Device for preparing lithium battery negative electrode material and method for preparing lithium battery negative electrode material

Abstract

A device and method for preparing a lithium battery negative electrode material. The device comprises: a vacuum chamber, a hollow cathode, an anode, a conveying channel, and an air intake duct. The hollow cathode and the anode are disposed in the vacuum chamber. A reaction area for generating plasma is formed between the hollow cathode and the anode. The conveying channel is disposed in a hollow channel of the hollow cathode. A feeding port of the conveying channel is located at an end of the hollow cathode in the vacuum chamber. The conveying channel is configured to convey particles comprising a first element. An air inlet of the air intake duct is disposed in the reaction area. The air intake duct is configured to introduce a reaction gas comprising a second element. The reaction gas is ionized into a plasma in the reaction area. The plasma and the particles form composite particles which can be used as a lithium battery negative electrode material. The cores of the composite particles comprise the first element. The shells of the composite particles comprise the second element.

Description

Device for preparing negative electrode material of lithium battery and method for preparing negative electrode material of lithium battery Technical Field

[0001] The present invention belongs to the field of composite current collectors for lithium batteries, and in particular relates to a device and method for preparing negative electrode materials for lithium batteries. Background Art

[0002] At present, the main materials used in lithium-ion batteries are carbon-based negative electrode materials and silicon-based negative electrode materials. The carbon used as the negative electrode has a layered microporous structure. The lithium ions that reach the negative electrode are embedded in the layered structure and micropores of the carbon layer. The more lithium ions are embedded, the higher the charging capacity. When the battery is discharged (that is, the process of using the battery), the lithium ions embedded in the negative electrode carbon layer are released and move back to the positive electrode. The more lithium ions that return to the positive electrode, the higher the discharge capacity. Silicon-based materials have greater advantages than carbon materials in some aspects, such as higher specific capacity, better cycle performance, better rate performance, etc., but when they are lithiated, their volume changes by 300%, which is not conducive to the formation of a stable interface film.

[0003] Summary of the Invention

[0004] In view of this, the present application proposes an apparatus and method for preparing negative electrode materials for lithium batteries to prepare negative electrode materials for lithium-ion batteries, thereby increasing the compaction density and conductivity by modifying the particle structure, and improving the problems of lithium-ion batteries in the prior art.

[0005] According to one embodiment of the present application, there is provided an apparatus for preparing negative electrode materials for lithium batteries, the apparatus comprising: a vacuum chamber, a hollow cathode and an anode, a transport channel, and an air inlet pipe. The hollow cathode and the anode are arranged in the vacuum chamber. A reaction zone for generating plasma is formed between the hollow cathode and the anode. The transport channel is arranged in the hollow channel of the hollow cathode. The feed port of the transport channel is located at one end of the hollow cathode in the vacuum chamber. The transport channel is configured to transport particles comprising a first element. The air inlet of the air inlet pipe is arranged in the reaction zone. The air inlet pipe is configured to introduce a reaction gas comprising a second element. The reaction gas is ionized into plasma in the reaction zone. The plasma and the particles form composite particles that can be used as negative electrode materials for lithium batteries. The core of the composite particles comprises the first element. The shell of the composite particles comprises the second element.

[0006] In certain embodiments, the first element is silicon and the second element is carbon.

[0007] In some embodiments, the particles include Si, SiC, SiO2, Si3N4, or a mixture thereof, or mixed particles.

[0008] In certain embodiments, the reactant gas consists of carbon and hydrogen.

[0009] In certain embodiments, the reagent gas includes acetylene.

[0010] In certain embodiments, the first element is carbon and the second element is silicon.

[0011] In certain embodiments, the particles include carbon allotropes.

[0012] In certain embodiments, the reaction gas consists of silicon and hydrogen.

[0013] In certain embodiments, the reactive gas includes silane.

[0014] In some embodiments, the air inlet pipe is disposed on the anode.

[0015] In some embodiments, the delivery channel and the air inlet pipe extend into the vacuum chamber from opposite ends of the vacuum chamber.

[0016] In some embodiments, the air inlet pipe extends from a sidewall of the vacuum chamber into the vacuum chamber.

