Large scale α-Co(OH)2 needle arrays grown on carbon nanotube foams as free standing electrodes for supercapacitors

We have successfully fabricated 3D carbon nanotube foams macrostructure by direct conversing CO2. Taking these carbon nanotube foams as substrates, large scale mace-like carbon nanotube foams/Co(OH)2 ordered arrays have been fabricated by a simple hydrothermal method. Electrochemical analysis indicates that the carbon nanotube foams hybrid architectures exhibit good energy-storage performance with high specific capacity of 614.3C g−1 at 0.5 A g−1 and 444.5C g−1 at 10 A g−1 calculated based on active materials with a voltage window of 0.45 V. Besides, the electrodes also illustrate excellent long cycle life along with 96.8% specific capacity retained after 3000 cycle tests. An asymmetric supercapacitor was also assembled using carbon nanotube foams/Co(OH)2 as positive electrode and bare carbon nanotube foams as negative electrode. The highest power density and energy density of the asymmetric cell is 7.2 kW kg−1 and 13.0 Wh kg−1, respectively. Moreover, this environmental friendly template-directed CVD technique is adaptable and multitalented, and can be a general strategy for preparing a kind of three-dimensional macroscopic structures with excellent properties and novel applications.