The Study And Preparation Of Nano Ni-Co Sulfide With Solvothermal Method As Supercapacitors

Supercapacitor is a standard low carbon economy core product, which has known as the gold capacitor. Transition metal chalcogenides as the electrode material of supercapacitor has good electrical conductivity and high theoretical specific capacitance. This paper introduces characteristic, working mechanism, applications and the component and assembly of supercapacitor device. Meanwhile, the preparation methodes and tne latest progress of transition metal chalcogenides in chemical supercapacitors were reviewed. Nano were prepared by solvothermal method. The compositon and crystal morphology of nickel cobalt sulfide was detected by XRD, SEM, EDS. A single electrode material was prepared by coating or growing on the graphite paper, which used as the anode electrode of supercapacitor device. The electrochemical performance was studied through cyclic voltammetry(CVs), chronopotentiometry(CP) and electrochemical impedance spectroscopy(EIS). The main contents are as follows:① Preparation of nano nickel cobalt sulfide powder with the different precursor through solvothermal was achieved in this paper. According to the SEM, the morphology of nickel cobalt sulfide prepared by different precursor salts is similar, and the difference of particle sizes is small. The nickel cobalt sulfides microspheres prepared with nitrate dispersed uniformly. There were small particles in the surface, providing larger specific surface area, thereby increasing the contact of the electrolyte and electrode materials. This will benefit to the enhancement of the electrochemical performance. And the nickel cobalt sulfides microspheres prepared with chloride microspheres have a tendency to reunite, which led to the small specific surface area. The electrochemical performance was tested, and the result showed that the electrode with nitrate presented specific capacitance of 2213.5 F/g, 2107.6 F/g, 2009.4 F/g, 1957.5 F/g, 1806.4 F/g and the electrode with chlorate is 1309 F/g、1100 F/g、782 F/g、682 F/g、409 F/g at discharge current density of 2 m A/cm2, 4 m A/cm2, 8 m A/cm2, 10 m A/cm2, 20 m A/cm2, respectively, which showed ultrahigh capacitance. And the electrode with nitrate’s maximum capacitance retained 90%, the electrode with chloride’s maximum capacitance retained 46% after 3000 cycles at a charge and discharge current density of 10 m A/cm2.Nano nickel cobalt sulfide growth directly on the graphite substrate interwoven with small particles and nanosheet structure in liquid phase reaction system was achieved. The experimental results indicated that the supercapacitors characteristics of nickel cobalt sulfide were mainly due to pseudocapacitance. Nano nickel cobalt sulfide /graphite paper electrode exhibited excellent pseudocapacitances of 1500 F/g, 1450 F/g, 1340 F/g, 1120 F/g, 1055 F/g, 900 F/g, 800 F/g, 662 F/g, 557 F/g during charge-discharge current density of 1 m A/cm2, 2 m A/cm2, 4m A/cm2, 8 m A/cm2, 10 m A/cm2, 15 m A/cm2, 20 m A/cm2, 25 m A/cm2, 30 m A/cm2. Meanwhile, it showed the superiority of cycle stability. After 3000 cycles at a charge and discharge current density of 10 m A/cm2, specific capacitance retention rate reached 97.2%.In this paper, by comparing the optimization, the best active material was selected as the anode material for flat asymmetric micro-supercapacitor. The device has higher energy density and power density. After 10000 cycles, cycle stability of the device remained 98.1% and coulomb efficiency also retained at 92.7%. This research developed planar structure of supercapacitor. The assembly method of the device was so simple and facile that it can be applied for the preparation and assembly of other materials.