Coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing as well as deep deliming method and application of coal-based carbon material
Through the combination of high-temperature carbonization and low-temperature alkaline washing, the problem of excessive ash content in coal-based carbon materials is solved, deep ash removal is achieved, the electrochemical and mechanical properties of the materials are improved, and it is suitable for industrial production.
Patent Information
- Application Number
- CN202510548196.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-07-18
AI Technical Summary
The prior art is difficult to meet the strict requirements of ash content in coal-based carbon materials, and conventional ash removal methods cannot achieve deep removal, which affects the electrochemical and mechanical properties of carbon materials.
The combination of high-temperature carbonization and low-temperature alkaline washing is adopted to escape most of the ash by high-temperature carbonization. Then, at low temperature, NaOH solution is used to wash and remove Al and Si substances that are difficult to remove at high temperature. The alkali solution is combined with the ash components in the coal-based carbon material to produce soluble substances, achieving deep ash deaeration.
Significantly reduce the ash content in carbon materials, improve electrochemical and mechanical properties, is suitable for industrial production, and reduces costs.
Smart Images
Figure CN120328529A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of coal-based carbon materials, and relates to a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing, and a method and application for deep ash removal thereof. Background Art
[0002] Developing carbon materials from coal is a high-value way of using coal. Compared with biomass-based carbon materials, the ash content of coal-based activated carbon is high, and the ash will also have an adverse impact on the subsequent utilization of carbon materials. For example, the ash will reduce the service life of energy storage carbon materials. Therefore, the ash removal of coal-based carbon materials is extremely important for the efficient use of coal energy.
[0003] At present, there are mainly three mainstream ash removal methods, namely physical ash removal, chemical ash removal, and physical-chemical ash removal. Physical ash removal is based on the physical property differences (such as density, magnetism, surface wettability, etc.) between organic matter and inorganic matter in coal, and realizes ash separation through methods such as gravity separation, magnetic separation, electrostatic separation, and flotation. For example, magnetic separation can remove magnetic minerals (such as magnetite) in coal, and flotation separates based on the differences in the surface properties of coal and ash particles, but the separation efficiency and ash removal efficiency are low; Chemical ash removal involves chemical reactions between pickling (such as HCl, H2SO4) or alkali washing (such as NaOH) and inorganic minerals in coal to generate soluble salts, thereby dissolving the ash. This method has the advantages of high ash removal efficiency and simple operation, but the ash removal waste liquid pollutes the environment; The physical-chemical method combines the advantages of physical and chemical ash removal methods and has good effects in ash removal and demineralization, but there are too many limiting conditions for industrial implementation, and most methods are still in the laboratory research stage.
[0004] Many industries have put forward strict requirements for the ash content in carbon materials. For example, the national standard (GBT37386-2019) for activated carbon used in supercapacitors stipulates that the ash content in carbon materials should not be higher than 0.2%. Currently, the commonly used simple ash removal methods cannot meet the ash requirements. The ash content in coal is relatively high and varies depending on the origin and coal rank; During the pyrolysis carbonization and activation pore formation of coal powder, the proportion of ash precipitated with gas is relatively low, and a large amount of ash accumulates in the target coal-based carbon material. The residual ash in the carbon material will have a greater impact on the cycle stability of the carbon material, resulting in a reduced cycle life; The presence of ash will also reduce the specific capacitance of the carbon material, affecting its power and energy density.
[0005] In summary, conventional physical ash removal, chemical ash removal, and physical-chemical ash removal cannot achieve deep ash removal, resulting in an excessive ash content in the target carbon material. Summary of the Invention
[0006] The object of the present invention is to provide a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing, and a method and application for deep deashing thereof, so as to solve the technical problem that the deashing method of the existing coal-based carbon material is difficult to meet the increasingly stringent ash content requirements.
[0007] To achieve the above object, the present invention adopts the following technical solutions:
[0008] In the first aspect, the present invention provides a method for deep deashing of a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing, including the following steps:
[0009] Carbonize the coal-based carbon material to obtain a carbonized coal-based carbon material;
[0010] Mix the carbonized coal-based carbon material with an alkali solution, heat it to a first preset temperature and keep it warm, filter and wash to obtain an alkali-washed coal-based carbon material;
[0011] Dry the alkali-washed coal-based carbon material to obtain a deeply deashed coal-based carbon material.
