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Lithium-ion batteries pack extra power, challenges
January 19, 2013
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SEATTLE: The prospect of flying in a so-called plastic airplane was already unnerving for some. Now there’s the added concern of Boeing’s 787 Dreamliner using the same kind of batteries that used to overheat and ignite laptops made by Dell, Hewlett-Packard, Apple and others. Battery mishaps led to the plane’s grounding this week by US and European regulators.

Lithium-ion batteries are state of the art, producing the most energy in the lightest package at an acceptable price.

Problems


But they have had problems and continue to challenge engineers to manage the temperature generated in their chemical reactions, particularly as larger versions are produced for vehicles and now airplanes.

“It’s clear that there are some issues associated with thermal management,” said Donald Sadoway, a battery expert and the John F. Elliott Professor of Materials Chemistry at the Massachusetts Institute of Technology.

Since Sony began manufacturing them in 1990, lithium-ion batteries have led to a revolution in consumer electronics. They allow companies to build lightweight phones, cameras, power tools and other gadgets that run a day or more on a single charge.

In a phone, the batteries are thin and the heat is dissipated by the front and back of the case, which act like cooling fins, said Sadoway.

It’s a different story when you’re talking about batteries that are nearly twice the size of a car battery, like those used in the 787.

Tesla roadsters addressed the issue by using thousands of small, finger-sized batteries, clustered together. Now larger batteries are being used in cars such as Toyota’s plug-in Prius.

Boeing is the first company to use lithium-ion technology for the main batteries in a commercial airplane. The supplier of those recently also won a contract to upgrade the international space station to lithium-ion batteries.

Safety

Safety remains a concern, though, especially if manufacturers try to cut costs. Sony learned this the hard way in 2006. Errant metal flakes inside some laptop batteries it produced caused them to short-circuit, leading to sudden and sometimes spectacular fires. This resulted in recalls of more than 7 million batteries around the world, affecting major computer companies using Sony batteries.

“That’s a concern this industry has: You’re building a very energetic device; you’d better do it well or you’re going to have problems,” said Vince Battaglia, a specialist in battery design at the Lawrence Berkeley National Laboratory in California.

So how do the batteries work? Here’s how he would explain it to a lay person:

“It consists of two electrodes that each accept lithium. But one does it more easily than another. ... You get a voltage difference because of that relationship. You can use that energy and control it by discharging the battery at whatever (level) you want.”

The breakthrough with lithium-ion batteries was in the electrolyte material. Up until 1990, batteries were water-based. Researchers at Berkeley found that using an organic electrolyte led to dramatic increases in energy density, or the amount of energy in the package.

Lithium-ion batteries such as those used on the 787 have safeguards, such as controllers that trigger a shut-off if temperatures rise too much; vent built-up pressure; and prevent the batteries from bursting into flame.

A Boeing executive said the 787 has a redundant safety system with four controllers on the batteries, although that’s apparently not enough to prevent incidents and satisfy regulators.

Research continues into improving lithium-ion batteries, but the technology is now mature, said Jonathan Posner, associate professor of mechanical engineering at the University of Washington, who called the technology “a logical choice” for the 787.

“I don’t think Boeing would have used it if it wasn’t mature,” he said.

Posner said Boeing seems to have “an engineering issue that just has to be resolved. But I would be surprised if they don’t continue to use lithium-ion batteries in the 787.”

Different materials can be used in these batteries, some safer than others. Based on information posted on its website, Boeing supplier GS Yuasa appears to be using lithium cobalt oxide cathode material, which is the original material used by Sony.

“From a safety point of view, that’s not the best,” said Ji-Guang Zhang, a researcher at the Pacific Northwest National Laboratory in Richland, Wash. He said cobalt oxide batteries ignite at lower temperature than lithium batteries made with other materials, such as iron phosphate.

Supplier GS Yuasa declined to discuss whether the batteries in question use cobalt oxide and referred questions to its partner Thales Group, which didn’t promptly respond. Still, it’s all relative.

Gas

“Theoretically, it is safe,” Zhang said. “I think it is not less safe than a gasoline-powered engine. ... Gas is much easier to burn than batteries.” Battaglia said iron phosphate “has been known to sort of be safer.” But he added that “nothing is safe you’ve still got a lot of energy and an electrolyte in there that’s flammable.”

So should people feel comfortable flying in a plane with these batteries?

“Everybody in there has a lithium cobalt oxide in their pocket, so it’s sort of a matter of scale or engineering,” Battaglia said.

One option for Boeing could be to revert to an older, safer type of battery, but it would be heavier. While nickel-metal hydride batteries the type used in the Prius hybrid would weigh about 50 percent more, they’d add a relatively small amount of weight to the overall airplane, Sadoway said.

