Carbon material, method for preparing the same, negative electrode material, and battery

Abstract

The application relates to a carbon material, a preparation method thereof, a negative electrode material and a battery. The carbon material has a rod-like structure, has pores and has a length-diameter ratio of 3-15. The carbon material has a rod-like structure, can reduce inter-particle pores, reduce particle breakage during pressing of an electrode sheet, and is beneficial to improving the compaction density, the energy density and the electrochemical performance of the material.

Description

Technical Field

[0001] This invention relates to the field of negative electrode materials technology, and in particular to carbon materials and their preparation methods, negative electrode materials, and batteries. Background Technology

[0002] Porous carbon anode materials are among the most critical materials for improving the cycle expansion performance of lithium-ion batteries. Currently used porous carbon anode materials typically have mesoporous or macroporous structures within their cavities or pores. This pore structure often leads to low efficiency and safety hazards when composited with active materials such as silicon, tin, lead, and sulfur. During the composite process, the active material cannot completely fill the macropores and mesopores in the porous carbon anode material, and the active material is difficult to distribute uniformly within the porous carbon's pore structure. This limits the improvement of the composite material's compaction density and energy density, and also results in uneven distribution of expansion tension during cycling, leading to the composite material's breakage and fragmentation, creating safety hazards. Furthermore, the numerous pores between the particles in porous carbon anode materials degrade the material's mechanical properties, causing it to fracture under stress during compaction and electrode fabrication, thus reducing the material's coulombic efficiency.

[0003] Therefore, how to improve the mechanical properties and energy density of anode materials and reduce particle breakage during electrode pressing is a problem that still needs to be solved. Summary of the Invention

[0004] The purpose of this application is to provide a carbon material and its preparation method, a negative electrode material, and a battery. The carbon material of this application has a rod-shaped structure, which can reduce the porosity between particles and reduce particle breakage during the electrode pressing process, which is beneficial to improving the compaction density, energy density and electrochemical performance of the material.

[0005] In a first aspect, this application provides a carbon material having a rod-like structure, having pores, and having an aspect ratio of 3 to 15.

[0006] In some embodiments, the length of the carbon material is 0.3 μm to 5 μm.

[0007] In some embodiments, the diameter of the carbon material is 0.1 μm to 3 μm.

[0008] In some embodiments, the total pore volume of the carbon material is 0.2 cm³. 3 / g~0.8cm 3 / g.

[0009] In some embodiments, the specific surface area of ​​the carbon material is 500 m². 2 / g~1600m2 / g.

[0010] In some embodiments, the average pore size in the carbon material is 0.8 nm to 2.5 nm.

[0011] In some embodiments, the pores in the carbon material include micropores, mesopores, and macropores.

[0012] In some embodiments, the pores in the carbon material include micropores, and the volume of the micropores accounts for 80% to 95% of the total pore volume.

[0013] In some embodiments, the pores in the carbon material include mesopores, and the volume of the mesopores accounts for 5% to 15% of the total pore volume.

[0014] In some embodiments, the pores in the carbon material include macropores, and the volume of the macropores accounts for 0% to 5% of the total pore volume.

[0015] In some embodiments, the carbon material contains oxygen, and the mass content of oxygen in the carbon material is 1% to 5.5%.

[0016] In some embodiments, the charging capacity of the battery assembled from the carbon material is 250 mAh / g to 400 mAh / g.

[0017] In some embodiments, the coulombic efficiency of the battery assembled from the carbon material is 40% to 55%.

[0018] Secondly, this application provides a negative electrode material, the negative electrode material comprising the carbon material and active substance described in the first aspect, the carbon material having pores, and at least a portion of the active substance filling the pores of the carbon material.

[0019] In some embodiments, the carbon content in the negative electrode material is 70% to 98% by mass.

[0020] In some embodiments, the active material includes silicon-based active particles.

[0021] In some embodiments, the active material includes silicon-based active particles, which include at least one of amorphous silicon, crystalline silicon, silicon oxide, silicon alloy, and a composite of crystalline and amorphous silicon.

[0022] In some embodiments, the active material includes silicon-based active particles with a median particle size of 0.85 nm to 2.45 nm.

[0023] In some embodiments, the specific surface area of ​​the negative electrode material is 0.5 m².2 / g~5m 2 / g.

[0024] In some embodiments, the pore volume of the negative electrode material is 0.001 cm³. 3 / g~0.020cm 3 / g.

[0025] In some embodiments, the compaction density of the negative electrode material is 0.90 g / cm³. 3 ~1.10g / cm 3 .

[0026] Thirdly, this application provides a method for preparing a carbon material, comprising the following steps:

[0027] An in-situ polymerization and co-precipitation reaction is carried out on a mixed solution containing inorganic zinc salt and polymer monomer to obtain a complex containing polymer and zinc hydroxide, wherein the concentration of the inorganic zinc salt is 0.045 mol / L to 0.400 mol / L.

[0028] The composite is dried to form a precursor containing the polymer and zinc oxide.

[0029] The precursor is subjected to step-heating heat treatment in an inert gas atmosphere to obtain a carbon material with a rod-shaped structure, wherein the aspect ratio of the carbon material is 3 to 15.

[0030] In some embodiments, the inorganic zinc salt includes at least one of zinc chloride, zinc nitrate, zinc acetate, zinc sulfate, zinc fluorosilicate, zinc fluoroborate, and zinc gluconate.

[0031] In some embodiments, the polymer monomer includes a first monomer and a second monomer.

[0032] In some embodiments, the polymer monomer includes a first monomer, which includes phenol and its derivatives, melamine and its derivatives, or benzoic acid and its derivatives.

[0033] In some embodiments, the polymer monomer includes a first monomer, which includes at least one of phenol, resorcinol, catechol, hydroquinone, phloroglucinol, p-aminophenol, and dopamine.

[0034] In some embodiments, the polymer monomer includes a first monomer, which includes at least one of melamine, benzomelamine, trichloromelamine, and hexamethylmelamine.

[0035] In some embodiments, the polymer monomer includes a first monomer, which includes at least one of benzoic acid, p-methylbenzoic acid, p-fluorobenzoic acid, and 3-chlorobenzoic acid.

[0036] In some embodiments, the polymer monomer includes a second monomer, which includes at least one of formaldehyde, furfural, acetaldehyde, propionaldehyde, and butyraldehyde.

[0037] In some embodiments, the mixed solution further includes a surfactant, the surfactant comprising at least one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium carboxymethyl cellulose, and polyvinylpyrrolidone.

[0038] In some embodiments, the mixed solution further includes a surfactant at a concentration of 0.10 mol / L to 0.15 mol / L.

[0039] In some embodiments, the mixed solution further includes a pH adjuster, which includes at least one of ammonia, sodium hydroxide, and potassium hydroxide.

