Preparation And Electrochemical Properties Of Molybdenum Disulfide Electrodes Based On Commercial Carbon Cloth

Supercapacitors have been widely used in national defense,transportation,aerospace and military affairs due to their unique characteristics including fast charging and discharging,high power density,and extremely stable electrochemical performance.Nowadays,the supercapacitors have move toward bendable,foldable and flexible direction to meet the requirement of fast development of portable wearable electronic devices.In order to obtain high performance flexible supercapacitor,the key is the design of advanced electrode materials.In this thesis,the commercially available carbon cloth(CC)was applied as the flexible substrate to grow molybdenum disulphide(MoS2)to obtain flexible CC-MoS2 electrode for supercapacitor application.Following this work,the conductive polymer(3,4-ethylene dioxythiophene)(PEDOT)was coated on CC-MoS2 electrode in order to further improve its conductivity.In chapter ?,the CC was firstly treated with mixed acid to enhance its wettability,and the functionalization of CC with PDDA is to make the carbon fiber surface positively charged.The PDDA functionalized CC electrostatically adsorb Mo70246-dissolved in DMF,and the subsequent solvothermal reaction yield the CC-Mo precursor.Finally,the precursor was converted into CC-MoS2 by a post high-temperature sulfidation process.When the mass loading of MoS2 is 4.8 mg cm-2,the MoS2 nanobelts are strongly coupled with the carbon fibers to form a hierarchical network,which enables easy penetration of electrolyte into the interior of electrode and shortened the ion transport path.The electrochemical test results show that the area capacitance of the CC-MoS2-2 electrode is 2730 mF cm-2 and the specific capacitance of the MoS2 is 568 F g-1 at the current density of 5 mA cm-2.When the current density increased to 15 mA cm-2,the electrode has a capacitance retention of 59%.After continuous galvanostatic charging-discharging of 10000 cycles at 30 mA cm-2,the electrode capacitance retention is 75%,while the Coulombic efficiency can reach 99%.The morphology and structure after cycling remains nearly intact as compared with the pristine electrode before cycling,indicating that the CC-MoS2-2 electrode material has great structural and electrochemical stability.In addition,CC-MoS2-2 electrode has good mechanical property,the tensile stress can reach 5.3 Mpa when the tensile strain is 9%.Meanwhile,it can be twisted and rolled into any shape without obvious structural collapse.CC-MoS2-2 composite electrode material can also be used as anode material in lithium ion capacitors.Within the voltage window of 0.1-3.0 V,the discharge capacitance of CC-MoS2-2 electrode material reach 2703 mAh g-1 at 0.1 C.After 50 cycles,its capacity remains at 2288 mAh g-1,which retains 85%of its initial capacitance.In chapter IV,PEDOT conductive polymer was coated on the surface of CC-MoS2-2 electrode material by potentiostat electrodeposition technology.When the deposition time is 5 min,PEDOT forms a uniform film on the surface of CC-MoS2-2,which improves the conductivity of the electrode and the utilization rate of active substances,thus improving the rate performance and specific capacitance of the electrode material.At the current density of 5 mA cm-2,the electrode material delivers a specific areal capacitance is 3628 mF cm-2.When the current density increased to 15 mA cm-2,the capacitance retention reaches 80%.After continuous galvanostatic charging-discharging of 10000 cycles at 30 mA cm-2,the electrode capacitance retention is 83%,while the Coulombic efficiency can reach 100%.In addition,the 3D-network structure of PEDOT can enhances the mechanical properties of the electrode material,the tensile strain reaches 12%.