3D hierarchical carbons composed of cross-linked porous carbon nanosheets for supercapacitors

Abstract

3D hierarchical porous carbons with good electric conductivity and excellent physicochemical stability are of great potential as electrode materials for supercapacitors. Herein, we report a directing-confinement-template strategy for synthesis of 3D hierarchical carbons composed of cross-linked porous carbon nanosheets from fluorene molecules. The 3D cross-linked networks serve as highways for electron conduction while the multi-level pore structures function as channels for fast ion transport with abundant active sites for ion adsorption. Benefiting from the above merits, the hierarchical carbons manifest a high gravimetric capacitance of 344 F g−1 at 0.05 A g−1, a superb rate capability with the capacitance up to 278 F g−1 even at 100 A g−1 and an outstanding cycle stability with only 0.7% decay after 50,000 cycles in alkaline electrolyte. Remarkably, hierarchical carbon-based capacitor displays a high energy density of 31.9 Wh kg−1 in 3 M ZnSO4 neutral electrolyte owing to the wide voltage window of 2.2 V. This work opens up a new avenue for designing hierarchical carbons via directing and confinement template approach from small aromatic molecules for high-performance energy storage devices.