Preparation And Electrochemical Performance Of Transition Metal Sulphide Composite Carbon Nanomaterials

Supercapacitor,also called as electrochemical capacitor,is an energy storage device with an unlimited life-cycle and high power density,which usually stores energy in the form of the double-layer or supercapacitance.It is a novel power devices,whose energy and power densities are between these of batteries and conventional dielectric capacitors and is applied to the field of computer power back-up,electric vehicles and power electronics.Electrode materials are the core factors to influence the electrochemical performance of supercapacitors.Therefore,in the research of supercapacitors,the preparation of high-performance electrode materials always becomes the focus of researchers.In this thesis,two kinds of metal sulfides?CoS and MoS₂?are prepared by hydrothermal method and used as supercapacitor electrode materials.In addition,in order to overcome the shortcomings of metal sulfide,the metal sulfide is compounded with carbon nanomaterials to plays the synergistic effect of the materials.The preparation and electrochemical properties of the composites are systematically studied.The main research contents and conclusions are as follows:CoS@CNTs/rGO ternary composites are prepared by hydrothermal method and freeze-drying with glucose as reducer.The structure and electrochemical performance of the material are investigated.FESEM image shows that in the CoS@CNTs/rGO ternary composites,the platelet-shaped CoS is uniformly dispersed in the three-dimensional CNTs and rGO conductive framework structures to form a three-dimensional structure.This structure promotes the transport of electrolyte ions and improves the electrochemical performance.Electrochemical performance tests show that the CoS@CNTs/rGO ternary composite has a high specific capacitance of 295 F/g at the current density of 1.0 A/g;After a constant current charge/discharge of 2000 cycles at the same current density,the specific capacitance retention rate is 77.41%;The specific capacitance is 235 F/g at a current density of 5.0 A/g.The above results show that the ternary composite has better capacitance performance.The MoS₂@CNTs/rGO ternary composites are in situ synthesized by a simple hydrothermal method and reduction process.The characterization test results show that the three components are uniformly distributed in the MoS₂@CNTs/rGO ternary composites.The graphene-carbon nanotubes are used as the carbon frame to effectively support the MoS₂@CNTs/rGO ternary composite,therefore the supercapacitor performance is improved effectively.Electrochemical performance tests show that the specific capacitance of MoS₂@CNTs/rGO reaches 218 F g^-1 at a scan rate of 100 mV/s.Even after 3000 times cycls at a scan rate of 10 mV/s,the specific capacitance can still reach 364 F g^-1 with a high specific capacitance retention rate?83.1%?.