Hard carbon negative electrode material, and preparation method and use thereof

Abstract

The application provides a hard carbon negative electrode material and a preparation method and use thereof. The preparation method comprises the following steps: (1) mixing and reacting a conductive agent with an acid solution to obtain a surface-modified conductive agent; (2) heating and mixing the surface-modified conductive agent in step (1) with pitch material to obtain mixed particles; and (3) sequentially performing fluidized crosslinking, fluidized shaping and fluidized carbon coating on the mixed particles in step (2) to obtain the hard carbon negative electrode material. By mixing the surface-modified conductive agent with the pitch material and combining the fluidized treatment means, the hard carbon negative electrode material with regular spherical or spherical-like shape can be obtained without additional crushing and shaping processes, the electronic transmission rate of the material is effectively improved, the occurrence of material polarization is reduced, and the electrochemical performance of the material is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of anode materials, and relates to a hard carbon anode material, a preparation method thereof and uses thereof. Background Art

[0002] Graphite-based carbon materials have always dominated the entire lithium-ion battery anode material market due to advantages such as low cost and high energy density. They rely on the insertion and extraction of lithium ions in the graphite layer in an electrochemical system: 6C + xLi+ → Li x C6 (0 < x < 1), and the theoretical capacity is 372 mAh / g. However, there are defects such as low specific capacity, general rate performance and cycling performance, which limit the improvement of performance such as the energy density of lithium-ion batteries.

[0003] Hard carbon has higher capacity and excellent rate performance, and has always been a research hotspot. However, due to some defective structures in the material preparation process, the problem of low first efficiency exists in the first charge and discharge process of the material.

[0004] CN109742383A discloses a hard carbon anode material for sodium-ion batteries based on phenolic resin, a preparation method thereof and applications. The carbon anode material for sodium-ion batteries is a hard carbon material with an irregular block-shaped macroscopic morphology and a nanoscale microporous structure inside. Among them, the typical size of the irregular block is 10 - 200 μm; the pore diameter of the nanoscale microporous structure is less than 2 nm; the hard carbon material has a short-range ordered and long-range disordered microscopic structure feature; the hard carbon material uses phenolic resin as a precursor, and after being mixed with ethanol in a volume ratio of 2:1 - 8:1, it is subjected to hydrothermal curing treatment, and then mechanically pulverized, and then carbonized and cracked under the protection of an inert atmosphere. Using the above method, only hard carbon materials with irregular morphologies can be obtained. If regular morphologies are desired, additional shaping steps are required.

[0005] CN111244407 uses pitch to prepare a hard carbon precursor, bonds the hard carbon precursor and graphite with an additive, and performs a coating treatment on the surface to prepare a hard carbon / graphite composite material. CN1095992660A uses a carbon-containing biomass shell to prepare a hard carbon precursor, and then mixes the hard carbon precursor, graphite and an additive, and performs high-temperature carbonization to prepare a hard carbon / graphite composite material. Its first efficiency is improved, but the improvement in capacity is not obvious.

[0006] Therefore, how to improve the electrochemical performance of hard carbon anode materials is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a hard carbon anode material, its preparation method, and its applications. This invention, by mixing a surface-modified conductive agent with asphalt material and combining this with fluidization treatment, eliminates the need for additional crushing and shaping processes, thereby obtaining a hard carbon anode material with a regular spherical or near-spherical shape. This effectively improves the electron transport rate of the material, reduces the occurrence of polarization, and enhances its electrochemical performance.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a hard carbon anode material, the method comprising the following steps:

[0010] (1) The conductive agent is mixed with an acid solution and reacted to obtain a surface-modified conductive agent;

[0011] (2) The surface-modified conductive agent described in step (1) is heated and mixed with asphalt material to obtain mixed particles;

[0012] (3) The mixed particles described in step (2) are sequentially subjected to fluidized crosslinking, fluidized shaping and fluidized carbon coating to obtain the hard carbon anode material.

[0013] In this invention, the fluidized crosslinking and fluidized shaping in step (3) are carried out in an oxygen-containing atmosphere, and the fluidized carbon coating is carried out in a protective atmosphere.

