Coal-based hard carbon negative electrode material and preparation method thereof

Abstract

The application relates to a coal-based hard carbon negative material and a preparation method thereof, and belongs to the technical field of electrode materials; the method comprises the following steps: pre-desalting a coal-based material to obtain a pre-desalted material; performing calcination carbonization treatment on the pre-desalted material to obtain a carbonized material; performing secondary purification desalting on the carbonized material to obtain a secondary desalted material; performing pre-oxidation treatment on the secondary desalted material to obtain a coal-based hard carbon negative material; the coal-based material is treated through a process path of pre-desalting-carbonization treatment-purification secondary desalting-pre-oxidation, the preparation process is simple, and the cost is low. When the hard carbon negative material obtained through the method is applied to a battery, the battery can have high initial efficiency and capacity.

Description

Technical Field

[0001] This application relates to the field of electrode materials technology, and in particular to a coal-based hard carbon anode material and its preparation method. Background Technology

[0002] Electrochemical energy storage boasts advantages such as high conversion efficiency, flexible assembly, and rapid cost reduction. Current secondary battery energy storage technologies are dominated by lithium-ion and lead-acid batteries. However, lithium-ion batteries suffer from low energy density, high cost, poor safety, and insufficient lifespan. Lead-acid batteries have low energy density and contain large amounts of harmful or non-degradable heavy metals, leading to unavoidable environmental problems during production and application. Therefore, the future development of lithium-ion and lead-acid batteries will face obstacles. Developing low-cost, high-performance, and safe alternative batteries is an urgent need for the future development of secondary battery energy storage.

[0003] Sodium-ion batteries have many advantages, including abundant resources, low cost, high energy conversion efficiency, long cycle life, low maintenance costs, and high safety. They can meet the application requirements of high cost-effectiveness and high safety in fields such as new energy vehicles, electric vehicles, energy storage batteries, and electronic products. Their energy density is higher than that of lead-acid batteries and can achieve a similar energy density to lithium iron phosphate batteries, making them quite competitive in fields such as new energy vehicles, electric vehicles, energy storage batteries, and electronic products.

[0004] Anode materials are the key materials that restrict the development of sodium-ion batteries. Currently, hard carbon is the sodium-ion battery anode material with commercial prospects, but the acquisition of hard carbon anode materials for sodium-ion batteries is limited. Summary of the Invention

[0005] This application provides a coal-based hard carbon anode material and its preparation method, thereby providing a new path for obtaining hard carbon anode materials and improving the current problem of the single method for obtaining such materials.

[0006] In a first aspect, this application provides a method for preparing a coal-based hard carbon anode material, the method comprising:

[0007] Coal-based materials are pre-deashed to obtain pre-deashed materials;

[0008] The pre-deashed material is subjected to calcination and carbonization treatment to obtain carbonized material;

[0009] The carbonized material is subjected to secondary purification and deashing to obtain a secondary deashed material;

[0010] The secondary deashing material is pre-oxidized to obtain a coal-based hard carbon anode material.

[0011] As an optional implementation, the pre-deashing of coal-based materials to obtain pre-deashed materials includes:

[0012] Coal-based materials are mixed with a submolten salt of alkali and heated to react, yielding the first solid product;

[0013] The first solid product was subjected to acid washing to obtain a pre-deashed material.

[0014] As an optional implementation, the mass ratio of the submolten salt of the alkali to the coal-based material is (0.3–3):1; and / or

[0015] The temperature of the mixed heating reaction is 90℃~220℃; and / or

[0016] The mixing and heating reaction time is 5 h to 10 h; and / or

[0017] The mass ratio of the first acid solution to the coal-based material is (0.5–3):1; and / or

[0018] The pickling temperature is 80℃~150℃; and / or

[0019] The pickling process takes 5 to 10 hours.

[0020] As an optional implementation, the mass percentage of ash in the pre-deashed material is ≤1%.

