Multi-element synergistically doped nano silicon negative electrode material and preparation method and application thereof

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly provides a multi-element synergistically doped nano-silicon negative electrode material as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, melting silicon and a doping element A at a high temperature, cooling, and crushing into nanoparticles to obtain silicon-based solid solution alloy powder; s2, uniformly dispersing the silicon-based solid solution alloy powder in a high-temperature organic solvent under the assistance of a surfactant to obtain dispersion liquid; and S3, adding a doping element B into the dispersion liquid, heating to realize multi-element atomic-scale doping, filtering, and washing to obtain the multi-element synergistically doped nano-silicon negative electrode material. According to the preparation method, atomic-scale uniform doping (not simple compounding of two phases) of multiple elements to silicon is realized through the eutectic alloy medium, and the silicon-based negative electrode material with excellent comprehensive performance is obtained through specific doping sequence design (the element which is in solid solution with the silicon is introduced firstly, and then the element which forms the eutectic alloy with the element is introduced).

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a multi-element synergistic doped nano-silicon anode material, its preparation method, and its application. Background Technology

[0002] As a core component of modern electrochemical energy storage, the improvement of energy density and cycle life of lithium-ion batteries has always been a focus of attention in industry and academia. Among many anode materials, silicon stands out due to its extremely high theoretical specific capacity (approximately 4200 mAh g⁻¹). -1 With its abundant natural reserves, silicon is considered one of the most promising next-generation anode materials. However, silicon materials undergo significant volume changes (approximately 300%) during charge and discharge, leading to electrode material cracking, repeated growth and destruction of the solid electrolyte interface (SEI), and consequently, rapid capacity decay and battery failure. Furthermore, silicon's intrinsic electronic conductivity and ion diffusion rate are relatively low, limiting its actual rate performance.

[0003] To overcome these problems, researchers have proposed various strategies for modifying silicon materials, mainly including nanostructuring, porous structure design, compositing with carbon materials, and element doping. Among these, metal doping, as an effective method to regulate the electronic structure and mechanical stability of silicon materials, has received widespread attention. For example, introducing metals such as copper, germanium, and aluminum into silicon can form alloy phases with better conductivity or construct high-entropy stable structures, which not only improves the material's electronic conductivity but also helps buffer volume expansion and suppress particle pulverization.

[0004] Nevertheless, existing metal doping technologies still face many challenges: doping uniformity is difficult to control, some methods can only achieve surface modification, and insufficient bulk doping can still lead to structural failure during long-term cycling; although high doping content can improve conductivity, it often sacrifices the effective capacity of silicon materials, which is not conducive to achieving the design goal of high energy density batteries; some metal doping processes rely on complex methods such as high-temperature vapor deposition and magnetron sputtering, which have high equipment costs and harsh reaction conditions, limiting their potential for large-scale production.

[0005] Patent CN117673280A, by doping silicon materials with appropriate amounts of aluminum, magnesium, calcium, molybdenum, niobium, scandium, cerium, and selenium, enables silicon anode materials to simultaneously possess good stress resistance, high ionic conductivity, and high electronic conductivity. However, this patent uses mechanical ball milling followed by high-temperature annealing to achieve metal doping, which easily introduces impurities; moreover, the metals are mostly composited with silicon in the form of large particles, rather than being atomically doped at the microscopic level, resulting in a limited modification effect on the silicon anode. Patent CN118800896B, on the other hand, uses porous carbon as a substrate. In a vacuum evaporation furnace, silicon and metal doping sources are heated to form vapor, which diffuses into the porous carbon material for silicon deposition and metal doping. After carbon coating, the doped silicon-carbon composite anode material is obtained. This invention vaporizes the silicon and metal sources at high temperatures, requiring excessive energy consumption; furthermore, to ensure uniform distribution of silicon and metal, the deposition process must be slow, further increasing costs and making it difficult to scale up production capacity.

[0006] Therefore, developing a metal doping method that can achieve uniform dispersion and efficient doping in silicon substrates, with simple processing, controllable cost, and large-scale mass production capability, is crucial for promoting the commercial application of silicon-based anodes. This method should balance high capacity, long cycle stability, and high coulombic efficiency, providing a feasible material basis for the development of next-generation high-energy-density lithium-ion batteries. Summary of the Invention

[0007] This invention provides a multi-element synergistic doped nano-silicon anode material, its preparation method, and its application, with the aim of solving the aforementioned problems existing in the background art.

