Controlled Preparation And Electrochemical Properties Of Transition Metal Sulfide Nano-materials

As a new type of energy storage device,supercapacitor has the characteristics of high power density,long service life and environmental protection.However,the low energy density limits its development,and exploring new electrode materials is the key to solve this problem.Transition metal sulfides are a kind of important electrode materials for supercapacitors,which have abundant redox centers and high theoretical specific capacitance abundant reserves.The properties of transition metal sulfides are closely related to their composition,structure,size and morphology.Therefore,reasonable design and controllable preparation of transition metal sulfides with specific microstructure and morphology is one of the effective ways to improve their electrochemical performance.Cobalt sulfide,nickel sulfide and zinc sulfide are important transition metal sulfides with abundant reserves and low cost,which play an important role in the development of new electrode materials.This paper mainly focuses on the controllable preparation of nanostructures of cobalt sulfide,nickel sulfide and zinc sulfide,and the electrochemical properties of the corresponding materials studies was investigated at the same time.（1）CoS₂/Co₃S₄nanoflowers composed of nanosheets were prepared by decomposing[（C₄H₉）₂NCS₂]₂C_O]in the mixed solvent of dodecyl thiol（DT）and dodecylamine（DA）.The thickness of the nanosheets decreases by increasing the volume of DT in the mixed solvent.The electrochemical performance of the samples obtained with the volume ratio of DT/DA at 3:1,2:2 and 1:3 were evaluated.The results show that the sampleof DT/DA at 3:1 showed the best electrochemical performance The specific capacitance was 665 F g^-1at 1A g^-1,and the capacitance retention is 90%with the current density increasing from1A g^-1to 10 A g^-1.（2）NiS/Ni₃S₄composite nanostructures were prepared by decomposing[（C₄H₉）₂NCS₂]₂Ni precursor in the mixed solvent of DT and DA.The phase and morphology of the product changed with the volume atio of DT/DA.The product was composed of flowers with the volume ratio of DT/DA at 1:3,and When product was composed of nanoparticles with the volume ratio of DT/DA at 0:4,2:2 and 3:1.With the increase of DT volume in the mixed solvent,the size of the particles becomes larger and larger.The electrochemical test results show that the sample obtained with the volume ratio of DT/DA at 1:3 is the best,the specific capacity can reach 1242 F g^-1at1A g^-1the current density of 1 A g^-1.（3）Based on the solution-solid-solid growth,Ag₂S/ZnS nanowires with tunable bandgaps were prepared.The electrochemical test results show that the capacitance performance of the Ag₂S/ZnS nanowires is very poor,and could be improved in the future.