A method for preparing porous hollow silicon spheres using hollow glass microspheres and its application

Abstract

The present application relates to the technical field of chemical material preparation, and in particular to a method for preparing porous hollow silicon spheres using hollow glass microspheres and its application; the method comprises: heating the hollow glass microspheres and keeping them warm to cause a spinodal decomposition reaction to obtain treated hollow glass microspheres; acid etching the treated hollow glass microspheres, filtering them, and then rapidly heating them to obtain porous amorphous SiO2 particles; adding magnesium powder to the porous amorphous SiO2 particles, ball milling them, and then performing a magnesium thermal reduction reaction in an oxygen-free environment to obtain a mixture containing nano-silicon and magnesium oxide; adding the mixture to hydrochloric acid, rinsing and filtering it, and then drying it to obtain porous hollow silicon spheres; the method can overcome the problem in the prior art that Si negative electrode is heated in the presence of Li + The volume change during the deintercalation / embedding process and maintaining structural stability can extend the cycle life of lithium-ion batteries. At the same time, the preparation process of this method is simple, low-cost and conducive to commercialization.

Description

Technical Field

[0001] The present application relates to the technical field of chemical material preparation, and in particular to a method for preparing porous hollow silicon spheres using hollow glass microspheres and its application. Background Art

[0002] Since the capacity of the cathode material of commercial lithium-ion batteries is limited, and the capacity of the anode material graphite is close to the theoretical value of 372mAh g -1 ), while Si material has a capacity of up to 3578 mAh g -1 The specific capacity and 0.4V (vs Li / Li + ) has a lower discharge potential, and Si materials have many advantages such as abundant resources, environmental friendliness and no need for high purity, but the silicon negative electrode is + The volume expansion during the deintercalation / insertion process is huge (~300%), which limits the application of silicon in the negative electrode. Although the porous Si structure, nanotubes, hollow spheres and other methods have been used to alleviate the Li + The volume change of the Si negative electrode during the deintercalation / intercalation process is used to maintain structural stability and extend the cycle life of the lithium-ion battery. However, most of the processes are complex, expensive and not conducive to commercialization.

[0003] Hollow glass microspheres are a new material developed in recent years that has a wide range of uses and excellent performance. The main component of this product is borosilicate. These hollow spheres typically have a particle size of 10 to 250 μm and a wall thickness of 1 to 2 μm. They also offer advantages such as light weight, low thermal conductivity, high strength, good chemical stability, and high dispersion. Their chemical components include SiO2, K2O, Al2O3, and B2O3. Therefore, converting low-value SiO2 materials into negative electrode Si materials through magnesium thermal reduction is a low-cost, scalable, and feasible path. Furthermore, magnesium thermal reduction, a pseudomorphic transformation, maintains the precursor structure unchanged before and after reduction, allowing the replication of various intricate SiO2 structural features onto Si products.

[0004] The current methods for magnesium thermal reduction process include: (1) a method for preparing hollow nano-silicon spheres by metal thermal reduction, wherein active metal powder is mixed with silica nano-spheres, ball-milled, and then transferred into a crucible, and heated to the thermal reduction reaction temperature under argon protection or vacuum conditions, kept warm for reaction, and then naturally cooled to obtain an active metal oxide / silicon / silicon dioxide composite; the prepared composite is mixed with acid solution, stirred for reaction, and then washed with water to obtain a hollow silica sphere nano-silicon dioxide composite material; the silicon precursor used in this method is silica nano-spheres, which have a delicate structure and are nano-materials. They are expensive and not conducive to commercialization.

[0005] (2) A method for preparing micron-sized porous hollow silicon spheres, comprising: placing magnesium powder in an anhydrous ethanol solution of 3-mercaptopropyltriethoxysilane for a series of chemical modifications, and then magnetically stirring the magnesium powder to coat silica microsphere powder; and then treating the resulting powder, etching it with acid, and drying it to produce porous hollow silicon spheres. The method is then applied to silicon-based lithium-ion batteries. This method aims to prepare magnesium powder-coated silica microsphere powder. The chemical process for synthesizing hollow silicon spheres is complex, making it unsuitable for commercialization.

