Preparation device and method of amorphous hard carbon negative electrode material

Abstract

The application discloses a preparation device of amorphous hard carbon negative material, comprising: a pre-pyrolysis system for pre-pyrolyzing biomass raw materials and synchronously modifying the surface of the biomass raw materials; a size-reducing distortion system for crushing the pre-pyrolyzed biomass materials and enhancing the lattice distortion degree of the crushed pre-pyrolyzed biomass materials to obtain a distorted amorphous precursor; and a crystal type rearrangement system for carbonizing and cracking the distorted amorphous precursor to obtain the amorphous hard carbon negative material. The application also provides a preparation method for preparing the amorphous hard carbon negative material by using the preparation device. The application can realize the efficient preparation of the amorphous hard carbon negative material while reducing the production energy consumption, improving the production efficiency and reducing the production cost, is beneficial to the large-scale production, and the amorphous hard carbon negative material has excellent comprehensive electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of battery materials, and particularly relates to an apparatus and method for preparing a negative electrode material. Background Technology

[0002] Since global lithium resources cannot simultaneously meet the demands of both the power battery and energy storage battery markets, sodium-ion batteries, with their advantages of widely distributed raw materials, abundant reserves, and lower costs, have gradually gained attention in the global energy storage market. Currently, anode materials applicable to sodium-ion batteries include carbon-based materials, titanium-based materials, alloy materials, and organic materials. Among these, amorphous hard carbon materials, a type of carbon-based material, exhibit superior sodium storage performance compared to traditional graphite materials. Furthermore, its readily available raw materials and low cost make it the most likely candidate material for large-scale commercialization of sodium-ion battery anode materials.

[0003] Amorphous hard carbon anode materials are difficult to graphitize, meaning they cannot be completely graphitized even at high temperatures (2800℃), exhibiting a microstructure of long-range disorder and short-range order. Simultaneously, hard carbon has a graphite interlayer spacing greater than 0.36 nm and possesses numerous carbon layer defects and pores, allowing for better insertion and extraction of sodium ions between carbon layers, resulting in a large number of active sodium storage sites and a high sodium storage capacity. Biomass feedstocks are widely distributed in nature, making biomass-based hard carbon materials a good choice for production. However, current biomass-based hard carbon materials still suffer from low initial coulombic efficiency and low specific capacity, which urgently need to be addressed.

[0004] To address the aforementioned issues, patent application CN113506868A discloses a non-metallic doped hard carbon anode material and its preparation method. Using waste biomass as a carbon source, the material is obtained by soaking in a solution of a non-metallic compound and mixing with an organic carbon source, followed by calcination. This material has a high specific capacity, but the preparation process is cumbersome and requires long-term heat treatment at different pyrolysis temperatures depending on the carbon source. This makes it difficult to precisely control the production process during large-scale production, resulting in high energy consumption and low production efficiency. Patent application CN115036473A discloses a sodium-ion battery anode material based on a hard carbon precursor and a doped phase, and its preparation method. This involves high-speed mixing and doping of biomass carbon with graphite or pitch followed by high-temperature carbonization to obtain a composite hard carbon material. While this method yields a hard carbon material with a high specific capacity, its initial efficiency is low, and the complex phase doping process is difficult to precisely control, thus hindering large-scale production of hard carbon materials.

[0005] As can be seen from the above, most of the currently disclosed preparation methods for biomass-based hard carbon anode materials involve modifying biomass feedstock precursors followed by high-temperature pyrolysis to obtain the hard carbon anode material. This preparation method suffers from problems such as low production efficiency, difficulty in large-scale production, and unsatisfactory electrochemical performance of the hard carbon material. In particular, issues such as low initial coulombic efficiency and low specific capacity cannot be effectively resolved simultaneously. Currently, there are few reports on preparation methods and devices for biomass-based hard carbon materials that improve upon the crystal structure characteristics of the materials. Developing new methods and devices for preparing biomass-based hard carbon anode materials based on the crystal structure characteristics of biomass hard carbon materials to achieve efficient and stable production of biomass-based hard carbon anode materials with high specific capacity and high initial coulombic efficiency is of practical significance. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the shortcomings and defects mentioned in the background art above, and to provide a preparation apparatus and method for amorphous hard carbon anode materials with high efficiency and high electrochemical performance. To solve the above technical problem, the technical solution proposed by this invention is as follows:

[0007] An apparatus for preparing amorphous hard carbon anode material includes:

[0008] Prepyrolysis system: used to prepyrolyze biomass raw materials and simultaneously modify the surface of the biomass raw materials to increase the disorder of the biomass raw materials to obtain prepyrolyzed biomass materials; the prepyrolysis system includes a modified pyrolysis chamber and a microwave plasma generator for heating the biomass raw materials and ionizing the modified atmosphere in the modified pyrolysis chamber to generate anions to modify the biomass raw materials;

[0009] Diameter reduction distortion system: used to crush the preheated biomass material and enhance the lattice distortion degree of the crushed preheated biomass material to obtain a distorted amorphous precursor; the diameter reduction distortion system includes a distortion chamber, and the distortion chamber is equipped with a crushing component;

[0010] Crystal rearrangement system: used to carbonize and pyrolyze the distorted amorphous precursor to obtain amorphous hard carbon anode material, wherein the crystal rearrangement system includes a crystal rearrangement chamber.

[0011] In the above-mentioned preparation apparatus, preferably, the microwave plasma generating component includes a plasma diffusion chamber and a microwave plasma generating source, the microwave plasma generating source is disposed on the plasma diffusion chamber, the plasma diffusion chamber is directly connected to the modified pyrolysis chamber, and a modified gas source is connected to the plasma diffusion chamber.

[0012] In the above-mentioned preparation apparatus, preferably, the plasma diffusion chamber is located above the modified pyrolysis chamber, and the two are separated by a porous partition.

[0013] In the above-mentioned preparation apparatus, preferably, the crushing component includes a stirring rod and a stirring medium, both of which are disposed in the distortion chamber.

[0014] In the above-mentioned preparation apparatus, preferably, the distortion chamber is located below the modified pyrolysis chamber and above the crystal rearrangement chamber, and the material falls from the modified pyrolysis chamber to the distortion chamber and then to the crystal rearrangement chamber by gravity; a screen is provided between the distortion chamber and the crystal rearrangement chamber.

