Charge Transfer Between Polyaniline and Carbon Nanotubes Supercapacitors: Improving Both Energy and Power Densities

Abstract

The charge transfer properties of a novel asymmetric device configuration combining polyaniline ͑PANI͒ as the battery component and single-wall carbon nanotubes ͑SWNTs͒ as the supercapacitor component were investigated. The scan rate in cyclic voltammetry is an important factor modulating the relative weight of the fast double layer/pseudocapacitance and slow electrochemical capacitance and changing the total charge and energy density output. At a scan rate of 1 mV/s, the energy density of the PANI_SWNTs device is six times higher than that of the bare SWNTs device. At different voltage ranges of galvanostatic discharge, the PANI_SWNTs device exhibits three different discharge behaviors. The SWNT-like discharge dominates the initial stage. The PANI electrochemical reaction dominates the middle stage of the discharge, which coincides with the PANI's conductive state. Once the charge from the PANI electrochemical reaction is used up, the remaining charge in SWNTs sustains the discharge in the final stage. A suspension period was therefore introduced to the middle stage of PANI_SWNTs device discharge, which resulted in a 10% increase of the power density. The understanding of the interaction between the fast double layer/ pseudocapacitance and slow electrochemical capacitance benefits for designing the architecture of supercapacitor-battery satisfying energy and power requirements of practical applications.

A “skeleton/skin” strategy for preparing ultrathin free-standing single-walled carbon nanotube/polyaniline films for high performance supercapacitor electrodes

“…3,23 Much effort has gone into improving the energy density of SWCNT-based electrodes, such as adding conducting polymers into SWCNTbased electrodes. 17,[24][25][26][27][28][29][30][31][32][33][34] The SWCNT/conducting polymer electrodes display high energy density due to pseudocapacitance originating from the conducting polymer, but, their power density is dramatically reduced in comparison to the pure SWCNT-based electrodes, due to the poor electrical conductivity of conducting polymers. Therefore, one of the most critical aspects in the development of SWCNT/conducting polymer supercapacitors is to optimize the energy density without deteriorating their high power capability, as these two parameters determine the ultimate performance of the supercapacitors.…”

Recent Advances in Continuum Modeling of Interfacial and Transport Phenomena in Electric Double Layer Capacitors

“…This hump is typical of experimental CV curves. 1,205,[207][208][209] Different interpretations have been proposed in the literature to explain this hump including (i) electrolyte starvation due to limited amount of ions at low concentrations, 158,210 (ii) redox reactions at the electrode surface, 1,[207][208][209][211][212][213][214][215][216][217] (iii) different ion mobilities between anions and cations, 215 and (iv) saturation of ions at the electrode surface. 205,206 However, there was no clear evidence and definitive explanation to the commonly observed hump in the CV curves.…”

A Transformerless Medium Voltage Multiphase Motor Drive System

“…The cascaded H-bridges with the line inductor works as an active pulse-width modulation (PWM) rectifier. The cascaded H-bridge structure (known as cascaded multilevel converter) has attractive advantages in applications of the high-power MV and high-voltage (HV) drives with frequency modulation control [20]. In the proposed scheme, the cascaded multilevel converter technique makes semiconductor devices with voltage and current limitation can be used in the converter or inverter which is directly connected to the MV power grid without any isolation transformer.…”