Researchers try to take cell phone batteries beyond breaking point
By Mike Hughlett
When you’re marveling at what your cell phone can do – play videos and music, surf the Web – but can’t figure out why its confounded battery drains so quickly, consider this classic scene from the original “Star Trek”:
Captain Kirk harangues Scotty, the beleaguered chief engineer, to squeeze more power from the starship’s engines. Scotty protests, but still manages to extract a wee bit more power without blowing up the ship.
For this, Scotty should be named patron saint of engineers who design the batteries for cell phones and other portable electronic devices.
Battery experts say that like Scotty, they’re nearing the limit of current battery technology, known as lithium ion. “We are at the point where you can’t get much more out,” said Jai Prakash, a chemical engineering professor at the Illinois Institute of Technology.
So researchers are ramping up efforts in new power technologies, particularly fuel cells, which convert small amounts of a fuel, usually methanol, into electricity.
Fuel cells promise more power and less time spent recharging phones. But right now they’re still too costly to make and too big to fit in many gadgets.
While engineers continue to do what they can with lithium ion, these batteries have become a focus of concern.
Battery-related recalls of laptops and cell phones have been accelerating in recent years. About 9.6 million Sony-made batteries were recalled this year after reports of laptop computers smoking or bursting into flames.
Though overheating incidents are rare, lithium-ion batteries pack a particularly strong punch when they blow. That’s because they store so much energy in such a small space. But that’s also why they’ve been such a hit in consumer electronics.
Lithium is one of Earth’s most reactive metals. Thus, batteries containing lithium-based chemical compounds store twice as much energy as nickel-metal-hydride batteries, once the standard for portable electronic devices.
Sony introduced the lithium-ion battery in the early 1990s. Since then, battery makers have made them even better. Energy levels in lithium-ion batteries improve about 5 percent to 10 percent each year, said Jason Howard, energy technologies manager for Motorola Inc.’s mobile phone business.
For Motorola, the world’s second-biggest mobile phone maker, that means its phones run longer between recharging.
While 5 percent to 10 percent gains made in lithium-ion energy content sound impressive, the speed of microprocessors and the storage capacity of disk drives in electronic devices double every 18 months to two years.
The battery craftsman is the cold voice of reality, reminding gadget designers that there are limits. “There’s an old maxim that engineers will consume all the energy you give them and scream for more,” Howard said.
They’re screaming loudly nowadays. Larger phone screens and colored screens, too, consume more power. More important, as phones are increasingly used for entertainment, they’re being used more often and drained of their batteries more quickly. Similar things can be said for laptops.
Battery researchers expect to squeeze 10 percent to 30 percent more energy out of lithium-ion technology.
Still, “there’s only so much energy in those (chemical) materials (in batteries), and we are not far from their theoretical limit,” said Jerry Hallmark, energy technologies manager at Motorola Labs in Tempe, Ariz.
Hallmark is working on the fuel cells that many see as a successor to batteries in portable electronic devices.
A battery is a canister of chemicals that react and produce electricity. In a fuel cell, energy is also converted into electricity via a chemical reaction.
Unlike batteries, though, fuel cells don’t need to be recharged, a process that takes time. They need to be refueled, but that can be done quickly by inserting a fuel cartridge into a phone or laptop. Perhaps more important, fuel cells are expected to provide two or three times more energy than a lithium-ion battery, Hallmark said.
Methanol, also known as wood alcohol, is used in most experimental fuel cells for phones and laptops. Methanol is highly flammable but can be packaged safely in cartridges for fuel cells, battery experts say.
Still, fuel cells face big hurdles and are a few years away from widespread commercialization. They are costly to make; their electrodes are usually fashioned from platinum, an expensive metal. Plus, fuel cells will have to shrink before they can be widely used in electronic devices.
Motorola has invested an undisclosed amount in Tekion, a British Columbia-based company that thinks it has a leg up in downsizing fuel cells.
The company’s technology comes from Richard Masel, a chemical engineer at the University of Illinois at Urbana-Champaign and Tekion’s senior technical adviser. Tekion also has an office in Champaign.
Masel’s approach uses formic acid for fuel, which allows Tekion to decrease the overall size of its fuel-cell system, said Neil Huff, Tekion’s chief executive.
It’s about half as big as a methanol-based system, said Huff, who anticipates a marketable product by late 2007 or early 2008.
The cell phone is a fuel-cell maker’s toughest challenge because it’s the smallest gadget. Yet it’s also the most pervasive, with about 1 billion expected to be sold globally this year.
“The cell phone is the Holy Grail, but it is the most difficult,” Huff said.
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