Multi-stage structure silicon-based negative electrode material, modified silicon-based negative electrode material, preparation and application

Abstract

The application discloses a kind of multistage structure silicon-based negative materials, modified silicon-based negative materials and preparation, application.The preparation method of the multistage structure silicon-based negative material includes the following steps: silicon aerogel and pre-magnesium silicon particles are immersed in carbon aerogel precursor, and are prepared by aging, pyrolysis;Wherein, the raw material for preparing the carbon aerogel precursor includes acrylic acid and polyvinylpyrrolidone, and the mass ratio of the acrylic acid and the polyvinylpyrrolidone is (0.5-15):1.The multistage structure silicon-based negative material prepared by the application has abundant porous structure, improves the limited contact area between silicon-carbon composite material, promotes lithium ion migration rate in charge and discharge process, so that the electrochemical performance of the multistage structure silicon-based negative material is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a multi-level structure silicon-based negative electrode material, a modified silicon-based negative electrode material and preparation and application thereof. BACKGROUND

[0002] Lithium-ion batteries have become one of the key components of portable devices, especially in mobile phones, digital cameras, notebook computers and electric vehicles, due to their high energy density and long cycle life. However, with the increasing global demand for lithium-ion batteries, there are bottlenecks in energy density, safety and life. At present, negative electrode materials with high specific capacity and excellent rate performance are the key to improving the energy density of lithium-ion batteries. Compared with traditional commercial graphite (372 mAh·g -1 ), silicon (Si) has great potential and is widely studied due to its unique high specific capacity (4200 mAh·g -1 ), low operating voltage, high charge-discharge cycleability, high rate performance, sufficient safety, low cost, environmental protection, high stability and scalability. It has played a crucial role in promoting the rapid development of portable electronic devices. However, silicon-based negative electrode electrodes have certain limitations, such as low electrical conductivity, large volume fluctuation (300%) during electrochemical operation, which leads to rapid capacity degradation and low performance. In the process of de-lithiation / intercalation, the volume of silicon inevitably expands and shrinks greatly, causing material pulverization, and then continuously forming an unstable SEI film, leading to electrolyte depletion to form a solid electrolyte, which will eventually accelerate capacity decay and seriously affect cycle stability. In addition, the inherent low conductivity of silicon seriously hinders its practical application.

[0003] To effectively alleviate these problems, it is urgent to develop a silicon-based anode with stable structure and improved electrochemical performance by changing the morphology and structure of silicon. The most effective method is to reasonably design silicon-based materials with unique structures, such as nano-silicon, porous silicon and silicon-carbon composite materials. Studies have shown that nano-silicon particles can significantly reduce the mechanical strain caused by volume change and maintain the structural integrity of the material, thereby improving the cycle stability of silicon. The enhancement of cycle stability is due to the increase of specific surface area, the shortening of lithium ion diffusion path and the existence of a large number of pores in the nanostructure. The preparation of silicon nanomaterials usually uses liquid phase method or chemical vapor deposition (CVD) method, which usually involves toxic silane gas and has low yield, limiting their practical application. The thermal reduction of Mg has been of particular interest, SiO2 can be reduced to Si by magnesium thermal reduction reaction: SiO2(s) + 2Mg(g) → Si(s) + 2MgO(s), which provides a simple, large-scale and environmentally friendly method for the synthesis of silicon nanomaterials. However, a large number of literature and commercial research have shown that a portion of magnesium elements in the pre-magnesium silicon particles still cannot be completely reacted with silicon, which also affects the actual battery capacity of the pre-magnesium silicon-based anode material. At the same time, there is no research content on the remaining magnesium problem of pre-magnesium.

[0004] To make the silicon-based anode material have better cycle stability and rate performance, in addition to preparation by magnesium thermal reduction, carbon materials can also be selected as stress buffer substrates on this basis to adapt to the larger volume change during silicon lithiation, while improving the electrical conductivity. Carbon materials have excellent structural stability and electrochemical activity, and good compatibility with silicon materials can promote the formation of composite materials. In this new type of composite material, silicon particles provide sufficient specific capacity, and carbon materials inhibit the volume expansion effect of the composite material. The two form a three-dimensional interpenetrating conductive network, which helps to improve the cycle performance and high-rate performance of the silicon-based anode. However, traditional carbon materials usually use an external coating method for silicon-carbon composites, which also leads to poor dispersion between silicon and carbon, and the contact area between the two is limited, which cannot fully exert the performance of silicon-carbon composite materials.

[0005] Patent CN116169256A provides a preparation method of a silicon-carbon negative electrode material. The method uses silica aerogel material as the substrate, combines with the fluidized bed reactor, and passes in silane gas for chemical deposition and gas fluidization process to obtain a silicon-carbon negative electrode material after coating the surface with nano-silicon. Although this patent improves the volume expansion and electrochemical performance of the material, the content of the carbon material coating layer is not easy to control, and the chemical vapor deposition method used has high cost, involves high temperature and toxic silane gas, and has problems such as low yield, high danger and difficult control, which limits their practical application.

[0006] Patent CN116573647A provides a preparation method of a porous silicon-carbon negative material based on a silicon aerogel structure. By adjusting the co-gelation of tetraethyl orthosilicate and phenolic resin, and then through freeze-drying and high-temperature reduction carbonization treatment, a silicon-carbon composite three-dimensional nano-porous structure material is prepared. The carbon material is introduced while the porous structure is constructed. Although the carbon composite process is improved, the vacuum freeze-drying method used in the patent is complex and has high cost. Moreover, the first coulombic efficiency is low and the electrochemical performance such as charge and discharge capacity is poor, which still has a large gap from practical application.

[0007] Therefore, it is urgent to develop a silicon-based negative electrode material that can solve the problem of residual magnesium after pre-magnification, while also having high capacity, high first efficiency, and low expansion rate. SUMMARY

[0008] The technical problem to be solved by the present application is the poor performance of the silicon-based negative electrode material in the prior art. The present application provides a multi-level structure silicon-based negative electrode material, a modified silicon-based negative electrode material, and a preparation and application thereof. The multi-level structure silicon-based negative electrode material prepared by the present application has a rich porous structure, which improves the limited contact area between the silicon-carbon composite material and promotes the lithium ion migration rate during the charging and discharging process, thereby greatly improving the electrochemical performance of the multi-level structure silicon-based negative electrode material.

[0009] The present application solves the above technical problems by the following technical solutions.

