Graphene battery demonstrated to power an LED

Mar 16, 2012 by Lin Edwards report
Schematic diagram showing the experimental setup of the device with Au-Ag electrodes. Image: arXiv:1203.0161v2

(PhysOrg.com) -- Scientists in Hong Kong have reported, in ArXiv, their experiments to make a graphene battery that they say generates an electrical current by drawing on the ambient thermal energy in the solution in which it is immersed.

Researchers led by Zihan Xu of the Department of Applied Physics and Materials Research Centre at the Hong Kong Polytechnic University, attached silver and gold electrodes to a , typically 7 mm x 7 mm in area, mounted on a . The assembly was then immersed in a saturated solution of copper chloride (CuCl2), and was found to produce an of 0.35 V. They also found that six assemblies arranged in series produced enough electricity to power a light-emitting diode (LED). The device continued to produce around the same for 25 days, but after a month it dropped to about 40 mV.

Graphene is a material that consists of a layer of carbon only one atom thick, and it has been the subject of intense research in recent years because of its unusual properties. One of these properties is an exceptionally high .

Xu and colleagues write in their paper that they think the voltage arises from the of the copper ions in the copper chloride solution, which they say is enough to knock electrons out of the graphene, and that these electrons then flow through the sheet. They noted that the voltage increases when the copper chloride solution is heated, and varies with its concentration.

Experimental setup of six graphene devices connected with a commercial LED before (a) and after (b) it was lighted up. Image: arXiv:1203.0161v2

The group also found the voltage increased when the assembly was exposed to pulses of ultrasound, and they say this lends weight to the idea that kinetic energy is the source of the voltage, since the ultrasound would increase the velocity of the . Small voltages were also produced with ionic solutions such as NaCl and CuSO4. The researchers also carried out control experiments to rule out the possibility that chemical reactions were responsible for the voltage generated.

Dr. Wanlin Guo, the graduate supervisor of one of Xu’s team (Guoan Tai), expressed skepticism at the proposed mechanism, and added that he had so far been unable to reproduce the findings in his own experiments, in which he used graphene sheets of varying sizes, mounted on varying substrates, and with different kinds of electrodes. He was unable to achieve voltages greater than around 0.1 mV.

In 2011, a research group led by Nikhil Koratkar of New York’s Rensselaer Polytechnic Institute also reported on experiments in which graphene was shown to generate a voltage when an ionic solution was made to flow over the sheets. Dr. Guo, of Nanjing University in China, also refuted these results and carried out experiments that showed the interaction of the ions in solution with the electrodes was responsible for the voltage, rather than any interaction with the graphene.

If Xu’s “graphene battery” is harnessing the of motion of the ions to generate electricity, this source of energy is essentially unlimited. The researchers say their experimental results provide a “huge breakthrough” in the research into self-powered technology.

Explore further: Carbyne morphs when stretched: Calculations show carbon-atom chain would go metal to semiconductor

More information: Self-Charged Graphene Battery Harvests Electricity from Thermal Energy of the Environment, arXiv:1203.0161v2 [cond-mat.mes-hall] arxiv.org/abs/1203.0161

Abstract
The energy of ionic thermal motion presents universally, which is as high as 4 kJbullet kg-1bullet K-1 in aqueous solution, where thermal velocity of ions is in the order of hundreds of meters per second at room temperature1,2. Moreover, the thermal velocity of ions can be maintained by the external environment, which means it is unlimited. However, little study has been reported on converting the ionic thermal energy into electricity. Here we present a graphene device with asymmetric electrodes configuration to capture such ionic thermal energy and convert it into electricity. An output voltage around 0.35 V was generated when the device was dipped into saturated CuCl2 solution, in which this value lasted over twenty days. A positive correlation between the open-circuit voltage and the temperature, as well as the cation concentration, was observed. Furthermore, we demonstrated that this finding is of practical value by lighting a commercial light-emitting diode up with six of such graphene devices connected in series. This finding provides a new way to understand the behavior of graphene at molecular scale and represents a huge breakthrough for the research of self-powered technology. Moreover, the finding will benefit quite a few applications, such as artificial organs, clean renewable energy and portable electronics.

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User comments : 24

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MR166
1.9 / 5 (14) Mar 16, 2012
If this was a thermal and not a chemical reaction, why did it stop after 25 days? Also, thermal reactions require a temperature gradient in order to work otherwise the laws of physics would be violated.

