Biomass-based hard carbon material with high sodium storage platform capacity and preparation method and application thereof

Abstract

The application belongs to the technical field of sodium ion battery materials, and discloses a biomass-based high-sodium storage platform capacity hard carbon material and a preparation method and application thereof.The preparation method comprises the following steps: firstly, the biomass precursor is subjected to acid washing and impurity removal to remove inorganic ash and retain a natural porous skeleton; then, pre-oxidation treatment is performed in an air atmosphere to construct a cross-linked network rich in carbonyl groups; finally, two-step high-temperature carbonization is performed in an inert atmosphere, and cooling is performed to obtain the product.The application successfully induces edge densification of carbon microcrystals through the regulation of "pre-oxidation cross-linking and solidification + two-step carbonization", and constructs a large number of nano-porous networks.The material maintains high initial coulombic efficiency, greatly improves the sodium storage capacity in the low potential platform area, has excellent high-rate fast-charging safety and long cycle stability, and has a capacity retention rate of 94.18% after 300 cycles, and has wide industrial application prospects.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, specifically relating to a biomass-based high sodium storage platform capacity hard carbon material and its preparation method and application. Background Technology

[0002] With societal development, the demand for energy storage is constantly growing. The environmental pollution and energy shortages caused by the overexploitation of fossil fuels are forcing the development of clean and sustainable new energy technologies. Among numerous new energy technologies, lithium-ion batteries, due to their high energy density, long cycle life, environmental friendliness, flexibility, and convenience, have been widely used in new energy vehicles, portable electronic products, aerospace, and other fields. However, lithium resources face the problems of scarcity and uneven distribution. Against this backdrop, sodium resources, which are abundant, widely distributed, and inexpensive in the Earth's crust, have come into researchers' view. More importantly, sodium belongs to the same group as lithium in the periodic table, sharing similar physicochemical properties and electrochemical reaction mechanisms. In the field of energy storage, sodium-ion batteries possess a similar "rocking chair" charge-discharge mechanism to lithium-ion batteries, and are expected to become an excellent alternative to lithium-ion batteries in the future.

[0003] However, graphite, which performs exceptionally well in the lithium-ion battery field, has a sodium storage capacity of only 12 mAhg in sodium-ion batteries. -1 This significantly hinders its application in sodium-ion batteries. Research indicates that the main reason for graphite's low sodium storage capacity is the thermodynamic instability between sodium ions and graphite, making it difficult to form stable Na-C binary intercalation compounds. Therefore, to realize the commercial application of sodium-ion batteries, it is urgent to find suitable anode materials. Currently, reported sodium-ion battery anode materials can be mainly divided into metallic materials, alloy materials, carbon-based materials, and organic materials. However, most of these materials are not only costly but also have complex preparation processes, contradicting the low-cost advantage of sodium-ion batteries and thus deviating from practical applications. Considering cost-effectiveness, hard carbon among carbon-based materials is considered the most commercially promising anode material for sodium-ion batteries due to its wide availability, low cost, and simple preparation process.

[0004] The sodium storage capacity of hard carbon mainly consists of a high-potential ramp region (defect adsorption) and a low-potential plateau region (micropore / closed-pore filling). However, during the direct high-temperature carbonization of traditional biomass feedstocks, the lack of effective crystal and pore network structure constraints leads to disordered collapse during carbonization. This causes many of the sodium-storing micropores formed inside to evolve into large-diameter open pores or even close and disappear at high temperatures, resulting in a low capacity in the low-potential plateau region, which determines the overall energy density. Furthermore, an excessively large specific surface area can trigger severe side reactions, reducing the initial coulombic efficiency.

[0005] Patent CN 116692858 A discloses a method for preparing a biomass hard carbon anode material for sodium-ion batteries, including treating cellulose with strong alkali hydrothermal stirring, pre-oxidation, and then high-temperature carbonization to obtain the hard carbon material. However, this material has poor reversible capacity. Furthermore, for natural biomass materials such as bamboo powder, wood powder, and coconut shells, which are composed of cellulose, hemicellulose, and lignin, high-temperature strong alkali treatment can excessively dissolve the hemicellulose and lignin, leading to the destruction of the natural structure of the biomass.