[0008] To achieve the above objectives, embodiments of the present invention provide a multi-element synergistic doped nano-silicon anode material, its preparation method, and its application. The present invention achieves atomic-level uniform doping of silicon by multiple elements (rather than a simple two-phase composite) through a eutectic alloy medium, and obtains a silicon-based anode material with excellent comprehensive performance through a specific doping sequence design (first introducing elements that are dissolved in silicon, then introducing elements that form a eutectic alloy with it).

[0009] One aspect of the present invention provides a method for preparing a multi-element synergistically doped nano-silicon anode material, comprising the following steps:

[0010] S1: Take silicon and dopant element A, melt them at high temperature, cool them, and crush them into nanoparticles to obtain silicon-based solid solution alloy powder;

[0011] S2: The silicon-based solid solution alloy powder is uniformly dispersed in a high-temperature organic solvent with the assistance of a surfactant to obtain a dispersion.

[0012] S3: Add dopant element B to the dispersion, heat to achieve multi-element atomic-level doping, filter and wash to obtain the multi-element synergistic doped nano-silicon anode material.

[0013] Preferably, in step S1, the silicon is industrial metallic silicon, in the form of silicon blocks or ingots, with a purity >99.5%; the purity of industrial metallic silicon does not need to be too high, as excessive purity will increase the cost of raw materials; and an appropriate amount of impurities can be regarded as bulk doping of silicon, which is beneficial to improving electrochemical performance.

[0014] Preferably, the dopant element A is at least one of germanium, tin, aluminum, boron, phosphorus, and arsenic; the nanoparticle size is 50~500nm; in some embodiments, the selected nanoparticle size is greater than or equal to 50nm and less than or equal to 500nm, for example, 50nm, 55nm, 60nm, ..., 350nm, 400nm, 450nm or 500nm.

[0015] Preferably, the mass fraction of dopant element A in the silicon-based alloy solid solution is 0.1% to 50%. In some embodiments, the mass fraction of dopant element A in the selected silicon-based alloy solid solution is greater than or equal to 0.1% and less than or equal to 50%, for example, 0.1%, 0.5%, 1.0%, ..., 5%, 10%, 15% ... 35%, 40%, 45% or 50%.

[0016] Preferably, in step S1, the high-temperature melting temperature is 500℃~2500℃, and the melting time is 1~24h; the crushing method is at least one of mechanical ball milling, air jet milling, and sand milling. In some embodiments, the selected melting temperature is higher than or equal to 500℃ and lower than or equal to 2500℃, for example, 500℃, 550℃, 600℃, 650℃...1000℃, 1500℃, 2000℃ or 2500℃.

[0017] Preferably, in step S2, the high-temperature organic solvent is at least one of dimethyl sulfoxide, sulfolane, hexamethylphosphoric triamine, 1,3-dimethyl-2-imidazolinone, triethylene glycol dimethyl ether, dibutyl phthalate, dioctyl phthalate, tributyl phosphate, propylene carbonate, ethylene carbonate, nitrobenzene, cresol, and decahydronaphthalene; the surfactant is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium α-olefin sulfonate, sodium fatty alcohol sulfate, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dioctadecyldimethylammonium chloride, polyether polyol, coconut oil fatty acid diethanolamide, and lauric acid diethanolamide; the solid content of the silicon-based solid solution alloy powder in the dispersion is 10% to 50%; and the mass ratio of the surfactant to the silicon-based solid solution alloy powder is 1:50 to 1:5.

[0018] Preferably, in step S2, the dispersion method is at least one of ultrasonication, sand milling, and homogeneous dispersion.

[0019] Preferably, in step S3, the dopant element B is at least one of lead, indium, silver, copper, bismuth, zinc, antimony, aluminum, gold, and gallium, and the powder particle size is 20~200nm; in some embodiments, the selected dopant element B powder particle size is greater than or equal to 20nm and less than or equal to 200nm, for example, 20nm, 25nm, 30nm, ..., 100nm, 150nm, or 200nm.

[0020] Preferably, the dopant element B can form a multi-element eutectic alloy with element A in the silicon-based solid solution alloy powder; the introduced dopant element B can undergo a eutectic reaction with element A in the existing A-Si solid solution, thereby generating a liquid alloy medium at a lower temperature, promoting the efficient diffusion and uniform doping of B atoms into the silicon matrix.

