Fluidized large-scale preparation method for silicon-carbon negative electrode material

Abstract

A fluidized large-scale preparation method for a silicon-carbon negative electrode material, relating to the technical field of battery materials, said method comprising: raw material crushing, a fluidized silicon deposition reaction, and a fluidized carbon deposition reaction. The fluidized silicon deposition reaction and fluidized carbon deposition reaction are carried out in a stirred fluidized bed reactor. The conditions of the stirred fluidized bed reactor comprise: a temperature of 300-1000°C and a stirring speed of 1-240 r / min. By using the stirred fluidized bed reactor to perform composite treatment of a silicon material and a carbon material, large-scale preparation of the silicon-carbon negative electrode material can be achieved. Moreover, the electrical conductivity regulation of the material can be achieved, electrode reaction activity and area can be improved, the diffusion distance of lithium ions can be shortened, the diffusion rate of lithium ions can be increased, and ultimately the battery cycle capacity and rate performance can be improved.

Description

A fluidized large-scale preparation method for silicon-carbon negative electrode materials

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese patent application number 202410399435.1, filed with the Patent Office of China on April 3, 2024, entitled “A fluidized large-scale preparation method for silicon-carbon negative electrode materials,” the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] The present invention relates to the technical field of battery materials, and in particular to a fluidized large-scale preparation method of silicon-carbon negative electrode materials. Background Art

[0004] Against the backdrop of the dual carbon goals, my country's new energy industry has experienced rapid growth in recent years. Research into power battery technologies, particularly lithium-ion batteries, is a crucial area of ​​focus for this industry. The rapidly expanding battery market is constantly pushing for new heights in energy and power density. As anode materials, silicon-based systems, with their high theoretical specific capacity, are considered to hold the greatest potential for development and are well-suited to future market developments.

[0005] The anode materials currently used in commercial lithium-ion batteries primarily include: graphite-based carbon materials, primarily artificial and natural graphite; disordered carbon materials, including hard and soft carbons; lithium titanate materials; and silicon-based materials, primarily including carbon-coated silicon oxide composites and nano-silicon-carbon composites. Because silicon anodes have a moderate lithium insertion potential and eliminate the risk of lithium deposition during charging and insertion, they improve the safety of lithium-ion batteries. Therefore, they are the most promising anode materials to replace graphite as the next generation of high-performance lithium-ion battery anode materials. However, the inherent disadvantages of silicon upon lithiation include large volume expansion (>300%), poor conductivity, and a low lithium-ion diffusion coefficient, hindering their widespread market adoption.

[0006] The silicon in silicon-based materials such as silicon carbon expands greatly during lithiation. The resulting stress will cause the electrode material to pulverize or even fall off from the current collector, and the active material will continuously consume the electrolyte, making it impossible to form a stable solid electrolyte membrane (SEI membrane), resulting in material performance degradation. Moreover, the poor electrical conductivity of silicon will also lead to severe electrode polarization, hindering the diffusion rate of lithium ions and limiting the output power of the battery.

[0007] In view of this, the present invention is proposed.

[0008] Application Contents

[0009] The purpose of the present disclosure is to address the deficiencies in the above-mentioned prior art and provide a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The preparation method provided in the embodiment of the present invention utilizes a stirred fluidized bed reactor to composite silicon materials with carbon materials, thereby achieving continuous large-scale preparation of silicon-carbon negative electrode materials, and can achieve material conductivity regulation, improve electrode reaction activity and area, shorten lithium ion diffusion distance, increase lithium ion diffusion rate, and ultimately improve battery cycle capacity and rate performance. To achieve the above-mentioned purpose, the technical solutions adopted in the embodiment of the present disclosure are as follows:

[0010] The present invention provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials, comprising: raw material crushing, fluidized silicon deposition reaction, and fluidized carbon deposition reaction; wherein the fluidized silicon deposition reaction and fluidized carbon deposition reaction are carried out in a stirred fluidized bed reactor, and the conditions of the stirred fluidized bed reactor include: a temperature of 300-1000°C and a stirring speed of 1-240 r / min. In an optional embodiment, the method includes the following steps:

[0011] Step 1, raw material crushing: the porous carbon material is crushed, ground and sieved to obtain small-particle porous carbon reaction raw materials; Step 2, fluidized silicon deposition reaction: the small-particle porous carbon reaction raw materials obtained in step 1 are placed in a stirred fluidized bed reactor into which a mixture of carrier gas and silicon source gas is introduced to carry out silicon deposition to obtain a silicon-based intermediate;

[0012] Step 3, fluidized carbon deposition reaction: a mixed gas of carrier gas and carbon source is introduced into the silicon-based intermediate product obtained in step 2 to perform carbon deposition to obtain a silicon-carbon negative electrode material.