[0017] In some embodiments, the air inlet pipe includes a plurality of the air inlets.

[0018] In some embodiments, the conveying channel includes a plurality of the feed openings.

[0019] In some embodiments, the air inlet and the feed inlet form an angle of 45 degrees.

[0020] In some embodiments, the hollow cathode is a spiral tube structure, the inner diameter of the spiral tube is ρ, the diameter of the particle is d, and 10 2 d≤ρ≤10 4 d.

[0021] According to one embodiment of the present application, a method for preparing a negative electrode material for a lithium battery is provided. The method comprises: evacuating a chamber to a vacuum and heating it to a process temperature; introducing a reaction gas comprising a second element through an inlet pipe; ionizing the reaction gas into a plasma; delivering particles comprising a first element through a delivery channel disposed within a hollow cathode for a predetermined period of time; and mixing the particles and the plasma to form composite particles that can serve as a negative electrode material for a lithium battery, wherein the core of the composite particle comprises the first element and the shell of the composite particle comprises the second element.

[0022] In some embodiments, evacuating the chamber to a vacuum state and heating the chamber to the process temperature includes: evacuating the pressure of the chamber to 0.01-10 Pa and heating the temperature in the chamber to 300-500° C.

[0023] In some embodiments, introducing the reaction gas including the second element through the gas inlet pipe includes: introducing the reaction gas with a purity of more than 99% at a flow rate of 4000 sccm.

[0024] In some embodiments, ionizing the reaction gas into the plasma includes adjusting the current of the hollow cathode to 300-500A.

[0025] In some embodiments, particles comprising the first element are transported through a transport channel disposed in the hollow cathode within a preset time: the particles are introduced at a rate of 600 g / h 30 seconds after the plasma is formed.

[0026] The equipment proposed in this application is simple, the process is fast, which is conducive to industrial production, and the process is clean without the introduction of impurities. The composite particles thus generated can be used as negative electrode materials for lithium-ion batteries to improve the stability of battery operation. At the same time, they have the advantages of using carbon materials and silicon materials as negative electrode materials, and have both spatial capacity and higher rate performance and specific capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the present application but do not constitute a limitation of the present application. In the accompanying drawings:

[0028] FIG1 is a schematic diagram illustrating a device according to an embodiment of the present application.

[0029] FIG. 2A is a schematic structural diagram of a composite particle according to an embodiment of the present application.

[0030] FIG. 2B illustrates a schematic structural diagram of a composite particle according to an embodiment of the present application.

[0031] FIG3A is a schematic diagram illustrating a device according to an embodiment of the present application.

[0032] FIG. 3B is a schematic diagram illustrating a device according to an embodiment of the present application.

[0033] FIG3C is a schematic diagram illustrating a device according to an embodiment of the present application.

[0034] FIG. 4A is a schematic diagram illustrating a device according to an embodiment of the present application.

[0035] FIG. 4B is a schematic diagram illustrating a device according to an embodiment of the present application.

[0036] FIG. 4C is a schematic diagram illustrating a device according to an embodiment of the present application.

[0037] FIG4D is a schematic diagram illustrating a device according to an embodiment of the present application.

[0038] FIG. 5A is a schematic diagram illustrating a device according to an embodiment of the present application.

[0039] FIG. 5B is a schematic diagram illustrating a device according to an embodiment of the present application.

[0040] FIG6 illustrates a flowchart of a method according to an embodiment of the present application. DETAILED DESCRIPTION

[0041] The following disclosure provides a variety of implementations or illustrations that can be used to implement different features of the present disclosure. The specific examples of components and configurations described below are intended to simplify the present disclosure. As will be appreciated, these descriptions are illustrative only and are not intended to limit the present disclosure. For example, in the description below, forming a first feature on or above a second feature may include certain embodiments in which the first and second features are in direct contact with each other; and may also include certain embodiments in which additional components are formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may reuse component symbols and / or labels in multiple embodiments. Such repetition is for the purposes of brevity and clarity and does not, in itself, represent a relationship between the different embodiments and / or configurations discussed.

