High performance of a solid-state flexible asymmetric supercapacitor based on graphene films

Abstract

Solid-state flexible energy storage devices hold the key to realizing portable and flexible electronic devices. Achieving fully flexible energy storage devices requires that all of the essential components (i.e., electrodes, separator, and electrolyte) with specific electrochemical and interfacial properties are integrated into a single solid-state and mechanically flexible unit. In this study, we describe the fabrication of solid-state flexible asymmetric supercapacitors based on an ionic liquid functionalized-chemically modified graphene (IL-CMG) film (as the negative electrode) and a hydrous RuO(2)-IL-CMG composite film (as the positive electrode), separated with polyvinyl alcohol-H(2)SO(4) electrolyte. The highly ordered macroscopic layer structures of these films arising through direct flow self-assembly make them simultaneously excellent electrical conductors and mechanical supports, allowing them to serve as flexible electrodes and current collectors in supercapacitor devices. Our asymmetric supercapacitors have been optimized with a maximum cell voltage up to 1.8 V and deliver a high energy density (19.7 W h kg(-1)) and power density (6.8 kW g(-1)), higher than those of symmetric supercapacitors based on IL-CMG films. They can operate even under an extremely high rate of 10 A g(-1) with 79.4% retention of specific capacitance. Their superior flexibility and cycling stability are evident in their good performance stability over 2000 cycles under harsh mechanical conditions including twisted and bent states. These solid-state flexible asymmetric supercapacitors with their simple cell configuration could offer new design and fabrication opportunities for flexible energy storage devices that can combine high energy and power densities, high rate capability, and long-term cycling stability.

All-solid-state electrochemical capacitors using MnO2/carbon nanotube composite electrode

“…Electrochemical capacitors (ECs) are one of the most promising energy storage devices because of their high power density, fast charge-discharge, and good cycle performance [1][2][3]. In recent years, transition metal oxides which store energy by utilizing the pseudocapacitance arising from fast and reversible faradic reactions in the electrode surface are good fundamental candidates for ECs [4][5][6].…”

Asymmetric supercapacitor based on VS2 nanosheets and activated carbon materials

“…[16][17][18] . Activated carbon (AC) is the most suitable negative electrode material adopted for hybrid capacitors due to the numerous merits listed above but also due to its facile preparation process 19,20 .…”

Carbon Nanomaterials for Flexible Energy Storage

“…More remarkably, such devices can be operated with high rate of 10 A/g with 79.4% retention of specific capacitance. [106] 4. Conclusion and Future Directions The significant reliance on electrical energy for the progression of society has attracted tremendous research efforts on developing advanced energy storage systems.…”