A rapid heat pressing strategy to prepare fluffy reduced graphene oxide films with meso/macropores for high-performance supercapacitors

Among the various graphene-based macroscopic architectures, paper-like graphene films exhibit outstanding superiority such as high power output, good malleability and scale-up production. However, the two dimensional graphene nanosheets can easily restack to form dense lamellar microstructures especially in paper-like film, which lose most of the accessible surface and fade the performance of films. In this study, a simple yet high efficient heat pressing method is successfully developed to prepare reduced graphene oxide (RGO) nanosheets with crumpled topography, which can weaken the p-p and van der Waals interactions between nanosheets and inhibit the restacking of nanosheets. Therefore, the resultant RGO film exhibits fluffy layered and meso/ macroporous structure (this RGO film is named as f-RGOF). Additionally, the chemical reduction combined with iodine doping reaction endow f-RGOFs with high conductivity of 3000-3300 Sm-1. Electrochemical studies demonstrate that the f-RGOF exhibits a high gravimetric capacitance (CM) of 238.4 F g(-1) at current density of 0.5 A g(-1), and similar to 67% retention (158.8 F g(-1)) with a small IR drop (0.16 V) even up to 80 A g(-1). Moreover, the electrochemical performance of f-RGOFs only shows a slight decay (85% CM retention and almost no decay for rate capability) with the increase of areal mass loading, indicating the high utilization rate of electrode material. For practical applications, the flexible solid-state supercapacitors (FSSCs) based on f-RGOFs are also fabricated, which exhibit comparable volumetric energy density of 1.7mWh cm(-3) to 4 V/500 mu A h Li thin-film batteries as well as excellent mechanical flexibility. These results demonstrate that the strategy can be potentially applied for fabricating restacking-inhibited and high-performance RGO films using in flexible electronic devices.