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Wearable device battery could last 10 years

Agam Shah | April 25, 2014
Researchers have designed a battery that could keep wearable and health care devices running for 10 or more years without a recharge.

Researchers have designed a battery that could keep wearable and health care devices running for 10 or more years without a recharge.

The new design, based on the lithium carbon fluoride (CFx) chemical formula, could also lead to batteries that are safer than current ones. A prototype battery based on the formula was tested by researchers at the U.S. Department of Energy's Oak Ridge National Laboratory, and a related paper was published in the Journal of the American Chemical Society last week.

The CFx batteries could be as small as coins, and could last for years in low-power fitness trackers or wearable devices with sensors, said researcher Chengdu Liang, the lead author of the paper.

"The battery is not going to be recharged. It's one-time use," Liang said.

Wearable devices typically transmit small bursts of information and don't demand much energy, which can prolong life of the CFx battery. The battery could be desirable for sensors and human implants like pacemakers, which are difficult to recharge or replace, Liang said.

The prototype CFx battery in its current form is not intended for use in computers and mobile devices, which consume more energy than sensors and rely on recharges, Liang said.

"This study is proof-of-concept research, but we have been contacted by a private company interested in commercializing the battery. It could become a reality in a few years depending on the commercialization timeline," Liang said.

Today's batteries do not last very long and some are considered unsafe. PC makers Sony and Lenovo recently reported cases of lithium-ion batteries causing laptops to overheat and burn.

Research for new batteries using zinc-air and lithium-air technology is underway. Some alternative batteries such as those using silver-zinc are considered too expensive. The promise of fuel cells is catching on with car makers.

To be sure, the CFx chemical formula for batteries isn't new. Special batteries based on the formula are apparently sold by companies like Contour Energy for use by the military in drones, night-vision goggles and other electronics. Those batteries are available in different sizes. Contour Energy did not respond to calls, and emails bounced back.

But according to existing research from the U.S. Army, the CFx chemical formula is "known to have one of the highest theoretical energy capacities compared to other popular lithium cell chemistries."

"It is based on the old theory and with the new design," ORNL's Liang said. "This is a big breakthrough."

During an experiment, the ORNL researchers developed and tested an actual CFx battery, but used a solid electrolyte to add more energy capacity. Current lithium-ion batteries have electrodes in the form of a positive cathode and a negative anode, and electrolytes in between so charged lithium ions can move around. When charging a battery, lithium ions move from a cathode to an anode for storage. In discharge, the lithium ions move from the anode to the cathode, and out to the device.

 

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