[0040] In some embodiments, the pH of the mixed solution is 10 to 14.

[0041] In some embodiments, the reaction temperature of the in-situ polymerization reaction is 28°C to 50°C.

[0042] In some embodiments, the reaction time for the in-situ polymerization is 4 h to 12 h.

[0043] In some embodiments, the in-situ polymerization reaction is carried out under stirring, with the stirring rate controlled at 100 r / min to 1500 r / min.

[0044] In some embodiments, the specific steps of performing an in-situ polymerization reaction on a mixed solution containing inorganic zinc salt and polymer monomer to obtain a composite containing polymer and zinc hydroxide are as follows:

[0045] The polymer monomer, inorganic zinc salt, surfactant and ammonia are added to a solvent and mixed to obtain a mixed solution containing inorganic zinc salt and polymer monomer;

[0046] The mixed solution was subjected to in-situ polymerization and co-precipitation reactions, followed by solid-liquid separation to obtain a complex containing the polymer and zinc hydroxide.

[0047] In some embodiments, the solvent includes at least one of water, ethanol, methanol, and propanol.

[0048] In some embodiments, the solid-liquid separation includes at least one of filtration separation or centrifugal separation.

[0049] In some embodiments, the drying process is carried out at a temperature of 60°C to 90°C.

[0050] In some embodiments, the drying process takes 6 to 24 hours.

[0051] In some embodiments, the stepped heating heat treatment includes: placing the precursor at 300℃~400℃ for 1h~3h, then heating it to 600℃~900℃ for 1h~6h, and finally heating it to 950℃~1100℃ for 3h~6h.

[0052] In some embodiments, the heating rate of the stepped heating heat treatment is 1°C / min to 5°C / min.

[0053] In some embodiments, the inert gas atmosphere includes at least one of helium, nitrogen, and argon.

[0054] In some embodiments, the method further includes cooling, shaping, and sieving the product after stepped heating heat treatment, wherein the shaping includes at least one of mechanical crushing, grinding, ball milling, or air jet milling.

[0055] Fourthly, this application provides a battery comprising the carbon material described in the first aspect or the carbon material prepared by the method described in the third aspect.

[0056] Compared with the prior art, the technical solution of this application has at least the following beneficial effects:

[0057] The carbon material provided in this application has a rod-like structure with carbon particles stacked together. The small number of pores between particles reduces the porosity of the carbon material, improving its mechanical properties and reducing the probability of breakage during compaction. This contributes to increased compaction density, energy density, and electrochemical performance. By controlling the aspect ratio of the carbon material, it provides continuous axial electron transport paths and shorter radial ion diffusion paths, significantly improving the rate performance. The carbon material also possesses a large number of micropores, which, during composite formation with active materials, effectively utilize the chemical vapor permeation advantage of these micropores. This facilitates the uniform and efficient distribution of active materials within the pores, promoting the uniform dispersion of expansion stress and reducing the splitting and breakage of the anode material. This further enhances the compaction density and energy density of the anode material.

[0058] The negative electrode material provided in this application includes a carbon material with pores, mainly micropores. Silicon-based active particles fill the pores of the carbon material, which helps to improve the compaction density and energy density of the negative electrode material. At the same time, the silicon-based active particles can be uniformly distributed in the pores of the carbon material, which helps to improve the uniformity of the expansion tension distribution during the cycling process of the negative electrode material, reduce the splitting and breakage of the negative electrode material, and reduce the safety hazards of the negative electrode material.

[0059] The method for preparing carbon materials provided in this application involves in-situ polymerization of a mixed solution containing inorganic zinc salt and polymer monomers. During the in-situ polymerization process, the inorganic zinc salt in the solution precipitates to form zinc hydroxide, while the polymer monomers polymerize to form a polymer. The polymer and zinc hydroxide co-precipitate, generating a composite containing both polymer and zinc hydroxide. Furthermore, the aspect ratio of the carbon material is controlled by adjusting the concentration of the inorganic zinc salt in the mixed solution, thereby controlling the carbon material to have a rod-like structure. The composite is then dried. During the drying process, the zinc hydroxide decomposes to form zinc oxide with a rod-like structure, while the polymer particles are stacked and arranged using the zinc oxide as a template. A precursor containing polymer and zinc oxide is formed into a rod-shaped structure. The precursor is subjected to step-by-step heat treatment in an inert gas atmosphere. During the heat treatment, the structure of the rod-shaped precursor can be initially solidified, reducing the possibility of damage to the rod-shaped structure due to excessively rapid heating. Then, carbonization treatment is carried out at a higher temperature. During the high-temperature carbonization process, the polymer in the precursor decomposes to form a carbon material containing zinc oxide. Then, the zinc oxide is partially reduced to elemental zinc by the carbon in the carbon material. Finally, the zinc vapor is released from the interior of the carbon material at high temperature. The zinc vapor can act as a pore-forming agent to form uniform pores in the carbon material. The pores extend from the interior of the carbon material to the surface of the carbon material, thereby forming a porous rod-shaped carbon material. Attached Figure Description

[0060] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0061] Figure 1 This is a schematic diagram of the structure of the carbon material provided in the embodiments of this application;

[0062] Figure 2 This is a process flow diagram of carbon material preparation provided in the embodiments of this application;

[0063] Figure 3 This is a scanning electron microscope image of the carbon material provided in Example 1 of this application;

[0064] Figure 4 This is a scanning electron microscope image of the carbon material provided in Embodiment 2 of this application;

[0065] Figure 5 A scanning electron microscope image of the carbon material provided in Comparative Example 1 of this application;

[0066] Figure 6 A scanning electron microscope image of the carbon material provided in Comparative Example 2 of this application;

[0067] Figure 7 This is a pore size distribution diagram of the carbon material provided in Embodiment 1 of this application;

[0068] Figure 8 This is a pore size distribution diagram of the carbon material provided in Embodiment 2 of this application;

[0069] Figure 9 A pore size distribution diagram of the carbon material provided in Comparative Example 1 of this application;

[0070] Figure 10 The pore size distribution diagram of the carbon material provided in Comparative Example 2 of this application. Detailed Implementation

[0071] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0072] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0073] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0074] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0075] Firstly, such as Figure 1 As shown, this application provides a carbon material with a rod-like structure, pores, and an aspect ratio of 3 to 15.

[0076] The carbon material provided in this application has a rod-like structure with carbon particles stacked together. The low porosity between these particles reduces the porous structure, improving the mechanical properties of the carbon material and decreasing the probability of breakage during compaction. This contributes to higher compaction density, energy density, and electrochemical performance. By controlling the aspect ratio, it provides continuous axial electron transport paths and shorter radial ion diffusion paths, significantly enhancing the rate performance. The carbon material's numerous micropores effectively utilize the chemical vapor permeation advantage during composite formation with active materials. This facilitates the uniform and efficient distribution of active materials within the pores, promoting uniform dispersion of expansion stress and reducing the splitting and breakage of the anode material. This further contributes to higher compaction density and energy density. Axial direction refers to the length of the carbon material, and radial direction refers to its diameter.

