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Graphene Ultracapacitor Could Shrink Systems

A more capacitor-like ultracapacitor could replace much bigger components

3 min read

23 September 2010—The ultracapacitor—the battery’s quicker cousin—just got faster and may one day help make portable electronics a lot smaller and lighter, according to a group of researchers. John Miller, president of the electrochemical capacitor company JME, in Shaker Heights, Ohio, and his team reported the new ultracapacitor design this week in Science.

Ultracapacitors don’t store quite as much charge as batteries but can charge and discharge in seconds rather than the minutes batteries take. This combination of speed and energy supply makes them attractive for things like regenerative braking, where the ultracapacitors would have only seconds to recharge as a car comes to a stop. But sometimes a second is still too long: Using nanometer-scale fins of graphene, the researchers built an ultracapacitor that can charge in less than a millisecond. This agility, its designers say, means that the devices could replace the ubiquitous bulky capacitors that smooth out the ripples in power supplies to free up precious space in gadgets and computers.

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A Circuit to Boost Battery Life

Digital low-dropout voltage regulators will save time, money, and power

11 min read
Image of a battery held sideways by pliers on each side.
Edmon de Haro

YOU'VE PROBABLY PLAYED hundreds, maybe thousands, of videos on your smartphone. But have you ever thought about what happens when you press “play”?

The instant you touch that little triangle, many things happen at once. In microseconds, idle compute cores on your phone's processor spring to life. As they do so, their voltages and clock frequencies shoot up to ensure that the video decompresses and displays without delay. Meanwhile, other cores, running tasks in the background, throttle down. Charge surges into the active cores' millions of transistors and slows to a trickle in the newly idled ones.

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