I give this article about as much credibility as cold fusion.
Skepticus
2.7 / 5 (7) Mar 16, 2012
Put the cell in a vacuum flash and a thermometer. If it is using thermal energy, then the cell temperature should decrease, otherwise, no cigars.
jalmy
1 / 5 (6) Mar 16, 2012
I swear this is the same article i read a week ago, I think it stopped due to degradation of the electrodes.
Jeddy_Mctedder
1 / 5 (7) Mar 16, 2012
Sterling engines require too much heat and thermoelectric materials seem particularly ineffixient at low temperatures.

At the low side of ambient waste heat below boiling water temperature, there is low hanging technological opportunity to move waste heat and harvest it for use in and enginea motor or for storage or recycling inro a heat cycle.

Violations of thermodynamics aside. This area of engineering and design is a big one ------ harnessing heat below 100 celsius.
kaasinees
1 / 5 (4) Mar 16, 2012
If this was a thermal and not a chemical reaction, why did it stop after 25 days? Also, thermal reactions require a temperature gradient in order to work otherwise the laws of physics would be violated.

I give this article about as much credibility as cold fusion.

The temperature difference between a few sheets is minor. But than again you can stack lots of sheets in one space. And that might be enough to power an LED.
jselin
not rated yet Mar 16, 2012
Maybe the voltage arises from some type of spontaneous intercalation?
Estevan57
2.6 / 5 (27) Mar 16, 2012
Dr. Wanlin Guo, the graduate supervisor of one of Xus team "(Guoan Tai), expressed skepticism at the proposed mechanism, and added that he had so far been unable to reproduce the findings in his own experiments, in which he used graphene sheets of varying sizes, mounted on varying substrates, and with different kinds of electrodes. He was unable to achieve voltages greater than around 0.1 mV."

Why did these people even publish? The graduate supervisor can't duplicate and they publish? Must be the FleischmannPons intitute of Hong Kong.
MR166
2.1 / 5 (22) Mar 16, 2012
Why did these people even publish? The graduate supervisor can't duplicate and they publish? Must be the FleischmannPons intitute of Hong Kong.

Perhaps they were trying to get some "Green Energy" funding from the Obama administration.
Tank
4.2 / 5 (5) Mar 16, 2012
Physorg, please say this is a joke that is couple of weeks early. Has anyone heard of galvanic corrosion? Dang in middle school I put two different metal rods in a lemon and lit up a tiny light. This is the problem with the development of places like China, etc. They have tried to make leaps and bounds so fast that they miss common sense.
antonima
1 / 5 (1) Mar 16, 2012
If this was a thermal and not a chemical reaction, why did it stop after 25 days? Also, thermal reactions require a temperature gradient in order to work otherwise the laws of physics would be violated.


The second law of thermodynamics has exceptions. This has been published as the 'fluctuation theorem' - Every system has some probability to have a spontaneous decrease in entropy, and some systems can be specifically designed for this purpose.

Tank: good one Tank
hanselda
5 / 5 (2) Mar 16, 2012
@antonima, fluctuation does not lead to macroscopic free energy. Till now there is NO violation of second law of thermodynamics observed.
And again, ArXiv does not really mean get published. This paper will hardy have any chance to pass peer-review. Every sensible physics student will be able to sense the violation of 2nd law. It is a shame for the university that they PR the result without questioning, just reflecting their lack of scientific idea and critical thinking.
MR166
2.5 / 5 (8) Mar 16, 2012
Fine, there is some probability of a spontaneous decrease in entropy. So I am going to stick some wires into what looks to be some 35mm film containers and wait for another Big Bang to happen.
Callippo
1 / 5 (5) Mar 16, 2012
Has anyone heard of galvanic corrosion?
I'm afraid, it's the most probable explanation of the whole stuff. It's virtually impossible to keep the silicon from solution with monolayer of graphene. What's worse, when I discussed this article first before few day, the preprint didn't contain any mention of some blind experiment (like the gold-silver cell without graphene). When I wrote, such a blind experiment should be checked at the very first place, then the preprint has been suddenly rewritten accordingly next day. It's quite strange story.
Callippo
1 / 5 (5) Mar 16, 2012
Till now there is NO violation of second law of thermodynamics observed.
What this graphene powered LED is supposed to do is, it should shine in visible light, while cooling itself bellow temperature of environment. Did we really never observed such a situation? In the last century so-called lime light has been used. The calcium oxide is candoluminiscent: when heated at high temperature, it begins to shine brightly, while cooling itself bellow temperature of environment. This is not violation of 2nd thermodynamical law? For example we know about thermoluminiscent pigments. These pigments glow in visible spectrum, when they're heated.
MR166
2.5 / 5 (8) Mar 16, 2012
"What this graphene powered LED is supposed to do is, it should shine in visible light, while cooling itself bellow temperature of environment."