[0006] (3) A carbon-coated hollow silica composite material and its preparation method, wherein polyacrylic acid is used as a raw material to prepare polyacrylic acid microspheres, and then anhydrous ethanol, tetraethyl orthosilicate, and ammonia are added to deposit the in-situ generated silica on the surface of the polyacrylic acid microspheres, forming a silica layer coating the outside of the polyacrylic acid. The polyacrylic acid is repeatedly rinsed with deionized water until hollow silica microspheres are formed. The microspheres are then carbon-coated and applied to silicon-based lithium-ion batteries. This method still has a complex chemical process for synthesizing hollow silica microspheres, which is not conducive to commercialization.

[0007] (4) A method for preparing hollow porous micron-sized silicon spheres, silicon-based negative electrode materials, and lithium-ion batteries, comprising reducing hollow glass microspheres with an active metal and then removing the metal oxides with an acid to obtain hollow porous micron-sized silicon spheres. Silicon-based negative electrodes and lithium-ion batteries are then fabricated based on the hollow porous micron-sized silicon spheres. This method does not describe hollow glass microspheres.

[0008] Therefore, how to provide a method for preparing porous hollow silicon spheres using glass hollow microspheres to achieve simple process, low cost and commercialization while maintaining structural stability is a technical problem that needs to be solved urgently. Summary of the Invention

[0009] The present application provides a method for preparing porous hollow silicon spheres using hollow glass microspheres and its application, in order to solve the technical problems in the prior art of maintaining structural stability while being difficult to achieve simple process, low cost and commercialization.

[0010] In a first aspect, the present application provides a method for preparing porous hollow silicon spheres using hollow glass microspheres, the method comprising:

[0011] Heating the hollow glass microspheres and keeping them warm to cause a spinodal decomposition reaction, thereby obtaining treated hollow glass microspheres in which SiO2 and other oxide microregions are alternately distributed;

[0012] Acid etching the treated glass hollow microspheres, filtering them, and then rapidly heating them to obtain porous amorphous SiO2 particles;

[0013] Adding magnesium powder to the porous amorphous SiO2 particles, ball milling, and then performing a magnesium thermal reduction reaction in an oxygen-free environment to obtain a mixture containing nano-silicon and magnesium oxide;

[0014] The mixture is added to hydrochloric acid, rinsed and filtered, and then dried to obtain porous hollow silicon spheres.

[0015] Optionally, the end temperature T of the heating satisfies:

[0016] 0.85Ts≤T≤Ts,

[0017] Wherein, Ts is the stable temperature of the spinodal decomposition reaction.

[0018] Optionally, the particle size of the hollow glass microspheres is 10 μm to 30 μm, and the wall thickness of the hollow glass microspheres is 1 μm to 2 μm.

[0019] Optionally, the insulation time is 1 hour to 24 hours.

[0020] Optionally, the endpoint temperature of the rapid heating is ≥1500°C.

[0021] Optionally, the mass ratio of the porous amorphous SiO2 particles to the magnesium powder is ≥1.

[0022] Optionally, the ball milling time is ≥ 2 h; and / or,

[0023] The particle size of the magnesium powder is ≤30 μm.

[0024] Optionally, the magnesium thermal reduction reaction includes a heating stage and a heat preservation stage, the terminal temperature of the heating stage is 500° C. to 800° C., and the time of the heat preservation stage is 2 h to 6 h.

[0025] Optionally, the acid solution used for the acid etching is hydrochloric acid, and the ratio of the mass of the treated hollow glass microspheres to the amount of the acid solution used for the acid etching is ≥1 g / mol.

[0026] In a second aspect, the present application provides an application of a method for preparing porous hollow silicon spheres using hollow glass microspheres, wherein the porous hollow silicon spheres obtained by the method described in the first aspect are used to prepare battery negative electrode materials.

[0027] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0028] The embodiment of the present application provides a method for preparing porous hollow silicon balls using hollow glass microspheres. Compared with traditional porous hollow silicon balls, the method does not require the separate design of an expensive and sophisticated Si precursor hollow ball structure. It only requires the glass hollow microspheres to be heated until a spinodal decomposition reaction occurs, thereby achieving micro-regional phase distribution between SiO2 and other oxides, and then removing impurities in the hollow glass microspheres through acid etching and rapid heating to obtain pure porous amorphous SiO2 particles, and then through a magnesium thermal reduction reaction, the porous amorphous SiO2 particles are converted into porous hollow silicon balls. The above process only requires a simple preliminary spinodal decomposition reaction and a magnesium thermal reduction reaction to obtain porous hollow silicon balls, thereby overcoming the problem of Si negative electrode in Li + The volume change during the deintercalation / embedding process and maintaining structural stability can extend the cycle life of lithium-ion batteries. At the same time, the preparation process of this method is simple, low-cost and conducive to commercialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A schematic flow chart of a method for preparing porous hollow silicon spheres using hollow glass microspheres provided in an embodiment of the present application;

