Limits to the magnitude of capacitance in carbon nanotube array electrode based electrochemical capacitors

摘要

Nanostructured electrochemical capacitors (ECs) are advantageous for charge and energy storage due to their intrinsically large surface area, which contributes to a large electrostatic/double layer capacitor (C_(dl)). However, the intrinsically small density of states in nanostructures results in a quantum capacitor (C_Q) in series with C_(dl) which could diminish the total device capacitance value (C(tot)). We investigate, through comparison with experiment, the relative magnitudes of C_(dl) and C_Q in electrodes constituted of carbon nanotube arrays. Consequently, we attribute the increase in C_(tot) resulting from ionizing radiation to an increase in C_o and suggest limits to the capacitance in ECs.