A new type of “smart” lithium-ion battery that can actually provide warning should there be a risk of overheating (and thusly fire hazard) has been developed by researchers from Stanford University.
The technology that enables the new abilities can be relatively easily incorporated into the sorts of lithium-ion batteries that are currently in common use — in everything from cellphones, to tablets, to laptops, to EVs, etc.
“Our goal is to create an early-warning system that saves lives and property,” explained researcher Yi Cui, an associate professor of materials science and engineering at Stanford. “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.”
The new system relies on an early-warning system based on an ultrathin copper sensor placed atop a conventional battery separator
The motive behind the new research was to address the issue of lithium-ion battery safety — which has gotten a lot of press in recent years due to high profile incidents, such as the Boeing 787 Dreamliner battery fire.
The press release provides more:
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’s damaged, the battery could short-circuit and ignite the flammable electrolyte solution that shuttles lithium ions back and forth.
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.
To address the problem, Cui and his colleagues applied a nanolayer of copper onto one side of a polymer separator, creating a novel third electrode halfway between the anode and the cathode.
“The copper layer acts like a sensor that allows you to measure the voltage difference between the anode and the separator,” Zhuo stated. “When the dendrites grow long enough to reach the copper coating, the voltage drops to zero. That lets you know that the dendrites have grown halfway across the battery. It’s a warning that the battery should be removed before the dendrites reach the cathode and cause a short circuit.”
“You might get a message on your phone telling you that the voltage has dropped to zero, so the battery needs to be replaced,” Zhuo said. “That would give you plenty of lead-time. But when you see smoke or a fire, you have to shut down immediately. You might not have time to escape. If you wanted to error on the side of being safer, you could put the copper layer closer to the anode. That would let you know even sooner when a battery is likely to fail.”
The new technology is detailed in a paper just published in the journal Nature Communications.
Useful research for sure. There’s no doubt that such a technology could find wide use, so long as it remains economical. In particular, electric vehicles could perhaps benefit greatly, especially as their sales (and, thus, accidents) increase.
Source: http://cleantechnica.com/2014/10/29/lithium-ion-battery-warns-fire-hazard-developed-researcher/
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