[0012] Further, the step of carbonizing the coal-based carbon material to obtain a carbonized coal-based carbon material specifically includes:
[0013] Heat the coal-based carbon material to a second preset temperature in an inert atmosphere to make the ash in the coal-based carbon material escape into the gas phase, and obtain a carbonized coal-based carbon material.
[0014] Further, the second preset temperature is 1200 °C to 1800 °C.
[0015] Further, the alkali solution is a NaOH solution with a concentration of 1 mol / L to 5 mol / L.
[0016] Further, the mixing ratio of the alkali solution to the carbonized coal-based carbon material is 1 g:(30 - 100) mL.
[0017] Further, the first preset temperature is 60 °C to 90 °C.
[0018] Further, the heat preservation time is 1 h to 10 h.
[0019] Further, the washing process is: repeatedly wash the filtered product with deionized water until it is neutral.
[0020] In the second aspect, the present invention provides a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing, which is prepared according to the method for deep deashing of a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing described above.
[0021] Thirdly, the present invention provides an application of the coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing in the preparation of anode materials for sodium-ion batteries.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] The present invention discloses a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing, its deep deashing method and application. The carbon material is directly heated to 1200-1800 °C for carbonization, and most of the ash in the coal will decompose and gasify, realizing the removal of 80%-90% of the ash in the coal. A large amount of Al and Si substances that are not easily removed at high temperature remain; the coal-based carbon material after high-temperature carbonization is washed with a low-temperature alkali solution to remove Al and Si substances that are difficult to evaporate at high temperature. The present invention utilizes the differences and complementarities of deashing by high-temperature carbonization (not easily removing Al and Si substances) and low-temperature alkali washing (not easily removing Fe and Ca substances) to achieve deep deashing of ash. After deashing, the impurities in the carbon material are reduced, and the carbon structure is purer, which is beneficial to improving electrochemical properties (such as conductivity, specific capacity) and mechanical properties (such as strength, toughness). The process flow of the present invention is clear, suitable for industrial production, and conducive to large-scale and low-cost preparation.
[0024] Furthermore, the present invention uses NaOH solution to react with common ash components (such as SiO2, Al2O3) in the coal-based carbon material to generate soluble sodium silicate (Na2SiO3) and sodium aluminate (NaAlO2), thereby effectively removing ash. The solubility of NaOH solution in metal oxides such as Fe2O3 is weak, but it can be further removed through subsequent washing steps. Compared with strong acid deashing (such as HCl, H2SO4), NaOH deashing can avoid excessive corrosion of the carbon skeleton and retain some metal oxides (such as Fe3O4 nanoparticles) beneficial to electrochemical properties.
[0025] Furthermore, the corrosiveness of the NaOH solution of the present invention is weak. Reacting at 60-90 °C for 1-10 hours can avoid excessive etching of the carbon skeleton, thereby retaining a high specific surface area and porosity. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0027] Figure 1 It is a flow chart of a deep deashing method of a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing of the present invention;
[0028] Figure 2a Schematic diagram of the ash content remaining in the coal-based carbon material after different deashing methods in Example 1 of the present invention;
[0029] Figure 2b Schematic diagram of the Al element content remaining in the coal-based carbon material after different deashing methods in Example 1 of the present invention;
[0030] Figure 2c Schematic diagram of the Si element content remaining in the coal-based carbon material after different deashing methods in Example 1 of the present invention;
[0031] Figure 2d Schematic diagram of the Fe element content remaining in the coal-based carbon material after different deashing methods in Example 1 of the present invention;
[0032] Figure 2e Schematic diagram of the Ca element content remaining in the coal-based carbon material after different deashing methods in Example 1 of the present invention. Detailed implementation manners
[0033] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art with respect to the present invention. In case of conflict, the definition in this specification shall prevail.
[0034] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall in no way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.
[0035] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of a numerical range or percentage range shall be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.
[0036] In this article, unless otherwise specified, terms such as "comprising", "including", "containing", "having", or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A only comprises a".
[0037] In this article, for the sake of brevity, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.