[0042] Furthermore, spatially relative terms such as "below," "beneath," "below," "above," and the like may be used herein to facilitate description of the relationship of one component or feature depicted in a figure relative to one or more other components or features. These spatially relative terms are intended to encompass various orientations of the device during use or operation, in addition to the orientation depicted in the figures. The device may be placed in other orientations (e.g., rotated 90 degrees or in other orientations), and these spatially relative descriptive terms should be interpreted accordingly.

[0043] Although the numerical ranges and parameters used to define the broader scope of this application are approximate, the numerical values ​​of the specific examples have been presented herein as precisely as possible. However, any numerical value inherently and inevitably contains standard deviations resulting from individual testing methods. As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specified value or range. Alternatively, the term "about" means that the actual value falls within an acceptable standard error of the mean, as determined by one of ordinary skill in the art. It should be understood that, except in the experimental examples, or unless otherwise expressly indicated, all ranges, amounts, values, and percentages used herein (e.g., to describe material amounts, time periods, temperatures, operating conditions, quantitative ratios, and the like) are modified by the word "about." Therefore, unless otherwise indicated, the numerical parameters disclosed in this specification and the appended claims are approximate and may be modified as needed. At a minimum, these numerical parameters should be understood to include the number of significant digits indicated and to apply normal rounding. Herein, numerical ranges are expressed from one endpoint to another endpoint or between two endpoints; unless otherwise stated, the numerical ranges described herein include the endpoints.

[0044] FIG1 is a schematic diagram of an apparatus 1A according to an embodiment of the present application, wherein the apparatus 1A is used to prepare a negative electrode material for a lithium battery. In certain embodiments, the apparatus 1A includes a vacuum chamber 11 , a hollow cathode 12 , an anode 13 , a transport channel 14 , and an air inlet pipe 15 .

[0045] The hollow cathode 12 and the anode 13 are arranged in the vacuum chamber 11. A reaction zone A1 for generating plasma is formed between the hollow cathode 12 and the anode 13. The transport channel 14 is arranged in the hollow channel of the hollow cathode 12. The feed port 14H of the transport channel 14 is located at one end of the hollow cathode 12 in the vacuum chamber 11. The transport channel 14 is configured to transport particles K1 including a first element. The air inlet pipe 15 is arranged above the anode 13. The transport channel 14 and the air inlet pipe 15 extend into the vacuum chamber 11 from opposite ends of the vacuum chamber 11, respectively. The air inlet 15H of the air inlet pipe 15 is arranged in the reaction zone A1. The air inlet pipe 15 is configured to pass a reaction gas K2 including a second element.

[0046] The preparation process is as follows: First, the vacuum chamber 11 is evacuated to a pressure of 0.01-10 Pa and heated to 400°C. Next, a reactant gas K2 containing the second element and with a purity of 99% or higher is introduced into the vacuum chamber 11 through the inlet pipe 15 at a flow rate of 4000 sccm. Next, the current of the hollow cathode 12 is adjusted to 300-500 A to form a plasma reaction zone A1 between the hollow cathode 12 and the anode 13. After a predetermined time (e.g., but not limited to 30 seconds), particles K1 containing the first element are introduced through the delivery channel 14 at a rate of 600 g / h. At this high temperature, the reactant gas K2 ionizes and mixes with the particles K1 to form composite particles K3, wherein the core of the composite particles K3 contains the first element and the shell contains the second element. Finally, after cooling, the composite particles K3 are discharged from the vacuum chamber 11.

[0047] In one embodiment of the present application, the first element includes silicon and the second element includes carbon. Referring to FIG2A , FIG2A illustrates a schematic structural diagram of a composite particle K3 according to one embodiment of the present application. In some embodiments, the particle K1 can be one of Si, SiC, SiO2, Si3N4, or a mixture thereof, or a mixed particle. The particle size of the particle K1 is 2 μm, and the specific surface area BET is 2 m 2 / g. In some embodiments, the reaction gas K2 is composed of carbon and hydrogen, preferably acetylene. At high temperatures, the carbon-containing reaction gas K2 ionizes, and the carbon therein mixes with the silicon in the particles K1 to form nanocomposite particles K3 having a core of ultrafine silicon particles and an outer shell of a carbon conductor with a regular spatial structure.