“It’s not as though we’re talking about making the plane incapable of getting off the ground,” he said.

Nasa is planning to install batteries in the International Space Station that use the same technology as the ones that grounded Boeing’s 787 Dreamliner fleet this week and are made by the same company.

Boeing is the prime contractor for the space station and is responsible for integrating hardware and software from many suppliers. In November, GS Yuasa Lithium Power of Japan won a contract to provide lithium ion batteries that eventually will help power the space station.

Boeing referred questions to Nasa. Josh Byerly, a NASA spokesman at the Johnson Space Center in Houston, said the batteries for the space station use the technology employed by the Dreamliner batters, but are “radically different.”

Byerly said the battery would not be installed for several years and would be tested rigorously beforehand.

“Anything that goes up to the space station has got to be tested,” he said.

Nasa will follow a Federal Aviation Administration inquiry into the safety of the lithium batteries but would make no immediate changes, he said.

“We’re going to pay attention to Boeing’s investigation,” Byerly said. “Right now, there’s no impact whatsoever.”

The lithium batteries made by GS Yuasa are getting a close look from federal investigators who want to know what caused two of them to overheat in two separate incidents 10 days apart in Boeing’s flagship aircraft.

The FAA grounded the Dreamliners Wednesday soon after the two Japanese airlines took their fleets out of service.

The agency’s emergency directive cited the potential of damage to the plane’s structure and electrical systems by heat, smoke and flammable liquids released by a battery fire.

FAA tests in 2004 and last year showed that lithium battery fires could burn as hot as 2,000 degrees Fahrenheit, well past the melting point of the composite material that makes up half the aircraft.

Days earlier, FAA Administrator Michael Huerta and Transportation Secretary Ray LaHood assured the public that the plane was safe.

New technology


Nasa is looking to new technology to power the space station. It orbits the Earth every 90 minutes and is powered by solar panels, but needs batteries when the Earth blocks the sun. The lighter, more powerful lithium batteries will replace nickel metal hydride batteries that have been used by NASA for decades.

Boeing designers abandoned proven battery technology with the Dreamliner, a calculated risk.

“If there appears to be something better that achieves some of your objectives, engineers will want to use it,” said John Logsdon, professor emeritus of political science and international affairs at George Washington University and a member of the panel that investigated the Columbia space shuttle accident in 2003.

Nasa and Boeing have conducted extensive tests of the batteries at the Glenn Research Center in Cleveland and at the Crane Naval Base in southern Indiana.

Tom Miller, an aerospace engineer at the Glenn Research Center, said the protections are built into the batteries to prevent short-circuits or heat buildup that can cause the batteries to ignite. They’re also encased in a tougher package that could contain a fire.

“The basic chemistry has been tested,” Miller said. “It’s all been safe at this point.”

Logsdon said that the combination of the Dreamliner problems, plus tests already planned by Nasa, “is going to make these extremely safe batteries by the time they get into orbit.”

“I don’t see any particular cause for concern now,” he said. “It’s better to find it out when you can land the plane than be 200 miles above the Earth.”

On Thursday, Rep. Chaka Fattah, D-Pa., wrote to NASA Administrator Charles Bolden requesting that the agency help the FAA figure out what happened to the Dreamliner’s batteries. He cited NASA’s role in assisting Toyota fix acceleration problems in its vehicles that led to a recall in 2010.

European air-safety officials followed their American counterparts’ lead Thursday by grounding Boeing 787 Dreamliner jumbo jets after a series of worrisome incidents aboard the new aircraft.

The European Aviation Safety Agency, or EASA, announced that it was adopting the Federal Aviation Administration’s directive, issued Wednesday, ordering all 787s taken out of service. Jeremie Teahan, a spokesman for the EASA, said the action was taken “to ensure the continuing airworthiness of the European fleet.”

As a practical matter, the decision by European regulators will affect only two 787s being used by the Polish airline LOT. But the move increases pressure on Boeing, which insists that its new passenger jet is safe but has promised to work with the FAA to resolve any concerns.

Doubts about the 787’s safety grew after a fire aboard a plane parked at Boston’s airport and an emergency landing by an All Nippon Airways flight whose crew reported a strange smell and noticed indications of a problem with a lithium-ion battery.

The FAA’s directive was issued less than a week after US transport officials deemed the 787 safe to fly. The agency said that Boeing now had to “address a potential battery fire risk in the 787.”

Teahan said the EASA would “carefully monitor the situation and is prepared to provide any support the FAA may require in their investigation.”

MCT

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