[0038] The present invention will be further described in detail below with reference to the accompanying drawings:
[0039] See Figure 1 , an embodiment of the present invention discloses a deep deashing method for coal-based carbon materials based on high-temperature carbonization and low-temperature alkali washing, comprising the following steps:
[0040] Step 1, carbonize the coal-based carbon material to obtain the carbonized coal-based carbon material;
[0041] In this step, the coal-based carbon material is laid flat in a tray and heated to 1200-1800 °C in an inert atmosphere for carbonization. Most of the ash in the coal-based carbon material will decompose and gasify, escaping into the gas phase, to obtain the carbonized coal-based carbon material;
[0042] Step 2, mix the carbonized coal-based carbon material with an alkali solution, heat it to a first preset temperature and keep it warm, filter and wash to obtain the alkali-washed coal-based carbon material;
[0043] In this step, the coal-based carbon material after high-temperature carbonization is mixed with a NaOH solution with a concentration of 1-5 mol / L in a ratio of 1 g: 30-100 mL, heated to 60-90 °C and kept for 1-10 h, with continuous stirring during the process; filter and repeatedly wash the carbon material with deionized water until it is neutral to achieve deep removal of the remaining ash, and obtain the alkali-washed coal-based carbon material.
[0044] The NaOH solution reacts chemically with common ash components (such as SiO2 and Al2O3) in the coal-based carbon material to form soluble sodium silicate (Na2SiO3) and sodium aluminate (NaAlO2), thereby effectively removing ash.
[0045] For example:
[0046] Reaction of SiO2:
[0047] SiO2 + 2NaOH → Na2SiO3 + H2O
[0048] Reaction of Al2O3:
[0049] Al2O3 + 2NaOH + 3H2O → 2NaAl(OH)4
[0050] These reactions can proceed efficiently at 60-90 °C, significantly reducing the ash content.
[0051] The NaOH solution has weak solubility for metal oxides such as Fe2O3, but it can be further removed through subsequent washing steps.
[0052] The coal-based carbon material after high-temperature carbonization has a developed microporous and mesoporous structure, and these pores are the key to electrochemical energy storage. The corrosiveness of the NaOH solution is weak. Reacting for 1 to 10 hours at 60-90 °C can avoid over-etching the carbon skeleton, thereby retaining a high specific surface area and porosity.
[0053] In addition, the NaOH deashing waste liquid contains high concentrations of sodium silicate and sodium aluminate, and the silicon-aluminum resources can be recovered by neutralization precipitation (such as adding CaCl2), or used to prepare high-value-added products such as water glass and molecular sieves. In addition, the NaOH solution can be recycled to reduce the reagent cost.
[0054] Step 3, drying the alkali-washed coal-based carbon material to obtain a deeply deashed coal-based carbon material.
[0055] The carbon material is directly heated to 1200-1800 °C for carbonization. Most of the ash in the coal will decompose and gasify, achieving the removal of 80%-90% of the ash in the coal. Substances such as Al and Si that are difficult to remove at high temperatures will remain in large amounts; the coal-based carbon material after high-temperature carbonization is washed with a low-temperature alkali solution to remove substances such as Al and Si that are difficult to evaporate at high temperatures. The present invention utilizes the differences and complementarities of ash removal by high-temperature carbonization (difficult to remove Al and Si substances) and low-temperature alkali washing (difficult to remove Fe and Ca substances) to achieve deep ash removal. After deashing, the impurities in the carbon material are reduced, the carbon structure is purer, which is beneficial to improving the electrochemical performance (such as conductivity and specific capacity) and mechanical properties (such as strength and toughness). The process flow of the present invention is clear, suitable for industrial production, and is conducive to realizing large-scale and low-cost preparation.
[0056] An embodiment of the present invention discloses a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing, which is prepared according to the method for deep deashing of a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing.
[0057] This embodiment utilizes the differences and complementarities of ash removal by high-temperature carbonization (difficult to remove Al and Si substances) and low-temperature alkali washing (difficult to remove Fe and Ca substances) to achieve deep ash removal. After the coal-based carbon material is deeply deashed, the impurities are reduced, the conductivity of the material is increased by 1-2 orders of magnitude, and the resistivity is reduced; the uniformity of the pore distribution is improved, which is beneficial to the infiltration of the electrolyte and reduces the proportion of "dead pores". The mechanical strength (such as compressive strength) is increased by 20%-30%, reducing the volume expansion and pulverization of the material during charge and discharge. Through the synergistic effect of high-temperature gasification and alkali washing, the present invention realizes the efficient and deep deashing of the coal-based carbon material, significantly improves the purity and performance of the material, and at the same time has the advantages of process controllability and environmental protection, providing a reliable solution for the preparation of high-performance carbon materials.
[0058] An embodiment of the present invention discloses the application of a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing in the preparation of the anode material for a sodium-ion battery.
