Method for preparing nano silicon by adopting template-assisted chemical precipitation method

Abstract

The invention discloses a method for preparing nano silicon by adopting a template-assisted chemical precipitation method, and belongs to the technical field of nano material preparation. According to the method, CTATS (cetyltrimethylammonium p-toluenesulfonate) is taken as a template agent, TEA (triethanolamine) is taken as an alkali source, the pH value of a reaction system is regulated to 8.5-9.2, TEOS (tetraethyl orthosilicate) is taken as a silicon source, and controllable synthesis of the morphology, the size and the dispersity of nano silicon particles is realized by accurately regulating and controlling the molar ratio of CTATS / TEOS / TEA in the reaction system, the reaction temperature and template agent removal conditions; the method disclosed by the invention is simple in overall steps and can be used for large-batch production.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of nanomaterials, and particularly relates to a method for preparing nanosilicon by a template-assisted chemical precipitation method. Background Art

[0002] Due to its excellent physical and chemical properties, such as high theoretical specific capacity, significant quantum size effect and surface effect, nanosilicon materials exhibit great application potential in the fields of lithium-ion batteries, catalysis and semiconductor devices. Especially in the aspect of the anode material of lithium-ion batteries, nanosilicon is regarded as a key candidate material to break through the energy density bottleneck of existing graphite-based materials. However, its industrialization process is still limited by the key process problems existing in the existing preparation technologies.

[0003] At present, the chemical precipitation method is one of the mainstream methods for preparing nanosilicon, but it faces two major technical bottlenecks in practical applications: First, in the hydrolysis and polycondensation process of silicon precursors, due to the lack of an effective morphology control mechanism, silicic acid monomers are prone to disordered accumulation, resulting in uneven particle size distribution and serious particle agglomeration of the product. This not only reduces the specific surface area of the material, but also significantly deteriorates its electrochemical cycling stability due to the formation of secondary particles; Second, in the traditional process, the template agent is generally removed by high-temperature calcination (>800°C), which is likely to cause crystal structure distortion, a sharp increase in energy consumption, and may also cause oxidation of silicon particles or coarsening of grain boundaries, restricting the material properties. Although the alternative solution based on soft templates can reduce the treatment temperature, there is a problem that the surfactant residue is difficult to completely remove, affecting the interfacial properties and long-term stability of the material.

[0004] In recent years, researchers have tried to optimize the morphology control through composite template design or multi-step coating processes, such as adopting a technical route of multi-layer coating combined with secondary calcination. However, such methods often involve complex process flows (total time-consuming exceeding 48 hours) and harsh reaction conditions, significantly increasing the production cost and the difficulty of large-scale application. In addition, the synergistic regulation mechanism of hydrolysis kinetics and the role of template agents in the existing technology is still unclear, making the controllable preparation of nanosilicon lack general guiding principles. For example, in the patent with the application number 202111637754.4, "A ternary cathode material coated with nanoporous structure SiO2 and its preparation method and application", a ternary cathode material is synthesized by high-temperature solid-phase sintering, pulverized and classified, and then coated with a silica sol using ethanol as a solvent and tetraethyl orthosilicate as a silicon source. Through five process steps of simple high-temperature solid-phase sintering to form a matrix, preparing a silicon coating solution, dispersing and coating, hydrothermal-assisted drying, and secondary calcination, a ternary cathode material coated with nanoporous structure SiO2 is prepared. This process is obviously too cumbersome. Therefore, there is an urgent need to develop a green preparation method with simple process, low energy consumption and capable of precisely controlling the morphology of nanosilicon to promote its practical application in the fields of new energy and the like. Summary of the Invention

[0005] In view of the above technical problems, the present invention provides a method for preparing nanosilicon by a template-assisted chemical precipitation method.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the objects of the present invention is to provide a method for preparing nanosilicon by a template-assisted chemical precipitation method. In this method, tetraethyl orthosilicate is used as the silicon source, cetyltrimethyl p-toluenesulfonium ammonium is used as the template agent, and triethanolamine is used as the base source, and the pH of the reaction system is adjusted to 8.5 - 9.2.

