Coming soon: the eight-hour notebook battery

Well, soon-ish

IDF Fall '04 New battery technologies have the potential to take notebook battery life beyond five hours, ultimately reaching eight hours of charge by 2010.

"When we talk to people about mobile computing, battery life is the thing they most want improved," said Anand Chandrasekher, general manager of Intel’s Mobile Platforms Group. "But delivering more is tough, technically."

He outlined a three-pronged approach to improving battery life: driving down power consumption at a silicon level; working on optimising power usage at a system level; and new battery chemistry to improve capacity.

He touched on two chemistries that will deliver significant improvements. The first is a lithium polymer technology from a company called Pionics, which involves improved anode and cathode materials, although more information than that is not available at this stage.

The second comes from a company called Zinc Matrix Power (ZMP), which has developed a rechargeable zinc-alkali battery which should withstand around 500 charge cycles.

Making rechargeable zinc batteries that can cope with more than around ten recharge cycles has proved a challenge for two main reasons: zinc oxide is highly soluble in alkaline electrolyte, and zinc recharges at about the same voltage that causes water to break down into hydrogen and oxygen.

Typically what happens is that the zinc anode dissolves as the charge is dispersed. then, when the battery is recharged and the anode reforms, it forms a needle-like deposit on the anode, called a dendrite. This gradually builds up over consecutive recharge cycles until it punctures the separator, shorting the battery out.

ZMP has introduced a zinc / plastic mix, which significantly slows dendrite formation. Happily, this also gets around the problem of hydrogen separation. More on that here (under the Zinc Solubility and Hydrogen Recombinance headings).

The company says that the batteries it produces this way have twice the charge capacity of same sized Li cousins, and as much as six times the run time.

"We've got it to 1,000 [recharge cycles] in the lab," explained Skip Zeller, president and CEO of ZMP. "In fact it seems to do better on a partial charge, unlike lithium batteries."

This is a good thing, because to fully recharge the battery, users will need to plug it in overnight. However, Zeller says, just one hour of charge time will give it juice for six hours of run-time.

Chandrasekher also announced the third iteration of the ACPI specification (Advanced Configuration and Power Interface) from the Mobile PC Extended Battery Life working group, but said that further industry collaboration is needed.

ACPI is an open industry standard for OS-directed configuration and power management on laptops, desktops, and servers. ®

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