Summary:

A Rice University team developed a film that shares characteristics with both batteries and ultracapacitors, and is now in talks with companies interested in commercializing it.

A thin-film energy storage device retains its battery- and supercapacitor-like qualities even after being flexed 1,000 times. Photo courtesy of Jeff Fitlow/Rice University.
photo: Jeff Fitlow/Rice University

The coming wave of wearable devices will demand a sleeker and more powerful battery than the one you’ll find in the Timex on your wrist. With an eye toward electronics that could fit snugly around your wrist while remaining super thin, a laboratory at Rice University set out to develop a material that is both flexible and capable of storing as much energy as a traditional battery.

The resulting material, which the team described today in the Journal of the American Chemical Society, is as thick as two sheets of paper and able to withstand repeated bending. It can be stacked or made larger to provide more power. The team believes it could be made even thinner in the future.

A thin-film energy storage device retains its battery- and supercapacitor-like qualities even after being flexed 1,000 times. Photo courtesy of Jeff Fitlow/Rice University.

A thin-film energy storage device retains its battery- and supercapacitor-like qualities even after being flexed 1,000 times. Photo courtesy of Jeff Fitlow/Rice University.

Most high-performance batteries in use today contain lithium, which lends them a large capacity for storing energy. But high capacity materials are also generally brittle, which makes them difficult to incorporate into flexible devices. The team opted to use nickel instead of lithium, and gave the film a structure similar to an ultracapacitor instead of a battery.

“It behaves like a battery but the structure is that of a supercapacitor. If we use it as a supercapacitor, we can charge quickly at a high current rate and discharge it in a very short time,” paper co-lead author Yang Yang said in a release. “But for other applications, we find we can set it up to charge more slowly and to discharge slowly like a battery.”

Team lead James tour said his lab is now in talks with companies interested in commercializing the technology. There are already thin, mildly flexible batteries on the market, but they do not flex as far or provide the unusual battery/ultracapacitor combination on which the Rice team is working. Other labs are currently working on making super thin batteries out of emerging materials like carbon nanotubes, which are also highly flexible.

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