It's claimed quantum capacitance depends on material density of states.

https://en.wikipedia.org/wiki/Quantum_capacitance ​

Is there a materials or substances which have infinitely high or infinitely low density of states?

What is a negative quantum capacitance?

Do I understand it correct that high quantum capacitance reduces overall energy which could be stored in a capacitor while negative quantum capacitance increases total energy stored?

The link is

https://en.wikipedia.org/wiki/Quantum_capacitance

 

Truly infinitely high, no, but practically, a metal does it very well.

 

Infinitely low, it's just a matter of wording, because an insulator behaves like a semiconductor where you can't add nor remove charges at the potentials you use it - but then you would include its thickness to the capacitor's insulation, not to the electrode, so you wouldn't call that "quantum capacitance".

The link is

https://en.wikipedia.org/wiki/Quantum_capacitance

 

Truly infinitely high, no, but practically, a metal does it very well.

 

Infinitely low, it's just a matter of wording, because an insulator behaves like a semiconductor where you can't add nor remove charges at the potentials you use it - but then you would include its thickness to the capacitor's insulation, not to the electrode, so you wouldn't call that "quantum capacitance".

Are you sure metals suppose to have very high quantum capacitance? It's said they have very high density of states and quantum capacitance is connected to situation when electron is transferred from material with high density of states to another material with much lower density of states (such as 2DEG). From this I can conclude that if we attempt to transfer electron to a material with very high density of states (such as a metal), very small if any quantum capacitance would be observed. And you claim metal's quantum capacitance is effectively infinite. Could you explain that?

Edited February 25, 20178 yr by Moreno