Supramolecular Assembly of 1D Pristine Carbon Nanotubes and 2D Graphene Oxides into Macroscopic All‐Carbon Hybrid Sponges for High‐Energy‐Density Supercapacitors

Abstract The rational design and targeted synthesis of macroscopic and ultralight all‐carbon sponges with satisfying electron/proton conductivity through a simple and environmentally friendly approach is challenging. Herein, three‐dimensional carbon nanotube‐graphene oxide (CNT‐GO) hybrid hydrogels have been constructed by the gelation of an aqueous dispersion of graphene oxide (GO) induced by pristine carbon nanotubes (CNTs) without any additives or other crosslinkers. Upon reduction of CNT‐GO hydrogels and removal of water by freeze‐drying, the resulting carbon nanotube‐graphene (CNT‐G) aerogels exhibit a unique all‐carbon continuous framework with a hierarchical porosity that allows high‐rate transport of electrolyte ions and electrons throughout the electrode matrix. As a result, they show high specific energy (31.3 Wh kg⁻¹), high specific capacitance with excellent rate performance (≈71 % retention at 10 A g⁻¹) and cycling stability (≈100 % retention at 10 A g⁻¹ for 5000 cycles) in two electrode systems, and thus great potential as promising electrode materials for next‐generation supercapacitors.