Silver-modified wafer-level silicon nanowire composite negative electrode material for lithium ion battery and integrated preparation method of silver-modified wafer-level silicon nanowire composite negative electrode material

Abstract

The invention provides a silver-modified wafer-level silicon nanowire composite negative electrode material for a lithium ion battery and an integrated preparation method of the silver-modified wafer-level silicon nanowire composite negative electrode material, and the method comprises the following steps: putting a monocrystalline silicon wafer into acetone, absolute ethyl alcohol and deionized water in sequence for ultrasonic treatment to remove surface pollutants, and then carrying out vacuum drying for a certain time; the method comprises the following steps: placing a cleaned and dried monocrystalline silicon wafer in an HF-AgNO3-H2O2-deionized water solution system for metal-assisted etching treatment, placing the whole monocrystalline silicon wafer in a water bath at 40-70 DEG C for a certain time, then taking out the etched silicon wafer, cleaning a silver film attached to the surface by using a compressed air bottle, and cleaning the silicon wafer for multiple times by using absolute ethyl alcohol and deionized water in sequence; and carrying out vacuum drying on the etched and cleaned monocrystalline silicon wafer to integrally obtain the silver-modified silicon nanowire network composite negative electrode material. The composite negative electrode material is prepared by adopting a metal auxiliary etching method, the silver nanoparticles are integrally loaded on the silicon nanowire network by adopting a silver nanoparticle cascade disordered dispersion method, the preparation process is simple to operate, the requirement on experimental equipment is not high, the preparation cost is low, and the negative electrode material is high in structural stability and cycling stability and can be widely applied to the field of lithium ion batteries. The volume expansion is extremely small in the charge-discharge process, and the method is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery materials, and relates to a preparation method of a silver-modified silicon nanowire composite anode material for lithium-ion batteries. Background Art

[0002] Currently, the world is facing urgent challenges in terms of energy and the environment. Reducing the heavy dependence on traditional fossil fuels has become a top priority. Against this backdrop, the generation of electrical energy needs to be achieved in a cleaner and more sustainable way, including gradually replacing traditional coal and natural gas with renewable energy sources such as solar, wind, and hydro energy. As a key device for new energy power generation, secondary batteries provide the possibility for this energy conversion. At the same time, as electric vehicles gradually replace traditional fuel vehicles, the demand for compact secondary batteries with high driving capacity is increasing day by day. In these application scenarios, lithium batteries, as secondary batteries with the highest energy density, play an indispensable role. To achieve a breakthrough in the performance of lithium batteries without increasing weight, volume, and cost, it is necessary to upgrade the electrode materials of lithium batteries.

[0003] Carbonaceous electrodes have always been regarded as the standard anodes for lithium-ion batteries (LIBs), usually composed of graphite, with a relatively low theoretical capacity (i.e., 372 mA h g -1 ), a relatively low working voltage, and a long cycle life. In addition, other electrode materials such as tin, nickel, and silicon (Si) have been applied in LIBs. In particular, silicon has a theoretical capacity of more than 4200 mA h g -1 , so it is regarded as a potential option. Research shows that by improving electrode materials, the performance of lithium batteries can be significantly improved to meet the challenges of future energy demands. Therefore, it is of great significance to conduct further research and exploration on the electrode materials of lithium batteries.

