Research On Synthesis And Modification Of Lithium Zinc Titanate As Anode Material For Lithium Ion Batteries

Lithium zinc titanate, Li2ZnTi3O8, has attracted significant interests because ofits good cyclinc stability, high specific capacity and low production cost as an anodematerial for lithium ion batteries. However, there is no much attention on thepreparation method and electrochemical behavior of Li2ZnTi3O8. Therefore, thestudies on the preparation method and electrochemical behavior of Li2ZnTi3O8areneeded.The Li2ZnTi3O8samples have been synthesized by high temperature solid-statereaction and sol-gel process, respectively. The effects of synthesized temperature,sintered duration and Li sources on electrochemical properties of Li2ZnTi3O8havebeen studied in this research. In further, the carbon coated and Cu doped Li2ZnTi3O8were prepared using titanate nanowires as a precursor, respectively. And the optimalcontent of carbon coating and Cu-doping were determined by extensive investigation.The results of the simple high temperature solid-state reaction showed that theprue well-crystallized Li2ZnTi3O8can be prepared by sintering the precursor at800oCfor4h. The particle size is about200nm. The changing of the sintering temperaturecan not change the composition of the production. The sample sintered at800oC for4h shows a high initial capacity of232.9mAh/g at a current density of100mA/g, andthere is no obvious capacity decline after30cycles.The sol-gel method has been investigated to prepare Li2ZnTi3O8sample. Theresults indicate that the synthesized temperature, sintered duration, Li sources and theamount of glycol and citric acid will affect the electrochemical property ofLi2ZnTi3O8. And the sample sintered at800oC for3h with a glycol/citric acid rate of2shows the best electrochemical performance. The sample shows a high initialcapacity of230.6mAh/g, with a capacity maintance of99.1%after40cycles. And itshows a capacity of145.2mAh/g after10cycles at a high current density of1000mA/g.The modified Li2ZnTi3O8has been prepared by carbon coating and Cu doping,respectively. And the results show that the carbon coating and Cu doping are botheffective to improve the charge-discharge performance and rate capability ofLi2ZnTi3O8samples. The glucose is used as the carbon source to synthesize the carbon coated Li2ZnTi3O8. The Li2ZnTi3O8sample with10%carbon coated exhibits acapacity of286.9mAh/g after60cycles at a current density of100mA/g. TheLi2Zn0.9Cu0.1Ti3O8shows an initial capacity of244.9mAh/g. The appropriate amountof Cu-doping can decrease electode polarization, enhance reaction activities andlithium ion diffusion.