Hard carbon negative electrode material, preparation method thereof and sodium ion battery

Abstract

The application provides a hard carbon negative electrode material and a preparation method thereof and a sodium ion battery, and relates to the technical field of sodium ion batteries; the preparation method of the hard carbon negative electrode material comprises the following steps: mixing plastic, biomass material and coal material to obtain a composite carbon source; mixing polyvinyl halide with the composite carbon source to obtain a mixed raw material; heating the mixed raw material to 300-500 DEG C and keeping the temperature for 1-3 hours to obtain an intermediate product; heating the intermediate product to 1200-1500 DEG C and keeping the temperature for 3-5 hours to obtain the hard carbon negative electrode material; the application takes plastic, biomass material and coal material as raw materials, and improves the sodium storage capacity of the negative electrode material and the initial efficiency under the premise of ensuring the compaction density through composite sintering; and through the introduction of polyvinyl halide, the raw material conversion rate can be improved, and the ash can be removed in the sintering process; compared with traditional acid pickling and iron removal, the wastewater discharge amount can be greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and in particular to a hard carbon anode material, its preparation method, and a sodium-ion battery. Background Technology

[0002] Lithium-ion batteries have been widely used in energy storage systems due to their advantages such as high power density and long cycle life. However, with the development of energy storage materials, the uneven distribution and scarcity of lithium resources have limited the large-scale application of lithium-ion batteries. Meanwhile, sodium metal shares similar physical and chemical properties with lithium metal, and its resources are widely distributed and inexpensive, making sodium-ion batteries an important alternative to lithium-ion batteries.

[0003] The anode material of sodium-ion batteries is a key factor determining the performance of sodium-ion batteries. Therefore, researching and developing anode materials with excellent electrochemical performance is crucial for the development of sodium-ion batteries.

[0004] Currently, the anode materials for sodium-ion batteries are mainly hard carbon materials; among them, coal-based materials, as organic matter with high carbon content, can be used as raw materials to prepare hard carbon anode materials on a large scale.

[0005] Coal-based hard carbon anode materials prepared from coal-based materials have high compaction density, but they have the drawback of low sodium storage capacity, which cannot meet the performance requirements of sodium-ion batteries.

[0006] Therefore, how to improve the sodium storage capacity of coal-based hard carbon anode materials is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] To address the issue of low sodium storage capacity in existing coal-based hard carbon anode materials, this invention provides a method for preparing hard carbon anode materials. This method uses plastics, biomass materials, and coal-based materials as raw materials, and obtains a hard carbon anode material with a core-shell structure through composite sintering. While ensuring compaction density, this method improves the sodium storage capacity of the anode material and enhances the initial efficiency, thus solving the problem of low sodium storage capacity in existing coal-based hard carbon anode materials.

[0008] The technical solution adopted by this invention to solve its technical problem is:

[0009] A method for preparing a hard carbon anode material includes the following steps:

[0010] S1: Mix plastics, biomass materials and coal-based materials to obtain a composite carbon source;

[0011] S2: Mix poly(ethylene halide) with the composite carbon source to obtain a mixed raw material;

[0012] S3: Under an inert gas atmosphere, the mixed raw materials are heated to 300-500°C and held at that temperature for 1-3 hours to obtain an intermediate product;

[0013] S4: Under an inert gas atmosphere, the intermediate product is heated to 1200-1500℃ and held for 3-5 hours to obtain a hard carbon anode material.

[0014] Optionally, the plastic is a waste plastic product.

[0015] Optionally, the plastic is selected from at least one of phenolic resin, polyurethane, polyethylene, polypropylene, polyvinyl chloride, polystyrene, and acrylonitrile-butadiene-styrene copolymer.

[0016] Optionally, the biomass material is low-ash biomass waste.

[0017] Optionally, the low-ash biomass waste is selected from at least one of sugarcane bagasse, cottonseed hulls, and fruit shells.

[0018] Optionally, the coal material is selected from at least one of anthracite, bituminous coal, coking coal, and pitch coke.

[0019] Optionally, the polyhalogenated ethylene is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride.