[0013] In an optional embodiment, the particle size of the small-particle porous carbon reaction raw material is 0 to 15 μm, and is not 0, and the specific surface area is 500 to 2500 m 2 / g.

[0014] In an optional embodiment, in step 2, the volume flow ratio of the silicon source to the carrier gas is 1:1 to 1:25; the deposition temperature is 400 to 800° C., and the time is 0.5 to 5 hours; and the flow rate of the mixed gas in the reactor is 0.001 to 10 m / s.

[0015] In step 3, the volume flow ratio of the carbon source to the carrier gas is 1:1 to 1:40; the deposition temperature is 450 to 750° C., the reaction time is 1 to 6 hours; and the flow rate of the mixed gas in the reactor is 0.001 to 10 m / s.

[0016] In an optional embodiment, the carbon source is selected from at least one of C1-C10 alkanes, C2-C10 alkenes, C2-C10 alkynes and C6-C12 aromatic hydrocarbons;

[0017] Preferably, the carbon source is selected from any one or more of methane, ethane, ethylene, acetylene and propylene.

[0018] In an optional embodiment, the silicon source includes any one or more of monosilane, disilane, hexamethyldisilane, chlorosilane and tetrafluorosilane.

[0019] In an optional embodiment, the mass ratio of porous carbon to silicon in the silicon-based intermediate obtained in step 2 is 1 to 800.

[0020] In an optional embodiment, the mass of the deposited carbon of the silicon-carbon negative electrode material obtained in step 3 accounts for 0 to 30% of the total mass, and is not 0.

[0021] In an optional embodiment, the stirred fluidized bed reactor is provided with a single-stage or multi-stage agitator; the stirring mode of the agitator is any one or a combination of mechanical stirring, magnetic stirring, gas stirring and hydraulic stirring, preferably mechanical stirring or magnetic stirring;

[0022] Among them, the agitator using the mechanical stirring method is provided with a stirring paddle; the installation form of the stirring paddle includes any one or a combination of vertical installation, horizontal installation, and inclined installation; the structural form of the stirring paddle includes one or more of anchor type, paddle type, turbine type, propulsion type and frame type.

[0023] Due to the application of the above technical solution, the present disclosure has the following advantages compared with the prior art:

[0024] The embodiment of the present invention performs silicon deposition and carbon deposition in a stirred fluidized bed reactor, so the preparation process is simple and reliable, the process flow is short, and it is conducive to industrial scale-up. The silicon loading of the obtained silicon-carbon negative electrode material is uniform, and the controllable adjustment of the silicon loading and carbon loading is achieved.

[0025] The porous carbon raw material used in the present invention has a skeleton effect, which effectively inhibits the expansion of the silicon material. Furthermore, it combines the high strength, toughness and high conductivity advantages of the carbon deposition material with the vapor deposition of silicon material with high specific capacity characteristics to form a load material, and solves the problem of Li15Si4 phase in the charge and discharge cycle of the existing silicon-carbon material. On the basis of improving the battery specific capacity, it ensures the safety, reliability and long-term stability of the battery during the charge and discharge process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0027] FIG1 is a process flow chart of a method for preparing a silicon-carbon negative electrode material according to an embodiment of the present invention;

[0028] FIG2 is a schematic diagram of a stirred fluidized bed reactor for fluidized silicon deposition reaction / carbon deposition reaction according to the present invention;

[0029] FIG3 is an operational diagram of the fluidized silicon deposition / fluidized carbon deposition reaction of the present invention;

[0030] FIG4 is a schematic diagram of the present invention for fluidized silicon deposition reaction and fluidized carbon deposition reaction in different stirred fluidized bed reactors. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0032] The present invention provides a fluidized large-scale preparation method of silicon-carbon negative electrode materials, as shown in FIG1 , comprising:

[0033] Step 1: Crushing the raw materials.