[0014] This invention obtains hard carbon anode materials with regular spherical or near-spherical shapes by mixing a surface-modified conductive agent with asphalt material and combining it with fluidization treatment without additional crushing and shaping processes. This effectively improves the electron transport rate of the material, reduces the occurrence of material polarization, and enhances the electrochemical performance of the material.

[0015] In this invention, the reaction of the conductive agent with the acid solution can increase the content of oxygen-containing functional groups such as hydroxyl or carboxyl groups on the surface of the conductive agent, thereby improving the surface activity of the material and facilitating the subsequent modification process with the asphalt material to achieve improvement in the electronic level of the material; in step (2), heating can gradually soften the asphalt material, and the asphalt can be further mixed evenly with the conductive agent as a modifier.

[0016] During fluidized crosslinking, the internal structure of asphalt particles changes. Some small-molecule aromatic structures volatilize under heat. Under the influence of oxygen, crosslinking can occur between the aromatic ring structures inside the asphalt material. Simultaneously, under the influence of oxygen-containing functional groups on the surface of the modified conductive agent, the aromatic ring structure on the asphalt surface and the modified conductive agent crosslink. Under the combined action of oxygen and the modifier, the asphalt structure rearranges, forming an isotropic amorphous carbon structure during subsequent carbonization, improving the material's fast-charging performance. The introduction of highly conductive carbon nanomaterials can improve the electron transport rate and effectively reduce the occurrence of material polarization. During fluidized shaping, the surface of the asphalt particles melts, and under the influence of strong airflow, the material is in a state of continuous motion. Therefore, the material surface undergoes a continuous shaping process, forming a spherical structure with a rounded surface. Fluidized carbon coating can further deposit a uniform amorphous carbon structure on the material surface, effectively reducing the specific surface area of ​​the material and improving its initial efficiency.

[0017] This invention achieves an integrated process for the preparation, shaping, and carbon coating of hard carbon anode materials, without the need for additional steps, completing the process in one step and simplifying the operation.

[0018] In this invention, surface modification of the conductive agent can effectively utilize the oxygen-containing functional groups on the surface of the conductive nanomaterial to crosslink the asphalt, thereby achieving the combination of the two.

[0019] Preferably, the acid solution in step (1) includes any one or a combination of at least two of sulfuric acid solution, nitric acid solution or hydrochloric acid solution.

[0020] In this invention, a strong acid is selected, which is more conducive to the surface modification of carbon nanomaterials.

[0021] Preferably, the mass concentration of the sulfuric acid solution is 30-80%, for example, 30%, 40%, 50%, 60%, 70% or 80%.

[0022] Preferably, the mass concentration of the nitric acid solution is 30-60%, for example, 30%, 40%, 50% or 60%.

[0023] Preferably, the mass concentration of the hydrochloric acid solution is 10-35%, for example, 10%, 20%, 25%, 30% or 35%.

[0024] Preferably, the mass ratio of the conductive agent to the volume ratio of the acid solution is (0.5-2):25 g / mL, for example, 0.5:25, 0.8:25, 1:25, 1.3:25, 1.8:25 or 2:25, etc.

[0025] In this invention, if the mass ratio of the conductive agent to the volume ratio of the acid solution is too small, i.e., the conductive agent dosage is too low, the acid treatment effect will be more severe, affecting the conductivity of the material. If it is too large, i.e., the conductive agent dosage is too high, it will not be conducive to the modification treatment of the material.

[0026] Preferably, the conductive agent includes any one or a combination of at least two of graphene, carbon nanotubes, or carbon nanofibers.

[0027] In this invention, the use of the above-mentioned conductive agent is more conducive to improving the conductivity inside the material. Compared with particulate conductive agents, the conductivity is superior.

[0028] Preferably, the mixing reaction in step (1) includes sequential stirring, wetting, washing and drying.

[0029] Preferably, the stirring and soaking time is 1 to 48 hours, for example, 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, or 48 hours.

[0030] Preferably, the stirring and impregnation temperature is 0 to 5°C, for example, 0°C, 1°C, 2°C, 3°C, 4°C, or 5°C.

[0031] Preferably, in step (2), the mass ratio of the surface-modified conductive agent to the asphalt material is (0.5-10):100, for example, 0.5:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100 or 10:100, etc.

