Preparation And Electrochemical Study On The Ti-based Anode Materials

Li₄Ti₅O₁₂shows poor electronic, so then limits its high rate-capability. In orderto improve the rate performance and reduce the cost of electrode materials,nanostructured materials usually are used to solve the problem, which is thesolid-state diffusion of Li+intercalation and electronic conductivity. However, thetheoretical theory of Li₄Ti₅O₁₂is only175mAh g-1. So to develop a new anodematerial which has a large capacity and high energy density is still a challenge.Compared with simple binary oxides, multicomponent oxides can alter theircompositions and tune effectively the chemical and physical properties, such ascomplex spinel Li₂ZnTi₃O₈, Li₂CoTi₃O₈et al.In here, Li₄Ti₅O₁₂anode materials were successfully prepared by anelectrospinning process. Then the material is characterized by X-ray diffraction（XRD）, scanning electron microscopy （SEM）, transmission electron microscopy（TEM）, thermal gravimetric analysis （TGA）, cyclic voltammetry （CV）, galvanostaticcharge-discharge tests and electrochemical impedance spectroscopy （EIS）. The resultsreveal that the product anealed at700℃show the best morphologies, cycling stabilityand high rate capability. The specific discharge capacity in the first cycle is122mAhg-1at20C, and a specific capacity of120mAh g-1is obtained after300cycles. Thecapacity retentions is98%.Li₂ZnTi₃O₈fibers were successfully prepared by an electrospinning process.Then the material is characterized in detail. The results reveal that a specific dischargecapacity of224mAh g-1is obtained at0.1C after10cycles; this value decreases to190mAh g-1at1.0C, and finally,173mAh g-1at2.0C. Returning after this completedynamic loading cycle to a rate of0.1C for a second time, a specific dischargecapacity of214mAh g-1is obtained, indicating the excellent cycling stability of theLi₂ZnTi₃O₈anode even after rather harsh loading/deloading rates.Li₂CoTi₃O₈fibers were successfully prepared by an electrospinning process,Li₂CoTi₃O₈bulk particles was also synthesized by solid-state reaction. Then thematerials is characterized in detail. For the Li₂CoTi₃O₈fibers, a specific dischargecapacity of142mAh g-1is obtained at a current density of2000mA g-1after30cycles, and a specific capacity of141mAh g-1is obtained after300cycles. Thecapacity retentions is98%. However, the reversible specific discharge capacity of the Li2CoTi3O8bulk particles at the same current density are103mAh g-1after30cycles.