Hierarchical CoNi ₂ S ₄ nanosheet/nanotube array structure on carbon fiber cloth for high-performance hybrid supercapacitors

Well-defined nanostructures are attractive due to their excellent advantages in enhancing the performance of electrochemical energy storage. In this work, a kind of hybrid structure of hierarchical CoNi ₂ S ₄ nanosheet/nanotube array directly assembled on carbon fiber cloth has been designed and developed for high-performance supercapacitors. CoNi ₂ S ₄ nanosheet/nanotube arrays are fabricated through orderly electrodeposition of ZnO nanorod arrays and CoNi ₂ S ₄ nanosheets, followed by removing ZnO nanorods template. Benefiting from the unique hollow nanostructure with abundant electrochemical active sites, the specific capacitance of this electrode can reach up to 995.8 C g ⁻¹ at a current density of 2 A g ⁻¹ , along with excellent rate capability (740 C g ⁻¹ at 50 A g ⁻¹ ). Moreover, the hybrid supercapacitors are prepared by using hierarchical CoNi ₂ S ₄ nanosheet/nanotube arrays as positive electrode and reduced graphene oxide-carbon nanotubes as negative electrode for energy storage application, which demonstrate a high energy density of 35 Wh kg ⁻¹ at a power density of 3 kW kg ⁻¹ and excellent cycle stability with 96.9% capacitance retention after 10000 cycles. This work provides a feasible and a practical approach to fabricate CoNi ₂ S ₄ hollow nanostructures and its huge potential in energy storage.