[0032] In this invention, if the mass ratio of the surface-modified conductive agent to the asphalt material is too small, that is, if there is too little surface-modified conductive agent, it will not be conducive to improving the conductivity of the material. If the mass ratio is too large, it will lead to the agglomeration of conductive particles and increase the preparation cost of the material.

[0033] Preferably, the heating and mixing temperature in step (2) is 100 to 400°C, for example, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C or 400°C.

[0034] In this invention, heating and mixing can achieve uniform dispersion of asphalt material and conductive nanomaterial. If the temperature is too low, the softening effect of the asphalt material will be poor, resulting in uneven mixing. If the temperature is too high, too much volatilization of small molecules inside the asphalt will reduce the material yield and is not conducive to the formation of a good microstructure.

[0035] Preferably, the heating and mixing method in step (2) includes stirring.

[0036] Preferably, the stirring speed is 100-800 rpm, such as 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm or 800 rpm.

[0037] Preferably, the stirring time is 0.5 to 2 hours, for example, 0.5 hours, 1 hour, 1.5 hours or 2 hours.

[0038] Preferably, the softening point of the asphalt material is 40 to 300°C, such as 40°C, 50°C, 100°C, 150°C, 200°C, 250°C, or 300°C.

[0039] Preferably, the median particle size of the mixed particles in step (2) is 5 to 20 μm, such as 5 μm, 10 μm, 15 μm or 20 μm.

[0040] Preferably, the fluidized crosslinking temperature in step (3) is 150 to 300°C, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, or 300°C.

[0041] In this invention, if the fluidized crosslinking temperature is too low, it will not be conducive to the oxidative crosslinking reaction of the asphalt material. If the temperature is too high, the material surface will tend to be rounded, resulting in a reduction in the overall surface area of ​​the material and affecting the oxidative crosslinking effect of the material.

[0042] Preferably, the fluidization crosslinking time in step (3) is 4 to 12 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours.

[0043] Preferably, the heating rate of the fluidization shaping in step (3) is 0.5 to 3℃ / min, for example, 0.5, 1℃ / min, 1.5℃ / min, 2℃ / min, 2.5℃ / min or 3℃ / min.

[0044] Preferably, the fluidization temperature in step (3) is 400 to 600°C, such as 400°C, 430°C, 450°C, 480°C, 500°C, 530°C, 550°C, 580°C, or 600°C.

[0045] In this invention, if the fluidized bed forming temperature is too low, it will be detrimental to the forming of the asphalt material, while if the temperature is too high, it will make it difficult to control the forming structure, shorten the forming time, and cause partial coking, resulting in incomplete forming.

[0046] Preferably, the fluidization shaping time in step (3) is 1 to 5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours or 5 hours.

[0047] Preferably, the heating rate of the fluidized carbon coating in step (3) is 1 to 5 °C / min, for example 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min or 5 °C / min, for example 800 °C, 900 °C, 1000 °C, 1100 °C or 1200 °C.

[0048] Preferably, the temperature of the fluidized carbon coating in step (3) is 800 to 1200°C, such as 800°C, 900°C, 1000°C, 1100°C or 1200°C.

[0049] Preferably, the fluidized carbon coating time in step (3) is 2 to 6 hours, such as 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0050] As a preferred technical solution, the preparation method includes the following steps:

[0051] (1) The conductive agent and acid solution are stirred and soaked at 0-5℃ for 1-48h with a mass ratio of conductive agent to acid solution of (0.5-2):25g / mL, washed with water and dried to obtain a surface-modified conductive agent.

[0052] (2) The surface-modified conductive agent with a mass ratio of (0.5~10):100 and the asphalt material with a softening point of 40~300℃ are stirred at 100~400℃ and a stirring rate of 100~800rpm for 0.5~2h to obtain mixed particles with a median particle size of 5~20μm.

[0053] (3) The mixed particles described in step (2) are fluidized and crosslinked at 150-300℃ for 4-12 hours, then heated to 400-600℃ at a heating rate of 0.5-3℃ / min for fluidized shaping for 1-5 hours, and finally heated to 800-1200℃ at a heating rate of 1-5℃ / min for fluidized carbon coating for 2-6 hours to obtain the hard carbon anode material;

[0054] Wherein, the acid solution in step (1) includes sulfuric acid solution and / or hydrochloric acid solution, and the conductive agent includes any one or a combination of at least two of graphene, carbon nanotubes or carbon nanofibers.

