Self-Assembled Hollow Metal Sulfide Materials And Its Applications In Supercapacitors

As we all know,energy storage materials play an increasingly significant role in daily life,and supercapacitors stand out among many energy storage materials due to their higher theoretical capacity density,fast charge-discharge reaction,and superior cycle performance.Commonly used supercapacitor electrode materials include carbon-based materials,conductive polymer materials and transition metal compound materials.Traditional carbon-based materials have high electronic conductivity,but rearrangement may occur during charging and discharging and affect the stability of their electrochemical performance.The conductive polymer material is easy to process and the conductivity can be adjusted,but its original structure may collapse during long-term charge and discharge.The transition metal sulfide has flexible valence,high specific capacity,and good reversibility,which can avoid the disadvantages of the above materials to a certain extent.The development of its ultrahigh theoretical capacitance is very little,indicating that there is a lot of room for improvement in the preparation of transition metal sulfide materials and electrode production.Therefore,this thesis selects transition metal sulfide as the active material of the electrode for research,and explores the effect of two different electrode preparation methods on the performance of the material.Details are as follows:Firstly,in this thesis,the methacrylic acid group with the smallest semi-rigid structure having both hydrophilic groups and lipophilic groups is selected as the ligand to coordinate with metal ions to form a stable precursor solution.Self-assembly uses water and ethanol as the solvent,and thiourea is used as the sulfur source.The addition of ethanol causes the desolvation of the ions in the solution to perform molecular self-assembly under the inducing of hydrogen bonding,and then forms a kind of hollow metal sulfide after one-pot solvothermal method.Using this as the active material of the working electrode,its electrochemical performance was tested using two different electrode fabrication methods.In addition,it has superior performance compared with commercial CuS and CuS working electrode materials in the literature.Secondly,on this basis,we explored Cu2+ as the main ion,introduced precursor solutions of various transition metal ions of Co2+,Zn2+,Ni2+,using thiourea as the sulfur source,and prepared Cu-Co,Cu-Zn,and Cu-Ni working electrodes complete the construction of binary metal sulfides to achieve the goal of improving their electrochemical performance using the one-pot solvothermal method.In addition,the influence of the preparation temperature on the electrochemical performance of the working electrode was explored,and then two different methods for preparing the working electrode were selected.Based on the predecessors' methods,we were innovated and conformed it to a green and environmentally friendly synthesis strategy.The method can be applied to three or more transition metals,which fully shows that the method has certain universality,and it is different in introducing different transition metal elements,but all of them have improved electrochemical performance to varying degrees.In short,this method is simple to manufacture,environmentally friendly and the prepared material has excellent electrochemical properties.The results show that the Cu-Ni working electrode fabricated as a supercapacitor can reach a capacitance of 2070 m F/cm~2 at 1 m A/cm~2.