[0004] The invention patent with publication number CN114566638A discloses a silicon nanowire, its preparation method and application, and a preparation method of a lithium-ion battery anode. By limiting the conditions of raw material concentration, hydrothermal reaction, and annealing treatment, amorphous silicon nanowires are obtained. The obtained material will not undergo a crystal form transformation when used as an electrode material, and the amorphous silicon nanowires have better tolerance to volume expansion. However, the silicon nanowire material prepared by this method has poor performance at high rates, and the preparation process requires high-temperature conditions, consuming too much energy. The invention patent with authorized publication number CN106207144B discloses a silicon nanowire, its preparation method, and the use for preparing a carbon-coated silicon nanowire anode material. The cathode sheet is sintered at a low temperature; then the obtained cathode sheet is fixed on an iron-chromium-aluminum wire as the cathode, and high-purity graphite is used as the anode, in CaCl 2In a molten salt system, electrolysis is carried out under a high-purity argon atmosphere to obtain silicon nanowires; an appropriate amount of acetylene black is ball-milled with the above silicon nanowires; the powder obtained by ball-milling is sintered under an inert atmosphere to obtain a carbon-coated silicon nanowire negative electrode material, which is used as a precursor to prepare a carbon-coated silicon nanowire negative electrode material and assembled into a battery. The battery exhibits very good battery cycling performance, stable electrochemical performance, and high energy density; however, this method has a complex process and requires high-temperature conditions for synthesis, which is not environmentally friendly enough. The invention patent with the authorized publication number ZL2021109594880 discloses a method for preparing a silicon-carbon composite negative electrode material for a lithium-ion battery using metallurgical waste silicon powder. This method includes subjecting the metallurgical-grade waste silicon powder to immersion purification treatment and metal-assisted etching treatment to obtain porous nano-silicon powder, and then preparing the silicon-carbon composite negative electrode material through a carbon source mixing and high-temperature calcination process. However, the technical feature of this technology is that the raw material is in powder form, and complex processes such as slurry coating are required to prepare the negative electrode sheet. The present invention provides an improved preparation method. Using a silicon wafer as the raw material, a silver-modified silicon nanowire composite negative electrode material is integrally prepared through a one-step etching process. This material has a porous block structure, can be directly bonded to the current collector to form a negative electrode sheet without going through intermediate processes such as slurry coating, and can be directly used for battery assembly. It has the characteristics of simple process, high efficiency, and environmental protection, and overcomes the technical defects of complex process and cumbersome procedures existing in the prior art. Summary of the Invention

[0005] To solve the problems described in the background art, the present invention provides a silver-modified wafer-level silicon nanowire composite negative electrode material for a lithium-ion battery and an integrated preparation method thereof.

[0006] The technical solution of the present invention includes the following steps:

[0007] (1) The single-crystal silicon wafer is sequentially placed in acetone, absolute ethanol, and deionized water for ultrasonic treatment to remove surface contaminants, and then vacuum-dried for a certain period of time;

[0008] (2) The cleaned and dried single-crystal silicon wafer is placed in an HF-AgNO 3 -H 2 O 2 -deionized water solution system for metal-assisted etching treatment, and the whole is placed in a water bath at 40-70 °C for a certain period of time. Subsequently, the etched silicon wafer is taken out, and the silver film attached to the surface is cleaned with a compressed air bottle, and then washed several times with absolute ethanol and deionized water in sequence;

[0009] (3) The etched and cleaned single-crystal silicon wafer is vacuum-dried, and a silver-modified silicon nanowire network composite negative electrode material can be integrally obtained;

[0010] (4) Coat the binder composed of sodium carboxymethylcellulose, acetylene black and styrene-butadiene rubber on the copper current collector, and then directly adhere the obtained silver-modified silicon nanowire network composite anode material onto the slurry. After drying and cutting, it can be directly used as the anode plate for battery assembly.

[0011] In the step (1) described above, the single-crystalline silicon wafer is a wafer-level P-type doped silicon wafer with a crystal orientation of (100), a specification of 4 inches or 6 inches, a thickness of 400 - 600 μm, and a resistivity of 1 - 10 Ω / cm.

[0012] In the step (1) described above, the ultrasonic time is 10 - 40 min.

[0013] In the step (1) described above, the temperature of vacuum drying is 60 - 80 °C and the time is 6 - 8 h.

[0014] In the step (2) described above, HF - AgNO 3 In the HF - deionized water solution system, the concentration of HF is 0.1 - 22.5 mol / L, the concentration of AgNO 3 is 0.005 - 2 mol / L, and the concentration of H 2 O 2 is 0.1 - 0.2 mol / L.

[0015] In the step (2) described above, the water bath time is 60 - 120 min.

[0016] In the step (2) described above, the pressure of the compressed air bottle is about 0.5 Mpa.

[0017] In the step (3) described above, the temperature of vacuum drying is 80 - 100 °C and the time is 8 - 12 h.

[0018] In the step (4) described above, the silver-modified silicon nanowire network composite anode material is directly adhered to the current collector. After drying and cutting, it can be directly used as the anode plate for battery assembly.

[0019] The present invention uses a metal-assisted etching method to prepare a silicon nanowire network, and integrally loads silver nanoparticles on the silicon nanowire network by a method of hierarchical disordered dispersion of silver nanoparticles.

