Composite coated modified nanosilicon material, and preparation method and application thereof

Abstract

The application relates to a composite coated modified nanometer silicon material and a preparation method and application thereof, characterized by comprising the following raw material components in a mass ratio: nanometer silicon powder: dopamine hydrochloride (DA-HCl): silane coupling agent (SCA): polycarbomethylsilane (PCS) = 20:10:(1-2):10, wherein the nanometer silicon powder is nanometer silicon powder with a particle size of 50-300 nm. The composite coated modified nanometer silicon material has the advantages of hydrophobicity, good oxidation resistance, high chemical stability, simple preparation method and easy operation. The composite coated modified nanometer silicon material has the advantages of good stability, long service life and the like as a battery negative electrode material.

Description

Technical Field

[0001] This invention relates to the field of energy storage materials, and in particular to a composite coated modified nano-silicon material, its preparation method, and its application. Background Technology

[0002] The rapid popularization of new energy vehicles has placed higher demands on the electrode materials of lithium-ion batteries. Traditional carbon (specific capacity ~372mAh / g) anode materials can no longer meet the requirements and will be replaced by high-capacity alloy silicon, metallic lithium, and other anodes. Among them, silicon has a specific capacity as high as 4200mAh / g, showing great potential. Domestic companies such as CATL and BYD, as well as international groups such as Samsung and Panasonic, have successively invested heavily in the industrialization of silicon anode lithium batteries.

[0003] The most serious problem with silicon anodes is that the huge volume effect (~400%) easily causes the anode structure to collapse. The solution is to nanoscale silicon. However, nano-silicon (nanoSi) has a large specific surface area and surface energy, making it easily oxidized by media such as water and oxygen, and contaminated by other impurities. The large amount of SiO2 and other impurities formed will cause a sharp decline in specific capacity and material lifetime. Therefore, while retaining the structural characteristics of nanoSi, improving its stability through a series of measures, such as hydrophobicity and oxidation resistance, is of great significance for the preparation of high-performance silicon anodes and silicon-based optoelectronic materials. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a composite coated modified nano-silicon material with good hydrophobicity, good antioxidant properties, high chemical stability and non-agglomeration, as well as its preparation method and application.

[0005] To solve the above technical problems, the present invention adopts the following technical solution: a composite coated modified nano-silicon material, characterized in that it is composed of raw material components in the following mass ratio: nano-silicon powder: dopamine hydrochloride (DA-HCl): silane coupling agent (SCA): polycarboxymethylsilane (PCS) = 20:10:(1~2):10, wherein the nano-silicon powder is nano-silicon powder with a particle size of 50~300nm.

[0006] This invention also provides a method for preparing composite-coated modified nano-silicon materials, characterized by the following steps:

[0007] A. Weigh an appropriate amount of dopamine hydrochloride and dissolve it in an appropriate amount of methanol to prepare a dopamine methanol solution with a dopamine hydrochloride mass concentration of 6.0%; add nano-silicon powder to the prepared dopamine methanol solution at a material-to-liquid ratio of 1g:10mL, and sonicate thoroughly to obtain a suspension.

[0008] B. Weigh an appropriate amount of polycarbomethylsilane and dissolve it in an appropriate amount of xylene to prepare a polycarbomethylsilane xylene solution with a polycarbomethylsilane mass concentration of 30.0%. Then weigh an appropriate amount of silane coupling agent and add it to the polycarbomethylsilane xylene solution to obtain a premixed solution with a silane coupling agent mass concentration of 6.0%.

[0009] C. Mix the suspension obtained in step A with the premixed solution obtained in step B at a volume ratio of 7:1, then stir slowly and heat to 40-50°C until homogeneous. Centrifuge at 3000 r / min for 5 min, and dry the solid material to obtain the composite coated modified nano-silicon material.

[0010] This invention also provides a simplified method for preparing composite-coated modified nano-silicon materials, characterized by the following steps:

[0011] A. Weigh an appropriate amount of dopamine hydrochloride and dissolve it in an appropriate amount of methanol to prepare a dopamine methanol solution with a dopamine hydrochloride mass concentration of 6.0%; add nano-silicon powder to the prepared dopamine methanol solution at a material-to-liquid ratio of 1g:10mL, and sonicate thoroughly to obtain a suspension.