[0032] Figure 2 XRD pattern of porous amorphous SiO2 particles provided in the examples of the present application;

[0033] Figure 3 The XRD pattern of the porous hollow silicon spheres after acid etching provided in the examples of the present application;

[0034] Figure 4 This is a diagram of N2 desorption-adsorption of the acid-etched porous hollow silicon spheres provided in the examples of the present application;

[0035] Figure 5 This is an electrochemical curve of the Si@C negative electrode material provided in the embodiment of the present application after 400 cycles at a current density of 0.2 A / g. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0038] like Figure 1 As shown, the embodiment of the present application provides a method for preparing porous hollow silicon spheres using hollow glass microspheres, the method comprising:

[0039] S1 is heated and kept warm for the hollow glass microspheres to undergo spinodal decomposition reaction to obtain SiO2 and other oxide microregions interspersed with the treated hollow glass microspheres;

[0040] S2. The treated glass hollow microspheres were acid-etched and filtered, and then rapidly heated to obtain porous amorphous SiO2 particles;

[0041] S3. Magnesium powder was added to the porous amorphous SiO2 particles and ball-milled, and then subjected to magnesium thermal reduction reaction in an oxygen-free environment to obtain a mixture containing porous silicon and magnesium oxide;

[0042] S4. Add the mixture to hydrochloric acid, rinse and filter, and then dry to obtain porous hollow silicon spheres.

[0043] In some optional embodiments, the end temperature T of the heating satisfies:

[0044] 0.85Ts≤T≤Ts,

[0045] Wherein, Ts is the stable temperature of the spinodal decomposition reaction.

[0046] In the embodiment of the present application, the relationship between the specific end point temperature T of the heating and the stable temperature of the spinodal decomposition reaction is controlled. Since the optimal and fastest temperature of the spinodal decomposition reaction is 10% below Ts, the hollow glass microspheres can be prompted to undergo spinodal decomposition reaction under appropriate temperature conditions within this temperature range.

[0047] In some optional embodiments, the particle size of the hollow glass microspheres is 10 μm to 30 μm, and the wall thickness of the hollow glass microspheres is 1 μm to 2 μm.

[0048] In the embodiments of the present application, the specific particle size and specific wall thickness of the hollow glass microspheres are controlled so that the hollow glass microspheres react fully in the spinodal decomposition reaction, thereby achieving micro-regional interphase distribution of SiO2 and other oxides. At the same time, acid etching and rapid heating are facilitated, and finally, porous hollow silicon spheres with appropriate particle size and wall thickness can be obtained.

[0049] In some optional embodiments, the insulation time is 1 hour to 24 hours.

[0050] In the embodiment of the present application, the specific holding time is controlled so that the spinodal decomposition reaction can proceed fully, thereby obtaining treated glass hollow microspheres with SiO2 and other oxide microregions distributed alternately, which facilitates the complete removal of K2O, Al2O3 and part of B2O3 impurities in the subsequent acid etching process.

[0051] In some optional embodiments, the endpoint temperature of the rapid heating is ≥1500°C.

[0052] In the embodiment of the present application, by controlling the specific end temperature of the rapid heating, the residual boron oxide can be directly sublimated by high temperature, thereby obtaining pure porous amorphous SiO2 particles.

[0053] In some optional embodiments, the mass ratio of the porous amorphous SiO2 particles to the magnesium powder is ≥1.

[0054] In the embodiment of the present application, the specific mass ratio of the porous amorphous SiO2 particles and the magnesium powder is controlled so that the magnesium powder content is sufficient, thereby allowing the magnesium thermal reduction reaction to proceed smoothly and obtaining a mixture of nano-silicon and magnesium oxide.

[0055] In some optional embodiments, the ball milling time is ≥ 2 h; and / or,

[0056] The particle size of the magnesium powder is ≤30 μm.