[0020] Optionally, in step S1, the mass ratio of the plastic, the biomass material, and the coal material is (0.5-2.5):(0.5-2.5):1; and in step S2, the mass ratio of the composite carbon source to the polyhalogenated ethylene is (25-50):1.

[0021] Another object of the present invention is to provide a hard carbon anode material, which is prepared by the preparation method of hard carbon anode material as described above.

[0022] Another object of the present invention is to provide a sodium-ion battery comprising the hard carbon anode material as described above.

[0023] The beneficial effects of this invention are:

[0024] The method for preparing hard carbon anode material provided by this invention uses plastic, biomass and coal as raw materials. Through composite sintering, the sodium storage capacity of the anode material is improved and the initial efficiency is improved while ensuring the compaction density. Furthermore, by introducing polyhalogenated ethylene, not only can the raw material conversion rate be improved, but ash can also be removed during the sintering process. Compared with traditional acid washing to remove iron, it can greatly reduce the amount of wastewater discharged. Detailed Implementation

[0025] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting 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.

[0026] To address the problem of low sodium storage capacity in existing coal-based hard carbon anode materials, this invention provides a method for preparing a hard carbon anode material, which includes the following steps:

[0027] S1: Mix plastics, biomass materials and coal-based materials to obtain a composite carbon source;

[0028] S2: Mix poly(ethylene halide) with a composite carbon source to obtain a mixed raw material;

[0029] S3: Under an inert gas atmosphere, the mixed raw materials are heated to 300-500℃ and held for 1-3 hours to obtain the intermediate product;

[0030] S4: Under an inert gas atmosphere, the intermediate product is heated to 1200-1500℃ and held for 3-5 hours to obtain hard carbon anode material.

[0031] To ensure the uniformity and stability of the electrochemical performance of the negative electrode material, this invention preferably uses plastic, biomass material, and coal material with a particle size of 5-8 μm. Specifically, step S1 is preferably performed as follows: according to the formula, the plastic, biomass material, and coal material are pulverized to 5-8 μm and mixed evenly to obtain a composite carbon source. To ensure sufficient reaction, this invention preferably uses polyhalogenated polyethylene with a particle size of 1-3 μm. Specifically, step S2 is preferably performed as follows: the polyhalogenated polyethylene is pulverized to 1-3 μm, and according to the formula, the polyhalogenated polyethylene is mixed with the composite carbon source to obtain a mixed raw material. To facilitate temperature control, this invention preferably uses steps S3 and S4 to raise the temperature at a rate of 1-3 °C / min.

[0032] Specifically, step S3 of the present invention is preferably carried out as follows: under an inert gas atmosphere, the mixed raw materials are added to a reaction vessel, rotary kiln or fluidized bed and heated to 300℃-500℃ at a rate of 1-3℃ / min, and kept at the temperature for 1-3 hours to obtain an intermediate product.

[0033] The preferred step S4 of this invention is carried out as follows: using a pusher furnace or roller furnace, under an inert gas atmosphere, the intermediate product is heated to 1200-1500℃ for 3-5 hours at a rate of 1-3℃ / min, then crushed and sieved to obtain a hard carbon anode material.

[0034] In this invention, the inert gas in steps S3 and S4 is preferably nitrogen.

[0035] Due to the large aromatic molecular structure of coal-based materials, the hard carbon materials prepared from them have small lattice spacing and large lamellar sizes, which is detrimental to improving sodium storage capacity and rate performance. Therefore, this invention introduces plastics, biomass materials, and coal-based materials as a composite carbon source. During the sintering process of this composite carbon source, firstly, the plastics and biomass materials generate hard carbon that coats the surface of the coal-based material, forming a core-shell structure. This, while ensuring compaction density, helps improve the sodium storage capacity of the anode material and enhances the initial efficiency. Secondly, through the composite sintering of plastics, biomass materials, and coal-based materials, the sodium storage capacity of the anode material can be improved. The process of co-thermal conversion of biomass materials and coal-based materials allows for the adjustment of the lattice spacing and lamellar size of hard carbon materials, thereby improving the sodium storage capacity of hard carbon anode materials. Furthermore, biomass materials can introduce trace elements such as potassium, sodium, calcium, and silicon to activate the carbon skeleton during heat treatment, thus endowing hard carbon anode materials with a rich pore structure and improving their sodium storage capacity, which is beneficial for improving electrochemical performance during charge and discharge. Moreover, the special microstructure generated by biomass materials during growth helps to introduce closed-pore structures into hard carbon materials, further enhancing the sodium storage capacity of hard carbon anode materials.

