Free-standing three-dimensional graphene and polyaniline nanowire arrays hybrid foams for high-performance flexible and lightweight supercapacitors

Free-standing three-dimensional hierarchical porous reduced graphene oxide foam (RGO-F) was first fabricated by a "dipping and dry" method using nickel foam as a template. Three-dimensional (3D) RGO-F with high conductivity provides large porosity compared to conventional graphene films. Polyaniline (PANI) nanowire arrays aligned on the foam (RGO-F/PANI) were synthesized by in situ polymerization. A symmetric supercapacitor with high energy and power densities was fabricated using a RGO-F/PANI electrode. The highly flexible RGO-F/PANI foam can directly serve as an electrode with no binders or conductive additives. Owing to the well-ordered porous structure and high electrochemical performance of the RGO-F/PANI composite, the symmetric device exhibits high specific capacitance (790 F g(-1)) and volumetric capacitance (205.4 F cm(-3)), and it shows a maximum energy density and power density of 17.6 W h kg(-1) and 98 kW kg(-1). Moreover, the device possesses an excellent cycle life with 80% capacitance retention after 5000 cycles.