Assuming both technologies hit their limits at the nano-scale which will store more energy per volume/mass and which will have more power per volume/mass? I think capacitors have the advantage that the structure is fixed, ie. only electron charge is moving, whereas for batteries ions are moving which can wreck the structure of the battery over time, but can capacitors surpass batteries at the nano-scale?
Both are equivalent. Both store electrons in the valence shell of atoms. In cause the potential is created by the macroscopic separation of atoms while in the second is is microscopic(on the atomic scale). You could image the chemical bonds as a sort of capacitor. The difference is that in the case of a capacitor a large number of electrons can be "stored"(there is actually no storage of electrons but just a displacement which is why capacitors block DC) quickly released due to the mobility of the carriers. This is more difficult in chemical reactions. Chemical reactions generally can hold higher energy densities(think of TNT) due to the shear number of atoms used(compared to the number of electrons on your standard cap)
Ultimately one would expect the two phenomena to merge since they are based on the same fundamental physical principles(one of electron mobility). You can already see the phenomena overlap with plate capacitors and solidstate batteries or electrolytic capacitors and dry cell batteries.
Capacitors generally depend greatly on the material configuration but a counter example are tantalum caps.
Imago Scientific, my particular suicide mission into nanotech, has recently gone up for liquidation. The VCs, Draper Fisher Jurvetson and the usual crowd, rode that one pretty hard, expecting nanotech to be the next Web. Sorry, boys. The new boombust is social networking.
Here's some physics news that blurs the line you just drew:
Two rubidium atoms are combined into a molecule that exhibits long- term charge separation; the molecule is polar. Granted it must be ultracold and one atom is in a Rydberg state, but if the effect can be extended to shirtsleeve conditions the distinction between battery and capacitor might go away.
Well, lets see, one electron has a mass of about 10^-31. Therefor there are about 0.5*10^31 electrons in your "pound". There are 29 electrons in a copper atom so this equates to 0.5*10^31/29 copper atoms. A copper atom has a mass of 63*1.6*10^-27 kg so 0.5*63/29*10^4 ~= 10^4 kg.
So besides the fact that your "pound" of electrons would require a huge amount of copper we are not even considering the fact that only the valence electrons would play any part in conductivity.
If your wondering why I went through this mess it is to get you to realize that a "pound" of *free* electrons would be quite useless much less a pound of bound electrons.
Maybe someone will figure out how to confine a "pound" of free electrons in a small space using a magnetic field but it would take quite a force to keep them together... probably more energy than man has ever or will ever create.
The fact is that electrical conduction is a chemical process. The difference between the two is the type of chemical bonds in play.
I think "limits at the nano-scale" could mean that the technology would run out of atoms to create more surface area ie. for a capacitors "plates" or basically structuring the matter as much as possible down to the atomic/molecular scale. I guess it would be better to state that instead of saying nano-scale..
I think what you mean, given your lack of intellect, is that there is no flow of atoms or molecules. In a battery the electrolyte functions to prove easy mobility for electron migration but it is no less the same fundamental principles at work.
So here's your argument:
Electrons in a capacitors don't form chemical bonds
There is no "flow" of "matter" in a capacitor
Is this correct?
Maybe when you realize that electrons form bonds with atoms you might start to figure out why capacitors and batteries are different. It has nothing to do with the erroneous things you believe but the strength of the bonds used. In the case of a capacitor the chemical bonds are very weak and electrons can easily migrate from atom to atom and extra electrons can be forced in the atomic lattice(go read up on valence band theory). For batteries, The chemical bonds are much stronger and require a chemical reaction to break the electrons free. This necessitates the mobility of the atoms as now they are required to move(since the electrons are stuck to them, unlike conductors).
The whole point is that electrons have to move to prove the current. The principles at work are fundamentally the same but function differently due to the different materials used(and in some cases there is some overlap). I'm sorry you can't understand it. You should have paid attention phys 101b.
No. A battery has a more or less constant voltage which means you can use the full capacity. A capacitor adheres to E=0.5F * V^2 which means that the voltage has a direct relation with the energy stored. This makes it very hard to charge and discharge a capacitor efficiently.
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
Jamie is right. When you charge and discharge a battery, the chemical composition of its electrodes changes. When you charge and discharge a cap, no molecules change their chemical composition. That is precisely the difference between a capacitor and a battery.