Effects of Different Substrates and Anneal Temperatures on the Nanoflakes Co(OH)2 Porous Films for Electrochemical Capacitance

The nanoflakes Co(OH)2 porous films have been successfully electrodeposited on nickel foam and nickel foil substrates from cobalt nitrate dissolved in water–ethanol (1:1 volume ratio). Field emission scanning electron microscope (FESEM) studies present that the as-deposited films have an interlaced nanoflakes porous surface morphology. Various electrochemical test results show that the films on both substrates exhibit excellent electrochemical capacitive behavior due to the special nanoflakes porous structure. Furthermore, it is obvious that the nanoflakes films on nickel foam substrate have much higher specific capacitance (maximum: 2369 F/g) than that of the films on nickel foil substrate (maximum: 255 F/g). Electrochemical techniques are used to systematically study the effects of anneal temperatures on the capacitance of the films for nickel foam substrate. The specific capacitance as high as 2913 F/g is achieved for anneal at 100 °C, indicating its potential application as a low-cost, high-performance electrode material in electrochemical capacitors.