[0077] Specifically, the aspect ratio of the carbon material can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, etc., and is not limited here. Preferably, the aspect ratio of the carbon material is 5 to 10.

[0078] In some embodiments, the length of the carbon material is 0.3 μm to 5 μm, specifically 0.3 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm, etc., and of course, other values ​​within the above range are also possible, and are not limited here. Preferably, the length of the carbon material is 1 μm to 3 μm.

[0079] In some embodiments, the diameter of the carbon material is 0.1 μm to 3 μm, specifically 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, etc., and of course, other values ​​within the above range are also possible, and are not limited here. Preferably, the diameter of the carbon material is 0.3 μm to 0.5 μm.

[0080] In some embodiments, the total pore volume of the carbon material is 0.2 cm³. 3 / g~0.8cm 3 / g. The total pore volume of the carbon material can specifically be 0.2cm³. 3 / g, 0.3cm 3 / g, 0.4cm 3 / g, 0.5cm 3 / g, 0.6cm 3 / g, 0.7cm 3 / g or 0.8cm 3 / g, etc., are not limited here. Preferably, the total pore volume of the carbon material is 0.5cm³. 3 / g~0.8cm 3 / g.

[0081] In some embodiments, the specific surface area of ​​the carbon material is 500 m². 2 / g~1600m 2 / g. The specific surface area of ​​carbon materials can specifically be 500m². 2 / g、600m 2 / g、700m 2 / g、800m 2 / g、900m 2 / g, 1000m 2 / g、1100m 2 / g、1200m 2 / g、1300m 2 / g, 1400m 2 / g, 1500m 2 / g or 1600m 2 / g, etc., and of course, other values ​​within the above range are also possible, and are not limited here. Preferably, the specific surface area of ​​the carbon material is 600m². 2 / g~900m 2 / g.

[0082] In some embodiments, the average pore size of the carbon material is 0.8 nm to 2.5 nm, specifically 0.8 nm, 0.9 nm, 1 nm, 1.1 nm, 1.3 nm, 1.5 nm, 1.6 nm, 1.8 nm, 2 nm, 2.3 nm, or 2.5 nm, etc., and of course, other values ​​within the above range are also possible, and are not limited here. Preferably, the average pore size of the carbon material is 1 nm to 1.5 nm.

[0083] In some embodiments, the pores in the carbon material include micropores, mesopores, and macropores.

[0084] In some embodiments, the pores in the carbon material include micropores, and the volume of the micropores accounts for 80% to 95% of the total pore volume. Specifically, this can be 80%, 81%, 83%, 85%, 87%, 90%, 91%, 92%, 93%, 94%, or 95%, etc., and other values ​​within the above range are also possible and are not limited here. Understandably, controlling the volume percentage of micropores in the carbon material within the above range improves the uniformity of the composite between the carbon material and the active material, allowing the active material to be uniformly distributed in the pore structure of the carbon material during the composite process. This enhances the uniformity of the expansion tension distribution during the cycling process of the negative electrode material, reduces the splitting and breakage of the negative electrode material, and lowers the safety hazards of the negative electrode material. Simultaneously, the microporous structure of the carbon material can be filled as completely as possible by the active material, which is beneficial to improving the compaction density and energy density of the negative electrode material. Preferably, the volume percentage of the micropores in the carbon material is 90% to 95% of the total pore volume.

[0085] In some embodiments, the pores in the carbon material include mesopores, and the volume of the mesopores accounts for 5% to 15% of the total pore volume. Specifically, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%, etc., and other values ​​within the above range are also possible and are not limited here. Preferably, the volume of the mesopores in the carbon material accounts for 5% to 10% of the total pore volume.

[0086] In some embodiments, the pores in the carbon material include macropores, and the volume of the macropores accounts for 0% to 5% of the total pore volume. Specifically, it can be 0%, 0.5%, 1%, 1%, 3%, 4%, or 5%, or other values ​​within the above range, which are not limited here. Preferably, the volume of the macropores in the carbon material accounts for 0% to 1% of the total pore volume.

[0087] In some embodiments, the carbon material contains oxygen, and the mass content of oxygen in the carbon material is 1% to 5.5%, specifically 1%, 1.2%, 1.5%, 1.8%, 2%, 2.4%, 2.6%, 2.9%, 3%, 3.5%, 4%, 4.5%, 5%, 5.1%, 5.2%, 5.3%, or 5.5%, etc., and of course, other values ​​within the above range are also possible, and are not limited here. Controlling the mass content of oxygen in the carbon material within the above range is beneficial to improving the conductivity of the carbon material. Preferably, the mass content of oxygen in the carbon material is 1% to 4.2%.

[0088] In some embodiments, the charging capacity of the battery assembled from the carbon material is 250 mAh / g to 400 mAh / g, specifically 250 mAh / g, 260 mAh / g, 280 mAh / g, 300 mAh / g, 320 mAh / g, 330 mAh / g, 350 mAh / g, 360 mAh / g, 370 mAh / g, 380 mAh / g, 390 mAh / g, or 400 mAh / g, etc., and is not limited thereto. Preferably, the charging capacity of the carbon material is 320 mAh / g to 390 mAh / g.

[0089] In some embodiments, the coulombic efficiency of the battery assembled from the carbon material is 40% to 55%, specifically 40%, 43%, 45%, 48%, 50%, 51%, 52%, 53%, 54%, or 55%, etc., and of course, other values ​​within the above range are also possible, which are not limited here. Preferably, the coulombic efficiency of the carbon material is 48% to 55%.

[0090] Secondly, this application provides a negative electrode material, the negative electrode material comprising the carbon material and active substance described in the first aspect, the carbon material having pores, and at least a portion of the active substance filling the pores of the carbon material.

[0091] In some embodiments, the active material refers to a substance that can react with lithium to perform lithium insertion / extraction. Specifically, the active material includes at least one selected from Li, Na, K, Sn, Ge, Si, Fe, SiO, Mg, Ti, Zn, Al, P, and Cu; the active material can be an elemental metal.

[0092] In some embodiments, the active material can be Si particles, Sn particles, Ge particles, or Al particles. In other embodiments, the active material can be a silicon-lithium alloy, a silicon-magnesium alloy, etc. Of course, it should be noted that in some cases, the active material includes elemental particles and alloys.

[0093] The negative electrode material provided in this application includes a carbon material with pores, mainly micropores. Silicon-based active particles fill the pores of the carbon material, which helps to improve the compaction density and energy density of the negative electrode material. At the same time, the silicon-based active particles can be uniformly distributed in the pores of the carbon material, which helps to improve the uniformity of the expansion tension distribution during the cycling process of the negative electrode material, reduce the splitting and breakage of the negative electrode material, and reduce the safety hazards of the negative electrode material.

