Precipitation-strengthened micron silicon negative electrode material, preparation method and application thereof

Abstract

The application belongs to the technical field of lithium ion battery negative electrode materials, and relates to a precipitation strengthened micron silicon negative electrode material and a preparation method and application thereof, the preparation method comprising the following steps: S1: silicon particles and scandium particles are in-situ doped through smelting to obtain a silicon-scandium alloy ingot; S2: after the silicon-scandium alloy ingot is subjected to solid solution treatment, the silicon-scandium alloy ingot is immersed in a cooling liquid at high temperature to obtain a supersaturated solid solution; S3: the supersaturated solid solution is subjected to aging treatment to obtain a desolvated silicon-scandium alloy ingot; and S4: the desolvated silicon-scandium alloy ingot is ground in a sand mill, and after centrifugation, a micron silicon-scandium negative electrode material is obtained. The application effectively solves the problem of insufficient silicon body phase conductivity, and at the same time, fine scandium silicide precipitation phases are pinned in the micron silicon matrix, the mechanical properties of the material are improved, the damage of a huge lithiation stress to the silicon material is effectively resisted, and good fast charging performance is provided under the premise of ensuring structural stability.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery anode material technology, specifically, it relates to a precipitation-strengthened micron-sized silicon anode material, its preparation method and application. Background Technology

[0002] Lithium-ion batteries play a crucial role in new energy vehicles, smart terminals, and renewable energy storage. Silicon (Si) possesses a high theoretical capacity (4200 mAh / g), effectively improving the energy density of lithium-ion batteries. Compared to industrially produced nano-silicon, micron-sized silicon offers advantages such as lower cost, smaller specific surface area, and higher tap density. These advantages translate into higher volumetric energy density, superior coulombic efficiency, and fewer side reactions, making it an increasingly attractive candidate material for practical batteries. However, Si exhibits volume expansion exceeding 300% during lithium insertion / extraction, has a critical fracture size of only 150 nm, and insufficient intrinsic strength, making it unable to withstand the enormous internal stresses during lithium insertion / extraction. This leads to the initiation, further expansion, and aggregation of microcracks into large cracks, causing material pulverization and capacity decay. At the electrode level, it can also cause electrode film cracking and detachment, resulting in battery performance degradation and even safety accidents, especially under fast charging conditions. This severely restricts the application of silicon anodes in lithium-ion batteries.

[0003] Precipitation strengthening is one of the most effective and widely used methods to improve the properties of metallic materials such as aluminum alloys, high-temperature alloys, and high-strength steels. Its core principle is to introduce uniformly fine, dispersed precipitates into the matrix to hinder dislocation movement and enhance the material's strength. Utilizing the temperature-dependent solubility of alloying elements, precise control of the solution treatment, quenching, and aging processes is key to achieving precipitation strengthening. Introducing the concept of precipitation strengthening into micron-sized silicon holds promise for improving its mechanical properties and electrical conductivity. However, this approach has not yet been applied to silicon anodes.

[0004] Therefore, developing a precipitation-reinforced micron-sized silicon anode material with a simple preparation process, low energy consumption, and large-scale production capability to solve the problems of low intrinsic strength and poor conductivity of existing silicon anode materials is of great significance to the development of silicon anode materials for batteries. Summary of the Invention

[0005] The main objective of this invention is to overcome the shortcomings of the prior art and provide a micron-sized silicon anode material, its preparation method and application, which solves the problems of poor bulk conductivity and large volume expansion of silicon anode materials. The preparation process is simple, has a short cycle and low energy consumption, and can be mass-produced.

[0006] To achieve the above objectives, the specific technical solution is as follows:

[0007] This invention provides a method for preparing a precipitation-enhanced micron-sized silicon anode material, comprising the following steps:

[0008] S1: Silicon particles and scandium particles are doped in situ through melting to obtain silicon-scandium alloy ingots;

[0009] S2: After the silicon-scandium alloy ingot is subjected to solid solution treatment, it is immersed in a cooling liquid at high temperature to obtain a supersaturated solid solution;

[0010] S3: The supersaturated solid solution is subjected to aging treatment to obtain a silicon-scandium alloy ingot after solvent removal;

[0011] S4: Grind the desolventized silicon-scandium alloy ingot in a sand mill, and centrifuge it to obtain micron-sized silicon-scandium anode material.

