Nanotech

for

Super-capacitor

Written by

Wang Jing Yuan

Instruction

1.What is Nanotechnology?

Nanotechnology, sometimes shortened to "Nanotech", refers to

a field whose theme is the control of matter on an atomic and mo-

lecular scale. Generally nanotechnology deals with structures 100

nanometers or smaller, and involves developing materials or de-

vices within that size.

Nanotechnology is extremely diverse, ranging from novel ex-

tensions of conventional device physics, to completely new ap-

proaches based upon molecular self-assembly, to developing new

materials with dimensions on the nanoscale, or the scale of nothing,

even to speculation on whether we can directly control matter on

the atomic scale. (1)

2.What are capacitor and super-capacitor?

A capacitor is a passive electronic component that stores en-

ergy in the form of an electrostatic field. A capacitor consists of two

conducting plates separated by an insulating material called the di-

electric. The capacitance is directly proportional to the surface ar-

eas of the plates, and it is inversely proportional to the separation

between the plates. Capacitance also depends on the dielectric con-

stant of the substance separating the plates. (2)

Super-capacitors, also known as Electric double-layer capaci-

tors, electrochemical double layer capacitors (EDLCs) or ultra-

capacitors are electrochemical capacitors that have an unusually

high energy density when compared to common capacitors.(3)

How does a common capacitor turn to a super-capacitor? Be-

cause we change the material of dielectric and plates with the help

of nanotech. As the equation shows us E depends on capacitance, C

and voltage, V. And C depends on surface area of plates, A and dis-

tance between two plates, d. If we can increase A and decrease d as

much as possible, we can have much energy stored in our capacitor.

Reference

1.Nanotechnology. Web Site: http://en.wikipedia.org/wiki/Nanotechnology

2.(24 May ). Midmarket CIO Definitions. Retrieved November 23, 2008, Web site: http://

searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci211742,00.html

3.Supercapacitor. Web Site: http://en.wikipedia.org/wiki/Supercapacitor

4.Mullaney, Michael (August 13). Beyond Batteries: Storing Power in a Sheet of Paper. from

http://news.rpi.edu/update.do?artcenterkey=2280

5.R&D of supercapacitors in Skeleton NanoLab. Web site: http://www.skeletonnanolab.com/

Supercap.html

Figure 1. http://www.nanochimie.com.my/021.gif

Figure 2. http://spie.org/Images/Graphics/Newsroom/Imported/1047/1047_fig1.jpg

Figure 3. http://electronics.howstuffworks.com/capacitor.htm/printable

Figure 4. http://commons.wikimedia.org/wiki/

Image:Maxwell_supercapacitor_MC2600_series_2600F.jpg

Figure 5. http://www.aviransplace.com/2005/12/24/

Figure 6. http://www.fullboost.com.au/forum/showthread.php?p=31870

Current Research

In August 2007, a research team at RPI developed a paper battery with aligned carbon nano-

tubes, designed to function as both a lithium-ion battery and a supercapacitor (called bacitor), using

an ionic liquid, essentially a liquid salt, as the electrolyte. The sheets can be rolled, twisted, folded, or

cut into numerous shapes with no loss of integrity or efficiency, or stacked, like printer paper (or a

Voltaic pile), to boost total output. Further, they can be made in a variety of sizes, from postage stamp

to broadsheet. Their light weight and low cost make them attractive for portable electronics, aircraft,

automobiles, and toys (such as model aircraft), while their ability to use electrolytes in blood make

them potentially useful for medical devices such as pacemakers. In addition, they are biodegradable.

(4)

The Estonian company Tartu Technologies developed supercapacitors from mineral based carbon.

These nonactivated carbon are synthesised from the metal- or metalloid carbides, e.g. SiC, TiC,

Al4C3, etc. as claimed in US patent 6602742 and WO patent 2005118471 . The synthesised nanos-

tructured porus carbon, often called Carbide Derived Carbon (CDC), have surface area about 400 m²/

g to 2000 m²/g with specific capacitance up to 100 F/mL (in organic electrolyte). They claim a super-

capacitor with a volume of 135 mL and 200 g weight having 1.6 kF capacitance. The energy density

is more than 47 kJ/L at 2.85 V and power density of over 20 W/g.(5)

The company Reticle claims to be able to make supercapacitors from activated carbon in solid

form. This substance they call consolidated amorphous carbon (CAC). It can have a surface area ex-

ceeding 2800 m2/g and according to US patent 6787235 may be cheaper to produce than aerogel car-

bon.

Figure 1. Scanning electron mi-

croscope picture of 1000nm

polystyrene beads arranged in an

opal structure.

Figure 2. Lithium cobalt oxide (LiCoO2) in

Figure 3. equation of energy storage in capacitor Figure 4. MC and BC series supercapacitors (up to 3000

farad capacitance) produced by Maxwell Technologies

Figure 5. Paper Battery

Future Prospect

Ultracapacitors: the future of electric cars:

"The big problem has always been the battery and its limits,"

says Clifford, ZENN's founder and CEO in a phone interview.

"This new technology is a 180-degree shift that represents the end

of fossil fuel as a transportation fuel."

That's because the same ultracapacitor technology could be

used across the grid to provide cheap electric storage for wind and

solar power, he says. In turn, this process could power millions of

ultracapacitor vehicles with no emissions at all. With the cars' fast-

charge capability, recharging stations could pop up to help make

even longer trips routine. And the company is now nearing com-

mercial production of its new "electrical energy storage unit" or

EESU

Figure 6. Future electric car