Preparation And Electrochemical Performances Of Li₄Ti₅O₁₂ With Unique Morphology For Lithium-ions Battery

As a negative electrode material for lithium-ion batteries(LIBs),spinel lithium titanate has received extensive attention from researchers due to its own cycle stability and remarkable safety performance.Spinel lithium titanate in the charge and discharge process of Li~+in and out,self-structure will not change,known as"zero strain"material.Therefore,it has high safety,and in addition,the spinel lithium titanate has a longer electrochemical charge and discharge platform,and can provide a stable voltage when the electrode is operated.However,it is disadvantageous that the weak electronic conductivity and low Li~+diffusion coefficient of lithium titanate itself severely limit the large-scale commercialization of lithium titanate.Therefore,many researchers have been working on the modification of lithium titanate to improve its electrochemical performance.In this dissertation,lithium titanate samples with excellent electrochemical performance were successfully prepared by modifying the morphology of lithium titanate.The prepared lithium titanate samples were characterized by physical and electrochemical characterization,respectively.It was found that the two shaped lithium titanates have higher reversible capacity and larger rate performance.This topic successfully synthesized a lithium titanate nanosheet with a self-supporting structure with an additional surface lithium storage function.Through physical characterization,the nanosheet has a large specific surface area and a thin thickness.The reversible capacity of the sample can reach 173 mAh/g by electrochemical test under the condition of 0.1 C rate,and the reversible capacity of150 mAh/g can still be achieved even under the condition of 30 C high rate.This is mainly attributed to the self-supporting topography of the sample,which can shorten the lithium ion transport channel and improve lithium ion diffusion performance,thereby significantly improving its own electrochemical performance.In this project,lithium titanate with a positive octahedral topography structure was successfully prepared.After the TEM characterization,the lattice fringe spacing was nm and the[110]crystal plane was determined.This crystal plane determines that the lithium titanate surface has more active sites and can maximize the electrochemical reaction efficiency.Through the charge-discharge test,the reversible capacity of the lithium titanate sample can reach 170 mAh/g at 0.1 C rate.When the current density increases to 30 C high rate,the reversible capacity can still reach 148mAh/g high reversible capacity.In addition,the positive octahedral lithium titanate has good crystallinity,which can effectively reduce the degree of polarization of the sample material.Therefore,this kind of lithium titanate material with a special morphological structure will become a research hotspot for electrode materials of lithium ion batteries in the future.