[0012] B. Weigh an appropriate amount of polycarbonylmethylsilane and dissolve it in an appropriate amount of xylene to prepare a xylene solution with a polycarbonylmethylsilane mass concentration of 30.0%. Then, add the suspension obtained in step A directly according to the mass ratio of polycarbonylmethylsilane to nano-silicon powder of 1-2:20. After heating to 50°C, quickly add the silane coupling agent dropwise, stir thoroughly and evenly, and then centrifuge at 3000 r / min for 5 min. After drying the solid material, the composite coated modified nano-silicon material is obtained. The mass ratio of the silane coupling agent to the nano-silicon powder is 1:2.

[0013] Both preparation methods can produce composite coated modified nano-silicon materials, but the simpler and more convenient method produces a thicker coating with some agglomeration, resulting in a product with performance inferior to the other preparation method of this invention.

[0014] The silane coupling agent is γ-aminopropyltriethoxysilane (KH-550), N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), 3-(phenylamino)propyltrimethoxysilane (KBM-573), aminopolyethylene glycol triethoxysilane (NH2-PEG-Silane), or any mass ratio of the four thereof.

[0015] The inner layer of the composite-coated modified nano-silicon material obtained in this invention is coated with dopamine, and the outer layer is coated with polycarbonyl methylsilane. A silane coupling agent links the nano-silicon and the polycarbonyl methylsilane layer.

[0016] The composite-coated modified nano-silicon material is used as a negative electrode material for lithium batteries.

[0017] This invention, while maintaining the size of nano-silicon particles, can reduce their surface energy and isolate them from moisture in the air, effectively preventing their aggregation and oxidation, and enhancing the stability of their structure and performance.

[0018] The composite-coated modified nano-silicon material obtained by this invention has the advantages of good hydrophobicity, good antioxidant properties, and high chemical stability, and the preparation method is simple and easy to operate. As a battery anode material, the composite-coated modified nano-silicon material has advantages such as good stability and long service life. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the microstructure of the composite-coated modified nano-silicon material of the present invention.

[0020] Figure 2 The image shows a scanning electron microscope (SEM) image of the composite-coated modified nano-silicon material described in Example 1.

[0021] Figure 3 The image shows a scanning electron microscope (SEM) image of the composite-coated modified nano-silicon material described in Example 2.

[0022] Figure 4 This is a scanning electron microscope (SEM) image of the composite-coated modified nano-silicon material described in Example 3.

[0023] Remark: Figure 1 The ingredients are 1-nano silicon, 2-polydopamine, 3-silane coupling agent, and 4-polycarboxymethylsilane. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Example 1: A method for preparing composite-coated modified nano-silicon materials, characterized by the following steps:

[0026] A. Dissolve 5.0g DA-HCl in 100mL methanol and stir evenly to obtain a solution; then add 10.0g nanoSi to this solution and sonicate for 30min to obtain a pretreated nanoSi suspension.

[0027] B. Dissolve 5.0g PCS in 15mL xylene, then add 1.0g SCA and stir to obtain a PCS-SCA mixed solution;

[0028] C. Heat the PCS-SCA mixed solution to 50℃, and add nanoSi suspension dropwise to the PCS-SCA mixed solution. Stir the mixture thoroughly for 4 hours to obtain a reaction solution. Finally, centrifuge the reaction solution at 3000 r / min for 5 minutes to obtain a solid substance. Dry the obtained substance at 60℃ for 12 hours to obtain a composite coated modified nano-silicon material.

[0029] like Figure 2 As shown, the obtained composite-coated modified nano-silicon material has uniform particle size and no agglomeration.

[0030] Example 2: A method for preparing composite-coated modified nano-silicon materials, characterized by the following steps:

[0031] A. Dissolve 5.0g DA-HCl in 100mL methanol and stir evenly to obtain a solution; then add 10.0g nanoSi to this solution under a nitrogen atmosphere, and sonicate for 1h to obtain a suspension of pretreated nanoSi.

[0032] B. Dissolve 5.0g of PCS in 15mL of xylene, then add 0.5g of SCA and stir to obtain a PCS-SCA mixed solution;

[0033] C. Heat the PCS-SCA mixed solution to 50℃, and add the nanoSi suspension dropwise to the PCS-SCA solution at a rate of 20 mL / min under a nitrogen atmosphere. Stir the mixture thoroughly for 6 h to obtain the reaction solution. Finally, centrifuge the obtained reaction solution at 5000 r / min for 10 min, and dry it at 60℃ for 24 h to obtain the composite coated modified nano-silicon material.

[0034] like Figure 2 As shown, the obtained composite-coated modified nano-silicon material has uniform particle size, a very thin coating layer, and no agglomeration.