[0021] As an optional implementation, the coal-based material includes at least one of diesel coal, bituminous coal, and anthracite.

[0022] As an optional implementation, the calcination and carbonization treatment temperature is 700℃~1100℃; and / or

[0023] The heating rate of the calcination and carbonization treatment is 2℃ / min to 6℃ / min; and / or

[0024] The calcination and carbonization treatment time is 1 hour to 3 hours.

[0025] As an optional implementation, the secondary purification and deashing is performed using an acid-base method; and / or

[0026] The secondary purification and deashing process is accompanied by stirring, and the acid treatment is performed first, followed by the alkali treatment. The acid treatment temperature is 20℃~30℃, the stirring speed is 200rpm~300rpm, and the acid treatment time is 8h~12h. The alkali treatment temperature is 50℃~80℃, the stirring speed is 150rpm~260rpm, and the alkali treatment time is 6h~10h.

[0027] As an optional implementation, the mass percentage of ash in the secondary deashing material is ≤0.3%.

[0028] As an optional implementation, the pre-oxidation treatment temperature is 200℃~300℃; and / or

[0029] The pre-oxidation treatment time is 0.5h to 2h.

[0030] Secondly, this application provides a coal-based hard carbon anode material, which is prepared using the method provided in the first aspect.

[0031] The technical solutions provided in this application have the following advantages compared with the prior art:

[0032] The method provided in this application employs a process route of pre-deashing-carbonization treatment-purification secondary deashing-pre-oxidation to process coal-based materials. The preparation process is simple and low-cost. Furthermore, the hard carbon anode material obtained by this method, when applied in batteries, enables the batteries to exhibit high initial efficiency and capacity. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart illustrating the method provided in an embodiment of this application. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0038] Figure 1 A flowchart illustrating the method provided in the embodiments of this application, as shown below. Figure 1As shown in the embodiments of this application, a method for preparing a coal-based hard carbon anode material is provided, the method comprising:

[0039] S1. Pre-deashing coal-based materials to obtain pre-deashed materials;

[0040] The coal-based material includes at least one of bituminous coal, coal, and anthracite.

[0041] In some embodiments, pre-deashing of coal-based materials yields pre-deashed materials comprising:

[0042] S1.1. A coal-based material is mixed with a submolten salt of an alkali and heated to obtain a first solid product; wherein the mass ratio of the submolten salt of the alkali to the coal-based material is (0.3-3):1; the temperature of the mixing and heating reaction is 90℃-220℃, and the time of the mixing and heating reaction is 5h-10h.

[0043] For example, the alkali can be selected from at least one of sodium hydroxide, potassium hydroxide, strong calcium oxide, and barium hydroxide. The mass ratio of the submolten salt of the alkali to the coal-based material can be 0.3:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1, or any value within the range of (0.3 to 3):1. The temperature of the mixed heating reaction can be 90℃, 110℃, 130℃, 150℃, 170℃, 190℃, or 220℃, or any value within the range of 90℃ to 220℃. The time of the mixed heating reaction can be 5h, 6h, 7h, 8h, 9h, or 10h, or any value within the range of 5h to 10h.

[0044] S1.2. The first solid product is subjected to acid washing treatment with acid solution to obtain pre-deashed material. The mass ratio of the first acid solution to the coal-based material is (0.5–3):1; the acid washing treatment temperature is 80℃–150℃; and the acid washing treatment time is 5h–10h.

[0045] The mass percentage of ash in the pre-de-ashed material is less than or equal to 1%.

[0046] For example, the acid solution can be selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, and perchloric acid. The mass ratio of the first acid solution to the coal-based material can be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1, or any value within the range of (0.5 to 3):1. The pickling temperature can be 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃, or any value within the range of 80℃ to 150℃. The pickling time can be 5h, 6h, 7h, 8h, 9h, or 10h, or any value within the range of 5h to 10h.

