Flexible Pillared Graphene‐Paper Electrodes for High‐Performance Electrochemical Supercapacitors

Abstract

Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s(-1) , the specific capacitance of the pillared GP is 138 F g(-1) and 83.2 F g(-1) with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s (-1) , the specific capacitance can reach 80 F g(-1) in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. The pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage.

A Free-standing Graphene-Polypyrrole Hybrid Paper via Electropolymerization with an Enhanced Areal Capacitance

“…The rGO-PPy60 paper presented a maximum energy density of 61.3 μWh cm -2 at a power density of 1.2 mW cm -2 , while it maintained 49.5 μWh cm -2 at 14.2 mW cm -2 . Our rGO-PPy paper displayed higher energy density compared to the reported results for graphene paper [10], graphenepolypyrrole film [23], graphene-PANI paper [52], or even graphene-MnO 2 electrode [41] especially at high power density.…”

“…Although these graphene-based flexible electrodes present promising gravimetric capacitance, they normally deliver a very low areal capacitance in the range of 57 to 94.5 mF cm -2 due to the low areal mass loading (< 1 mg cm -2 ) [9,10]. For practical usage, it is suggested that the areal mass loading is at least 5 mg cm -2 and the electrode thickness is between 50-200 μm [11,12].…”

Recent advances in flexible supercapacitors based on carbon nanotubes and graphene

“…Graphene films can be prepared through various methods including vacuum filtration [94][95][96], drop-casting [97,98], layer-by-layer assembly [99] and through the compression of graphene aerogel or graphene foam [100,101]. However, the electrochemical performance of graphene films is restricted by the restacking of graphene sheets, because agglomeration decreases the specific surface area and results in more difficult diffusion of the electrolyte ions.…”

Flexible free-standing graphene paper with interconnected porous structure for energy storage

“…Spacers used include surfactants, polymers, nanoparticles and even water. [15][16][17][18] The approaches used to construct threedimensional porous graphene assembly involve the technique of hydrothermal, 19 template-assisted CVD, organic sol-gel 20,21 and freeze drying.…”