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Li-ion battery triples notebook operating life

Posted: 16 Apr 2007 ?? ?Print Version ?Bookmark and Share

Keywords:Li-ion battery for notebook computer? notebook computer battery with threefold longer life span? Li-ion battery for laptops with faster charge time?

Startup Boston-Power Inc. has fielded a Li-ion battery for notebook computers that promises a faster charge time and a threefold longer life span than existing batteries.

The news comes as established vendors are poised to roll battery chemistries that they say will deliver about 10 percent more battery life than today's batteries, but with a potential trade-off of longer charge times and shorter life cycles.

Laptop suppliers are anxious to apply new battery chemistries or any other technology that extends the operating life of their systems, but they hold out little hope for major leaps in battery performance until fuel cells are commercialized. For now, some laptop suppliers are considering Boston-Power's battery.

"Boston-Power is picking up on key points that users can understand. These are some of the biggest things people care about in batteries," said Sara Bradford, an energy and power systems analyst for Frost & Sullivan. The startup's big challenge, she said, is that "consumer markets are the most competitive to enter."

Notebook makers welcome the stepwise improvements. OEMs and market watchers agree that bigger performance gains will arrive with the commercialization of fuel cells for portables. But Kamal Shah, mobility-enabling initiative manager with Intel Corp., was recently quoted at a conference as saying that fuel cells will not be ready for notebooks until at least 2010.

"It was nice to see them being realistic," said John Wozniak, a battery specialist at Hewlett-Packard Co. (HP). "Fuel cells are getting more miniaturized and efficient, but there are environmental and economy-of-scale issues to resolve before we put them in a commercial notebook. Fuel cells in the portable space still have problems with heat, their need to 'breathe' and other issues."

Boston-Power's Sonata battery promises to deliver 1,000 charge/discharge cycles without degrading cell performance. That's about three times the lifetime of current batteries. The net result is that high-end business users who consume two or three batteries with every notebook computer will be able to have one battery that lasts the life of their notebook.

Lampe-Onnerud: Boston-Power's battery will 'last as long as the computer.'

"This battery is reliable in a way consumers have never seen before. Consumers will see a battery that lasts as long as the computer," said Christina Lampe-Onnerud, CEO of Boston-Power.

In addition, the Sonata battery can achieve an 80 percent charge in as little as 30mins and a full charge in 1hr without degrading cell performance. Current batteries typically take as much as 1hr to reach 80 percent power in a fast-charge cycle that can degrade cell performance by 60-80 percent within 300 charge cycles.

"That's a big sensitive issue for the industry right now," said Wozniak, who appeared on stage with Boston-Power executives as they unveiled the battery during the Demo conference in California.

Lampe-Onnerud said she expects HP will be the first notebook maker to use the Sonata battery, probably in one or two high-end business notebook products.

HP's Wozniak said he has received samples from the first volume preproduction run at Boston-Power's joint venture factory (with an unidentified partner) in Shenzhen, China. HP will spend several weeks testing the products before it makes a decision whether to use them. "Nothing has been approved" yet, Wozniak said, but "the early data looks good."

Keeping his options open, Wozniak said he intended to visit battery maker Zinc Matrix Power as part of his trip for the Boston-Power launch.

Boston-Power has applied for five patents on Sonata. The company claims the battery differs from existing Li-ion batteries in as many as 30 ways, including its chemistry formulation and processing as well as the interaction of its chemicals and metals.

The company would discuss only one of those attributesa unique cell format that is twice the size of standard Li-ion cells. The traditional lithium cell structure comprises two cells and looks like two alkaline batteries welded together at the top and bottom. "Others have to match two cells perfectly to make sure there is no current or heat loss. We don't have that problem, so we can control impedance in a way no one else can," said Lampe-Onnerud.

The mechanically larger cells mean Sonata batteries have more space to pack in chemicals, opening the door to as much as 30 percent more battery life per charge than batteries using traditional cells. "Their mechanical concept gives you more room inside the can," said Wozniak. "The energy density is not that much different from standard Li-ion, but mechanically, they can use their space better."

The Sonata battery's mechanically larger cell opens the door to more battery life per charge.

To get the extra battery life, notebook OEMs will have to adjust the control voltages they use, which will probably only require minor changes to system firmware. Boston-Power is opting to forego the extra battery life initially in an effort to make its batteries a drop-in replacement for existing notebooks. "We want to make it easy for OEMs to adopt this product," said Lampe-Onnerud.

Nevertheless, Boston-Power will charge "a small premium" it would not specify for the product.

The startup closed a $15.6 million Series B investment round in January, bringing total investment to date to $23.6 million. The new funds will help it ramp capacity. Boston-Power's joint-venture plant in Shenzhen, China has the capacity to serve at least one or two lines of notebooks. The startup plans to set up at least one more factory.

Although most of today's batteries are produced in Japan, China could be a significant player in the battery sector. "My bet is that you will see faster innovation and quicker turnaround of prototype concepts coming out of China than Japan over the next five years," said Lampe-Onnerud.

New chemistries
The Boston-Power batteries arrive as existing battery makers are gearing to deliver a class of products that use nickel instead of cobalt compounds in their cathodes to deliver a 10 percent increase in battery life per charge. The batteries generally step up from about 9.5W-hrs to 10.5W-hrs, said Wozniak.

The batteries, from manufacturers such as Sanyo and LG Electronics, also typically raise charge voltages from 4.2V to 4.3V, a move already being supported in the latest battery charger ICs. Panasonic, which is already shipping its new batteries in its own systems, bucks the trend, maintaining the 4.2V charge voltage, but lowering their discharge cutoff from 3.7V to 2.67V.

"In some cases, these batteries may have longer charge times or shorter life cycles. My expectations are being lowered by the vendors," said Wozniak, who added that he was expecting samples in January, but hadn't seen them yet.

Boston-Power would not say whether nickel cathodes are a part of its new chemistry.

The nickel compounds face longevity and performance issues. But lithium-doped nickel oxide typically delivers an energy density of 220mA-hr/g, compared with 140-160mA-hr/g for the lithium cobalt used in today's batteries.

Researchers are experimenting with new metal compounds in the battery anode as well, but there is little consensus about which metals are best. Products using the new anodes may not emerge for three to five years, said Lampe-Onnerud.

"Energy density of Li-ion batteries has been increasing at about 7 percent per year over the past few years through gradual improvements in battery chemistry," wrote Jim Tully, chief of research for Gartner Dataquest in an e-mail exchange. "Several companies are talking about introducing batteries with higher energy density, but I don't see any evidence that this is any more than tinkering around the edges. The big opportunity for a step change in energy density really comes with fuel cells, probably combined with ultracapacitors for handling high power pulses."

Wozniak said Zinc Matrix Power will deliver notebook batteries this year. But it is not yet clear what changes notebook makers will have to make to accommodate them or what benefits they will offer, he said.

'Like pillows'
HP participated two years ago in a demonstration of a tablet PC running on a lithium sulfur battery from startup Sion Power Corp. But HP says it has had no contact with the company since the demos shown at the Windows Hardware Engineering Conference in 2004.

"Their batteries have real good gravimetric density, but in terms of volume they are like pillows," Wozniak said. "They are light but bulky, and that doesn't bode well when you are trying to slim down your notebook form factor. In terms of safetyin some ways, it's better, and in other ways, it is scarier than Li-ion."

- Rick Merritt
EE Times

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