Rational design of sandwiched polyaniline nanotube/layered graphene/polyaniline nanotube papers for high-volumetric supercapacitors

The adjustment and optimization of graphene-based electrode structures are crucial to achieve both high volumetric and gravimetric capacitances for portable energy storage devices. Structures of reduced graphene oxide (RGO)-polyaniline (PANI) nanotube hybrid electrodes were facilely regulated and rationally designed by in-situ MnO2 nanowire-templated polymerization. Typically, two different architectures of RGO-PANI composites were obtained by controlling the content of MnO2 nanowires in graphene papers. The assembled symmetric device based on the porous RGO-PANI nanotube papers (0.18 mg cm(-2), 20.0 mu m), showed a high gravimetric specific capacitance of 956 F g(-1) (against the mass of single electrode) at 1 A g(-1) with excellent rate capability of 74.3% from 1 A g(-1) to 10 A g(-1). In addition, another symmetric device based on the sandwiched polyaniline nanotubeilayered graphene/polyaniline nanotube papers (0.80 mg cm(-2), 4.02 mu m), provided an ultrahigh volumetric capacitance (722 F cm(-3) at 2 A cm(-3)) and a decent gravimetric capacitance (363 F g(-1) at 1 A g(-1)) calculated against the volume and mass of single electrode. With these excellent volumetric and gravimetric capacitive performances, this polyaniline nanotube/layered graphene/polyaniline nanotube supercapacitor holds the potential for high-volumetric and gravimetric-performance energy storages. (C) 2016 Elsevier B.V. All rights reserved.