Dec 23 2009

A Quantum of Solace for Energy Storage?

Posted by: Jonathan Marshall

Albert Einstein famously dismissed the emerging physics of quantum mechanics as "very impressive" but "not yet the real thing."  He just couldn't bring himself to believe its wierd implications, which continue to spark scientific and philosophical debate.

Good thing the young turks of quantum physics pushed on, for it became an essential tool for understanding semiconductors, the basis of the electronics revolution of the late 20th century. Today, scientists are exploiting its strange implications to study quantum dots, quantum computers, and now "digital quantum batteries."

Two scientists at the University of Illinois at Urbana-Champaign have drafted a largely incomprehensible new paper claiming that a miniaturized array of "nano vacuum tubes," using quantum principles, could create energy storage devices with several times the capacity of lithium batteries or standard capacitors. Or to put it another way, for any given energy capacity, they could be shrunk into a much smaller and lighter package.

Just as important for many applications, their rate of charging and discharging is claimed to be orders of magnitude greater than current batteries. That would be a boon in electric cars, where the ability to deliver power on demand would guarantee high acceleration.

The paper claims further that "cheap environmentally friendly materials can be used to fabricate" the devices using standard techniques for making integrated circuits, and that the devices "can hold electric energy without any losses for many years."

In a normal capacitor, electrical energy is stored in a field between two conducting plates separated by an insulator. The closer the plates and the thinner the insulator, the more energy it can store--but thinner insulators are more prone to breakdown under high voltages, making it tough to design small, high-capacity devices.

The key to the new quantum batteries--which exist only as concepts so far--is exploiting quantum mechanical effects that prevent short-circuits between the two electrodes, which are spaced only 10 nanometers (about 100 atoms) apart.

The scientists have applied for funding to the Defense Advanced Research Projects Agency to develop a prototype. The concept has generated a lot of skepticism, but at least one MIT engineer, who is working on competing devices, declared himself "cautiously intrigued."

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