[0047] Specifically, in this embodiment, the preparation process of the pre-deashing material can be as follows: mixing and heating coal-based material with a sub-molten salt of alkali to react, performing solid-liquid separation on the slurry after reaction, washing the solid product to neutral to obtain a first solid product, using acid to acid wash the obtained first solid product, performing solid-liquid separation on the slurry after reaction, washing the acid-washed solid product to neutral to obtain the pre-deashing material.

[0048] S2. The pre-deashed material is subjected to calcination and carbonization treatment to obtain carbonized material;

[0049] In some embodiments, the temperature of the calcination carbonization treatment is 700℃~1100℃; the heating rate of the calcination carbonization treatment is 2℃ / min~6℃ / min; and the time of the calcination carbonization treatment is 1h~3h.

[0050] For example, the temperature of the calcination and carbonization treatment can be 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, or 1100℃, or any value within the range of 700℃ to 1100℃. The heating rate of the calcination and carbonization treatment can be 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min, 5℃ / min, 5.5℃ / min, or 6℃ / min, or any value within the range of 2℃ / min to 6℃ / min. The time of the calcination and carbonization treatment can be 1h, 1.5h, 2h, 2.5h, or 3h, or any value within the range of 1h to 3h.

[0051] S3. The carbonized material is subjected to secondary purification and deashing to obtain a secondary deashed material;

[0052] In some embodiments, the secondary purification and deashing employs an acid-base method. Further, the secondary purification and deashing process involves stirring, and the acid treatment is performed first, followed by the alkali treatment. Specifically, the acid treatment temperature is 20℃–30℃, the stirring speed is 200 rpm–300 rpm, and the treatment time is 8 h–12 h; the alkali treatment temperature is 50℃–80℃, the stirring speed is 150 rpm–260 rpm, and the treatment time is 6 h–10 h. The ash content of the deashed material after secondary purification and deashing is less than or equal to 0.3% by mass.

[0053] For example, the acid treatment temperature can be 20℃, 22℃, 24℃, 26℃, 28℃, or 30℃, or any value within the range of 20℃ to 30℃. The stirring speed for acid treatment can be 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm, or 300 rpm, or any value within the range of 200 rpm to 300 rpm. The acid treatment time can be 8h, 9h, 10h, 11h, or 12h, or any value within the range of 8h to 12h. The alkali treatment temperature can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, or 80℃, or any value within the range of 50℃ to 80℃. The stirring speed for alkali treatment can be 150 rpm, 170 rpm, 200 rpm, 220 rpm, 240 rpm, or 260 rpm, or any value within the range of 150 rpm to 260 rpm. The alkali treatment time can be 6h, 7h, 8h, 9h or 10h, or any value within the range of 6h to 10h.

[0054] Specifically, in this embodiment, the secondary purification and deashing process can be as follows: the carbonized material is mixed and stirred with acid solution, and after stirring, the slurry is separated into solid and liquid components. The solid product is washed to neutral. Then, the solid product is mixed and stirred with alkaline solution, and after stirring, the slurry is separated into solid and liquid components. The solid product is washed to neutral to obtain the secondary deashing material.

[0055] For example, the acid solution for acid treatment can be selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, and perchloric acid. The alkaline solution for alkali treatment can be selected from at least one of sodium hydroxide, potassium hydroxide, strong calcium oxide, and barium hydroxide.

[0056] S4. The secondary deashing material is pre-oxidized to obtain a coal-based hard carbon anode material.

[0057] In some embodiments, the temperature of the pre-oxidation treatment is 200℃~300℃; the time of the pre-oxidation treatment is 0.5h~2h.

[0058] For example, the temperature of the pre-oxidation treatment can be 200℃, 220℃, 240℃, 260℃, 280℃, or 300℃, or any value within the range of 200℃ to 300℃. The time of the pre-oxidation treatment can be 0.5h, 1h, 1.5h, or 2h, or any value within the range of 0.5h to 2h.