[0048] In one embodiment of the present application, the first element includes carbon and the second element includes silicon. Referring to FIG2B , FIG2B illustrates a schematic structural diagram of a composite particle K3 according to another embodiment of the present application. In some embodiments, the particle K1 may be a carbon allotrope, with a particle size of 5 μm and a specific surface area of ​​1 m 2 / g. In certain embodiments, the reactant gas K2 is composed of silicon and hydrogen, preferably silane. At high temperatures, the silicon-containing reactant gas K2 ionizes, whereupon the silicon mixes with the carbon in the particles K1 to form nanocomposite particles K3 comprising an ultrafine, regularly structured carbon conductor core and an outer shell of ultrafine silicon particles. Nanocomposite particles K3, composed of silicon and carbon materials, are used as negative electrode materials for lithium-ion batteries, combining spatial capacity with higher rate capability and specific capacity.

[0049] It should be noted that the placement of components in the apparatus 1A shown in FIG1 is not a limitation of this application. To improve reaction efficiency and material utilization, and to obtain more uniform nanocomposite particles K3, the position and angle of the air inlet pipe 15 can be modified. FIG3A illustrates a schematic diagram of an apparatus 1B according to an embodiment of this application. The apparatus 1B in the embodiment of FIG3A is substantially identical to the apparatus 1A in the embodiment of FIG1 , differing only in the placement of the air inlet pipe 15. Specifically, in the embodiment of FIG3A , the air inlet pipe 15 extends from a sidewall of the vacuum chamber 11 into the vacuum chamber 11, with the air inlet pipe 15 and the delivery channel 14 forming a 90-degree angle. FIG3B illustrates a schematic diagram of an apparatus 1C according to an embodiment of this application. The apparatus 1C in the embodiment of FIG3B is substantially identical to the apparatus 1A in the embodiment of FIG1 , differing only in the placement of the air inlet pipe 15. Specifically, in the embodiment of FIG3B , the air inlet pipe 15 and the delivery channel 14 extend from the same side of the vacuum chamber 11 into the vacuum chamber 11, and the air inlet pipe 15 and the delivery channel 14 are arranged parallel to each other. Figure 3C illustrates a schematic diagram of an apparatus 1D according to an embodiment of the present application. The apparatus 1D in the embodiment of Figure 3C is substantially identical to the apparatus 1A in the embodiment of Figure 1 , differing only in the location of the air inlet pipe 15. Specifically, in the embodiment of Figure 3C , the air inlet pipe 15 extends from the oblique upper end of the vacuum chamber 11 into the vacuum chamber 11, with the air inlet pipe 15 and the delivery channel 14 forming a 45-degree angle.

[0050] It can be easily concluded from the embodiments of Figures 3A, 3B and 3C that the air inlet pipe 15 of the present application can extend into the vacuum chamber 11 from any position of the vacuum chamber 11 and can be set at any angle with the delivery channel 14.

[0051] In addition, the number of air intake pipes 15 can also be changed to obtain more uniform nanocomposite particles K3. Referring to Figures 4A to 4D, they respectively demonstrate schematic diagrams of devices 1A', 1B', 1C' and 1D' according to an embodiment of the present application. In devices 1A', 1B', 1C' and 1D', the difference from devices 1A, 1B, 1C and 1D is that the number of air intake pipes 15 is two. Those skilled in the art should be able to understand the implementation details of Figures 4A, 4B, 4C and 4D, which will not be repeated here. It is understandable that in the present application, the number of air intake pipes 15 can also be three, four or any number.

[0052] Similarly, to improve reaction sufficiency and material utilization, extend the reaction time, and obtain more uniform nanocomposite particles K3, the position, angle, and number of hollow cathodes 12 can be modified. For example, as shown in FIG5A , apparatus 1E includes two hollow cathodes 12. Furthermore, any variation of the hollow cathodes 12, delivery channels 14, and anodes 13 can be combined with various variations of the intake pipe 15 in the above-described embodiments to obtain an apparatus for preparing lithium battery negative electrode materials. This application is not limited to the variations illustrated in the present application.

