Nickel oxide/hydroxide nanoplatelets synthesized by chemical precipitation for electrochemical capacitors

Nickel hydroxide powder prepared by directly chemical precipitation method at room temperature has a nanoplatelet-like morphology and could be converted into nickel oxide at annealing temperature higher than 300 degrees C, confirmed by the thermal gravimetric analysis and X-ray diffraction. Annealing temperature influences significantly both the electrical conductivity and the specific surface area of nickel oxide/hydroxide powder, and consequently determines the capacitor behavior. Electrochemical capacitive behavior of the synthesized nickel hydroxide/oxide film is investigated by cyclic voltammetry and electrochemical impedance spectroscope methods. After 300 degrees C annealing, the highest specific capacitance of 108 Fg(-1) is obtained at scan rate of 10 mVs(-1). When annealing temperature is lower than 300 degrees C, the electrical conductivity of nickel hydroxide dominates primarily the capacitive behavior. When annealing temperature is higher than 300 degrees C, both electrical conductivity and specific surface area of the nickel oxide dominate the capacitive behavior. (c) 2007 Elsevier Ltd. All rights reserved.