3D flower-structured graphene from CO2 for supercapacitors with ultrahigh areal capacitance at high current density

Abstract

The widespread application of supercapacitors, which store electrical charge on high-surface-area conducting materials, is limited by their small accessible area and low areal mass loading of active materials due to their microporous structures. Herein, we report that 3D cauliflower-fungus-like graphene (CFG) with hierarchical mesoporous-structure and large fully accessible surface area, which was synthesized directly from CO₂via the one-step exothermic approach, exhibited an ultrahigh areal capacitance up to 1.16 F cm⁻² at a high current density up to 10 A g⁻¹. The excellent performance remained almost unchanged with increasing temperature to 55 °C. Furthermore, the 3D CFG electrode can reach a high efficient-mass-loading of 11.16 mg cm⁻², which meets the current commercial requirement (about 10 mg cm⁻²). This solves a critical issue that the enhancement of mass loading usually sacrifices the mass capacitance.