[0036] Furthermore, to ensure the electrochemical performance of the anode material, the current preparation process of coal-based hard carbon anode materials typically requires acid washing to remove iron. This process is not only cumbersome but also generates a large amount of wastewater. To address this issue, this invention introduces poly(ethylene halide) into the preparation process. On one hand, poly(ethylene halide) decomposes during heating, producing hydrogen halides. Hydrogen halides help promote the conversion of more raw materials into amorphous carbon during thermal decomposition, reducing the generation of volatile organic compounds and improving the raw material conversion rate. On the other hand, halogens can react with metal ions in the raw materials to form salts with lower boiling points and can also react with silicates in the raw materials. They can volatilize during heating, effectively reducing the ash content in the anode material, thereby avoiding acid washing during preparation, simplifying the preparation process, and reducing wastewater discharge.

[0037] The method for preparing hard carbon anode material provided by this invention uses plastic, biomass and coal as raw materials. Through composite sintering, the sodium storage capacity of the anode material is improved and the initial efficiency is improved while ensuring the compaction density. Furthermore, by introducing polyhalogenated ethylene, not only can the raw material conversion rate be improved, but ash can also be removed during the sintering process. Compared with traditional acid washing to remove iron, it can greatly reduce the amount of wastewater discharged.

[0038] To further reduce costs, the plastic used in this invention is preferably recycled plastic.

[0039] Furthermore, the plastic of the present invention is preferably selected from at least one of phenolic resin (Bakelite), polyurethane, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS).

[0040] The preferred biomass material of this invention is low-ash biomass waste, and more preferably, the low-ash biomass waste is selected from at least one of sugarcane bagasse, cottonseed hulls, and fruit shells.

[0041] The preferred coal material of this invention is selected from at least one of anthracite, bituminous coal, coking coal, and pitch coke; the preferred polyhalogenated ethylene is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride. Specifically, during the heating process, the hydrogen chloride and hydrogen fluoride released from the polyhalogenated ethylene promote the conversion of more amorphous carbon during the thermal decomposition of the raw materials, reducing the generation of volatile organic compounds and improving the conversion rate; chlorine reacts with metal ions in the raw materials to form salts with lower boiling points, and fluorine reacts with silicates in the raw materials, which can volatilize during the heating process, effectively reducing the ash content of the finished product. Compared with traditional acid washing for iron removal, 30 tons of wastewater are reduced per ton of product.

[0042] To balance the electrochemical performance and economic efficiency of hard carbon anode materials, the preferred mass ratio of plastic, biomass material, and coal-based material in step S1 is (0.5-2.5):(0.5-2.5):1; and the preferred mass ratio of composite carbon source to polyhalogenated polyethylene in step S2 is (25-50):1. The preparation method of hard carbon anode materials provided by this invention utilizes widely available and readily available raw materials, is low-cost, and environmentally friendly. Specifically, the cost of the hard carbon anode material provided by this invention is no more than US$3,000 per ton, far lower than that of traditional hard carbon materials; and compared with the traditional acid washing and iron removal process, it can reduce wastewater discharge by 30 tons per ton of product.

[0043] Another object of the present invention is to provide a hard carbon anode material, which is prepared by the preparation method of hard carbon anode material as described above.

[0044] The hard carbon anode material provided by this invention uses plastic, biomass and coal as raw materials in its preparation process. Through composite sintering, the sodium storage capacity of the anode material is improved and the initial efficiency is improved while ensuring the compaction density. Furthermore, by introducing polyhalogenated polyethylene, not only can the raw material conversion rate be improved, but ash can also be removed during the sintering process. Compared with traditional acid washing to remove iron, it can greatly reduce the amount of wastewater discharged.