[0053] In addition, the present application also does not limit the structural shape of the hollow cathode 12. FIG5B shows a schematic diagram of an apparatus 1F according to an embodiment of the present application. The apparatus 1F in the embodiment of FIG5B is substantially the same as the apparatus 1A in the embodiment of FIG1 , with the only difference being that the hollow cathode 12 is in the shape of a spiral tube, and the shape of the delivery channel 14 is also in the shape of a spiral tube. In some embodiments, the inner diameter ρ of the spiral tube and the diameter d of the particle K1 can satisfy 10 2 d≤ρ≤10 4 d. In some embodiments, the inner diameter p of the spiral tube is 50 mm. In some embodiments, corresponding to the spiral structure of the hollow cathode 12, the anode 13 can be a ring-shaped electrode, which surrounds the hollow cathode 12 and is located at one end within the vacuum chamber 11, namely, the inlet 14H of the conveying channel 14. Accordingly, the location of the air inlet pipe 15 can also be changed.

[0054] In addition to the hollow cathode 12 , the present application also does not limit the shapes of the intake pipe 15 and the anode 13 .

[0055] The applicant conducted a series of experiments to verify the compacted density, tap density, and powder conductivity of the resulting composite particles K3. The compacted density test was based on GB / T 24533-2019 Graphite-Based Anode Materials for Lithium-Ion Batteries. The compacted density refers to the density of the entire component after coating and calendering the electrode sheet. For the same material, a higher compacted density indicates a higher volumetric energy density. The tapped density test was based on GB / T 21354-2008 General Method for Determination of Tap Density of Powder Products. The tapped density is a characteristic of the particles themselves before coating them on the anode membrane. The conductivity of the prepared anode material powder was measured using a powder conductivity tester. Higher powder conductivity indicates better battery cyclability. The experimental results are listed in Table 1 below.

[0056] Table 1

[0057] Where D50 and D90 represent the particle sizes corresponding to when the cumulative particle size distribution percentage of the sample reaches 50% and 90%;

[0058] Example 1 is a test conducted on composite particles K3 produced by the apparatus 1A of the embodiment of FIG1 . The core of the composite particles K3 is ultrafine silicon particles, and the shell is a carbon conductor with a regular spatial structure.

[0059] Example 2 is a test conducted on composite particles K3 produced by the apparatus 1A of the embodiment of FIG1 . The core of the composite particles K3 is composed of ultrafine carbon conductive particles with a regular spatial structure, and the shell is composed of ultrafine silicon particles.

[0060] In Example 3, composite particles K3 were generated using an apparatus 1D′ similar to that shown in FIG. 4D . The apparatus included four air inlet pipes 15 , each disposed at an oblique upper end of the vacuum chamber 11 .

[0061] Example 4 is a test of composite particles K3 produced by combining the apparatus of the embodiment of FIG. 4A and the embodiment of FIG. 5B , wherein the apparatus includes two air inlet pipes 15 and two hollow cathodes 12 disposed on the anode 13 ;

[0062] Example 5 is a test conducted using the composite particles K3 produced by the apparatus 1F of the embodiment shown in FIG5B .

[0063] The experimental results show that improving the reaction uniformity and reaction time of particles and plasma by changing the settings of components in the equipment can improve the various properties of the composite particle K3.

[0064] The present application also proposes a method for preparing a negative electrode material for a lithium battery. Referring to Figure 6, Figure 6 illustrates the process steps of a method 60 for preparing a negative electrode material for a lithium battery according to an embodiment of the present application. If similar results can be obtained, the present application is not limited to proceeding in full accordance with the process steps shown in Figure 6. Method 60 may include step 61, step 62, step 63, step 64, and step 65. In step 61, the chamber may be evacuated to a vacuum and heated to a process temperature. In step 61, the chamber may be evacuated to 0.01-10Pa, and heated to 400°C. In step 61, the chamber may be evacuated to 5x10 -2Pa, and heated to 180°C and kept warm for 30-90 minutes. In step 62, a reaction gas including a second element can be introduced through an air inlet pipe. In step 62, a reaction gas (e.g., acetylene or silane) with a purity of 99% or more and including a second element (e.g., carbon or silicon) can be introduced into the chamber at a flow rate of 1000-4000 sccm, and the vacuum degree in the chamber is maintained at 0.1-10 Pa. In step 63, the reaction gas can be ionized into a plasma. In step 63, the arc current of the hollow cathode can be set to 300-500A to form a reaction zone of a plasma zone between the hollow cathode and the anode. In step 64, particles including the first element can be transported through a transport channel provided in the hollow cathode within a preset time. In step 64, particles including the first element (e.g., silicon or carbon) can be introduced at a rate of 300-900 g / h 30 seconds after the plasma is formed. In step 64, particles comprising a first element (e.g., silicon or carbon) may be introduced at a rate of 600 g / h 30 seconds after the plasma is formed. In step 65, the particles and the plasma may be mixed to form composite particles that can serve as a negative electrode material for a lithium battery. In step 65, the ionized reactant gas may be mixed with the particles to form composite particles, wherein the core of the composite particles comprises the first element and the shell comprises the second element.