[0057] In the embodiment of the present application, the specific time of ball milling is controlled to ensure sufficient mixing between the porous amorphous SiO2 particles and the magnesium powder, while also inducing a magnesium thermal reduction reaction.

[0058] Controlling the specific particle size of the magnesium powder can promote sufficient mixing between the magnesium powder and the porous amorphous SiO2 particles, while also allowing the subsequent magnesium thermal reduction reaction to proceed fully, thereby obtaining a sufficient mixture of nano-silicon and magnesium oxide.

[0059] In some optional embodiments, the magnesium thermal reduction reaction includes a heating stage and a heat preservation stage, the terminal temperature of the heating stage is 500° C. to 800° C., and the time of the heat preservation stage is 2 h to 6 h.

[0060] In the embodiment of the present application, the specific end temperature of the heating stage and the specific time of the holding stage of the magnesium thermal reduction reaction are controlled so that the magnesium thermal reduction reaction can be fully carried out, thereby obtaining a sufficient mixture of nano-silicon and magnesium oxide.

[0061] In some optional embodiments, the acid solution used for the acid etching is hydrochloric acid, and the ratio of the mass of the treated hollow glass microspheres to the amount of the acid solution used for the acid etching is ≥1 g / mol.

[0062] In the embodiment of the present application, controlling the specific acid solution for acid etching and the ratio of the mass of the treated hollow glass microspheres to the amount of acid solution can promote the removal of K2O, Al2O3 and part of B2O3 impurities in the treated hollow glass microspheres by acid etching, thereby obtaining porous SiO2 particles and residual boron oxides, thereby facilitating the subsequent rapid heating to sublimate the residual boron oxides, and further obtaining pure porous amorphous SiO2 particles.

[0063] In actual use, the mass concentration of hydrochloric acid used for acid etching is generally 1M, and the amount of hydrochloric acid used for acid etching meets the requirement that at least 100ml of 1M hydrochloric acid is used for 1g of hollow glass microspheres.

[0064] Based on a general inventive concept, the present application provides an application of a method for preparing porous hollow silicon spheres using hollow glass microspheres, wherein the porous hollow silicon spheres obtained by the method are used to prepare battery negative electrode materials.

[0065] In the embodiment of the present application, the application is to use the obtained porous hollow silicon spheres as the negative electrode material of lithium-ion batteries after carbon coating to assemble into CR2025 button batteries. The specific steps are as follows:

[0066] Pure porous hollow silica spheres were mixed with 1 mol·L -1 The mixture was ultrasonicated at room temperature for 30 min, and aniline (C6H7N, analytical grade) was added according to wSi:wC6H7N=1:6, and magnetic stirring was performed at room temperature for 10 min.

[0067] Weigh the amount of ammonium persulfate ((NH4)2S2O8) and aniline and dissolve it in 1 mol·L -1 HCl solution was prepared to 0.5 mol·L -1 The ammonium persulfate solution was slowly added dropwise to the above-mentioned pure porous hollow silica sphere suspension under magnetic stirring at room temperature, and the magnetic stirring was continued at room temperature for 12 hours to obtain a dark green suspension.

[0068] 9600r·min -1After centrifugation, vacuum drying at 60℃ for 12h, and treatment at 1000℃ for 2h in a tube furnace under Ar flow, Si and C coated Si@C negative electrode material was obtained. The charge and discharge voltage range of the battery tester was set at 0.01V~2.0V (vs Li / Li + ), all the above tests were carried out at 25℃.

[0069] This application is implemented based on the above method. The specific steps of the method can refer to the above embodiments. Since this application adopts part or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0070] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0071] Example 1

[0072] like Figure 1 As shown, a method for preparing porous hollow silicon spheres using hollow glass microspheres comprises:

[0073] S1 is heated and kept warm for the hollow glass microspheres to undergo spinodal decomposition reaction to obtain SiO2 and other oxide microregions interspersed with the treated hollow glass microspheres;

[0074] S2. Acid-etch the treated glass hollow microspheres, filter them, and then rapidly heat them to 1500°C to obtain Figure 2 The porous amorphous SiO2 particles shown;

[0075] S3. Magnesium powder was added to the porous amorphous SiO2 particles and ball-milled, and then subjected to magnesium thermal reduction reaction under argon gas to obtain a mixture containing nano-silicon and magnesium oxide;

[0076] S4. Add the mixture to hydrochloric acid, rinse and filter, and then dry to obtain porous hollow silicon spheres.

