Flexible graphene/carbon nanotube hybrid papers chemical-reduction-tailored by gallic acid for high-performance electrochemical capacitive energy storages

Abstract

Mechanically robust graphene papers with both high gravimetric and volumetric capacitances are desired for high-performance energy storages. However, it’s still a challenge to tailor the structure of graphene papers in order to meet this requirement. In this work, a kind of chemical-reduction-tailored mechanically-robust reduced graphene oxide/carbon nanotube hybrid paper has been reported for high-performance electrochemical capacitive energy storages. Gallic acid (GA), as an excellent reducing agent, was used to reduce graphene oxide. Through vacuum filtration of gallic acid reduced graphene oxide (GA-rGO) and carboxylic multiwalled carbon nanotubes (MWCNTs) aqueous suspensions, mechanically robust GA-rGO/MWCNTs hybrid papers were obtained. The resultant hybrid papers showed high gravimetric capacitance of 337.6 F g−1 (0.5 A g−1) and volumetric capacitance of 151.2 F cm−3 (0.25 A cm−3). In addition, the assembled symmetric device based on the hybrid papers exhibited high gravimetric capacitance of 291.6 F g−1 (0.5 A g−1) and volumetric capacitance of 136.6 F cm−3 (0.25 A cm−3). Meanwhile, it exhibited excellent rate capability and cycling stability. Above all, this chemical reduction tailoring technique and the resultant high-performance GA-rGO/MWCNTs hybrid papers give an insight for designing high-performance electrodes and hold a great potential in the field of energy storages.