A
California startup is developing flexible, rechargeable batteries that
can be printed cheaply on commonly used industrial screen printers.
Imprint Energy, of Alameda, California, has been testing its ultra-thin
zinc-polymer batteries in wrist-worn devices and hopes to sell them to
manufacturers of wearable electronics, medical devices, smart labels and
environmental sensors.
The
company’s approach is meant to make the batteries safe for on-body
applications, while their small size and flexibility will allow for
product designs that would have been impossible with bulkier
lithium-based batteries. Even in small formats, the batteries can
deliver enough current for low-power wireless communications sensors,
distinguishing them from other types of thin batteries.
The
company recently secured $6 million in funding from Phoenix Venture
Partners, as well as AME Cloud Ventures, the venture fund of Yahoo
cofounder Jerry Yang, to further develop its proprietary chemistry and
finance the batteries’ commercial launch. Previous investors have
included CIA-backed venture firm In-Q-Tel and Dow Chemical.
The
batteries are based on research that company cofounder Christine Ho
began as a graduate student at the University of California, Berkeley,
where she collaborated with a researcher in Japan to produce microscopic
zinc batteries using a 3-D printer.
The
batteries that power most laptops and smartphones contain lithium,
which is highly reactive and has to be protected in ways that add size
and bulk. While zinc is more stable, the water-based electrolytes in
conventional zinc batteries cause zinc to form dendrites, branch-like
structures that can grow from one electrode to the other, shorting the
battery. Ho developed a solid polymer electrolyte that avoids this
problem, and also provides greater stability, and greater capacity for
recharging.
Brooks
Kincaid, the company’s cofounder and president, says the batteries
combine the best features of thin-film lithium batteries and printed
batteries. Such thin-film batteries tend to be rechargeable, but they
contain the reactive element, have limited capacity and are expensive to
manufacture. Printed batteries are nonrechargeable, but they are cheap
to make, typically use zinc and offer higher capacity.
Working
with zinc has afforded the company manufacturing advantages. Because of
zinc’s environmental stability, the company did not need the protective
equipment required to make oxygen-sensitive lithium batteries.
“When
we talk about the things that constrain us in terms of the development
of new products, there’s really two that I lose the most sleep over
these days. One is batteries and one is displays,” says Steven Holmes,
vice president of the New Devices Group and general manager of the Smart
Device Innovation team at Intel.
Despite
demand for flexible batteries, Ho says no standard has been developed
for measuring their flexibility, frustrating customers who want to
compare chemistries. So the company built its own test rig and began
benchmarking its batteries against commercial batteries that claimed to
be flexible. Existing batteries failed catastrophically after fewer than
1,000 bending cycles, she says, while Imprint’s batteries remained
stable.
Imprint
has also been in talks about the use of its batteries in clothes and
“weird parts of your body like your eye,” Ho says. The company also
recently began working on a project funded by the U.S. military to make
batteries for sensors that would monitor the health status of soldiers.
Other potential applications include powering smart labels with sensors
for tracking food and packages.
Posted by : Gizmeon
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