Preparation And Electrochemical Performance Of Composite Electrode Based On Ti₃C₂ MXene/MoS₂

As a new type of energy storage device,supercapacitors have been a hot spot in energy storage research in recent years.However,the low energy density of supercapacitors hinders its practical application.The research of improving energy on supercapacitors has great significance.The electrode material in the supercapacitor mainly carries the function of storing and transferring charge,and its capacity has a great influence on the energy density.Among the existing electrode materials,Mo S₂is a two-dimensional transition metal sulfide,with a high theoretical specific capacitance,and its unique two-dimensional structure provides a good channel for ion transport.However,the low conductivity of Mo S₂makes it unable to transfer charge quickly during the energy storage process,resulting in limited capacity.Adding a material with good conductivity to the electrode material helps to increase the capacity.The conductivity of Ti₃C₂ MXene reaches 5700 S cm^-1,which is an ideal material for improving the electrochemical performance of Mo S₂.Therefore,based on the research of Mo S₂nanoflowers,this article uses chemical etching to prepare Ti₃C₂ MXene.Two methods are used to prepare Ti₃C₂ MXene/Mo S₂composite electrode materials,and compare the specific capacitance and cyclic charge and discharge performance of two different Ti₃C₂ MXene/Mo S₂composite electrode;In addition,the composite material is used as a positive electrode to assemble a supercapacitor,and the energy storage mechanism and practical application are analyzed.The results obtained are as follows:(1)Ti₃C₂ MXene was prepared by chemical etching,and the influence of water bath temperature and reaction time on the morphology of Ti₃C₂ MXene was studied;As the temperature of the water bath increased from 20?to 60?,the morphology of Ti₃C₂ MXene changed from blocky to accordion-like to a large amount of debris on the surface,and when the reaction time increased from 24 h to 120 h,The morphology of Ti₃C₂ MXene has been over-etched.Finally,it was determined that the optimal temperature for synthesizing Ti₃C₂ MXene was 40?and the time was 48 h.(2)The multi-layer Ti₃C₂ MXene was subjected to ultrasonic dispersion treatment to obtain a d-Ti₃C₂ MXene with a thickness of 4 nm,transparency and abundant surface functional groups.Then the Ti₃C₂ MXene coated Mo S₂nanoflower composite material was obtained by mechanical ultrasonic treatment.The influence of the composition ratio on the electrochemical performance of the Ti₃C₂ MXene/Mo S₂composite electrode was studied.The results showed that with the increase of the Ti₃C₂ MXene content,the specific capacitance of the composite material first increased and then gradually decreased.The best Mo S₂/Ti₃C₂ MXene mass ratio is 3:1,The specific capacitance of the composite electrode reaches 238.02F g^-1.Compared with the pure Mo S₂nanoflower electrode,the internal resistance of the composite electrode is reduced,and the specific capacitance is increased by 2.71 times.And the capacitance of the composite electrode maintained 85%after 5000 cycles of charge and discharge.(3)A one-step hydrothermal method was used to grow Mo S₂nanosheets on Ti₃C₂ MXene to prepare composite electrode materials,and the effect of the addition of Ti₃C₂ MXene on the electrochemical performance was studied;The results show that as the amount of Ti₃C₂ MXene increases,the electrochemical performance of the composite electrode shows a trend of first increase and then decrease.The best composite ratio electrode can be obtained at the ratio of 10 ml Ti₃C₂ MXene,and the voltage window of the electrode is 0.55 V The specific capacitance is 527 F g^-1.When the current density is 1 A g^-1,the composite electrode can still maintain 80%of the initial capacity even after 2000 cycles of charge and discharge.(4)With Ti₃C₂ MXene/Mo S₂composite material as the positive electrode and activated carbon(AC)as the negative electrode,Ti₃C₂ MXene/Mo S₂//AC quasi-solid supercapacitors were assembled.The results show that the voltage window of the quasi-solid supercapacitor is0.8 V,the specific capacity is 112.5 F g^-1,and the capacitance retention is 68%after 5000cycles of charge and discharge.The series and parallel test of the capacitor shows that the working voltage and specific capacity of the Ti₃C₂ MXene/Mo S₂//AC capacitor have been greatly improved,and it can drive the LED lamp with a rated voltage of 1.8 V to work for seven minutes,indicating that the prepared quasi-solid super Capacitors have a certain practicability.