New material aims to make lithium-ion batteries safer

A new material developed by Taiwanese researchers aims to put an end to fires and explosions caused by the lithium-ion batteries commonly found in phones and other mobile devices.

Lithium-ion technology is used in batteries for most electronic devices today, from iPods and the iPhones to laptops, digital cameras and more. The technology has been considered safe for years, but damage and production defects have led to high profile fires and small explosions. A few years ago, several laptop battery fires prompted Sony to spend hundreds of millions of dollars on a massive lithium-ion battery recall.

This same battery technology is now being used in hybrid vehicles and electric cars.

To make lithium-ion batteries safer, Taiwan's publicly funded Industrial Technology Research Institute (ITRI) developed a new polymer, STOBA (self-terminated oligomers with hyper-branched architecture) to keep them from overheating. The polymer is added to the cathode material inside a lithium-ion battery.

"Fires or explosions in these batteries are caused by short circuits," said Wu Hung-chun, a researcher at ITRI, explaining that even minor mishandling such as dropping the handset could result in damage causing a short circuit.

The answer was to develop STOBA, which suppresses thermal heat in case of a puncture or other severe damage. Wu showed a video of tests of a common nail puncturing a mobile phone battery, which caused it to heat up to over 650 degrees and explode. A second test on a mobile phone battery with STOBA technology saw the heat reach only 140 degrees. The researcher warned that people should not try such experiments at home.

ITRI is currently working on a production process for STOBA, Wu said, adding that the technology will only add about 2 or 3 percent to the overall cost of a lithium-ion battery.

"The technology is ready for lithium-ion batteries used in electronic devices, mobile phones, laptops, no problem," he said. ITRI has already started testing STOBA on electric car batteries.

The Taiwanese research group isn't the first to develop safety technology for lithium-ion batteries. Sony, Toshiba and other lithium-ion battery makers have been working to improve the batteries for years. Three years ago, Panasonic announced a heat-resistive insulating layer inside its battery cells meant to keep the batteries from overheating in the event of a short circuit.

ITRI also on Thursday announced an agreement to work with E-One Moli Energy to explore ways to make lithium-ion batteries for hybrid cars and electric cars safer and more efficient.

The five-year deal was made in part to take advantage of government incentives to promote alternative energy projects and to take advantage of new technology for lithium-ion batteries.

E-One makes batteries for BMW's Mini E, an experimental electric car that uses lithium-ion batteries.

E-One's latest electric car battery prototype, the eTaxi BEV, costs US$100,000 currently, gives a car a range of 120-150 miles (190-240-kilometers) before needing a recharge, charges in two to five hours and accelerates from 0 to 60 miles per hour in 7 seconds. The battery contains 5,000 cells, compared to the 3 to 8 cells found in common laptop batteries.

IDG News Service

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