[0045] Another object of the present invention is to provide a sodium-ion battery comprising the hard carbon anode material as described above.

[0046] The sodium-ion battery provided by this invention uses plastic, biomass, and coal as raw materials in the preparation of hard carbon anode material. Through composite sintering, the sodium storage capacity of the anode material is improved and the initial efficiency is improved while ensuring the compaction density. Furthermore, by introducing polyhalogenated polyethylene, not only can the raw material conversion rate be improved, but ash can also be removed during the sintering process. Compared with traditional acid washing to remove iron, this can greatly reduce the amount of wastewater discharged.

[0047] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0048] Example 1

[0049] This embodiment provides a method for preparing a hard carbon anode material, including the following steps:

[0050] S1: Waste bakelite, bagasse and anthracite are crushed to 6μm and mixed evenly in a mass ratio of 2:1:1 to obtain a composite carbon source;

[0051] S2: After pulverizing polytetrafluoroethylene to 2μm, it is mixed with composite carbon source at a mass ratio of 1:40 to obtain mixed raw material;

[0052] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 400℃ at 2℃ / min, and the temperature is maintained for 2 hours to obtain the intermediate product;

[0053] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1400℃ at 2℃ / min in a pusher furnace, held at that temperature for 4 hours, pulverized, and sieved to obtain hard carbon anode material.

[0054] Example 2

[0055] This embodiment provides a method for preparing a hard carbon anode material, including the following steps:

[0056] S1: Waste bakelite, bagasse, and anthracite are crushed to 6μm and mixed evenly in a mass ratio of 0.5:0.5:1 to obtain a composite carbon source;

[0057] S2: After pulverizing polytetrafluoroethylene to 2μm, it is mixed with composite carbon source at a mass ratio of 1:40 to obtain mixed raw material;

[0058] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 400℃ at 2℃ / min, and the temperature is maintained for 2 hours to obtain the intermediate product;

[0059] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1400℃ at 2℃ / min in a pusher furnace, held at that temperature for 4 hours, pulverized, and sieved to obtain hard carbon anode material.

[0060] Example 3

[0061] This embodiment provides a method for preparing a hard carbon anode material, including the following steps:

[0062] S1: Waste bakelite, bagasse, and anthracite are crushed to 6μm and mixed evenly in a mass ratio of 2.5:2.5:1 to obtain a composite carbon source;

[0063] S2: After pulverizing polytetrafluoroethylene to 2μm, it is mixed with composite carbon source at a mass ratio of 1:40 to obtain mixed raw material;

[0064] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 400℃ at 2℃ / min, and the temperature is maintained for 2 hours to obtain the intermediate product;

[0065] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1400℃ at 2℃ / min in a pusher furnace, held at that temperature for 4 hours, pulverized, and sieved to obtain hard carbon anode material.

[0066] Example 4

[0067] This embodiment provides a method for preparing a hard carbon anode material, including the following steps:

[0068] S1: Waste polyurethane, cottonseed hulls and coking coal are crushed to 5μm respectively, and mixed evenly in a mass ratio of 0.5:2.5:1 to obtain a composite carbon source;

[0069] S2: After pulverizing polyvinylidene fluoride to 1μm, it is mixed with the composite carbon source at a mass ratio of 1:50 to obtain a mixed raw material;

[0070] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 300℃ at 2℃ / min, and the temperature is maintained for 3 hours to obtain the intermediate product;

[0071] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1200℃ at 2℃ / min in a pusher furnace, held at that temperature for 5 hours, pulverized, and sieved to obtain hard carbon anode material.

