Activated Carbon Modified by CNTs/Ni-Co Oxide as Hybrid Electrode Materials for High Performance Supercapacitors

Hybrid materials of carbon nanotubes (CNTs) coated with nickel-cobalt (Ni-Co) oxide nanoparticles were synthesized using electroless plating. Transmission electron microscopy images showed that Ni-Co oxide nanoparticles were dispersively distributed on the external surface of CNTs. The composites of Ni-Co oxides modified CNTs were used as additives of activated carbon to improve the electrochemical performance of the electrode materials for supercapacitors. The electrochemical properties of the supercapacitors were investigated by galvanostatic charge-discharge, cyclic voltammetry, and alternating current impedance techniques. The maximum specific capacitance reached 215 F g^-1, approximately 23% higher than that without addition of the CNT-based composite, while the resistance of the electrode was also reduced by addition of the composite. The results revealed that the supercapacitor had an excellent charge-discharge cycle behavior and electrochemical stability after 1200 continuous cycles. The improved performance of the supercapacitor can be attributed to the modified structure and high electrical conductivity of the electrode materials due to the addition of the hybrid nanocomposite, which is promising for energy storage applications.