[0008] Furthermore, the method for preparing nanosilicon by a template-assisted chemical precipitation method includes the following steps:

[0009] 1) Dissolve cetyltrimethyl p-toluenesulfonium ammonium (CTATS) in deionized water to obtain a template agent solution;

[0010] 2) Add triethanolamine (TEA) to the template agent solution, heat it in a water bath, and then continue to add tetraethyl orthosilicate (TEOS), and heat it in a water bath for the second time to obtain a white suspension. Filter it by suction and dry it to obtain a precursor powder;

[0011] 3) Add a hydrochloric acid-ethanol mixed solution to the precursor powder to remove the template agent, perform ultrasonic treatment, dry it, and grind it to obtain nanosilicon;

[0012] Among them, the molar ratio of cetyltrimethyl p-toluenesulfonium ammonium, triethanolamine, and tetraethyl orthosilicate is 0.006∶0.04∶0.05.

[0013] The present invention uses cetyltrimethyl p-toluenesulfonium ammonium as the template agent, triethanolamine as the base source, and tetraethyl orthosilicate as the silicon source. By introducing the directional confinement effect of the cetyltrimethyl p-toluenesulfonium ammonium template agent and combining with the dynamic hydrolysis-condensation regulation mechanism of triethanolamine, the problems of particle agglomeration and uncontrollable morphology caused by the disordered accumulation of silicic acid monomers in the traditional chemical precipitation method are solved, and monodisperse nanosilicon particles with a narrow particle size distribution (50 - 80 nm) are obtained. Through the precise ratio of the CTATS / TEOS / TEA molar ratio (0.06∶1∶1) and the step-by-step reaction control strategy, the traditional multi-step coating and secondary calcination processes are simplified (the total time is reduced by 80% to 8 hours), and an expandable preparation system is formed to meet the requirements of large-scale production.

[0014] Furthermore, the conditions for the water bath heating are: constant temperature stirring at 80°C for 1 h.

[0015] Furthermore, the conditions for the second water bath heating are: constant temperature stirring at 80°C for 2 h.

[0016] Further, the operating steps of the suction filtration include: performing gradient suction filtration using a filter membrane with a pore size of 0.1 μm under a vacuum degree of 4.5 - 5.0 kPa. Preferably, the suction filtration adopts a three-stage pressure control method, and the specific operating steps include:

[0017] In the first stage, maintain 2.5 kPa for 8 min to remove large particle aggregates;

[0018] In the second stage, increase to 4 kPa and hold for 12 min for collecting the main product;

[0019] In the third stage, perform pulsed suction filtration 5 times at 5 kPa to separate submicron-sized impurities.

[0020] Further, the specific operating steps of the drying include: fully removing the hydroxyl groups on the surface of the sample in a drying environment with a vacuum degree of -25 ± 1 Pa and a temperature of 100 ± 2 °C.

[0021] Further, the mass ratio of the precursor powder to the hydrochloric acid-ethanol mixed solution is 1:10.

[0022] Further, the volume ratio of hydrochloric acid to ethanol in the hydrochloric acid-ethanol mixed solution is 10:1.

[0023] Further, the conditions for removing the template agent are: constant temperature stirring at 50 ± 0.5 °C for 2 h.

[0024] The second object of the present invention is to provide a nano-silicon prepared by using the above preparation method.

[0025] The third object of the present invention is to provide an application of the nano-silicon as a cathode material for lithium batteries

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] The present invention uses cetyltrimethyl p-toluenesulfonate as the template agent, triethanolamine as the base source, and tetraethyl orthosilicate as the silicon source, and explores the synthesis mechanism of nano-silicon by regulating the ratio of the base source to the silicon source. The overall preparation method is relatively simple and can be mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 It is a scanning TEM electron micrograph (200 nm) of the nano-silicon particles prepared in Example 1;

[0030] Figure 2Scanning TEM electron micrograph of the nanosilicon particles prepared in Example 1 (50 nm);

[0031] Figure 3 Scanning TEM electron micrograph of the nanosilicon particles prepared in Comparative Example 1;

[0032] Figure 4 Scanning TEM electron micrograph of the nanosilicon particles prepared in Comparative Example 2;

[0033] Figure 5 Scanning TEM electron micrograph of the nanosilicon particles prepared in Comparative Example 3;

[0034] Figure 6 Scanning TEM electron micrograph of the nanosilicon particles prepared in Comparative Example 4;

[0035] Figure 7 X-ray diffraction test data of the nanosilicon particles prepared in Example 1;

[0036] Figure 8 Specific surface area test data of the nanosilicon particles prepared in Example 1;

[0037] Figure 9 Three-electrode test data of the nanosilicon particles prepared in Example 1. Detailed implementation mode

[0038] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0039] It should be understood that the terms used in the present invention are only for describing specific implementation modes and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0040] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0041] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and examples are merely exemplary.