[0012] This invention uses silicon particles and scandium particles as raw materials to prepare a silicon-scandium alloy through vacuum melting. After solution treatment and aging heat treatment, a precipitation-strengthened silicon-scandium alloy is obtained, which can effectively solve the problem of insufficient conductivity of the silicon bulk phase. At the same time, the fine scandium silicide precipitate phase is pinned in the micron-sized silicon matrix, improving the mechanical properties of the material and effectively resisting the damage of the silicon material to the huge lithiation stress. Under the premise of ensuring structural stability, it provides good fast-charging performance and provides a reference for the preparation of high-performance micron-sized silicon anodes.

[0013] Further, in step S1, the mass ratio of silicon particles to scandium particles is 90.0-99.9:0.1-10.0; preferably, the mass ratio is 95.0-99.9:0.1-5; more preferably, the mass ratio is 97.0-99.0:1-3.

[0014] The selection of the mass ratio of silicon particles to scandium particles in this invention is crucial. If the scandium content is too high, exceeding the solid solubility of scandium in silicon, it will be difficult for a precipitate phase to form. Conversely, if the scandium content is too low, there will be less precipitate phase, making it difficult to effectively anchor the micron-sized silicon substrate.

[0015] Furthermore, in step S1, the silicon particles and scandium particles are remelted at least three times to ensure uniform composition.

[0016] Further, in step S2, the solution treatment is carried out in an inert atmosphere tube furnace, heated to 800-1450 °C at a rate of 1-25 °C / min, held at that temperature for 10-120 min, and then removed from the tube furnace and cooled to room temperature in a coolant to obtain a supersaturated solid solution; preferably, the coolant is water or liquid nitrogen, more preferably liquid nitrogen.

[0017] Furthermore, the inert atmosphere is argon;

[0018] The heating rate is preferably 1-10 °C / min; more preferably 3-5 °C / min;

[0019] The preferred heating temperature is 900-1250 °C; more preferably 1100-1200 °C.

[0020] The heat preservation time is preferably 30-100 min; more preferably 40-90 min.

[0021] In this invention, the selection of the heating temperature and cooling rate in step S2 of the heat treatment is a key process parameter. If the heating temperature is insufficient, it is difficult to heat the sample above the solid solubility line, and scandium cannot dissolve into silicon. If the heating temperature is too high, the silicon matrix grains will dissolve, causing overheating. If the cooling rate is too slow, the precipitation of Sc cannot be suppressed, and a supersaturated solid solution cannot be obtained. Therefore, rapid cooling in a coolant is necessary to maintain the supersaturated solid solution at room temperature.

[0022] Further, in step S3, the aging treatment is carried out in an inert atmosphere tube furnace, where the temperature is increased to 300-700 °C at a rate of 1-25 °C / min, held for 1-24 h, and then cooled to room temperature in the furnace to obtain a precipitation-strengthened silicon-scandium alloy ingot.

[0023] Furthermore, the inert atmosphere is preferably argon;

[0024] The heating rate is preferably 1-10 °C / min; more preferably 3-5 °C / min;

[0025] The preferred heating temperature is 400-600 °C; more preferably 450-550 °C.

[0026] The heat preservation time is preferably 3-15 h; more preferably 5-8 h.

[0027] The heating temperature and holding time in step S3 of this invention are key process parameters. If the heating temperature is high and the holding time is long, the precipitate phase will grow larger and will be less effective in pinning.

[0028] Furthermore, in step S4, the rotational speed of the sand mill is 500-2500 r / min, and the sand milling time is 30-120 min.

[0029] Further, in step S4, the centrifugation speed is 100-800 r / min, and the centrifugation time is 3-60 min.

[0030] This invention can obtain silicon-scandium alloy powder with similar particle size by grinding and centrifugation, and can obtain silicon-scandium alloy powder with a particle size distribution of 0.5-1 μm.

[0031] The present invention also provides a micron-sized silicon anode material, which is prepared by the above-described preparation method.

[0032] This invention also provides the application of the above-mentioned micron-sized silicon anode material in the preparation of lithium-ion battery anode materials.

[0033] The present invention further provides a lithium-ion battery, comprising a positive electrode material, a negative electrode material, an electrolyte, and a separator; wherein the negative electrode material comprises the above-mentioned micron-sized silicon negative electrode material.