[0065] After reading the embodiment of FIG1 , those skilled in the art should be able to easily understand the method flow shown in FIG6 . Therefore, detailed description is omitted here to save space.

[0066] The equipment proposed in this application is simple, the process is fast, which is conducive to industrial production, and the process is clean without the introduction of impurities. The composite particles K3 thus generated can be used as the negative electrode material of lithium-ion batteries to improve the stability of battery operation. At the same time, it has the advantages of using carbon materials and silicon materials as negative electrode materials, and has both spatial capacity and higher rate performance and specific capacity.

[0067] As used herein, the terms "approximately," "substantially," "substantially," and "about" are used to describe and take into account small variations. When used in conjunction with an event or circumstance, the terms may refer to instances where the event or circumstance occurred exactly as well as instances where the event or circumstance occurred very approximately. As used herein with respect to a given value or range, the term "approximately" generally means within ±10%, ±5%, ±1%, or ±0.5% of the given value or range. Ranges may be expressed herein as from one endpoint to another or between two endpoints. Unless otherwise specified, all ranges disclosed herein include endpoints. The term "substantially coplanar" may refer to two surfaces that are positioned along the same plane within a few micrometers (μm), for example, within 10 μm, within 5 μm, within 1 μm, or within 0.5 μm positioned along the same plane. When referring to a value or characteristic that is "substantially" the same, the term may refer to a value that is within ±10%, ±5%, ±1%, or ±0.5% of the average of the stated values.

[0068] As used herein, the terms "approximately," "substantially," "essentially," and "about" are used to describe and explain small variations. When used in conjunction with an event or circumstance, the terms may refer to instances where the event or circumstance occurred exactly as well as instances where the event or circumstance occurred very approximately. For example, when used in conjunction with a numerical value, the terms may refer to a range of variation of less than or equal to ±10% of the numerical value, e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, two values ​​may be considered "substantially" or "approximately" the same if the difference between them is less than or equal to ±10% of the mean of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%). For example, "substantially" parallel can refer to an angular variation of less than or equal to ±10° relative to 0°, e.g., less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°. For example, "substantially" perpendicular can refer to an angular variation range of less than or equal to ±10° relative to 90°, for example, less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°.

[0069] For example, two surfaces may be considered coplanar or substantially coplanar if the displacement between the two surfaces is equal to or less than 5 μm, equal to or less than 2 μm, equal to or less than 1 μm, or equal to or less than 0.5 μm. A surface may be considered planar or substantially planar if the displacement between any two points on the surface relative to the plane is equal to or less than 5 μm, equal to or less than 2 μm, equal to or less than 1 μm, or equal to or less than 0.5 μm.

[0070] As used herein, the singular terms "a," "an," and "the" may include plural referents unless the context clearly dictates otherwise. In the description of some embodiments, a component provided "on" or "over" another component may encompass both the case where the former component is directly on (e.g., physically in contact with) the latter component and the case where one or more intermediate components are located between the former and the latter component.

[0071] As used herein, spatially relative terms such as "below," "beneath," "lower," "above," "upper," "lower," "left," "right," etc., may be used herein for ease of description to describe the relationship of one component or feature to another component or feature as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein should be interpreted accordingly. It should be understood that when a component is referred to as being "connected to" or "coupled to" another component, it can be directly connected or coupled to the other component or intervening components may be present.