[0020] Compared with the prior art, the present invention uses a metal-assisted etching method to prepare a silver-modified silicon nanowire network composite negative electrode material in an integrated manner. During the preparation process, silver nanoparticles are evenly distributed in the silicon nanowire material, which can effectively improve the rate performance and cycle stability of the negative electrode material, and is very suitable for the embedding and extraction of lithium ions during high-rate charge and discharge. By limiting the conditions such as the amount of raw materials, the concentration of different components of the etching solution, and the etching time, a silver-loaded silicon nanowire network is obtained. When used as an electrode material, the rich network and pore structure have better relief for volume expansion. In addition, the silver-modified silicon nanowire composite negative electrode material for lithium ion batteries of the present invention has a simple preparation process, low requirements for experimental equipment, and low preparation cost. The silver-modified silicon nanowire composite negative electrode material for lithium ion batteries has high structural stability and cycle stability, and extremely small volume expansion during charge and discharge, which is suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a cross-sectional SEM image of the silver-modified silicon nanowires prepared in Example 1.

[0022] Figure 2 This is a surface SEM image of the silver-modified silicon nanowires prepared in Example 1.

[0023] Figure 3 This is a digital photo of the silver-modified silicon nanowires prepared in Example 1 cut into 10 mm×10 mm.

[0024] Figure 4 This is a digital photo of the silver-modified silicon nanowires prepared in Example 1.

[0025] Figure 5 This is a high-magnification cross-sectional SEM image of the silver-modified silicon nanowires prepared in Example 1.

[0026] Figure 6 This is a cycle test chart of the button battery assembled with silver-modified silicon nanowires prepared in Example 1.

[0027] Figure 7 This is a digital photo of a small light bulb lit up by a soft-pack battery assembled with silver-modified silicon nanowires prepared in Example 1. DETAILED DESCRIPTION

[0028] The implementation of the present invention is described in detail below in conjunction with the accompanying drawings, but they do not constitute a limitation of the present invention, but are only examples. At the same time, through the description, the advantages of the present invention will be more clearly understood. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in the field should be considered as the protection scope of the present invention. Other parts not described in detail in the embodiments are all prior art.

[0029] Example 1

[0030] (1) The monocrystalline silicon wafer is successively placed in acetone, absolute ethanol, and deionized water and ultrasonically treated for 10 min to remove surface contaminants, and then vacuum-dried at 60 °C for 6 h;

[0031] (2) The cleaned and dried monocrystalline silicon wafer is placed in an HF-AgNO 3 -H 2 O 2 -deionized water solution system for metal-assisted etching treatment, and the whole is placed in a water bath at 40 °C for 60 min, where the HF concentration is 0.1 mol / L, AgNO 3 concentration is 0.005 mol / L, and H 2 O 2 concentration is 0.1 mol / L; Subsequently, the etched silicon wafer is taken out, and the silver film attached to the surface is cleaned with a compressed air bottle, and then successively washed several times with absolute ethanol and deionized water;

[0032] (3) The etched and cleaned monocrystalline silicon wafer is vacuum-dried at 80 °C for 8 h, and a silver-modified silicon nanowire network composite anode material can be integrally obtained;

[0033] (4) The binder composed of sodium carboxymethylcellulose, acetylene black, and styrene-butadiene rubber is coated on the copper current collector, and then the obtained silver-modified silicon nanowire network composite anode material is directly adhered to the slurry. After drying and cutting, it can be directly used as an anode plate for battery assembly.

[0034] Example 2

[0035] (1) The monocrystalline silicon wafer is successively placed in acetone, absolute ethanol, and deionized water and ultrasonically treated for 15 min to remove surface contaminants, and then vacuum-dried at 65 °C for 7 h;

[0036] (2) The cleaned and dried monocrystalline silicon wafer is placed in an HF-AgNO 3 -H 2 O 2 -deionized water solution system for metal-assisted etching treatment, and the whole is placed in a water bath at 45 °C for 70 min, where the HF concentration is 0.2 mol / L, AgNO 3 concentration is 0.01 mol / L, and H 2 O 2 concentration is 0.15 mol / L; Subsequently, the etched silicon wafer is taken out, and the silver film attached to the surface is cleaned with a compressed air bottle, and then successively washed several times with absolute ethanol and deionized water;

[0037] (3) The etched and cleaned monocrystalline silicon wafer is vacuum-dried at 90 °C for 9 h, and a silver-modified silicon nanowire network composite anode material can be integrally obtained;

[0038] (4) Coat the binder composed of sodium carboxymethyl cellulose, acetylene black, and styrene-butadiene rubber on the copper current collector. Subsequently, directly adhere the obtained silver-modified silicon nanowire network composite anode material onto the slurry. After drying and cutting, it can be directly used as the anode plate for battery assembly.