[0059] In this embodiment, when the coal-based carbon material is used to prepare the anode material of a sodium-ion battery, a hard carbon anode, a soft carbon anode or a porous carbon anode can be fabricated. When fabricating a hard carbon anode, anthracite is used as the precursor, and hard carbon materials are prepared by high-temperature carbonization, which have a large interlayer spacing and rich defect structures, and a large specific sodium storage capacity. When fabricating a soft carbon anode, bituminous coal or lignite is used as the precursor, and soft carbon materials are prepared by low-temperature carbonization, which have a high degree of graphitization and electrical conductivity, and excellent rate performance. When fabricating a porous carbon anode, porous coal-based carbon materials are prepared by an activation method, which have a high specific surface area and rich pore structures, and the sodium storage capacity and cycle stability are significantly improved.
[0060] The following will further illustrate the present invention with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.
[0061] Conventional instruments and equipment in the art are used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.
[0062] Example 1:
[0063] (1) The coal-based carbon material is laid flat in a tray and heated to 1400 °C in an inert atmosphere. Most of the ash in the coal will decompose and gasify, escaping into the gas phase to obtain the carbonized coal-based carbon material;
[0064] (2) The coal-based carbon material after high-temperature carbonization is mixed with a 2 mol / L NaOH solution in a ratio of 1 g: 60 mL, heated to 60 °C and maintained for 6 h, with continuous stirring during the process; filtered and the carbon material is repeatedly washed with deionized water until neutral to achieve deep removal of the remaining ash.
[0065] (3) The sample obtained in step (2) is dried to obtain a deeply deashed coal-based carbon material.
[0066] See Figure 2a 、 Figure 2b 、 Figure 2c 、 Figure 2d 、 Figure 2e, compare the contents of residual ash, Al element, Si element, Fe element, Ca element, etc. in the coal-based carbon material after different deashing methods.
[0067] As can be seen from Figure 2, high-temperature deashing (AC-HT) can remove nearly 90% of the ash, while alkali washing can remove nearly 80% of the ash. The combination of the two can remove more than 98% of the ash, reducing the ash content in the activated carbon to 0.09%.
[0068] The main reason is that high-temperature treatment is not conducive to the removal of Al and Si substances, but has excellent removal effects on substances such as Fe and Ca; alkali washing is not conducive to the removal of substances such as Fe and Ca, but has excellent removal effects on Al and Si substances; the removal effects on other elements (such as K and Mg) are similar for both. There are obvious complementary advantages in the types of removed substances between the two, achieving deep removal of ash in the carbon material.
[0069] Example 2:
[0070] (1) Spread the coal-based carbon material on a tray and heat it to 1300 °C in an inert atmosphere. Most of the ash in the coal will decompose and gasify, escaping into the gas phase to obtain the carbonized coal-based carbon material;
[0071] (2) Mix the carbonized coal-based carbon material with 3 mol / L NaOH solution at a ratio of 1 g:50 mL, heat it to 70 °C and keep it for 5 h, and continuously stir during the process; filter and wash the carbon material with deionized water repeatedly until it is neutral to achieve deep removal of the remaining ash.
[0072] (3) Dry the sample obtained in step (2) to obtain the deeply deashed coal-based carbon material.
[0073] Aiming at the problem that conventional deashing methods cannot achieve deep removal of ash, this example combines high-temperature carbonization and low-temperature alkali washing organically to deeply remove the ash in the coal-based carbon material. After deashing, the impurities in the carbon material are reduced, and the carbon structure is purer, which is beneficial to improving the electrochemical properties (such as conductivity and specific capacity) and mechanical properties (such as strength and toughness). The process flow of this example is clear, suitable for industrial production, and conducive to realizing large-scale and low-cost preparation.
[0074] Example 3:
[0075] (1) Spread the coal-based carbon material on a tray and heat it to 1600 °C in an inert atmosphere. Most of the ash in the coal will decompose and gasify, escaping into the gas phase to obtain the carbonized coal-based carbon material;
[0076] (2) Mix the coal-based carbon material after high-temperature carbonization with 5 mol / L NaOH solution at a ratio of 1 g: 90 mL, heat it to 90 °C and keep it for 3 h, and continuously stir during the process; filter and wash the carbon material with deionized water repeatedly until it is neutral to achieve deep removal of the remaining ash.
[0077] (3) Dry the sample obtained in step (2) to obtain a deeply deashed coal-based carbon material.