[0021] Preferably, the mass fraction of the dopant element in the multi-element synergistic doped nano-silicon anode material is 0.1% to 60%. In some embodiments, the mass fraction of the dopant element in the selected multi-element synergistic doped nano-silicon anode material is greater than or equal to 0.1% and less than or equal to 60%, for example, 0.1%, 0.5%, 1.0%, ..., 5%, 10%, 15%...35%, 40%, 45%, 50%, 55% or 60%.

[0022] Preferably, in step S3, the heating temperature is 100~500℃, and the holding time is 1~24h. In some embodiments, the selected heating temperature is higher than or equal to 100℃ and lower than or equal to 500℃, for example, 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, or 500℃.

[0023] An embodiment of the present invention also provides a multi-element synergistically doped nano-silicon anode material prepared by the above-described preparation method.

[0024] Preferably, the first reversible capacity of the multi-element synergistic doped nano-silicon anode material is 800~3600mAh / g, the first efficiency is 80%~95%, and the capacity retention rate after 100 cycles at 1C is 65~98%.

[0025] Another aspect of the present invention provides the application of a multi-element synergistically doped nano-silicon anode material in lithium-ion batteries.

[0026] The above-described solution of the present invention has the following beneficial effects:

[0027] 1. Fundamentally solves the synthesis and oxidation problems, ensuring the essence of doping. This invention uses elemental metal powder as raw material, and the reaction is carried out in a high-temperature solvent. The reaction process does not introduce oxygen and effectively isolates oxygen, avoiding the oxidation and deactivation of silicon materials. Furthermore, it ensures that the metal and silicon exist in a solid solution / alloy form, achieving true bulk doping. This method avoids the problem of silicon particle agglomeration caused by alloy melting in traditional high-temperature solid-state methods, ensuring the structural integrity of the material, thus fundamentally guaranteeing the effectiveness of doping and the basic morphology of the material.

[0028] 2. Multi-element synergistic doping brings multiple performance improvements. (1) Significantly improves conductivity and rate performance: Atomic-level uniform doping greatly improves the intrinsic electronic conductivity of the material. (2) Excellent structural and mechanical stability: The high entropy effect stabilizes the solid solution phase, inhibits the formation of ordered intermetallic compounds, and makes the crystal structure more stable during cycling. (3) Lattice distortion effect: Doped atoms of different sizes cause severe lattice distortion, which can effectively hinder dislocation movement, improve mechanical strength, and better buffer the volume expansion of silicon during lithiation. (4) Excellent long-term cycling stability: Slow diffusion effect: The multi-element atomic environment restricts each other, reduces the overall atomic diffusion rate, and helps to slow down the phase transition and structural coarsening during cycling. (5) Synergistic enhancement effect: Through element design, conductivity, lithium-ion mobility and structural stability can be comprehensively controlled to produce a "1+1>2" performance superposition effect.

[0029] 3. Outstanding manufacturing process and commercialization advantages. Compared with traditional doping techniques such as physical vapor deposition, this invention requires significantly lower temperatures and is more energy-efficient. The process is simple, easy to scale up, suitable for large-scale production, and has broad commercial application prospects. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of the dual-element doped silicon anode material of Embodiment 1 of the present invention and the nano-silicon / metal composite anode in the prior art;

[0032] Figure 2 This is a doping element distribution diagram of the dual-element doped silicon anode material of Embodiment 1 of the present invention;

[0033] Figure 3 This is a doping element distribution diagram of the dual-element doped silicon anode material of Comparative Example 1 of the present invention. Detailed Implementation

[0034] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0035] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0037] This invention addresses existing problems by providing a multi-element synergistic doped nano-silicon anode material, its preparation method, and its applications.

[0038] Example 1

[0039] A method for preparing a multi-element synergistically doped nano-silicon anode material includes the following steps:

[0040] (1) Industrial silicon and germanium metal were melted at 1000℃ and then broken up by airflow to obtain nanoparticles with a particle size of 400nm. The germanium content in the silicon-based solid solution alloy powder was 10%.

[0041] (2) Silicon-based solid solution alloy powder was ultrasonically dispersed in dibutyl phthalate with the assistance of the surfactant sodium dodecyl sulfate. The solid content of the silicon-based solid solution alloy powder in the dispersion was 35%, and the surfactant content was 1%.