[0042] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0043] The present invention realizes the controllable preparation of nanosilicon particles by introducing a template agent-alkali source synergistic regulation mechanism and adopting a template-assisted chemical precipitation method.

[0044] Directed confinement growth: Using tetraethyl orthosilicate (TEOS) as the silicon source, through the molecular self-assembly characteristics of the cetyltrimethyl p-toluenesulfonium ammonium (CTATS) template agent, an ordered nano-scale pore structure is formed in the reaction system. This template agent precisely guides the condensation of silicic acid aggregates in a specific direction through electrostatic interaction and steric hindrance effect, inhibiting disordered accumulation.

[0045] Dynamic hydrolysis control: Triethanolamine (TEA) is introduced as a bifunctional additive. Its basic group delays the hydrolysis rate of tetraethyl silicate by regulating the pH value of the reaction system (optimal range 8.5 - 9.2), and at the same time its long-chain molecules adsorb on the surface of nanosilicon to form an interfacial passivation layer, thus synchronously solving the problems of particle agglomeration and size uniformity.

[0046] Low-temperature and high-efficiency synthesis: Compared with the traditional high-temperature solid-phase method (>1000 °C) and wet chemical method (purity < 90%), this method prepares monodisperse nanosilicon particles under mild conditions of 80 °C through the synergistic effect of "template confinement + dynamic pH regulation".

[0047] Through the above principles, the technical effect achieved by the present invention is that nanosilicon particles with uniform particle size distribution and controllable size can be prepared.

[0048] The embodiment of the present invention provides a method for preparing nanosilicon by using a template-assisted chemical precipitation method. Using cetyltrimethyl p-toluenesulfonium ammonium (CTATS) as the template agent, triethanolamine (TEA) as the alkali source, and tetraethyl orthosilicate (TEOS) as the silicon source, the controllable synthesis of the morphology, size, and dispersibility of nanosilicon particles is achieved by precisely regulating the molar ratio of CTATS / TEOS / TEA, reaction temperature, and template agent removal conditions in the reaction system. The specific steps are as follows:

[0049] 1) Dissolve cetyltrimethyl p-toluenesulfonium ammonium in deionized water to obtain a template agent solution with a concentration of 0.06 mol / L;

[0050] 2) Add triethanolamine to the template agent solution, stir for 1 h in a constant temperature water bath at 80 °C, then continue to add tetraethyl orthosilicate, and continue to stir for 2 h in a constant temperature water bath at 80 °C to obtain a white suspension. Filter by suction, dry to obtain a precursor powder. Stirring continuously for 3 h in a constant temperature water bath at 80 °C can achieve gentle hydrolysis-condensation of tetraethyl silicate, avoiding rapid nucleation and particle coarsening caused by high temperature (such as >100 °C);

[0051] 3) Add a hydrochloric acid-ethanol mixed solution to the precursor powder to remove the template agent, perform ultrasonic treatment, dry and grind to obtain nano-silicon.

[0052] Among them, the molar ratio of cetyltrimethyl p-toluenesulfonium ammonium, tetraethyl orthosilicate and triethanolamine is 0.006∶0.04∶0.05.

[0053] In some preferred embodiments, the suction filtration adopts a three-stage pressure control method, and the specific operation steps include:

[0054] In the first stage, maintain 2.5 kPa for 8 min to remove large particle aggregates;

[0055] In the second stage, increase to 4 kPa and hold for 12 min for main product collection;

[0056] In the third stage, use 5 kPa pulsed suction filtration 5 times to separate submicron-sized impurities.

[0057] Separating particles of different particle sizes in three stages (2.5 kPa → 4 kPa → 5 kPa pulsed) can improve the dispersibility of the product.

[0058] In some preferred embodiments, the specific operation steps of the drying include: fully removing the surface hydroxyl groups of the sample in a drying environment with a vacuum degree of -25 ± 1 Pa and a temperature of 100 ± 2 °C.

