Modification Of Nickel Oxide Electrode Material And Electrolyte Investigation On Supercapacitor

The supercapacitor is a new type of electrochemical energy storage devices between the typical rechargeable batteries and the typical dielectric capacitors and have advantages of high power densities and have very long cycle life, and have drawn more and more attention in recent years. The dissertation focus on the preparation, structure properties of electrode material and study on electrochemical hybrid supercapacitors composed with activated carbon and nickel oxide electrodes.The effects of different electrolytes on capacitor properties of NiO were investigated. Nickel oxide film electrodes be have pseudocapacitance in aqu eous KOH.The results showed that the KOH electrolyte ware feasible. LiO H additives were studied. On the condition of 5mA·cm^-2 constant current, t he specific capacitance is 369.75F·g^-1 in mixed electrolytes containing 4.5m ol KOH and 0.5mol LiOH every one litre. The cycle capability of NiO in mixed electrolytes is excellent.NiO was prepared by depositing methods. Taking (NH)₂CO₃ as precipit ator, the NiO was prepared by Parallel Flow Precipitation Process, The val ues of R_L and R_E by test of AC impedance are 0.5Ωand 0.6Ωrespectivel y.The specific discharge capacitance is 352.7 F·g^-1 at 10mA·cm^-2 current de nsity. Long cycle life was also demonstrated after charge/discharge 100 cyc les at 12 mA·cm^-2.Taking Ni(NO₃)₂ and (NH)₂CO₃ as main raw materials, taking PEG-400 as surfactant, NiO was prepared by alcohol-water method. Compared with water solution method, the distribution of the NiO powder obtained by alcohol-water method is narrow. The addition of surfactant PE G-400 can reduce powder agglomeration. The specific capacitance of the re suiting NiO reached 395.5 F·g^-1 at 10mA·cm^-2. NiO was prepared that multi-ion instituted the Ni²⁺ by alcohol-water m ethod. By using orthogonal test method optimum technological conditions ar e Al³⁺:Zn²⁺:Co²⁺=0.88:0.05:0.02:0.05.The specific capacitance of the resultin g NiO reached 716.45 F·g^-1 at 10mA·cm^-2.XRD and SEM show that particl e size of the NiO is smaller and its distribution is narrow.Electrochemical hybrid supercapacitor composed with activated carbon and nickel oxide electrodes were studied in 5mol·L^-1 KOH aqueous solutions.The result: The maximum charge-discharge voltage was about 1.45V and excellent characteristic of high power discharge was attained in this way. This type of hybrid supercapacitor exhibited much lower self-discharge rate than capacitor composed of two identical activated carbon electrodes. The specific capacitance of electrochemical hybrid supercapacitor reached 82.68F·g^-1 at 10mA·cm^-2 on quality proportion of anodexathode is 4:1, its inner resistance is 0.45Ωat different current density. Long cycle life was also demonstrated after charge/discharge 5000 cycles, and its specific capacitance is above 80% initiatory capacitance. The high performance obtained indicates that the AC/NiO hybrid supercapacitorsare promising.