Ultrahigh-rate supercapacitors based on eletrochemically reduced graphene oxide for ac line-filtering

Abstract

The recent boom in multifunction portable electronic equipments requires the development of compact and miniaturized electronic circuits with high efficiencies, low costs and long lasting time. For the operation of most line-powered electronics, alternating current (ac) line-filters are used to attenuate the leftover ac ripples on direct current (dc) voltage busses. Today, aluminum electrolytic capacitors (AECs) are widely applied for this purpose. However, they are usually the largest components in electronic circuits. Replacing AECs by more compact capacitors will have an immense impact on future electronic devices. Here, we report a double-layer capacitor based on three-dimensional (3D) interpenetrating graphene electrodes fabricated by electrochemical reduction of graphene oxide (ErGO-DLC). At 120-hertz, the ErGO-DLC exhibited a phase angle of −84 degrees, a specific capacitance of 283 microfaradays per centimeter square and a resistor-capacitor (RC) time constant of 1.35 milliseconds, making it capable of replacing AECs for the application of 120-hertz filtering.

Scalable fabrication of high-power graphene micro-supercapacitors for flexible and on-chip energy storage

“…With its high theoretical surface area (2630 m 2 g À 1 ) and electrical conductivity, graphene could produce supercapacitors with ultrahigh power. We 11 and others [13][14][15] have developed thin-film graphene supercapacitors that demonstrated high-power performance with superior frequency response. Although promising, the sandwich structure of these supercapacitors limits their integration into electronic circuits.…”

Graphene/polymer composites for energy applications

“…7,80,90,[133][134][135] However, CP electrodes exhibit large volume changes during the doping/ dedoping processes, so the electrodes degrade and the electrochemical performance diminishes during cycling tests. 130 Adding graphene to the polymers can improve the mechanical and electrochemical cycling stability of CP electrodes.…”

“…Therefore, the performances of EDLCs strongly depend on their architecture and the specific surface areas of their electrodes. 130 A pseudo-capacitor works predominately through fast reversible redox reactions. 132 Compared with EDLCs, pseudo-capacitors have much larger specific capacitances, but usually possess lower charge/discharge rates and worse cycling stability.…”

“…129,130 A high-performance supercapacitor should have high energy density (1-10 W h kg À1 , determined by its capacitance and voltage), power density (103-105 W kg À1 , determined by its voltage and internal resistance), and ultra-long cycling life (>100,000 cycles). 131 Thus, supercapacitors act as a perfect complement for batteries or fuel cells, and used in cooperation they are considered to be promising power supplies for versatile applications such as environmentally friendly automobiles, artificial organs, and high-performance portable electronics.…”

Morphological characterization and impedance spectroscopy study of porous 3D carbons based on graphene foam-PVA/phenol-formaldehyde resin composite as an electrode material for supercapacitors

“…However, at this frequency EDLCs are not capable of this; rather they behave like a transmission line, acting like resistors instead of capacitors. 11 This is usually ascribed to unsuitable pore structure and distribution, leading to a high rate of diffusion and charge transfer.…”