As this definition indicates, graphene can only be one atom thick, otherwise it is not graphene!
What about the dielectric of such a material with an atom of thickness like graphene ... (?) I would answer that a dielectric of an atom with thickness eh bèh it must have a fairly low breakdown voltage .
I think you confuse capacitor and supercapacitor. It's technically different, the supercapacitor is really technically between the capacitor and the battery, with an electrolyte and electrodes made to have the largest surface possible, but in 3D, not a flat surface, so that the ions penetrate into the electrode, while adhering to its surfaces.
The SkelCaps don't really use graphene, but "Carbide-Derived Carbon (CDC), which can effectively be represented as an assembly of curved graphene flakes."
But as it says in the big file on supercapacitors, there are several techniques for making graphene electrodes and the fact that it consists of a single layer of atoms is an advantage when we assemble full of layers of graphene to make an electrode (and certainly not a single sheet of graphene):
http://www.supercondensateur.com/dossie ... aphene-ntcTo represent the potential benefit of using graphene layers over activated carbon, one can compare it with sheets of paper and a piece of wood; the sheets of paper being ultimately only very thin layers of wood. To create the most holes, the thinnest possible, in a given volume of wood, is it preferable:
- create lots of holes in a piece of wood using a mini drill, or by cracking the wood with successive impacts?
- or take many sheets of paper and crumple them to make large pellets, then compress them to reduce the volume?
The first solution resembles the case of activated carbon, while the second solution resembles the case of 3D graphene. Presented like this, it seems obvious that using 3D graphene is a better solution to obtain supercapacitors capable of storing a large amount of energy.
Graphene combines good electronic conductivity with a large specific surface (theoretically 2670 m² / g). One of the problems with graphene is its tendency to re-stack when overlapping several sheets of graphene, thus recreating graphite.
To overcome this problem, several techniques can be used [12]:
Creation of 3D graphene: the graphene sheets are crumpled together, as we would to make large balls of paper.
Use of the electrolyte to separate the graphene sheets.
Use of carbon nanotubes which are interposed between the graphene sheets, forming pillars which prevent the re-stacking of the graphene sheets.
Here is what a graphene electrode can give:
It's cool to boast of having 4500 Farad in a condo, if it's only to be able to apply a µV to it before it slams, it's not going to take us far.
You saw it yourself, the SkelCap 4500 Farads has an operating voltage of 2,85V. ???
your argument on "power density" VS "energy density"
This is not an argument, I explain things as they are, because obviously you had confused the two.
As it stands, with the results currently obtained, what total thickness is there of wound in these ultracapacitors? Certainly not 1 atom.
No, much more than one atom, as explained above.
And can we run a car with a voltage of 2,85 V? I would love to but I doubt it! Mr. Green
Current electric cars use batteries made of lithium-ion cells.
A lithium-ion accumulator has a nominal voltage of 3,6 or 3,7 V. It is the series connection of several Li-ion accumulators which makes it possible to obtain a battery with a higher voltage.
It's the same for supercapacitors. If you put 2 supercapacitors in series, the voltage will double. Capacity will decrease, however, but that's another story.
Here are 48V and 160V modules at Skeleton Technologies
http://www.skeletontech.com/modules
And then there are already electric supercapacitor buses, including the recent Bolloré BlueTram. So it works without problems ...
)
The same goes for the first wire on graphene ultracapacitors! ;)
