the battery capable of 20 cycles of recharging with little loss in capacity. The system they report in the paper consists of a square array of 100 electrode disks, electrically connected in parallel.

Explore further: Researchers make new electronics -- with a twist

More information: "Stretchable batteries with self-similar serpentine interconnects and integrated wireless recharging systems," Nature Communications, 2013. www.nature.com/ncomms/journal/v4/n2/full/ncomms2553.html

Related Stories

Researchers make new electronics -- with a twist

November 19, 2008

They've made electronics that can bend. They've made electronics that can stretch. And now, they've reached the ultimate goal -- electronics that can be subjected to any complex deformation, including twisting.

Researchers create 'rubber-band electronics'

July 2, 2012

For people with heart conditions and other ailments that require monitoring, life can be complicated by constant hospital visits and time-consuming tests. But what if much of the testing done at hospitals could be conducted ...

Recommended for you

Inferring urban travel patterns from cellphone data

August 29, 2016

In making decisions about infrastructure development and resource allocation, city planners rely on models of how people move through their cities, on foot, in cars, and on public transportation. Those models are largely ...

How machine learning can help with voice disorders

August 29, 2016

There's no human instinct more basic than speech, and yet, for many people, talking can be taxing. 1 in 14 working-age Americans suffer from voice disorders that are often associated with abnormal vocal behaviors - some of ...

Apple issues update after cyber weapon captured

August 26, 2016

Apple iPhone owners on Friday were urged to install a quickly released security update after a sophisticated attack on an Emirati dissident exposed vulnerabilities targeted by cyber arms dealers.

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Grallen
not rated yet Feb 26, 2013
I wonder... why the gloves? Contamination(or getting the prototype dirty), dangerous chemicals to touch, or they simply would get a little shock?
Smerff
not rated yet Feb 26, 2013
I imagine it's certainly A and C with the possibility of B given that it is probably in a laboratory environment and probably not given any real protection for commercial uses

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.