[0039] Example 3

[0040] (1) Put the single-crystalline silicon wafer into acetone, absolute ethanol, and deionized water in sequence and ultrasonically clean for 20 min to remove surface contaminants, then vacuum dry at 70 °C for 7 h;

[0041] (2) Place the cleaned and dried single-crystalline silicon wafer in the HF - AgNO 3 -H 2 O 2 -deionized water solution system for metal-assisted etching treatment, and place it in a water bath at 50 °C for 80 min as a whole. The concentration of HF is 0.3 mol / L, the concentration of AgNO 3 is 0.1 mol / L, and the concentration of H 2 O 2 is 0.20 mol / L; Subsequently, take out the etched silicon wafer, clean the silver film attached to the surface with a compressed air bottle, and wash it several times with absolute ethanol and deionized water in sequence;

[0042] (3) Vacuum dry the etched and cleaned single-crystalline silicon wafer at 100 °C for 10 h to integrally obtain the silver-modified silicon nanowire network composite anode material;

[0043] (4) Coat the binder composed of sodium carboxymethyl cellulose, acetylene black, and styrene-butadiene rubber on the copper current collector. Subsequently, directly adhere the obtained silver-modified silicon nanowire network composite anode material onto the slurry. After drying and cutting, it can be directly used as the anode plate for battery assembly.

[0044] Example 4

[0045] (1) Put the single-crystalline silicon wafer into acetone, absolute ethanol, and deionized water in sequence and ultrasonically clean for 25 min to remove surface contaminants, then vacuum dry at 80 °C for 8 h;

[0046] (2) Place the cleaned and dried single-crystalline silicon wafer in the HF - AgNO 3 -H 2 O 2 -deionized water solution system for metal-assisted etching treatment, and place it in a water bath at 55 °C for 90 min as a whole. The concentration of HF is 0.4 mol / L, the concentration of AgNO 3 is 0.2 mol / L, and the concentration of H 2 O 2The concentration is 0.20 mol / L; subsequently, the etched silicon wafer is taken out, and the silver film attached to the surface is cleaned with a compressed air bottle, and then washed several times with anhydrous ethanol and deionized water in sequence;

[0047] (3) The etched and cleaned single-crystalline silicon wafer is vacuum-dried at 80 °C for 11 h, and then a silver-modified silicon nanowire network composite anode material can be integrally obtained;

[0048] (4) The binder composed of sodium carboxymethylcellulose, acetylene black, and styrene-butadiene rubber is coated on the copper current collector, and then the obtained silver-modified silicon nanowire network composite anode material is directly adhered to the slurry. After drying and cutting, it can be directly used as an anode electrode sheet for battery assembly.

[0049] Example 5

[0050] (1) The single-crystalline silicon wafer is sequentially placed in acetone, anhydrous ethanol, and deionized water and ultrasonically treated for 30 min to remove surface contaminants, and then vacuum-dried at 80 °C for 8 h;

[0051] (2) The cleaned and dried single-crystalline silicon wafer is placed in an HF - AgNO 3 -H 2 O 2 - deionized water solution system for metal-assisted etching treatment, and the whole is placed in a water bath at 60 °C for 100 min, where the HF concentration is 0.5 mol / L, the AgNO 3 concentration is 0.3 mol / L, and the H 2 O 2 concentration is 0.15 mol / L; subsequently, the etched silicon wafer is taken out, and the silver film attached to the surface is cleaned with a compressed air bottle, and then washed several times with anhydrous ethanol and deionized water in sequence;

[0052] (3) The etched and cleaned single-crystalline silicon wafer is vacuum-dried at 80 °C for 12 h, and then a silver-modified silicon nanowire network composite anode material can be integrally obtained;

[0053] (4) The binder composed of sodium carboxymethylcellulose, acetylene black, and styrene-butadiene rubber is coated on the copper current collector, and then the obtained silver-modified silicon nanowire network composite anode material is directly adhered to the slurry. After drying and cutting, it can be directly used as an anode electrode sheet for battery assembly.

