Ultrathin-wall fluffy interconnected porous carbon material as well as preparation method and application thereof
By using bitter nuts to prepare ultra-thin wall fluffy interconnected porous carbon materials, the complex problems existing in traditional lithium-sulfur battery cathode materials are solved, the electrochemical performance and cycle stability are improved, the production cost is reduced, and it is suitable for industrial production.
Patent Information
- Application Number
- CN202510402112.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2025-06-27
AI Technical Summary
There are complex problems in the positive electrode materials of traditional lithium-sulfur batteries, which limit the practical application of lithium-sulfur batteries, especially in terms of safety, energy density and production costs.
Using biomass bitter nuts with a wide range of sources as raw materials, ultra-thin wall fluffy interconnected porous carbon materials are prepared by freeze-drying and assisted carbonization method to increase the specific surface area, increase the load rate, and apply it to lithium-sulfur batteries.
It improves the electrochemical performance of the cathode material of lithium sulfur battery, enhances its cycle stability and energy density, reduces production costs, and is suitable for industrial production.
Smart Images
Figure CN120208199A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an ultra-thin wall fluffy interconnected porous carbon material, a preparation method thereof and an application thereof, belonging to the technical field of battery materials. Background Art
[0002] In recent years, with the rapid development of high-end electronic intelligent devices and new energy vehicles, people's demand for the long-cycle charge-discharge life and cycle stability during use of batteries has become increasingly high. In the last century, rechargeable batteries such as lead-acid batteries, nickel-cadmium batteries and lithium-ion batteries have been widely used. However, traditional LIBs have some limitations in terms of safety, energy density, production cost, etc., and can no longer meet the future market demand. LSB has received great attention due to its excellent theoretical energy density (2600 Wh / g), high theoretical specific capacity (1675 mAh / g), rich sulfur electrode reserves and cost-effectiveness. Nevertheless, a series of complex problems caused by the cathode material of lithium-sulfur batteries have hindered the practical application of LSB.
[0003] The rapid progress of technology and the sharp growth of human needs have led to the over-supply of traditional fossil fuels and other non-renewable resources. This imbalance has led to major environmental challenges. Therefore, it is urgent to seek new clean energy. All along, biomass has been considered a promising raw material for preparing functional materials due to its low cost, environmental friendliness, wide existence and easy availability. In addition to containing a large amount of carbon, hydrogen and oxygen elements, biomass is also rich in elements such as sulfur, nitrogen and phosphorus, and even contains metals such as iron and copper. Therefore, biomass has a good foundation as a raw material for lithium-sulfur batteries and has the potential to create significant economic value. At present, biomass materials that can be used to prepare porous carbon include pomelo peel, bamboo, coffee grounds, goat hair, citrus peel, chitosan, cotton paper, etc. Among them, there are many technical reports on using fruit shells as raw materials to obtain porous carbon by high-temperature carbonization. However, fruit shells are generally hard and dense, and the components contained are not easy to identify. The preparation process usually involves activation and pickling, and the loading rate is not high enough. For example, in the literature [Acta Electrochimica Sinica 420 (2022) 140454], Ren et al. prepared a porous carbon material using macadamia nut shells as a precursor. By studying the influence of temperature on the microstructure and electrochemical performance of the porous carbon material during the activation process, it was found that the composite cathode material prepared by loading 70.1% sulfur content on the porous carbon material prepared under the activation condition of 900 °C had the highest specific capacity, and the first discharge specific capacity at 0.2C was 942.4 mAh g -1 . The performance of the composite material obtained by compounding it with carbon nanotubes in a mass ratio of 1:1 was improved, and the process involved multiple operations such as activation and compounding. Summary of the Invention
[0004] The object of the present invention is to provide an ultrathin-walled fluffy interconnected porous carbon material, its preparation method and application. Using the widely sourced biomass of Castanopsis sclerophylla nuts as raw materials, an ultrathin-walled fluffy interconnected porous carbon material is prepared by a simple freeze-drying assisted carbonization method, which increases the specific surface area, improves the loading rate, and is applied to lithium-sulfur batteries.
[0005] To achieve the above object, the present invention provides the following technical solutions:
[0006] An ultrathin-walled fluffy interconnected porous carbon material is obtained by crushing nut kernels, mixing with a templating agent to form a slurry, pouring the slurry into a mold, drying to form a shape, and then subjecting the formed blank to high-temperature carbonization under a protective atmosphere. The high-temperature carbonization product is washed and dried.
[0007] Further preferably, metal ions or activators are also doped in the slurry.
[0008] A preparation method of an ultrathin-walled fluffy interconnected porous carbon material, which comprises crushing nut kernels, mixing with a templating agent to form a slurry, cooling and then pouring the slurry into a mold, drying to form a shape, and then subjecting the formed blank to high-temperature carbonization at 600 - 900 °C under the protection of an inert gas. The high-temperature carbonization product is washed and dried to obtain the ultrathin-walled fluffy interconnected porous carbon material.
[0009] Further preferably, the nut kernels can be crushed first and then mixed with the templating agent in proportion, or the nut kernels and the templating agent can be weighed in proportion first and then crushed. The slurry can be obtained by dry crushing followed by adding water and stirring, or by wet crushing with water.
[0010] Further preferably, metal ions or activators are added to the slurry, and after being fully dissolved, the slurry is poured into the mold to form a shape.
[0011] Further preferably, the drying and forming method is: freeze-drying in a freeze dryer.
[0012] Further preferably, the high-temperature carbonization process is: heating to 600 - 900 °C at a rate of 10 °C / min under a protective atmosphere and holding for 2 hours.
[0013] Further preferably, the high-temperature carbonization product is washed with hydrochloric acid and deionized water.