[0034] The porous carbon material is crushed, ground and sieved to obtain small-particle porous carbon reaction raw materials; wherein, the porous carbon material is prepared by the method described in patent CN202310413886.1 "A method for preparing porous carbon and a multi-stage fluidized bed reactor thereof".

[0035] In order to ensure that the pore structure of the porous carbon raw material is sufficiently developed so that the particles can be tightly bound after the silicon deposition and carbon deposition reactions, the particle size of the small-particle porous carbon reaction raw material is 0-15 μm, and not 0, preferably 3-8 μm, and the specific surface area is 500-2500 m 2 / g, preferably 1200 to 1800 m 2 / g.

[0036] Step 2: Fluidized silicon deposition reaction.

[0037] The small-particle porous carbon reaction raw materials are placed in a stirred fluidized bed reactor into which a mixture of silicon source and carrier gas is introduced to carry out chemical vapor silicon deposition to obtain a silicon-based intermediate; the stirred fluidized bed reactor is used to improve the uniformity of gas-solid contact and optimize the fluidization quality in the reactor.

[0038] The conditions of the stirred fluidized bed reactor include: a temperature of 300 to 1000° C. and a stirring speed of 1 to 240 r / min.

[0039] The stirred fluidized bed reactor is provided with a single-stage or multi-stage stirrer; the stirring mode of the stirrer is any one or a combination of mechanical stirring, magnetic stirring, gas stirring and hydraulic stirring, preferably mechanical stirring or magnetic stirring;

[0040] Among them, the agitator using the mechanical stirring method is provided with a stirring paddle; the installation form of the stirring paddle includes any one or a combination of vertical installation, horizontal installation, and inclined installation; the structural form of the stirring paddle includes one or more of anchor type, paddle type, turbine type, propulsion type and frame type.

[0041] In order to ensure that silicon can be uniformly deposited on the porous carbon and to ensure a reasonably controllable silicon deposition amount and deposition rate, the volume flow ratio of the silicon source to the carrier gas is 1:1 to 1:25; preferably 1:5 to 1:10; the deposition temperature is 400 to 800°C, preferably 550 to 750°C; the time is 0.5 to 5 hours, preferably 3 to 4 hours; the flow rate of the mixed gas in the reactor is 0.001 to 10 m / s; preferably 0.05 to 0.1 m / s.

[0042] The silicon source includes one or more of monosilane, disilane, hexamethyldisilane, chlorosilane and tetrafluorosilane.

[0043] The mass ratio of porous carbon to silicon in the silicon-based intermediate is 1 to 800, for example, preferably 1 to 50.

[0044] Step 3: Fluidized carbon deposition reaction.

[0045] A mixture of a carbon source and a carrier gas is introduced into the silicon-based intermediate for chemical vapor carbon deposition; in order to improve the uniformity of carbon deposition on the particles and the controllability of the deposition rate during the deposition process, the volume flow ratio of the carbon source to the carrier gas is 1:1 to 1:40; preferably 1:5 to 1:20; the deposition temperature is 450 to 750° C., preferably 450 to 580° C.; the reaction time is 1 to 6 hours; preferably 4 to 6 hours; the flow rate of the mixed gas in the reactor is 0.001 to 10 m / s; preferably 0.05 to 0.1 m / s.

[0046] The carbon source is selected from at least one of C1-C10 alkanes, C2-C10 alkenes, C2-C10 alkynes, and C6-C12 aromatic hydrocarbons; preferably, the carbon source is selected from at least one of C1-C5 alkanes, C2-C5 alkenes, or C2-C5 alkynes; for example, the carbon source is selected from one or more of methane, ethylene, acetylene, and propylene. The reactor and operating steps for the fluidized silicon deposition reaction / carbon deposition reaction in steps 2 and 3 are shown in Figures 2 and 3, respectively.

[0047] The fluidized silicon deposition reaction and the carbon deposition reaction in step 2 and step 3 can be carried out in different stirred fluidized bed reactors (see FIG. 4 ), or can be carried out in the same stirred fluidized bed reactor.

[0048] An embodiment of the present invention provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials, which uses porous carbon with high specific surface area and fine particle size as raw material, and combines chemical vapor deposition of silicon and carbon deposition in a stirred fluidized bed reactor. The preparation process is simple and reliable, the process flow is short, and it is conducive to industrial scale-up. The silicon load of the obtained silicon-carbon negative electrode material is uniform, and the controllable adjustment of the silicon loading and carbon loading is achieved.