[0034] Compared with the prior art, the present invention has the following significant advantages:

[0035] This invention prepares ScSi by combining in-situ doping of silicon with solid solution treatment and heat treatment for aging precipitation. 1.67 Precipitation-enhanced micron-sized silicon anode materials provide a reference scheme for the structural design of micron-sized silicon, and the preparation process is short and easy to scale up.

[0036] The micron-sized silicon anode material prepared by this invention has high conductivity (ScSi). 1.67 The nano-precipitated phase is dispersed in the micron-sized silicon matrix, which effectively improves the bulk conductivity of the micron-sized silicon, giving it excellent fast-charging performance as a negative electrode for lithium-ion batteries.

[0037] The micron-sized silicon anode material prepared by this invention, ScSi 1.67 The pinning effect induced by nanoprecipitated phases effectively improves the intrinsic strength of silicon, inhibits the crack propagation caused by volume expansion, and brings excellent structural stability, showing good application prospects. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 This is the XRD pattern of the silicon-scandium alloy ingot prepared in Example 1 of this invention;

[0040] Figure 2 This is an XPS image of the silicon-scandium alloy ingot prepared in Example 1 of this invention;

[0041] Figure 3 This is the Si-Sc binary phase diagram of the present invention;

[0042] Figure 4 The Si / ScSi prepared in Example 1 of this invention 1.67 Laser particle size distribution of the negative electrode;

[0043] Figure 5The Si / ScSi prepared in Example 1 of this invention 1.67 Scanning electron microscope (SEM) image of the negative electrode material;

[0044] Figure 6 The Si / ScSi prepared in Example 1 of this invention 1.67 Transmission electron microscopy (TEM) image of the negative electrode material;

[0045] (a) is an overall morphology diagram of the micron-sized silicon material; (b) is a magnified view of a portion of (a).

[0046] (c) is a high-resolution transmission electron microscopy (HRTEM) image of micron-sized silicon material;

[0047] Figure 7 The Si / ScSi prepared in Example 1 of this invention 1.67 Tap density diagram of the negative electrode;

[0048] Figure 8 The Si / ScSi prepared in Example 1 of this invention 1.67 Charge-discharge curve of the negative electrode;

[0049] Figure 9 The Si / ScSi prepared in Example 1 of this invention 1.67 Cyclic performance of the negative electrode at 2 A / g;

[0050] Figure 10 The Si / ScSi prepared in Example 1 of this invention 1.67 Cyclic performance of the negative electrode at 5 A / g;

[0051] Figure 11 The Si / ScSi prepared in Comparative Example 1 of this invention 1.67 XRD pattern of negative electrode material (Sc content 5~10%);

[0052] Figure 12 The Si / ScSi prepared in Comparative Example 1 of this invention 1.67 Cyclic performance diagram of the negative electrode at 5 A / g (Sc content 5~10%);

[0053] Figure 13 The Si / ScSi prepared in Comparative Example 2 of this invention 1.67 (Sc content ≤ 1%) Cyclic performance diagram of the negative electrode at 5 A / g. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] Unless otherwise specified in the embodiments of the present invention, the techniques or conditions described in the literature in this field or the product instructions shall be followed; if the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through legitimate channels.

[0056] This invention does not impose specific limitations on the preparation methods of battery negative electrode materials and lithium-ion batteries; conventional methods in the field can be used for preparation.

[0057] Example 1

[0058] This embodiment provides a method for preparing a micron-sized silicon anode material, including the following steps:

[0059] (1) Place scandium particles and silicon particles (2% scandium particles added) in a vacuum melting furnace, remelt 3 times, and then cool with the furnace to obtain silicon-scandium alloy ingots;

[0060] (2) The silicon-scandium alloy ingot obtained in step (1) is placed in a tube furnace under an argon atmosphere. The tube furnace is heated to 1150 °C at a heating rate of 5 °C / min and held for 30 min. After the holding period, the alloy ingot is quickly removed from the furnace and placed in liquid nitrogen to be instantly cooled to room temperature to obtain a supersaturated silicon-scandium alloy ingot. Figure 3 As can be seen from the Si-Sc binary phase diagram, this method can maintain the supersaturated state up to room temperature.

