Moreno Posted June 14, 2016 Posted June 14, 2016 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?
Enthalpy Posted June 17, 2016 Posted June 17, 2016 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".
Moreno Posted February 25, 2017 Author Posted February 25, 2017 (edited) 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, 2017 by Moreno
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