[0010] The present application provides a preparation method of a multi-level structure silicon-based negative electrode material, which comprises the following steps: immersing silicon aerogel and pre-magnesium silicon particles in a carbon aerogel precursor, and then aging and pyrolyzing to obtain the multi-level structure silicon-based negative electrode material.

[0011] The raw materials for preparing the carbon aerogel precursor include acrylic acid (PAA) and polyvinylpyrrolidone (PVP), and the mass ratio of the acrylic acid to the polyvinylpyrrolidone is (0.5-15):1.

[0012] In the present application, the particle size D50 of the silicon aerogel can be 7-11 μm, for example, 9.5 μm, 10 μm, or 10.3 μm.

[0013] In the present application, the silicon aerogel has a three-dimensional structure. The silicon aerogel can be prepared by a conventional sol-gel method; preferably, a silicon source is hydrolyzed, polycondensed, aged, and sintered to obtain the silicon aerogel.

[0014] The silicon source can be an inorganic silicon source and / or an organic silicon source.

[0015] The inorganic silicon source can be selected from one or more of silicon tetrachloride, water glass and silica sol, for example silica sol. Preferably, the silica sol can have a concentration of 15-25%, for example 20%. The silica sol can be purchased from Beijing Institute of Aeronautical Materials.

[0016] The organic silicon source can be selected from one or more of tetraethyl orthosilicate (tetraethyl orthosilicate), methyl orthosilicate and alkoxysilane, for example tetraethyl orthosilicate.

[0017] When the organic silicon source is used, a dispersant can also be added. The dispersant can be cetyltrimethylammonium bromide (CTAB) and / or polyethylene glycol. The above dispersants have a large number of hydroxyl groups, which are beneficial to promote the bonding and bonding between the silicon sources.

[0018] The hydrolysis can be performed by adding an acid. Preferably, the acid is selected from one or more of hydrochloric acid, oxalic acid, acetic acid, nitric acid and sulfuric acid, for example acetic acid.

[0019] Preferably, the pH of the system is adjusted to 3-4, for example 3.5, after adding the acid.

[0020] Preferably, stirring is also performed after adding the acid. The stirring time can be 2-4h, for example 3h.

[0021] The polycondensation can be performed by adding a basic substance. Preferably, the basic substance is selected from one or more of sodium hydroxide, sodium carbonate and ammonia, for example ammonia.

[0022] Preferably, the pH of the solution is adjusted to 9-10, for example 9.5, after adding the basic substance.

[0023] Preferably, stirring is also performed after adding the basic substance. The stirring time can be 15-40min, for example 30min.

[0024] The aging temperature can be 40-70℃, for example 55℃.

[0025] The aging time can be 9-14h, for example 10h.

[0026] When the inorganic silicon source is used, the sintering temperature can be 300-400℃, for example 350℃.

[0027] When the inorganic silicon source is used, the sintering time can be 4-6h, for example 5h.

[0028] When the organic silicon source is used, the sintering temperature can be 500-800℃, for example 600℃.

[0029] When the organic silicon source is used, the sintering time can be 0.5-5h, for example, 2h. In the present application, the material realizes the crystallization transformation of silicon during the sintering process.

[0030] In the present application, the chemical formula of the pre-magnesium silicon particles can be SiMg y O x , wherein 1≤y≤2, 3≤x≤4.

[0031] In the present application, the particle size D50 of the pre-magnesium silicon particles can be 4-7μm, for example, 5.5μm or 5.7μm.

[0032] In the present application, preferably, the pre-magnesium silicon particles are prepared by heat treating a mixture of a silicon oxide source and metallic magnesium; the silicon oxide source is silicon dioxide and / or silicon monoxide.

[0033] Preferably, the silicon oxide source is silicon dioxide / silicon monoxide. Since silicon monoxide and silicon dioxide are often difficult to store alone and can be converted into each other, the present application can directly use a mixture of silicon dioxide and silicon monoxide as raw material.

[0034] Preferably, the mass ratio of the silicon oxide source to the metallic magnesium can be 500:(30-80), for example, 500:50.

[0035] Preferably, the mixture can be prepared by manually mixing the raw materials or mixing in a fusion machine, a VC mixing machine or a ball mill.

[0036] Preferably, the temperature of the heat treatment can be 500-1200℃, for example, 950℃. The present application uses a heat treatment process to change the crystal structure of the mixture.

[0037] Preferably, the time of the heat treatment can be 13-18h, for example, 16h.

[0038] In the present application, the mass ratio of the silicon aerogel to the pre-magnesium silicon particles can be 1:(0.5-2), for example, 1:1.

[0039] In the present application, the mass ratio of the acrylic acid to the polyvinylpyrrolidone is preferably (0.5-10):1, for example, 1:2, 4:1 or 9:1.

[0040] In the present application, the mass-volume ratio of the silicon aerogel to the carbon aerogel precursor can be 1mg:(1-2)mL, for example, 50mg:100mL.

[0041] In the present application, the carbon aerogel precursor can be prepared by mixing an acrylic acid solution and the polyvinylpyrrolidone. The carbon aerogel precursor is in sol state.

[0042] The concentration of the acrylic acid solution can be 40% or 60%. The acrylic acid solution can be purchased from Shanghai Jiyisheng Chemical Technology Co., Ltd.

[0043] When the concentration of the acrylic acid solution is 40%, the mass-volume ratio of polyvinylpyrrolidone in the polyvinylpyrrolidone solution to the acrylic acid solution can be (100-300) mg:1 mL, for example, 40 mg:0.4 mL or 80 mg:0.4 mL.

[0044] When the concentration of the acrylic acid solution is 60%, the mass-volume ratio of polyvinylpyrrolidone in the polyvinylpyrrolidone solution to the acrylic acid solution can be (50-200) mg:1 mL, for example, 40 mg:0.6 mL.

[0045] In the present application, the impregnation time can be 1-3 h, for example, 2 h.

[0046] In the present application, the aging temperature can be 30-80℃, for example, 55℃.

[0047] In the present application, the pyrolysis temperature can be 200-600℃, for example, 350℃.

[0048] In the present application, the pyrolysis time can be 30-300 min, for example, 90 min.

[0049] The present application also provides a multi-level structure silicon-based negative electrode material prepared by the above preparation method.

[0050] In the present application, the particle size D50 of the multi-level structure silicon-based negative electrode material can be 50-90 μm, preferably 50-60 μm, for example, 54 μm, 55 μm, 57 μm or 59 μm.

[0051] In the present application, the particle size D50 of the carbon aerogel in the multi-level structure silicon-based negative electrode material can be 50-90 μm, for example, 50 μm.