[0061] (3) The supersaturated silicon-scandium alloy ingot obtained in step (2) is placed in a tube furnace under an argon atmosphere. The tube furnace is heated to 500 °C at a heating rate of 5 °C / min and held at that temperature for 6 h. After the holding period, the furnace is cooled to allow the supersaturated silicon-scandium alloy ingot to desolvent and precipitate ScSi. 1.67 Precipitated phase;

[0062] (4) After crushing the desolventized silicon-scandium alloy ingot obtained in step (3), it is placed in a sand mill and milled at a speed of 2000 r / min for 1 h to obtain fine powder. Then, the powder obtained by sand milling is placed in a centrifuge and centrifuged at a speed of 400 r / min for 5 min to obtain micron-sized silicon anode material (Si / ScSi). 1.67 ).

[0063] The XRD pattern of the silicon-scandium alloy ingot obtained in step (1) of this embodiment is shown in the figure. Figure 1 As shown, by Figure 1 It is known that the main component of the alloy ingot is silicon. Due to the extremely low scandium content, ScSi was not detected. 1.67 Characteristic peaks; further detection of the Sc element signal via XPS indicates the successful introduction of scandium into silicon, such as... Figure 2 As shown.

[0064] The micron-sized silicon anode material obtained in step (4) of this embodiment is made from... Figure 4 Laser particle size analysis and Figure 5 The SEM images show that after centrifugation, silicon-scandium alloy powder with a median particle size of about 1 μm was obtained. Figure 6 TEM images show that ScSi was prepared. 1.67 Micron-sized silicon particles dispersed in a diffuse manner.

[0065] The present invention produces Si / ScSi 1.67 The tap density of the negative electrode material is 1.1 g / cm³. 3 ,like Figure 7 As shown; Figure 8 The first charge-discharge curve of this micrometer-sized silicon anode shows an initial coulombic efficiency of 90.2%. Figure 9 The cycling performance of this micron-sized silicon anode at a current density of 2 A / g shows that it retains a specific capacity of 1462.2 mAh / g after 150 cycles, exhibiting good cycling stability. Furthermore, after 200 cycles at a current density of 5 A / g, it still retains a specific capacity of 970.3 mAh / g, demonstrating good high-rate cycling stability. Figure 10 As shown.

[0066] Comparative Example 1

[0067] This comparative example provides a method for preparing a micron-sized silicon anode material, including the following steps:

[0068] (1) Compared with Example 1, the amount of scandium added was increased. Silicon particles and scandium particles (10% scandium added) were placed in a vacuum melting furnace, remelted 3 times, and then the silicon-scandium alloy ingot was taken out after cooling in the furnace.

[0069] (2) Place the silicon-scandium alloy ingot obtained in step (1) into a tube furnace under an argon atmosphere. The tube furnace is heated to 1150 °C at a heating rate of 5 °C / min and held for 30 min. After the holding period, the alloy ingot is quickly removed from the furnace and placed in liquid nitrogen to cool to room temperature.

[0070] (3) The silicon scandium alloy ingot obtained in step (2) is placed in a tube furnace under an argon atmosphere. The tube furnace is heated to 500 °C at a heating rate of 5 °C / min and held for 6 h. After the holding period, the furnace is cooled.

[0071] (4) After crushing the silicon scandium alloy ingot obtained in step (3), put it into a sand mill and grind it at a speed of 2000 r / min for 1 h to obtain fine powder. Then put the powder obtained by sand milling into a centrifuge and centrifuge it at a speed of 400 r / min for 5 min. After centrifugation, silicon scandium alloy powder with a median particle size of about 1 μm is obtained, which is a micron silicon anode material.

[0072] The XRD pattern of the silicon-scandium alloy ingot obtained in step (1) of this embodiment is shown in the figure. Figure 11 As shown, by Figure 11 It can be seen that the main components of the alloy ingot are Si and ScSi. 1.67 Two phases. Figure 12 The cycling performance of this micron-sized silicon material at a current density of 5 A / g is shown, and its cycling capacity decays rapidly.

[0073] Depend on Figure 3 As can be seen from the Si-Sc binary phase diagram, the percentage of Sc element added in step (1) exceeds its maximum solubility. Therefore, some reinforcing phase compounds cannot be dissolved during solid solution treatment, resulting in inclusions in the silicon matrix and affecting the performance of micron-sized silicon.

