Preparation and characterization of the electrodeposited Ni-Co oxide thin films for electrochemical capacitors

Nickel-cobalt (Ni-Co) oxide thin films were electrodeposited onto copper substrates in an electrolyte containing cobalt chloride and nickel chloride, and the electrochemical capacitor behaviors of these films were investigated. The XRD pattern revealed that the electrodeposited Ni-Co oxide thin film was comprised of NiCo 2 O 4 . In the SEM image, the electrodeposited Ni-Co oxide film was covered with hexagonal and cubical shaped particles. The electrodeposited Ni-Co oxide electrode exhibited a specific capacitance of 148 F/g at a scan rate of 20 mV, and the current density was fairly stable over 200 cycles. The charge-discharge test confirmed that capacitance of the electrodeposited Ni-Co oxide electrode resulted from the electric double layer capacitance and pseudocapacitance.