[0052] In the present application, from different dimensional perspectives, the multi-level structure refers to a multi-dimensional hierarchical structure composed of one-dimensional, two-dimensional and three-dimensional structure materials; from a spatial perspective, the multi-level structure refers to a multi-level hierarchical structure composed of an inner support layer, an intermediate embedded layer and an outer support layer.

[0053] The present application also provides a modified silicon-based negative electrode material, which has a structure like a sea urchin, with silicon aerogel and carbon aerogel as inner and outer supports, respectively, and silica / silicon monoxide particles embedded therein.

[0054] In the present application, the particle size of the modified silicon-based negative electrode material can be 50-90 μm, preferably 50-70 μm, 56 μm, 57 μm, 59 μm, 63 μm, 64 μm or 69 μm.

[0055] In the present application, the particle size of the carbon aerogel can be 40-60 μm, for example 49 μm, 50 μm, 51 μm or 53 μm.

[0056] The present application also provides a preparation method of a modified silicon-based negative electrode material, which comprises the following steps: heating a mixture of the above-mentioned multi-level structure silicon-based negative electrode material and a modifier to obtain the modified silicon-based negative electrode material; the modifier comprises a multi-dimensional material.

[0057] In the present application, the mass ratio of the multi-level structure silicon-based negative electrode material to the modifier can be (1-5):1, for example 1.29:1, 2:1 or 2.5:1.

[0058] In the present application, the multi-dimensional material can be a zero-dimensional structure material, a one-dimensional structure material, a two-dimensional structure material or a three-dimensional structure material.

[0059] The zero-dimensional structure material can be selected from carbon dots.

[0060] The one-dimensional structure material can be selected from silicon nanotubes and / or carbon nanotubes. The diameter of the silicon nanotube can be 50-70 nm, for example 60 nm.

[0061] The two-dimensional structure material can be selected from one or more of MoS2, MXene and graphene. The MoS2 can be prepared by mixing sodium molybdate, thiourea and cetyltrimethylammonium bromide.

[0062] The three-dimensional structure material can be selected from cage-type polyhedral oligomeric silsesquioxane (POSS) and / or graphite. The cage-type polyhedral oligomeric silsesquioxane (POSS) can be prepared by mixing vinyl POSS, dichloromethane and ammonium sulfate.

[0063] In the present application, the modifier can further comprise a phosphorus-containing compound. The phosphorus-containing compound can be (NH4)2HPO4. In a preferred embodiment, the modifier comprises silicon nanotubes and (NH4)2HPO4.

[0064] The mass ratio of the phosphorus-containing compound to the multi-dimensional material can be 1:(3-5), for example 1:4.

[0065] When the modifier further comprises a phosphorus-containing compound, the modifier can be prepared by the following steps: dissolving the multi-dimensional material and the phosphorus-containing compound in a solvent, heating, drying and calcining.

[0066] The solvent can be deionized water.

[0067] The heating temperature can be 40-50℃, for example 45℃.

[0068] The heating time can be 20-60min, for example 30min.

[0069] The calcination temperature can be 400-600℃, for example 500℃.

[0070] The calcination time can be 400-600℃, for example 2h.

[0071] During the calcination, the rate of temperature rise to the calcination temperature can be 1-10℃ / min, for example 5℃ / min.

[0072] In the present application, the heating temperature can be 70-90℃, for example 80℃.

[0073] In the present application, the heating time can be 4-6h, for example 5h.

[0074] In the present application, the heating can further comprise annealing.

[0075] The annealing temperature can be 700-900℃, for example 700℃ or 850℃.

[0076] The annealing time can be 1-3h, for example 2h.

[0077] The present application also provides a modified silicon-based negative electrode material prepared by the above preparation method.

[0078] In the present application, the particle size of the modified silicon-based negative electrode material can be 50-90μm, preferably 50-70μm, 56μm, 57μm, 59μm, 63μm, 64μm or 69μm.

[0079] In the present application, the particle size of the carbon aerogel in the modified silicon-based negative electrode material can be 40-60μm, for example 49μm, 50μm, 51μm or 53μm.

[0080] The present application also provides a use of the above multi-level structure silicon-based negative electrode material or the above modified silicon-based negative electrode material in a battery.

[0081] In the present application, the battery is preferably a lithium ion battery.

[0082] On the basis of common general knowledge in the art, the above preferred conditions can be combined arbitrarily, i.e. to obtain each preferred example of the present application.

[0083] The reagents and raw materials used in the present application are commercially available.

[0084] The positive progress effect of the present application is that:

[0085] (1) The present application has a double support structure and a three-dimensional frame structure of sea urchin shape on the outside by co-impregnating silicon aerogel and pre-magnesium silicon particles in a carbon source sol. The multi-level structure silicon-based negative electrode material prepared by the present application has a rich porous structure, greatly alleviates the volume expansion rate of silicon during the charging and discharging process, realizes the uniform dispersion of nano-silicon-based materials and carbon materials of different dimensions, improves the limited contact area between silicon-carbon composite materials, and promotes the lithium ion migration rate during the charging and discharging process, thereby greatly improving the electrochemical performance of the multi-level structure silicon-based negative electrode material.

[0086] (2) Further, the present application also uses multi-dimensional materials to modify the materials, which not only greatly improves the thermal stability of the product, but also further increases the specific surface area of the composite system and optimizes the battery capacity under the condition of avoiding the collapse of the aerogel frame. BRIEF DESCRIPTION OF DRAWINGS

[0087] Figure 1 The structure diagram of the silicon-based negative electrode material prepared by the present application. DETAILED DESCRIPTION

[0088] The present application will be further described by way of examples, but the present application is not limited in the scope of the examples. The experimental methods not specified in the following examples are selected according to the conventional methods and conditions, or according to the product instructions.

[0089] In the examples and comparative examples of the present application, the silica sol (concentration 20%) was purchased from Beijing Aeronautical Materials Research Institute; polyvinylpyrrolidone (PVP, K30, average molecular weight 58000), tetraethyl orthosilicate (98%), cetyltrimethylammonium bromide (CTAB, 99%) and polyethylene glycol (Mn 1500) were purchased from Shanghai Aladdin Reagent Co., Ltd.; 40% and 60% concentration polyacrylic acid (PAA) solutions were purchased from Shanghai Jizisheng Biotechnology Co., Ltd.; the silicon nanotubes (diameter 60 nm) were purchased from Shandong Silica New Material Technology Co., Ltd.; the silicon dioxide / silicon monoxide raw material (LK25) was purchased from Shandong Lianke Technology Co., Ltd.; vinyl POSS (95%), (NH4)2HPO4, acetic acid (60%) and other raw materials were purchased from National Pharmaceutical Reagent.

