Global Sources
EE Times-Asia
Stay in touch with EE Times Asia
EE Times-Asia > Power/Alternative Energy
Power/Alternative Energy??

Early-warning system cuts fire risk for Li-ion batteries

Posted: 16 Oct 2014 ?? ?Print Version ?Bookmark and Share

Keywords:Stanford University? lithium-ion battery? electrode? copper?

A team of scientists at Stanford University has created a "smart" lithium-ion battery that will give sufficient warning before it overheats and burns. According to one of the researchers, the system can "detect problems that occur during the normal operation of a battery, but it does not apply to batteries damaged in a collision or other accident."

"Our goal is to create an early-warning system that saves lives and property," said Yi Cui, associate professor of materials science and engineering at Stanford University.

A series of well-publicised incidents in recent years has raised concern over the safety of lithium-ion batteries. In 2013, the Boeing aircraft company temporarily grounded its 787 Dreamliner fleet after the battery packs in two airplanes caught fire.

Copper coating on the polymer separator

In 2006, Sony recalled millions of lithium-ion batteries after reports of more than a dozen consumer-laptop fires. The company said that during the manufacturing process, tiny metal impurities had gotten inside the batteries, causing them to short-circuit.

"The likelihood of a bad thing like that happening is maybe one in a million," Cui said. "That's still a big problem, considering that hundreds of millions of computers and cellphones are sold each year. We want to lower the odds of a battery fire to one in a billion or even to zero."

A typical lithium-ion battery consists of two tightly packed electrodes a carbon anode and a lithium metal-oxide cathode with an ultrathin polymer separator in between. The separator keeps the electrodes apart. If it is damaged, the battery could short-circuit and ignite the flammable electrolyte solution that shuttles lithium ions back and forth.

"The separator is made of the same material used in plastic bottles," said graduate student Denys Zhuo, co-lead author of the study. "It's porous so that lithium ions can flow between the electrodes as the battery charges and discharges." Manufacturing defects, such as particles of metal and dust, can pierce the separator and trigger shorting, as Sony discovered in 2006. Shorting can also occur if the battery is charged too fast or when the temperature is too low a phenomenon known as overcharge.

"Overcharging causes lithium ions to get stuck on the anode and pile up, forming chains of lithium metal called dendrites," Cui explained. "The dendrites can penetrate the porous separator and eventually make contact with the cathode, causing the battery to short."

"In the last couple of years we've been thinking about building a smart separator that can detect shorting before the dendrites reach the cathode," said Cui, a member of the photon science faculty at SLAC National Accelerator Laboratory at Stanford.

1???2?Next Page?Last Page

Article Comments - Early-warning system cuts fire risk ...
*? You can enter [0] more charecters.
*Verify code:


Visit Asia Webinars to learn about the latest in technology and get practical design tips.

Back to Top