[0015] Specifically, in this invention, the prepyrolysis system includes one inert gas source, one inorganic gas source, one organic gas source, one protective gas valve, one inert gas valve, one inorganic gas source valve, one organic gas source valve, one mixing chamber, one mixed gas valve, one microwave plasma generator, one set of prepyrolysis cooling water, one plasma diffusion chamber, one porous partition, one prepyrolysis insulation layer, one feed inlet, one modified pyrolysis chamber, one cyclone dust collector, and one vacuum pump. The specific connection methods of each component are as follows: Figure 1 As shown, dried biomass-based raw materials are added through the feed inlet. Inert gas, inorganic gas, and organic gas sources provide the protective atmosphere and modification gas required during prepyrolysis. A mixing chamber is located below the gas sources to mix the gases when multiple gases are used simultaneously, achieving better modification results. In this invention, argon (Ar) is used as the inert gas source, O2, N2, NH3, SO2, H2S, etc., can be used as the inorganic gas source, and CH4, CF4, SF6, CHF3, etc., can be used as the organic gas source. Furthermore, each of the inert gas, inorganic gas, and organic gas sources is controlled by a separate valve, and the mixing of the gases is controlled by an independent valve. A microwave plasma generator is used to generate microwaves, rapidly heating the biomass raw materials and causing prepyrolysis. Simultaneously, the plasma generated under microwave radiation ionizes the gases in the mixed atmosphere, producing anions, achieving efficient prepyrolysis of the biomass raw materials while simultaneously modifying the materials. The porous partition has uniformly distributed 1mm diameter pores, allowing the atmosphere in the plasma diffusion chamber to diffuse more evenly into the modified pyrolysis chamber. The pre-pyrolysis insulation layer uses a ceramic material with low thermal conductivity to reduce heat loss and maintain thermal stability. Pre-pyrolysis cooling water is used for water cooling protection of the pre-pyrolysis process system. Furthermore, a metal outer shell is placed around the pre-pyrolysis cooling water and pre-pyrolysis insulation layer to prevent microwave radiation from harming the surrounding environment and operators. In this invention, the porous partition material can be made of microwave-transparent quartz, and the pre-pyrolysis insulation layer material can be made of aluminosilicate fiberboard with low thermal conductivity. A vacuum pump is used for evacuating the plasma diffusion chamber and the modified pyrolysis chamber, ensuring the smooth progress of the preparation process. A cyclone dust collector is used to collect dust carried out from the modified pyrolysis chamber during the vacuuming process.

[0016] Specifically, in this invention, the diameter reduction distortion system includes one motor, one distortion chamber inlet, one distortion chamber, one set of stirring medium, one set of stirring rod, one maintenance window, and one screen. The volume of stirring medium added through the maintenance window does not exceed 1 / 4 of the distortion chamber volume. The pre-pyrolyzed biomass material falling into the diameter reduction distortion system from the distortion chamber inlet undergoes violent collisions and impacts with the stirring medium in the distortion chamber, driven by the high-speed rotation of the stirring rod driven by the motor, resulting in breakage. Simultaneously, the high energy from these frequent collisions and impacts causes lattice distortion of the pre-pyrolyzed biomass material's grains and increases lattice defects, achieving high distortion properties. The distorted amorphous precursor obtained after distortion treatment falls into the crystal rearrangement system through the screen arranged at the bottom of the diameter reduction distortion system for subsequent high-temperature crystal rearrangement. After the diameter reduction distortion process is completed, the stirring medium remains on the screen. For ease of cleaning and maintenance, a maintenance window is provided at the bottom of the diameter reduction distortion system for removing the stirring medium and screen, as well as cleaning the interior of the distortion chamber. In this invention, the stirring medium is preferably made of zirconia beads.

[0017] Specifically, in this invention, the crystal rearrangement system includes one crystal rearrangement chamber inlet, one set of crystal rearrangement chamber cooling water, one crystal rearrangement chamber, one crystal rearrangement insulation layer, one high-temperature resistant sample boat, and one discharge port. The distorted amorphous precursor falls into the crystal rearrangement system through the crystal rearrangement chamber inlet and undergoes crystal rearrangement to obtain amorphous hard carbon anode material, which is then removed through the discharge port. The crystal rearrangement insulation layer can be made of mullite, which can effectively reduce heat loss and save energy. A set of crystal rearrangement chamber cooling water is arranged outside the crystal rearrangement insulation layer for water-cooled protection of the system during the crystal rearrangement process. The crystal rearrangement chamber can be heated by an electrically conductive silicon molybdenum rod, achieving a maximum temperature of 1750℃. The contact interface between the inlet and the crystal rearrangement insulation layer is equipped with a sealing ring for sealing and to prevent oxidation of the sample at high temperatures. Meanwhile, cooling water is also provided at the sealing ring of the feed inlet to prevent the sealing ring from melting and to ensure the safety of operators.

[0018] As a general technical concept, the present invention also provides a method for preparing amorphous hard carbon anode materials using the above-described preparation apparatus, comprising the following steps:

[0019] S1: The biomass raw material is fed into the modified pyrolysis chamber, and the microwave plasma generator is activated to pre-pyrolyze and modify the biomass raw material, thereby increasing the disorder of the biomass raw material and obtaining pre-pyrolyzed biomass material.

[0020] S2: The preheated biomass material is sent to the distortion chamber, and the crushing component is started to crush the preheated biomass material, thereby increasing the degree of lattice distortion of the crushed preheated biomass material to obtain a distorted amorphous precursor.

[0021] S3: The distorted amorphous precursor is sent to the crystal rearrangement chamber and heated in an inert atmosphere to carbonize and decompose the distorted amorphous precursor to obtain an amorphous hard carbon anode material.

[0022] In the above preparation method, preferably, the frequency (referring to the frequency of the microwave plasma generator) of the microwave plasma generating component is controlled to be 915MHz-2.45GHz, and the power is controlled to be 200-1200W.

[0023] In the above preparation method, preferably, the degree of disorder DD of the pre-pyrolyzed biomass material is (I D1 +I D2 +I D3 +I D4 ) / I G , among which, I D1 Sp for preheating biomass materials 3 Hybridization intensity, I D2 To determine the bonding strength between the graphite lattice and polyenes and impurity ions in preheated biomass materials, I D3 To preheat the amorphous graphite lattice strength of biomass materials, I D4 To determine the surface defect strength of the graphite lattice in preheated biomass materials, I G Sp for preheating biomass materials 2 Hybridization intensity, and DD is controlled to be 1.6-2.0.

[0024] In the above preparation method, preferably, the particle size of the distorted amorphous precursor is controlled to be 200-500 mesh. The degree of lattice distortion of the distorted amorphous precursor is measured by the full width at half maximum (FWHM) of the (002) peak in the particle XRD pattern. Specifically, FWHM = K·D·sinq, where K is an empirical coefficient, D is the grain size, and q is the X-ray emission angle, and FWHM is controlled to be 0.12-0.15.

[0025] In the above preparation method, preferably, when heating under an inert atmosphere, the inert atmosphere is nitrogen or argon, the heating rate is controlled at 1-10℃ / min, the holding temperature is 1000-1600℃, and the holding time is 1-5h; the degree of amorphousness of the amorphous hard carbon anode material is measured by the degree of graphitization R, specifically, R = H / B, where H is the peak intensity of the (002) peak in the XRD pattern of the amorphous hard carbon anode material, B is the peak background intensity of the (002) peak in the XRD pattern of the amorphous hard carbon anode material, and R is controlled to be 4-6.

