Preparation And Characterization Of Tin And Titanium Oxides With Nanostructure As Anode Materials For Lithium-Ion Batteries

Anode materials are regarded as an important component in lithium ion batteries?LIBs?,which have a crucial influence on LIBs`electrochemical performance.In this thesis,we have prepared a TiO₂anode material with a distinctive morphology,as well as two kinds of composites based on Sn/SnO₂ and TiO₂.Moreover,we have systematically investigated the structures,morphologies and electrochemical properties of the as-prepared materials.With the CNTs as template,we have prepared the TiO₂ mesoporous nanowires anode materials successfully.The as-prepared materials not only own the merits of the nanometer-sized materials,but also have the advantages of the sub-micrometer-sized materials.When tested as anode materials for LIBs,it exhibits a specific capacity of 151.0 mAh g^-1 after500 times at a current density of 200 mA g^-1.We have successfully prepared the mesoporous C-SnO_x@TiO₂core-shell nanospheres by two-step deposition methods and subsequently carbonization steps.The carbon in the structure can not only elevate the electric conductivity of the C-SnO_x@TiO₂ composite but also ease the stress caused by huge volume expansion of SnO_x during the charge/discharge processes.Meanwhile,the TiO₂ shell can prevent the reunite of the SnO_x nanoparticles efficiently.When tested as anode materials for LIBs,it exhibits a specific capacity of 466.4 mAh g^-1 after500 times at a current density of 800 mA g^-1.Even at higher current density of 2000 mA g^-1,the capacity of 377.0 mAh g^-1 can also be maintained after 1000 cycles.The yolk-like SnO₂@TiO₂ has been successfully prepared through an easy method.With the well-designed void space and the outside TiO₂shell,the as-prepared composite can effectively suppress the extreme volume expansion and the aggregation of SnO₂,enhancing the cycling stability of electrode structure.Moreover,the mesoporous structure of this composite can accelerate the diffusion of both electron and lithium ion by providing a high electrode-electrolyte contact area.When tested as an anode for lithium-ion batteries,the as-prepared composite showed a discharge capacity of 518.2 mAh g^-1 at a current density of 800 mA g^-1after 500 cycles.Even elevated the current density to 2000 mA g^-1,the capacity of 472.7 mA h g^-1 can still be obtained after 800 cycles.The excellent electrochemical performance is own to its well-designed void structure.