Graphene-based "battery" that runs solely on ambient heat

[Cherryman]

Researchers at Hong Kong Polytechnic University claim to have invented a new kind of graphene-based "battery" that runs solely on ambient heat.

Graphene in new ‘battery’ breakthrough? - physicsworld.com

[1203.0161] Self-Charged Graphene Battery Harvests Electricity from Thermal Energy of the Environment



Just to inform.

[wyndbag]

When will I be able to pick one up at Walmart?

[MonsieurM]

Thank you CherryMan

check out the golden tractate Thread...quite a useful info

[Slider2732]

Zihan Xu and colleagues made their battery by attaching silver and gold electrodes to a strip of graphene – which is a film of carbon just one atom thick. In their experiments, the researchers showed that six of these devices in series placed in a solution of copper-chloride ions could produce a voltage of more than 2 V. This is enough to drive a commercial red light-emitting diode.

I have trouble with this.
If they can't get 2V from 6 cells anyway then they are doing something very very wrong !
Take for example, plain water cells. Burnt copper on one electrode, galv steel as the other. You can get 0.75V at 2ma without issue, from a pills bottle and adequate electrode sizes for the cell size.
So, even plain ole' water, 6 cells with non exotic metals, will get you 4.5V @ 12mA !
You can run a Slayer Exciter on that and light 100 LED's !
Long term running issues ? Even mine have been going since November of last year running LED oscillators and b_rads similar cells have topped 18 months.
Smaller amount of solution ? no problem, lay the electrodes flat and put them in a couple of mm's of water, separated by a piece of kitchen roll.

So, the main peer reviewed result here is the graphene. What is it doing ?

[ibpointless2]

I have trouble with this.
If they can't get 2V from 6 cells anyway then they are doing something very very wrong !
Take for example, plain water cells. Burnt copper on one electrode, galv steel as the other. You can get 0.75V at 2ma without issue, from a pills bottle and adequate electrode sizes for the cell size.
So, even plain ole' water, 6 cells with non exotic metals, will get you 4.5V @ 12mA !
You can run a Slayer Exciter on that and light 100 LED's !
Long term running issues ? Even mine have been going since November of last year running LED oscillators and b_rads similar cells have topped 18 months.
Smaller amount of solution ? no problem, lay the electrodes flat and put them in a couple of mm's of water, separated by a piece of kitchen roll.

So, the main peer reviewed result here is the graphene. What is it doing ?

The main reason for the low voltage is due to them using gold and silver electrodes. What's odd is that the graphene should be shorting out the two electrodes. I think this is just a type of galvanic battery but since it uses electrodes that dont corrode as easy it will last for a long time. It reminds me of Karpens pile.

[NickZ]

Slider:
I would like to see a circuit running 100 leds off just a 4.5 volts, 12 mAs.
Just would like to know if it's really true, or not. As placing the 6 cells in series can yield 4.5 but not also the 12 mA. As the 2mAs per cell are either placed in series or parallel, but not both. Or have the mAs ALSO summed up as well, on your cells? As they have sometimes done on some of mine cells.
The thing that I'm also trying to get at is: What is the MINIMUM voltage/current needed to run the Dr. Stiffler type oscillator?
NickZ

[Slider2732]

Mostly, my point was about 6 of anything that use exotics of this caliber, to only produce enough oompf to light a red LED.
But partly, if its a step toward a solution, or a property discovery of graphene it's fine by me, perhaps the way it was touted was the mind spark.
Gold, silver, carbon nanotubes and more - there's probably some jealousy mixed in too lol
It just doesn't seem like an effective route for the materials used.
Like saying, take 8lbs of uranium, mix 1lb of gunpowder with 487000 match heads and throw a match at it. Stand back while the explosive force from ignition pops the lid off a jam jar

4.5V @ 12mA is quite possible.
See: Huge Exciter Tower - YouTube
or, Hartley Oscillator Replication - YouTube
or, Jonny's 2cm Micro Slayer Exciter.ASF - YouTube

As to output from even the same water, here's my vid of 6 LED oscillators doing that: Power Pill - 6 water powered oscillators - YouTube

Mind you, just a Ground outside and no conventional power input can light an LED wirelessly:
Zero input voltage wireless - now no wall adapter ! - YouTube

So, I just hope you see why there would be confusion about 6 cells and only enough about them to light a directly connected red LED on its own

[mikrovolt]

good info slider,

I wanted to make a distinction catagorically where some of this stuff is going.

several big companies last year went in the same direction as
laser sabre and many others variants, they helped make change happen.
some senarios believe 300 volts driving series leds HV
one big change was from buck to boost.

LIGHTFAIR 2011: High-Voltage DC LED Pendant Light - YouTube
look for 100 watt street lights,
what will they do with all those buck parts lots of videos. ( change happened)
Videos - Lighting Solutions - TI.com

In another video the third speaker with the red shirt explains how to overcome problems with
HV led strings using mosfets in a constant current loop. important as you design strings
minmizing hot spots because limitations of series strings and voltage drops..
In the TI video " How to connect multiple LEDS" this explains how to fix.
There are power supplys that use this current control method.

In contrast, the small batteries, low voltage using
energy harvesting we are having trouble making use of
the high efficiency boost converters such as the video light fair 2011.

so the small world has a large challenge
it has a different pathway than the grid
and it uses completely different circuits.
Some radiant energy circuits also making progress
with handling this problem low voltage. This distinction with how
the small power cells can use altenative solutions to also make a significant contribution
this is an ongoing concern that is why I make the distinction.

Special thanks to all those with
3V or less projects who are finding ways to use low voltage.

[NickZ]

Guys:
Although some videos are showing the lighting of leds while drawing very low mAs. But, they are using 1.5 batteries as a source which can have as much a 3 amps of current, and are not just using 12mA to start with, as with our cells. The draw is one thing, but is not the same as the total output of the source.
Our homemade cells may put out most any voltage, up to 12v, or so, but, they don't have much power behind them.
So, when I say that the I'd like to see a 4.5 v, 12mA circuit running 100 leds, that is where I was coming from, and Not by using a 1 to 3 amp AA battery to make it all work.

I understand that some amazing things are possible, even at very low mAs, but I've been trying to get my dry carbon/aluminum cells to work with a simple Jtc, but without the use of salts in the electrolyte. I have not been able to do it for very long. So, I'm now using ocean salt water in my cells, and have been able to light an led, for what is now 3 days, so far.
Now the the trick when using salts, is to keep it all from turning into mush.

Slider: the "zero input wireless power" video is not being factual, as your hand and body are then substituting your normal power supply (wall adaptor), ground. And are drawing parasitic energy from the house wiring.
I'm sure that you know that now, but may not have known it, then. As you don't need any circuit to light the led on the Av plug, if you just hold it onto the outside ground. It won't do that by itself without you holding it, and your body is acting as the second house wiring ground. So, the "zero input" is not actually what is really happening in that case.

Nick