[0077] Depend on Figure 2 It can be seen that the mantou peak near 22° indicates that the glass hollow microspheres are left with amorphous SiO2 particles after filtration.

[0078] The end point temperature T of the heating is 360°C.

[0079] The insulation time is 5h.

[0080] The endpoint temperature of the rapid heating is 1500°C.

[0081] The mass ratio of the porous amorphous SiO2 particles to the magnesium powder is 1:1.

[0082] The magnesium thermal reduction reaction includes a heating stage and a heat preservation stage. The terminal temperature of the heating stage is 550°C, and the time of the heat preservation stage is 6 hours.

[0083] The acid solution used for acid etching is hydrochloric acid, and the ratio of the mass of the processed glass hollow microspheres to the amount of the acid solution used for acid etching is ≥1 g / mol.

[0084] Example 2

[0085] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is:

[0086] The end point temperature T of the heating is 360°C.

[0087] The insulation time is 12h.

[0088] The endpoint temperature of the rapid heating is 1500°C.

[0089] The mass ratio of the porous amorphous SiO2 particles to the magnesium powder is 1:0.8.

[0090] The magnesium thermal reduction reaction includes a heating stage and a heat preservation stage. The terminal temperature of the heating stage is 660°C, and the time of the heat preservation stage is 4 hours.

[0091] Example 3

[0092] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is:

[0093] The end point temperature T of the heating is 360°C.

[0094] The insulation time is 24h.

[0095] The endpoint temperature of the rapid heating is 1500°C.

[0096] The mass ratio of the porous amorphous SiO2 particles to the magnesium powder is 1:0.9.

[0097] The magnesium thermal reduction reaction includes a heating stage and a heat preservation stage. The terminal temperature of the heating stage is 720°C, and the time of the heat preservation stage is 2 hours.

[0098] Example 4

[0099] Comparing Example 4 with Example 1, the difference between Example 4 and Example 1 is:

[0100] The end point temperature T of heating is 300°C.

[0101] The insulation time is 24h.

[0102] The endpoint temperature of the rapid heating is 1500°C.

[0103] The mass ratio of the porous amorphous SiO2 particles to the magnesium powder is 1:1.

[0104] The magnesium thermal reduction reaction includes a heating stage and a heat preservation stage. The terminal temperature of the heating stage is 660°C, and the time of the heat preservation stage is 4 hours.

[0105] Example 5

[0106] Comparing Example 5 with Example 1, the difference between Example 5 and Example 1 is:

[0107] The end point temperature T of heating is 400°C.

[0108] The insulation time is 5h.

[0109] The endpoint temperature of the rapid heating is 1500°C.

[0110] The mass ratio of the porous amorphous SiO2 particles to the magnesium powder is 1:1.

[0111] The magnesium thermal reduction reaction includes a heating stage and a heat preservation stage. The terminal temperature of the heating stage is 660°C, and the time of the heat preservation stage is 4 hours.

[0112] Comparative Example 1

[0113] Comparing Comparative Example 1 with Example 1, the difference between Comparative Example 1 and Example 1 is:

[0114] Only commercially available porous hollow silicon spheres were used as negative electrode materials for lithium-ion batteries after being coated with carbon and assembled into CR2025 button batteries.

[0115] Related experiments and effect data:

[0116] The assembled batteries obtained in each embodiment and comparative example were subjected to constant current charge and discharge tests using a battery tester to characterize their performance. The results are shown in Table 1.

[0117] Table 1 Performance of constant current charge and discharge of assembled batteries of various embodiments and comparative examples

[0118]

[0119] The electrochemical curves of the assembled batteries obtained in Comparative Example 1 and Example 1 after 400 cycles of constant current charge and discharge test are as follows: Figure 3 shown.

[0120] Depend on Figure 3It can be seen that the electrochemical cycle curve of the Si@C negative electrode prepared in Comparative Example 1 has a discharge capacity of 880.3 mAh·g after 400 cycles. -1 The capacity retention rate is 36.5%, while the electrochemical cycle curve of the Si@C negative electrode prepared by pure porous hollow silicon spheres still has a discharge capacity of 1117.7 mAh·g after 400 cycles. -1 , the capacity retention rate is 55.5%, showing excellent cycle stability and good electrochemical performance.