[0055] In a second aspect, the present invention provides a hard carbon anode material, which is prepared by the preparation method of hard carbon anode material as described in the first aspect, and the morphology of the hard carbon anode material is spherical and / or quasi-spherical.

[0056] Preferably, the median particle size of the hard carbon anode material is 3 to 20 μm, such as 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm or 20 μm.

[0057] Preferably, the tap density of the hard carbon anode material is 0.7–1.0 g / cm³. 3 For example, 0.7g / cm 3 0.8g / cm 3 0.9g / cm 3 or 1g / cm 3 wait.

[0058] Thirdly, the present invention also provides a battery comprising the hard carbon negative electrode material as described in the second aspect, the battery comprising a lithium-ion battery and / or a sodium-ion battery.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] This invention, by mixing a surface-modified conductive agent with asphalt material and combining it with fluidization treatment, yields a hard carbon anode material with a regular spherical or near-spherical shape without the need for additional crushing and shaping processes. This effectively improves the electron transport rate of the material, reduces polarization, and enhances its electrochemical performance. The battery provided by this invention exhibits a lithium removal capacity of over 421 mAh / g at 0.1C, an initial efficiency of over 73%, a capacity retention rate of over 35% at 5C / 0.5C, and a capacity retention rate of over 70% after 200 cycles. Furthermore, within a narrower range (the ratio of conductive agent to acid solution, the mass ratio of conductive agent to asphalt material, and the fluidization crosslinking temperature are all within preferred ranges), the battery exhibits a lithium removal capacity of over 516 mAh / g at 0.1C, an initial efficiency of over 83%, a capacity retention rate of over 40% at 5C / 0.5C, and a capacity retention rate of over 83.3% after 200 cycles. Attached Figure Description

[0061] Figure 1 This is a SEM image of the hard carbon anode material provided in Example 1. Detailed Implementation

[0062] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0063] Example 1

[0064] This embodiment provides a method for preparing a hard carbon anode material, the method being as follows:

[0065] (1) Graphene was dispersed in a 50% sulfuric acid solution (the mass ratio of graphene to the volume of sulfuric acid solution was 1:25, that is, 1g of graphene corresponds to 25mL of sulfuric acid solution), stirred and soaked at 1℃ for 12h, washed with distilled water until the filtrate was neutral, filtered and dried thoroughly in an oven to obtain a surface-modified conductive agent.

[0066] (2) After the surface-modified conductive agent and coal tar pitch (softening point of 150℃) are mixed evenly at a mass ratio of 5:100, the mixture is stirred at 200℃ at a stirring rate of 450rpm for 1h, cooled, and crushed to obtain mixed particles with a median particle size of 15μm.

[0067] (3) Under an air atmosphere, the mixed particles described in step (2) are fluidized and crosslinked at 200°C for 6 hours, then heated to 500°C at a heating rate of 1°C / min for fluidized shaping for 2 hours. The air atmosphere is then switched to an argon atmosphere, acetylene is introduced, and the temperature is raised to 1200°C at a heating rate of 5°C / min for fluidized carbon coating for 3 hours, resulting in a surface morphology of regular spherical structures (e.g., ...). Figure 1 The hard carbon anode material shown is shown.

[0068] Example 2

[0069] This embodiment provides a method for preparing a hard carbon anode material, the method being as follows:

[0070] (1) Disperse carbon nanotubes in a 35% hydrochloric acid solution (the mass ratio of carbon nanotubes to the volume of hydrochloric acid solution is 0.5:25, that is, 0.5g of carbon nanotubes corresponds to 25mL of hydrochloric acid solution), stir and soak at 2℃ for 25h, wash with distilled water until the filtrate is neutral, filter and dry thoroughly in an oven to obtain a surface-modified conductive agent;

[0071] (2) After the surface-modified conductive agent and petroleum asphalt (softening point of 40℃) are mixed evenly at a mass ratio of 0.5:100, the mixture is stirred at 850 rpm for 0.5 h at 100℃, cooled, and crushed to obtain mixed particles with a median particle size of 8 μm.