[0059] Specifically, in this embodiment, the pre-oxidation process can be as follows: the secondary deashing material is spread evenly in the corundum crucible, the crucible is placed in the atmosphere furnace, the atmosphere furnace is purged with an oxygen atmosphere, the atmosphere furnace temperature is set to 200℃~300℃, and the heating time is 0.5h~2h.

[0060] This method employs a process route of pre-deashing-carbonization treatment-purification secondary deashing-pre-oxidation to process coal-based materials. The preparation process is simple and low-cost. Furthermore, the hard carbon anode material obtained by this method, when applied to batteries, enables the batteries to exhibit high initial efficiency and capacity.

[0061] Based on a general inventive concept, embodiments of this application also provide a coal-based hard carbon anode material, which is prepared using the method provided above.

[0062] The coal-based hard carbon anode material is prepared based on the above method. The specific steps of the method can be referred to the above embodiments. Since the coal-based hard carbon anode material adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0063] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0064] Example 1

[0065] A method for preparing a coal-based hard carbon anode material includes the following steps:

[0066] Coal-based material pre-deashing: Take 500g of coal, 800g of sodium hydroxide, and 200g of deionized water, mix them, and stir at 150℃ for 8 hours. After stirring, cool and wash to obtain the alkali reaction solid product. Take 6wt% hydrochloric acid and mix it with the alkali reaction solid product at a 1:1 ratio. After mixing, stir at 90℃ for 7 hours. After stirring, cool and wash the solid product with deionized water until neutral to obtain the pre-deashed material.

[0067] Carbonization of pre-deashed material: Take the pre-deashed material and put it into a corundum crucible. Then, place the crucible into a large crucible and fill it with calcined coke as filler. Set the carbonization program as follows: heating rate of 3℃ / min, calcination temperature of 700℃, holding time of 2h. After calcination, carbonized material is obtained.

[0068] Secondary purification and deashing of carbonized materials: Take 30g of carbonized material, put it into a polytetrafluoroethylene beaker, add 300ml of 0.2wt% sodium hydroxide, stir at 50℃ for 6h at a speed of 250rpm, after stirring, wash the raw material with deionized water to neutralize it, then add the alkaline washed raw material into a polytetrafluoroethylene beaker, add 300ml of 4mol / L hydrochloric acid, stir at room temperature for 10h at a speed of 300rpm, after stirring, wash the raw material with deionized water to neutralize it, and obtain the secondary deashed material.

[0069] Pre-oxidation treatment of secondary deashed material: The secondary deashed material is spread evenly in a corundum crucible, the crucible is placed in an atmosphere furnace, an oxygen atmosphere is introduced into the atmosphere furnace, the atmosphere furnace temperature is set to 200℃, the heating time is 0.5h, and the coal-based hard carbon anode material is obtained after heating is completed.

[0070] Example 2

[0071] A method for preparing a coal-based hard carbon anode material for sodium-ion batteries includes the following steps:

[0072] Coal-based material pre-deashing: Take 500g of bituminous coal, 700g of sodium hydroxide, and 300g of deionized water, mix them, and stir at 180℃ for 9 hours. After stirring, cool and wash to obtain the alkali reaction solid product. Take 6wt% hydrochloric acid and mix it with the alkali reaction solid product at a ratio of 1.2:1. After mixing, stir at 80℃ for 8 hours. After stirring, cool and wash the solid product with deionized water until neutral to obtain the pre-deashed material.

[0073] Carbonization of pre-deashed material: Take the pre-deashed material and put it into a corundum crucible. Then, place the crucible into a large crucible and fill it with calcined coke as filler. Set the carbonization program as follows: heating rate of 5℃ / min, calcination temperature of 800℃, holding time of 1.5h. After calcination, carbonized material is obtained.

