Improved High-Performance Energy Storage

Physicists at the University of North Carolina have developed new improvements for high-energy-density capacitors that can store up to seven times as much energy per unity volume as common capacitors. "The amount of energy that a capacitor can store depends on the insulating material in between the metal surfaces, called a dielectric. A polymer called PVDF has interested physicists as a possible high-performance dielectric. It exists in two forms, polarized or unpolarized. In either case, its structure is mostly frozen-in and changes only slightly when a capacitor is charged up. Mixing a second polymer called CTFE with PVDF results in a material with regions that can change their structure, enabling it to store and release unprecedented amounts of energy."

Comments

Wrong University

[jmcharry]

From TFA, it is North Carolina State University. You are about to be set upon by wolves!

polymers

[wizardforce]

CTFE Chlorotrifluoroethylene PVDF Polyvinylidene fluoride http://en.wikipedia.org/wiki/Polyvinylidene_fluori de

Vaporware...

[Rhys]

Key phrase from TFA:

"Their predictions of higher energy density capacitors are encouraging, but have yet to be experimentally tested."

Call me when they're being produced in something resembling quantity. Yeesh.

major faux pas in /. description of article

[Yonder Way]

The editors are asleep again. The summary says the discovery was made at University of North Carolina, which really surprised me because all of the good engineering is happening at North Carolina State University.

It might seem like a trivial slip but to those around here there is a pretty huge difference.

Oh yeah, and DUKE SUCKS.

Re:battery replacements?

[jcorno]

Don't get too excited. They're still about an order of magnitude away from lithium ion batteries. The power power density and durability are much better, but that doesn't mean much when it has to be 10 times as big.

*yawn* only seven times?

[syukton]

Call me when they're competing with MIT's carbon nanotube based ultracapacitors. Conventional ultracapacitors can achieve an energy density of 6Wh/kg, but the CNT ultracapacitors being researched and developed by MIT are claimed to achieve an energy density of 60Wh/kg (or, let's say, ten times more than this "new" capacitory developed by North Carolina State University).

Overview: http://lees-web.mit.edu/lees/projects/cnt_ultracap _project.htm
More-detailed Poster (PDF): http://lees-web.mit.edu/lees/posters/RU13_signorel li.pdf

Unity volume?

[jpellino]

Surely you mean "unit volume"

You misstate the physics...

[msauve]

Fundamentally, capacitors store electricity (electrical charge), batteries do not - they convert electrical energy into chemical energy in a reversible manner. The charge/discharge curves are very different, most batteries will provide a pretty steady voltage until the chemical energy is almost depleted - capacitors will exhibit a smooth drop in voltage as the electrical energy is removed. Batteries won't work in normal resonating circuits because they don't have exponential charge/discharge curves like capacitors. This is also the main reason that capacitors won't replace batteries for simple circuits - a battery can be equipped with a simple buck regulator and provide very acceptable service. Because of the exponential discharge curve of a capacitor, making effective use of its stored energy requires a much more complex (and costly) regulator.

While one can encounter "leaky" capacitors, that is not a necessary characteristic, and some commonly available ones do very, very well

Capacitors are not exclusively used for their ability to release energy quickly - high capacity ("gold" or "supercaps") ones are often used as backup power sources for low current applications (such as real time clock keepalive), due to the fact that they can be expected to have longer lifetimes than batteries.