[0006] Patent CN 120943235 A discloses a method for preparing a high-capacity bamboo-based hard carbon anode material, which includes impregnating the low-temperature carbonized bamboo powder obtained by oxidizing and carbonizing bamboo powder at low temperature with a metal salt solution, followed by high-temperature carbonization to obtain a metal-doped layered bamboo-based hard carbon material. However, this material has poor reversible capacity and a complex preparation process, which is not conducive to industrial application.

[0007] Therefore, how to construct a large number of chemically stable nanoporous networks within the hard carbon phase while maintaining a low specific surface area is a bottleneck mechanism that urgently needs to be solved to improve the capacity of biomass hard carbon sodium storage platforms. Summary of the Invention

[0008] To overcome the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing biomass-based hard carbon materials with high sodium storage capacity. This method employs an optimized strategy of introducing oxygen functional groups through air pre-oxidation to promote precursor cross-linking, followed by a two-step carbonization process to construct a bamboo-based hard carbon anode material with a microporous internal structure and a dense outer edge. This significantly improves the sodium storage capacity in the low-potential plateau region of sodium-ion batteries while maintaining the initial coulombic efficiency.

[0009] Another objective of this invention is to provide a biomass-based hard carbon material with a high sodium storage platform capacity.

[0010] Another object of the present invention is to provide the application of the above-mentioned biomass-based high sodium storage platform capacity hard carbon material in the anode of sodium-ion batteries.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] A method for preparing a biomass-based high sodium storage platform capacity hard carbon material includes the following steps:

[0013] (1) The biomass precursor is pretreated by acid leaching to obtain acid-leached biomass powder;

[0014] (2) The acid-leached biomass powder is pre-oxidized to obtain pre-oxidized biomass powder;

[0015] (3) Under an inert atmosphere, the pre-oxidized biomass powder is subjected to high-temperature carbonization treatment, cooled and ground to obtain biomass-based high sodium storage platform capacity hard carbon material.

[0016] Preferably, in step (1), the acid leaching pretreatment is as follows: the biomass precursor is soaked in an acid solution, stirred and washed until neutral, dried and then ground.

[0017] Preferably, in step (1), the acid solution is an HCl solution; the concentration of the acid solution is 0.5-1.5M, and the stirring time is 4-8h.

[0018] Preferably, in step (1), the biomass precursor is bamboo powder, coconut shell or wood powder.

[0019] Preferably, in step (2), the pre-oxidation is carried out in an air atmosphere, the pre-oxidation temperature is 200-300℃, the heating rate is 1-3℃ / min, and the holding time is 4-8h.

[0020] Preferably, in step (3), the inert atmosphere is argon or nitrogen.

[0021] Preferably, in step (3), the high-temperature carbonization treatment is a stepped high-temperature carbonization, specifically: heating to 300-500℃ at a rate of 1-3℃ / min, holding for 1-3h, then heating to 1200-1400℃ at a rate of 1-3℃ / min, holding for 2-4h, then cooling down at 4-6℃ / min, and then naturally cooling to room temperature.

[0022] Preferably, in step (3), the cooling is reduced to 600~1000℃.

[0023] A biomass-based high sodium storage platform capacity hard carbon material is prepared by the above method.

[0024] Preferably, the biomass-based high sodium storage platform capacity hard carbon material contains micropores with dense outer edges, and the pore size is mostly 1-3 nm, 0.025 cm. 3 / g≤pore volume≤0.050 cm³ 3 / g, 0.3nm < interlayer spacing < 0.4nm, 15 m 2 / g≤Specific Surface Area≤30 m² 2 / g.

[0025] The above-mentioned biomass-based high sodium storage platform capacity hard carbon material is used in sodium-ion battery anode materials.

[0026] The present invention has the following advantages and beneficial effects compared with the prior art:

[0027] (1) This invention uses low-cost bamboo powder as a precursor and employs a mild hydrochloric acid washing process, which not only precisely removes inorganic ash and metallic impurities from natural biomass bamboo powder, but also avoids the collapse of the natural microstructure of biomass caused by other acid processes such as sulfuric acid and strong alkali high-temperature pretreatment. This provides a solid three-dimensional framework for the subsequent construction of nanopores within the material. The process is simple, green, and environmentally friendly, and is suitable for large-scale industrial production.