[0094] In some embodiments, the carbon content in the negative electrode material is 70% to 98% by mass, specifically 70%, 75%, 80%, 85%, 90%, 92%, 95%, 96%, 97%, or 98%, etc. Of course, other values ​​within the above range are also possible, and are not limited here.

[0095] In some embodiments, the active material includes silicon-based active particles.

[0096] In some embodiments, the silicon-based active particles include at least one of amorphous silicon, crystalline silicon, silicon oxide, silicon alloy, and a composite of crystalline and amorphous silicon.

[0097] In some embodiments, the median particle size of the silicon-based active particles is 0.85 nm to 2.45 nm, specifically 0.85 nm, 0.9 nm, 0.95 nm, 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, 2.0 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, or 2.45 nm, etc. Of course, other values ​​within the above range are also possible, and are not limited here.

[0098] In some embodiments, the specific surface area of ​​the negative electrode material is 0.5 m². 2 / g~5m 2 / g, specifically 0.5m 2 / g、1m 2 / g, 1.5m 2 / g、2m 2 / g, 2.5m 2 / g、3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.5m 2 / g or 5m 2 / g, etc., can also be other values ​​within the above range, and are not limited here.

[0099] In some embodiments, the pore volume of the negative electrode material is 0.001 cm³. 3 / g~0.020cm 3 / g, specifically 0.001cm 3 / g, 0.005cm 3 / g, 0.01cm 3 / g, 0.015cm 3 / g or 0.02cm 3 / g, etc., can also be other values ​​within the above range, and are not limited here.

[0100] In some embodiments, the compaction density of the negative electrode material is 0.90 g / cm³.3 ~1.10g / cm 3 Specifically, it could be 0.9 g / cm³. 3 0.92g / cm 3 0.95g / cm 3 0.98g / cm 3 1g / cm 3 Or 1.1g / cm 3 "etc." can also be other values ​​within the above range, and no restrictions are imposed here.

[0101] Thirdly, this application provides a method for preparing a carbon material, such as... Figure 2 As shown, it includes the following steps:

[0102] Step S10: The mixed solution containing inorganic zinc salt and polymer monomer is subjected to in-situ polymerization and co-precipitation reaction to obtain a complex containing polymer and zinc hydroxide, wherein the concentration of the inorganic zinc salt is 0.045 mol / L to 0.400 mol / L.

[0103] Step S20: The composite is dried to form a precursor containing the polymer and zinc oxide;

[0104] In step S30, the precursor is subjected to step-heating heat treatment in an inert gas atmosphere to obtain a carbon material with a rod-shaped structure, wherein the aspect ratio of the carbon material is 3 to 15.

[0105] The carbon material preparation method provided in this application involves in-situ polymerization of a mixed solution containing inorganic zinc salt and polymer monomers. During the in-situ polymerization process, the inorganic zinc salt in the solution precipitates to form zinc hydroxide, while the polymer monomers polymerize to form a polymer. The polymer and zinc hydroxide co-precipitate, generating a composite containing both polymer and zinc hydroxide. Furthermore, the aspect ratio of the carbon material is controlled by adjusting the concentration of the inorganic zinc salt in the mixed solution, thereby controlling the carbon material to have a rod-like structure. The composite is then dried. During the drying process, the zinc hydroxide decomposes to form zinc oxide with a rod-like structure, while the polymer particles stack up using the zinc oxide as a template. A precursor containing polymer and zinc oxide is formed into a rod-shaped structure. The precursor is subjected to step-by-step heat treatment in an inert gas atmosphere. During the heat treatment, the structure of the rod-shaped precursor can be initially solidified, reducing the possibility of damage to the rod-shaped structure due to excessively rapid heating. Then, carbonization treatment is carried out at a higher temperature. During the high-temperature carbonization process, the polymer in the precursor decomposes to form a carbon material containing zinc oxide. Then, the zinc oxide is partially reduced to elemental zinc by the carbon in the carbon material. Finally, the zinc vapor is released from the interior of the carbon material at high temperature. The zinc vapor can act as a pore-forming agent to form uniform pores in the carbon material. The pores extend from the interior of the carbon material to the surface of the carbon material, thereby forming a porous rod-shaped carbon material.

[0106] The preparation method of this application is described in detail below with reference to the embodiments:

[0107] Step S10: The mixed solution containing inorganic zinc salt and polymer monomer is subjected to in-situ polymerization to obtain a complex containing polymer and zinc hydroxide, wherein the concentration of the inorganic zinc salt is 0.045 mol / L to 0.400 mol / L.

[0108] In step S10, the concentration of the inorganic zinc salt can be 0.045 mol / L, 0.048 mol / L, 0.05 mol / L, 0.10 mol / L, 0.20 mol / L, 0.24 mol / L, 0.30 mol / L, 0.35 mol / L, or 0.40 mol / L, but is not limited to the listed values; other values ​​within this range are also applicable. When the concentration of the inorganic zinc salt in the mixed solution is too high, the longitudinal growth of the rod-shaped zinc oxide structure begins to be inhibited by the shear force generated by stirring, the lateral growth of zinc oxide becomes dominant, the aspect ratio decreases, and the particles begin to agglomerate, leading to the disappearance of the rod-shaped structure, thus preventing the formation of rod-shaped carbon materials. Controlling the concentration of the inorganic zinc salt in the mixed solution within the above-mentioned range is beneficial for controlling the aspect ratio of the carbon material and for the formation of rod-shaped structures in the carbon material.

[0109] In some embodiments, the inorganic zinc salt includes at least one of zinc chloride, zinc nitrate, zinc acetate, zinc sulfate, zinc fluorosilicate, zinc fluoroborate, and zinc gluconate. It is understood that during the formation of carbon materials, the inorganic zinc salt can form rod-shaped zinc oxide structures, and the rod-shaped structure of zinc oxide facilitates the formation of rod-shaped structures in carbon materials.

[0110] In some embodiments, the polymer monomer includes a first monomer and a second monomer.

[0111] In some embodiments, the polymer monomer includes a first monomer, which includes phenol and its derivatives, melamine and its derivatives, or benzoic acid and its derivatives.

[0112] In some embodiments, the polymer monomer includes a first monomer, which includes at least one of phenol, resorcinol, catechol, hydroquinone, phloroglucinol, p-aminophenol, and dopamine.

[0113] In some embodiments, the polymer monomer includes a first monomer, which includes at least one of melamine, benzomelamine, trichloromelamine, and hexamethylmelamine.

[0114] In some embodiments, the polymer monomer includes a first monomer, which includes at least one of benzoic acid, p-methylbenzoic acid, p-fluorobenzoic acid, and 3-chlorobenzoic acid.