[0026] In the above preparation method, preferably, the biomass raw materials can be derived from commonly used biomass raw materials such as reeds, coconut shells, asphalt, bamboo, sugarcane bagasse, corn stalks, and bamboo shoots.

[0027] To elaborate, the preparation method of the amorphous hard carbon anode material of the present invention includes the following steps:

[0028] S1: The biomass raw material is placed in a forced-air drying oven and kept at a certain temperature for a certain time to dehydrate it before being used to prepare amorphous hard carbon anode material.

[0029] S2: The dried biomass feedstock is added to the modified pyrolysis chamber through the feed inlet. The vacuum pump is turned on to evacuate the plasma diffusion chamber and the modified pyrolysis chamber. The inert gas valve, inorganic gas source valve, and organic gas source valve corresponding to the inert gas source, inorganic gas source, and organic gas source, respectively, are opened sequentially. The corresponding gases enter the mixing chamber for homogenization. Then, the mixed gas valve is opened, allowing the homogenized gas to enter the plasma diffusion chamber. The preheating cooling water is turned on, and the frequency and power of the microwave plasma generator are adjusted to rapidly heat the biomass feedstock and induce preheating. Simultaneously, the plasma generated under microwave radiation ionizes the gases in the mixed atmosphere to produce anions, modifying the biomass feedstock during preheating to obtain preheated biomass material. After preheating is complete, the valve at the bottom of the modified pyrolysis chamber is opened, and the preheated biomass material falls into the distortion chamber through the distortion chamber inlet.

[0030] S3: In the diameter reduction and distortion stage, after prepyrolysis, stirring medium is added to the distortion chamber through the maintenance window. The amount of stirring medium added is 1 / 4 of the distortion chamber volume, and the particle size of the stirring medium is 0.5-1mm. The prepyrolyzed biomass material falls into the distortion chamber through the inlet under gravity. Driven by a rotating motor, the stirring rod drives the stirring medium and the prepyrolyzed biomass material to move at high speed, with the motor frequency controlled at a certain frequency. Due to the intense collisions and impacts caused by the high-speed movement of the stirring medium and the prepyrolyzed biomass material, the prepyrolyzed biomass material breaks down, and the degree of lattice distortion increases, resulting in prepyrolyzed biomass material with a higher degree of distortion. When the particle size of the distorted amorphous precursor obtained after distortion treatment falls below a certain particle size, the distorted amorphous precursor will continuously fall through the sieve into the crystal rearrangement chamber inlet.

[0031] S4: During the crystal rearrangement stage, the distorted amorphous precursor falls into the high-temperature resistant sample boat in the crystal rearrangement chamber through the inlet. Cooling water is introduced into the crystal rearrangement chamber, and the protective gas valve is opened to allow high-temperature protective gas to flow into the pores on the crystal rearrangement insulation layer at a certain flow rate. The temperature inside the crystal rearrangement chamber is controlled to rise to a certain temperature at a certain rate, held at that temperature for a certain time, and then cooled to room temperature. The high-temperature resistant sample boat is then removed from the outlet, yielding the biomass-based amorphous hard carbon anode material.

[0032] More specifically, the method includes the following steps:

[0033] S1: The biomass raw material is placed in a forced-air drying oven and dehydrated at a certain temperature for a certain time before being used to prepare amorphous hard carbon anode material. In this invention, the preferred dehydration temperature is 85-110℃, and the dehydration time is 12-48 hours.

[0034] S2: The electrochemical performance of amorphous hard carbon anode materials is largely influenced by the degree of disorder in the amorphous hard carbon precursor. Microwaves can rapidly heat biomass feedstocks, causing thermal decomposition of components such as cellulose, hemicellulose, and lignin. Simultaneously, the plasma generated by the microwave radiation and atmosphere can modify the pre-pyrolyzed biomass material produced by thermal decomposition, further enhancing its disorder. The degree of disorder (DD) of pre-pyrolyzed biomass material is an important parameter measuring the degree of order (or disorder) in the material's crystal structure. Specifically, the degree of disorder (DD) of pre-pyrolyzed biomass material = (I... D1 +I D2 +I D3 +I D4 ) / I G , among which, I D1 Sp for preheating biomass materials 3 Hybridization (edge ​​defect intensity of graphite lattice), I D2To determine the bonding strength between the graphite lattice and polyenes and impurity ions in preheated biomass materials, I D3 To preheat the amorphous graphite lattice strength of biomass materials, I D4 To determine the surface defect strength of the graphite lattice in preheated biomass materials, I G Sp for preheating biomass materials 2 Hybridization (graphitization) intensity. The greater the disorder of the pre-pyrolyzed biomass material, the higher the degree of disorder of the pre-pyrolyzed biomass material crystals, which means that it is easier to generate amorphous hard carbon anode materials during high-temperature pyrolysis, and ultimately there are more sodium storage active sites.

[0035] The dried biomass feedstock is added to the modified pyrolysis chamber through the feed inlet. The vacuum pump is activated to evacuate the plasma diffusion chamber and the modified pyrolysis chamber. The valves corresponding to the inert gas source, inorganic gas source, and organic gas source are opened sequentially, allowing the corresponding gases to enter the mixing chamber for homogenization. Then, the mixed gas valve is opened, allowing the homogenized gas to enter the plasma diffusion chamber. The preheating cooling water is turned on, and the frequency and power of the microwave plasma generator are adjusted to rapidly heat the biomass feedstock and induce preheating. Simultaneously, the plasma generated under microwave radiation ionizes the gases in the mixed atmosphere, producing anions. During preheating, the biomass-based carbon material is modified, resulting in preheated biomass material. After preheating, the valve at the bottom of the modified pyrolysis chamber is opened, allowing the preheated biomass material to pass through the distortion chamber inlet. Considering the energy consumption of the actual preparation process, the frequency of the microwave plasma generator is controlled at 915MHz-2.45GHz, and the power is controlled at 200-1200W, which can control the disorder of the preheated biomass material to be 1.6-2.0.

[0036] S3: The particle size of the material will greatly affect the pyrolysis process and efficiency. The stirring medium and pre-pyrolysis biomass material in the distortion chamber are driven by a motor to generate ultra-high speed rotation and violent collisions and impacts. The pre-pyrolysis biomass material will break down. At the same time, the ultra-high energy brought by the violent collisions and impacts will cause the size of the crystals of the pre-pyrolysis biomass material to change in the a, b and c axis directions, that is, lattice distortion will occur. Therefore, this step can promote the distortion and defect formation of the pre-pyrolysis biomass material, and at the same time complete the coarse crushing of the material, reduce the burden of subsequent fine crushing, and help improve production efficiency and reduce energy consumption. The degree of lattice distortion of the distorted amorphous precursor is measured by the full width at half maximum (FWHM) of the (002) peak in the particle XRD pattern. Specifically, FWHM = K·D·sinq, where K is an empirical coefficient, D is the grain size, and q is the X-ray emission angle. The narrower the full width at half maximum (FWHM) of the distorted amorphous carbon precursor, the larger the grain size of the distorted amorphous carbon precursor, the fewer the defects in the distorted amorphous carbon precursor, and the smaller the degree of distortion in the distorted amorphous carbon precursor.

