A novel β-Ni(OH)₂/CNTs nano-composite used in electrochemical hybrid capacitor

A novel β-Ni(OH)₂/carbon nanotubes (CNTs) nano-composite was prepared by hydrothermal synthesis method in this work. The dimension of the β-Ni(OH)₂ grain was controlled between 50~80 nm, as large as the diameter of the CNTs. The mass ratio of the CNTs to Ni(OH)₂ was 1:15. The nano-composite was applied to activated carbon (AC)/NiOOH electrochemical hybrid capacitor and the electrochemical performance of the capacitor was tested. The results showed that the discharge capacity of the nano-composite could reach 279 mAh/g at a 0.4 A/g current density, being about 96.5% of the theoretical capacity for β-Ni(OH)₂. When the current density was increased from 0.4 to 8 A/g, the capacity of the hybrid capacitor could remain about 76.5%. The nano-composite showed an excellent high rate charge-discharge performance and furthermore a high electrochemical reversibility. The AC/NiOOH electrochemical hybrid capacitor using this nano-composite could be activated quickly and possessed high charge-discharge efficiency and good cycle performance.