[0072] Example 5

[0073] This embodiment provides a method for preparing a hard carbon anode material, including the following steps:

[0074] S1: Waste polystyrene, cottonseed hulls and anthracite are crushed to 8μm and mixed evenly in a mass ratio of 2.5:0.5:1 to obtain a composite carbon source;

[0075] S2: After pulverizing polyvinyl chloride to 3μm, it is mixed evenly with the composite carbon source at a mass ratio of 1:25 to obtain a mixed raw material;

[0076] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 500℃ at 2℃ / min, and the temperature is maintained for 1 hour to obtain the intermediate product;

[0077] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1500℃ at 2℃ / min in a pusher furnace, held at that temperature for 3 hours, pulverized, and sieved to obtain hard carbon anode material.

[0078] Comparative Example 1

[0079] This comparative example provides a method for preparing a hard carbon anode material, including the following steps:

[0080] S1: The anthracite coal is crushed to 6μm to obtain a carbon source;

[0081] S2: After pulverizing polytetrafluoroethylene to 2μm, it is mixed with carbon source at a mass ratio of 1:40 to obtain mixed raw materials;

[0082] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 400℃ at 2℃ / min, and the temperature is maintained for 2 hours to obtain the intermediate product;

[0083] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1400℃ at 2℃ / min in a pusher furnace, held at that temperature for 4 hours, pulverized, and sieved to obtain hard carbon anode material.

[0084] Comparative Example 2

[0085] This comparative example provides a method for preparing a hard carbon anode material, including the following steps:

[0086] S1: Pulverize waste bakelite and sugarcane bagasse to 6μm, and mix them evenly at a mass ratio of 2:1 to obtain a composite carbon source;

[0087] S2: After pulverizing polytetrafluoroethylene to 2μm, it is mixed with composite carbon source at a mass ratio of 1:40 to obtain mixed raw material;

[0088] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 400℃ at 2℃ / min, and the temperature is maintained for 2 hours to obtain the intermediate product;

[0089] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1400℃ at 2℃ / min in a pusher furnace, held at that temperature for 4 hours, pulverized, and sieved to obtain hard carbon anode material.

[0090] Comparative Example 3

[0091] This comparative example provides a method for preparing a hard carbon anode material, including the following steps:

[0092] S1: Sugarcane bagasse and anthracite are crushed to 6μm and mixed evenly at a mass ratio of 3:1 to obtain a composite carbon source;

[0093] S2: After pulverizing polytetrafluoroethylene to 2μm, it is mixed with composite carbon source at a mass ratio of 1:40 to obtain mixed raw material;

[0094] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 400℃ at 2℃ / min, and the temperature is maintained for 2 hours to obtain the intermediate product;

[0095] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1400℃ at 2℃ / min in a pusher furnace, held at that temperature for 4 hours, pulverized, and sieved to obtain hard carbon anode material.

[0096] Comparative Example 4

[0097] This comparative example provides a method for preparing a hard carbon anode material, including the following steps:

[0098] S1: Pulverize waste bakelite and anthracite to 6μm, and mix them evenly at a mass ratio of 3:1 to obtain a composite carbon source;

[0099] S2: After pulverizing polytetrafluoroethylene to 2μm, it is mixed with composite carbon source at a mass ratio of 1:40 to obtain mixed raw material;

[0100] S3: Under a nitrogen atmosphere, the mixed raw materials are added to the reactor, the temperature is increased to 400℃ at 2℃ / min, and the temperature is maintained for 2 hours to obtain the intermediate product;

[0101] S4: Under a nitrogen atmosphere, the intermediate product is heated to 1400℃ at 2℃ / min in a pusher furnace, held at that temperature for 4 hours, pulverized, and sieved to obtain hard carbon anode material.

[0102] Comparative Example 5

[0103] This comparative example provides a method for preparing a hard carbon anode material, including the following steps:

[0104] S1: Waste bakelite, bagasse and anthracite are crushed to 6μm and mixed evenly in a mass ratio of 2:1:1 to obtain a composite carbon source;

[0105] S2: Under a nitrogen atmosphere, the composite carbon source is added to the reactor, the temperature is increased to 400℃ at 2℃ / min, and the temperature is maintained for 2 hours to obtain the intermediate product;

[0106] S3: Under a nitrogen atmosphere, the intermediate product is heated to 1400℃ at 2℃ / min in a pusher furnace, held at that temperature for 4 hours, pulverized, and sieved to obtain hard carbon anode material.

