Sensor can warn of battery failure

Jan. 10, 2012 at 8:56 PM
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LAUREL, Md., Jan. 10 (UPI) -- Researchers in Maryland say they've built an inexpensive sensor that can warn of impending catastrophic failure in lithium-ion batteries.

The batteries power millions of consumer electronic devices and are the most common type of battery used in hybrid and electric vehicles, but safety concerns have been raised by reports of battery malfunctions and fires in vehicles, mobile phones and laptop computers.

Scientists at the Johns Hopkins University Applied Physics Laboratory say their sensor is based on a discovery of an intrinsic relationship between the internal temperature of lithium-ion cells and an easily measured electrical parameter of the cell.

Failures in lithium-ion batteries are typically caused by thermal runaway, a self-perpetuating condition that can occur once a cell reaches a critical temperature.

"An abnormally high internal cell temperature is a nearly universal manifestation of something going awry with the cell," researcher Rengaswamy Srinivasan said in a Johns Hopkins release Tuesday.

"These changes can occur within seconds, leading to a potentially catastrophic event if corrective measures are not taken immediately," he said. "When things start to go wrong inside the cell, time is not on your side.

"We discovered that we can measure the temperature of the protective layers between the electrodes and the electrolyte of the battery during normal operation," Srinivasan said. "These layers are where the conditions that lead to thermal runaway and catastrophic cell failure begin."

The sensor requires a simple electrical connection at the positive and negative terminals of the cell and can operate using power from the battery it is monitoring, researches said.

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