[0042] (3) Add 50 nm of indium metal powder to the dispersion and heat at 300 °C for 4 h to achieve multi-element atomic-level co-doping of silicon (the introduction of dopant element B is intended to form a low eutectic composition multi-element alloy phase with the silicon-based solid solution (which already contains element A) under heating conditions). The mass fraction of the dopant element is 15%. After filtration and washing, the multi-element synergistically doped nano-silicon anode material is finally obtained (structural schematic diagram as shown in the figure). Figure 1 As shown on the left), its doped element distribution diagram is as follows: Figure 2 As shown. Because A and B can form a low-melting-point alloy, at a low temperature of 300℃, under the protection of a high-temperature resistant solvent, B can diffuse into the silicon bulk phase by forming an alloy phase with dopant element A in the silicon-based solid solution, ultimately yielding an A / B dual-element solid solution-doped silicon-based anode material. Figure 2 It can be seen that A / B atoms are uniformly distributed within the bulk phase of silicon particles, rather than agglomerated between silicon particles.

[0043] Multi-element synergistic doping of nano-silicon anode with a sheet density of 2 mg cm⁻¹ -2The electrolyte solute is LiPF6, and the solvents are EC, DMC, and DEC in a volume ratio of 0.3:0.3:0.4. The solute concentration is 1 mol / L. -1 Half-cell testing was performed, including charge-discharge tests between 0.01 and 1.5V (at a current density of 50 mA g). -1 The first three charge-discharge tests were conducted at a current density of 200 mAg. -1 (Cyclic testing was conducted), and the electrochemical performance is shown in Table 1.

[0044] Example 2

[0045] A method for preparing a multi-element synergistically doped nano-silicon anode material includes the following steps:

[0046] (1) Industrial silicon and tin metal were melted at 1100℃ and then broken up by airflow to obtain nanoparticles with a particle size of 300nm. The tin content in the silicon-based solid solution alloy powder was 12%.

[0047] (2) The silicon-based solid solution alloy powder was ultrasonically dispersed in triethylene glycol dimethyl ether with the assistance of the surfactant sodium dodecylbenzene sulfonate. The solid content of the silicon-based solid solution alloy powder in the dispersion was 25%, and the surfactant content was 1.4%.

[0048] (3) Add 80 nm indium metal powder to the dispersion, heat at 200 °C for 2 h to achieve multi-element atomic-level co-doping of silicon, with a doping element mass fraction of 18%, and finally obtain multi-element synergistic doped nano silicon anode material by filtration and washing.

[0049] The electrode preparation, battery assembly and testing were the same as in Example 1, and the electrochemical performance is shown in Table 1.

[0050] Example 3

[0051] A method for preparing a multi-element synergistically doped nano-silicon anode material includes the following steps:

[0052] (1) Industrial silicon and aluminum metal are melted at 800℃ and then broken up by airflow to obtain nanoparticles with a particle size of 700nm. The aluminum content in the silicon-based solid solution alloy powder is 5%.

[0053] (2) Silicon-based solid solution alloy powder was ultrasonically dispersed in 1,3-dimethyl-2-imidazolinone with the assistance of the surfactant cetyltrimethylammonium bromide. The solid content of the silicon-based solid solution alloy powder in the dispersion was 45%, and the surfactant content was 2.1%.

[0054] (3) Add 70 nm zinc metal powder to the dispersion, heat at 350 °C for 3 h to achieve multi-element atomic-level co-doping of silicon, with a mass fraction of 8% of the doped elements, and finally obtain multi-element synergistic doped nano silicon anode material by filtration and washing.

[0055] The electrode preparation, battery assembly and testing were the same as in Example 1, and the electrochemical performance is shown in Table 1.

[0056] Example 4

[0057] A method for preparing a multi-element synergistically doped nano-silicon anode material includes the following steps:

[0058] (1) Industrial silicon and aluminum metal are melted at 800℃ and then broken up by airflow to obtain nanoparticles with a particle size of 700nm. The aluminum content in the silicon-based solid solution alloy powder is 5%.

[0059] (2) Silicon-based solid solution alloy powder was ultrasonically dispersed in 1,3-dimethyl-2-imidazolinone with the assistance of the surfactant cetyltrimethylammonium bromide. The solid content of the silicon-based solid solution alloy powder in the dispersion was 45%, and the surfactant content was 0.8%.

[0060] (3) Add a mixture of 70nm zinc powder and 70nm indium powder to the dispersion, heat at 350℃ for 3h to achieve multi-element atomic-level co-doping of silicon, with a mass fraction of 8% of the doped elements, and finally obtain multi-element synergistic doped nano-silicon anode material by filtration and washing.

[0061] The electrode preparation, battery assembly and testing were the same as in Example 1, and the electrochemical performance is shown in Table 1.