[0090] Example 1

[0091] (1) To the silicon sol of 20% concentration, add equal amount of acetic acid to adjust the pH of the system to about 3.5, stir for 3h to hydrolyze, then adjust the pH of the silicon sol with ammonia water to 9.5, stir for 30min, then transfer the silicon sol to an oil bath pot at 55℃ for constant temperature aging for 10h, after the silicon sol is converted into a gel state, heat at 350℃ for 5h to obtain a silicon aerogel with a D50 of 9.5μm;

[0092] (2) Take the silicon dioxide / silicon monoxide raw material and magnesium powder with a mass ratio of 500:50, mechanically mix by ball milling, and the magnesium powder is used to modify the silicon particles during the mixing process; then heat treat at 950℃ for 16h to obtain pre-magnesium silicon particles with a D50 of 5.7μm;

[0093] (3) Dissolve 80mg of PVP in 50mL of deionized water and stir for 15min, then add 0.4mL of 40% polyacrylic acid aqueous solution and stir for 15min (PAA and PVP solute mass ratio is 1:2), then add deionized water to prepare 100mL of sol solution and stir thoroughly for 30min. Using the immersion method, take 50mg of the silicon aerogel prepared in step (1) and the pre-magnesium silicon particles prepared in step (2) and add them into the sol solution to mix and immerse for 2h, then dry by low temperature aging at 55℃ to dryness, and pyrolyze at 350℃ for 90min to obtain hierarchical aerogel-silicon-based nanoparticles (i.e. multi-level structure silicon-based anode material) with a D50 of 54μm;

[0094] (4) Take 20mg of silicon nanotubes and 5mg of (NH4)2HPO4 and dissolve them in 50mL of deionized water, stir thoroughly at 45℃ for 30min, dry and grind, and heat at 500℃ for 2h with a heating rate of 5℃ / min to obtain P-doped-silicon nanotubes. Then using the hydrothermal method, take 50mg of the aerogel-silicon-based nanoparticles prepared in step (3) and 5mg of P-doped-silicon nanotubes, and hydrothermally treat at 80℃ for 5h to realize surface deposition modification, and then anneal at 850℃ for 2h to obtain a modified silicon-based anode material. In the modified silicon-based anode material, the particle size D50 of the carbon aerogel is 49μm, and the particle size D50 of the composite material (modified silicon-based anode material) is 56μm.

[0095] Example 2

[0096] (1) To the 20% concentration of silica sol, add equal amount of acetic acid to adjust the pH of the system to about 3.5, stir for 3h, hydrolysis, then adjust the pH of the silica sol with ammonia water, adjust the pH to 9.5, stir for 30min, then transfer the silica sol to a 55℃ oil bath pot for constant temperature aging for 10h, after the silica sol is converted into gel state, heat at 350℃ for 5h and take out, get the D50 of 9.5μm of silica aerogel;

[0097] (2) Take the silica / silicon monoxide raw material and magnesium powder with a mass ratio of 500:50, mechanically mix by ball milling, the magnesium powder modifies the silicon particles during the mixing process; then heat treat at 950℃ for 16h to obtain D50 of 5.7μm of pre-magnesium silicon particles;

[0098] (3) Dissolve 40mg of PVP in 50mL of deionized water and stir for 15min, then add 0.4mL of 40% concentration of polyacrylic acid aqueous solution and stir for 15min (PAA and PVP solute mass ratio is 4:1), then add deionized water to mix and prepare 100mL of sol solution, and stir fully for 30min. Using the immersion method, take 50mg of the silica aerogel prepared in step (1) and the pre-magnesium silicon particles prepared in step (2) and add them to the sol solution to mix and immerse for 2h, then dry by low temperature aging at 55℃ to dryness, pyrolyze at 350℃ for 90min to obtain D50 of 55μm of hierarchical aerogel-silicon-based nanoparticles (i.e. multi-level structure silicon-based anode material);

[0099] (4) Take 20mg of silicon nanotubes and 5mg of (NH4)2HPO4 and dissolve them in 50mL of deionized water, stir fully at 45℃ for 30min, dry and grind, and heat at 500℃ for 2h with a heating rate of 5℃ / min to obtain P-doped-silicon nanotubes. Then using the hydrothermal method, take 50mg of the aerogel-silicon-based nanoparticles prepared in step (3) and 5mg of P-doped-silicon nanotubes, and hydrothermally treat at 80℃ for 5h to realize surface deposition modification, and then anneal at 850℃ for 2h to obtain the modified silicon-based anode material. In the modified silicon-based anode material, the particle size D50 of the carbon aerogel is 51μm, and the particle size D50 of the composite material (modified silicon-based anode material) is 57μm.

[0100] Example 3

[0101] (1) To the silicon sol of 20% concentration, add equal amount of acetic acid to adjust the pH of the system to about 3.5, stir for 3h to hydrolyze, then adjust the pH of the silicon sol with ammonia water to 9.5, stir for 30min, then transfer the silicon sol to an oil bath pot at 55℃ for constant temperature aging for 10h, after the silicon sol is converted into a gel state, heat at 350℃ for 5h to obtain a silicon aerogel with a D50 of 9.5μm;

[0102] (2) Take the silicon dioxide / silicon monoxide raw material and magnesium powder with a mass ratio of 500:50, mechanically mix by ball milling, and the magnesium powder is used to modify the silicon particles during the mixing process; then heat treat at 950℃ for 16h to obtain pre-magnesium silicon particles with a D50 of 5.7μm;

[0103] (3) Dissolve 40mg of PVP in 50mL of deionized water and stir for 15min, then add 0.6mL of 60% polyacrylic acid aqueous solution and stir for 15min (PAA to PVP solute mass ratio is 9:1), then add deionized water to prepare 100mL of sol solution and stir thoroughly for 30min. Using the immersion method, take 50mg of the silicon aerogel prepared in step (1) and the pre-magnesium silicon particles prepared in step (2) and add them to the sol solution to mix and immerse for 2h, then evaporate to dryness at 55℃, and pyrolyze at 350℃ for 90min to obtain hierarchical aerogel-silicon-based nanoparticles (i.e. multi-level structure silicon-based anode material) with a D50 of 57μm;

[0104] (4) Take 20mg of silicon nanotubes and 5mg of (NH4)2HPO4 and dissolve them in 50mL of deionized water, stir thoroughly at 45℃ for 30min, dry and grind, and heat at 500℃ for 2h with a heating rate of 5℃ / min to obtain P-doped-silicon nanotubes. Then using the hydrothermal method, take 50mg of the aerogel-silicon-based nanoparticles prepared in step (3) and 5mg of P-doped-silicon nanotubes, and hydrothermally treat at 80℃ for 5h to realize surface deposition modification, and then anneal at 850℃ for 2h to obtain a modified silicon-based anode material. In the modified silicon-based anode material, the particle size D50 of the carbon aerogel is 53μm, and the particle size D50 of the composite material (modified silicon-based anode material) is 59μm.

