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back to article Hong Kong scientists claim 'self-charging' graphene battery

Scientists from Hong Kong Polytechnic claim to have demonstrated a graphene-based battery that harvests ambient energy and turns it into electricity. The claim, however, has been questioned by another member of the university. In their paper, published on Arxiv here, the researchers say they were able to get around 0.35V for 25 …

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Bronze badge
Holmes

IANAC but...

Isn't the fact that it stops working after 25 days a bit of a giveaway that it's a chemical reaction?

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Re: IANAC but...

that or it just sucked the life force out of everything around it.

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Anonymous Coward

Re: IANAC but...

I was thinking something along the same lines. It sounds like electrons flowing from one electrode to the other, which no doubt leads one of the electrodes to ultimately decay. Or maybe I'm remembering these things from school days incorrectly? It's quite normal for a conductor's properties to change depending on conditions like heat, but would this affect voltage or just resistance? Hmmm... physics and chemistry classes seem so long ago.

Interesting if it's repeatable though.

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Re: IANAC but...

They didn't say that it stopped working after 25 days, they said that they observed a voltage over 25 days.

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Anonymous Coward

Re: Re: IANAC but...

No Paris Hilton angle then?

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Re: IANAC but...

Actually they did say pretty much just that.

"the output voltage (Vop) generated by this device loaded a 220 kΩ resistor was around 0.35 V, which could be maintained about 25 days [...] The value dropped to about 40 mV after about one month."

-robin

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Re: IANAC but...

I've worked with people like that...

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Coat

Re: IANAC but...

I stand corrected.

In hindsight, I should not only have read the bloody article, but I should have read the bloody paper too.

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Go

Collecting ambient energy has been possible for over a century.

Take a metal sheet, some wire and a capacitor.

Suspend metal sheet so it isn't grounded (the higher from the ground the better), attach a wire and hook up one end of the capacitor. Attach a wire to the other end of the capacitor and plant the wire into the ground.

Grab your multimeter, measure the voltage across the capacitor. Note your figure. Come back in 15 minutes and repeat. What is the voltage now?

A little something Tesla patented way back when. http://www.google.com/patents/US685957

The only issue is converting this stored energy into a form which is usable - that's the tricky part!

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Holmes

There is no Maxwell Daemon

>Collecting ambient energy

You never, never, ever "collect ambient energy". You can merely use the [potential] energy differences between two points. Like in building a dam.

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Coat

Re: There is no Maxwell Daemon

True, the potential difference in the charge from the upper atmosphere versus the ground. Basically we're living on a giant capacitor.

However, if the definition of ambient holds true: http://dictionary.reference.com/browse/ambient, then it is still ambient, as we are completely surrounded by the electrical potential difference between that which is above and below us.

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Sounds to me like this is working the same way as lumps of sacrificial zinc on the hull of an iron ship. It is a battery, yes, but it's not self-charging (it is self-destructive).

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Gold badge
Meh

A fairly obvious observation

Are any of the components being *consumed*?

If (as they say) they are collecting the kinetic energy of the ions there should be no *irreversible* chemical changes going on in the cell and all elements should be at their same concentrations as the ions pick "re-charge" from the ambient room temperature

Note there are a number of groups working on "environmentally powered" sensors for things like structural monitoring. Major methods use vibrations "harvested" from PZ films and thermoelectric stacks operating on temperature differences.

Extraordinary claims require extraordinary *proof*.

*Might* be real but highly suspicious.

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Re: A fairly obvious observation

Indeed, it sounds as though they've claimed to do something like breaking the second law of thermodynamics, or recruiting Maxwell's demon.

However, a wind turbine merely extracts useable energy from the ambient environment, so why not.

However, if it's science, then the same thing should happen when someone else does the experiment, and apparently it hasn't.

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Thumb Up

Re: A fairly obvious observation

Upvoted for referencing Maxwell's demon. I haven't seen him around in a while.

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Anonymous Coward

The problem with trying to turn ambient energy into something useful is that it’s random:

Stick the battery into a vibrator? ENDLESS POWER!

Sorry.

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The Hong Kong researchers claim that they by using different metals at each end of the graphene – gold at one end, silver at the other – they observed a voltage flowing in one direction.

This is worrying as voltage never flows. If they mean a current then how much ?

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How much current? Ohm's law says 0.35v / 220kΩ = 0.0016mA

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Isn´t 0.35V in the range of normal electrode potentials? Ag/AgCl is a fairly popular couple and Cu(i)Cl is known to do all sorts of things like dissociate into Cu(ii) and metallic Cu(0). Incidentally, the standard potential for Cu(ii) to Cu(0) is 0.34V.