[0062] To highlight the beneficial effects of the present invention, the following comparative examples are provided for the embodiments.

[0063] Comparative Example 1

[0064] By changing step (3) in Example 1, using metallic iron as dopant element B, and controlling other experimental conditions to be the same, a half-cell was assembled for testing. The testing mechanism was the same as in Example 1. The electrochemical performance of the silicon-based anode material obtained is shown in Table 1.

[0065] Comparative Example 2

[0066] By changing step (1) in Example 1, using metallic copper as dopant element A, and controlling other experimental conditions to be the same, a half-cell was assembled for testing. The testing mechanism was the same as in Example 1. The electrochemical performance of the silicon-based anode material obtained is shown in Table 1.

[0067] Comparative Example 3

[0068] By changing steps (1) and (3) in Example 1, using metallic copper as dopant element A and metallic iron as dopant element B, and controlling other experimental conditions to be the same, a half-cell was assembled for testing. The testing mechanism was the same as in Example 1. The electrochemical performance of the silicon-based anode material obtained is shown in Table 1.

[0069] Comparative Example 4

[0070] By changing steps (2) and (3) in Example 2, the tin-doped silicon alloy powder and indium metal powder were physically mixed and then subjected to a high-temperature solid-phase reaction at the same temperature. Other experimental conditions were kept the same, and half-cells were assembled for testing. The testing mechanism was the same as in Example 2. The electrochemical performance of the silicon-based anode material was shown in Table 1.

[0071] Comparative Example 5

[0072] In Example 3, steps (2) and (3) were changed. The aluminum-doped silicon alloy powder and zinc powder were physically ball-milled at high energy. Other experimental conditions were kept the same. Half cells were assembled and tested. The testing mechanism was the same as in Example 3. The electrochemical performance of the silicon-based anode material was shown in Table 1.

[0073] Table 1 Performance results of silicon-based anode materials in the examples and comparative examples

[0074] As shown in Table 1, comparing Example 1 and Comparative Example 1, when iron is used as dopant element B, iron and germanium cannot form a eutectic alloy. At low heating temperatures, iron will not dissolve with germanium and will not enter the bulk phase of silicon. Therefore, the final material obtained is a mixture of germanium-doped silicon and iron powder (e.g., ...). Figure 3 Table 1 also shows that the electrochemical performance of the silicon-based anode material prepared using iron is poor, especially in terms of cycling performance. The improvement in cycling performance by single-metal doping is not as good as the synergistic effect of bimetallic doping. In Comparative Example 2, when copper is the dopant element A, although copper and silicon can fuse together during the high-temperature melting stage, they will separate into phases upon cooling and will not form a solid solution. Copper exists as large particles in the silicon matrix, which is a copper-silicon composite rather than doping. Later, although indium, a eutectic metal, was used as the dopant element B, it did not form a solid solution with copper or silicon at low temperatures. Therefore, the final product is a mixture of copper / silicon bulk composite and indium powder. As a result, the electrochemical performance is slightly lower than that of Comparative Example 1 (solid solution doping of silicon with germanium). In Comparative Example 3, when metallic copper is used as dopant A and metallic iron is used as dopant B, the eutectic element indium is replaced by iron compared to Comparative Example 2. At this time, iron and copper in silicon cannot form a solid solution to achieve doping at low temperature. Therefore, the final material is very similar in structure to Comparative Example 2, which is a mixture of copper / silicon bulk composite and iron powder. Therefore, the electrochemical performance is also similar to that of Comparative Example 2.

[0075] Comparing Example 2 and Comparative Example 4, although both have the same initial discharge capacity, Comparative Example 2 shows a significant decrease in reversible capacity and cycle performance. This is because during the direct high-temperature solid-state reaction, the tin-doped silicon alloy powder and the indium powder melt and adhere, increasing the silicon particle size and making the silicon structure more prone to breakage during charging and discharging. Furthermore, the silicon undergoes a certain degree of oxidation during the high-temperature solid-state reaction, leading to a decrease in reversible capacity. In contrast, the high-temperature reaction under organic solvent protection isolates oxygen, and because the particles are uniformly dispersed in the solvent, the reactions between each particle are independent and do not come into contact with each other, preventing an increase in silicon particle size. Therefore, the electrochemical performance of Example 2 is far superior to that of Comparative Example 4.

