Flexible, Free‐Standing and Holey Graphene Paper for High‐Power Supercapacitors

Abstract

Flexible supercapacitors based on bendable electrodes have aroused much interest for integration in clothing materials and portable electronic devices.However, simultaneous achievement of high areal energy and high power densities still presents a great challenge. Herein we report the fabrication of

Free-standing hybrid films based on graphene and porous carbon particles for flexible supercapacitors

“…We recently reported a simple way of fabricating free-standing and flexible graphene papers (GP). 34 In that study, we proved that the supercapacitors built up with this type of electrodes exhibit an excellent stability and high areal power (up to 280 mW cm -2 ) and energy (up to 60 µWh cm -2 ). In the present work we have taken a step forward and investigated the fabrication of hybrid papers made up of graphene units and highly porous carbon particles.…”

“…35 A typical graphene paper obtained from these graphene units has a layered structure (see Figure S1d), with a thickness of 30 µm, a volumetric density of 0.8 g cm -3 and a specific surface area (measured by methylene blue) of 700 m 2 g -1 . 34 The carbon nanosheets (CK) used in the experiments were obtained by direct carbonization of potassium citrate as reported by Sevilla and Fuertes,32 whereas the carbon microspheres (CS) were synthesized by the chemical activation of glucose hydrochar with a mixture of potassium bicarbonate and melamine. 33 SEM and TEM inspections of the morphology of these particles reveals that the carbon nanosheets consist of thin layers that are fully interconnected and the carbon microspheres consist of spherical particles with a diameter of 250 ± 40 nm (see Figure S2).…”

Capacitive Properties of the Binder‐Free Electrode Prepared from Carbon Derived from Cotton and Reduced Graphene Oxide

“…The reason for the poor rate capability and larger iR drops of the all-solid-state ECs could be that the transport of ions in gel electrolyte is slower than in liquid electrolyte. [51] Besides, the CV curves of the device under different bending states have been recorded and shown in Figure 8a. It is clear that the areas surrounded by the CV curves at different bending angles have nearly invariable shapes, and the current responses have only slight decrease compared with the normal state, which indicate the fairly good flexibility of the cells.…”

Multiscale porous graphene oxide network with high packing density for asymmetric supercapacitors

“…The vacuum filtration process is reported to be suitable for assembling GO nanosheets into paper-like electrodes with high flexibility and good electrical conductivity. 24,25 However, the GO nanosheets tend to stack into graphite during vacuum filtration, which results in significant loss of surface area. The incorporation of spacer materials (metal oxide nanomaterials, 26 polystyrene nanospheres, 27,28 polymethyl methacrylate spheres, 29 etc.)…”

“…Additionally, the value is also larger than or comparable to that of the previously reported graphene or GO paper electrodes at the same current density. 25,40,41 The micropores and mesopores of the MPGP provide amounts of active sites for charge accumulation, which further boost the specific capacitance of the MPGP. Figure 6(b) shows the GCD curves of the MPGP collected at current densities ranging from 1 to 16 A/g.…”