3D flower-like nickel cobalt sulfide directly decorated grassy nickel sulfide and encapsulated iron in carbon sphere hosts as hybrid energy storage device

Developing high-performance supercapacitors is of great significance in the area of renewable energies by virtue of having both high energy and power densities. In this work, an innovative strategy is employed for the fabrication of binder-free binary nickel-cobalt-sulfide (NCS) nanosheets (NSs) directly decorated onto the hydrothermal nickel-sulfide (Ni3S2) nanowires (NWs) as the positive electrodes. The NCS/Ni3S2-nickel foam (NF) positive electrodes rendered superior specific capacity of 499.1 mAh.g 1 at 6 A.g 1. Encapsulated iron into the carbon sphere hosts (Fe-HTCSs) are used as the negative counterparts, exhibiting remarkable specific capacitance of 336.6 F.g 1 (at 0.1 A.g 1). The prepared positive and negative electrodes are on the merit of developing advanced asymmetric supercapacitors (ASCs) by virtue of encouraging electrochemical results. The fabricated NCS/Ni3S2-NF//Fe-HTCS ASCs not only possess a wide operating potential window (1.7 V), but also receive benefits from high energy (46.2 Wh.kg 1) and power densities (2.0 kW.kg 1), which secure the applicability of the assembled ASC devices in high-performance electronics and renewable energy systems.