Preparation And Electrochemical Properties Of Transition Metal Nickel-cobalt-manganese-based Sulfide Composite Electrode Materials For Supercapacitors

With population growth and rapid economic development,energy demand growth has become the driving force of energy storage technology development.Among all energy storage devices,supercapacitors have attracted wide attention due to their advantages such as higher cycle life,power density,faster redox reaction,environmental friendliness and low cost.The excellent electrochemical performance of supercapacitors depends to a certain extent on the structure design and electrode material composition.To same extent,the superior electrochemical performance of supercapacitors depends on the structure design and electrode material composition.Transition metal sulfides have been widely studied as electrode materials for battery-type supercapacitors due to their higher conductivity and richer electroactive potentials.In this paper,nickel sulfide/nickel foan(NiS/NF),nickel-cobalt-manganese sulfide/nickel foam(Ni-Co-Mn-S_x/NF)and nickel-cobalt-manganese sulfide/nickel sulfide/nickel foam(Ni-Co-Mn-S_x/NiS/NF)composite electrode materials were successfully prepared and studied by electrochemical deposition synthesis method.The phase,morphologies and electrochemical properties of the composite electrode materials were characterized.The main research contents are as follows:(1)The effects of nickel sulfate concentration,thiourea concentration,temperature and deposition time on the electrochemical properties of NiS/NF electrode materials were studied.The results showed that when the nickel sulfide concentration was 0.01 M,the thiourea concentration was 0.75 M,the temperature was 40?,and the deposition time was 5 min,the performance of NiS/NF electrode material reached the maximum,and its specific capacitance value reached 1524.3 F/g when the current density was 1 A/g.After 3000 cycles,the capacitance retention could reach 79.2%of the initial value.(2)The effects of cobalt sulfate concentration,manganese sulfate concentration,nickel sulfate concentration,thiourea concentration,temperature and deposition time on the electrochemical performance of Ni-Co-Mn-S_x/NF electrode materials were studied.The morphology and structural and electrochemical properties of the as-prepared Ni-Co-Mn-S_x/NF were analyzed by the relevant characterization techniques,and the formation mechanism was proposed.The prepared flake amorphous Ni-Co-Mn-S_x/NF electrode material showed an ultra-high specific capacitance of 2687.5 F/g at the current density of 1 A/g,and the capacitance retention reached 85.2%of the initial value after 3000 cycles at the current density of 10 A/g.(3)The Ni-Co-Mn-S_x/NiS/NF nanosheet arrays were successfully prepared by two-step deposition,showing a nanoscale composite structure with a large specific surface area.The composite electrode material shows a large specific capacitance of3235 F/g at the current density of 1 A/g,and 84.3%capacitance retention rate after3000 cycles at the current density of 10 A/g.