[0037] Preheated biomass material falls into the distortion chamber under gravity. Driven by the high-speed rotation of the motor, the preheated biomass material undergoes high-energy high-speed collisions and impacts with the stirring medium. This process causes the preheated biomass material to break apart, simultaneously increasing the degree of lattice distortion, resulting in preheated biomass material with a high degree of distortion. When the particle size of the distorted amorphous precursor obtained after distortion treatment falls below a certain threshold, the distorted amorphous precursor continuously falls through the sieve into the inlet of the crystal rearrangement chamber. Considering the energy consumption of the actual preparation process, the motor frequency during the diameter reduction distortion process is controlled at 20-60Hz, and the sieve particle size is controlled at 200-500 mesh, which controls the FWHM of the distorted amorphous carbon precursor to be 0.12-0.15.

[0038] S4: During the high-temperature crystal rearrangement stage, the amorphous hard carbon anode material can be prepared by combining the principle of high-temperature pyrolysis of biomass materials. The distorted amorphous precursor obtained by efficient preheating and decomposition modification and diameter reduction distortion treatment will undergo a series of reactions such as dehydrogenation, degassing and condensation reaction as the holding temperature increases, but will retain the carbon atom skeleton structure and form a locally graphitized amorphous structure. Under this structural characteristic, the amorphous carbon material has a large number of defect sites and closed pores while possessing a honeycomb graphite layer structure, both of which can enhance the sodium storage capacity of the amorphous hard carbon anode material. The degree of amorphousness of the amorphous hard carbon anode material is measured by the degree of graphitization R. Specifically, R = H / B, where H is the peak intensity of the (002) peak in the XRD pattern of the amorphous hard carbon anode material, and B is the peak background intensity of the (002) peak in the XRD pattern of the amorphous hard carbon anode material. The smaller the R value of amorphous hard carbon anode materials, the smaller the degree of local graphitization and the greater the degree of amorphization; conversely, the larger the R value, the greater the degree of local graphitization and the smaller the degree of amorphization.

[0039] The distorted amorphous precursor falls into the high-temperature resistant sample boat at the bottom of the crystal rearrangement chamber through the inlet of the crystal rearrangement chamber. Cooling water is introduced into the crystal rearrangement chamber, and the protective gas valve is opened to allow high-temperature protective gas to pass through the pores on the crystal rearrangement insulation layer. The temperature inside the crystal rearrangement chamber is controlled to rise at a certain rate to the set holding temperature. After holding at this temperature for a certain time and then cooling to room temperature, the high-temperature resistant sample boat 30 is removed from the outlet, yielding the desired biomass-based amorphous hard carbon anode material. In the actual hard carbon preparation process, the inert protective atmosphere is nitrogen or argon, the heating rate is 1-10℃ / min, the holding temperature is 1000-1600℃, and the holding time is 1-5h, which can control the R-value of the biomass-based amorphous hard carbon anode material to be 4-6.

[0040] The pre-pyrolysis modification and diameter reduction distortion treatment steps of this invention have a significant synergistic effect, and the order of the process steps cannot be changed. Specifically, this invention first utilizes microwaves of varying lengths and frequencies to rapidly heat and pre-pyrolyze the biomass feedstock. The microwave radiation, combined with the reaction gas, generates plasma, achieving energy-efficient and high-performance pre-pyrolysis and modification of the biomass feedstock. Furthermore, under rapid microwave heating, the interior of the biomass feedstock quickly heats up, generating a large amount of gas. This gas escapes and forms numerous micropores, which is beneficial for the modification of carbon from pre-pyrolysis. However, these numerous pores cannot be completely fused during the subsequent high-temperature crystal rearrangement process, resulting in a large specific surface area of ​​the final product and reduced electrochemical performance. Therefore, in this invention, after pre-pyrolysis modification, a diameter reduction distortion treatment is added to destroy the numerous pores generated during efficient pre-pyrolysis, enhancing the distortion degree of pre-pyrolyzed carbon, thereby achieving the goal of reducing the specific surface area and enhancing the electrochemical performance of the final hard carbon product.

[0041] Compared with the prior art, the advantages of the present invention are as follows:

[0042] This invention relates to an amorphous hard carbon anode material based on the principle of biomass composition thermal decomposition-heteroatom doping modification-high-temperature graphitization transformation. It combines an efficient pre-pyrolysis-diameter reduction distortion-crystal rearrangement device for amorphous carbon anode materials. Simultaneously, while microwaves rapidly and efficiently raise the temperature to pre-carbonize the components of biomass such as cellulose, lignin, and hemicellulose through thermal decomposition, the plasma containing heteroatoms generated under microwave radiation achieves heteroatomation modification of the pre-pyrolyzed biomass material, effectively increasing the disorder level of the pre-pyrolyzed biomass material. Combined with a stirring medium, the crystal lattice of the pre-pyrolyzed biomass material is distorted, further enhancing the defect formation of the distorted amorphous precursor. This makes it easier to obtain a distorted amorphous precursor with a narrower scale distribution and superior performance. After passing through the subsequent crystal rearrangement device, the amorphous hard carbon anode material is obtained. This invention enables the efficient preparation of amorphous hard carbon anode materials while reducing production energy consumption, improving production efficiency, and lowering production costs, facilitating large-scale production. The amorphous hard carbon anode material achieves a first-charge specific capacity of 352.46 mAh·g at a 0.1C rate. -1 It has an initial efficiency of 88.99% and excellent overall electrochemical performance.

[0043] This invention relates to a highly efficient pre-pyrolysis-diameter reduction distortion-crystal rearrangement device for amorphous hard carbon anode materials. It is developed based on thermodynamic analysis, kinetic enhancement theory, dielectric heating theory, and plasma physics theory in the field of biomass-based amorphous hard carbon anode materials, combined with mechanical design and manufacturing fundamentals. The device adopts a top-down vertical construction structure, and the entire set of equipment boasts advantages such as small footprint, high integration, easy maintenance, simple operation, and high production efficiency. It can be used for the efficient preparation of various biomass-based amorphous hard carbon material precursors and amorphous hard carbon anode materials, effectively solving many problems in the electrochemical performance of current amorphous hard carbon materials, such as low initial coulombic efficiency and low specific capacity. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the apparatus for preparing the amorphous hard carbon anode material of the present invention.

[0046] Figure 2 This is a TEM image of the reed-based amorphous hard carbon anode material in Example 1.

[0047] Figure 3This is a charge-discharge curve of the reed-based amorphous hard carbon anode material in Example 1.

