Research, Technology

Stretchy electronics grow even further with flexible batteries

The team tested their battery by stretching it 300% while it powered an LED lamp.

In just a couple of years, electronics will cross a new frontier of practicability and aesthetics as consumer goods will transition to flexible electronics. We’ve told you all about fantastic electronics that can stretch multiple times their own size all while housing delicate circuitry, hinting to prospects where they could be easily embedded into clothing or highly dynamic environments. Recently researchers at Northwestern University and University of Illinois have revealed their own contribution to flexible electronics, after they made a flat battery capable of stretching up to three times its own size.

One of the reason flexible electronics haven’t kicked off yet is the lack of reliable power sources that are equally flexible – this might change soon enough.

“Batteries are particularly challenging because, unlike electronics, it’s difficult to scale down their dimensions without significantly reducing performance,” said senior author of the study John Rogers of the University of Illinois at Urbana-Champaign.

Prof Rogers and colleagues have been working for years to develop a stretchy battery, and they finally reached tangible results after they settled with a “pop-up” architecture – tiny, widely spaced tiny circuit elements embedded within a stretchy polymer and connected with wires that “popped up” as the polymer was stretched.

Rather remarkably, the power and voltage capable of being stored and delivered by the stretchy battery is right on par with conventional lithium-ion batteries of the same size, being capable of working for up to nine hours without recharging. The latter is made wirelessly.

“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,” says Northwestern University’s Yonggang Huang.

“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.”

It will be some time before the battery hits the market or even becomes embedded in applications that much need them, like devices integrated with the outside of the body, on the skin, for health, wellness and performance monitoring, among other. The stretchy battery is still a prototype, and the one tested by the scientists only lasted for 20 charge/discharge cycles.

Findings were detailed in the journal Nature Communications.

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