[0076] Comparing Example 3 and Comparative Example 5, it can be seen that during the physical high-energy ball milling of aluminum-doped silicon alloy powder and zinc powder, a small portion of zinc combines with aluminum, thus co-doping silicon. However, most of the zinc only achieves physical mixing with silicon, which can only be described as a composite of aluminum-doped silicon alloy powder and zinc, rather than doping. Therefore, the effect is naturally not as good as when all zinc is doped into the silicon bulk phase. Furthermore, the physical-mechanical mixing under high-energy ball milling inevitably causes silicon oxidation, leading to a decrease in reversible capacity and first-cycle efficiency. Therefore, compared with the aluminum-zinc bimetallic co-doping in Example 3, the reversible capacity and cycle retention rate of Comparative Example 5 are significantly reduced.

[0077] A comparison of Examples 3 and 4 shows that, although the total content of doped elements is the same, the cycle capacity retention rate of silicon-based anode materials is better when three metals are synergistically doped compared to bimetallic synergistic doping. This is because the structure of silicon-based anode materials is more stable under the synergistic effect of the three metals.

[0078] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a multi-element synergistic doped nano-silicon anode material, characterized in that, Includes the following steps: S1: Take silicon and dopant element A, melt them at high temperature, cool them, and crush them into nanoparticles to obtain silicon-based solid solution alloy powder; S2: The silicon-based solid solution alloy powder is uniformly dispersed in a high-temperature organic solvent with the assistance of a surfactant to obtain a dispersion. S3: Add dopant element B to the dispersion, heat to achieve multi-element atomic-level doping, filter and wash to obtain the multi-element synergistic doped nano-silicon anode material.

2. The method for preparing a multi-element synergistically doped nano-silicon anode material according to claim 1, characterized in that, In step S1, the silicon is industrial metallic silicon, in the form of silicon blocks or ingots, with a purity >99.5%; the dopant element A is at least one of germanium, tin, aluminum, boron, phosphorus, and arsenic; the nanoparticle size is 50~500nm; and the mass fraction of dopant element A in the silicon-based alloy solid solution is 0.1%~50%.

3. The method for preparing a multi-element synergistically doped nano-silicon anode material according to claim 1, characterized in that, In step S1, the high-temperature melting temperature is 500℃~2500℃, and the melting time is 1~24h; the crushing method is at least one of mechanical ball milling, air jet milling, and sand milling.

4. The method for preparing a multi-element synergistically doped nano-silicon anode material according to claim 1, characterized in that, In step S2, the high-temperature organic solvent is at least one of dimethyl sulfoxide, sulfolane, hexamethylphosphoric triamine, 1,3-dimethyl-2-imidazolinone, triethylene glycol dimethyl ether, dibutyl phthalate, dioctyl phthalate, tributyl phosphate, propylene carbonate, ethylene carbonate, nitrobenzene, cresol, and decahydronaphthalene; the surfactant is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium α-olefin sulfonate, sodium fatty alcohol sulfate, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dioctadecyldimethylammonium chloride, polyether polyol, coconut oil fatty acid diethanolamide, and lauric acid diethanolamide; the solid content of the silicon-based solid solution alloy powder in the dispersion is 10% to 50%; the mass ratio of the surfactant to the silicon-based solid solution alloy powder is 1:50 to 1:

5.

5. The method for preparing a multi-element synergistically doped nano-silicon anode material according to claim 1, characterized in that, In step S2, the dispersion method is at least one of ultrasonication, sand milling, and homogeneous dispersion.

6. The method for preparing a multi-element synergistically doped nano-silicon anode material according to claim 1, characterized in that, In step S3, the dopant element B is at least one of lead, indium, silver, copper, bismuth, zinc, antimony, aluminum, gold, and gallium, and the powder particle size is 20~200nm; the dopant element B can form a multi-element eutectic alloy with element A in the silicon-based solid solution alloy powder; the mass fraction of the dopant element in the multi-element synergistic doped nano-silicon anode material is 0.1%~60%.

7. The method for preparing a multi-element synergistically doped nano-silicon anode material according to claim 1, characterized in that, In step S3, the heating temperature is 100~500℃ and the holding time is 1~24h.

8. A multi-element synergistically doped nano-silicon anode material prepared by the preparation method according to any one of claims 1 to 7.

9. The multi-element synergistic doped nano-silicon anode material according to claim 8, characterized in that, The first reversible capacity of the multi-element synergistic doped nano-silicon anode material is 800~3600 mAh / g, the first efficiency is 80%~95%, and the capacity retention rate is 65~98% after 100 cycles at 1C.

10. Application of a multi-element synergistic doped nano-silicon anode material in lithium-ion batteries.

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