Preparation Of Metal Sulfides And Their Composite Nanomaterials For Lithium Storage

To speed up the lithium-ion batteries(LIBs)applications in electric vehicles and hybrid electric vehicles,a key lies in exploiting novel electrode materials with high energy/power densities and long cycle life to replace the commercial graphite anode(theoretical value: 372 m Ah g-1).So,it becomesimperative to seek the other anode materials.Nowadays,the research showed that the metal sulfides have very high theoretical capacity,such as Mo S2(the theory capacity is 670 m Ah g-1).However,they are very easy to stack/restack into the bulk materials,leading to the limited space for lithium ion storage at high rates particularly.This paper was mainly through the above two aspects to improve the performance of lithium-ion batteries,the main contents are as follows:(1)It is to construct the new nanostructure,which could avoid the stacking/restacking of materials and leaveenough space for solving the problems that related to the volume expansion during the charge and discharge process.(2)By combining with other nanomaterials,such as graphene,metal oxides,and metal sulfides,which could improve the electronic conductivity of nanomaterials during charge/discharge process andenable better chemical and electrical synergistic effect.This paper mainly through the above two aspects to improve all aspects of metal sulfide in lithium ion battery performance,and the main contents are as follows:1.Three-dimensional(3D)hierarchical nanosheet-based Mo S2 nanotubes were synthesized by self-sacrificial template method.Theformation mechanism of the nanotube was researched.The as-prepared nanosheet-based Mo S2 nanotubes anodes exhibited excellent electrochemical performance.In order to confirm the structural stability and show the electrochemistry during lithiation–delithiation,the structure and composition of the Mo S2 nanotubes after cycling were investigated.2.The method of universal applicability above was verified.This chapter used the same method to synthesize two-dimensional nanosheets-based on porous nanosheets.The porous Mo S2 nanosheets after the thermal treatment were also synthesized.The superior electrochemical properties were studied by comparing with Mo S2 nanotubes and porous Mo S2 nanosheets before and after calcination.In order to confirm the structural stabilityand show the electrochemistry performance during lithiation–delithiation,the structure and composition of the calcined porous Mo S2 nanosheets after cycling were investigated.3.This chapter mainly through two steps solvothermal method to fabricate Co9S8@Mo S2/r GO.The Mo S2 nanosheets grew on the surface of Co9S8,and formed the core-shell nanostructure.Meanwhile,the binary compounds(Co9S8/r GO)were synthesized in order to explore the mechanismduring lithiation/delithiation.It can highlight the superiorty of core-shell nanostructure by comparing with the electrochemistry performance of Co9S8/r GO and Co9S8@Mo S2/r GO.In order to confirm the structural stability and show the electrochemistry performance during lithiation–delithiation,the structure and composition of Co9S8@Mo S2/r GO after cycling were investigated.