[0048] Legend:

[0049] 1. Inert gas source; 2. Inorganic gas source; 3. Organic gas source; 4. Protective gas valve; 5. Inert gas valve; 6. Inorganic gas source valve; 7. Organic gas source valve; 8. Mixing chamber; 9. Mixed gas valve; 10. Microwave plasma generator; 11. Preheating and cooling water; 12. Plasma diffusion chamber; 13. Porous partition; 14. Preheating and insulation layer; 15. Feed inlet; 16. Modified pyrolysis chamber; 17. Cyclone dust collector; 18. Vacuum pump; 19. Motor; 20. Distortion chamber inlet; 21. Distortion chamber; 22. Stirring medium; 23. Maintenance window; 24. Screen; 25. Crystal rearrangement chamber inlet; 26. Crystal rearrangement chamber cooling water; 27. Crystal rearrangement chamber; 28. Crystal rearrangement insulation layer; 29. ​​High-temperature resistant sample boat; 30. Discharge port; 31. Stirring rod. Detailed Implementation

[0050] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0051] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0052] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0053] Example 1:

[0054] like Figure 1 As shown, the apparatus for preparing amorphous hard carbon anode material in this embodiment includes:

[0055] Prepyrolysis system: used to prepyrolyze biomass raw materials and simultaneously modify the surface of the biomass raw materials to increase the disorder of the biomass raw materials to obtain prepyrolyzed biomass materials; the prepyrolysis system includes a modified pyrolysis chamber 16 and a microwave plasma generating component for heating the biomass raw materials and ionizing the modified atmosphere in the modified pyrolysis chamber 16 to obtain anions to modify the biomass raw materials;

[0056] Diameter reduction distortion system: used to crush preheated biomass materials and enhance the degree of lattice distortion of the crushed preheated biomass materials to obtain a distorted amorphous precursor; the diameter reduction distortion system includes a distortion chamber 21, and the distortion chamber 21 is equipped with crushing components.

[0057] Crystal rearrangement system: used to carbonize and pyrolyze distorted amorphous precursors to obtain amorphous hard carbon anode materials. The crystal rearrangement system includes a crystal rearrangement chamber 27.

[0058] In this embodiment, the microwave plasma generating assembly includes a plasma diffusion chamber 12 and a microwave plasma generating source 10. The microwave plasma generating source 10 is disposed on the plasma diffusion chamber 12. The plasma diffusion chamber 12 is directly connected to the modified pyrolysis chamber 16. A modified gas source is connected to the plasma diffusion chamber 12.

[0059] In this embodiment, the plasma diffusion chamber 12 is located above the modified pyrolysis chamber 16, and the two are separated by a porous partition 13.

[0060] In this embodiment, the crushing component includes a stirring rod 31 and a stirring medium 22, both of which are located inside the distortion chamber 21.

[0061] In this embodiment, the distortion chamber 21 is located below the modified pyrolysis chamber 16 and above the crystal rearrangement chamber 27. The material falls from the modified pyrolysis chamber 16 to the distortion chamber 21 and then to the crystal rearrangement chamber 27 by gravity. A screen 24 is provided between the distortion chamber 21 and the crystal rearrangement chamber 27.

[0062] Specifically, in this embodiment, the prepyrolysis system includes an inert gas source 1, an inorganic gas source 2, an organic gas source 3, an inert gas valve 5, an inorganic gas source valve 6, an organic gas source valve 7, a mixing chamber 8, a mixed gas valve 9, a microwave plasma generator 10, prepyrolysis cooling water 11, a plasma diffusion chamber 12, a porous partition 13, a prepyrolysis insulation layer 14, a feed inlet 15, a modified pyrolysis chamber 16, a cyclone dust collector 17, and a vacuum pump 18. The specific connection methods of each component are as follows: Figure 1 As shown.

[0063] The diameter reduction distortion system includes a motor 19, a distortion chamber inlet 20, a distortion chamber 21, a stirring medium 22, a stirring rod 31, a maintenance window 23, and a screen 24.

[0064] The crystal rearrangement system includes a crystal rearrangement chamber inlet 25, a crystal rearrangement chamber cooling water 26, a crystal rearrangement chamber 27, a crystal rearrangement insulation layer 28, a high-temperature resistant sample boat 29, and a discharge port 30.

[0065] This embodiment utilizes the above-described preparation apparatus for a method of preparing amorphous hard carbon anode materials, including the following steps:

[0066] 200g of reed biomass raw material, obtained by dehydration at 90℃ for 24h, was added to the modified pyrolysis chamber 16 through inlet 15. Vacuum pump 18 was turned on to evacuate the plasma diffusion chamber 12 and the modified pyrolysis chamber 16 to -0.1MPa. Then, inert gas valve 5, inorganic gas source valve 6, and organic gas source valve 7, corresponding to the inert gas source 1 (containing Ar), the inorganic gas source 2 (containing O2), and the organic gas source 3 (containing CH4), respectively, were opened sequentially. The corresponding gases entered the mixing chamber 8 for mixing. Then, the mixed gas valve 9 was opened, allowing the uniformly mixed gas to enter the plasma diffusion chamber 12. Preheating cooling water 11 was turned on, and the frequency of the microwave plasma generator 10 was adjusted to 2450MHz and the power to 400W. Under these conditions, the reed biomass is rapidly heated and prepyrolyzed. Simultaneously, the plasma generated by microwave radiation ionizes the gas in the mixed atmosphere, producing anions. During prepyrolysis, the prepyrolyzed reed-based carbon is modified to obtain prepyrolyzed reed-based carbon with a disorder degree of 1.78. After prepyrolysis, the prepyrolyzed reed-based carbon falls into the inlet 20 of the distortion chamber.

[0067] During the diameter reduction and distortion stage, after prepyrolysis, stirring medium 22 is added to distortion chamber 21 through maintenance window 23. The amount of stirring medium 22 added is 1 / 4 of the volume of distortion chamber 21, and the particle size of stirring medium 22 is 0.5-1mm. Prepyrolyzed reed-based carbon falls into distortion chamber 21 through distortion chamber inlet 20 under the action of gravity. Under the rotation of motor 19, stirring rod 31 drives stirring medium 22 and prepyrolyzed reed-based carbon to move at high speed. During this period, the frequency of motor 19 is controlled at about 50Hz. With the strong collisions and impacts caused by the high-speed movement of stirring medium 22 and prepyrolyzed reed-based carbon, the prepyrolyzed reed-based carbon breaks down and the degree of lattice distortion increases, resulting in a full width at half maximum (FWHM) of 0.14 for the (002) crystal plane peak of prepyrolyzed reed-based carbon. When the particle size of the distorted reed-based amorphous hard carbon precursor obtained after distortion treatment is less than 30 μm, the distorted reed-based amorphous carbon precursor will continuously pass through the sieve 24 and fall into the crystal rearrangement chamber inlet 25.

