Concisely Modularized Assembling of Graphene-Based Thin Films with Promising Electrode Performance
Assembling and scaling up two dimensional (2D) nanomaterials into macroscopic films represents an accessible fabrication and manipulation technique toward functional materials with promising mechanical and electrical characteristics, extremely desirable for high-performance portable and wearable electronic devices. However, the inter-layer restacking seriously interrupts mass transport to the inner surfaces, strongly impeding the fully releasing of the merits of 2D nanomaterials in bulk phase. In this work, we report a concisely assembling strategy approach to form the thin films with well controlled micron thickness through the layer-by-layer vertical alignment of reduced graphene oxide (RGO) and cellulose nanofiber (CNF) in an aqueous solution. The van der Waals interactions between the nonpolar RGO surface and sugar unit-based backbone of CNF dominantly led to the formation of the extremely compact heterostructures comprising one-dimensional (1D) and two-dimensional (2D) nanocomponents. We found that the heterostructure of CNF/RGO is a ideal method to prepare a flexible and compated film, meanwhile it lead to abundant mesoporous structure and realively high specific surface (up to 100 m2 g-1), good tensile strengthen (250 Mpa), excellent conductivity (120 S cm-1) and high density (1.6 g-1 cm-3). Using such kinds of thin films as electrodes and ionic liquid as electrolyte without any additives, the fabricated symmetric supercapacitors deliveried the high-volumetric double-layer capacitances of up to 120 F cm-3 with the volumetric energy density of 180 Wh L-1, among the highest values for the reported graphene or carbon-based devices. Such excellent electrode performance clearly manifests the electrolyte transport within the compact textures of these thin films, indicative of the presence of substantial polar channels, associated with the orientated alignments of the functional groups on the surface of CNF. Furthermore, these thin films enable being stacked vertically in Lego-like fashion to form multi-layer electrodes, delivering the increased total output power approximately in proportion to the layer.
- This article is part of the themed collection: Graphene-based architectures for energy storage