[0049] It should be noted that the fluidization recorded in the embodiments of the present invention refers to a chemical reaction carried out using a fluidized bed as a reactor, such as chemical vapor deposition, and the solid material particles are in a fluidized state during the reaction process. Macro-scale preparation refers to the large-scale industrial preparation of products. Macro-scale preparation can achieve high output while ensuring product quality.

[0050] The porous carbon raw material used in the present invention has a skeleton effect, which effectively inhibits the expansion of the silicon material. Furthermore, it combines the high strength, toughness and high conductivity advantages of the carbon deposition material with the vapor deposition of silicon material with high specific capacity characteristics to form a load material, and solves the problem of Li15Si4 phase in the charge and discharge cycle of the existing silicon-carbon material. On the basis of improving the battery specific capacity, it ensures the safety, reliability and long-term stability of the battery during the charge and discharge process.

[0051] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0052] Example 1

[0053] This embodiment provides a fluidized large-scale preparation method of silicon-carbon negative electrode materials, comprising:

[0054] The porous carbon material (prepared with coconut shell charcoal as raw material according to patent CN202310413886.1) was crushed, ground and sieved to obtain 100 kg of small-particle porous carbon reaction raw material with a particle size range of 0 to 15 μm (and not 0); and placed in a stirred fluidized bed reactor, argon was introduced as a carrier gas, and purged for 0.5 h. The temperature of the reactor was raised to 750 ° C, the stirring paddle of the reactor was turned on, and the speed was set to 60 r / min. Then, monosilane was used as the silicon source gas, and the volume flow ratio of monosilane gas to argon was adjusted to 1:10. The gas velocity in the fluidized bed reactor was maintained at 0.02 m / s, and silicon deposition was carried out. The reaction time was set to 2 h to obtain a silicon-based intermediate, and the silane gas was turned off.

[0055] Keep argon continuously purging the reactor, while adjusting the reactor temperature to 600 ° C, introduce propylene as the carbon source gas, and adjust the volume flow ratio of propylene gas to argon to 1:10, maintain the gas velocity in the fluidized bed reactor at 0.01 m / s, and fluidize the silicon-based intermediate obtained in the previous step by chemical vapor deposition method, and perform carbon deposition. The reaction time is set to 4h, turn off the propylene gas, turn off the reactor heating, and keep argon continuously purging the reactor until the reactor reaches room temperature to obtain a silicon-carbon negative electrode material.

[0056] Example 2

[0057] This embodiment provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of this preparation method is basically the same as that of Example 1, with the only difference being that: the reaction temperature of the fluidized silicon deposition is 550°C, the reaction time is 4 hours, the silicon source gas is chlorosilane, the volume flow ratio of chlorosilane gas to argon during the reaction is 1:25, and the gas velocity in the stirred fluidized bed reactor is maintained at 0.015 m / s; the fluidized carbon deposition is a reactor temperature of 550°C, a reaction time of 3 hours, and the other steps are the same.

[0058] Example 3

[0059] This embodiment provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of this preparation method is basically the same as that of Example 1, with the only difference being that the stirring paddle speed of the fluidized bed reactor is set to 240 r / min, the carbon source gas is ethane, and during the fluidized carbon deposition reaction, the volume flow ratio of ethane gas to argon is 1:15. The fluidized carbon deposition reactor temperature is 500°C, the reaction time is 2 h, and the gas velocity in the stirred fluidized bed reactor is maintained at 0.012 m / s. The other steps are the same.

[0060] Example 4

[0061] This embodiment provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of this preparation method is basically the same as that of Example 1, with the only difference being that: the reaction temperature of the fluidized silicon deposition is 500°C, the reaction time is 4 hours, the silicon source gas is chlorosilane, and the volume flow ratio of chlorosilane gas to argon during the reaction is 1:5, and the gas velocity in the stirred fluidized bed reactor is maintained at 0.012 m / s; the carbon source gas is ethane, and during the fluidized carbon deposition reaction, the volume flow ratio of ethane gas to argon is 1:8, the reactor temperature of the carbon deposition is 550°C, the reaction time is 2 hours, and the gas velocity in the stirred fluidized bed reactor is maintained at 0.008 m / s. The other steps are the same.

