Study On The Preparation And Modification Of Lithium Titanate Battery Materials By Solid Phase Method

In recent years,with the adjustment of national industrial structure and energy structure,efforts to develop and efficiently utilize renewable clean green energy have become the main direction of energy development.Lithium-ion batteries as an efficient,convenient and green energy storage device,are widely used in daily life and production.With the growth of demand for consumer electronic products,the popularization and popularization of electric vehicles,and the promotion and development of energy storage industry,the performance requirements of lithium-ion batteries are getting higher and higher.Lithium titanate(Li₄Ti₅O₁₂,abbreviated as LTO)is a promising negative material for lithium ion batteries because of its high safety,long life and high efficiency compared with carbon anode materials.The preparation and properties of LTO have attracted extensive attention of researchers.（1）Preparation and properties of Li₄Ti₅O₁₂ by solid-phase method.Li₄Ti₅O₁₂ was prepared by solid-phase method with titanium dioxide（titanium dioxide）and lithium carbonate（Li₂CO₃）as main raw materials.The effects of material ratio(n（Li/Ti）,calcination time（t）and calcination temperature（T）on the properties of Li₄Ti₅O₁₂ were investigated.The optimum technological conditions were obtained as follows:n（Li/Ti）=0.85,t=12h,T=800 C.The specific capacity of the prepared Li₄Ti₅O₁₂ at 0.2C ratio was 148.30 mAh·g^-1,and the retention rate of 100 continuous charge-discharge cycles at 0.2C ratio was as high as 96.13%.The prepared Li₄Ti₅O₁₂ has good cycle performance.（2）Preparation and properties of lithium titanate/graphene（LTO-GO）composites.Graphite oxide was prepared by redox method with graphite,concentrated sulfuric acid,concentrated phosphoric acid,potassium permanganate and hydrogen peroxide as main raw materials.Lithium titanate/graphene（LTO-GO）composites were prepared by mixing Li₄Ti₅O₁₂ with graphene oxide solution at a certain mass ratio in liquid phase.When the mass ratio of Li₄Ti₅O₁₂ to graphene oxide is 95:5,the specific capacity of the material is 186.10 mAh·g^-1 at 0.2C ratio,and the retention rate of 100 continuous charge-discharge cycles is 97.17%at 0.2C ratio.The material has good cycle performance.（3）Preparation and properties of Li_4-x-x Cu_xTi₅O₁₂ composites.Li_4-xCu_xTi₅O₁₂ composites were prepared by solid-phase method using titanium dioxide,Li₂CO₃ and Cu（NO₃）₂ as main raw materials and homogeneous mixing in a certain proportion.Li_3.8Cu_0.2Ti₅O₁₂ was prepared when x=0.20.The specific capacity of Li_3.8Cu_0.2Ti₅O₁₂ at 0.2C ratio was 173.30 mAh·g^-1,and the retention rate of 100 continuous charge-discharge cycle was 96.64%.It had good cycle performance.