Construction Of Multilayer Structure Of Manganese-cobalt Sulfide And Study On Energy Storage Performance

Based on the background of sustainable green development,it has become the key to solve the existing issues of energy by tapping renewable and clean energy sources and enhancing the utilization of clean energy.Among them,with the development of new materials and preparation technologies,supercapacitors as high-power energy storage devices are considered to be one of the most promising energy storage devices to replace lithium batteries.Among many energy storage materials,transition metal sulfides have attracted extensive attention from researchers due to their high electrochemical activity,conductivity,and structural diversity.However,the intrinsic characteristics of the sulfide structure may lead to volume expansion and structural collapse during charge storage and release,resulting in a series of problems such as low coulomb efficiency and reduced service life.The construction of 3D multi-level transition metal sulfide composites through reasonable structural design provides a new way to solve the above problems.Therefore,this paper takes material morphology control engineering as the main line,and expects to obtain advanced transition metal sulfide electrode materials with high capacity,high load and long cycle life by regulating the form and structure composition of the composite.This thesis contains two main parts as follows:（1）The MCS/NCS composites with 3D mesh structure were constructed by hydrothermal and simple electrodeposition synthesis method with 2D nanosheets as the basic building blocks,and the effect of the electrodeposition process on the material morphological structure during the material composite was investigated.In particular,the three-dimensional network structure of MCS/NCS also exhibits certain characteristics of porous structure and has a great specific surface area of 5.965 m²·g^-1 compared with the two-dimensional MCS nanosheet array.the multilayer structure of MCS/NCS-6 exhibits a high specific capacity of 255.6 m Ah·g^-1at a current density of 1A·g^-1,while still having 88.5%capacity after 5000 cycles.The retention rate proves that a reasonable structural design can improve the volume expansion problem during charging and discharging.The asymmetric device MCS/NCS-6//AC assembled with its positive electrode has a high energy density of 45.6 Wh·kg^-1 and a capacity retention rate of75.6%.（2）Through the strategy of MOF derivatization and anion exchange,3D multi-level nanoflower-like NCM MOF/NCM-S composites were constructed on conductive substrates with 1D nanowires and 0D nanospheres as building blocks.The effects of metal ion ratio and vulcanization process on the morphology and properties of the composites were investigated.Among them,the optimized NCM-S-160 composite exhibited significantly enhanced capacitance performance(400.0 m Ah·g^-1,1 A·g^-1)and multiplicity performance(52.0%,10A·g^-1),while the highly loaded(4.0 mg·cm^-2)NCM-S-160 exhibited 94.2%capacity retention even after 5000 cycles.In addition,the asymmetric device NCM MOF/NCM-S//AC also exhibits a high operating voltage（1.7 V）,high energy density(58.5 Wh·kg^-1)and high capacity retention（81.8%,5000 cycles）.