Synthesis of Joint-Welded Carbon Nanotube Foam @ Ni(OH)₂ Nanosheet-Based Core–Shell 3D Architecture for Freestanding Flexible Electrode for Supercapacitor Applications

Freestanding electrode 3D architectures, based on Ni(OH)₂ nanosheets grown on a joint-welded carbon nanotube foam network, are introduced via a unique and facile chemical bath synthesis strategy. As a result of the unique 3D core configuration of nanotubes and the nanostructural shell design of Ni(OH)₂ nanosheets, the prepared electrode displays an excellent electrochemical performance. The electrode shows an outstanding specific capacitance of 1272 F g⁻¹ at a scan rate of 2 A g⁻¹, and it even retained a value of 517 F g⁻¹ at a scan rate of 20 A g⁻¹. The excellent electrochemical performance is due to the highly conductive nanotube network and the unique nanostructure of Ni(OH)₂ nanosheets, which promote the ion transport in fast speed, while facilitate the charge storage via redox reactions in nanosheets. The large specific capacitance and superior rate performance of core–shell Ni nanosheets, combined with the elasticity of the welded-nanotube network, render these 3D architectures as promising candidates of freestanding electrodes for high-performance flexible supercapacitor applications.