Ternary graphene-carbon nanofibers-carbon nanotubes structure for hybrid supercapacitor

Carbon materials with hierarchical nanostructures are well accepted propitious materials for electrode application in supercapacitor devices. Herein, a hierarchical ternary carbon aerogel structure is designed by integrating graphene (Gr), carbon nanofibers (CNFs), and carbon nanotubes (CNTs). The as-synthesized CNTs@Gr-CNF materials are characterized by different analytical techniques for the electrode application in a supercapacitor. In the three-electrode system, CNTs@Gr-CNF electrode material exhibits an enhanced electrochemical performance in which a high specific capacitance of 521.5 F g⁻¹ was obtained at 0.25 A g⁻¹ along with the excellent capacitance retention of 98% after consecutive 10,000 charge-discharge cycles at 5 A g⁻¹ in 6 M KOH. In addition, a hybrid supercapacitor device based on CNTs@Gr-CNF as the negative electrode and NiCo₂S₄ nanoneedle grown on nickel foam as the positive electrode was fabricated. The hybrid device shows 218 F g⁻¹ of specific capacitance at 1 A g⁻¹ and an energy density of 62.13 Wh Kg⁻¹ at a power density of 789.66 W kg⁻¹. Moreover, the device exhibits an excellent cyclic stability with the retention of 91.7% of its specific capacitance after 10,000 charge-discharge cycles. The obtained results signify that the CNTs@Gr-CNF material possesses highly desirable properties for negative electrode application in advanced hybrid supercapacitor.