Study On Preparation And Electrochemical Performance Of Modified Li₄Ti₅O₁₂ As Anode Materials For Lithium-ion Batteries

Spinel Li4Ti5O12is a new valuable anode material for lithium ion battery inmarket with the very good cycle stability, but the actual application of Li4Ti5O12ishindered because of the poor electronic and ionic conductivity, poor rate capabilityand attenuation of lithium ion battery capacity is quick high rate discharge condition.It is essential to improve the rate performance for the commercialization of Li4Ti5O12by the modification. Aiming at these problems, uniform nanoparticles of spinellithium titanate were synthesised by different preparation methods and coatingtechnology, and their structures, morphology and electrochemical properties werestudied systemly.1. spinel Li4Ti5O12were prepared by hydrothermal method, coprecipitationmethod and solid phase reaction method. And The as-prepared samples were testedby by X-ray diffraction， transmission electron microscopy and electrochemicalperformance test. The results show that the Li4Ti5O12sample has uniform distributionand the smaller size which prepared by coprecipitation method and solid phasereaction method, but there is some impurities of anatase titanium dioxide by preparedby hydrothermal method. The first discharge capacity was185.8mAh g-1at1C bythe coprecipitation method, and the discharge capacity was166.8mAh g-1after80cycle at1C.2. Li4Ti5O12@V2O5were synthesized by a "one-pot" coprecipitation method. Thestructure and morphology of the as-prepared materials were analyzed by X-raydiffraction and transmission electron microscopy. The results show that V2O5issuccessfully coated on the Li4Ti5O12. Electrochemical testing showed that theLi4Ti5O12@V2O5samples (V2O5=0.02) keep at a high discharge capacity of169.9mAh g-1after150cycles at1C. The existence of the V2O5not only enhanced electricconductivity, but also enhances reversible capacity and cyclic performance of theLi4Ti5O12. 3. Spinel Li4Ti5O12anode material and Li4Ti5O12/LiV3O8composites synthesizedby a coprecipitation method. The structure and morphology of the as-preparedmaterials were analyzed by X-ray diffraction and transmission electron microscopy.The results show that V2O5is successfully coated on the Li4Ti5O12. Li4Ti5O12/LiV3O8composite material has better electrochemical performance than pure spinel lithiumtitanate. As a result, the as-prepared product exhibits capacity as high as70mAh g-1at10C, which is better than pure spinel lithium titanate with large ratio of charge anddischarge performance. The spinel lithium titanate compound still show a goodelectrochemical performance that the discharge capacity was140.3mAh g-1after50cycle at3C.