[0078] Example 4:
[0079] (1) Lay the coal-based carbon material flat in a tray, heat it to 1700 °C under an inert atmosphere, decompose and gasify most of the ash in the coal, and escape it into the gas phase to obtain the carbonized coal-based carbon material;
[0080] (2) Mix the coal-based carbon material after high-temperature carbonization with 4 mol / L NaOH solution at a ratio of 1 g: 80 mL, heat it to 80 °C and keep it for 3 h, and continuously stir during the process; filter and wash the carbon material with deionized water repeatedly until it is neutral to achieve deep removal of the remaining ash.
[0081] (3) Dry the sample obtained in step (2) to obtain a deeply deashed coal-based carbon material.
[0082] Example 5:
[0083] (1) Lay the coal-based carbon material flat in a tray, heat it to 1200 °C under an inert atmosphere, decompose and gasify most of the ash in the coal, and escape it into the gas phase to obtain the carbonized coal-based carbon material;
[0084] (2) Mix the coal-based carbon material after high-temperature carbonization with 1 mol / L NaOH solution at a ratio of 1 g: 30 mL, heat it to 75 °C and keep it for 9 h, and continuously stir during the process; filter and wash the carbon material with deionized water repeatedly until it is neutral to achieve deep removal of the remaining ash.
[0085] (3) Dry the sample obtained in step (2) to obtain a deeply deashed coal-based carbon material.
[0086] Example 6:
[0087] (1) Lay the coal-based carbon material flat in a tray, heat it to 1800 °C under an inert atmosphere, decompose and gasify most of the ash in the coal, and escape it into the gas phase to obtain the carbonized coal-based carbon material;
[0088] (2) Mix the coal-based carbon material after high-temperature carbonization with 1 mol / L NaOH solution at a ratio of 1 g: 100 mL, heat it up to 70 °C and maintain for 10 h, and continuously stir during the process; filter and wash the carbon material repeatedly with deionized water until it is neutral to achieve deep removal of residual ash.
[0089] (3) Dry the sample obtained in step (2) to obtain the deep-ash-removed coal-based carbon material.
[0090] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for deep deashing of coal-based carbon materials based on high-temperature carbonization and low-temperature alkali washing, characterized in that, It includes the following steps: Carbonize the coal-based carbon material to obtain the carbonized coal-based carbon material; Mix the carbonized coal-based carbon material with an alkali solution, heat it to the first preset temperature and keep it warm, filter and wash to obtain the alkali-washed coal-based carbon material; Dry the alkali-washed coal-based carbon material to obtain the deeply deashed coal-based carbon material.
2. The deep deashing method of a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing according to claim 1, characterized in that, The step of carbonizing the coal-based carbon material to obtain the carbonized coal-based carbon material specifically includes: Heat the coal-based carbon material to the second preset temperature in an inert atmosphere to allow the ash in the coal-based carbon material to escape into the gas phase, thereby obtaining the carbonized coal-based carbon material.
3. The deep deashing method of coal-based carbon materials based on high-temperature carbonization and low-temperature alkali washing according to claim 2, characterized in that The second preset temperature is 1200°C to 1800°C.
4. A method for deep deashing of coal-based carbon materials based on high-temperature carbonization and low-temperature alkali washing according to claim 1, characterized in that, The alkali solution is a 1 mol / L to 5 mol / L NaOH solution.
5. A method for deep deashing of coal-based carbon materials based on high-temperature carbonization and low-temperature alkali washing according to claim 1, characterized in that, The mixing ratio of the alkali solution to the carbonized coal-based carbon material is 1 g:(30 - 100) mL.
6. The deep deashing method of a coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing according to claim 1, characterized in that, The first preset temperature is 60°C to 90°C.
7. A method for deep deashing of coal-based carbon materials based on high-temperature carbonization and low-temperature alkali washing according to claim 1, characterized in that, The heat preservation time is 1 h to 10 h.
8. A method for deep deashing of coal-based carbon materials based on high-temperature carbonization and low-temperature alkali washing according to claim 1, characterized in that, The washing process is as follows: repeatedly wash the filtered product with deionized water until it is neutral.
9. A coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing, characterized in that, It is prepared according to the method for deep deashing of coal-based carbon materials based on high-temperature carbonization and low-temperature alkali washing described in any one of claims 1 to 8.
10. Use of the coal-based carbon material based on high-temperature carbonization and low-temperature alkali washing described in claim 9 in the preparation of a negative electrode material for a sodium-ion battery.