[0072] (3) In an air atmosphere, the mixed particles described in step (2) are fluidized and crosslinked at 150°C for 12 hours, and then heated to 400°C at a heating rate of 0.5°C / min for fluidized shaping for 5 hours. Then, the air atmosphere is switched to an argon atmosphere, acetylene is introduced, and the temperature is raised to 1000°C at a heating rate of 3°C / min for fluidized carbon coating for 2.5 hours to obtain a hard carbon anode material with a regular spherical structure on the surface.

[0073] Example 3

[0074] This embodiment provides a method for preparing a hard carbon anode material, the method being as follows:

[0075] (1) Disperse carbon nanofibers in a 30% sulfuric acid solution (the mass ratio of carbon nanofibers to the volume of sulfuric acid solution is 2:25, that is, 2g of carbon nanofibers corresponds to 25mL of sulfuric acid solution), stir and soak at 1℃ for 6h, wash with distilled water until the filtrate is neutral, filter and dry thoroughly in an oven to obtain a surface-modified conductive agent.

[0076] (2) After the surface-modified conductive agent and coal tar pitch (softening point of 250℃) are mixed evenly at a mass ratio of 10:100, the mixture is stirred at 400℃ and 800rpm for 1.5h, cooled, and crushed to obtain mixed particles with a median particle size of 5μm.

[0077] (3) In an air atmosphere, the mixed particles described in step (2) are fluidized and crosslinked at 300°C for 6 hours, and then heated to 600°C at a heating rate of 1°C / min for fluidized shaping for 2 hours. Then, the air atmosphere is switched to an argon atmosphere, acetylene is introduced, and the temperature is raised to 1200°C at a heating rate of 5°C / min for fluidized carbon coating for 3 hours to obtain a hard carbon anode material with a regular spherical structure on the surface.

[0078] Example 4

[0079] The difference between this embodiment and embodiment 1 is that in step (1) of this embodiment, the mass ratio of carbon nanotubes to the volume ratio of sulfuric acid solution is 2.5:25 g / mL.

[0080] The remaining preparation methods and parameters are consistent with those in Example 1.

[0081] Example 5

[0082] The difference between this embodiment and embodiment 1 is that in step (2) of this embodiment, the mass ratio of the surface-modified conductive agent to the coal tar pitch is 12:100.

[0083] The remaining preparation methods and parameters are consistent with those in Example 1.

[0084] Example 6

[0085] The difference between this embodiment and embodiment 1 is that in step (3) of this embodiment, the fluidization crosslinking temperature is 130°C.

[0086] The remaining preparation methods and parameters are consistent with those in Example 1.

[0087] Comparative Example 1

[0088] The difference between this comparative example and Example 1 is that this comparative example does not perform step (1), that is, the graphene and coal tar pitch are directly mixed.

[0089] The remaining preparation methods and parameters are consistent with those in Example 1.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Example 1 is that the fluidized crosslinking in step (3) is not performed in this comparative example.

[0092] The remaining preparation methods and parameters are consistent with those in Example 1.

[0093] Comparative Example 3

[0094] The difference between this comparative example and Example 1 is that the fluidization shaping in step (3) is not performed in this comparative example.

[0095] The remaining preparation methods and parameters are consistent with those in Example 1.

[0096] Comparative Example 4

[0097] The difference between this comparative example and Example 1 is that acetylene gas is not introduced during the fluidized carbon coating process in step (3) of this comparative example.

[0098] The remaining preparation methods and parameters are consistent with those in Example 1.

[0099] Comparative Example 5

[0100] This comparative example provides a method for preparing a hard carbon anode material, the preparation method is as follows:

[0101] Using glucose as a raw material, glucose is dissolved in water and added to a polytetrafluoroethylene container. The container is then sealed and subjected to a hydrothermal reaction at 180°C for 6 hours. After washing and drying, the material is carbonized at 1000°C to obtain spherical hard carbon material.

[0102] The hard carbon anode material, conductive carbon black, SBR and CMC provided in Examples 1-6 and Comparative Examples 1-5 were mixed in a mass ratio of 94:2.5:2:1.5 to obtain an anode slurry, which was coated on the surface of a copper foil, dried and rolled to obtain an electrode sheet. A coin cell lithium-ion battery was obtained by using a lithium sheet as the counter electrode.

