Preparation And Capacitance Properties Of Transition Metal Sulfide Electrode Materials

With the development of economy and the progress of science and technology,the demand for electronic energy storage devices with high energy density,high safety performance,environmental protection and low cost is increasing.Compared with battery,supercapacitor has the advantages of short charge and discharge time,high power density and long cycle life.However,it also has the disadvantage of low energy density,which limits its practical application.As the core part of supercapacitor,electrode material plays a decisive role in energy density.Therefore,the development of electrode materials with high energy density and high power density can effectively improve the performance of supercapacitors.In this paper,cobalt based bimetallic sulfide electrode materials were prepared by hydrothermal reaction and high temperature calcination1.Preparation of nickel cobalt sulfide electrode material and its supercapacitor performance.NiCo₂S₄was prepared by a simple one-step hydrothermal reaction.The morphology and composition of the materials were characterized by XRD,SEM,TEM,XPS and BET.The electrochemical properties of NiCo₂S₄were tested in three electrode system.The results show that the specific capacitance of NiCo₂S₄is 564.7 F g^-1at the current density of 1 A g^-1.After5000 cycles,the capacitance retention rate is 82.5%,which has excellent cycle stability.When the power density is 0.75 k W kg^-1,the energy density is67.5 Wh kg^-1,and when the energy density is 46.0 Wh kg^-1,the power density is 7.5 k W kg^-1.2.Preparation of nickel cobalt sulfid/graphene electrode material and its supercapacitor performance.A series of NiCo₂S₄/RGO materials were prepared by adding different amounts of graphene into NiCo₂S₄materials.The morphology and composition of the material were studied by physical characterization.The results show that NiCo₂S₄/RGO-0.03 has a higher specific surface area of33.92 m²g^-1.The results show that NiCo₂S₄/RGO-0.03 has excellent specific capacitance(0.5 A g^-1?1037.9 F g^-1,10 A g^-1?668.9 F g^-1)and good cycle stability(the capacitance retention is 86.6%after 5000 cycles at a current density of 1 A g^-1).When NiCo₂S₄/RGO-0.03//AC asymmetric capacitor is assembled with negative electrode material AC,it still has excellent performance.When the power density is 0.6 k W kg^-1and 4.1 k W kg^-1,the energy density is 119.6 Wh kg^-1and 84 Wh kg^-1,respectively.3.Preparation of cobalt iron sulfide/nitrogen doped graphene electrode materials and their supercapacitor properties.Co₈Fe S₈/NGO materials were synthesized by simple hydrothermal reaction and high temperature calcination with ethylenediamine as nitrogen source.The characterization results show that the composite has good charge transfer ability.The electrochemical test results show that the specific capacitance of Co₈Fe S₈/NGO is 773.5 F g^-1when the current density is 1 A g^-1.After 5000 cycles at 1 A g^-1,the capacitance retention is 85.23%.The supercapacitor with Co₈Fe S₈/NGO material as positive electrode and activated carbon as negative electrode has a power density of 6.9 k W kg^-1at an energy density of 38.9 Wh kg^-1and a energy density of 66.5 Wh kg^-1at a power density of 0.7 k W kg^-1.