Paper supercapacitor could power future paper electronics

May 21, 2010 By Lisa Zyga feature
Photos at left and center show the paper supercapacitor printed on Xerox paper. The right photo shows the paper supercapacitor printed on newspaper. Image credit: Liangbing Hu, et al. ©2010 AIP.

(PhysOrg.com) -- All those paper transistors and paper displays that scientists have been designing can now be powered by an onboard power source, thanks to the development of a new paper supercapacitor. Designed by researchers at Stanford University, the paper supercapacitor is made by simply printing carbon nanotubes onto a treated piece of paper. The researchers hope that the integrated design could lead to the development of low-cost, disposable paper electronics.

In the paper supercapacitor, all the necessary components are integrated onto a single sheet of paper in the form of single walled carbon nanotubes (SWNTs). High-speed printing could be used to print the SWNTs directly onto a piece of paper - anything from paper to newspaper and even grocery ads will work. At first, the researchers found that the SWNTs were so small that they penetrated the paper through micron-sized pores, which would cause the device to short-circuit. To solve this problem, the researchers first coated both sides of the paper with polyvinylidene fluoride (PVDF), which blocked the pores but still allowed for electrolytes to be transported through the paper. As such, the treated paper could function as an membrane and separator without short-circuiting.

“The key design is that SWNTs stick well on paper and do not penetrate through paper completely to avoid shorting,” Yi Cui of Stanford University told PhysOrg.com.

Once the SWNTs were printed onto the treated paper, they experienced strong bonding forces similar to those experienced when writing with a pen or pencil on paper. Even when rubbed or subjected to tape, the SWNTs remained attached to the paper. After printing SWNTs on both sides of single sheets of paper, electrolyte was loaded to form a supercapacitor. The SWNTs served as both the electrodes and current collectors in the supercapacitor, which had a capacitance of about 3 F/g. The device also showed an excellent cycling stability, with very little loss of capacitance after 2500 cycles. The researchers say the same concept could be extended to make batteries, as well.

The fully integrated supercapacitor is based on an earlier version that the researchers made, in which nanomaterials were coated separately onto different anode and cathode substrates and then assembled together with a separator. The advantage of the new integrated structure is that it allows for high-speed printing, which greatly reduces fabrication costs and brings disposable, flexible, and lightweight electronics closer to reality. Cui said that, in the future, the researchers plan “to use this new design for real applications.”

Explore further: See-through, one-atom-thick, carbon electrodes powerful tool to study brain disorders

More information: Liangbing Hu, Hui Wu, and Yi Cui. “Printed energy storage devices by integration of electrodes and separators into single sheets of paper.” Applied Physics Letters 96, 183502 (2010). Doi:10.1063/1.3425767

4.6 /5 (33 votes)

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User comments : 10

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Topperfalkon
5 / 5 (1) May 21, 2010
I guess this is the next step towards truly minimally-intrusive power supplies for medical devices such as pacemakers, right?
Alburton
5 / 5 (1) May 21, 2010
3 Farad/gramm??? is this possibly correct?
usual capacitors are in the microfarad range!
TEH AWESOME IF TRUE!
ZeroX
3.7 / 5 (6) May 21, 2010
I guess this is the next step towards truly minimally-intrusive power supplies for medical devices such as pacemakers, right?

It's rather target for wide range consumer electronic, rather then pacemakers, where the large volume capacity, high energy density, stable voltage and low (self)discharge rate is required. The parameters of supercapacitors are exactly the opposite.

http://www.mpower...one3.gif

BTW The capacitance in range of 5 Farads per gram is still too low, as we have supercapacitors with 150 farads per gram already - and they're not used anyway. Whereas lithium batteries with pseudo-capacitance values in range 600 to 800 Farads per gram are used in the AA configuration commonly.

http://www.resear...ate.html
jselin
5 / 5 (1) May 21, 2010
Just don't touch both sides of the paper at the same time :)

neat idea...
laserdaveb
May 21, 2010
This comment has been removed by a moderator.
HealingMindN
not rated yet May 21, 2010
Disposable carbon nanotubes? On polyvinylidene fluoride paper? What are the environmental implications of that? Before I start throwing away paper cameras, cellphones, gps and the like, is there a way I can learn to print my own? I would make greeting cards with an OLED screen / camera teleconference combo. What about carbon nanotube tattoos?
MarkyMark
5 / 5 (1) May 22, 2010
What about carbon nanotube tattoos?


This does pose the question about just what could one day be possable. Tattooable Mobile Phones, Watches etc?
Alizee
May 22, 2010
This comment has been removed by a moderator.
Tank
not rated yet May 23, 2010
Voltage is key. The operating voltage of these supercaps are usually well less than 1 volt. Once you start stacking these things in series to get the working voltage you need all those farads go away. Not to mention these may be fine for storage but they will not work for replacing capacitors that are close to the operating components. The ESR (equivalent series resistance) and DF (dissipation factor) are terrible for supercaps. A supercap is closer to a battery than it is to a capacitor. This might, might work out as a battery for these devices, but it will not work for the capacitance needs close to the chip.
LKD
1 / 5 (1) May 24, 2010
Carbon tube development, 500 billion. Paper manufacturing development, 100 billion. Having a soda cup from McDonald's that senses what kind of beverage it has within then displays it on the lid instead of hoping the serving robot depressed the little plastic bubble right? Priceless. (OK done joking)

The future aways looks amazing with these research projects showing up in the news more and more.
Scalziand
not rated yet May 24, 2010
3 Farad/gramm??? is this possibly correct?
usual capacitors are in the microfarad range!
TEH AWESOME IF TRUE!


The article left me a little confused as to whether it's 3 F/gram of SWNT or 3F/gram of printed capacitor, including the paper.
ricarguy
1 / 5 (1) May 28, 2010
I agree with Tank, above. I don't recall the formula off the top of my head, but energy is proportional to C * V^2. So the working voltage of the capacitor is critical, and that is not mentioned in their testing.

Interesting research.
Alizee
May 28, 2010
This comment has been removed by a moderator.