[0103] The batteries provided in Examples 1-6 and Comparative Examples 1-5 were subjected to powder and electrochemical performance tests.

[0104] The tap density test was conducted in accordance with GB / T5162-2006 / ISO3953:1993.

[0105] The morphological images were obtained using a scanning electron microscope (SU1510).

[0106] Electrochemical performance testing: The obtained hard carbon anode material was mixed with SBR, CMC and SP in a ratio of 94.5:2.5:1.5:1.5 and coated onto copper foil. After drying, rolling and cutting, it was prepared into an electrode sheet with a diameter of 12 mm. It was then assembled with a lithium metal sheet to form a coin cell. The electrolyte was a conventional lithium-ion battery electrolyte and the separator was a PP separator.

[0107] Battery capacity (delithiation capacity at 0.1C, voltage range 0.05–2V), first-cycle efficiency, rate capability (capacity retention at 5C / 0.5C), and cycle performance (capacity retention after 200 charge-discharge cycles at 0.5C / 0.5C), where 1C = 400 mAh / g, were tested using a Blue Electricity Tester. The results are shown in Table 1.

[0108] Table 1

[0109]

[0110] The data from Examples 1 and 4 show that when the mass-to-volume ratio of carbon nanotubes to sulfuric acid solution is too large, i.e., when too much conductive agent is added, it is not conducive to the later cross-linking of the material, which leads to a decrease in the tap density of the material, and the subsequent capacity utilization and cycle stability will also deteriorate.

[0111] The data results from Examples 1 and 5 show that an excessively high mass ratio of surface-modified conductive agent to coal tar pitch will result in uneven distribution of the conductive agent material. Furthermore, the introduction of too much conductive agent material with a large specific surface area will increase the specific surface area of ​​the material, reduce the initial efficiency, and affect the cycle performance.

[0112] The data results from Examples 1 and 6 show that if the temperature is too low during the fluidized crosslinking process, it is difficult to achieve effective crosslinking inside the material, which leads to a decrease in the material's cycle performance and rate performance.

[0113] The data results from Example 1 and Comparative Example 1 show that without surface modification of the conductive agent, the material will be unevenly dispersed inside, the conductive agent will reduce the tap density of the material, reduce the first-efficiency of the material, and affect the electrochemical performance of the material.

[0114] As can be seen from the data results of Example 1 and Comparative Examples 2-4, the absence of any step in step (3) will lead to the deterioration of battery performance.

[0115] The data results from Example 1 and Comparative Example 5 show that, compared with conventional methods for preparing hard carbon anode materials, the preparation method provided by this invention can effectively achieve the preparation of high-capacity, high-efficiency hard carbon materials. In contrast, the preparation method of Comparative Example 5 is complex and has a low yield, which leads to an increase in overall cost and is not conducive to production and large-scale application.

[0116] In summary, this invention, by mixing a surface-modified conductive agent with asphalt material and combining it with fluidization treatment, yields a hard carbon anode material with a regular spherical or near-spherical shape without the need for additional crushing and shaping processes. This effectively improves the electron transport rate of the material, reduces polarization, and enhances its electrochemical performance. The battery provided by this invention exhibits a lithium removal capacity of over 421 mAh / g at 0.1C, an initial efficiency of over 73%, a capacity retention rate of over 35% at 5C / 0.5C, and a capacity retention rate of over 70% after 200 cycles. Furthermore, within the preferred range (the ratio of conductive agent to acid solution, the mass ratio of conductive agent to asphalt material, and the fluidization crosslinking temperature are all within their optimal ranges), the battery exhibits a lithium removal capacity of over 516 mAh / g at 0.1C, an initial efficiency of over 83%, a capacity retention rate of over 40% at 5C / 0.5C, and a capacity retention rate of over 83.3% after 200 cycles.