[0115] In some embodiments, the polymer monomer includes a second monomer, which includes at least one of formaldehyde, furfural, acetaldehyde, propionaldehyde, and butyraldehyde.

[0116] In some embodiments, the mixed solution further includes a surfactant, the surfactant comprising at least one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium carboxymethyl cellulose, and polyvinylpyrrolidone.

[0117] Understandably, adding surfactants to the mixed solution can enhance the adsorption of zinc hydroxide on polymer particles and improve the co-precipitation efficiency of polymer and zinc hydroxide.

[0118] In some embodiments, the mixed solution further includes a surfactant, the concentration of which is 0.10 mol / L to 0.15 mol / L, specifically 0.1 mol / L, 0.11 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L, or 0.15 mol / L, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0119] In some embodiments, the mixed solution further includes a pH adjuster, which includes at least one of ammonia, sodium hydroxide, and potassium hydroxide.

[0120] In some embodiments, the pH value of the mixed solution is 10 to 14, specifically 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5 or 14, etc., and is not limited here.

[0121] In some embodiments, the reaction temperature of the in-situ polymerization reaction is 28°C to 50°C, specifically 28°C, 30°C, 35°C, 40°C, 43°C, 45°C, 46°C, 48°C or 50°C, etc., which are not limited here.

[0122] In some embodiments, the reaction time of the in-situ polymerization is 4h to 12h, specifically 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h or 12h, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0123] In some embodiments, the in-situ polymerization reaction is carried out under stirring, with the stirring rate controlled at 100 r / min to 1500 r / min. Specifically, it can be 100 r / min, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 800 r / min, 1000 r / min, 1200 r / min, 1300 r / min, or 1500 r / min, but it is not limited to the listed values. Other values ​​within this range are also applicable.

[0124] In some embodiments, the specific steps of performing an in-situ polymerization reaction on a mixed solution containing inorganic zinc salt and polymer monomer to obtain a composite containing polymer and zinc hydroxide are as follows:

[0125] The polymer monomer, inorganic zinc salt, surfactant and ammonia are added to a solvent and mixed to obtain a mixed solution containing inorganic zinc salt and polymer monomer;

[0126] The mixed solution was subjected to in-situ polymerization and co-precipitation reactions, followed by solid-liquid separation to obtain a complex containing the polymer and zinc hydroxide.

[0127] In some embodiments, the solvent includes at least one of water, ethanol, methanol, and propanol.

[0128] In some embodiments, the solid-liquid separation includes at least one of filtration separation or centrifugal separation.

[0129] Step S20: The composite is dried to form a precursor containing the polymer and zinc oxide.

[0130] In some embodiments, the drying temperature is 60℃ to 90℃, specifically 60℃, 65℃, 70℃, 75℃, 80℃, 85℃ or 90℃, etc., and of course, other values ​​within the above range are also possible, which are not limited here.

[0131] In some embodiments, the drying time is 6h to 24h, specifically 6h, 8h, 10h, 12h, 15h, 18h, 20h or 24h, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0132] In step S30, the precursor is subjected to step-heating heat treatment in an inert gas atmosphere to obtain a carbon material with a rod-shaped structure, wherein the aspect ratio of the carbon material is 3 to 15.

[0133] In some embodiments, the stepped heating heat treatment includes: placing the precursor at 300℃~400℃ for 1h~3h, then heating it to 600℃~900℃ for 1h~6h, and finally heating it to 950℃~1100℃ for 3h~6h.

[0134] Specifically, by heat-treating the precursor at 300℃~400℃, the structure of the rod-shaped precursor can be initially solidified, reducing the possibility of damage to the rod-shaped structure due to excessively rapid heating. During heat treatment at 600℃~900℃, the polymer in the precursor undergoes carbonization and pyrolysis to form rod-shaped carbon materials containing zinc oxide. Then, before heating to 950℃~1100℃, the zinc oxide is partially reduced to elemental zinc by the carbon in the carbon material. Finally, during the heat treatment stage at 950℃~1100℃, gasification and dezincification occur, and elemental zinc is extracted from the interior of the carbon material, forming pores that extend from the interior to the surface, thereby forming a rod-shaped carbon material with a large number of micropores.

[0135] In some embodiments, the heating rate of the stepped heating heat treatment is 1℃ / min to 5℃ / min, specifically 1℃ / min, 1.5℃ / min, 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min or 5℃ / min, etc., and is not limited here.

[0136] In some embodiments, the inert gas atmosphere includes at least one of helium, nitrogen, and argon.

[0137] In some embodiments, the method further includes cooling, shaping, and sieving the product after stepped heating heat treatment, wherein the shaping includes at least one of mechanical crushing, grinding, ball milling, or air jet milling.

[0138] Fourthly, this application provides a battery comprising the carbon material described in the first aspect or the carbon material prepared by the method described in the third aspect.

[0139] Example

[0140] Example 1

[0141] (1) Mix 950 mL of ethanol and 400 mL of water to form a mixed solvent. Add 10 g of resorcinol, 60 g of cetyltrimethylammonium bromide (CTAB) and 5 mL of ammonia water to the mixed solvent in sequence. Stir at 30 °C for 0.5 h to mix it evenly. Then, add 15 mL of formaldehyde and 40 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.0484 mol / L) to obtain a mixed solution containing resorcinol, formaldehyde and saturated zinc acetate (pH is 12.4).

[0142] (2) The mixed solution (pH 12.4) was stirred at 30°C for 24 h, and the stirring rate was controlled at 1000 r / min. The mixture was then separated by filtration to obtain a complex containing resorcinol formaldehyde resin and zinc hydroxide.

[0143] (3) The complex containing resorcinol formaldehyde resin and zinc hydroxide was vacuum dried at 60°C for 12 h to form a precursor containing resorcinol formaldehyde resin and zinc oxide.

[0144] (4) The precursor containing resorcinol formaldehyde resin and zinc oxide is placed in a carbonization furnace, nitrogen is introduced, and the temperature is raised to 350℃ at 1.5℃ / min for 2 hours. Then the temperature is raised to 600℃ at 1.5℃ / min for 2 hours. Finally, the temperature is raised to 950℃ at 1.5℃ / min for 4 hours. After cooling, grinding and sieving, a carbon material with a rod-shaped structure is obtained.

[0145] The carbon material prepared in this embodiment has a rod-like structure and is porous. The length, diameter, total pore volume, specific surface area, average pore diameter, median particle size, and the volume ratio of micropores, mesopores, and macropores in the total pore volume of the carbon material are detailed in Table 1.

[0146] Figure 3 Here is a scanning electron microscope image of the carbon material prepared in this embodiment, as shown below. Figure 3 As shown, the carbon material has a rod-like structure.