[0105] Example 4

[0106] (1) 15 mL of tetraethyl orthosilicate, 20 mmol / L of cetyltrimethylammonium bromide (CTAB), and 80 mg of polyethylene glycol were dissolved in 100 mL of deionized water, and continuously stirred at 45°C for 30 min until fully dissolved and dispersed. Acetic acid was added dropwise to the system to adjust the pH of the system to 3.5, and hydrolyzed for 6 h to form a SiO2 sol. Then the pH value was adjusted using ammonia water to 9.5, and after stirring for 30 min, the sol was moved to an oil bath at 55°C for constant temperature aging for 10 h to obtain a white suspension. The white suspension was centrifuged and washed three times, and then taken out after high-temperature calcination at 600°C for 2 h to obtain silicon aerogel with a particle size D50 of 10.3 μm;

[0107] (2) The silica / silicon monoxide raw material was mixed with magnesium powder at a mass ratio of 500:50, and mechanical mixing was performed by ball milling. During the mixing process, the magnesium powder modified the silicon particles. Then, the mixture was subjected to high-temperature heat treatment at 950°C for 16 h to obtain pre-magnesium silicon particles with a particle size D50 of 5.7 μm;

[0108] (3) 40 mg of PVP was dissolved in 50 mL of deionized water and stirred for 15 min, then 0.4 mL of 40% polyacrylic acid aqueous solution was added and stirred for 15 min (PAA and PVP solute mass ratio was 4:1), then deionized water was added to prepare 100 mL of sol solution, and fully stirred for 30 min. Using the immersion method, 50 mg of the silicon aerogel prepared in step (1) and 50 mg of the pre-magnesium silicon particles prepared in step (2) were added to the sol solution and fully mixed and immersed for 2 h, then dried by low-temperature aging at 55°C, and pyrolyzed at 350°C for 90 min to obtain hierarchical aerogel-silicon-based nanoparticles (i.e. multi-level structure silicon-based anode material) with a particle size D50 of 59 μm;

[0109] (4) 20 mg of silicon nanotubes and 5 mg of (NH4)2HPO4 were dissolved in 50 mL of deionized water, and fully stirred at 45°C for 30 min. After drying and grinding, the mixture was heated at 500°C for 2 h at a heating rate of 5°C / min to obtain P-doped-silicon nanotubes. Then, using a hydrothermal method, 50 mg of the aerogel-silicon-based nanoparticles prepared in step (3) and 5 mg of the P-doped-silicon nanotubes were subjected to hydrothermal treatment at 80°C for 5 h to achieve surface deposition modification, and then annealed at 850°C for 2 h to obtain a modified silicon-based anode material. In the modified silicon-based anode material, the particle size D50 of the carbon aerogel was 51 μm, and the particle size D50 of the composite material (modified silicon-based anode material) was 63 μm.

[0110] Example 5

[0111] (1) To the silicon sol of 20% concentration, add equal amount of acetic acid to adjust the pH of the system to about 3.5, stir for 3h for hydrolysis, then adjust the pH of the silicon sol with ammonia water to 9.5, stir for 30min, then transfer the silicon sol to an oil bath at 55℃ for constant temperature aging for 10h, after the silicon sol is converted into gel state, heat at 350℃ for 5h and then take out, to obtain silicon aerogel with D50 of 9.5μm;

[0112] (2) Take the silicon dioxide / silicon monoxide raw material and mix with magnesium powder in a mass ratio of 500:50, mechanically mix by ball milling method, the magnesium powder performs metal modification on the silicon particles during the mixing process; then heat treat at high temperature of 950℃ for 16h to obtain pre-magnesium silicon particles with D50 of 5.7μm;

[0113] (3) Dissolve 40mg of PVP in 50mL of deionized water and stir for 15min, then add 0.4mL of polyacrylic acid aqueous solution with a concentration of 40% and stir for 15min (PAA and PVP solute mass ratio is 4:1), then add deionized water to mix and prepare 100mL of sol solution, and fully stir for 30min. Using the impregnation method, take 50mg of the silicon aerogel prepared in step (1) and the pre-magnesium silicon particles prepared in step (2) respectively, add to the sol solution and fully mix and impregnate for 2h, then low-temperature age at 55℃ to evaporate to dryness, high-temperature pyrolysis at 350℃ for 90min to obtain hierarchical aerogel-silicon-based nanoparticles (i.e. multi-level structure silicon-based anode material) with D50 of 55μm;

[0114] (4) Take 0.2g of vinyl POSS and dissolve in 10mL of dichloromethane, add 1mL of ammonium sulfate (APS), after the mixed solution is stirred at room temperature for 15h, the precursor of cage-like polyhedral oligomeric silsesquioxane POSS is obtained, then add 0.5g of hierarchical aerogel-silicon-based nanoparticles for 2h of impregnation modification, then add 50mL of methanol to precipitate the solid, after filtration, washing, and drying in a 45℃ oven overnight, the modified silicon-based anode material is obtained. In the modified silicon-based anode material, the particle size D50 of the carbon aerogel is 50μm, and the particle size D50 of the composite material (modified silicon-based anode material) is 69μm.