[0072] The foregoing summarizes several embodiments and detailed features of the present disclosure. The embodiments described in this disclosure can be readily used as a basis for designing or modifying other processes and structures for performing the same or similar purposes and / or obtaining the same or similar advantages of the embodiments introduced herein. These equivalent constructions do not depart from the spirit and scope of the present disclosure and various changes, substitutions, and modifications may be made without departing from the spirit and scope of the present disclosure.

Claims

1. An apparatus for preparing a negative electrode material of a lithium battery, characterized in that, include: Vacuum chamber; A hollow cathode and an anode are disposed in the vacuum chamber, wherein a reaction zone for generating plasma is formed between the hollow cathode and the anode; A conveying channel is disposed in the hollow channel of the hollow cathode, wherein an inlet of the conveying channel is located at one end of the hollow cathode in the vacuum chamber, and the conveying channel is configured to convey particles including a first element; an air inlet pipe, wherein an air inlet of the air inlet pipe is disposed in the reaction zone, and the air inlet pipe is configured to allow a reaction gas including a second element to pass therein; The reaction gas is ionized into plasma in the reaction zone, and the plasma and the particles form composite particles that can be used as negative electrode materials for lithium batteries. The core of the composite particles includes the first element, and the shell of the composite particles includes the second element.

2. The device according to claim 1, characterized in that, The first element is silicon, and the second element is carbon.

3. The device according to claim 2, characterized in that, The particles include single substances or mixtures of Si, SiC, SiO2, Si3N4, or mixed particles.

4. The device according to claim 3, characterized in that, The reaction gas consists of carbon and hydrogen.

5. The device according to claim 4, characterized in that, The reaction gas includes acetylene.

6. The device according to claim 1, characterized in that, The first element is carbon, and the second element is silicon.

7. The device according to claim 6, characterized in that, The particles include carbon allotropes.

8. The device according to claim 7, characterized in that, The reaction gas consists of silicon and hydrogen.

9. The device according to claim 8, characterized in that, The reactive gas includes silane.

10. The device according to claim 1, characterized in that, The air intake pipe is arranged on the anode.

11. The device according to claim 1, characterized in that, The delivery channel and the air inlet pipe extend from opposite ends of the vacuum chamber into the vacuum chamber.

12. The device according to claim 1, characterized in that, The air inlet pipe extends from the side wall of the vacuum chamber into the vacuum chamber.

13. The device according to claim 1, characterized in that The air intake pipe includes a plurality of air intake ports.

14. The device according to claim 1, characterized in that, The conveying channel includes a plurality of feeding ports.

15. The device according to claim 1, characterized in that, The air inlet and the feed inlet form an angle of 45 degrees.

16. The device according to claim 1, characterized in that, The hollow cathode is of a spiral tube structure. The inner diameter of the spiral tube is ρ, and the diameter of the particles is d, satisfying 10 2 d ≤ ρ ≤ 10 4 d.

17. A method for preparing a negative electrode material for a lithium battery, characterized in that, include: The chamber is evacuated to vacuum and heated to process temperature; introducing a reaction gas including a second element through an air inlet pipe; ionizing the reaction gas into plasma; delivering particles comprising a first element through a delivery channel disposed within the hollow cathode within a predetermined time; The particles and the plasma are mixed to form composite particles that can be used as negative electrode materials for lithium batteries, wherein the core of the composite particles includes the first element and the shell of the composite particles includes the second element.

18. The method according to claim 17, wherein Evacuating the chamber to a vacuum and heating the chamber to the process temperature comprises: The pressure of the chamber is evacuated to 0.01-10 Pa, and the temperature in the chamber is heated to 300-500°C.

19. The method according to claim 17, wherein The step of introducing the reaction gas including the second element through the gas inlet pipe comprises: The reaction gas with a purity of 99% or more is introduced at a flow rate of 4000 sccm.

20. The method according to claim 17, wherein Ionizing the reaction gas into the plasma comprises: The current of the hollow cathode was adjusted to 300-500A.

21. The method according to claim 20, characterized in that, delivering particles comprising a first element through a delivery channel disposed in the hollow cathode within a predetermined time: 30 seconds after the plasma was formed, the particles were introduced at a rate of 600 g / h.

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