[0054] Example 6

[0055] (1) The single-crystalline silicon wafer is sequentially placed in acetone, anhydrous ethanol, and deionized water and ultrasonically treated for 40 min to remove surface contaminants, and then vacuum-dried at 80 °C for 6 h;

[0056] (2) The cleaned and dried single-crystalline silicon wafer is placed in an HF - AgNO 3 -H 2 O2 - The metal-assisted etching treatment was carried out in a deionized aqueous solution system, and the whole was placed in a water bath at 65 °C for 110 min, where the HF concentration was 1.0 mol / L, AgNO 3 concentration was 0.5 mol / L, H 2 O 2 concentration was 0.10 mol / L; Subsequently, the etched silicon wafer was taken out, and the silver film attached to the surface was cleaned with a compressed air bottle, and then washed several times with absolute ethanol and deionized water;

[0057] (3) The etched and cleaned single-crystalline silicon wafer was vacuum dried at 80 °C for 12 h, and the silver-modified silicon nanowire network composite anode material could be integrally obtained;

[0058] (4) The binder composed of sodium carboxymethyl cellulose, acetylene black and styrene-butadiene rubber was coated on the copper current collector, and then the obtained silver-modified silicon nanowire network composite anode material was directly adhered to the slurry. After drying and cutting, it could be directly used as the anode plate for battery assembly.

[0059] Example 7

[0060] (1) The single-crystalline silicon wafer was successively placed in acetone, absolute ethanol and deionized water and ultrasonically treated for 30 min to remove surface contaminants, and then vacuum dried at 60 °C for 6 h;

[0061] (2) The cleaned and dried single-crystalline silicon wafer was placed in an HF-AgNO 3 -H 2 O 2 - deionized aqueous solution system for metal-assisted etching treatment, and the whole was placed in a water bath at 70 °C for 120 min, where the HF concentration was 2.0 mol / L, AgNO 3 concentration was 1.0 mol / L, H 2 O 2 concentration was 0.10 mol / L; Subsequently, the etched silicon wafer was taken out, and the silver film attached to the surface was cleaned with a compressed air bottle, and then washed several times with absolute ethanol and deionized water;

[0062] (3) The etched and cleaned single-crystalline silicon wafer was vacuum dried at 80 °C for 8 h, and the silver-modified silicon nanowire network composite anode material could be integrally obtained;

[0063] (4) The binder composed of sodium carboxymethyl cellulose, acetylene black and styrene-butadiene rubber was coated on the copper current collector, and then the obtained silver-modified silicon nanowire network composite anode material was directly adhered to the slurry. After drying and cutting, it could be directly used as the anode plate for battery assembly.

[0064] Example 8

[0065] (1) Place the single-crystalline silicon wafer into acetone, absolute ethanol, and deionized water successively, and ultrasonically clean for 20 min to remove surface contaminants, then vacuum dry at 60 °C for 8 h;

[0066] (2) Place the cleaned and dried single-crystalline silicon wafer into the HF-AgNO 3 -H 2 O 2 -deionized water solution system for metal-assisted etching treatment, and place the whole in a water bath at 50 °C for 120 min, where the HF concentration is 4.0 mol / L, AgNO 3 concentration is 2.0 mol / L, and H 2 O 2 concentration is 0.20 mol / L; then take out the etched silicon wafer, clean the silver film attached to the surface with a compressed air bottle, and wash several times with absolute ethanol and deionized water in turn;

[0067] (3) Vacuum dry the etched and cleaned single-crystalline silicon wafer at 100 °C for 10 h, and then an integrated silver-modified silicon nanowire network composite anode material can be obtained;

[0068] (4) Coat the binder composed of sodium carboxymethyl cellulose, acetylene black, and styrene-butadiene rubber on the copper current collector, then directly adhere the obtained silver-modified silicon nanowire network composite anode material onto the slurry, and after drying and cutting, it can be directly used as an anode plate for battery assembly.

[0069] Example 9

[0070] (1) Place the single-crystalline silicon wafer into acetone, absolute ethanol, and deionized water successively, and ultrasonically clean for 30 min to remove surface contaminants, then vacuum dry at 70 °C for 7 h;

[0071] (2) Place the cleaned and dried single-crystalline silicon wafer into the HF-AgNO 3 -H 2 O 2 -deionized water solution system for metal-assisted etching treatment, and place the whole in a water bath at 60 °C for 120 min, where the HF concentration is 3.0 mol / L, AgNO 3 concentration is 1.50 mol / L, and H 2 O 2 concentration is 0.10 mol / L; then take out the etched silicon wafer, clean the silver film attached to the surface with a compressed air bottle, and wash several times with absolute ethanol and deionized water in turn;

[0072] (3) Vacuum dry the etched and cleaned single-crystalline silicon wafer at 80 °C for 10 h, and then an integrated silver-modified silicon nanowire network composite anode material can be obtained;

[0073] (4) Coat the adhesive composed of sodium carboxymethylcellulose, acetylene black, and styrene-butadiene rubber on the copper current collector. Subsequently, directly adhere the obtained silver-modified silicon nanowire network composite anode material onto the slurry. After drying and cutting, it can be directly used as the anode plate for battery assembly.