(http://www.wiredchemist.com/chemistry/data/electrode-potentials-acidic)

I would have a close look at those electrodes - and get my experiment *successfully* repeated before making outlandish claims.

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@MadChemist

I had a quick look at the full paper and it's rather hard to see what is being exposed to electrolyte.

The electrolyte mostly being used is Cu(II) Cl2 but the suggestion seems to be that it's the graphene being exposed whilst the gold and silver electrodes are sealed away from the electrolyte.

My guess would be a slight leak, maybe impurities in the silver or some slight copper plating and the Cu(II)/Cu(0) pair.

Scarcely worth speculating if it can't be repeated

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Meh

isn't this waht maxwell's demon is all about?

http://en.wikipedia.org/wiki/Maxwell's_demon

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Besides

If the battery was taking non-chemical energy from the solution shouldn't there be a measurable drop in temperature - and a spike in voltage if heated?

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And as for the "it works faster when it's heated" argument...

...isn't it true that some chemical reactions are endothermic and can absorb thermal energy (such as that supplied by a burner) during the reaction? Therefore, it may be possible that additional or improved reactions may be taking place under the heat, producing the results claimed while still being chemical in nature.

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Anonymous Coward

Gravity Battery

Since Gravity seems to be close to constant here on Earth, why not use it to generate the prescious energy?

All ya need is something that you know always gets effected by gravity, to have it move in such a way that it forward bias's itself -imo Circles are great, I think.

"I Live in the middle of nowhere-ville, it's the center of the universe, it's why I moved here, cause it's great."

If ya add a small charge to it for the bias, technically you should be able to control the entire process with a stupid 9 volt battery linked to a counter or synchronized counters (the tuning of the forward bias), and it's electronics linked or output proper to SCR's for however much current is needed.

The other thing to think about is.

"I used to be able to lift 20 nabbies on the end of my shovel, in 24 hours, I can take it."

how an electric motor works. if planets are moving around the sun, it's a matter of having a way to make one body's coil cutting through the flux of another body's permanent magnet. Then knowing the frequencies to Wrap that coil for the juice.

I drink too much beer to know the answers to these ideas.

It's why I enjoyed the PARIS / vulture project. God damn that rocks.

You got my lazy American respect on that. I can make a working telegraph from scratch, but I can't do what yo did. Well, I mean you could hand it to me and say do xyz. But that's not what I meant. I did some work with digital delays for a bit. Massive ratwire, so there's that. it's pretty bad, lots of ittty bitty wires.

HOPEFULLY - dropping 2k bombs on people to spread democracy won't be the ultimate use of either technology (gravity or PARIS). ( I can visualize a giant PARIS capable of carrying a 2k car. -- lots and lots of paper mache with a super coating) These wars are seriously retarded now. Both our countries are being pelted by more and more civil rights loss. If I am reading things right neither of our country's citizens want a global government. It's the psycho's running the governments. We should be trying to work out a way that our power (not to be confused with this "stupid" smart grid. 'Oh Yeah I have the box now' can't be wrecked by the sun. But I also did electrical, so if that happens, I know how to bypass it but... anyway I think it's stupid. It's possibly dangerous, as we are all already weakened by the financial monetary terrorists.

ps: didn't that guy flying with wings look like the monkeys the wizard of oz? lol - it made me sick to my stomach for a second there. I see them saying hoax now, but if he really did fly, man.. that's everyone's dream

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Anonymous Coward

Re: Gravity Battery

Say what!?!?

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Re: Gravity Battery

You not been taking your meds. Am I right?

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Go

Re: Gravity Battery

"Since Gravity seems to be close to constant here on Earth, why not use it to generate the prescious energy?"

Yes. There are devices out there that use gravity to generate energy. You might have heard of them. They're called "dams".

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Re: Gravity Battery

To bring your comment full circle: when the flying man falls, use his precious energy ;-)

(Also, I really hope you come back and re-read your own comment when you are sober!)

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Facepalm

Sound more like....

Cold Fusion 2.0, or just about as useful....

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Gravity Battery

It already exists...and is referred to as potential energy, a function of a mass raise to a height. Have you ever pulled the weights up on a cuckoo clock? Or swung a weighted pendulum? Or climbed the stairs? In all three cases you're putting energy into something, your height above ground. Gravity gives it back to you when you come down.

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Re: Gravity Battery

But therein lies the rub. It takes more energy to get the thing up than you get back when it comes back down. If you could break some scientific laws and get a way to either employ gravity-based energy without motion or to find a "over-unity" way to raise a weight...

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