If they manage to do this it will make Einstein look like a shoe shine boy.
Enrique_Cobas
Mar 16, 2012
This comment has been removed by a moderator.
Callippo
1 / 5 (6) Mar 16, 2012
If they manage to do this it will make Einstein look like a shoe shine boy.
Magnesium burns in air with a very intense brilliant light forming magnesium oxide (magnesia): Because of this, magnesium was used for making illuminating powders for flash-light photography. It was found that the color temperature of incandescent magnesia is 5000 °C, while the actual temperature is not over 2000 degrees. It means, the magnesium powder would lose its temperature spontaneously at 2000 °C, while heating the surrounding environment to 5000 °C. http://www.youtub...gNldBNWg
Eikka
3.7 / 5 (9) Mar 17, 2012
while heating the surrounding environment to 5000 °C


That's not how color temperature works.

Color temperature means that the spectrum peak happens at the same wavelenght where it would if the light was coming from a hot black body of that temperature.

A simple LED can have a color temperature of 5000 K and it won't heat its surroundings to 5000 K because it reaches a thermodynamic equilibrium at some point, where the incoming radiation matches the outgoing radiation. The wavelenght or the color temperature of the radiation is irrelevant.
Eikka
2 / 5 (4) Mar 17, 2012
What happens with the mangesium oxide is similiar to fluorescence, where the material has a specific emission spectrum that is different from a pure black body radiator.

Instead of sending out photons at all possible wavelenghts with a probability that looks like a bell curve, the curve is skewed some way or another, which makes it look like it's coming from a hotter or colder object than it really is. There are many materials that send out light at a lower color temperature than the light that hits them, and for one high-energy photon that arrives, they simply send out two or three low energy photons etc. etc.

Put simply, the temperature of an object is not necessarily related to the wavelenght of light it sends out, and the wavelenght of light hitting an object doesn't determine how hot it can get.
Callippo
1 / 5 (6) Mar 17, 2012
I'm just pointing to the fact, object can radiate the energy with frequency higher, than it corresponds its temperature, thus effectively cooling itself and violating the 2nd law of thermodynamics.
There are many materials that send out light at a lower color temperature than the light that hits them, and for one high-energy photon that arrives
Why not, but I'm not talking about these materials, but about materials, which are doing the opposite. Try to read before posting, Internet is already full of trivialities.
Eikka
3.3 / 5 (7) Mar 18, 2012
thus effectively cooling itself and violating the 2nd law of thermodynamics.


Again. That's not how color temperature works. An object does not "cool itself" when its color temperature is higher than it's real temperature. It just means that its emission spectrum is different from an ideal black body radiator.

The frequency does not matter in terms of temperature and thermodynamic equilibrium. An object can radiate in the gamma ray spectrum, and yet it will reach a thermodynamic equilibrium when placed in a box because the box will radiate back at infrared frequencies until the total energy flux is balanced and the two equalize in temperature.

It's about the energy carried, not the wavelenght of the radiation.
Graeme
not rated yet Mar 20, 2012
Even just putting silver and gold in electrolyte will give you a voltage. Silver is quite willing to react with Chloride, when there is oxygen around to help out there should not be any difficulty.
Invitro
not rated yet Mar 31, 2012
Isn't it a perpetual motion machine of the second kind?
Callippo
1 / 5 (3) Mar 31, 2012
Isn't it a perpetual motion machine of the second kind?
I'd guess, it's really rather a battery, than the Maxwell daemon. I'm opened to wild ideas of whatever kind, but this explanation looks most feasible for me. When I pointed in the discussion here, that the article lacks the notion of blind experiment, i.e. the voltage measurement WITHOUT graphene, then the notion of blind experiment had been added next day into new version of ArXiv article - the evidence of it is still hanging on the web. This is somewhat amateurish and suspicious behavior.
Callippo
1 / 5 (3) Mar 31, 2012
Another suspicious remark of one of authors is "Because it seems that this experiment does not agree with the second law of thermodynamics,we are busy with this big issue." It looks, like the Chinese weren't aware of this issue from the very beginning until they submitted their work to the Nature - again, such attitude looks somehow amateurish for me. Nature journal is traditionally very dismissive regarding the works, which do try to violate established physics. My article was fired with Nature editor immediately.