Growth of β-Co(OH)_2 Nanoflowers on Carbon Nanotube Papers and Its Electrochemical Capacitance Performance

Uniform hierarchical flower-like β-Co(OH)2 anchored on conducting carbon nanotube(CNT) papers were successfully synthesized by hydrothermal method, which could be served as flexible electrode material for high-performance electrochemical capacitors. The structure, morphology and properties of the products were studied by X-ray diffraction(XRD) and scanning electron microscope(SEM). The results indicated that the as-prepared material was pure brucite phase. Three dimensional(3D) loose nano-flowerlike structure with the diameter of about 3 μm were stacked by multilevel β-Co(OH)2 flakes. Electrochemical performances of this flexible paper-like electrode were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy test in 6 mol/L KOH aqueous electrolyte. Electrochemical data indicated that the interesting β-Co(OH)2/CNT paper composite delivered a considerable specific capacitance of 2764 F/g at current density of 2 A/g. The CNT paper acted as a good conductive and flexible substrate for the composite electrodes in supercapacitors, and the hierarchical flower-like structure of the β-Co(OH)2 could facilitate the contact of the electrolyte. The β-Co(OH)2 nanoflower composite performed an obvious improvement of rate capacity and cycling stability, compared with pure phase β-Co(OH)2.