[0028] (2) Existing technologies often employ a single-step high-temperature carbonization method followed by air pre-oxidation. The intense thermal shock can easily lead to the collapse of the porous network or the formation of numerous ineffective open pores. This invention cleverly combines air pre-oxidation with a two-step high-temperature carbonization process: First, pre-oxidation at a specific temperature range (200~300℃) promotes precursor esterification and cross-linking, introducing a large amount of C=O. Then, in the first low-temperature pre-carbonization stage (e.g., 300~500℃), the cross-linked network undergoes dehydration rearrangement and full solidification under mild conditions, avoiding skeletal damage caused by intense gas release. Finally, in the second high-temperature pyrolysis stage, oxygen-containing functional groups react to generate gases such as CO and CO2, which escape and etch the dense cross-linked network. Simultaneously, the carbon skeleton encloses at high temperatures, generating numerous nanopores in situ, providing thermodynamic conditions for sodium clusters during sodium storage. This significantly increases the sodium storage capacity of the material in the plateau region below 0.1V. Furthermore, the densified skeleton significantly reduces side reactions of the electrolyte on the material surface and SEI film growth. Therefore, the material of the present invention maintains excellent first coulomb efficiency while achieving high platform capacity. Attached Figure Description

[0029] Figure 1 The images are XRD patterns (a) and fitted data (b) of Examples 1-4, with a scanning speed of 5° / min and a scanning range of 10-90°.

[0030] Figure 2 The N2 adsorption-desorption curves (a) and pore size distribution diagrams (b) obtained based on the DFT model for Examples 1-4 are shown. The degassing temperature was 300℃ and the degassing time was 8h.

[0031] Figure 3 The graphs are a comparison of the first-cycle charge-discharge curves (a) and a platform slope capacity bar chart (b) for Examples 1-4.

[0032] Figure 4 This is a comparison chart of the rate performance of Examples 1-4.

[0033] Figure 5 This is a comparison chart of the cycle performance of Examples 1-4.

[0034] Figure 6 This is a charge-discharge curve of Comparative Example 1.

[0035] Figure 7 This is a charge-discharge curve of Comparative Example 2. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings. However, the implementation of the present invention is not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0037] The bamboo powder has a particle size of 200 mesh.

[0038] Example 1

[0039] Acid leaching pretreatment: Bamboo powder is placed in 1M HCl solution and stirred at room temperature for 6 hours. After filtration, it is washed with deionized water until neutral (pH=7). It is then dried and ground in a forced-air drying oven at 90℃ to obtain acid-leached bamboo powder.

[0040] High-temperature carbonization: Acid-impregnated bamboo powder is placed in a tube furnace with an argon atmosphere. The temperature is increased to 400℃ at a rate of 2℃ / min and held for 2 hours. The temperature is then increased to 1300℃ at a rate of 2℃ / min and held for 3 hours. The temperature is then decreased to 800℃ at a rate of 5℃ / min and allowed to cool naturally to room temperature. After grinding, a hard carbon material is obtained, named TBHC-1300.

[0041] Example 2

[0042] Acid leaching pretreatment: Bamboo powder is placed in 1M HCl solution and stirred at room temperature for 6 hours. After filtration, it is washed with deionized water until neutral (pH=7). It is then dried and ground in a forced-air drying oven at 90℃ to obtain acid-leached bamboo powder.

[0043] Air pre-oxidation: Acid-soaked bamboo powder is placed in a muffle furnace and heated to 250°C at a heating rate of 2°C / min in air atmosphere, held at that temperature for 4 hours, and then cooled to room temperature to obtain pre-oxidized bamboo powder.

[0044] High-temperature carbonization: Pre-oxidized bamboo powder is placed in a tube furnace with an argon atmosphere. The temperature is increased to 400℃ at a rate of 2℃ / min and held for 2 hours. The temperature is then increased to 1300℃ at a rate of 2℃ / min and held for 3 hours. The temperature is then decreased to 800℃ at a rate of 5℃ / min and allowed to cool naturally to room temperature. After grinding, a hard carbon material is obtained, named TO-250-4-BHC.

