Controllable Preparation, Microstructure And Lithium Storage Properties Of Titanium-based Bimetallic Oxide Micro-nanostructures

With the development of technology,the demand for energy is increasing.Nowadays,owing to their relatively high energy density of rechargeable,long life and environmental friendliness,lithium-ion batteries(LIBs)have played an important role in energy storage technology and been widely applied in numerous electron devices including mobile phones,portable computers and electric automobiles and so on.Titanium-based oxide materials have been widely studied because of their high theoretical specific capacity,abundant resources and environmental friendliness.However,titanium-based metal oxides also have problems such as large volume changes and low conductivity during the charge and discharge process,resulting in poor cycling stability.Herein,the electrochemical properties of titanium-based metal oxide anode materials are improved by constructing porous microbar structure and carbon coated nanoparticles.The main research contents and results are as follows:(1)CoTiO₃nanoparticles(CTO NPs)and CoTiO₃microbars(CTO MBs)were synthesized by using a simple solvothermal method.The effects of microstructure on lithium storage properties were studied.When used as anode materials for LIBs,CTO MBs electrode delivers better cycling performance and rate performance under the same test conditions.The reason for the excellent performance is that the microbars have a larger pore volume and specific surface area than CTO NPs.On the one hand,its porous structure and large specific surface area can increase the contact area between electrode materials and electrolyte,which can alleviate large volume changes and provide more active sites during the charge-discharge process.On the other hand,one-dimensional porous structure can accelerate electron transfer and promote Li⁺diffusion,and thus improving conductivity of electrode materials.(2)NiTiO₃nanoparticles(NTO NPs)and NiTiO₃microbars(NTO MBs)were synthesized using a facile solvothermal method.The effects of microstructure on electrochemical properties were investigated.Due to the synergetic effect of porous bar-like structure and high surface area,the NTO MBs electrode exhibits higher capacity and better cycling performance than NTO NPs electrode under the same test conditions.The excellent electrochemical properties of the NTO MBs electrode are attributed to the improved electronic conductivity and porous structure,whereby fast charge transfer and facile diffusion of the Li-ions to the active sites are enabled.(3)Fe₂TiO₅nanoparticles(FTO NPs)/reduced graphene oxide(r GO)composites with network structure were prepared through self-assembly on the surface of graphene oxide(GO)by attachment of FTO NPs.As an anode material for LIBs,its electrochemical performances were tested.Compared to pure FTO NPs electrode,FTO NPs/r GO electrode shows better cycling stability and rate performance.The excellent properties are mainly due to the synergistic effect of FTO NPs and r GO.r GO can decrease the agglomeration of FTO NPs,and FTO NPs can effectively reduce the stacking of adjacent r GO.This composite structure design can provide sufficient buffer space to alleviate volume expansion.In addition,the r GO possesses good electrical conductivity,which can accelerate the transfer of electrons and ions after recombination with FTO NPs,thus reducing the total resistance of the battery.