[0121] The XRD and N2 desorption-adsorption of the porous hollow silicon spheres obtained in Example 1 were tested. Figure 4 and Figure 5 shown.

[0122] Depend on Figure 4 It can be seen that the marked peak position is the significant peak position of crystalline Si, which indicates that only crystalline Si particles are left in the porous hollow silicon spheres after acid etching. Figure 5 There is an obvious hysteresis loop, indicating that the porous hollow silicon spheres have a porous structure.

[0123] The electrochemical performance of the assembled batteries obtained in each embodiment is shown in Table 1.

[0124] As can be seen from Table 1, the electrochemical performance of each embodiment is better than that of the comparative example after 4000 charge-discharge cycles in terms of discharge capacity, and the capacity retention rate is also better than that of the comparative example, demonstrating superior electrochemical performance.

[0125] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0126] (1) The embodiment of the present application provides a method for preparing porous hollow silicon spheres using hollow glass microspheres. Since the hollow glass microspheres, which are mature products of existing industrial chemical industry, are used as precursors, and then a simple magnesium thermal reduction process is used to replicate the porous hollow silicon spheres for lithium-ion battery negative electrodes, there is no need to separately design an expensive and complex Si precursor hollow sphere structure. Therefore, the overall production equipment is simple, the process is simple, and the production efficiency is high.

[0127] (2) The embodiment of the present application provides a method for preparing porous hollow silicon spheres using hollow glass microspheres. The obtained porous hollow silicon spheres not only have a high specific capacity and a stable spherical structure, but also the porous hollow structure formed plays a role in buffering the volume expansion of Si itself on the one hand; on the other hand, it also shortens the depth and diffusion distance of lithium ion deintercalation, so that it exhibits excellent and stable electrochemical performance.

[0128] (3) The present invention provides an application of a method for preparing porous hollow silicon spheres using hollow glass microspheres. The obtained porous hollow silicon spheres are applied to the negative electrode material of lithium-ion batteries. The structure is stable during the battery cycle, which is beneficial to improving the cycle life of lithium-ion batteries.

[0129] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0130] In this application, unless otherwise indicated, directional words such as "upper" and "lower" refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of this application specification, the terms "including" and "comprising" mean "including but not limited to".

[0131] In this document, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. In this document, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this document, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0132] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing porous hollow silicon spheres using hollow glass microspheres, characterized in that: The method comprises: Heating the hollow glass microspheres and keeping them warm to cause a spinodal decomposition reaction, thereby obtaining treated hollow glass microspheres in which SiO2 and other oxide microregions are alternately distributed; Acid etching the treated glass hollow microspheres, filtering them, and then rapidly heating them to obtain porous amorphous SiO2 particles; Adding magnesium powder to the porous amorphous SiO2 particles, ball milling, and then performing a magnesium thermal reduction reaction in an oxygen-free environment to obtain a mixture containing nano-silicon and magnesium oxide; adding the mixture to hydrochloric acid, rinsing and filtering, and then drying to obtain porous hollow silicon spheres; The particle size of the hollow glass microspheres is 10 μm to 30 μm, and the wall thickness of the hollow glass microspheres is 1 μm to 2 μm; The mass ratio of the porous amorphous SiO2 particles to the magnesium powder is ≥1; The ball milling time is ≥2h; the particle size of the magnesium powder is ≤30μm; The acid solution used for the acid etching is hydrochloric acid, and the ratio of the mass of the treated hollow glass microspheres to the amount of the acid solution used for the acid etching is ≥1 g / mol.

2. The method according to claim 1, characterized in that The end temperature T of the heating satisfies: 0.85Ts≤T≤Ts, Wherein, Ts is the stable temperature of the spinodal decomposition reaction.

3. The method according to claim 1, characterized in that The insulation time is 1 hour to 24 hours.

4. The method according to claim 1, wherein The endpoint temperature of the rapid heating is ≥1500°C.

5. The method according to claim 1, characterized in that The magnesium thermal reduction reaction includes a heating stage and a heat preservation stage. The terminal temperature of the heating stage is 500° C. to 800° C., and the time of the heat preservation stage is 2 hours to 6 hours.

6. An application of a method for preparing porous hollow silicon spheres using hollow glass microspheres, characterized in that: The application is to use the porous hollow silicon spheres obtained by the method according to any one of claims 1 to 5 to prepare battery negative electrode materials.

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