[0062] Example 5

[0063] This embodiment provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of this preparation method is basically the same as that of Example 1, with the only difference being that: the stirring paddle of the reactor is set to a speed of 30 r / min, chlorosilane is used as the silicon source gas, and the volume flow ratio of chlorosilane gas to argon is 1:8; during the fluidized carbon deposition reaction, acetylene is used as the carbon source gas, the reaction temperature is 580°C, and the volume flow ratio of acetylene gas to argon is adjusted to 1:40, the gas velocity in the stirred fluidized bed reactor is 0.015 m / s, the reaction time is set to 3.5 h, and the other steps are the same.

[0064] Example 6

[0065] This embodiment provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of this preparation method is basically the same as that of Example 1, with the only difference being that the stirring paddle of the reactor is set to a speed of 10 r / min, and the gas velocity in the stirred fluidized bed reactor during the fluidized silicon deposition reaction and the fluidized carbon deposition reaction is 0.015 m / s. The other steps are the same.

[0066] Comparative Example 1

[0067] This comparative example provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The preparation method is basically the same as that in Example 1, with the only difference being that the particle size of the small-particle porous carbon reaction raw material is 15 to 30 μm, and the other steps are the same as those in Example 1.

[0068] Comparative Example 2

[0069] This comparative example provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of the preparation method is basically the same as that of Example 1, with the only difference being that: the fluidized silicon deposition reaction and the fluidized carbon deposition reaction use a fluidized bed reactor without a stirring function, and the particles in the fluidized bed reactor begin to fluidize when silicon source gas or carbon source gas is introduced. During the fluidized silicon deposition reaction, the volume flow ratio of silane gas to argon gas is adjusted to 1:15, and the gas velocity in the fluidized bed reactor is maintained at 0.05 m / s; during the fluidized carbon deposition reaction, the volume flow ratio of propylene gas to argon gas is adjusted to 1:5, and the gas velocity in the fluidized bed reactor is maintained at 0.008 m / s. The other steps are the same as in Example 1 and will not be repeated here.

[0070] Comparative Example 3

[0071] This comparative example provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The preparation method is basically the same as that in Example 1, with the following differences:

[0072] The fluidized silicon deposition reaction adopts a fluidized bed reactor without a stirring function. When the argon purge process is introduced before the silicon deposition reaction, the gas velocity in the bed is set to 0.02 m / s, so that the particles in the fluidized bed reactor are in a fluidized state. When the reactor temperature rises to 450°C, the volume flow ratio of silane gas to argon is adjusted to 1:12, and the gas velocity in the fluidized bed reactor is maintained at 0.04 m / s; the fluidized carbon deposition reaction is equipped with a stirred fluidized bed reactor, and the speed of the stirring paddle is set to 120 r / min. When the argon purge process is introduced before the carbon deposition reaction, the gas velocity in the bed is set to 0.02 m / s. When the reactor temperature is raised to 800°C, the particles in the stirred fluidized bed reactor are kept in a fluidized state. During the fluidized carbon deposition reaction, acetylene is used as the carbon source gas, and the volume flow ratio of propylene gas to argon is adjusted to 1:8, and the gas velocity in the fluidized bed reactor is maintained at 0.011 m / s. The other steps are the same as in Example 1 and are not repeated here.

[0073] Comparative Example 4

[0074] This comparative example provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The preparation method is basically the same as that in Example 1, with the following differences:

[0075] A stirred fluidized bed reactor was used for the silicon fluidized deposition reaction, and the speed of the stirring paddle was set to 150 r / min. During the silicon deposition reaction, chlorosilane was used as the silicon source gas, and the volume flow ratio of chlorosilane gas to argon was adjusted to 1:8, and the gas velocity in the fluidized bed reactor was maintained at 0.015 m / s. During the fluidized carbon deposition reaction, a fluidized bed reactor without a stirring function was used. During the carbon deposition reaction, ethane was used as the carbon source gas, and the volume flow ratio of ethane gas to argon was adjusted to 1:15, and the gas velocity in the fluidized bed reactor was maintained at 0.03 m / s. The other steps were the same as in Example 1 and will not be repeated here.