[0115] Example 6

[0116] (1) To the silicon sol of 20% concentration, add equal amount of acetic acid to adjust the pH of the system to about 3.5, stir for 3h for hydrolysis, then adjust the pH of the silicon sol with ammonia water to 9.5, stir for 30min, then transfer the silicon sol to an oil bath at 55℃ for constant temperature aging for 10h, after the silicon sol is converted into gel state, heat at 350℃ for 5h and then take out, to obtain silicon aerogel with D50 of 9.5μm;

[0117] (2) Take the silicon dioxide / silicon monoxide raw material and magnesium powder with a mass ratio of 500:50, mechanically mix them by using the ball milling method, and the magnesium powder performs metal modification on the silicon particles during the mixing process; then, place them in a high-temperature heat treatment at 950℃ for 16h, to obtain pre-magnesium silicon particles with a D50 of 5.7μm;

[0118] (3) Dissolve 40mg of PVP in 50mL of deionized water and stir for 15min, then add 0.4mL of a 40% concentration polyacrylic acid aqueous solution and stir for 15min (the mass ratio of PAA to PVP solute is 4:1), then add deionized water to mix and prepare 100mL of a sol solution, and fully stir for 30min. Using the immersion method, take 50mg of the silicon aerogel prepared in step (1) and the pre-magnesium silicon particles prepared in step (2), add them to the sol solution and fully mix and immerse for 2h, evaporate to dryness after low-temperature aging at 55℃, and pyrolyze at 350℃ for 90min, to obtain hierarchical aerogel-silicon-based nanoparticles (i.e. multi-level structure silicon-based negative electrode material) with a D50 of 55μm;

[0119] (4) Take 50mg of sodium molybdate, 10mg of thiourea, and 15mg of cetyltrimethylammonium bromide (CTAB) and dissolve them in 100mL of deionized water to prepare a precursor solution of MoS2. Using the hydrothermal method, take 50mg of the hierarchical aerogel-silicon-based nanoparticles prepared in step (3) and place them in the solution, then move them to a 65℃ constant-temperature oil bath for 12h, to hydrothermally co-deposit and grow MoS2 nanosheet particles, after multiple centrifugation, washing, and drying, perform 700℃ annealing treatment for 2h, to obtain a modified silicon-based negative electrode material. In the modified silicon-based negative electrode material, the particle size D50 of the carbon aerogel is 50μm, and the particle size D50 of the composite material (modified silicon-based negative electrode material) is 64μm.

[0120] Example 7

[0121] (1) Add an equal amount of acetic acid to a 20% concentration silica sol, adjust the pH of the system to about 3.5, and stir for 3h to perform hydrolysis, then use ammonia water to adjust the pH value of the silica sol to 9.5, stir for 30min, then transfer the silica sol to a 55℃ oil bath for constant-temperature aging for 10h, after the silica sol is converted into a gel state, take it out after heating at 350℃ for 5h, to obtain silicon aerogel with a D50 of 9.5μm;

[0122] (2) Take the silicon dioxide / silicon monoxide raw material and magnesium powder with a mass ratio of 500:50, mechanically mix them by using the ball milling method, and the magnesium powder performs metal modification on the silicon particles during the mixing process; then, place them in a high-temperature heat treatment at 950℃ for 16h, to obtain pre-magnesium silicon particles with a D50 of 5.7μm;

[0123] (3) 40 mg PVP was dissolved in 50 mL of deionized water and stirred for 15 min, then 0.4 mL of a 40% polyacrylic acid aqueous solution was added and stirred for 15 min (the mass ratio of PAA to PVP solute was 4:1), then deionized water was added to prepare 100 mL of sol solution, and fully stirred for 30 min. Using the immersion method, 50 mg of the silicon aerogel prepared in step (1) and the pre-magnesium silicon particles prepared in step (2) were added to the sol solution and fully mixed and immersed for 2 h, then aged at a low temperature of 55°C until evaporated to dryness, and pyrolyzed at a high temperature of 350°C for 90 min to obtain hierarchical aerogel-silicon-based nanoparticles (i.e. multi-level structure silicon-based negative electrode material) with a D50 of 55 μm.

[0124] Comparative Example 1

[0125] (1) The silicon dioxide / silicon monoxide raw material was mixed with magnesium powder at a mass ratio of 500:50, and mechanical mixing was performed using a ball milling method. During the mixing process, the magnesium powder performed metal modification on the silicon particles. Then, high-temperature heat treatment was performed at 950°C for 16 h to obtain pre-magnesium silicon particles with a D50 of 5.7 μm.

[0126] (2) Equal amount of acetic acid was added to the 20% concentration silicon sol to adjust the pH of the system to about 3.5, and hydrolysis was performed by stirring for 3 h. Then, the pH of the silicon sol was adjusted using ammonia water to 9.5, and stirring was performed for 30 min. Then, 50 mg of the pre-magnesium silicon particles prepared in step (1) were added to the sol, and stirring was continued for 30 min. Then, the mixture was transferred to an oil bath pot at 55°C for constant temperature aging for 10 h. After the silicon sol was converted into a gel state, the mixture was taken out after heating at 350°C for 5 h to obtain silicon aerogel-silicon-based nanoparticles with a D50 of 16 μm.

[0127] Comparative Example 2

[0128] (1) The silicon dioxide / silicon monoxide raw material was mixed with magnesium powder at a mass ratio of 500:50, and mechanical mixing was performed using a ball milling method. During the mixing process, the magnesium powder performed metal modification on the silicon particles. Then, high-temperature heat treatment was performed at 950°C for 16 h to obtain pre-magnesium silicon particles with a D50 of 5.7 μm.

[0129] (2) 40 mg PVP was dissolved in 50 mL of deionized water and stirred for 15 min, then 0.4 mL of a 40% polyacrylic acid aqueous solution was added and stirred for 15 min (the mass ratio of PAA to PVP solute was 4:1), then deionized water was added to prepare 100 mL of sol solution and fully stirred for 30 min.

[0130] (3) Take 50 mg of the pre-magnesium silicon particles of step (1), add them into the sol solution, mix thoroughly, immerse for 2 h, low-temperature aging at 55°C to dry, high-temperature pyrolysis at 350°C for 90 min, to obtain carbon aerogel-silicon-based nanoparticles with a D50 of 56 μm.