[0074] Secondary purification and deashing of carbonized materials: Take 30g of carbonized material, put it into a polytetrafluoroethylene beaker, add 300ml of 0.2wt% calcium hydroxide, stir at 60℃ for 8h at a speed of 240rpm. After stirring, wash the raw material with deionized water to neutralize it. Then add the alkaline-washed raw material into a polytetrafluoroethylene beaker, add 300ml of 4mol / L sulfuric acid, stir at room temperature for 10h at a speed of 280rpm, and after stirring, wash the raw material with deionized water to neutralize it to obtain the secondary deashed material.

[0075] Pre-oxidation treatment of secondary deashed material: The secondary deashed material is spread evenly in a corundum crucible, the crucible is placed in an atmosphere furnace, an oxygen atmosphere is introduced into the atmosphere furnace, the atmosphere furnace temperature is set to 240℃, the heating time is 0.8h, and the coal-based hard carbon anode material is obtained after heating is completed.

[0076] Example 3

[0077] A method for preparing a coal-based hard carbon anode material for sodium-ion batteries includes the following steps:

[0078] Coal-based material pre-deashing: Take 500g of anthracite, 700g of sodium hydroxide, and 200g of deionized water, mix them, and stir at 180℃ for 9 hours. After stirring, cool and wash to obtain the alkali reaction solid product. Take 6wt% hydrochloric acid and mix it with the alkali reaction solid product at a ratio of 1.5:1. After mixing, stir at 100℃ for 8 hours. After stirring, cool and wash the solid product with deionized water until neutral to obtain the pre-deashed material.

[0079] Carbonization of pre-deashed material: Take the pre-deashed material and put it into a corundum crucible. Then, put the crucible into a large crucible and fill it with calcined coke as filler. Set the carbonization program as follows: heating rate of 5℃ / min, calcination temperature of 1000℃, holding time of 2h. After calcination, carbonized material is obtained.

[0080] Secondary purification and deashing of carbonized materials: Take 30g of carbonized material, put it into a polytetrafluoroethylene beaker, add 300ml of 0.2wt% potassium hydroxide, stir at 70℃ for 8h at a speed of 210rpm. After stirring, wash the raw material with deionized water to neutralize it. Then add the alkaline-washed raw material into the polytetrafluoroethylene beaker, add 300ml of 4mol / L hydrofluoric acid, stir at room temperature for 11h at a speed of 280rpm, and after stirring, wash the raw material with deionized water to neutralize it to obtain the secondary deashed material.

[0081] Pre-oxidation treatment of secondary deashed material: The secondary deashed material is spread evenly in a corundum crucible and placed in an atmosphere furnace. An oxygen atmosphere is introduced into the atmosphere furnace, the temperature of the atmosphere furnace is set to 260℃, and the heating time is 1 hour. After heating, coal-based hard carbon anode material is obtained.

[0082] Example 4

[0083] A method for preparing a coal-based hard carbon anode material for sodium-ion batteries includes the following steps:

[0084] Coal-based material pre-deashing: Take 200g of anthracite, 300g of coal ash, 800g of sodium hydroxide, and 300g of deionized water. Mix them and stir at 200℃ for 10 hours. After stirring, cool and wash to obtain the alkali reaction solid product. Take 6wt% hydrochloric acid and mix it with the alkali reaction solid product at a ratio of 1.4:1. After mixing, stir at 120℃ for 10 hours. After stirring, cool and wash the solid product with deionized water until neutral to obtain the pre-deashed material.

[0085] Carbonization of pre-deashed material: Take the pre-deashed material and put it into a corundum crucible. Then, place the crucible into a large crucible and fill it with calcined coke as filler. Set the carbonization program as follows: heating rate of 6℃ / min, calcination temperature of 1100℃, holding time of 3h. After calcination, carbonized material is obtained.