[0074] Comparative Example 2

[0075] This comparative example provides a method for preparing a micron-sized silicon anode material, including the following steps:

[0076] (1) Compared with Example 1, the amount of scandium added was reduced. Silicon particles and trace amounts of scandium particles (0.5% scandium particles added) were placed in a vacuum melting furnace, remelted 3 times, and then cooled with the furnace to remove the silicon-scandium alloy ingot.

[0077] (2) Place the silicon-scandium alloy ingot obtained in step (1) into a tube furnace under an argon atmosphere. The tube furnace is heated to 1150 °C at a heating rate of 5 °C / min and held for 30 min. After the holding period, the alloy ingot is quickly removed from the furnace and placed in liquid nitrogen to cool to room temperature so that the Sc element is completely dissolved into the silicon matrix.

[0078] (3) The silicon scandium alloy ingot obtained in step (2) is placed in a tube furnace under an argon atmosphere. The tube furnace is heated to 500 °C at a heating rate of 5 °C / min and held for 6 h. After the holding period, the furnace is cooled.

[0079] (4) After crushing the silicon scandium alloy ingot obtained in step (3), put it into a sand mill and grind it at a speed of 2000 r / min for 1 h to obtain fine powder. Then put the powder obtained by sand milling into a centrifuge and centrifuge it at a speed of 400 r / min for 5 min. After centrifugation, silicon scandium alloy powder with a median particle size of about 1 μm is obtained, which is a micron silicon anode material.

[0080] Figure 13 The cycling performance of this micron-sized silicon material at a current density of 5 A / g is shown, and its capacity decays rapidly during cycling.

[0081] Depend on Figure 3 As can be seen from the Si-Sc binary phase diagram, if the amount of Sc element added in step (1) is too small, the strengthening effect on the micron-sized silicon substrate is limited, and it is difficult to withstand the huge stress generated during the cycle, resulting in electrode pulverization failure and poor electrochemical performance.

[0082] Comparative Example 3

[0083] This comparative example provides a method for preparing a micron-sized silicon anode material, including the following steps:

[0084] (1) Place scandium particles and silicon particles (2% scandium particles added) in a vacuum melting furnace, remelt 3 times, and then cool with the furnace to remove the silicon-scandium alloy ingot;

[0085] (2) Place the silicon-scandium alloy ingot obtained in step (1) into a tube furnace under an argon atmosphere. The tube furnace is heated to 1400 °C at a heating rate of 5 °C / min and held for 30 min. After the holding period, the alloy ingot is quickly removed from the furnace and placed in liquid nitrogen to cool to room temperature.

[0086] (3) The silicon scandium alloy ingot obtained in step (2) is placed in a tube furnace under an argon atmosphere. The tube furnace is heated to 500 °C at a heating rate of 5 °C / min and held for 6 h. After the holding period, the furnace is cooled.

[0087] (4) After crushing the silicon scandium alloy ingot obtained in step (3), put it into a sand mill and grind it at a speed of 2000 r / min for 1 h to obtain fine powder. Then put the powder obtained by sand milling into a centrifuge and centrifuge it at a speed of 400 r / min for 5 min. After centrifugation, silicon scandium alloy powder with a median particle size of about 1 μm is obtained, which is a micron silicon anode material.

[0088] This comparative model failed to obtain ScSi 1.67 Precipitation-strengthened micron-sized silicon material, due to the heat treatment temperature in step (2) exceeding Figure 3 The eutectic temperature in the grain caused overheating, leading to melting of the grain boundaries.

[0089] Comparative Example 4

[0090] This comparative example provides a method for preparing a micron-sized silicon anode material, including the following steps:

[0091] (1) Place a small amount of scandium particles and silicon particles (2% scandium particles added) in a vacuum melting furnace, remelt 3 times, and then cool with the furnace to remove the silicon-scandium alloy ingot;

[0092] (2) Place the silicon-scandium alloy ingot obtained in step (1) into a tube furnace under an argon atmosphere. The tube furnace is heated to 900 °C at a heating rate of 5 °C / min and held for 30 min. After the holding period, the alloy ingot is quickly removed from the furnace and placed in liquid nitrogen to cool to room temperature.

