Controllable Synthesis Of Transition Metal Oxide And Sulfide As Anode Materials For Lithium Ion Batteries

Recently,Lithium ion batteries are widely used in the areas of mobile phones,cameras,laptops and other portable devices due to their advantages such as high safety,low price,high energy density and long service life.The rapid development of new generation vehicles,hybrid electric vehicles and other large electronic devices has put forward higher requirements for lithium-ion batteries.However,because of its low theoretical specific capacity,the commercialized graphite anode materials can not meet the requirements for the new generation of lithium ion batteries.Therefore,the development and design of anode materials with higher specific capacity and better safety have become an urgent task for the further development of lithium ion batteries.Thanks to the stable rate performance of rGO,high theoretical specific capacity of Molybdenum oxide and Molybdenum sulfide,those materials have a broad application prospect in the field of lithium ion battery anode materials.What's more,the morphology control and controllable synthesis of nanomaterials are often used to improve their electrochemical properties.In this thesis,we chose transition metal oxide and sulfide as lithium-ion battery anode materials for further study.And their morphology,structure and composition are analyzed by many characterization methods.The main work is as follows:1.The nanocomposite with a porous three-dimensional structure which consists of molybdenum dioxide nanodots anchored on the nitrogen/sulfur co-doped reduced graphene oxide(3D MoO2/NP-NSG)was fabricated by hydrothermal,lyophilization and thermal treatment.The obtained nanocomposite shows excellent electrochemical performance as anode material for LIBs.2.Polystrene spheres(PS)were synthesized through a simple emulsion polymerization process,and coated by titanium dioxide(TiO2)via a hydrolytic process(PS@TiO2).Then the molybdenum sulfide nanosheets grow on the surface of PS@TiO2 to achieve nanocomposites PS@TiO2@MoS2.At last,the PS core was carbonized into hollow carbon layer via high temperature carbonization treatment to obtain the three-layered C@TiO2@MoS2 hierarchical nanocomposites.These novel hybrids exhibit an enhanced lithium storage performance,when serving as anode materials in LIBs.