[0086] Secondary purification and deashing of carbonized materials: Take 30g of carbonized material and put it into a polytetrafluoroethylene beaker. Add 0.2wt% barium hydroxide and 300ml sodium hydroxide. Stir at 80℃ for 10h at a speed of 260rpm. After stirring, wash the raw material with deionized water until neutral. Then add the alkaline-washed raw material into the polytetrafluoroethylene beaker and add 4mol / L hydrofluoric acid and 300ml nitric acid. Stir at room temperature for 12h at a speed of 300rpm. After stirring, wash the raw material with deionized water until neutral to obtain the secondary deashed material.

[0087] Pre-oxidation treatment of secondary deashed material: The secondary deashed material is spread evenly in a corundum crucible, the crucible is placed in an atmosphere furnace, an oxygen atmosphere is introduced into the atmosphere furnace, the atmosphere furnace temperature is set to 280℃, the heating time is 1.3h, and the coal-based hard carbon anode material is obtained after heating is completed.

[0088] Example 5

[0089] A method for preparing a coal-based hard carbon anode material for sodium-ion batteries includes the following steps:

[0090] Coal-based material pre-deashing: Take 300g of anthracite, 200g of bituminous coal, 700g of sodium hydroxide, and 200g of deionized water. Mix them and stir at 220℃ for 10 hours. After stirring, cool and wash to obtain the alkali reaction solid product. Take 6wt% hydrochloric acid and mix it with the alkali reaction solid product at a ratio of 2:1. After mixing, stir at 150℃ for 10 hours. After stirring, cool and wash the solid product with deionized water until neutral to obtain the pre-deashed material.

[0091] Carbonization of pre-deashed material: Take the pre-deashed material and put it into a corundum crucible. Then, put the crucible into a large crucible and fill it with calcined coke as filler. Set the carbonization program as follows: heating rate of 4℃ / min, calcination temperature of 1000℃, holding time of 2h. After calcination, carbonized material is obtained.

[0092] Secondary purification and deashing of carbonized materials: Take 30g of carbonized material and put it into a polytetrafluoroethylene beaker. Add 300ml of 0.2wt% calcium hydroxide and sodium hydroxide. Stir at 80℃ for 9h at a speed of 240rpm. After stirring, wash the raw material with deionized water until neutral. Then add the alkaline-washed raw material into the polytetrafluoroethylene beaker and add 300ml of 4mol / L nitric acid. Stir at room temperature for 11h at a speed of 300rpm. After stirring, wash the raw material with deionized water until neutral to obtain the secondary deashed material.

[0093] Pre-oxidation treatment of secondary deashed material: The secondary deashed material is spread evenly in a corundum crucible, the crucible is placed in an atmosphere furnace, an oxygen atmosphere is introduced into the atmosphere furnace, the atmosphere furnace temperature is set to 300℃, the heating time is 1.5h, and the coal-based hard carbon anode material is obtained after heating is completed.

[0094] Example 6

[0095] A method for preparing a coal-based hard carbon anode material for sodium-ion batteries includes the following steps:

[0096] Coal-based material pre-deashing: Take 500g of anthracite, 750g of sodium hydroxide, and 200g of deionized water, mix them, and stir at 200℃ for 10 hours. After stirring, cool and wash to obtain the alkali reaction solid product. Take 6wt% hydrochloric acid and mix it with the alkali reaction solid product at a ratio of 3:1. After mixing, stir at 130℃ for 10 hours. After stirring, cool and wash the solid product with deionized water until neutral to obtain the pre-deashed material.

[0097] Carbonization of pre-deashed material: Take the pre-deashed material and put it into a corundum crucible. Then, put the crucible into a large crucible and fill it with calcined coke as filler. Set the carbonization program as follows: heating rate of 5℃ / min, calcination temperature of 1000℃, holding time of 2h. After calcination, carbonized material is obtained.