[0045] Example 3

[0046] Acid leaching pretreatment: Bamboo powder is placed in 1M HCl solution and stirred at room temperature for 6 hours. After filtration, it is washed with deionized water until the center (pH=7). It is then dried and ground in a forced-air drying oven at 90℃ to obtain acid-leached bamboo powder.

[0047] Air pre-oxidation: Acid-soaked bamboo powder is placed in a muffle furnace and heated to 250°C at a heating rate of 2°C / min in air atmosphere, held at that temperature for 6 hours, and then cooled to room temperature to obtain pre-oxidized bamboo powder.

[0048] High-temperature carbonization: Pre-oxidized bamboo powder is placed in a tube furnace with an argon atmosphere. The temperature is increased to 400℃ at a rate of 2℃ / min and held for 2 hours. The temperature is then increased to 1300℃ at a rate of 2℃ / min and held for 3 hours. The temperature is then decreased to 800℃ at a rate of 5℃ / min and allowed to cool naturally to room temperature. After grinding, a hard carbon material is obtained, named TO-250-6-BHC.

[0049] Example 4

[0050] Acid leaching pretreatment: Bamboo powder is placed in 1M HCl solution and stirred at room temperature for 6 hours. After filtration, it is washed with deionized water until the center (pH=7). It is then dried and ground in a forced-air drying oven at 90℃ to obtain acid-leached bamboo powder.

[0051] Air pre-oxidation: Acid-soaked bamboo powder is placed in a muffle furnace and heated to 250°C at a heating rate of 2°C / min under air atmosphere. The temperature is maintained for 8 hours and then cooled to room temperature to obtain pre-oxidized bamboo powder.

[0052] High-temperature carbonization: Pre-oxidized bamboo powder is placed in a tube furnace with an argon atmosphere. The temperature is increased to 400℃ at a rate of 2℃ / min and held for 2 hours. The temperature is then increased to 1300℃ at a rate of 2℃ / min and held for 3 hours. The temperature is then decreased to 800℃ at a rate of 5℃ / min and allowed to cool naturally to room temperature. After grinding, a hard carbon material is obtained, named TO-250-8-BHC.

[0053] Comparative Example 1

[0054] Acid leaching pretreatment: Bamboo powder is placed in 1M HCl solution and stirred at room temperature for 6 hours. After filtration, it is washed with deionized water until neutral (pH=7). It is then dried and ground in a forced-air drying oven at 90℃ to obtain acid-leached bamboo powder.

[0055] Air pre-oxidation: Acid-soaked bamboo powder is placed in a muffle furnace and heated to 300°C at a heating rate of 2°C / min under air atmosphere. The temperature is maintained for 6 hours and then cooled to room temperature to obtain pre-oxidized bamboo powder.

[0056] High-temperature carbonization: Pre-oxidized bamboo powder is placed in a tube furnace with an argon atmosphere. The temperature is increased to 400℃ at a rate of 2℃ / min and held for 2 hours. The temperature is then increased to 1300℃ at a rate of 2℃ / min and held for 3 hours. The temperature is then decreased to 800℃ at a rate of 5℃ / min and allowed to cool naturally to room temperature. After grinding, a hard carbon material is obtained, named TO-300-6-BHC.

[0057] Comparative Example 2

[0058] Acid leaching pretreatment: Bamboo powder is placed in 1M HCl solution and stirred at room temperature for 6 hours. After filtration, it is washed with deionized water until neutral (pH=7). It is then dried and ground in a forced-air drying oven at 90℃ to obtain acid-leached bamboo powder.

[0059] High-temperature carbonization: Acid-impregnated bamboo powder is placed in a tube furnace with an argon atmosphere. The temperature is increased to 1300℃ at a rate of 2℃ / min and held for 3 hours. The temperature is then decreased to 800℃ at a rate of 5℃ / min and allowed to cool naturally to room temperature. After grinding, a hard carbon material is obtained, named TBHC-1300-D.

[0060] The hard carbon materials prepared in Examples 1-4 were subjected to XRD and BET tests.

[0061] Figure 1 The XRD comparison spectra of the hard carbon materials prepared in Examples 1-4 show that, compared to Example 1, the (002) diffraction peak of the pre-oxidized samples in Examples 2-4 shifted to the left. Further, according to the Bragg equation... The interlayer spacing histogram was obtained by fitting the (002) diffraction peak. It can be seen that the interlayer spacing of the sample increased after pre-oxidation treatment and increased with the extension of the heat preservation time. This is because pre-oxidation promotes the esterification and cross-linking of the precursor, increases the content of oxygen functional groups, and hinders the stacking of carbon layers in the subsequent carbonization process, resulting in the expansion of the interlayer spacing.

