Thursday, December 31, 2009

"A Quantum Leap in Battery Design" 10 Times the Energy Density of Lithium-ion

Seriously disruptive technology.
From MIT's Technology Review:

Digital quantum batteries could exceed lithium-ion performance by orders of magnitude.

A "digital quantum battery" concept proposed by a physicist at the University of Illinois at Urbana-Champaign could provide a dramatic boost in energy storage capacity--if it meets its theoretical potential once built.

The concept calls for billions of nanoscale capacitors and would rely on quantum effects--the weird phenomena that occur at atomic size scales--to boost energy storage. Conventional capacitors consist of one pair of macroscale conducting plates, or electrodes, separated by an insulating material. Applying a voltage creates an electric field in the insulating material, storing energy. But all such devices can only hold so much charge, beyond which arcing occurs between the electrodes, wasting the stored power.

If capacitors were instead built as nanoscale arrays--crucially, with electrodes spaced at about 10 nanometers (or 100 atoms) apart--quantum effects ought to suppress such arcing. For years researchers have recognized that nanoscale capacitors exhibit unusually large electric fields, suggesting that the tiny scale of the devices was responsible for preventing energy loss. But "people didn't realize that a large electric field means a large energy density, and could be used for energy storage that would far surpass anything we have today," says Alfred Hubler, the Illinois physicist and lead author of a paper outlining the concept, to be published in the journal Complexity.

Hubler claims the resulting power density (the speed at which energy can be stored or released) could be orders of magnitude greater, and the energy density (the amount of energy that can be stored) two to 10 times greater than possible with today's best lithium-ion and other battery technologies....MORE

HT: Next Big Future who links to the PDF and posted a Christmas Eve follow-up:

The energy density and the power density of nano vacuum tubes in comparison to other energy storage devices (a). The volumetric energy density and the gravimetric energy density of nano vacuum tubes in comparison with combustion engines and several types rechargeable batteries, including those based on lead, nickel-cadmium, nickel-metal hydride, and lithium (b). Nano vacuum tube arrays are lighter and smaller energy storage devices than other batteries.

MIT Technology Review: A "digital quantum battery" concept proposed by Alfred W. H¨ubler and Onyeama Osuagwu at the University of Illinois at Urbana-Champaign could provide a dramatic boost in energy storage capacity--if it meets its theoretical potential once built.

(17 page pdf) Digital quantum batteries: Energy and information storage in nano vacuum tube arrays



December 24, 2009
Digital Quantum Batteries Managing Risk of a Quantum Engineering Age

Dr Alfred Hubler discusses the managing the risks of the high energy densities if digital quantum batteries are developed.

Could one use nano capacitors for energy storage, where dielectric breakthrough is prevented by quantization phenomena?

This is an exciting prospect. The introduction of digital batteries could spark an exciting transition from the nuclear age to a quantum engineering age.

The theoretical limit for electrostatic energy storage in quantum devices is very high. The energy density in heavy atoms, i.e. the ratio between the stored energy and atomic volume for an excitation from the ground state of heavy metal ions is 10,000 times higher than in hydrogen atoms. Based on this theoretical limit, the maximum density of retrievable energy in nano capacitors is comparable with the density of retrievable energy from nuclear reactions.

The rapid energy release of nano capacitors discharged by an electrical short makes them potent explosives, potentially exceeding the power of any chemical explosive. In contrast to nuclear explosives, the production of nano capacitors requires not radioactive substances but common, nonpoisonous, environmentally friendly chemicals. Without electrical charge, nano capacitors have no explosive power. In contrast to both nuclear and chemical explosives, simply using nano capacitors as batteries and slowly removing their charge as electrical current could easily and safely discharge them. In the discharged state, they could be shipped without safety concerns. At their destination they could be easily charged with electrical current. Even if an explosion were to occur, it would produce no radioactive waste, no long term radiation, and probably could be designed to produce no chemicals.

Technology to produce nano capacitors may already exist because similar quantum effects are used to keep charge separated in MTJ capacitors (used in MRAM), in flash drives and in laser diodes. In laser diodes, the recombination of electrons and holes is a forbidden transition. Therefore, the holes are long lived even if they are very close to the electrons. This leads to large electric fields. Literature data suggest that in standard laser diodes the electric field is above the breakthrough field of regular capacitors, and could be much larger. Conceivably, conventional flash drives could be used for energy storage, but they are not designed for this purpose: the substrates are thick and the energy to weight ratio is small. One could design large arrays of individually connected nano capacitors, to be charged and discharged one-by-one, similar to flash drives. In contrast to regular batteries, the output voltage would remain constant until the last nano capacitor is discharged. One could call these arrays of nano capacitors digital batteries....