Research On Synthesis And Electrochemical Performance Of NiTiO₃ And CoTiO₃

In recent years,titanium-based transition metal oxides have occupied a place in the research and development of lithium-ion batteries anode materials.Prior to this,it was mainly used in catalysts,sensors and so on.It is found that titanium-based transition metal oxides have higher theoretical specific capacity than carbon materials,better stability than titanium-based materials,and have the advantages of small volume change of titanium-based materials.At present,the reported titanium-based transition metal oxide material morphology is relatively simple,to achieve a special morphology needs more complex methods.However,the special morphology can endow the material with higher electrochemical performance.In order to solve this problem,nickel titanate and cobalt titanate materials with different morphology were prepared by solvothermal method and sol-precipitation method respectively,and their electrochemical properties were tested as anode materials for lithium-ion batteries.The micro-mesoporous nano-flower NiTiO₃ was prepared by adjusting the ratio of mixed solvent in the solvothermal process,and the growth of nano-flower was observed by SEM images with the increase of glycerol in the mixed solvent.The optimal reaction conditions were obtained by adjusting the preparation process.The existence of micro-mesoporous provides higher charge transfer rate and Li-ion diffusion rate,which is conducive to the formation of lithium ions fast channels,Moreover,the high specific surface area of the nano-flowers provides more locations for the insertion/extraction of Li⁺.As an anode material for lithium-ion batteries,nano-flower NiTiO₃ shows excellent cycle stability.The flocculent CoTiO₃ with high specific surface area was successfully synthesized by solvothermal method,As an anode material of lithium-ion battery,the high cycling performance of CoTiO₃ is due to its large specific surface area,which makes Li⁺have more positions in the process of insertion/extraction:After the initial 10 cycles of activation,the capacity retention rate is up to 97.73%,and the rate capability is favorable.Carbon nanotube composites were used to improve the electrochemical properties of the materials:The coulomb efficiency of the first cycle of NiTiO₃ and CoTiO₃ increased by 9.18%and 82.8 m Ah g^-1,respectively,and the capacity retention rate increases.The electrochemical impedance both before and after the cycle decreases obviously.The composite of carbon nanotubes makes the material structure more stable,the capacity retention is better,the electrical conductivity is improved,the cycling performance is improved.Spherical NiTiO₃ and porous spherical CoTiO₃ were prepared by sol-precipitation method,and flake graphite composite NiTiO₃ was used.The excellent cycling performance of the material indicates that the porous property is beneficial to increase the contact area between the electrode and the electrolyte,and the spherical structure has a strong ability to adapt to the volume change and maintain the stability of the structure in the process of charge and discharge.The composite flake graphite can improve the initial coulomb efficiency,the cycling performance,and the electronic conductivity of the material,reduce the polarization of the battery,which is beneficial to the industrial application of NiTiO₃ lithium-ion battery anode materials.