The Study Of Preparetion And Ion Change Performance Of Doped Lithium Titanium Composite Oxide

Lithium and its compounds are widely used in various industries with their excellent properties.Among them,the lithium battery industry has been received widely attention as clean energy in recent years.Therefore,how to efficiently obtain lithium resources has become a key factor in the development of lithium applications.As we all know,lithium mainly exists in the form of liquid lithium and ore lithium.The mining of ore lithium will cause irreversible damage to the environment,and the liquid lithium resource has become a research hotspot because of the development of lithium extraction technology and its huge reserving capacity as well as the eco-friendly lithium extraction technology.In this paper,high-efficiency lithium ion sieves were successfully synthesized during the background of liquid lithium extraction technology,and its synthetic route and performance were further investigated.Firstly,the Li₄Ti₅O₁₂ doped Ce was prepared by a solvothermal method and then this oxide sample was used to fabricate lithium ion-sieve（L-IE）by acid leaching.The crystal phase,morphology and selective stability of ion sieves were characterized by TG-DTG,XRD and SEM techniques.The results show:when the doping of Ce is 0.02,the lithium ion-sieve has the best selectivity and adsorbability.XRD results show that the characteristic peak shift appears after the doping of cerium ions,but the basic spinel structure remained,no matter before or after acid modification.The saturated Li⁺exchange capacity of the IE-H was up to 6.8506mmol/g,and remained high after 5 cycles of Li⁺extraction test,indicating the high exchange capacity and stability of the prepared ion-sieve.Secondlly,the Li₄Ti₅O₁₂ samples with addition of F127 were also prepared by a solvothermal method.After leaching with 0.1mol/L HCl solutions,these samples transformed into lithium ion-sieves（IE-H）.The crystal phase,morphology and selective stability of ion sieves were characterized by TG-DTG,XRD and SEM techniques.Moreover,the adsorption performance of ion sieves was tested.The results show that with the addition,the ion sieves calcined at 800℃ not only have a unique morphology which looks like a spherical stack but also have a spinel structure with a relatively pure crystal phase and uniform particle sizes.The acid modification rate after immersion in hydrochloric acid is 88.60%,and the crystal form and surface particle morphology remain unchanged before and after acid modification.The saturated Li⁺exchange capacity of the IE-H was up to 6.6480mmol/g,and remained at 6.6324 mmol/g after 5 cycles of Li⁺extraction test.Besides,the IE-H has high adsorption capacity for Li⁺in single ion solution and mixed ion solution,suggesting the high exchange capacity and stability of the prepared ion-sieve.Finally,high temperature solid state method was used to synthesize doped lithium titanium composite oxides（LTCO）by grinding self-preparation titanium hydroxide,lithium acetate and a few amount acetate and calcination process.After pickling process by 0.1mol/L hydrochloric acid solution,LTCO transformed to the lithium ion sieve.After characterizing samples with different calcination temperatures,it was found that the ion sieve calcined at 750℃ had a spinel structure,high characteristic peak strength,and the lowest content of impurities such as titanium dioxide.And the surface morphology of the sample calcined at 750℃ is more regular and the pores are well developed.After selective and cyclic adsorption performance tests on the 750℃ sample,it was found that the saturation adsorption capacity of the ion sieve was 4.4374 mmol/g,which was smaller than that of the ion sieve prepared by hydrothermal synthesis,and the ion sieve has excellent stability and selective adsorption capacity for Li⁺adsorption.After 5 cycles,the adsorption performance of ion sieve for lithium ions is 4.3652mmol/g.