[0117] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a hard carbon anode material, characterized in that, The preparation method consists of the following steps: (1) The conductive agent is mixed with an acid solution and reacted to obtain a surface-modified conductive agent; (2) The surface-modified conductive agent described in step (1) is heated and mixed with asphalt material to obtain mixed particles; (3) The mixed particles described in step (2) are sequentially subjected to fluidized crosslinking, fluidized shaping and fluidized carbon coating to obtain the hard carbon anode material; The hard carbon anode material has a spherical and / or near-spherical morphology. In step (1), the mass ratio of the conductive agent to the volume ratio of the acid solution is (0.5~2):25g / mL; In step (2), the mass ratio of the surface-modified conductive agent to the asphalt material is (0.5~10):100; The fluidized crosslinking temperature in step (3) is 150~300℃; The fluidization shaping temperature in step (3) is 400~600℃; The temperature of the fluidized carbon coating in step (3) is 800~1200℃.

2. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The acid solution in step (1) includes any one or a combination of at least two of sulfuric acid solution, nitric acid solution or hydrochloric acid solution.

3. The method for preparing the hard carbon anode material according to claim 2, characterized in that, The sulfuric acid solution has a mass concentration of 30-80%.

4. The method for preparing the hard carbon anode material according to claim 2, characterized in that, The mass concentration of the nitric acid solution is 30-60%.

5. The method for preparing the hard carbon anode material according to claim 2, characterized in that, The mass concentration of the hydrochloric acid solution is 10-35%.

6. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The conductive agent includes any one or a combination of at least two of graphene, carbon nanotubes, or carbon nanofibers.

7. The method for preparing the hard carbon anode material according to claim 1, characterized in that, Step (1) The mixing reaction includes stirring, wetting, washing and drying in sequence.

8. The method for preparing the hard carbon anode material according to claim 7, characterized in that, The stirring and soaking time is 1 to 48 hours.

9. The method for preparing the hard carbon anode material according to claim 7, characterized in that, The temperature for stirring and impregnation is 0~5℃.

10. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The heating and mixing temperature in step (2) is 100~400℃.

11. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The heating and mixing method in step (2) includes stirring.

12. The method for preparing the hard carbon anode material according to claim 11, characterized in that, The stirring speed is 100~800 rpm.

13. The method for preparing the hard carbon anode material according to claim 11, characterized in that, The stirring time is 0.5~2 hours.

14. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The softening point of the asphalt material is 40~300℃.

15. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The median particle size of the mixed particles in step (2) is 5~20μm.

16. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The fluidization crosslinking time in step (3) is 4~12h.

17. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The heating rate of the fluidization shaping in step (3) is 0.5~3℃ / min.

18. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The fluidization shaping time in step (3) is 1 to 5 hours.

19. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The heating rate of the fluidized carbon coating in step (3) is 1~5℃ / min.

20. The method for preparing the hard carbon anode material according to any one of claims 1-19, characterized in that, The fluidized carbon coating time in step (3) is 2~6 hours.

21. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The preparation method includes the following steps: (1) The conductive agent and acid solution are stirred and soaked at 0~5℃ for 1~48h with a mass ratio of conductive agent to acid solution of (0.5~2):25 g / mL, washed with water and dried to obtain the surface-modified conductive agent; (2) The surface-modified conductive agent with a mass ratio of (0.5~10):100 and the asphalt material with a softening point of 40~300℃ are stirred at 100~400℃ and a stirring rate of 100~800rpm for 0.5~2h to obtain mixed particles with a median particle size of 5~20μm. (3) The mixed particles described in step (2) are fluidized and crosslinked at 150~300℃ for 4~12h, then heated to 400~600℃ at a heating rate of 0.5~3℃ / min for fluidized shaping for 1~5h, and finally heated to 800~1200℃ at a heating rate of 1~5℃ / min for fluidized carbon coating for 2~6h to obtain the hard carbon anode material; Wherein, the acid solution in step (1) includes sulfuric acid solution and / or hydrochloric acid solution, and the conductive agent includes any one or a combination of at least two of graphene, carbon nanotubes or carbon nanofibers.

22. A hard carbon anode material, characterized in that, The hard carbon anode material is prepared by the preparation method of hard carbon anode material as described in any one of claims 1-21, and the morphology of the hard carbon anode material is spherical and / or quasi-spherical.

23. The hard carbon anode material according to claim 22, characterized in that, The tap density of the hard carbon anode material is 0.7~1.0 g / cm³. 3 .

24. A battery, characterized in that, The battery includes the hard carbon anode material as described in claim 22 or 23, and the battery includes a lithium-ion battery and / or a sodium-ion battery.

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