Camphor tree seed-based porous hard carbon material and preparation method thereof
By using camphor tree seeds to prepare porous hard carbon materials, using hydrothermal treatment and high-temperature carbonization methods, combined with alcohol as pore-forming agent, the problem of insufficient reversible capacity and energy density of hard carbon materials in sodium ion batteries is solved, and a high electrochemical performance and environmentally friendly preparation method is achieved.
Patent Information
- Application Number
- CN202411914250.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-03-28
AI Technical Summary
The reversible capacity and energy density of existing hard carbon materials in sodium ion batteries are insufficient in the platform area, and the traditional pore-making methods have problems of environmental pollution and high costs.
Porous hard carbon materials are prepared by using camphor seeds as precursors, hydrothermal treatment and high-temperature carbonization, and carbonization is carried out using alcohol as a pore-forming agent to form hard carbon materials with suitable pore structures.
The high electrochemical performance of camphor tree seed-based porous hard carbon material is achieved, and the reversible capacity and energy density of the platform area of the sodium ion battery are improved. At the same time, the method is simple and environmentally friendly, avoiding environmental pollution and high cost problems.
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Figure CN119706796A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of sodium ion battery material preparation, and particularly relates to a camphor seed-based porous hard carbon material and a preparation method thereof. Background Art
[0002] Hard carbon is one of the most promising anode materials for sodium-ion batteries due to its high reversible capacity, low operating potential, excellent cycle life, and abundant resources. Generally speaking, the discharge / charge curve of hard carbon can be divided into a slope region (> 0.1 V) and a plateau region (< 0.1 V). Improving the reversible capacity in the plateau region below 0.1 V is crucial for improving the energy density and operating voltage window of sodium-ion batteries. This is closely related to the filling of sodium ions in closed pores and the intercalation of sodium ions between carbon layers. Regarding pore structure, the number and volume of closed pores in hard carbon are important factors affecting the sodium storage capacity in the plateau region. Therefore, a pore structure with the appropriate size is crucial for designing high-capacity hard carbon. Researchers typically introduce closed pores into hard carbon through methods such as temperature regulation, the use of pore-forming agents (such as MgO, ZnO, and KOH), and surface coating to open pores. However, acid leaching of these templates increases the risk of environmental pollution and is costly, hindering their practical application. Therefore, the preparation of hard carbon with high electrochemical performance through a simple and environmentally friendly synthesis method is of great significance for promoting the practical application of hard carbon in sodium-ion batteries.
[0003] Camphor trees are widely distributed in southern China. China's annual camphor seed production reportedly exceeds 10 million tons. Camphor seeds are rich in carbon, oxygen, nitrogen, and other elements, as well as ester organic compounds. However, their utilization is low, and mature camphor seeds naturally fall off each year, wasting resources and polluting the environment. Summary of the Invention
[0004] The object of the present invention is to provide a camphor seed-based porous hard carbon material and a preparation method thereof. The hard carbon material has a pore structure of appropriate size, and the prepared battery has good platform region reversible capacity and energy density.
[0005] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are: A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) cleaning, drying, and then crushing the camphor tree seeds to obtain a raw material powder; (2) subjecting the raw material powder to hydrothermal treatment to obtain a pre-carbonized material; (3) In an inert atmosphere, the pre-carbonized material is carbonized at high temperature to obtain hard carbon.
[0006] It should be noted that the particle size of the raw material powder in step (1) is less than 300 mesh.
[0007] It should be noted that the drying temperature in step (1) is 80-100°C and the drying time is 24-48 hours.
[0008] It should be noted that the hydrothermal solvent in step (2) is at least one of deionized water and alcohol.
[0009] It should be noted that the hydrothermal temperature in step (2) is 160-200°C.
[0010] It should be noted that the hydrothermal time in step (2) is 4-8 hours.
[0011] It should be noted that the mass volume ratio of the raw material powder to the solvent in step (2) is 1 g:10-30 ml.
[0012] It should be noted that the inert atmosphere in step (3) is at least one of nitrogen or argon.
[0013] It should be noted that the carbonization temperature in step (3) is 1000-1600°C, the holding time is 0.5-3h, and the heating rate is 1-10°C / min.
