Electrodeposition Of Cobalt Oxide For Supercapacitors

Supercapacitor is a new kind of energy storage device with the advantages of high power density,long cycle life and etc.New electrode materials' study is a good way to improve performance of supercapacitor as it depends mainly on electrode materials.Cobalt oxide has potential applications due to its high theoretical specific capacitance,abundant resources,environmentally friendly and low cost.However,its application was restricted by the disadvantages of low electrical conductivity,low surface area and low stability.In this work,electrodeposition of cobalt oxide was conducted on graphite(G),functionalized exfoliated graphite(FEG)prepared by a controlled two-step partial exfoliation method and functionalized graphite prepared in 4-toluene sulfonic acid solution(PEG).Influences of higher potential limit in cyclic voltametry for cobalt oxide deposition,CH3COONH4 concentration and substrate on the electrodeposition of cobalt oxide were studied.The obtained cobalt oxide was characterized by by scanning electron microscope(SEM),X-ray diffraction(XRD)and fourier transform infrared spectroscopy(FT-IR).Electrochemical properties of the cobalt oxide were studied by CV,galvanostatic charge/discharge experiments(CP)and electrochemical impedance spectroscopy(EIS).It was found that the FEG/CoO_x-12-01 electrodeposited by CV scans from-1.2 to 1.2 V at 100 mV s-1 in 0.04 M Co(NO3)2 and 0.1 M CH3COONH4 aqueous solution on FEG displayed good capacitive performance.Opened structures were constructed by cobalt oxide nanosheets in FEG/CoO_x-12-01,which can facilitate the contact of electrode materials with electrolyte and enhance its electroactivity and charge storage property.FEG/CoO_x-12-01 displayed a high specific capacitance of 678 F/g at 1 A/g.No capacitance decay was detected for FEG/CoO_x-12-01 after 10000 galvanostatic charge/discharge cycles,showing its excellent stability.