[0059] In some preferred embodiments, the mass ratio of the precursor powder to the hydrochloric acid-ethanol mixed solution is 1∶10. The volume ratio of hydrochloric acid (37%) to ethanol (99%) in the hydrochloric acid-ethanol mixed solution is 10∶1. The conditions for removing the template agent are: stir at a constant temperature of 50 ± 0.5 °C for 2 h. Under these conditions, the template agent can be completely removed (residual amount < 0.1 wt%), which can avoid the influence of impurities on the electrochemical performance of the material and the damage of the silicon lattice structure by high temperature.

[0060] In some preferred embodiments, the conditions for the ultrasonic treatment are: perform ultrasonic treatment with a power of 400 W and a frequency of 40 kHz for 50 min.

[0061] Using the above preparation method, nano-silicon can be prepared.

[0062] The present invention adopts a template-assisted chemical precipitation method to synthesize materials with special structures and regular orientations under isothermal and isobaric conditions. By precisely controlling the dosage of triethanolamine (alkali source), its chemical effects are as follows: ① Controlling the hydrolysis reaction rate and inducing the formation of long-chain polymers of silicic acid in the organic phase; ② Restricting the nucleation and growth kinetics of silica sol particles, and finally stably controlling the product particle size within the range of 50-80 nm. Through process optimization, 6 mL is determined as the optimal feeding threshold of triethanolamine.

[0063] In the present invention, unless otherwise specified, "room temperature" refers to 20-30 °C.

[0064] All raw materials used in the present invention are obtained by purchasing on the market.

[0065] The technical solution of the present invention is further described below through examples.

[0066] Example 1

[0067] A method for preparing nanosilicon by a template-assisted chemical precipitation method (the molar ratio of cetyltrimethyl p-toluenesulfonate, tetraethyl orthosilicate and triethanolamine is 0.006:0.04:0.05), comprising the following steps:

[0068] (1) Dissolve 2.74 ± 0.05 g of cetyltrimethyl p-toluenesulfonate (0.006 mol) in 150 mL of deionized water, control the water bath temperature at 35 ± 1 °C to promote the full dissolution of the reagent to form a stable micelle system, and obtain a template agent solution;

[0069] (2) Add 6 mL of triethanolamine (0.05 mol) as a catalytic alkali source to the obtained template agent solution, continuously stir and react at 80 °C for 1 h, and reduce the hydrolysis rate of the silicon source by precisely controlling the temperature and time parameters;

[0070] (3) Continue to add 7.02 ± 0.1 mL of tetraethyl orthosilicate (0.04 mol), and carry out a coating reaction at 80 °C for 2 h. This temperature combination reduces the activation energy of the silane hydrolysis and polycondensation reaction;

[0071] (4) Filter the sample obtained in step (3). The filtration adopts a three-stage pressure control method. The specific operation steps are as follows: In the first stage, maintain 2.5 kPa for 8 min to remove large particle aggregates; in the second stage, increase to 4 kPa and keep it for 12 min for the collection of the main product; in the third stage, use 5 kPa pulse filtration 5 times to separate submicron impurities and improve the retention rate of primary particles;

[0072] (5) Set a vacuum degree of -25 ± 1 Pa and a drying environment of 100 ± 2 °C to fully remove the hydroxyl groups on the surface of the sample obtained in step (4) to obtain a precursor powder;

[0073] (6) Mix the precursor powder with a hydrochloric acid - ethanol mixed solution (the volume ratio of hydrochloric acid to ethanol is 10:1) at a mass ratio of 1:10, treat it at 50 ± 0.5 °C for 2 h to remove the template agent, and then perform ultrasonic treatment at a power of 400 W and a frequency of 40 kHz for 50 min to narrow the average particle size from the initial particle size distribution range. After drying after ultrasonic treatment, nano - silicon particles are obtained.

[0074] Comparative Example 1

[0075] A method for preparing nano - silicon by template - assisted chemical precipitation method (the molar ratio of cetyltrimethyl p - toluenesulfonium ammonium, tetraethyl orthosilicate and triethanolamine is 0.006:0.04:0.02), including the following steps:

[0076] Same as Example 1, the difference is that the addition amount of triethanolamine in step (2) is 3 mL (0.02 mol).

[0077] Comparative Example 2

[0078] A method for preparing nano - silicon by template - assisted chemical precipitation method (the molar ratio of cetyltrimethyl p - toluenesulfonium ammonium, tetraethyl orthosilicate and triethanolamine is 0.06:0.04:0), including the following steps:

[0079] Same as Example 1, the difference is that triethanolamine is not added, that is, step (2) is not carried out.

