Preparation And Characterization Of Transition Metal Selenides Electrodes Materials And Its Application In Supercapacitor

In recent years,with the improvement of living standards,people's research on supercapacitor technology has become more and more mature,and small-capacity and large-capacity supercapacitors have been rapidly developed.In order to enable a supercapacitor with a wide range like a lithium ion battery,increasing its energy density is an indispensable process.Widening its voltage window and increasing specific capacity are effective ways to increase energy density.In this paper,the method of increasing the energy density is explored by preparing the transition metal selenide electrode material with special morphology to study the relationship between structure and properties.Therefore,one-step solvothermal method was used to prepare a transition metal selenide electrode material with non-stoichiometric ratio.The relationship between the morphologies and structures of electrode materials and their electrochemical performance is investigated in detail.The main work was as follows:1.Ni_0.85Se nanoparticles with uniform morphology were successfully synthesized by one-step solvothermal method without any surfactant and template.The prepared Ni_0.85Se nanoparticles were characterized by XRD,SEM,TEM,XPS and BET.It was found that the Ni_0.85Se nanoparticles prepared by using benzyl alcohol as a solvent have uniform morphology,the diameter of these nanoparticles is approximately 30 nm.The electrochemical performance tests of the Ni_0.85Se nanoparticles showed that the Ni_0.85Se nanoparticles showed high specific capacity and excellent rate performance.It has a specific capacity of up to 114.6 mA h g^-1 at a current density of 1 A g^-1.It has a capacitance retention of 73.9%after 5000 cycles of charge and discharge at a current density of 5 A g^-1,demonstrating good cycle stability.2.Ultra-thin Co_0.85Se nanosheets were successfully synthesized by one-step mixed solvothermal method without any surfactant and template.The prepared Co_0.85Se nanosheets were characterized by XRD and SEM.It found that the Co_0.85Se-1 nanosheets prepared in V_DETA:V_DMF=2:1 are not only thin,but also have abundant pores.The electrochemical performance of the prepared samples showed that the capacitance retention rate was 73.2%when the current density was from 1 A g^-1 to 10 A g^-1.The results show that the Co_0.85Se-1 nanosheet has excellent rate performance.3.The synthesized Ni_0.85Se nanoparticles and the porous ultra-thin Co_0.85Se-1nanosheet were used as the positive electrode material,the activated carbon was used as the negative electrode material,and the KOH solution?2 M?was used as the electrolyte to assemble the supercapacitor device.Both Ni_0.85Se//AC ASC and Co_0.85Se-1//AC ASC were found to exhibit excellent electrochemical performance.The supercapacitor device is then used as the power source for the LED lamp,connected into a complete circuit loop,and it is found that the LED lamp can emit light.