[0131] Comparative Example 3

[0132] (1) Add an equal amount of acetic acid to a 20% concentration of silica sol, adjust the pH of the system to about 3.5, stir for 3 h, and hydrolyze, then adjust the pH of the silica sol using ammonia water to 9.5, stir for 30 min, then transfer the silica sol to an oil bath pot at 55°C for constant temperature aging for 10 h, after the silica sol is converted into a gel state, heat at 350°C for 5 h, then take out, to obtain silica aerogel with a D50 of 9.5 μm;

[0133] (2) Take the silica / silicon monoxide raw material and magnesium powder, mix them in a mass ratio of 500:50 using a ball milling method for mechanical mixing, the magnesium powder performs metal modification on the silicon particles during the mixing process; then place them in a high-temperature heat treatment at 950°C for 16 h, to obtain pre-magnesium silicon particles with a D50 of 5.7 μm;

[0134] (3) Dissolve 0.4 g of PVP in 50 mL of deionized water and stir for 15 min, then add 0.4 mL of a 40% concentration of polyacrylic acid aqueous solution and stir for 15 min (the mass ratio of PAA to PVP solute is 4:10), then add deionized water to mix and prepare 100 mL of a sol solution and stir thoroughly for 30 min. Using an immersion method, take 50 mg of the silica aerogel prepared in step (1) and the pre-magnesium silicon particles prepared in step (2), add them into the sol solution, mix thoroughly, immerse for 2 h, low-temperature aging at 55°C to dry, high-temperature pyrolysis at 350°C for 90 min, to obtain hierarchical aerogel-silicon-based nanoparticles (i.e. multi-level structure silicon-based negative electrode material) with a D50 of 78 μm;

[0135] (4) Take 20 mg of silicon nanotubes and 5 mg of (NH4)2HPO4, dissolve them in 50 mL of deionized water, stir thoroughly at 45°C for 30 min, dry and grind, and place them in a 500°C environment for heating for 2 h at a heating rate of 5°C / min, to obtain P-doped-silicon nanotubes. Then using a hydrothermal method, take 50 mg of the aerogel-silicon-based nanoparticles prepared in step (3) and 5 mg of the P-doped-silicon nanotubes, hydrothermally treat them at 80°C for 5 h to achieve surface deposition modification, and then anneal them at 850°C for 2 h, to obtain a modified silicon-based negative electrode material. In the modified silicon-based negative electrode material, the particle size D50 of the carbon aerogel is 69 μm, and the particle size D50 of the composite material (modified silicon-based negative electrode material) is 80 μm.

[0136] Effect Implementation Example

[0137] The structural schematic diagram of the silicon-based negative electrode material prepared by the application is shown in Figure 1 .

[0138] The silicon-based negative electrode material prepared above is mixed with the binder PAA and the conductive agent Super P at a mass ratio of 8:1:1, coated on a copper foil after uniform slurry, and vacuum dried and rolled to prepare a negative electrode sheet. A 1 mol / L LiPF6 mixed solvent (volume ratio of ethyl carbonate: dimethyl carbonate: methyl carbonate = 1:2:1) is used as an electrolyte, a polypropylene microporous membrane is used as a separator, and a metal lithium sheet is used as a counter electrode. A button cell is assembled in an argon-filled inert gas glove box system.

[0139] At 25°C, the assembled half-cell is subjected to charge-discharge cycle test using a blue light tester to obtain the data of specific capacity, first coulombic efficiency, and 100-cycle cycle capacity retention rate. The test conditions for specific capacity and first coulombic efficiency are: voltage 0.01V-1.5V, current density 0.05C; and the test conditions for 100-cycle cycle capacity retention rate are: voltage 0.01V-1.5V, current density 0.2C. The test results are shown in Table 1.

[0140] Table 1

[0141]

[0142] As can be seen from the above table, the negative electrode material prepared by the embodiments of the application has excellent first charge specific capacity, first discharge specific capacity, first coulombic efficiency, and cycle performance when applied to a battery.

[0143] The raw material formula for preparing carbon aerogel is adjusted in Examples 1-3, and the above-mentioned electrochemical performance fluctuates within a certain range, but still has a significant advantage compared with the prior art.

[0144] Compared with Example 2, the organic silicon source is selected as the raw material when preparing the silicon aerogel in Example 4, and Example 7 is not modified and deposited, and the negative electrode material prepared by the two methods has improved first charge specific capacity, slightly reduced first discharge specific capacity, first coulombic efficiency, and 100-cycle cycle capacity retention rate when applied to a battery.

[0145] Examples 2, 5 and 6 respectively use different modified deposition materials and methods to optimize the prepared multi-level structure silicon-based negative electrode material. Among them, the effect of Example 2 is the best. It is speculated that this is because in the process of preparing pre-magnesium silicon particles, a part of the metal magnesium still cannot be completely reacted with the silicon oxide source, and the residual metal magnesium has a certain influence on the battery capacity; and the P element doped in Example 2 makes the Mg and Si atoms lose more electrons, forming ionic bonds between Mg-P and Si-P, strengthening the Si-Si ionic bond, and the P-doped silicon nanotube superlattice coexists with ionic bonds and covalent bonds, and the P-doped silicon nanotube can absorb the unreacted Mg element, further improving the lithium ion exchange rate in the cycle process, and effectively avoiding the danger of residual metal magnesium.

[0146] Compared with Example 2, Comparative Example 1 and Comparative Example 2 respectively lack carbon aerogel and silicon aerogel, and the amount of PVP in Comparative Example 3 is too much. When the negative electrode material prepared by it is applied to the battery, the first charge specific capacity, the first discharge specific capacity, the first coulombic efficiency and the capacity retention rate after 100 cycles are all significantly reduced.

Claims

1. A method for preparing a multi-stage structure silicon-based negative electrode material, characterized in that, It comprises the following steps: The silicon aerogel and the pre-magnesium silicon particles are immersed in a carbon aerogel precursor, and are aged and pyrolyzed to obtain; The particle size D50 of the silicon aerogel is 7-11 μm; The pre-magnesium silicon particles have the chemical formula SiMg y O x wherein 1 < y < 2 and 3 < x < 4; the pre-magnesium silicon particles have a particle size D50 of 4 to 7 pm; the pre-magnesium silicon particles are produced by heat treatment of a mixture of a silicon oxide source and metallic magnesium; the silicon oxide source is silicon dioxide and / or silicon monoxide; The raw materials for preparing the carbon aerogel precursor include acrylic acid and polyvinylpyrrolidone, and the mass ratio of the acrylic acid to the polyvinylpyrrolidone is (0.5-15):1; The multi-level structure silicon-based negative electrode material has a double-support structure and a three-dimensional frame structure in the form of an echinoid outside; the particle size D50 of the multi-level structure silicon-based negative electrode material is 50-90 μm; and the particle size D50 of the carbon aerogel in the multi-level structure silicon-based negative electrode material is 50-90 μm.

