Flexible, highly conductive, and free-standing reduced graphene oxide/polypyrrole/cellulose hybrid papers for supercapacitor electrodes

Abstract

We report a facile scale-up process to fabricate a novel type of hybrid paper electrode composed of reduced graphene oxide (RGO), polypyrrole (PPy) and cellulose. Through the optimization of preparation parameters (including the processes of in situ polymerization of pyrrole and chemical reduction of graphene oxide by using NaBH₄), the fabricated hybrid paper had an extremely low sheet resistance of 1.7 Ω sq⁻¹. Also, the hybrid paper possessed favorable mechanical flexibility and outstanding conductance stability. When the paper was evaluated as a free-standing and binder-free supercapacitor electrode, the unique construction (i.e., the cellulose fiber frame supporting interpenetrated RGO–PPy nanoacrhitectures) endowed it with high electrochemical activity, such as high areal capacitance of 1.20 F cm⁻² at 2 mA cm⁻² and good cycling stability with a capacitance retention of 89.5% after cycling 5000 times, which was tested in a three-electrode configuration. In addition, an all-solid-state laminated symmetric supercapacitor was prepared by assembling two pieces of hybrid paper electrodes and using a H₃PO₄/PVA gel as the electrolyte. The solid-state supercapacitor had a high areal capacitance of 0.51 F cm⁻² at 0.1 mA cm⁻² and a high energy density of 1.18 mW h cm⁻³. These results suggest that the hybrid paper is a promising electrode material and may be useful for the development of flexible high-performance and hand-held energy storage devices. More importantly, this work provides a good reference for the fabrication of other types of hybrid paper electrodes.