[0068] During the crystal rearrangement stage, the distorted reed-based amorphous hard carbon precursor falls into the high-temperature resistant sample boat 29 in the crystal rearrangement chamber 27 through the inlet 25. Cooling water is introduced into the crystal rearrangement chamber through the cooling water 26, and the protective gas valve 4 is opened to allow high-temperature protective gas to flow through the pores on the crystal rearrangement insulation layer 28 at a flow rate of 0.8 L / min. The temperature inside the crystal rearrangement chamber 27 is controlled to be raised to 1400℃ at a heating rate of 5℃ / min, held at this temperature for 2 hours, and then cooled to room temperature before being removed from the outlet 30, yielding a reed-based amorphous hard carbon anode material with a graphitization degree of 5.27.

[0069] The TEM image of the reed-based amorphous hard carbon anode material obtained in this embodiment is shown below. Figure 2 As shown, by Figure 2 It can be seen that the reed-based amorphous hard carbon anode material obtained in this embodiment exhibits long-range disorder and locally ordered graphite domains, which is a typical amorphous hard carbon material structure.

[0070] A reed-based amorphous hard carbon negative electrode material with a mass ratio of 90:5:5 was weighed, mixed with conductive carbon black Super-P and binder PVDF (polyvinylidene fluoride), and ground. The mixture was dissolved in NMP (N-methylpyrrolidone) as a solvent, and after thorough mixing, it was coated onto aluminum foil to form a negative electrode sheet. Using a sodium metal sheet as the positive electrode, a Whatman GF / D glass fiber separator, and a 1 mol / L NaPF6 electrolyte (DME = 100 vol%), a CR2032 coin cell was assembled in a vacuum glove box. The assembled coin cell was then subjected to electrochemical performance testing in the 0-2V range, and its charge-discharge curve is shown below. Figure 3 As shown, the specific capacity during the first charge is 352.46 mAh·g. -1 The first-efficacy rate was 88.99%.

[0071] Example 2:

[0072] The apparatus for preparing the amorphous hard carbon anode material in this embodiment is the same as that in Embodiment 1.

[0073] This embodiment utilizes the above-described preparation apparatus for a method of preparing amorphous hard carbon anode materials, including the following steps:

[0074] 200g of reed biomass raw material, obtained by dehydration at 90℃ for 24h, was added to the modified pyrolysis chamber 16 through inlet 15. Vacuum pump 18 was turned on to evacuate the plasma diffusion chamber 12 and the modified pyrolysis chamber 16 to -0.1MPa. Then, inert gas valve 5, inorganic gas source valve 6, and organic gas source valve 7, corresponding to the inert gas source 1 (containing Ar), the inorganic gas source 2 (containing O2), and the organic gas source 3 (containing CH4), respectively, were opened sequentially. The corresponding gases entered the mixing chamber 8 for mixing. Then, the mixed gas valve 9 was opened, allowing the uniformly mixed gas to enter the plasma diffusion chamber 12. Preheating cooling water 11 was turned on, and the frequency of the microwave plasma generator 10 was adjusted to 2450MHz and the power to 400W. Under these conditions, the reed biomass is rapidly heated and prepyrolyzed. Simultaneously, the plasma generated by microwave radiation ionizes the gas in the mixed atmosphere, producing anions. During prepyrolysis, the prepyrolyzed reed-based carbon is modified to obtain prepyrolyzed reed-based carbon with a disorder degree of 1.78. After prepyrolysis, the prepyrolyzed reed-based carbon falls into the inlet 20 of the distortion chamber.

[0075] During the diameter reduction and distortion stage, after prepyrolysis, stirring medium 22 is added to distortion chamber 21 through maintenance window 23. The amount of stirring medium 22 added is 1 / 4 of the volume of distortion chamber 21, and the particle size of stirring medium 22 is 0.5-1mm. Prepyrolyzed reed-based carbon falls into distortion chamber 21 through distortion chamber inlet 20 under the action of gravity. Under the rotation of motor 19, stirring rod 31 drives stirring medium 22 and prepyrolyzed reed-based carbon to move at high speed. During this period, the frequency of motor 19 is controlled at about 50Hz. With the strong collisions and impacts caused by the high-speed movement of stirring medium 22 and prepyrolyzed reed-based carbon, the prepyrolyzed reed-based carbon breaks down and the degree of lattice distortion increases, resulting in a full width at half maximum (FWHM) of 0.14 for the (002) crystal plane peak of prepyrolyzed reed-based carbon. When the particle size of the distorted reed-based amorphous hard carbon precursor obtained after distortion treatment is less than 30 μm, the distorted reed-based amorphous carbon precursor will continuously pass through the sieve 24 and fall into the crystal rearrangement chamber inlet 25.

[0076] During the crystal rearrangement stage, the distorted reed-based amorphous hard carbon precursor falls into the high-temperature resistant sample boat 29 in the crystal rearrangement chamber 27 through the inlet 25. Cooling water is introduced into the crystal rearrangement chamber through the cooling water 26, and the protective gas valve 4 is opened to allow high-temperature protective gas to flow through the pores on the crystal rearrangement insulation layer 28 at a flow rate of 0.8 L / min. The temperature inside the crystal rearrangement chamber 27 is controlled to be raised to 1200℃ at a heating rate of 5℃ / min, held at this temperature for 2 hours, and then cooled to room temperature before being removed from the outlet 30, yielding a reed-based amorphous hard carbon anode material with a graphitization degree of 5.01.

[0077] A reed-based amorphous hard carbon negative electrode material with a mass ratio of 90:5:5 was weighed, mixed with conductive carbon black Super-P and binder PVDF (polyvinylidene fluoride), and ground. The mixture was dissolved in NMP (N-methylpyrrolidone) as a solvent, and after thorough mixing, it was coated onto aluminum foil to form a negative electrode sheet. Using a sodium metal sheet as the positive electrode, a Whatman GF / D glass fiber separator, and a 1 mol / L NaPF6 electrolyte (DME = 100 vol%), a CR2032 coin cell was assembled in a vacuum glove box. The assembled coin cell was tested for electrochemical performance in the 0-2V range, and the initial charge specific capacity was 331.84 mAh·g. -1 The first-efficacy rate was 85.79%.

[0078] Example 3:

[0079] The apparatus for preparing the amorphous hard carbon anode material in this embodiment is the same as that in Embodiment 1.

[0080] This embodiment utilizes the above-described preparation apparatus for a method of preparing amorphous hard carbon anode materials, including the following steps:

[0081] 200g of reed biomass raw material, obtained by dehydration at 90℃ for 24h, was added to the modified pyrolysis chamber 16 through inlet 15. Vacuum pump 18 was turned on to evacuate the plasma diffusion chamber 12 and the modified pyrolysis chamber 16 to -0.1MPa. Then, inert gas valve 5, inorganic gas source valve 6, and organic gas source valve 7, corresponding to the inert gas source 1 (containing Ar), the inorganic gas source 2 (containing O2), and the organic gas source 3 (containing CH4), respectively, were opened sequentially. The corresponding gases entered the mixing chamber 8 for mixing. Then, the mixed gas valve 9 was opened, allowing the uniformly mixed gas to enter the plasma diffusion chamber 12. Preheating cooling water 11 was turned on, and the frequency of the microwave plasma generator 10 was adjusted to 2450MHz and the power to 400W. Under these conditions, the reed biomass is rapidly heated and prepyrolyzed. Simultaneously, the plasma generated by microwave radiation ionizes the gas in the mixed atmosphere, producing anions. During prepyrolysis, the prepyrolyzed reed-based carbon is modified to obtain prepyrolyzed reed-based carbon with a disorder degree of 1.78. After prepyrolysis, the prepyrolyzed reed-based carbon falls into the inlet 20 of the distortion chamber.