2. The method for preparing a multi-stage structure silicon-based anode material according to claim 1, characterized in that, The silicon aerogel is prepared by hydrolysis, polycondensation, aging and sintering of a silicon source; the silicon source is an inorganic silicon source and / or an organic silicon source; And / or, the mass ratio of the silicon aerogel to the pre-magnesium silicon particles is 1:(0.5-2); And / or, the mass ratio of the acrylic acid to the polyvinylpyrrolidone is (0.5-10):1; And / or, the mass-volume ratio of the silicon aerogel to the carbon aerogel precursor is 1 mg:(1-2) mL; And / or, the carbon aerogel precursor is prepared by mixing an acrylic acid solution and the polyvinylpyrrolidone; And / or, the time for the immersion is 1-3 h; And / or, the temperature for the aging is 30-80℃; And / or, the temperature for the pyrolysis is 200-600℃; And / or, the time for the pyrolysis is 30-300 min.

3. The method for preparing a multi-stage structure silicon-based anode material according to claim 2, characterized in that, The type of the inorganic silicon source is selected from one or more of silicon tetrachloride, water glass and silica sol; And / or, the type of the organic silicon source is selected from one or more of tetraethyl orthosilicate, methyl orthosilicate and alkoxysilane; And / or, when the organic silicon source is used, a dispersant is further added; And / or, the hydrolysis is performed by adding an acid; And / or, the polycondensation is performed by adding an alkaline substance; And / or, the temperature for the aging is 40-70℃; And / or, the time for the aging is 9-14 h; And / or, when the inorganic silicon source is used, the temperature for the sintering is 300-400℃; And / or, when the inorganic silicon source is used, the time for the sintering is 4-6 h; And / or, when the organic silicon source is used, the temperature for the sintering is 500-800℃; And / or, when the organic silicon source is used, the time for the sintering is 0.5-5 h.

4. The method for preparing a multi-stage structure silicon-based anode material according to claim 3, characterized in that, The concentration of the silica sol is 15-25%.

5. The method for preparing the multi-level silicon-based anode material as described in claim 3, characterized in that, The dispersant is hexadecyl trimethyl ammonium bromide and / or polyethylene glycol.

6. The method for preparing the multi-level silicon-based anode material as described in claim 3, characterized in that, The type of the acid is selected from one or more of hydrochloric acid, oxalic acid, acetic acid, nitric acid and sulfuric acid; And / or, the pH value of the system is adjusted to 3-4 after the acid is added; And / or, stirring is further performed after the acid is added; the time for the stirring is 2-4 h.

7. The method for preparing the multi-level silicon-based anode material as described in claim 3, characterized in that, The alkaline substance is selected from one or more of sodium hydroxide, sodium carbonate and ammonia; And / or, the pH value of the solution is adjusted to 9-10 by adding the alkaline substance; And / or, stirring is further performed after the alkaline substance is added; the time for the stirring is 15-40 min.

8. The method for preparing the multi-level silicon-based anode material as described in claim 1, characterized in that, The mass ratio of the silicon oxide source to the magnesium metal is 500:(30-80). And / or, the temperature of the heat treatment is 500-1200℃; And / or, the time of the heat treatment is 13-18h.

9. The method for preparing the multi-level silicon-based anode material as described in claim 2, characterized in that, The concentration of the acrylic acid solution is 40% or 60%.

10. The method for preparing a multi-stage structure silicon-based anode material according to claim 9, characterized in that, When the concentration of the acrylic acid solution is 40%, the mass-volume ratio of polyvinylpyrrolidone in the polyvinylpyrrolidone solution to the acrylic acid solution is (100-300)mg:1mL; When the concentration of the acrylic acid solution is 60%, the mass-volume ratio of polyvinylpyrrolidone in the polyvinylpyrrolidone solution to the acrylic acid solution is (50-200)mg:1mL.

11. A multi-stage structured silicon-based anode material, characterized in that, It is prepared by the preparation method of any one of claims 1-10; The particle size D50 of the multi-level structure silicon-based negative electrode material is 50-90μm; the particle size D50 of the carbon aerogel in the multi-level structure silicon-based negative electrode material is 50-90μm.

12. A method for producing a modified silicon-based negative electrode material, characterized by, It comprises the following steps: The mixture of the multi-level structure silicon-based negative electrode material and the modifier is heated to prepare a modified silicon-based negative electrode material; the modifier comprises a multi-dimensional material.

13. The method for preparing a modified silicon-based anode material according to claim 12, wherein the silicon-based anode material is a silicon-based anode material represented by the following formula: Si1-xAlx (0 < x < 1). The mass ratio of the multi-level structure silicon-based negative electrode material to the modifier is (1-5):1; And / or, the multi-dimensional material is a zero-dimensional structure material, a one-dimensional structure material, a two-dimensional structure material, or a three-dimensional structure material; And / or, the modifier further comprises a phosphorus-containing compound; And / or, the heating temperature is 70-90℃; And / or, the heating time is 4-6h; And / or, the heating is followed by an annealing operation.

14. The method for preparing a modified silicon-based anode material according to claim 13, characterized in that, The zero-dimensional structure material is a carbon dot; And / or, the one-dimensional structure material is a silicon nanotube and / or a carbon nanotube; And / or, the two-dimensional structure material is one or more of MoS2, MXene, and graphene; And / or, the three-dimensional structure material is a cage-type polysilsesquioxane and / or graphite.

15. The method for preparing a modified silicon-based anode material according to claim 14, wherein the silicon-based anode material is a silicon-based anode material represented by the following formula: Si1-xAlx (0 < x < 1). The diameter of the silicon nanotube is 50-70nm.

16. The method of producing a modified silicon-based anode material according to claim 13, wherein The phosphorus-containing compound is (NH4)2HPO4; And / or, the mass ratio of the phosphorus-containing compound to the multi-dimensional material is 1:(3-5); And / or, when the modifier further comprises a phosphorus-containing compound, the modifier is prepared by the following steps: dissolving the multi-dimensional material and the phosphorus-containing compound in a solvent, heating, drying, and calcining.

17. The method of producing a modified silicon-based anode material according to claim 16, wherein The solvent is deionized water; And / or, in the preparation of the modifier, the heating temperature is 40-50℃; And / or, in the preparation of the modifier, the heating time is 20-60min; And / or, the calcining temperature is 400-600℃; And / or, in the calcining process, the rate of temperature rise to the calcining temperature is 1-10℃ / min.

18. The method of producing a modified silicon-based anode material according to claim 13, wherein The annealing temperature is 700-900℃; And / or, the annealing time is 1-3h.

19. A modified silicon-based anode material, characterized in that, It is prepared by the preparation method of any one of claims 12-18; The particle size of the modified silicon-based negative electrode material is 50-90μm; the particle size of the carbon aerogel is 40-60μm.

20. Use of the multi-level structure silicon-based negative electrode material of claim 11 or the modified silicon-based negative electrode material of claim 19 in a battery.

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