[0080] Figures 1-2 It is the scanning TEM electron micrograph and enlarged view of the nano - silicon particles prepared in Example 1. From Figures 1-2 It can be seen that when the molar ratio of cetyltrimethyl p - toluenesulfonium ammonium, tetraethyl orthosilicate and triethanolamine is 0.06:0.04:0.05, triethanolamine, as a strong base source, significantly slows down the hydrolysis rate of tetraethyl silicate, promotes the step - by - step polycondensation of silicic acid monomers, and forms monodisperse and uniform - sized nano - particles (50 - 80 nm).

[0081] Figure 3 It is the scanning TEM electron micrograph of the nano - silicon particles prepared in Comparative Example 1. From Figure 3 It can be seen that when the molar ratio of cetyltrimethyl p - toluenesulfonium ammonium, tetraethyl orthosilicate and triethanolamine is 0.06:0.04:0.02, the hydrolysis rate increases, the particle size increases to 80 - 120 nm, and the dispersibility decreases (TEM shows slight agglomeration).

[0082] Figure 4 It is the scanning TEM electron micrograph of the nano - silicon particles prepared in Comparative Example 2. From Figure 4It can be seen that when triethanolamine is completely absent, the hydrolysis of tetraethyl orthosilicate gets out of control and regular nanoparticles cannot be formed (TEM shows an amorphous structure).

[0083] Comparative Example 3

[0084] Same as Example 1, except that the reaction temperature in steps (2) and (3) was adjusted to 60 °C.

[0085] Figure 5 Figure 10 is a scanning TEM electron micrograph of the nano-silicon particles prepared in Comparative Example 3. From Figure 5 it can be seen that the particle size distribution becomes wider in the range of 50 - 150 nm, forming an irregular polyhedral structure, accompanied by the bridging aggregation of secondary particles. The image clarity decreases due to the low temperature resulting in a decrease in crystallinity, and the TEM image will show a relatively blurred state. It is proved that 80 °C is the lowest critical temperature to maintain the directional guiding effect of the template agent.

[0086] Comparative Example 4

[0087] Same as Example 1, except that the template agent was replaced with deionized water, that is, step (6) was: mixing the precursor powder and deionized water in a mass ratio of 1:10, treating at 50 ± 0.5 °C for 2 h to remove the template agent, and then performing ultrasonic treatment at a power of 400 W and a frequency of 40 kHz for 50 min to narrow the initial particle size distribution range, and drying after ultrasonic treatment.

[0088] Figure 6 Figure 11 is a scanning TEM electron micrograph of the nano-silicon particles prepared in Comparative Example 4. From Figure 6 it can be seen that the product shows an irregular block structure and severe aggregation, and the particle size distribution is uneven, confirming that the absence of the template agent leads to the disordered accumulation of silicic acid monomers and the inability to achieve morphology control.

[0089] Figure 7 Figure 12 shows the X-ray diffraction test data of the nano-silicon particles prepared in Example 1. The nano-silicon particles show sharp characteristic diffraction peaks of silicon crystals in the XRD pattern, indicating that the product has high crystallinity. These clear and sharp peak shapes indicate that the template-assisted chemical precipitation method has successfully achieved the ordered polycondensation of silicon, and the synergistic effect of the template agent (CTATS) and triethanolamine (TEA) effectively inhibits the formation of amorphous or non-crystalline structures. The full width at half maximum of the XRD diffraction peak, calculated by the Scherrer formula, shows that the grain size is 50 - 80 nm, which is consistent with the TEM results of Example 1 ( Figures 1-2 ), confirming the precise confinement effect of the template agent on the silicon particle size. Figure 7 The XRD data clearly supports that the method described in Example 1 has successfully synthesized nano-silicon particles with high purity, complete crystal form and uniform grain size, providing a structural basis for their use as the cathode material of lithium batteries.

[0090] Figure 8 The specific surface area test data of the nano-silicon particles prepared in Example 1 shows that Figure 8 the nano-silicon particles have a developed mesoporous structure. The adsorption-desorption curve shows an obvious hysteresis loop in the relative pressure range of 0.4 - 0.8. The BJH pore size distribution curve indicates that the pore size of the material is concentrated in the range of 5 - 8 nm. There is no sudden increase in the adsorption amount in the low-pressure region (P / P0 < 0.1) of the desorption curve, which proves that the vacuum drying process (-25 Pa, 100 °C) effectively removes the surface hydroxyl groups of the precursor, avoids the collapse of the microporous structure during the subsequent removal of the template agent, and is beneficial to maintaining the structural stability.

