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Preparation and Modification Study of Li4Ti5O12 as an Anode Material for Lithium Ion Batteries

Author: TianBingBing
Tutor: WangHaiHui
School: South China University of Technology
Course: Chemical Engineering
Keywords: Lithium ion battery Anode material Spinel Li4Ti5O12 Metal cation doping Graphene coating
CLC: TM912
Type: Master's thesis
Year: 2011
Downloads: 281
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Abstract


Graphite carbon anode materials for lithium-ion batteries are widely used in irreversible loss of capacity, and there is a security problem. Spinel Li 4 Ti 5 O 12 has excellent safety performance as a lithium-ion battery anode material preparation process simple, inexpensive cost and environmental characteristics, and in the process of charging and discharging structure almost no change is called a \In, Li 4 Ti 5 O 12 materials low electronic conductivity and ion conductivity (intrinsic conductivity of only 10 -9 Scm -1 ) affect the electrochemical properties of the electrochemical performance, especially under high magnification, become the biggest obstacle to its industrial application. This paper aims to Nb-doped graphene coating technology ways to improve its conductivity and thus improve the electrochemical performance. To further tap the spinel Li 4 Ti 5 of O 12 reversible capacity and rate capability, the paper also studied in the low potential The electrochemical behavior and conductive agent on the electrochemical behavior of the material. The first chapter of a lithium-ion battery anode material progress and spinel of Li 4 Ti 5 O 12 anode material the status quo, the significance of the topic of this paper, and the need to solve scientific problems. Chapter II briefly introduces the Preparation of Spinel Li 4 Ti 5 O 12 and its chemical modified sample process medicines, instruments and characterization methods used in the process of laboratory instruments and test battery. Chapter acetate sol-gel prepared spinel Li 4 Ti 5 O 12 and a series of niobium-doped Li 4 Ti 5 O 12 , different doping amount of Li 4 Ti 5 O 12 electrochemical performance, in-depth study of the electrochemical properties of the material when the best doping amount. The results show that the Nb 5 partial substitution of Ti 4 , the resulting material is improved conductivity, the charge and discharge capacity has increased, the cycle performance has been greatly improved. The the Act synthetic Li Ti 4.95 Nb 0.05 O 12 materials cycle voltammograms with higher redox peak symmetry than Li 4 Ti 5 O 12 good having a good cycle performance. Assembled into the test cell electrochemical impedance results and conductivity test results show the Li4Ti4.95Nb0.05O12 material has than of Li 4 the the Ti 5 O 12 Material higher lithium ion conductivity rate and electron conductivity rate. Chapter IV use of citric acid sol - gel synthesis the of Li 4 Ti 5 O 12 and of Li to 4 Ti 4.95 Nb 0.05 O 12 materials, focusing on its depth of discharge behavior, discharge cutoff voltage from 1.0 V extended to 0 V , the reversible capacity of the spinel-type lithium titanate has been improved. This chapter also Li 4 Ti 5 O 12 material depth of discharge behavior of niobium-doped were explored. Tapping the potential to provide a useful reference for the lithium titanate material capacity. The fifth chapter through a simple sol-gel synthesis of graphene coated Li 4 Ti 5 O 12 materials. Take advantage of the special role of the graphene sheets in solution synthesized the of Li 4 Ti 5 O 12 small particles adhere graphene sheets Li 4 Ti 5 O 12 / graphene composite electrode materials. The elemental analysis results show that the composite electrode material a carbon content of approximately 7.8 wt%, XRD analysis showed that the lithium titanate coated with graphene material still showed a single spinel structure. SEM results show that the lithium titanate and graphene have a synergistic effect. The graphene join can prevent Li 4 Ti 5 O 12 reunion, Li 4 Ti 5 O 12 distribution between the graphene sheet layer and a porous structure can also prevent the accumulation of the graphene sheet. Therefore the of Li 4 Ti 5 O 12 / graphene composite electrode materials in Li 4 Ti 5 < / sub> O 12 finer particles. The graphene coated Li 4 Ti 5 O 12 material exhibits good electrochemical performance, especially in large magnification electrochemical properties. Magnification of 10 C, Li 4 Ti 5 O 12 / the graphene composite specific discharge capacity of 100 is 110.3 mAhg -1 , higher than the of Li 4 Ti 5 the O 12 of 84.6 mAhg of -1 . Cyclic voltammetry test results show the of Li Ti 5 the O 12 / graphene composite electrode materials with better electrical conductivity and cycling performance.

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CLC: > Industrial Technology > Electrotechnical > Independent power supply technology (direct power) > Battery
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