[0147] The carbon materials were tested using a Phytochemical iPore 620 pore size analyzer and the BET pore size distribution method. The pore size distribution data of the carbon materials were obtained through DFT simulation analysis using the nitrogen isotherm adsorption characteristic curve. Figure 7 The pore size distribution test diagram of the carbon material prepared in this embodiment is shown below. Figure 7 As shown, the pore structure of carbon materials includes micropores smaller than 2 nm.

[0148] Example 2

[0149] Unlike Example 1, in step (1), 80 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.0969 mol / L) was added, and the rest of the operation was the same as in Example 1.

[0150] The carbon material prepared in this embodiment has a rod-like structure and is porous. The length, diameter, total pore volume, specific surface area, average pore diameter, median particle size, and the volume ratio of micropores, mesopores, and macropores in the total pore volume of the carbon material are detailed in Table 1.

[0151] Figure 4 Here is a scanning electron microscope image of the carbon material prepared in this embodiment, as shown below. Figure 4As shown, the carbon material has a rod-like structure. Because the microporous structure is beyond the resolution of a scanning electron microscope, the microporous structure on the carbon material is difficult to observe.

[0152] The carbon materials were tested using a Phytochemical iPore 620 pore size analyzer and the BET pore size distribution method. The pore size distribution data of the carbon materials were obtained through DFT simulation analysis using the nitrogen isotherm adsorption characteristic curve. Figure 8 The image shows the pore size distribution of the carbon material obtained in this embodiment. Figure 8 As shown, the pore structure of carbon materials is mainly composed of micropores smaller than 2 nm.

[0153] Example 3

[0154] Unlike Example 1, in step (1), 120 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.1452 mol / L) was added, and the rest of the operation was the same as in Example 1.

[0155] The carbon material prepared in this embodiment has a rod-like structure and is porous. The length, diameter, total pore volume, specific surface area, average pore diameter, median particle size, and the volume ratio of micropores, mesopores, and macropores in the total pore volume of the carbon material are detailed in Table 1.

[0156] Example 4

[0157] Unlike Example 1, in step (1), 160 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.1936 mol / L) was added, and the rest of the operation was the same as in Example 1.

[0158] The carbon material prepared in this embodiment has a rod-like structure and is porous. The length, diameter, total pore volume, specific surface area, average pore diameter, median particle size, and the volume ratio of micropores, mesopores, and macropores in the total pore volume of the carbon material are detailed in Table 1.

[0159] Example 5

[0160] Unlike Example 1, in step (1), 200 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.2420 mol / L) was added, and the rest of the operation was the same as in Example 1.

[0161] The carbon material prepared in this embodiment has a rod-like structure and is porous. The length, diameter, total pore volume, specific surface area, average pore diameter, median particle size, and the volume ratio of micropores, mesopores, and macropores in the total pore volume of the carbon material are detailed in Table 1.

[0162] Example 6

[0163] Unlike Example 1, in step (1), 240 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.2904 mol / L) was added, and the rest of the operation was the same as in Example 1.

[0164] The carbon material prepared in this embodiment has a rod-like structure and is porous. The length, diameter, total pore volume, specific surface area, average pore diameter, median particle size, and the volume ratio of micropores, mesopores, and macropores in the total pore volume of the carbon material are detailed in Table 1.

[0165] Example 7

[0166] Unlike Example 1, in step (1), 280 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.3388 mol / L) was added, and the rest of the operation was the same as in Example 1.

[0167] The carbon material prepared in this embodiment has a rod-like structure and is porous. The length, diameter, total pore volume, specific surface area, average pore diameter, median particle size, and the volume ratio of micropores, mesopores, and macropores in the total pore volume of the carbon material are detailed in Table 1.

[0168] Example 8

[0169] Unlike Example 1, in step (1), 320 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.3872 mol / L) was added, and the rest of the operation was the same as in Example 1.

[0170] The carbon material prepared in this embodiment has a rod-like structure and is porous. The length, diameter, total pore volume, specific surface area, average pore diameter, median particle size, and the volume ratio of micropores, mesopores, and macropores in the total pore volume of the carbon material are detailed in Table 1.

[0171] Comparative Example 1

[0172] Unlike Example 1, in step (1), 360 mL of saturated zinc acetate solution at 25 °C (the concentration of the reaction system is 0.4425 mol / L) was added, and the rest of the operation was the same as in Example 1.

[0173] Comparative Example 2

[0174] (1) Mix 950 mL of ethanol and 400 mL of water to form a mixed solvent. Add 10 g of resorcinol, 60 g of cetyltrimethylammonium bromide (CTAB) and 5 mL of ammonia water to the mixed solvent in sequence. Stir at 30 °C for 0.5 h to mix it evenly. Then, add 15 mL of formaldehyde and 40 mL of tetraethyl silicate to obtain a mixed solution containing resorcinol, formaldehyde and tetraethyl silicate (pH 12.6).

[0175] (2) The mixed solution (pH 12.6) was stirred at 30°C for 24 hours and then separated by filtration to obtain a complex of resorcinol-formaldehyde resin and silica.

[0176] (3) The composite was vacuum dried at 60°C for 12 h to form a precursor containing resorcinol formaldehyde resin and silica.

[0177] (4) The precursor was placed in a carbonization furnace, nitrogen was introduced, and the temperature was increased to 350℃ at 1.5℃ / min for 2 hours. Then the temperature was increased to 600℃ at 1.5℃ / min for 2 hours. Finally, the temperature was increased to 950℃ at 1.5℃ / min for 4 hours. After cooling, grinding and sieving, carbonized product powder with spherical structure was obtained.

[0178] (5) The spherical carbonized product powder was etched in hydrofluoric acid, and then filtered, washed and dried to obtain carbon material with a spherical structure.

[0179] Test methods

[0180] (1) Method for testing the aspect ratio of carbon materials:

[0181] Carbon materials were photographed using a Hitachi S-4800 scanning electron microscope from Japan. 200 carbon material particles were randomly selected from the images and measured to obtain the length and diameter of each particle. The aspect ratio of each particle was calculated based on the length and diameter, and then the average aspect ratio of the 200 particles was calculated.

[0182] (2) Method for testing the pore size distribution of carbon materials:

[0183] Carbon materials were tested using the iPore620 pore size analyzer and the BET pore size distribution test method. The pore size distribution data of carbon materials were obtained by DFT simulation analysis using the isothermal adsorption characteristic curve of nitrogen gas. The average pore size, total pore volume, BET specific surface area, and the volume ratio of micropores, mesopores and macropores in the total pore volume of carbon materials were then obtained.

[0184] (3) Test method for the mass content of oxygen in carbon materials:

[0185] Using the German Fold Oxygen Nitrogen Hydrogen Analyzer ONH 2000, carbon material was coated with flux and then melted in a graphite crucible under an inert atmosphere. The oxygen-containing elements in the carbon material were reduced to carbon dioxide by the carbon in the graphite crucible. The generated carbon dioxide was then introduced into an infrared detector along with a carrier gas. The oxygen content was quantitatively calculated by statistically analyzing the changes in the infrared signal of the carbon dioxide.

