Silicon or silicon oxide@titanium oxide core-shell structure composite material and preparation thereof

A composite material, titanium oxide technology, used in structural parts, electrochemical generators, electrical components, etc., can solve the effect of inhibiting the expansion of internal active substances, difficult to guarantee coating uniformity, and inability to guarantee powder uniformity, etc. problems, to achieve the effect of good roasting consistency, high crystallinity, and improved electrical conductivity and ion conductivity

Active Publication Date: 2019-06-21
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the existing methods have the following problems: 1) the coating conditions are relatively harsh, requiring high temperature and high pressure environment guarantees, and at the same time need to be treated with strong corrosive substances such as strong acids and alkalis; 2) coating uniformity is difficult to ensure, which will affect the The inhibitory effect of the expansion of the internal active material affects the cycle performance; 3) Using a fixed bed high temperature roasting crystallization, the uniformity cannot be guaranteed when processing a large amount of powder

Method used

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  • Silicon or silicon oxide@titanium oxide core-shell structure composite material and preparation thereof
  • Silicon or silicon oxide@titanium oxide core-shell structure composite material and preparation thereof
  • Silicon or silicon oxide@titanium oxide core-shell structure composite material and preparation thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0064] At room temperature, a certain amount of high-purity SiO x The powder is mixed with hydroxymethyl cellulose at a mass ratio of 5:1 to obtain a mixed powder, and ethanol and water are mixed at an alcohol-water volume ratio of 200:1 as a dispersion solution and the mixed powder is added to the mixer at a stirring speed of 500r / min. Then tetrabutyl titanate TBOT and ethanol were mixed at a volume ratio of 1:5 to prepare a precursor solution, and then the precursor solution was slowly injected into the stirrer through an injection device at a speed of 5 μL / min. After the injection, heat to the reaction temperature of 80°C for coating reaction, the reaction time is 100min, and the intermediate product is obtained after suction filtration. The intermediate product was put into a fluidized bed, Ar gas was introduced at a gas velocity of 100ml / min, and roasted at 800°C for 8h to obtain the final product.

[0065] Electrochemical performance test:

[0066] At room temperature,...

Embodiment 2

[0070] At room temperature, mix a certain amount of high-purity Si powder with hydroxypropyl cellulose at a mass ratio of 10:1, and mix ethanol and water at a volume ratio of 500:1 as a dispersion solution and add the mixed powder to the mixer. The stirring speed is 1000r / min. Then tetraisopropyl titanate and isopropanol were mixed at a volume ratio of 1:10 to prepare a precursor solution, which was added to the injection device and slowly injected into the stirrer at an injection speed of 10 μL / min. After the injection, heat to the reaction temperature of 95° C. for coating reaction, the reaction time is 60 minutes, and the intermediate product is obtained after suction filtration. Put the intermediate product in a fluidized bed, flow Ar gas at a gas velocity of 200ml / min, and roast at 1000°C for 6h to obtain the final product.

Embodiment 3

[0072] At room temperature, a certain amount of high-purity SiO x The powder is mixed with hydroxypropyl cellulose at a mass ratio of 2:1, and ethanol and water are mixed at an alcohol-water volume ratio of 100:1 as a dispersion solution and the mixed powder is added to the mixer at a stirring speed of 100r / min. Then tetrabutyl titanate TBOT and isopropanol were mixed at a volume ratio of 1:1 to prepare a precursor solution, which was added to the injection device and slowly injected into the stirrer at an injection speed of 1 μL / min. After the injection, heat to the reaction temperature of 60°C to carry out the coating reaction, the reaction time is 180min, and the intermediate product is obtained after suction filtration. The intermediate product was placed in a fluidized bed, Ar gas was introduced at a gas velocity of 10ml / min, and roasted at 600°C for 12h to obtain the final product.

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Abstract

The invention discloses a silicon or silicon oxide@titanium oxide core-shell structure composite material, and belongs to the technical field of lithium ion battery negative electrode materials. The composite material is a core-shell double-layer structure, the inner layer contains silicon or silicon oxide(SiOx), and the outer layer contains titanium oxide and densely and evenly wraps the inner layer. The invention also discloses a preparation method of the composite material. The preparation method includes the following steps of: adding powder containing silicon or silicon oxide and a surfactant into a reactor, mixing with a dispersion solution, adding a precursor solution into the mixture, heating to a coating reaction temperature for coating reaction, and obtaining an intermediate product; and roasting the intermediate product under the protection of an inert atmosphere to obtain the composite material. The composite material has the characteristics of easy dispersibility, high Sicontent, significantly-improved conductivity, high specific capacity and good cycle stability. The preparation method is simple in process, has no pollution, is low in cost and short in procedure, andis easy to realize batch production.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery negative electrode materials, in particular to a silicon or its oxide@titanium oxide core-shell structure composite material and a preparation method, which can be used for lithium-ion battery negative electrode materials. Background technique [0002] As one of the most potential anode materials for next-generation lithium-ion batteries, silicon has the characteristics of high reserves, low cost, and the highest theoretical specific capacity (4200mAh / g). For silicon-based anode materials, the main challenge is that its high volume expansion rate (400%) in the electrochemical reaction will cause specific damage to the overall structure, resulting in rapid capacity decay. At the same time, whether it is pure Si or its oxide SiO x , its own extremely low conductivity also seriously affects the electrochemical performance. [0003] The report of using the coating layer to prepare the co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/485H01M4/48H01M10/0525
CPCY02E60/10
Inventor 肖哲熙魏飞于春辉林贤清
Owner TSINGHUA UNIV
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