[0107] The performance of the negative electrode materials prepared in the above embodiments and comparative examples was evaluated using coin cells. The electrode slurry was prepared with a ratio of active material: conductive agent SP: binder CMC: dispersant SBR = 92:3.0:1.5:3.5. Appropriate amounts of ethanol and water were added to prepare the slurry, which was then coated to a thickness of 200 μm. After drying and pressing, the slurry was formed into an electrode sheet. Using sodium metal as the counter electrode, a 1 mol / L NaPF6 DEC / EC (1:1) solution as the electrolyte, and a glass fiber filter paper membrane GF / C as the separator, a 2032 coin cell was assembled. The electrode was tested at 0.1 A g. -1 Its charge-discharge performance was tested at a current density of [value missing], and the test results are shown in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] As can be seen from the data in the table above, the preparation methods provided in each embodiment of the present invention do not require acid washing, and the prepared hard carbon anode materials all have excellent compaction density, specific capacity, and first-pass efficiency.

[0112] The difference between Comparative Example 1 and Example 1 is that only coal-based materials are used as the carbon source, and the prepared hard carbon anode material has a high compaction density, but its specific capacity and initial efficiency are both low.

[0113] The difference between Comparative Example 2 and Example 1 is that no coal-based material was added to the carbon source, resulting in a lower compaction density of the prepared hard carbon anode material.

[0114] The difference between Comparative Example 3 and Example 1 is that no plastic was added to the carbon source, and the specific capacity and first-pass efficiency of the prepared hard carbon anode material were significantly lower than those of Example 1.

[0115] The difference between Comparative Example 4 and Example 1 is that no biomass material was added to the carbon source, and the specific capacity and initial efficiency of the prepared hard carbon anode material were significantly lower than those of Example 1.

[0116] The difference between Comparative Example 5 and Example 1 is that no polyhalogenated polyethylene was added during the heating process, and the specific capacity and first efficiency of the prepared hard carbon anode material were significantly lower than those of Example 1.

[0117] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a hard carbon anode material, characterized in that, Includes the following steps: S1: Mix plastics, biomass materials and coal-based materials to obtain a composite carbon source; S2: Mix poly(ethylene halide) with the composite carbon source to obtain a mixed raw material; S3: Under an inert gas atmosphere, the mixed raw materials are heated to 300-500°C and held at that temperature for 1-3 hours to obtain an intermediate product; S4: Under an inert gas atmosphere, the intermediate product is heated to 1200-1500℃ and held for 3-5 hours to obtain a hard carbon anode material; The plastic is selected from at least one of phenolic resin, polyurethane, polyethylene, polypropylene, polyvinyl chloride, polystyrene, and acrylonitrile-butadiene-styrene copolymer.

2. The method for preparing the hard carbon anode material as described in claim 1, characterized in that, The plastic in question is a waste plastic product.

3. The method for preparing the hard carbon anode material as described in claim 1, characterized in that, The biomass material is low-ash biomass waste.

4. The method for preparing the hard carbon anode material as described in claim 3, characterized in that, Low-ash biomass waste is selected from at least one of sugarcane bagasse, cottonseed hulls, and fruit shells.

5. The method for preparing the hard carbon anode material as described in claim 1, characterized in that, The coal material is selected from at least one of anthracite, bituminous coal, coking coal, and pitch coke.

6. The method for preparing the hard carbon anode material as described in claim 1, characterized in that, The polyhalogenated ethylene is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride.

7. The method for preparing the hard carbon anode material according to any one of claims 1-6, characterized in that, In step S1, the mass ratio of the plastic, the biomass material, and the coal material is (0.5-2.5):(0.5-2.5):1; in step S2, the mass ratio of the composite carbon source to the polyhalogenated ethylene is (25-50):

1.

8. A hard carbon anode material, characterized in that, The hard carbon anode material is prepared by the method described in any one of claims 1-7.

9. A sodium-ion battery, characterized in that, Including the hard carbon anode material as described in claim 8.

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