[0186] (4) Electrochemical performance testing:

[0187] The carbon materials, conductive carbon black (super P) and binder (LA133) obtained in Examples 1-8 and Comparative Examples 1-2 were mixed in a ratio of 91:3:6 to form a slurry and uniformly coated onto copper foil. After drying, the slurry was prepared into electrode sheets, assembled into coin cells, and tested for their charging capacity and coulombic efficiency on the Blue Battery Test Cabinet M340A.

[0188] The test results are detailed in Tables 1 and 2.

[0189] Table 1 Performance parameters of carbon materials in each embodiment and comparative example.

[0190]

[0191] Table 2. Electrochemical performance test results of carbon materials prepared in each embodiment and comparative example.

[0192]

[0193]

[0194] As shown in Table 1, during the preparation of carbon materials in Examples 1-8 and Comparative Example 1, as the concentration of zinc acetate in the reaction system continuously increased, the longitudinal growth of the generated rod-shaped zinc oxide template became dominant, and the aspect ratio of the synthesized rod-shaped carbon materials continuously increased. However, in Examples 7, 8, and Comparative Example 1, as the concentration of zinc acetate in the reaction system excessively increased, the longitudinal growth of the rod-shaped zinc oxide began to be inhibited by the shear force generated by stirring, and its transverse growth became dominant. The aspect ratio began to continuously decrease, and when the amount of saturated zinc acetate used reached 360 mL in Comparative Example 1, the particles agglomerated, and the rod-shaped structure disappeared. In this process, as the concentration of zinc acetate in the reaction system increases, more pores are formed in the carbon material, and the total pore volume increases. However, the increase in the concentration of zinc acetate in the reaction system also intensifies the pore-forming effect, causing some micropores in the carbon material to collapse and merge, reducing the proportion of micropores and increasing the average pore size of the carbon material. As the concentration of zinc acetate in the reaction system increases excessively, the zinc distribution in the carbon material becomes uneven, some zinc agglomerates, the pore-forming ability weakens, and the total pore volume of the carbon material begins to decrease, the proportion of micropores increases, and the average pore size of the carbon material also begins to decrease. Therefore, the rod-shaped carbon materials formed in Examples 1-8 and Comparative Example 1 show a trend of first gradually increasing and then gradually decreasing in terms of average pore size, specific surface area, total pore volume, and proportion of macropore volume, while the proportion of micropores shows the opposite trend of first gradually decreasing and then gradually increasing.

[0195] As can be seen from Tables 1 and 2, during the preparation of the carbon materials in Examples 1 to 8, as the concentration of zinc acetate in the reaction system increases, zinc acetate decomposes upon heating to produce zinc oxide. The zinc oxide is reduced by the carbon material, and oxygen is transferred to the carbon material, resulting in an increase in both the mass content of oxygen and the zinc content in the carbon material. The pore-forming effect of zinc increases, more pores are formed in the carbon material, the total pore volume increases, the ability of the carbon material to intercalate lithium increases, and its charging capacity also increases accordingly. A small amount of oxygen doping in the carbon material can also provide lone pairs of electrons, which interact with the π electrons in the carbon material to form a conjugated system, thereby improving the conductivity of the carbon material.

[0196] Based on the test data from Examples 7 and 1, it is known that a higher zinc acetate concentration in the reaction system leads to a higher oxygen content in the carbon material, resulting in an increased charging capacity. However, the higher oxygen content may decrease the continuity of C=C in the carbon material, causing the conjugated system to break down and reducing conductivity. When the carbon material is used in the anode material, the amount of active lithium ions consumed during cycling increases, leading to a decrease in the initial coulombic efficiency of the carbon material compared to Example 1. Therefore, considering both the initial coulombic efficiency and charging capacity of the carbon material, the preferred oxygen content in the carbon material is 1% to 4.2%.

[0197] Figure 5 Here is a scanning electron microscope image of the carbon material provided in Comparative Example 1 of this application, as shown. Figure 5 As shown, the particles in the carbon material agglomerate, and the rod-like structure disappears; Figure 9 The pore size distribution diagram of the carbon material provided in Comparative Example 1 of this application is as follows: Figure 9 As shown, carbon materials contain only micropores and mesopores, and no macropores.

[0198] In the preparation of the carbon material in Comparative Example 1, due to the excessively high concentration of zinc acetate in the reaction system, the longitudinal growth of rod-shaped zinc oxide began to be inhibited by the shear force generated by stirring. The lateral growth of zinc oxide became dominant, the aspect ratio decreased, and the particles began to agglomerate, resulting in the disappearance of the rod-shaped structure. Thus, the carbon material with a rod-shaped structure could not be formed.

[0199] According to the test data of Example 1 and Comparative Example 1, in Comparative Example 1, the zinc acetate concentration in the reaction system was too high. During the stepped heating heat treatment, the carbon material was oxidized and etched by zinc oxide, and the zinc oxide was reduced by the carbon material. Oxygen was transferred to the carbon material, resulting in excessively high oxygen and zinc content in the carbon material. The increase in oxygen content disrupted the continuity of C=C in the material, causing the conjugated system to break down. This led to a significant decrease in the conductivity of the carbon material, the formation of more pores in the carbon material, and an increase in the amount of active lithium ions consumed during the cycling process of the negative electrode material after the carbon material was used. This resulted in a decrease in the coulombic efficiency of the carbon material. At the same time, the proportion of mesopores and macropores in the carbon material also increased significantly, leading to a decrease in the structural stability of the carbon material. The particles were easily broken when the electrode was pressed by rollers, and the side reactions between the carbon material and the electrolyte were intensified, causing the continuous formation of the SEI interface film, which further reduced the coulombic efficiency of the carbon material.

[0200] Figure 6 Here is a scanning electron microscope image of the carbon material provided in Comparative Example 2 of this application, as shown. Figure 6 As shown, the particles in the carbon material agglomerate to form spherical carbon materials; Figure 10 The pore size distribution diagram of the carbon material provided in Comparative Example 2 of this application is shown below. Figure 10 As shown, the proportion of mesopores and macropores in carbon materials increases significantly, and the pores in carbon materials are mainly mesopores and macropores.

