Fabrication of Rambutan-like Activated Carbon Sphere/Carbon Nanotubes and Their Application as Supercapacitors

Developing advanced electrochemical double-layer supercapacitors (EDLCs) with high energy density and capacitance can be realized by exploring the electrodes possessing large specific surface area and high electronic conductivity. Here, we fabricated rambutan-like activated carbon sphere/carbon nanotube (ACS/CNT) composites which can be used as electrode materials in EDLCs. Curved CNTs have a polycrystalline structure with tens of nanometers in diameter and hundreds of nanometers in length and are uniformly grown on the surface of the ACS. The unique three-dimensional (3D) microstructure contributes to the ideal electrochemical performance of composite electrodes by combining high specific surface area and superior electrical conductivity. The specific capacitance of the ACS/CNT composite is 180 F/g, which is over threefold that of the pristine ACS electrode at a current density of 2.5 A/g. ACS/CNT electrodes exhibit an excellent cyclical ability at 10 mV/s sweep rate in the working voltage range, and the capacitance retention is almost 80% after 1000 cycles. The preparation of 3D microstructure opens up a new way of designing electrodes with a 3D conductive network and lays the foundation for the development of lightweight energy storage supercapacitors.

Automated summary

By fabricating rambutan-like activated carbon sphere/carbon nanotube (ACS/CNT) composites as electrode materials with a unique three-dimensional microstructure, high specific capacitance and excellent cyclic performance have been achieved. The growth of curved carbon nanotubes on the surface of activated carbon spheres contributes to superior electrical conductivity and specific surface area in the composite electrodes.