Preparation Of Lithium Titanate Anode Material By Spray Drying Method And Its Electrochemical Performance

Rising oil prices and global warming have made it more important to develop energy-saving and environment-friendly automobile products.As a new generation of rechargeable power source,lithium ion battery is popular in the new energy industry,and has the advantages of high energy density,high working voltage,good cycle life and no memory effect.At present,the cathode material of lithium ion battery used in the market mostly uses graphite material.However,as a negative electrode of lithium ion battery,graphite has some disadvantages such as poor multiplier performance,poor cycle life and poor safety performance.Therefore,it is particularly important to search for anode materials with high capacity and good safety performance.Lithium titanate is known as a"zero strain"material with good cyclic stability.Theoretical capacity is 175 m Ah/g.Lithium titanate can be used as a substitute for graphite cathode due to its advantages such as small size,light weight,no memory effect,high diffusion coefficient and good safety performance.Li₄Ti₅O₁₂prepared by solid phase method is prone to heterophase segregation and is prone to generate heterophases such as Ti O₂and Li₂Ti O₃.And Li₄Ti₅O₁₂has poor conductivity and low capacity.In this regard,we come up with two solutions:(1)Use spray drying method instead of solid phase method to solve the problems of element segregation and heterophase;(2)Use metal sulfide as semiconductor load.Cu₂S is a semiconductor with good conductivity in metal sulfide,which solves the problem of poor conductivity of Li₄Ti₅O₁₂.Secondly,since Cu₂S is a material with higher specific capacity,the capacity of the material can be improved after loading Cu₂S.The main contents are as follows:(1)Spherical lithium titanate was prepared by spray drying-solid calcination.At the same time,the effects of different molar ratios of lithium-titanium and calcination temperature on the morphology and composition of spherical lithium titanate,and its electrochemical properties as electrode materials for lithium ion batteries were studied in detail.XRD,SEM,constant current charge and discharge tests show that when the molar ratio of lithium to titanium is 0.816 and the calcination temperature is 800?,the synthesized Li₄Ti₅O₁₂has a uniform particle size distribution and no impurity phase.At a 1 C rate,the specific discharge capacity at the first cycle was 185.1 m Ah/g.After 100 cycles,the specific discharge capacity was 169.7 m Ah/g,and the capacity retention rate was 91.7%.At 1 C,2 C,5 C,and 10 C rates,the first-cycle discharge specific capacities were 181.7 m Ah/g,160.7 m Ah/g,139 m Ah/g,and 109 m Ah/g.It shows that the material has better cycle stability and rate performance.(2)The conductivity of Li₄Ti₅O₁₂is poor,and the theoretical capacity is not high.In order to improve the electrochemical performance of Li₄Ti₅O₁₂materials,we used a better conductivity Cu₂S and Li₄Ti₅O₁₂composite to improve the conductivity and conductivity of Li₄Ti₅O₁₂.Through copper mirror reaction,Cu is deposited on Li₄Ti₅O₁₂,and Cu₂S/Li₄Ti₅O₁₂composite material is formed after sulfur powder vulcanization.After conducting XRD,SEM,constant current charge and discharge tests,the results show that in the ether electrolyte,the first cycle discharge specific capacity is 206.4 m A h/g,and after 30 cycles,the discharge specific capacity is 187.8m A h/g,the capacity retention rate is 91%.At a 10 C rate,the capacity retention rate is98.5%after 100 cycles.At a rate of 0.5 C,the specific discharge capacity is 239 m A h/g.When the charge and discharge rate is increased from 0.5 C to 10 C,and then restored to 0.5 C,the discharge specific capacity can be quickly restored to 220 m A h/g.It shows that the composite material has higher capacity,better cycle stability and better rate.The excellent electrochemical performance may be the result of the synergistic effect of Cu₂S and Li₄Ti₅O₁₂.