Redox-active 7-aminoindole and carbon nanotubes co-modified reduced graphene oxide for Zn-ion hybrid capacitors with excellent energy density and super-long cycling stability

Abstract

With the explosive growth and popularity of portable electronic devices and electric vehicles, as well as the increasing importance of renewable energy, the development of sustainable green energy storage devices with high-performance has been greatly stimulated. Herein, benefiting from the abundant reaction and storage sites brought by redox-active 7-aminoindole (7-Ai) and its role as molecular space can effectively reduce the agglomeration of RGO nanosheets, as well as the network channels constructed by carbon nanotubes (CNTs) are conducive to the rapid diffusion and transport of ions/electrons, the innovatively designed and synthesized novel 7-Ai organic molecules and CNTs co-modified reduced graphene oxide (Ai-RGO/CNTs) nanocomposites exhibit excellent electrochemical properties in symmetric supercapacitor. More surprisingly, the new type of zinc-ion hybrid capacitors (ZHCs) constructed with the optimal Ai-RGO/CNTs-30 electrode as cathode, Zn foil as anode, and non-corrosive 2 M ZnSO4 solution as electrolyte, delivered a satisfactory specific capacity of 183.86 mAh g−1 at 0.5 A g−1, an excellent energy density (163.63 Wh kg−1) and power density (17.8 kW kg−1), and an outstanding super-long cycling stability (87.12%) for 16 000 cycles at 10 A g−1, which has broad application prospects for high-performance zinc-ion storage device.