[0082] During the diameter reduction and distortion stage, after prepyrolysis, stirring medium 22 is added to distortion chamber 21 through maintenance window 23. The amount of stirring medium 22 added is 1 / 4 of the volume of distortion chamber 21, and the particle size of stirring medium 22 is 0.5-1mm. Prepyrolyzed reed-based carbon falls into distortion chamber 21 through distortion chamber inlet 20 under the action of gravity. Under the rotation of motor 19, stirring rod 31 drives stirring medium 22 and prepyrolyzed reed-based carbon to move at high speed. During this period, the frequency of motor 19 is controlled at about 30Hz. With the strong collisions and impacts caused by the high-speed movement of stirring medium 22 and prepyrolyzed reed-based carbon, the prepyrolyzed reed-based carbon breaks down and the degree of lattice distortion increases, resulting in a full width at half maximum (FWHM) of 0.12 for the (002) crystal plane peak of prepyrolyzed reed-based carbon. When the particle size of the distorted reed-based amorphous hard carbon precursor obtained after distortion treatment is less than 30 μm, the distorted reed-based amorphous carbon precursor will continuously pass through the sieve 24 and fall into the crystal rearrangement chamber inlet 25.

[0083] During the crystal rearrangement stage, the distorted reed-based amorphous hard carbon precursor falls into the high-temperature resistant sample boat 29 in the crystal rearrangement chamber 27 through the inlet 25. Cooling water is introduced into the crystal rearrangement chamber through the cooling water 26, and the protective gas valve 4 is opened to allow high-temperature protective gas to flow through the pores on the crystal rearrangement insulation layer 28 at a flow rate of 0.8 L / min. The temperature inside the crystal rearrangement chamber 27 is controlled to be raised to 1400℃ at a heating rate of 5℃ / min, held at this temperature for 2 hours, and then cooled to room temperature before being removed from the outlet 30, yielding a reed-based amorphous hard carbon anode material with a graphitization degree of 4.98.

[0084] A reed-based amorphous hard carbon negative electrode material with a mass ratio of 90:5:5 was weighed, mixed with conductive carbon black Super-P and binder PVDF (polyvinylidene fluoride), and ground. The mixture was dissolved in NMP (N-methylpyrrolidone) as a solvent, and after thorough mixing, it was coated onto aluminum foil to form a negative electrode sheet. Using a sodium metal sheet as the positive electrode and a Whatman GF / D glass fiber separator as the battery separator, and a 1 mol / L NaPF6 electrolyte (DME = 100 vol%), a CR2032 coin cell was assembled in a vacuum glove box. The assembled coin cell was subjected to electrochemical performance testing in the 0-2V range, and the initial charge specific capacity was 329.15 mAh·g. -1 The first-efficacy rate was 84.69%.

[0085] Comparative Example 1:

[0086] The apparatus for preparing the amorphous hard carbon anode material in this comparative example is the same as that in Example 1.

[0087] This comparative example utilizes the above-mentioned preparation apparatus to prepare amorphous hard carbon anode materials, and includes the following steps:

[0088] 200g of reed biomass raw material, obtained by dehydration at 90℃ for 24h, was added to the modified pyrolysis chamber 16 through inlet 15. Vacuum pump 18 was turned on to evacuate the plasma diffusion chamber 12 and the modified pyrolysis chamber 16 to -0.1MPa. Then, the inert gas valves 5 corresponding to the Ar-containing inert gas source 1 were opened sequentially, followed by the opening of the mixed gas valve 9, allowing the inert gas to enter the plasma diffusion chamber 12. Preheating cooling water 11 was turned on, and the frequency of the microwave plasma generator 10 was adjusted to 2450MHz and the power to 300W. Under these conditions, the reed biomass was rapidly heated and preheated. Simultaneously, the plasma generated under microwave radiation ionized the gas in the mixed atmosphere to produce anions. During preheating, the preheated reed-based carbon was modified to obtain preheated reed-based carbon with a disorder degree of 1.45. After preheating, the preheated reed-based carbon fell into the distortion chamber inlet 20.

[0089] During the diameter reduction and distortion stage, after prepyrolysis, stirring medium 22 is added to distortion chamber 21 through maintenance window 23. The amount of stirring medium 22 added is 1 / 4 of the volume of distortion chamber 21, and the particle size of stirring medium 22 is 0.5-1mm. Prepyrolyzed reed-based carbon falls into distortion chamber 21 through distortion chamber inlet 20 under the action of gravity. Under the rotation of motor 19, stirring rod 31 drives stirring medium 22 and prepyrolyzed reed-based carbon to move at high speed. During this period, the frequency of motor 19 is controlled at about 50Hz. With the strong collisions and impacts caused by the high-speed movement of stirring medium 22 and prepyrolyzed reed-based carbon, the prepyrolyzed reed-based carbon breaks down and the degree of lattice distortion increases, resulting in a full width at half maximum (FWHM) of 0.10 for the (002) crystal plane peak of prepyrolyzed reed-based carbon. When the particle size of the distorted reed-based amorphous hard carbon precursor obtained after distortion treatment is less than 30 μm, the distorted reed-based amorphous carbon precursor will continuously pass through the sieve 24 and fall into the crystal rearrangement chamber inlet 25.

[0090] During the crystal rearrangement stage, the distorted reed-based amorphous hard carbon precursor falls into the high-temperature resistant sample boat 29 in the crystal rearrangement chamber 27 through the inlet 25. Cooling water is introduced into the crystal rearrangement chamber through the cooling water 26, and the protective gas valve 4 is opened to allow high-temperature protective gas to flow through the pores on the crystal rearrangement insulation layer 28 at a flow rate of 0.8 L / min. The temperature inside the crystal rearrangement chamber 27 is controlled to be raised to 1400℃ at a heating rate of 5℃ / min, held at this temperature for 2 hours, and then cooled to room temperature before being removed from the outlet 30, yielding a reed-based amorphous hard carbon anode material with a graphitization degree of 7.04.

