Binder-free supercapacitive of ultrathin Co(OH)₂ nanosheets-decorated nitrogen-doped carbon nanotubes core-shell nanostructures

Abstract

Three-dimensional (3D) nitrogen-doped carbon nanotubes (N-CNTs)/Co(OH)₂ core-shell nanostructures as binder-free supercapacitor electrode have been synthesized via electrodeposition and chemical vapour deposition. The ultrathin Co(OH)₂ nanosheets are uniformly coated on the surface of N-CNTs. Such unique well-designed binder-free electrode exhibits a high areal capacitance (0.46 F cm⁻² at a current density of 1 mA cm⁻²) and good cycling stability (81.2% capacitance retention after 2000 cycles). In the electrode, the cable-like N-CNTs around Ni foam with close contact act as current collector, facilitating the electrical transport, while two-dimensional Co(OH)₂ nanosheets grown on external surface increase the surface area and provide good contact with ions at electrode/electrolyte interface, exhibiting low charge transfer resistance (Rct) and better charge storage performance. As a result, such combined synthetic strategy may provide design guidelines for constructing advanced binder-free supercapacitors electrode.

Keywords:

• Co(OH)₂
• Nitrogen-doped CNTs
• Core-shell nanostructures
• Binder-free electrodes
• Electrodeposition

Acknowledgment

The authors also thank Electron Microscopy Center of Chongqing University for materials characterizations.