[0091] Figure 9 The three-electrode test data of the nano-silicon particles prepared in Example 1 shows that Figure 9 the first efficiency (initial Coulomb efficiency) of the nano-silicon material is relatively high, which proves that the nano-silicon synthesized by the CTATS template-assisted method has a dense structure and few side reactions on the surface. The cycling performance graph shows a stable capacity retention rate, indicating that the monodisperse nanostructure effectively alleviates the problem of particle fragmentation caused by the volume expansion of silicon (>300%).

[0092] It can be obtained from the semicircle radius of the electrochemical impedance spectrum (EIS) that the nano-silicon in Example 1 has a low interfacial impedance (such as the semicircle diameter < 50 Ω), reflecting good contact between the material and the electrolyte. If there is an obvious voltage plateau in the charge-discharge curve, it indicates a high reversibility during the lithiation process, further verifying that the nano-silicon particles have good size and dispersibility (see the TEM results in Figures 1-2 ).

[0093] Figure 9 The above data fully prove that the nano-silicon in Example 1 has the core indicators of a high-performance lithium battery cathode material: high capacity, long cycle life, and high rate performance, meeting the technical effect statement regarding "the application of lithium battery cathode materials".

[0094] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing nanosilicon by template-assisted chemical precipitation method, characterized in that, Using tetraethyl orthosilicate as the silicon source, cetyltrimethyl p-toluenesulfonium ammonium as the template agent, and triethanolamine as the base source, the pH of the reaction system was adjusted to 8.5 - 9.

2.

2. The method for preparing nano-silicon by using a template-assisted chemical precipitation method according to claim 1, wherein, It includes the following steps: 1) Dissolve cetyltrimethyl p-toluenesulfonium ammonium in deionized water to obtain a template agent solution; 2) Add triethanolamine to the template agent solution, heat it in a water bath, then continue to add tetraethyl orthosilicate, and heat it in a water bath for the second time to obtain a white suspension. Filter it by suction, dry it to obtain a precursor powder; 3) Add a hydrochloric acid-ethanol mixed solution to the precursor powder to remove the template agent, perform ultrasonic treatment, dry it in an oven, and grind it to obtain nano-silicon; Among them, the molar ratio of cetyltrimethyl p-toluenesulfonium ammonium, triethanolamine, and tetraethyl orthosilicate is 0.006∶0.04∶0.

05.

3. The method for preparing nano-silicon by template-assisted chemical precipitation according to claim 2, wherein, The conditions for the water bath heating are: constant temperature stirring at 80°C for 1 h; and / or, The conditions for the second water bath heating are: constant temperature stirring at 80°C for 2 h.

4. The method for preparing nano-silicon by template-assisted chemical precipitation according to claim 2, characterized in that, The specific operation steps of the suction filtration include: performing gradient suction filtration with a filter membrane with a pore size of 0.1 μm under a vacuum degree of 4.5 - 5.0 kPa.

5. The method for preparing nano-silicon by using a template-assisted chemical precipitation method according to claim 2, characterized in that, The specific operation steps of the drying include: fully removing the surface hydroxyl groups of the sample in a drying environment with a vacuum degree of -25 ± 1 Pa and a temperature of 100 ± 2°C.

6. The method for preparing nano-silicon by template-assisted chemical precipitation method according to claim 2, characterized in that, The mass ratio of the precursor powder to the hydrochloric acid-ethanol mixed solution is 1∶10.

7. The method for preparing nano-silicon by template-assisted chemical precipitation according to claim 6, characterized in that, The volume ratio of hydrochloric acid to ethanol in the hydrochloric acid-ethanol mixed solution is 10∶1.

8. The method for preparing nano-silicon by using a template-assisted chemical precipitation method according to claim 1, characterized in that, The conditions for removing the template agent are: constant temperature stirring at 50 ± 0.5°C for 2 h.

9. A nano-silicon prepared by using the method according to any one of claims 1 - 8.

10. An application of the nano-silicon according to claim 9 as a cathode material for a lithium battery.

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