[0014] Beneficial effects of the present invention: (1) The present invention utilizes camphor tree seeds as precursors to prepare porous hard carbon materials. This not only enriches the selection of hard carbon material precursors but also maximizes the economic value of waste camphor tree seeds. (2) Camphor seeds are rich in carbon, oxygen, nitrogen and other elements, showing uniform self-doping properties; nitrogen doping can improve the conductivity of the carbon matrix and introduce additional active sites into the carbon skeleton, thereby enhancing sodium storage capacity; (3) The preparation method of the present invention is simple and environmentally friendly. Alcohol is used as a pore-forming agent to introduce a large number of uniformly dispersed closed pores into the hard carbon, which greatly increases the sodium storage sites in the platform area, thereby improving the reversible capacity and energy density of the platform area of the sodium ion battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 This is a charge and discharge curve diagram of the sodium ion battery prepared in Example 4 of the present invention; Figure 2 This is a cycle diagram of the sodium ion battery prepared in Example 4 of the present invention. DETAILED DESCRIPTION
[0016] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention are further described in detail below in conjunction with specific embodiments: Example 1
[0017] A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 24 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to a solvent (the mass volume ratio of the raw material powder to the solvent was 1 g:10 ml), the volume ratio of water to alcohol in the solvent was 1:2, and the mixture was treated at 160°C for 4 h. After cooling to room temperature, the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1000°C at a heating rate of 2°C / min and kept at this temperature for 2 hours to obtain hard carbon. Example 2
[0018] A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 36 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to a solvent (the mass volume ratio of the raw material powder to the solvent was 1 g:10 ml), the volume ratio of water to alcohol in the solvent was 1:1, and the mixture was treated at 180°C for 4 h. After cooling to room temperature, the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1000°C at a heating rate of 2°C / min and kept at this temperature for 2 hours to obtain hard carbon. Example 3
[0019] A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 48 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to a solvent (the mass volume ratio of raw material powder to solvent was 1 g:10 ml), the volume ratio of water to alcohol in the solvent was 2:1, and the treatment time was 4 h at 200 °C. After cooling to room temperature, the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1000°C at a heating rate of 2°C / min and kept at this temperature for 2 hours to obtain hard carbon. Example 4
[0020] A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 24 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to a solvent (the mass volume ratio of the raw material powder to the solvent was 1 g:10 ml), the volume ratio of water to alcohol in the solvent was 2:1, and the mixture was treated at 180°C for 4 h. After cooling to room temperature, the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1200°C at a heating rate of 2°C / min and kept at this temperature for 1 hour to obtain hard carbon. Example 5
[0021] A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 24 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to a solvent (the mass volume ratio of raw material powder to solvent was 1 g:20 ml), the volume ratio of water to alcohol in the solvent was 2:1, and the mixture was treated at 180°C for 4 h. After cooling to room temperature, the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1200°C at a heating rate of 2°C / min and kept at this temperature for 1 hour to obtain hard carbon. Example 6
[0022] A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 24 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to a solvent (the mass volume ratio of raw material powder to solvent was 1 g:30 ml), the volume ratio of water to alcohol in the solvent was 2:1, and the mixture was treated at 180°C for 4 h. After cooling to room temperature, the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1400°C at a heating rate of 2°C / min and kept at this temperature for 2 hours to obtain hard carbon. Example 7
[0023] A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 24 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to a solvent (the mass volume ratio of the raw material powder to the solvent was 1 g:10 ml), the volume ratio of water to alcohol in the solvent was 2:1, and the mixture was treated at 180°C for 4 h. After cooling to room temperature, the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1600°C at a heating rate of 2°C / min and kept at this temperature for 1 hour to obtain hard carbon.
[0024] Comparative Example 1 A method for preparing a camphor seed-based porous hard carbon material, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 24 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to water (the mass volume ratio of raw material powder to solvent was 1 g:10 ml), treated at 180°C for 4 h, cooled to room temperature, and the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1200°C at a heating rate of 2°C / min and kept at this temperature for 1 hour to obtain hard carbon.