[0062] Figure 2 The N2 adsorption-desorption curves and pore size distributions obtained based on the DFT model are shown for the hard carbon materials prepared in Examples 1-4. It can be seen that the N2 adsorption-desorption curves of the hard carbon materials exhibit a typical type IV adsorption isotherm shape, with an H4 type hysteresis loop. Specific surface area and pore volume data are shown in Table 1.

[0063] Table 1: Specific surface area and pore volume data for Examples 1-4

[0064]

[0065] As shown in Table 1, compared to Example 1, the specific surface area and pore volume of Examples 2-4 after pre-oxidation treatment increased, and increased with the extension of pre-oxidation time. Furthermore, according to... Figure 2 In (b) of the example, the pores in Example 1 are mostly mesopores of 5-7 nm, while the pores in Examples 2-4 are mostly micropores of 1-3 nm. This further illustrates that the number of micropores inside the material is greatly increased after pre-oxidation. This is because pre-oxidation introduces a large number of oxygen functional groups, which escape as CO and CO2 gases during the subsequent carbonization process to etch the carbon skeleton. At the same time, the carbon layer surrounds the material at high temperature, generating a large number of micropores in situ, which is beneficial to the improvement of the platform capacity.

[0066] The hard carbon materials prepared in Examples 1-4 were applied to sodium-ion battery anode materials, and the specific steps are as follows:

[0067] Weigh the hard carbon material, conductive carbon black Super C65, and sodium carboxymethyl cellulose (CMC) prepared in Examples 1-4 according to a mass ratio of 8:1:1. Grind and mix them, then add 1.75g ​​of deionized water. Stir the mixture in a degassing machine to obtain a uniform slurry. Coat the slurry onto a copper foil current collector with a coating thickness of 150µm. After vacuum drying for 12h, cut out circular electrode sheets with a diameter of 12mm.

[0068] The circular electrode was transferred to an argon-atmospheric glove box for coin cell assembly. The battery case was a CR2025 coin cell, and the electrolyte was NP-035 (1M NaPF6 in DME=100 Vol%). Electrochemical performance was tested on a LAND system.

[0069] Figure 3 The figures show the capacity-voltage curves and ramp-plateau capacity graphs of the hard carbon materials prepared in Examples 1-4 at 0.1C. At 0.1C, the reversible capacity and initial coulombic efficiency of Example 1 are 315.49 mAh g⁻¹. -1 And 84.50%; the reversible capacities of Examples 2-4 after pre-oxidation treatment were 313.79 mAh g, respectively. -1 350.05 mAh g -1 320.71 mAh g -1 The initial coulombic efficiencies were 84.7%, 84.75%, and 83.35%, respectively. Pre-oxidation increases the interlayer spacing and the number of micropores, which is beneficial for the transport and storage of sodium ions. The sample obtained after 6 hours of pre-oxidation exhibited the best reversible capacity, increasing the reversible capacity by 34.56 mAh g while maintaining the initial coulombic efficiency. -1 The ramp capacity and platform capacity data are shown in Table 2.

[0070] Table 2: Slope and platform capacity data for Examples 1-4

[0071]

[0072] The sodium storage mechanism of hard carbon is a three-stage mechanism of "adsorption-intercalation-pore filling". The increased interlayer spacing and micropore number caused by pre-oxidation are conducive to intercalation sodium storage and pore filling sodium storage, resulting in improved sodium storage capacity in the plateau region below 0.1V. In addition, the oxygen functional groups and a small number of large open pores remaining during carbonization can act as active sites for sodium storage in the slope region. As shown in Table 2, under the synergistic effect of the two mechanisms, the sample pre-oxidized for 6 hours showed improved slope and plateau capacities, exhibiting the best electrochemical performance.

[0073] Figure 4 The graphs show the rate performance of the hard carbon materials prepared in Examples 1-4 at different current densities. It can be seen that, overall, the sample that has undergone pre-oxidation treatment for 6 hours can also exhibit high capacity under high current and has the best rate performance.