[0076] Comparative Example 5

[0077] This comparative example provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of the preparation method is basically the same as that of Example 1, with the only difference being that the reaction temperature of the fluidized silicon deposition is 350°C, the reaction time is 8 hours, the silicon source gas is chlorosilane, the volume flow ratio of argon gas to chlorosilane gas during the reaction is 1:10, and the gas velocity in the stirred fluidized bed reactor is maintained at 0.015 m / s; the other steps are the same.

[0078] Comparative Example 6

[0079] This comparative example provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of the preparation method is basically the same as that of Example 1, with the only difference being that the reaction temperature of the fluidized silicon deposition is 850°C, the reaction time is 2 hours, the silicon source gas is chlorosilane, the volume flow ratio of argon gas to chlorosilane gas during the reaction is 1:10, and the gas velocity in the stirred fluidized bed reactor is maintained at 0.015 m / s; the other steps are the same.

[0080] Comparative Example 7

[0081] This comparative example provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of the preparation method is basically the same as that of Example 1, with the only difference being that: during the fluidized silicon deposition reaction, the volume flow ratio of argon gas to chlorosilane gas is 1:30, and the gas velocity in the stirred fluidized bed reactor is maintained at 10.2 m / s; during the fluidized carbon deposition reaction, the volume flow ratio of argon gas to ethane gas is 1:45, and the gas velocity in the stirred fluidized bed reactor is maintained at 1.05 m / s. The other steps are the same.

[0082] Comparative Example 8

[0083] This comparative example provides a fluidized large-scale preparation method for silicon-carbon negative electrode materials. The operation of the preparation method is basically the same as that of Example 1, with the only difference being that: during the fluidized silicon deposition reaction, the volume flow ratio of argon gas to chlorosilane gas is 1:27, and the gas velocity in the stirred fluidized bed reactor is maintained at 1.1 m / s; during the fluidized carbon deposition reaction, the volume flow ratio of argon gas to ethane gas is 1:50, and the gas velocity in the stirred fluidized bed reactor is maintained at 10.1 m / s. The other steps are the same.

[0084] Test example

[0085] The silicon-carbon negative electrode materials prepared in Examples 1 to 6 and Comparative Examples 1 to 8 were used to make negative electrode sheets and assemble button-type half-cells. The test data are detailed in Table 1.

[0086] Table 1 Battery test results

[0087] As can be seen from Table 1, in Examples 1 to 6 and Comparative Examples 1 to 8, the silicon-carbon negative electrode materials provided by the embodiments of the present invention have a smaller expansion rate, a higher first coulombic efficiency, a higher first discharge capacity, and a higher capacity retention rate after 100 cycles, thereby improving the electrochemical performance of the materials and improving the cycle stability. The silicon deposition reaction and the carbon deposition reaction in Examples 1 to 6 both adopted a stirred fluidized bed reactor; the silicon deposition conditions and the carbon deposition conditions of Examples 2 to 4 were changed within the range defined by the embodiments of the present invention, which had little effect on the first discharge capacity and the capacity retention rate after 100 cycles of the obtained materials. The change in the silicon deposition conditions in Example 2 resulted in a significant increase in the expansion rate of the material; Examples 4 to 6 varied the stirring paddle speed settings in the silicon deposition and carbon deposition reactors, with Example 6 having the lowest stirring paddle speed of only 10 r / min. The resulting material had the highest expansion rate, and other electrochemical properties were basically stable. The particle size of the porous carbon reaction raw material used in Comparative Example 1 is 0-20 μm, the expansion rate of the obtained material is significantly increased, and the electrochemical performance and stability are reduced; the silicon deposition reaction and the carbon deposition reaction of Comparative Example 2 use a fluidized bed reactor without a stirring function, the silicon deposition reaction of Comparative Example 3 uses a fluidized bed reactor without a stirring function, and the carbon deposition reaction of Comparative Example 4 uses a fluidized bed reactor without a stirring function. It can be seen that when the stirring fluidized bed is not used during the reaction process, the capacity of the obtained material is significantly reduced, the capacity retention rate declines, and the expansion rate increases; Comparative Examples 5 and 6 are changes in the silicon deposition conditions of Example 1. The results show that, when the reaction conditions deviate from the range specified by the embodiments of the present invention, the electrochemical performance and cycle stability of the obtained material deteriorate; Comparative Examples 7 and 8 are changes in the fluidization conditions of silicon deposition and carbon deposition. The significant increase in the fluidizing gas velocity causes the fluidization state during the reaction process to change, which has the most significant negative impact on the electrochemical performance and cycle stability of the obtained material.

