Preparation and electrochemical properties of Ni(OH)₂-carbon nanotubes-reduced graphene oxide composites

Ni(OH)₂-carbon nanotubes-reduced graphene oxide (Ni(OH)₂-CNTs-RGO) ternary composites were synthesized by simple and practicable one-pot hydrothermal synthesis method. The influence of different reaction temperatures on properties of composite materials was researched. The microstructure and morphology of Ni(OH)₂-CNTs-RGO composites were characterized by XRD, FTIR, Raman spectroscopy, X-ray photoelectron spectroscopy(XPS), SEM and TEM. The electrochemical characteristics of Ni(OH)₂-CNTs-RGO electrode composites were tested by cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and galvanostatic charge/discharge. The results show that the prepared Ni(OH)₂-CNTs-RGO composite has large specific surface area and 3D network structure when the reaction temperature is 120℃. The synthesized Ni(OH)₂-CNTs-RGO composite shows that hexagonal β-Ni(OH)₂ nano sheets and CNTs are homogeneously dispersed and inserted into RGO sheets. The Ni(OH)₂-CNTs-RGO electrode composite exhibits the discharge specific capacity up to 362.8 mAh/g at 0.2 C and 286.2 mAh/g at 5 C, which is still higher than the specific capacity of Ni(OH)₂. The CNTs and RGO collaborative role effectively improves the conductivity of the electrode material and the utilization of active material. Finally, the rate performance of Ni(OH)₂-CNTs-RGO composite is improved.