[0074] Figure 5 The graph shows the cycling performance of the hard carbon materials prepared in Examples 1-4 at 0.5C. It can be seen that the sample pre-oxidized for 6 hours exhibits a cycling performance of 341.18 mAh g⁻¹ at 0.5C. -1 The reversible capacity remains at 321.31 mAh g after 300 cycles. -1 It has a capacity retention rate of 94.18% and exhibits excellent cycle performance.

[0075] Figure 6 The image shows the first charge-discharge curve of Comparative Example 1 at 0.1C. It can be seen that when the pre-oxidation temperature is increased to 300℃, the biomass precursor begins to carbonize, the material undergoes catalytic cracking, and the pre-oxidation esterification crosslinking mechanism fails. The final hard carbon material exhibits significantly lower performance compared to the control sample without pre-oxidation treatment, with a performance of only 187.27 mAhg at 0.1C. -1 It has reversible capacity and a first coulomb efficiency of 69.84%.

[0076] Figure 7 The image shows the first charge-discharge curves of Comparative Example 2 at 0.1C. It can be seen that when using the one-step carbonization method, because the precursor does not undergo gentle dehydration and rearrangement or slow gas release, the violent gas release during the heating process to 1300℃ will negatively impact the carbon framework rearrangement and graphite crystallite stacking, thus affecting performance. Ultimately, the hard carbon material obtained by the one-step carbonization method has a performance of only 267.88 mAh g⁻¹ at 0.1C. -1 It has reversible capacity and a first coulomb efficiency of 79.45%.

[0077] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a biomass-based high sodium storage platform capacity hard carbon material, characterized in that, Includes the following steps: (1) The biomass precursor is pretreated by acid leaching to obtain acid-leached biomass powder; (2) The acid-leached biomass powder is pre-oxidized to obtain pre-oxidized biomass powder; (3) Under an inert atmosphere, the pre-oxidized biomass powder is subjected to high-temperature carbonization treatment and then cooled to obtain biomass-based high sodium storage platform capacity hard carbon material.

2. The method for preparing biomass-based high sodium storage platform capacity hard carbon material according to claim 1, characterized in that, In step (1), the acid leaching pretreatment is as follows: the biomass precursor is soaked in an acid solution, stirred and washed until neutral, dried and then ground.

3. The method for preparing biomass-based high sodium storage platform capacity hard carbon material according to claim 2, characterized in that, In step (1), the acid solution is an HCl solution; the concentration of the acid solution is 0.5-1.5M, and the stirring time is 4-8h.

4. The method for preparing biomass-based high sodium storage platform capacity hard carbon material according to claim 3, characterized in that, In step (1), the biomass precursor is bamboo powder, coconut shell or wood powder.

5. The method for preparing biomass-based high sodium storage platform capacity hard carbon material according to claim 1, characterized in that, In step (2), the pre-oxidation is carried out in an air atmosphere, the pre-oxidation temperature is 200-300℃, the heating rate is 1-3℃ / min, and the holding time is 4-8h.

6. The method for preparing biomass-based high sodium storage platform capacity hard carbon material according to claim 1, characterized in that, In step (3), the inert atmosphere is argon or nitrogen.

7. The method for preparing biomass-based high sodium storage platform capacity hard carbon material according to claim 1, characterized in that, In step (3), the high-temperature carbonization treatment is a stepped high-temperature carbonization, specifically: the temperature is increased to 300-500℃ at a rate of 1-3℃ / min, and held for 1-3h, then increased to 1200-1400℃ at a rate of 1-3℃ / min, and held for 2-4h, then cooled down at a rate of 4-6℃ / min, and then naturally cooled to room temperature.

8. A biomass-based high sodium storage capacity hard carbon material, characterized in that, It is prepared by the method described in any one of claims 1 to 7.

9. The biomass-based high sodium storage platform capacity hard carbon material according to claim 8, characterized in that, The biomass-based high sodium storage platform capacity hard carbon material contains micropores and has a dense outer edge, with a layer spacing of 0.3 nm < interlayer spacing < 0.4 nm.

10. The application of the biomass-based high sodium storage platform capacity hard carbon material as described in claim 8 or 9 in sodium-ion battery anode materials.

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