[0201] According to the test data of Examples 3, 4 and Comparative Example 2, the carbon material prepared in Comparative Example 2 has similar average pore size, specific surface area and total pore volume to the carbon materials prepared in Examples 3 and 4. However, since inorganic zinc salt was replaced with tetraethyl silicate in the preparation process of the carbon material in Comparative Example 2, the resulting carbon material is spherical porous carbon. The carbon material has a high proportion of mesopores and macropores and fewer micropores. The carbon material particles have large gaps and weakened mechanical properties. This causes some particles of the spherical porous carbon to break when the electrode is pressed by rollers, which increases the specific surface area of ​​the carbon material and intensifies the side reactions with the electrolyte. This leads to a further increase in the thickness of the SEI film, resulting in a decrease in the charging capacity of the carbon material and a significant reduction in its coulombic efficiency.

[0202] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A carbon material, characterized in that, The carbon material has a rod-like structure, is porous, has an aspect ratio of 3.2 to 14.7, a length of 1.02 μm to 5 μm, a diameter of 0.2 μm to 3 μm, and a total pore volume of 0.2 cm³. 3 / g~0.8cm 3 / g, the pores in the carbon material include micropores, and the volume of the micropores accounts for 80% to 95% of the total pore volume.

2. The carbon material according to claim 1, characterized in that, It meets at least one of the following technical features: (1) The specific surface area of ​​the carbon material is 500 m². 2 / g~1600m 2 / g; (2) The average pore size of the pores in the carbon material is 0.8 nm to 2.5 nm; (3) The pores in the carbon material include mesopores, and the volume of the mesopores accounts for 5% to 15% of the total pore volume; (4) The pores in the carbon material include macropores, and the volume of the macropores accounts for 0% to 5% of the total pore volume; (5) The carbon material contains oxygen, and the mass content of oxygen in the carbon material is 1% to 5.5%; (6) The charging capacity of the battery assembled from the carbon material is 250mAh / g to 400mAh / g; (7) The coulombic efficiency of the battery assembled from the carbon material is 40% to 55%.

3. A negative electrode material, characterized in that, The negative electrode material includes the carbon material and active substance as described in claim 1 or 2, wherein the carbon material has pores, and at least a portion of the active substance fills the pores of the carbon material.

4. The negative electrode material according to claim 3, characterized in that, It meets at least one of the following technical features: (1) The carbon content in the negative electrode material is 70% to 98% by mass; (2) The active material includes silicon-based active particles; (3) The active material includes silicon-based active particles, which include at least one of amorphous silicon, crystalline silicon, silicon oxide, silicon alloy, and a composite of crystalline silicon and amorphous silicon; (4) The active material includes silicon-based active particles, wherein the median particle size of the silicon-based active particles is 0.85 nm to 2.45 nm; (5) The specific surface area of ​​the negative electrode material is 0.5 m². 2 / g~5m 2 / g; (6) The pore volume of the negative electrode material is 0.001 cm³. 3 / g~0.020cm 3 / g; (7) The compaction density of the negative electrode material is 0.90 g / cm³. 3 ~1.1g / cm 3 .

5. A method for preparing a carbon material, characterized in that, Includes the following steps: An in-situ polymerization and co-precipitation reaction is carried out on a mixed solution containing inorganic zinc salt and polymer monomer to obtain a complex containing polymer and zinc hydroxide, wherein the concentration of the inorganic zinc salt is 0.045 mol / L to 0.400 mol / L. The composite is dried to form a precursor containing the polymer and zinc oxide. The precursor is subjected to step-heating heat treatment in an inert gas atmosphere to obtain a carbon material with a rod-shaped structure, wherein the aspect ratio of the carbon material is 3.2 to 14.

7.

6. The preparation method according to claim 5, characterized in that, It meets at least one of the following technical features: (1) The inorganic zinc salt includes at least one of zinc chloride, zinc nitrate, zinc acetate, zinc sulfate, zinc fluorosilicate, zinc fluoroborate and zinc gluconate; (2) The polymer monomer includes a first monomer and a second monomer; (3) The polymer monomer includes a first monomer, which includes phenol and its derivatives, melamine and its derivatives or benzoic acid and its derivatives; (4) The polymer monomer includes a first monomer, which includes at least one of phenol, resorcinol, catechol, hydroquinone, phloroglucinol, p-aminophenol and dopamine; (5) The polymer monomer includes a first monomer, which includes at least one of melamine, benzomelamine, trichloromelamine and hexamethylmelamine; (6) The polymer monomer includes a first monomer, which includes at least one of benzoic acid, p-methylbenzoic acid, p-fluorobenzoic acid and 3-chlorobenzoic acid; (7) The polymer monomer includes a second monomer, which includes at least one of formaldehyde, furfural, acetaldehyde, propionaldehyde and butyraldehyde; (8) The mixed solution also includes a surfactant, which includes at least one of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium carboxymethyl cellulose, and polyvinylpyrrolidone; (9) The mixed solution also includes a surfactant, the concentration of which is 0.10 mol / L to 0.15 mol / L; (10) The mixed solution also includes a pH adjuster, which includes at least one of ammonia, sodium hydroxide and potassium hydroxide; (11) The pH value of the mixed solution is 10 to 14; (12) The reaction temperature of the in-situ polymerization reaction is 28℃~50℃; (13) The reaction time for the in-situ polymerization is 4h to 12h; (14) The in-situ polymerization reaction is carried out under stirring, and the stirring rate is controlled at 100 r / min to 1500 r / min.

7. The preparation method according to claim 5 or 6, characterized in that, The specific steps for carrying out in-situ polymerization and co-precipitation reactions of a mixed solution containing inorganic zinc salt and polymer monomer to obtain a complex containing polymer and zinc hydroxide are as follows: The polymer monomer, inorganic zinc salt, surfactant and ammonia are added to a solvent and mixed to obtain a mixed solution containing inorganic zinc salt and polymer monomer; The mixed solution was subjected to in-situ polymerization and co-precipitation reactions, followed by solid-liquid separation to obtain a complex containing the polymer and zinc hydroxide.

8. The preparation method according to claim 7, characterized in that, It meets at least one of the following technical features: (1) The solvent includes at least one of water, ethanol, methanol and propanol; (2) The solid-liquid separation includes at least one of filtration separation or centrifugal separation.

9. The preparation method according to claim 5, characterized in that, It meets at least one of the following technical features: (1) The drying temperature is 60℃~90℃; (2) The drying process takes 6 hours to 24 hours; (3) The stepped heating heat treatment includes: placing the precursor at 300℃~400℃ for 1h~3h, then heating it to 600℃~900℃ for 1h~6h, and finally heating it to 950℃~1100℃ for 3h~6h. (4) The heating rate of the stepped heating heat treatment is 1℃ / min to 5℃ / min; (5) The inert gas atmosphere includes at least one of helium, nitrogen, and argon; (6) The method further includes cooling, shaping and sieving the product after the stepped heating heat treatment, wherein the shaping includes at least one of mechanical crushing, grinding, ball milling or air jet milling.

10. A battery, characterized in that, The battery comprises the carbon material according to any one of claims 1 to 2 or the carbon material prepared by the method according to any one of claims 5 to 9.

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