[0088] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention. Industrial Applicability

[0089] The fluidized large-scale preparation method for silicon-carbon anode materials disclosed herein involves depositing silicon and carbon in a stirred fluidized bed reactor. The preparation process is simple and reliable, with a short process flow that facilitates industrial scale-up. The resulting silicon-carbon anode material exhibits uniform silicon loading, enabling controllable regulation of both silicon and carbon loadings. The silicon-carbon anode material prepared using the fluidized large-scale preparation method disclosed herein can be applied to fields such as lithium-ion batteries requiring anode materials.

Claims

1. A fluidized large-scale preparation method for silicon-carbon negative electrode materials, characterized in that: include: Raw material crushing, fluidized silicon deposition reaction and fluidized carbon deposition reaction; The fluidized silicon deposition reaction and the fluidized carbon deposition reaction are carried out in a stirred fluidized bed reactor. The conditions of the stirred fluidized bed reactor include: a temperature of 300 to 1000° C. and a stirring speed of 1 to 240 r / min.

2. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to claim 1, characterized in that: The steps include: Step 1, raw material crushing: crushing, grinding and screening the porous carbon material to obtain small particles of porous carbon reaction raw material; Step 2, fluidized silicon deposition reaction: placing the small-particle porous carbon reaction raw material obtained in step 1 in a stirred fluidized bed reactor into which a mixture of carrier gas and silicon source gas is introduced to perform silicon deposition to obtain a silicon-based intermediate; Step 3, fluidized carbon deposition reaction: a mixed gas of carrier gas and carbon source is introduced into the silicon-based intermediate product obtained in step 2 to perform carbon deposition to obtain a silicon-carbon negative electrode material.

3. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to claim 2, characterized in that: In step 1, the particle size of the small-particle porous carbon reaction raw material is 0 to 15 μm, and is not 0, and the specific surface area is 500 to 2500 m 2 / g.

4. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to claim 2, characterized in that: In step 2, the volume flow ratio of the silicon source to the carrier gas is 1:1 to 1:25; the deposition temperature is 400 to 800° C., and the deposition time is 0.5 to 5 hours; and the flow rate of the mixed gas in the reactor is 0.001 to 10 m / s.

5. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to claim 2, characterized in that: In step 3, the volume flow ratio of the carbon source to the carrier gas is 1:1 to 1:40; the deposition temperature is 450 to 750° C., the reaction time is 1 to 6 hours; and the flow rate of the mixed gas in the reactor is 0.001 to 10 m / s.

6. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to any one of claims 2 to 5, characterized in that: The silicon source includes any one or more of monosilane, disilane, hexamethyldisilane, chlorosilane and tetrafluorosilane.

7. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to any one of claims 2 to 5, characterized in that: The carbon source is selected from at least one of C1-C10 alkanes, C2-C10 alkenes, C2-C10 alkynes and C6-C12 aromatic hydrocarbons.

8. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to claim 7, characterized in that: The carbon source is selected from any one or more of methane, ethane, ethylene, acetylene and propylene.

9. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to any one of claims 2 to 5, characterized in that: The mass ratio of porous carbon to silicon in the silicon-based intermediate obtained in step 2 is 1 to 800; the mass percentage of the deposited carbon in the silicon-carbon negative electrode material obtained in step 3 is 0 to 30% of the total mass, and is not 0.

10. The fluidized large-scale preparation method of silicon-carbon negative electrode material according to claim 1, characterized in that: The stirred fluidized bed reactor is provided with a single-stage or multi-stage stirrer; the stirring mode of the stirrer is any one or a combination of mechanical stirring, magnetic stirring, gas stirring and hydraulic stirring, preferably mechanical stirring or magnetic stirring; Among them, the agitator using the mechanical stirring is provided with a stirring paddle; the installation form of the stirring paddle includes any one or a combination of vertical installation, horizontal installation, and inclined installation; the structural form of the stirring paddle includes one or more of anchor type, paddle type, turbine type, propulsion type and frame type.

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