[0093] (3) The silicon scandium alloy ingot obtained in step (2) is placed in a tube furnace under an argon atmosphere. The tube furnace is heated to 500 °C at a heating rate of 5 °C / min and held for 6 h. After the holding period, the furnace is cooled.

[0094] (4) After crushing the silicon scandium alloy ingot obtained in step (3), put it into a sand mill and grind it at a speed of 2000 r / min for 1 h to obtain fine powder. Then put the powder obtained by sand milling into a centrifuge and centrifuge it at a speed of 400 r / min for 5 min. After centrifugation, silicon scandium alloy powder with a median particle size of about 1 μm is obtained, which is a micron silicon anode material.

[0095] This comparative model failed to obtain ScSi 1.67 The precipitation-strengthened micron-sized silicon material is due to the fact that the heat treatment temperature in step (2) is too low, and it fails to heat to the single-phase region of Sc, so that the Sc element cannot be dissolved into the silicon matrix.

[0096] Comparative Example 5

[0097] This comparative example provides a method for preparing a micron-sized silicon anode material, including the following steps:

[0098] (1) Place a small amount of scandium particles and silicon particles (2% scandium particles added) in a vacuum melting furnace, remelt 3 times, and then cool with the furnace to remove the silicon-scandium alloy ingot;

[0099] (2) Place the silicon-scandium alloy ingot obtained in step (1) into a tube furnace under an argon atmosphere. The tube furnace is heated to 1150 °C at a heating rate of 5 °C / min and held for 30 min. After the holding period, the alloy ingot is quickly removed from the furnace and placed in liquid nitrogen to cool to room temperature.

[0100] (3) The silicon scandium alloy ingot obtained in step (2) is placed in a tube furnace under an argon atmosphere. The tube furnace is heated to 500 °C at a heating rate of 5 °C / min and held for 24 h. After the holding period, the furnace is cooled.

[0101] (4) After crushing the silicon scandium alloy ingot obtained in step (3), put it into a sand mill and grind it at a speed of 2000 r / min for 1 h to obtain fine powder. Then put the powder obtained by sand milling into a centrifuge and centrifuge it at a speed of 400 r / min for 5 min. After centrifugation, silicon scandium alloy powder with a median particle size of about 1 μm is obtained, which is a micron silicon anode material.

[0102] This comparative model failed to obtain ScSi 1.67 Precipitation-strengthened micron-sized silicon material, due to the excessively long aging treatment time in step (3), ScSi 1.67 The precipitated phase grows larger and cannot achieve the effect of precipitation enhancement.

[0103] Comparative Example 6

[0104] This comparative example provides a method for preparing a micron-sized silicon anode material, including the following steps:

[0105] (1) Place a small amount of scandium particles and silicon particles (2% scandium particles added) in a vacuum melting furnace, remelt 3 times, and then cool with the furnace to remove the silicon-scandium alloy ingot;

[0106] (2) Place the silicon-scandium alloy ingot obtained in step (1) into a tube furnace under an argon atmosphere. The tube furnace is heated to 1150 °C at a heating rate of 5 °C / min and held for 30 min. After the holding period, the alloy ingot is quickly removed from the furnace and placed in liquid nitrogen to cool to room temperature.

[0107] (3) Place the silicon-scandium alloy ingot obtained in step (2) into a tube furnace under an argon atmosphere. The tube furnace is heated to 500 °C at a heating rate of 5 °C / min and held for 50 min. After the holding period, the furnace is cooled.

[0108] (4) After crushing the silicon scandium alloy ingot obtained in step (3), put it into a sand mill and grind it at a speed of 2000 r / min for 1 h to obtain fine powder. Then put the powder obtained by sand milling into a centrifuge and centrifuge it at a speed of 400 r / min for 5 min. After centrifugation, silicon scandium alloy powder with a median particle size of about 1 μm is obtained, which is a micron silicon anode material.

[0109] This comparative model failed to obtain ScSi 1.67 Precipitation-strengthened micron-sized silicon material, this is due to the excessively short aging time in step (3), ScSi 1.67 The precipitated phase is small in quantity and size, and cannot achieve the effect of precipitation enhancement.

