Graphene comes to the rescue of lithium-ion batteries
Remember the Japan Airlines plane that caught fire due to a malfunction with its lithium-ion batteries? That, and other fires in items such as hover boards and laptops, have cast a shadow over the battery technology. The technology is great; the fires, not so much.
Now a solution is at hand, and this could be a great breakthrough – and another bit of good news for those companies planning to produce lithium or graphite.
Researchers at Stanford University have been working on how to fix this problem and have developed a new kind of lithium-ion battery that automatically shuts down once it reaches a certain temperature and won’t switch back on until it has sufficiently cooled. And the solution involves the use of graphene
As for that JAL incident, this is how Scientific American recorded the event: “At 10:21 a.m. on January 7, 2013, about a minute after all 183 passengers and 11 crew members from Japan Airlines Flight 008 disembarked at Boston’s Logan International Airport, a member of the cleaning crew spotted smoke in the aft cabin of the Boeing 787-8. A mechanic then opened the aft electronic equipment bay of the plane, parked at the airport gate, and saw billowing smoke and flames coming from the batteries for the 787’s auxiliary power unit. He tried to use a fire extinguisher, but the blaze didn’t go out.”
Even after firefighters put our the blaze, the batteries were still giving off heat and appeared to reignite.
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That sent a lithium-ion scare around the world and last year many airlines refused to carry the batteries as freight, lest they ignite in the hold of an aircraft.
There have been other problems with the battery.
Last month there was a news report that, in Hollywood, California, a lithium ion battery burst into flames. Jordan Meshel, 14, had bought a new battery for his radio-controlled car and placed it on his desk to charge in his room. Within a few minutes the fire alarm went off: the batteries were on fire. Fortunately, the house had a fire extinguisher.
A few weeks earlier, The Washington Post reported that one teenager owned his hoverboard for only three days when it exploded beneath him. It was a problem that was not confined to that D.C. household.
Soon airlines banned hover boards. Online retailers such as Amazon and Overstock said they would no longer sell some brands. “And the U.S. Consumer Product Safety Commission announced Monday that it will be investigating the trendy toys in an effort to pin down the source of reports of 29 emergency room visits and at least 11 fires related to hoverboards”, reported The New York Times.
The problem: the rechargeable lithium-ion batteries in the foot-rests of the scooters. And the problem is that plenty of manufacturers (think China) have been making lithium ion batteries that were not of the highest standard, a fact that has tarnished the image of the technology.
Then the South China Morning Post reported that dozens of hoverboards were being seized every day at Hong Kong International Airport. “Some models of the self-balancing scooters have proven to be potentially hazardous, prompting the airport to tighten security checks to stop them from being loaded on to aircraft. They may be a popular Christmas present, but they raise alarm bells for airport scanners when they are detected hidden inside suitcases and hundreds of hoverboards have been consigned to the scrap heap this month”, the paper said.
Then last May, the Insurance Journal reported that at least 18 airlines had banned freight shipments of lithium-ion rechargeable batteries. And pilots were pushing for the cells to be taken off all passenger flights until they could be transported more safely.
Emirates, Cathay Pacific Airways Ltd., Cargolux Airlines International SA, and Qatar Airways Ltd., four of the world’s top 10 cargo carriers, removed shipments of bulk batteries from all flights last January. Singapore Airlines Ltd., another top-10 cargo airline, would not allow them on its passenger planes. Delta Air Lines Inc., American Airlines Group Inc., and United Airlines banned them from all flights.
There frights may be something of the past.
According to the release by Stanford University, their researchers have developed a thin polyethylene film that prevents a lithium-ion battery from overheating, then restarts the battery when it cools. The film is embedded with spiky nanoparticles of graphene-coated nickel. The new technology could prevent the kind of fires that have prompted recalls and bans on a wide range of battery-powered devices.
“People have tried different strategies to solve the problem of accidental fires in lithium-ion batteries,” said Zhenan Bao, a professor of chemical engineering at Stanford. “We’ve designed the first battery that can be shut down and revived over repeated heating and cooling cycles without compromising performance.”
As the university explains, a typical lithium-ion battery consists of two electrodes and a liquid or gel electrolyte that carries charged particles between them. Puncturing, shorting or overcharging the battery generates heat. If the temperature reaches about 300 degrees Fahrenheit (150 degrees Celsius), the electrolyte could catch fire and trigger an explosion.
To address the problem Cui, Bao and postdoctoral scholar Zheng Chen turned to nanotechnology. For the battery experiment, the researchers coated the spiky nickel particles with graphene, and embedded the particles in a thin film of elastic polyethylene.
“We attached the polyethylene film to one of the battery electrodes so that an electric current could flow through it,” said Chen, lead author of the study. “To conduct electricity, the spiky particles have to physically touch one another. But during thermal expansion, polyethylene stretches. That causes the particles to spread apart, making the film nonconductive so that electricity can no longer flow through the battery.”
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