A preparation method of nano-lithium titanate coated with double high-conductivity materials

Abstract

The invention provides a preparation method of nanometer lithium titanate covered with double highly-conductive materials. Through a sol-gel method, a La[0.5]Sr[0.5]Sc[0.1]Mn[0.9]O3 / C-Li4Ti5O12 anode material is prepared by a step of blending a soluble Li compound and a soluble Ti compound according to a molar ratio of Li / Ti=0.8-1.0, adding into an alcohol-water mixed solvent containing a hydrolysis inhibitor, adding a bi-component chelating agent, subjecting the bi-component chelating agent and metal ions to chelation under alkaline conditions, and stirring and heating to form gel; a step of dissolving a La compound, a Sr compound, a Sc compound and a Mn compound into an alcohol-water mixed solvent according to a molar ratio of La: Sr: Sc: Mn=0.5:0.5:0.1:0.9, adding the bi-component chelating agent, subjecting the bi-component chelating agent and metal ions to chelation under alkaline conditions, and stirring to form sol; a step of mixing the gel and the sol and stirring to form co-gel to obtain a sintering precursor; and a step of ball milling and calcining at 900-1150 DEG C for 5-15 h. The lithium titanate prepared by the method has good dispersion effects and excellent electrochemical performance, and the agglomeration phenomenon of nano-powder is improved significantly.

Description

technical field [0001] The invention relates to a method for preparing lithium titanate, a negative electrode material of a lithium ion secondary battery, in particular to a method for preparing lithium titanate coated with double high-conductivity materials by a sol-gel method. Background technique [0002] As a high specific energy chemical power source, lithium-ion secondary batteries have been widely used in mobile communications, notebook computers, video cameras, cameras, portable instruments and other fields, and have rapidly developed into one of the most important secondary batteries at present. Lithium-ion batteries are favored because of their high voltage, high energy density, long cycle life, and low environmental pollution. At present, most commercial lithium-ion battery anode materials use carbon anode materials, but carbon anode materials have some defects: they react with the electrolyte to form a surface passivation film during the first discharge process, ...

AI Technical Summary

Problems solved by technology

At present, most commercial lithium-ion battery anode materials use carbon anode materials, but carbon anode materials have some defects: they react with the electrolyte to form a surface passivation film during the first discharge process, resulting in the consumption of electrolyte and lower initial Coulombic efficiency. Low; the electrode potential of the carbon electrode is similar to that of metal lithium. When the battery is overcharged, metal lithium may still be precipitated on the surface of the carbon electrode, forming dendrites and causing short circuits, causing safety problems, etc.

Carbon materials have some disadvantages: the presence of lithium dendrites; the first charge and discharge efficiency is relatively low; it interacts with the electrolyte to form a solid electrolyte interface film; there is a relatively obvious voltage hysteresis effect; the preparation method is relatively complicated

Compared with carbon anode materials, alloy-type anode materials generally have higher specific capacity, but poor cycle performance, and alloy-type anode materials also solve some safety problems; recently, spinel-type lithium titanate has been used as a The new type of negative electrode material has the advantages of "zero strain", good cycle performance, good charge and discharge platform, no reaction with electrolyte, cheap price, easy preparation, etc., and has gradually become a research hotspot.

However, Li 4 Ti 5 o 12 The conductivity is very low, almost insulating, and the performance at high magnification is poor. If it is used in power vehicles, large energy storage batteries and other fields, it will be greatly restricted.

Therefore, for Li 4 Ti 5 o 12 Due to the disadvantage of poor electrical conductivity of the material, it is particularly important to improve its electrical conductivity and high-rate performance.

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