[0110] Comparative Example 7

[0111] This comparative example provides a method for preparing a micron-sized silicon anode material, including the following steps:

[0112] (1) Place a small amount of scandium particles and silicon particles (2% scandium particles added) in a vacuum melting furnace, remelt 3 times, and then cool with the furnace to remove the silicon-scandium alloy ingot;

[0113] (2) Place the silicon-scandium alloy ingot obtained in step (1) into a tube furnace under an argon atmosphere. The tube furnace is heated to 1150 °C at a heating rate of 5 °C / min and held for 30 min. After the holding period, the alloy ingot is cooled to room temperature with the furnace.

[0114] (3) Place the silicon-scandium alloy ingot obtained in step (2) into a tube furnace under an argon atmosphere. The tube furnace is heated to 500 °C at a heating rate of 5 °C / min and held for 50 min. After the holding period, the furnace is cooled.

[0115] (4) After crushing the silicon scandium alloy ingot obtained in step (3), put it into a sand mill and grind it at a speed of 2000 r / min for 1 h to obtain fine powder. Then put the powder obtained by sand milling into a centrifuge and centrifuge it at a speed of 400 r / min for 5 min. After centrifugation, silicon scandium alloy powder with a median particle size of about 1 μm is obtained, which is a micron silicon anode material.

[0116] This comparative model failed to obtain ScSi 1.67 The precipitation-strengthened micron-sized silicon material was due to the slow cooling rate in step (2), which prevented the formation of a supersaturated solid solution.

[0117] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a precipitation-enhanced micron-sized silicon anode material, characterized in that, Includes the following steps: S1: Silicon particles and scandium particles are doped in situ through melting to obtain silicon-scandium alloy ingots; S2: After the silicon-scandium alloy ingot is subjected to solid solution treatment, it is immersed in a cooling liquid at high temperature to obtain a supersaturated solid solution; S3: The supersaturated solid solution is subjected to aging treatment to obtain a silicon-scandium alloy ingot after solvent removal; S4: Grind the desolventized silicon-scandium alloy ingot in a sand mill, and centrifuge it to obtain micron-sized silicon-scandium anode material.

2. The method for preparing the micron-sized silicon anode material according to claim 1, characterized in that, In step S1, the mass ratio of silicon particles to scandium particles is 90.0-99.9:0.1-10.0; preferably, the mass ratio is 90.0-99.9:0.1-5; more preferably, the mass ratio is 97.0-99.0:1-3.

3. The method for preparing the micron-sized silicon anode material according to claim 1 or 2, characterized in that, In step S1, silicon particles and scandium particles are remelted at least three times.

4. The method for preparing the micron-sized silicon anode material according to claim 3, characterized in that, In step S2, the solution treatment is carried out in an inert atmosphere tube furnace, and the temperature is raised to 800-1450 °C at a rate of 1-25 °C / min. After holding at this temperature for 10-120 min, the solution is removed from the tube furnace and cooled to room temperature in a coolant to obtain a supersaturated solid solution. Preferably, the coolant is water or liquid nitrogen, more preferably liquid nitrogen.

5. The method for preparing the micron-sized silicon anode material according to claim 4, characterized in that, In step S3, the aging treatment is carried out in an inert atmosphere tube furnace, where the temperature is increased to 300-700 °C at a rate of 1-25 °C / min, held for 1-24 h, and then cooled to room temperature in the furnace to obtain a precipitation-strengthened silicon-scandium alloy ingot.

6. The method for preparing the micron-sized silicon anode material according to claim 1 or 2, characterized in that, In step S4, the rotation speed of the sand mill is 500-2500 r / min, and the sand milling time is 30-120 min; And / or, the centrifugation speed is 100-800 r / min, and the centrifugation time is 3-60 min.

7. The method for preparing the micron-sized silicon anode material according to claim 4 or 5, characterized in that, The inert atmosphere is argon.

8. A precipitation-reinforced micron-sized silicon anode material, characterized in that, It is prepared by the method for preparing the micron-sized silicon anode material according to any one of claims 1-7.

9. The application of the micron-sized silicon anode material as described in claim 8 in the preparation of lithium-ion battery anode materials.

10. A lithium-ion battery, comprising a positive electrode material, a negative electrode material, an electrolyte, and a separator, characterized in that, The negative electrode material includes the micron-sized silicon negative electrode material as described in claim 8.

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