[0098] Secondary purification and deashing of carbonized materials: Take 30g of carbonized material, put it into a polytetrafluoroethylene beaker, add 300ml of 0.2wt% sodium hydroxide, stir at 50℃ for 10h at a speed of 260rpm. After stirring, wash the raw material with deionized water to neutralize it. Then add the alkaline-washed raw material into the polytetrafluoroethylene beaker, add 300ml of 4mol / L sulfuric acid and hydrochloric acid, stir at room temperature for 10h at a speed of 300rpm, and after stirring, wash the raw material with deionized water to neutralize it to obtain the secondary deashed material.

[0099] Pre-oxidation treatment of secondary deashed material: The secondary deashed material is spread evenly in a corundum crucible, the crucible is placed in an atmosphere furnace, an oxygen atmosphere is introduced into the atmosphere furnace, the atmosphere furnace temperature is set to 300℃, the heating time is 2h, and the coal-based hard carbon anode material is obtained after heating is completed.

[0100] Sodium-ion batteries were prepared using the coal-based hard carbon anode materials for sodium-ion batteries prepared in the above embodiments, and their electrochemical performance was tested. The test results are shown in Table 1.

[0101] Table 1 Electrochemical performance indicators of sodium-ion batteries

[0102]

[0103] As can be seen from Table 1, the coal-based hard carbon anode material prepared by the method provided in the embodiments of this application, when used in sodium-ion batteries, exhibits high initial discharge efficiency, high initial capacity, high capacity retention rate after 50 battery cycles, and high reversible capacity, meeting the requirements for use in sodium-ion batteries. Moreover, the preparation method is simple and inexpensive.

[0104] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0105] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b or c" or "at least one of a, b and c" can both mean: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0106] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a coal-based hard carbon anode material, characterized in that, The method includes: A coal-based material is mixed with a sub-molten salt of an alkali and heated to react, yielding a first solid product. The mass ratio of the sub-molten salt of the alkali to the coal-based material is (0.3~3):

1. The first solid product is subjected to acid washing treatment with acid solution to obtain pre-deashed material. The mass ratio of the acid solution to the coal-based material is (0.5~3):1, and the acid washing treatment temperature is 80℃~150℃. The mass percentage of ash in the pre-deashed material is ≤1%. The pre-deashed material is subjected to calcination and carbonization treatment to obtain carbonized material, wherein the calcination and carbonization treatment temperature is 850℃~1100℃; The carbonized material is subjected to secondary purification and deashing to obtain a secondary deashed material. The secondary purification and deashing process involves stirring and includes an initial acid treatment followed by an alkali treatment. The acid treatment temperature is 20℃~30℃, the stirring speed is 200rpm~300rpm, and the treatment time is 8h~12h. The alkali treatment temperature is 50℃~80℃, the stirring speed is 150rpm~260rpm, and the treatment time is 6h~10h. The ash content in the secondary deashed material is ≤0.3% by mass. The secondary deashing material is subjected to pre-oxidation treatment to obtain coal-based hard carbon anode material. The pre-oxidation treatment includes: spreading the secondary deashing material in a corundum crucible, placing the crucible in an atmosphere furnace, introducing an oxygen atmosphere into the atmosphere furnace, setting the atmosphere furnace temperature to 200℃~300℃, and heating time to 0.5h~2h.

2. The method for preparing the coal-based hard carbon anode material according to claim 1, characterized in that, The temperature of the mixed heating reaction is 90℃~220℃; The mixing and heating reaction time is 5h~10h; The pickling process takes 5 to 10 hours.

3. The method for preparing the coal-based hard carbon anode material according to claim 1, characterized in that, The coal-based material includes at least one of bituminous coal, coal, and anthracite.

4. The method for preparing the coal-based hard carbon anode material according to claim 1, characterized in that, The heating rate of the calcination and carbonization treatment is 2℃ / min to 6℃ / min; and / or The calcination and carbonization treatment time is 1h to 3h.

5. A coal-based hard carbon anode material, characterized in that, The coal-based hard carbon anode material is prepared by the method described in any one of claims 1 to 4.

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