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

Feb 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.

This video is not supported by your browser at this time.

"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: Engineers complete first comprehensive mesh-free numerical simulation of skeletal muscle tissue

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

Related Stories

Researchers make new electronics -- with a twist

Nov 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'

Jul 02, 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

Desktop device to make key gun part goes on sale in US

10 hours ago

The creator of the world's first 3D plastic handgun unveiled Wednesday his latest invention: a pre-programmed milling machine that enables anyone to easily make the core component of a semi-automatic rifle.

Minimally invasive surgery with hydraulic assistance

16 hours ago

Endoscopic surgery requires great manual dexterity on the part of the operating surgeon. Future endoscopic instruments equipped with a hydraulic control system will provide added support during minimally ...

Analyzing gold and steel – rapidly and precisely

18 hours ago

Optical emission spectrometers are widely used in the steel industry but the instruments currently employed are relatively large and bulky. A novel sensor makes it possible to significantly reduce their size ...

More efficient transformer materials

18 hours ago

Almost every electronic device contains a transformer. An important material used in their construction is electrical steel. Researchers have found a way to improve the performance of electrical steel and ...

Sensor network tracks down illegal bomb-making

18 hours ago

Terrorists can manufacture bombs with relative ease, few aids and easily accessible materials such as synthetic fertilizer. Not always do security forces succeed in preventing the attacks and tracking down ...

Miniature camera may reduce accidents

19 hours ago

Measuring only a few cubic millimeters, a new type of camera module might soon be integrated into future driver assistance systems to help car drivers facing critical situations. The little gadget can be ...

User comments : 2

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