Hierarchical porous N-doped functionalized reduced graphene oxide by 2-aminoanthraquinone for aqueous zinc-ion hybrid capacitors with high energy density and ultralong-life

Designing and synthesizing organic-based composite electrode with the advantages of abundant resources, low-cost, light-weight, and high performance is one of the key factors for renewable energy storage with intermittent and unstable features, and still has far-reaching significance and challenge. Herein, we successfully synthesized nanostructured hierarchical porous N-doped functionalized reduced graphene oxide by 2-aminoanthraquinone (N-RGO/AAQs) composites via a facile solvothermal method. Introducing N-doping and AAQ organic molecules not only provide more capacity and better wettability, but also help to reduce the agglomeration of RGO nanosheets and obtain more abundant exposed electroactive sites. Coupled with the good conductivity of RGO and the constructed network channels that facilitate the rapid diffusion and transport of ions/electrons, the obtained novel N-RGO/AAQs composite electrodes exhibit excellent electrochemical performance. The aqueous zinc-ion hybrid capacitor assembled with N-RGO/AAQ cathode and metal Zn anode also delivers a high specific capacity of 142.9 mAh g−1 at 0.6 A g−1, an enhanced energy density of 122.9 Wh kg−1 and an ultra-long cycling life of 93.3 % capacity retention after 12,000 cycles. This novel nanostructured organic-based functionalized RGO composite as the cathode is a promising alternative for sustainable high-performance energy storage devices with low-cost, high-safety, light-weight and high-flexibility.