[0025] Comparative Example 2 A camphor seed-based porous hard carbon material and a preparation method thereof, comprising: (1) After cleaning, camphor tree seeds were dried at 80°C for 24 h, and then crushed to less than 300 mesh to obtain raw material powder; (2) The raw material powder was added to alcohol (the mass volume ratio of raw material powder to solvent was 1 g:10 ml), treated at 180°C for 4 h, cooled to room temperature, and the product was taken out and dried to obtain a pre-carbonized material; (3) Under an inert atmosphere, the pre-carbonized material is heated to 1200°C at a heating rate of 2°C / min and kept at this temperature for 1 hour to obtain hard carbon.
[0026] Effect Example 1 (1) Battery constant current charge and discharge test A hard carbon material, acetylene black, styrene-butadiene rubber, and sodium carboxymethyl cellulose were mixed in a mass ratio of 90:5:3:2. An appropriate amount of water was added to the mixture, and the mixture was ground to obtain a uniform slurry. The prepared slurry was evenly coated on an aluminum foil current collector, dried, and punched into electrodes. Glass fiber was used as a separator and a sodium sheet as a counter electrode. CR2025 button cells were assembled in an argon-filled glove box. After the assembled cells were left for 12 hours, constant current charge and discharge tests were performed on a button cell tester at a current density of 0.1 C (30 mA / g) and a voltage range of 0.01-2.5 V.
[0027] (2) Closed cell volume test The hard carbon materials obtained in Examples 1-6 and Comparative Examples 1-2 were subjected to true density tests using helium as the analytical gas. The true density of ideal graphite is 2.26 g cm -3Therefore, the closed pore volume of the hard carbon sample can be calculated by the following formula:
[0028] Table 1 Test results of electrochemical properties of materials project <![CDATA[Closed pore volume (cm 3 / g)]]> First coulombic efficiency (%) 0.1C reversible specific capacity (mAh / g) Example 1 0.312 82.1 314 Example 2 0.344 83.4 322 Example 3 0.341 83.5 313 Example 4 0.320 88.9 358 Example 5 0.326 86.2 349 Example 6 0.338 83.7 322 Example 7 0.347 85.1 338 Comparative Example 1 0.314 76.8 284 Comparative Example 2 0.426 72.3 209 Judging from the test results, the camphor seed-based porous hard carbon material prepared by the method of the present invention has better first coulombic efficiency and reversible specific capacity than the comparative example.
[0029] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for preparing a camphor seed-based porous hard carbon material, characterized in that: The following steps are involved: (1) washing, drying and then crushing the camphor tree seeds to obtain a raw material powder, wherein the particle size of the raw material powder is less than 300 mesh; (2) subjecting the raw material powder to a hydrothermal treatment to obtain a pre-carbonized material, wherein the solvent of the hydrothermal treatment is at least one of deionized water and alcohol; (3) Carbonizing the pre-carbonized material at high temperature under an inert atmosphere to obtain hard carbon, wherein the inert atmosphere is at least one of nitrogen or argon.
2. The method for preparing a camphor seed-based porous hard carbon material according to claim 1, characterized in that: The drying temperature in step (1) is 80-100°C and the drying time is 24-48h.
3. The method for preparing a camphor seed-based porous hard carbon material according to claim 1, characterized in that: The hydrothermal temperature in step (2) is 160-200°C.
4. The method for preparing a camphor seed-based porous hard carbon material according to claim 1, characterized in that: The hydrothermal time in step (2) is 4-8h.
5. The method for preparing a camphor seed-based porous hard carbon material according to claim 1, characterized in that: The mass volume ratio of the raw material powder to the solvent in step (2) is 1 g:10-30 ml.
6. The method for preparing a camphor seed-based porous hard carbon material according to claim 1, characterized in that: The carbonization temperature in step (3) is 1000-1600°C, the holding time is 0.5-3h, and the heating rate is 1-10°C / min.
7. A camphor seed-based porous hard carbon material, characterized in that: Obtained according to the preparation method according to any one of claims 1 to 6.
8. An application of a camphor seed-based porous hard carbon material, characterized in that: The camphor tree seed-based porous hard carbon material according to claim 7 is used in the field of sodium ion batteries.