[0091] A reed-based amorphous hard carbon negative electrode material with a mass ratio of 90:5:5 was weighed, mixed with conductive carbon black Super-P and binder PVDF (polyvinylidene fluoride), and ground. The mixture was dissolved in NMP (N-methylpyrrolidone) as a solvent, and after thorough mixing, it was coated onto aluminum foil to form a negative electrode sheet. Using a sodium metal sheet as the positive electrode, a Whatman GF / D glass fiber separator, and a 1 mol / L NaPF6 electrolyte (DME = 100 vol%), a CR2032 coin cell was assembled in a vacuum glove box. The assembled coin cell underwent electrochemical performance testing in the 0-2V range, and the initial specific capacity was 293.37 mAh·g. -1 The first-efficacy rate was 80.18%.

[0092] Comparative Example 2:

[0093] The apparatus for preparing the amorphous hard carbon anode material in this comparative example is the same as that in Example 1.

[0094] This comparative example utilizes the above-mentioned preparation apparatus to prepare amorphous hard carbon anode materials, and includes the following steps:

[0095] 200g of untreated reed biomass raw material was placed in a high-temperature resistant sample boat 29 within the crystal rearrangement chamber 27. Cooling water 26 was opened to allow cooling water to flow into the chamber, and the protective gas valve 4 was opened to allow high-temperature protective gas to flow through the pores on the crystal rearrangement insulation layer 28 at a flow rate of 0.8L / min. The temperature inside the crystal rearrangement chamber 27 was raised to 1400℃ at a rate of 5℃ / min, held at that temperature for 2 hours, and then cooled to room temperature. The high-temperature resistant sample boat 29 was then removed from the outlet 30, yielding a reed-based amorphous hard carbon anode material with a graphitization degree of 10.21.

[0096] A reed-based amorphous hard carbon negative electrode material with a mass ratio of 90:5:5 was weighed, mixed with conductive carbon black Super-P and binder PVDF (polyvinylidene fluoride), and ground. The mixture was dissolved in NMP (N-methylpyrrolidone) as a solvent, and after thorough mixing, it was coated onto aluminum foil to form a negative electrode sheet. Using a sodium metal sheet as the positive electrode, a Whatman GF / D glass fiber separator, and a 1 mol / L NaPF6 electrolyte (DME = 100 vol%), a CR2032 coin cell was assembled in a vacuum glove box. The assembled coin cell was tested for electrochemical performance in the 0-2V range, and the initial charge specific capacity was 267.40 mAh·g. -1 The first-efficacy rate was 75.78%.

Claims

1. A method for preparing amorphous hard carbon anode materials using an apparatus for preparing amorphous hard carbon anode materials, characterized in that, The preparation apparatus includes: Prepyrolysis system: used to prepyrolyze biomass raw materials and simultaneously modify the surface of the biomass raw materials to increase the disorder of the biomass raw materials to obtain prepyrolyzed biomass materials; the prepyrolysis system includes a modified pyrolysis chamber (16) and a microwave plasma generating component for heating the biomass raw materials and ionizing the modified atmosphere in the modified pyrolysis chamber (16) to generate anions to modify the biomass raw materials; Diameter reduction distortion system: used to crush the preheated biomass material and enhance the degree of lattice distortion of the crushed preheated biomass material to obtain a distorted amorphous precursor; the diameter reduction distortion system includes a distortion chamber (21), and the distortion chamber (21) is provided with a crushing component; Crystal rearrangement system: used to carbonize and pyrolyze the distorted amorphous precursor to obtain amorphous hard carbon anode material, wherein the crystal rearrangement system includes a crystal rearrangement chamber (27). The preparation method includes the following steps: S1: The biomass raw material is fed into the modified pyrolysis chamber (16), and the microwave plasma generator is started to pre-pyrolyze and modify the biomass raw material, thereby increasing the disorder of the biomass raw material and obtaining pre-pyrolyzed biomass material. S2: The preheated biomass material is sent to the distortion chamber (21), the crushing component is started to crush the preheated biomass material, and the degree of lattice distortion of the crushed preheated biomass material is enhanced to obtain a distorted amorphous precursor. S3: The distorted amorphous precursor is sent to the crystal rearrangement chamber (27), and the distorted amorphous precursor is heated in an inert atmosphere to carbonize and decompose the distorted amorphous precursor to obtain an amorphous hard carbon anode material.

2. The preparation method according to claim 1, characterized in that, The microwave plasma generating assembly includes a plasma diffusion chamber (12) and a microwave plasma generating source (10). The microwave plasma generating source (10) is located on the plasma diffusion chamber (12). The plasma diffusion chamber (12) is directly connected to the modified pyrolysis chamber (16). A modified gas source is connected to the plasma diffusion chamber (12).

3. The preparation method according to claim 2, characterized in that, The plasma diffusion chamber (12) is located above the modified pyrolysis chamber (16), and the two are separated by a porous partition (13).

4. The preparation method according to claim 1, characterized in that, The crushing component includes a stirring rod (31) and a stirring medium (22), both of which are located inside the distortion chamber (21).

5. The preparation method according to claim 1, characterized in that, The distortion chamber (21) is located below the modified pyrolysis chamber (16) and above the crystal rearrangement chamber (27). The material falls from the modified pyrolysis chamber (16) to the distortion chamber (21) and then to the crystal rearrangement chamber (27) by gravity. A screen (24) is provided between the distortion chamber (21) and the crystal rearrangement chamber (27).

6. The preparation method according to claim 1, characterized in that, The frequency of the microwave plasma generating component is controlled between 915MHz and 2.45GHz, and the power is controlled between 200 and 1200W.

7. The preparation method according to claim 1, characterized in that, The disorder DD of the preheated biomass material = ( I D1 + I D2 + I D3 + I D4 ) / I G ,in, I D1 Sp for preheating biomass materials 3 Hybridization intensity I D2 To determine the bonding strength between the graphite lattice and polyenes and impurity ions in preheated biomass materials, I D3 To enhance the amorphous graphite lattice strength of preheated biomass materials, I D4 To measure the surface defect strength of the graphite lattice in preheating biomass materials, I G Sp for preheating biomass materials 2 Hybridization intensity, and DD is controlled to be 1.6-2.

0.

8. The preparation method according to claim 1, characterized in that, The particle size of the distorted amorphous precursor is controlled to be 200-500 mesh. The degree of lattice distortion of the distorted amorphous precursor is measured by the full width at half maximum (FWHM) of the (002) peak in the particle XRD pattern. Specifically, FWHM... =K·D·sinq , among which, among which K This is an empirical coefficient. D Grain size, q The X-ray emission angle is set, and the FWHM is controlled to be 0.12-0.

15.

9. The preparation method according to claim 1, characterized in that, When heating in an inert atmosphere, the inert atmosphere is nitrogen or argon. The heating rate is controlled at 1-10℃ / min, the holding temperature is 1000-1600℃, and the holding time is 1-5h. The degree of amorphousness of the amorphous hard carbon anode material is measured by the degree of graphitization R. Specifically, R=H / B, where H is the peak intensity of the (002) peak in the XRD pattern of the amorphous hard carbon anode material, and B is the peak background intensity of the (002) peak in the XRD pattern of the amorphous hard carbon anode material. R is controlled to be 4-6.

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