Nickel Cobalt Sulfide core/shell structure on 3D Graphene for supercapacitor application.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Supercapacitors are crucial for energy storage.
• Developing high-performance electrode materials is essential for advancing supercapacitor technology.
• Nickel cobalt sulfides offer promising pseudocapacitive properties.

Purpose of the Study:

• To nano-engineer a 3D core/shell nickel cobalt sulfide structure on graphene for supercapacitor applications.
• To investigate the electrochemical properties and performance of the synthesized composite material.
• To evaluate the potential of this material in asymmetric energy storage devices.

Main Methods:

• Hydrothermal synthesis of a 3D core/shell structure composed of NiCo2S4 nanotubes (NCS) as the core and CoxNi(3-x)S2 nanosheets (CNS) as the shell, supported on CVD-grown graphene.
• Characterization of the material's morphology, structure, and electrochemical performance.
• Fabrication and testing of a prototype asymmetric supercapacitor device using the graphene/NCS/CNS composite as the positive electrode and reduced graphene oxide (RGO) as the negative electrode.

Main Results:

• The graphene/NCS/CNS composite electrode exhibited a high areal capacitance of 15.6 F/cm² at 10 mA/cm².
• The material demonstrated excellent cycling stability (93% after 5000 cycles) and rate capability (74.36% retention from 10 to 100 mA/cm²).
• The asymmetric device achieved a high energy density of 23.9 Wh/kg and a power density of 2460.6 W/kg.

Conclusions:

• The 3D core/shell NCS/CNS structure on graphene significantly enhances electrochemical performance for supercapacitors.
• The synergistic effects of the core-shell structure and graphene support contribute to superior electron and ion transport, and high active surface area.
• This high-performance electrode material holds great promise for future applications in advanced energy storage devices.