[0035] Example 3: A method for preparing composite-coated modified nano-silicon materials, characterized by the following steps:

[0036] A. Dissolve 5.0g DA-HCl in 100mL methanol and stir evenly to obtain a solution; then add 10.0g nanoSi to this solution under a nitrogen atmosphere, and sonicate for 30min to obtain a suspension of pretreated nanoSi.

[0037] B. Dissolve 5.0 g of PCS in 15 mL of xylene; then, directly mix the PCS solution with the nanoSi suspension, heat to 50 °C and add 1.0 g of SCA dropwise, stir thoroughly for 4 h to obtain a mixture; finally, centrifuge the above mixture at 4000 r / min for 8 min, and dry at 60 °C for 12 h to obtain the composite coated modified nano-silicon material.

[0038] like Figure 4 As shown, the obtained composite coated modified nano-silicon material has a thicker coating layer and exhibits some agglomeration, and its dispersibility is not as good as the products obtained in Examples 1 and 2.

Claims

1. A composite-coated modified nano-silicon material, characterized in that: The raw material components are composed of the following mass ratio Composition: Nano-silicon powder: Dopamine hydrochloride: Silane coupling agent: Polycarbomethylsilane = 20: 10: 1-2: 10, wherein the nano-silicon powder has a particle size of 50-300 nm, and the composite coated modified nano-silicon material is prepared by the following method: A. Weigh an appropriate amount of dopamine hydrochloride and dissolve it in an appropriate amount of methanol to prepare a dopamine methanol solution with a dopamine hydrochloride mass concentration of 6.0%; add nano-silicon powder to the prepared dopamine methanol solution at a material-to-liquid ratio of 1 g: 10 mL, and sonicate thoroughly to obtain a suspension. B. Weigh an appropriate amount of polycarbomethylsilane and dissolve it in an appropriate amount of xylene to prepare a xylene solution with a polycarbomethylsilane mass concentration of 30.0%. Then weigh an appropriate amount of silane coupling agent and add it to the polycarbomethylsilane xylene solution to obtain a premixed solution with a silane coupling agent mass concentration of 3.0~6.0%. C. Mix the suspension obtained in step A with the premixed solution obtained in step B at a volume ratio of 7:1, then stir slowly and heat to 40-50℃, stir evenly, then centrifuge at 3000 r / min for 5 min, take the solid material and dry it to obtain the composite coated modified nano-silicon material.

2. The composite-coated modified nano-silicon material according to claim 1, characterized in that: The silane coupling agent is one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, 3-(phenylamino)propyltrimethoxysilane, aminopolyethylene glycol triethoxysilane, or a mixture thereof in any mass ratio.

3. A composite-coated modified nano-silicon material, characterized in that: The material is composed of raw materials in the following mass ratio: nano-silicon powder: dopamine hydrochloride: silane coupling agent: polycarbomethylsilane = 20: 10: 1-2: 10, wherein the nano-silicon powder has a particle size of 50-300 nm, and the composite coated modified nano-silicon material is prepared by the following method: A. Weigh an appropriate amount of dopamine hydrochloride and dissolve it in an appropriate amount of methanol to prepare a dopamine methanol solution with a dopamine hydrochloride mass concentration of 6.0%; add nano-silicon powder to the prepared dopamine methanol solution at a material-to-liquid ratio of 1 g: 10 mL, and sonicate thoroughly to obtain a suspension. B. Weigh an appropriate amount of polycarbonylmethylsilane and dissolve it in an appropriate amount of xylene to prepare a xylene solution with a polycarbonylmethylsilane mass concentration of 30.0%. Then, add the suspension obtained in step A directly according to the mass ratio of polycarbonylmethylsilane to nano-silicon powder of 1-2:

20. After heating to 50°C, quickly add the silane coupling agent dropwise, stir thoroughly and evenly, and then centrifuge at 3000 r / min for 5 min. After drying the solid material, the composite coated modified nano-silicon material is obtained. The mass ratio of the silane coupling agent to the nano-silicon powder is 1:

2.

4. The composite-coated modified nano-silicon material according to claim 3, characterized in that: The silane coupling agent is one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, 3-(phenylamino)propyltrimethoxysilane, aminopolyethylene glycol triethoxysilane, or a mixture thereof in any mass ratio.

5. The application of the composite-coated modified nano-silicon material as described in claim 1 or 3 as a negative electrode material for lithium-ion batteries.

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