[0074] Example 10

[0075] (1) Put the single-crystalline silicon wafer into acetone, absolute ethanol, and deionized water in sequence and ultrasonically clean for 30 min to remove surface contaminants, and then vacuum dry at 80 °C for 8 h;

[0076] (2) Place the cleaned and dried single-crystalline silicon wafer in the HF-AgNO 3 -H 2 O 2 -deionized water solution system for metal-assisted etching treatment, and place it in a water bath at 50 °C for 120 min as a whole. The concentration of HF is 22.5 mol / L, the concentration of AgNO 3 is 2.0 mol / L, and the concentration of H 2 O 2 is 0.20 mol / L; then take out the etched silicon wafer, clean the silver film attached to the surface with a compressed air bottle, and wash it several times with absolute ethanol and deionized water in sequence;

[0077] (3) Vacuum dry the etched and cleaned single-crystalline silicon wafer at 80 °C for 8 h, and the silver-modified silicon nanowire network composite anode material can be integrally obtained;

[0078] (4) Coat the adhesive composed of sodium carboxymethylcellulose, acetylene black, and styrene-butadiene rubber on the copper current collector. Subsequently, directly adhere the obtained silver-modified silicon nanowire network composite anode material onto the slurry. After drying and cutting, it can be directly used as the anode plate for battery assembly.

[0079] The preferred embodiments of the present invention have been described in detail above in combination with the accompanying drawings and specific embodiments. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries and a method for its integrated preparation, characterized in that: The following steps are involved: (1) placing a single crystal silicon wafer in acetone, anhydrous ethanol and deionized water in turn for ultrasonic treatment to remove surface contaminants, and then vacuum drying for a certain period of time; (2) placing the cleaned and dried single crystal silicon wafer in a HF-AgNO3-H2O2-deionized water solution system for metal-assisted etching, and placing the whole in a water bath at 40-70° C. for a certain period of time, then taking out the etched silicon wafer, cleaning the silver film attached to the surface with a compressed air bottle, and washing it with anhydrous ethanol and deionized water several times in sequence; (3) vacuum drying the etched and cleaned single crystal silicon wafer to obtain a silver-modified silicon nanowire network composite negative electrode material; (4) A binder composed of sodium carboxymethyl cellulose, acetylene black and styrene-butadiene rubber is coated on the copper current collector, and then the obtained silver-modified silicon nanowire network composite negative electrode material is directly adhered to the slurry. After drying and cutting, it can be directly used as a negative electrode sheet for battery assembly.

2. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries according to claim 1 and the method for its integrated preparation are characterized in that: In the step (1), the single crystal silicon wafer is a wafer-level P-type doped silicon wafer with a crystal orientation of (100), a size of 4 inches or 6 inches, a thickness of 400-600 μm, and a resistivity of 1-10 Ω / cm.

3. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries according to claim 1 and the method for its integrated preparation are characterized in that: In the step (1), the ultrasonic time is 10-40 minutes.

4. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries according to claim 1 and the method for integrated preparation thereof, characterized in that: In the step (1), the vacuum drying temperature is 60-80°C and the time is 6-8h.

5. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries according to claim 1 and the method for its integrated preparation, characterized in that: In the step (2), the HF concentration in the HF-AgNO3-deionized water solution system is 0.1-22.5 mol / L, the AgNO3 concentration is 0.005-2 mol / L, and the H2O2 concentration is 0.1-0.2 mol / L.

6. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries and the method for its integrated preparation according to claim 1, characterized in that: In the step (2), the water bath time is 60-120 min.

7. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries and the method for integrated preparation thereof according to claim 1, characterized in that: In the step (2), the etched silicon wafer penetrates up and down, the internal silicon nanowires are crisscrossed, and the overall etching depth is 400-600 μm.

8. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries and the method for integrated preparation thereof according to claim 1, characterized in that: In the step (2), the pressure of the compressed air bottle is about 0.5 MPa.

9. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries and the method for integrated preparation thereof according to claim 1, characterized in that: In the step (3), the vacuum drying temperature is 80-100°C and the time is 8-12h.

10. The silver-modified wafer-level silicon nanowire composite negative electrode material for lithium-ion batteries and the method for its integrated preparation according to claim 1, characterized in that: In the step (4), the silver-modified silicon nanowire network composite negative electrode material is directly bonded to the current collector and can be directly used as a negative electrode plate for assembling a battery after being dried and cut.

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