Search for a better battery keeps going and going

Lithium-ion batteries may eventually give way to tiny fuel cells.

By , Staff writer of The Christian Science Monitor

Cellphones and laptop computers are so useful because they've cut the cord. Powered by tiny, lightweight batteries, they operate for hours far away from any power outlet.

Today these and other portable devices largely run on lithium-ion batteries, which pack more electrical punch per pound and square inch than earlier nickel-based rechargeables did. But the dangers and limits of this technology were exposed last month when Dell and Apple asked customers to return nearly 6 million lithium-ion laptop batteries made by Sony Corp. that could overheat and start a fire. In a much smaller recall, Matsushita Electric Industrial Co. also said last month that it would recall 6,000 similar batteries used in its Panasonic laptops sold in Japan because of concerns that they might overheat.

While the recalls embarrassed some of high-technology's biggest brand names, they aren't likely to change the way portable devices are powered – at least in the short term, say industry observers. Lithium-ion (li-ion) battery technology, introduced to consumers in 1991, still has plenty of room to improve in both safety and performance, while better alternatives using different chemistries, including long-touted fuel cells, still aren't ready for prime time.

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Last week, a consortium of battery manufacturers met to hammer out new design specifications for li-ion batteries, including improved safety standards. The hope is that the standards will be accepted and adopted in a matter of months, says Kimberly Sterling, a spokeswoman for IPC, the electronics standards association in Bannockburn, Ill., that sponsored the meeting.

The rechargeable li-ion batteries found in nearly all laptops, cellphones, and other portable devices can overheat or even catch fire if tiny metal fragments, left over from the manufacturing process, get into the electrolyte, the medium through which charged particles flow between a battery's positive and negative sides.

The metal fragments lodge in tiny pores in the plastic separator between the battery's positive and negative sides. That causes short circuits that may lead to dangerous overheating. These concerns were the apparent cause of the recent recalls.

"The only thing that should move in a lithium battery are the lithium ions," the electrically charged atoms, says Steve Carlson, president and CEO of Optodot Corp., in Boston, which is developing a new battery separator. "You don't want to have any tiny particles in the electrolyte moving around."

Optodot hopes to make batteries safer in two ways, he says. The company's separators are made of an inorganic material that, unlike plastic, can't melt or shrink. And, using nanotechnology, the separator's pores are about five times smaller than those in other separators, too small for the metal fragments to lodge in them. His company's product, not yet on the market, is being evaluated by a number of manufacturers, Mr. Carlson says.

"There's a need now for second-generation designs. And I think that's what these [recall] events bring out," Carlson says. "We need a better separator, we need a better electrolyte. It's all open for better design." He expects li-ion batteries to be even more powerful in the future and able to be recharged many more times before wearing out.

Other chemistries could be used to create safer batteries, but so far they don't provide as much power or operating time in such a small, light package. That makes li-ion attractive, despite safety concerns.

"The [li-ion] chemistry has some intrinsic safety issues that need to be dealt with," says Ahmad Pesaran, a principal engineer at the US government's National Renewable Energy Laboratory in Golden, Colo. But it's still going to be the "dominant" technology for years to come, he says.

Most li-ion batteries contain a cobalt-oxide catalyst, but at least one manufacturer uses a different formula that includes lithium iron phosphate in batteries for rechargeable power tools, Dr. Pesaran says. Lithium iron phosphate trades off some performance in exchange for safety, he says. Manganese, silver-zinc, vanadium, tungsten, and titanium are among other materials that are or could be used in li-ion batteries.

The US Department of Energy has so much faith in the future of li-ion that it's the only battery technology the department is funding as it develops a power source for future electric vehicles, Pesaran says. Toyota is already testing a li-ion battery in its Vitz automobile, a version of the Toyota Yaris sold in Japan. (Today's hybrid cars use rechargeable nickel-metal-hydride batteries.)

Meanwhile, the quest for an even better portable power source goes on. The prospects for tiny fuel cells, which aren't rechargeable batteries but can be "refuelable" and provide large amounts of electricity, may have brightened last week. A research team at Arizona State University (ASU) said it has created a hydrogen-powered fuel cell that could power laptops and small electric devices safely for three to five times longer than li-ion batteries.

"I think it will be very safe for two reasons," says Don Gervasio, a chemist at ASU and the research study leader. First, the solution the hydrogen is stored in isn't flammable: "You can take a lit match and put it out in it," he says. And while hydrogen can be explosive, in the fuel cell it is almost immediately consumed to make electricity as it's released from the borohydride solution. "[T]he amount of hydrogen will be minuscule at any given time, so that should be very safe," he says.

The ASU fuel cell's key advance is that it contains chemical additives that keep its borohydride solution from developing solids that "start gunking up the works," Mr. Gervasio says. He expects a commercial product using this technology to be at least four or five years away.

As people surround themselves with more devices containing batteries – and someday fuel cells – that store a lot of energy, they should remember that these kinds of devices already play a large role in every day life, says Levi Thompson, a professor of chemical engineering and director of the Hydrogen Energy Technology Laboratory at the University of Michigan in Ann Arbor.

"Everything has a hazard. It's just managing it," Dr. Thompson says. "Gasoline can be hazardous if not handled properly." Each new technology has risks associated with it, he says. It's the job of engineers to assess these risks and devise ways to eliminate them. "Obviously, the consumer has lost some faith in lithium-ion batteries. It's unavoidable. It's like a recall for an automobile. But the reality is that overall, it's a very safe technology," he says.

People who live in densely populated Asian cities would love to have li-ion batteries to power bicycles and small scooters because they last longer and weigh one-fourth as much as bulky lead-acid batteries, Carlson says.

Li-ion is "eventually where they want to go for automobiles, but they don't have the safety and they don't have the low cost yet," he says. "It's a developing technology. It's only been out 14 years ... you have to work through the safety and the cost."

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