[0014] Further preferably, after washing, it is dried in an oven at 80 °C.
[0015] Further preferably, the templating agent includes one or more of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, and zinc chloride.
[0016] Further preferably, the metal ions include one or more of iron ions, cobalt ions, nickel ions, and manganese ions.
[0017] Further preferably, the activator includes one or more of sodium carbonate, sodium bicarbonate, and sodium hydroxide.
[0018] Further preferably, the mass ratio of the nut kernel to the template agent is 2:1 - 1:3.
[0019] Further preferably, the nut kernel and the template agent are added to a soymilk machine and ground into a slurry.
[0020] Further preferably, the addition amount of metal ions is 0.5% - 5% of the mass of the nut kernel; the addition amount of the activator is 2% - 8% of the mass of the nut kernel.
[0021] Further preferably, the nut kernel is a castanopsis sclerophylla nut kernel.
[0022] The present invention also provides an application of the ultrathin - walled fluffy interconnected porous carbon material in the preparation of a cathode material for a lithium - sulfur battery.
[0023] The present invention uses nut kernels with a wide source as a carbon source, and through a simple freeze - drying assisted high - temperature carbonization process, an ultrathin - walled fluffy interconnected porous carbon material is prepared. The process flow is simple, the required carbon source is simple and easy to obtain, there is no need to add a variety of raw materials, and the reagents involved in the reaction have little harm to the environment. It has strong replicability and is suitable for industrial production. At the same time, the material obtained by the present invention has excellent electrochemical performance when applied to lithium - sulfur batteries, injecting new impetus into the new energy cause. Description of the Drawings
[0024] Figure 1 Scanning electron microscope image of the ultrathin - walled fluffy interconnected porous carbon material prepared in Example 1:
[0025] Figure 2 Transmission electron microscope image of the ultrathin - walled fluffy interconnected porous carbon material prepared in Example 1;
[0026] Figure 3 X - ray diffraction pattern of the ultrathin - walled fluffy interconnected porous carbon material prepared in Example 1;
[0027] Figure 4 Nitrogen adsorption - desorption curve of the ultrathin - walled fluffy interconnected porous carbon material prepared in Example 1;
[0028] Figure 5 Discharge test result at 0.1C of the battery prepared with the ultrathin - walled fluffy interconnected porous carbon material as the cathode of the battery material in Example 1;
[0029] Figure 6 Comparison chart of the cycle life curves of the battery prepared in Example 2 at a current density of 0.1C;
[0030] Figure 7Cycling life curve of the battery fabricated using Example 3 at a current density of 0.2C;
[0031] Figure 8 Discharge test results of the battery fabricated using Example 4 at different current densities such as 0.1C, 0.2C, 0.5C, 1C, 2C;
[0032] Figure 9 Cycling life curve of the battery fabricated using Example 5 at a current density of 0.2C. Detailed implementation manners
[0033] The present invention will be further elaborated in detail below in conjunction with examples.
[0034] Example 1
[0035] (1) Take Castanopsis sclerophylla nuts (fresh, not dried), shell them, weigh 5 g of kernels and mix with 10 g of sodium chloride (sodium chloride as a template agent), add to a beaker and pour in 150 mL of deionized water; pour into a soymilk machine and blend into a slurry in the pulping mode. After it naturally cools to room temperature, pour it into a polystyrene mold and freeze-dry for 24 hours to obtain a precursor;
[0036] (2) Transfer the freeze-dried precursor to a ceramic crucible, under an argon atmosphere, heat it to 800 °C at a rate of 10 °C / min and hold for 2 hours; rinse the carbonized sample several times with deionized water until neutral, and finally dry it in an oven at 80 °C for 12 hours to obtain an ultrathin-walled fluffy interconnected porous carbon material (UIPC).
[0037] Comparative Example 1
[0038] As a comparison, different from Example 1, no template agent is added to obtain a raw porous carbon material (PC).
[0039] Figure 1 Scanning electron microscope images of the ultrathin-walled fluffy interconnected porous carbon and the raw porous carbon material. As can be seen from Figure 1 (b) therein, the surface of the porous carbon material generated without adding any template agent is agglomerated, with few pores and only sporadic large pores. On the contrary, Figure 1 (a) therein has a very rich pore structure, ultrathin pore walls, and no collapse, which gives the material an excellent specific surface area and can promote the dispersion of sulfur. Combining Figure 2 , it can be seen from the transmission electron microscope that the carbon material has extremely thin pore walls, and some short and broken carbon layers are observed at the edges, indicating that the material is amorphous in nature and the large pores are three-dimensionally interconnected, which can reduce the charge transport resistance.
[0040] Figure 3 X-ray diffraction pattern of the fabricated ultrathin-walled fluffy interconnected porous carbon material. From Figure 3As can be seen, only two broad peaks appear at approximately 22.8° and 44.0°, indicating the highly amorphous nature of the ultrathin-walled interconnected porous carbon material and the absence of excessive impurities.
[0041] Figure 4 Figure 4 shows the nitrogen adsorption-desorption isotherm and pore size distribution diagram of the ultrathin-walled interconnected porous carbon material, showing the hysteresis loop characteristics of type IV isotherms, indicating a micro / mesoporous structure. The specific surface area of this material is as high as 706.33 m 2 / g.
[0042] Synthesis of ultrathin-walled interconnected porous carbon-sulfur composite materials:
[0043] 20 mg of the ultrathin-walled interconnected porous carbon material obtained in Example 1 was thoroughly ground with 80 mg of sulfur, mixed evenly, and melt-impregnated at 155 °C for 12 hours to obtain a composite cathode material with a sulfur content of 80%.
[0044] As a comparison, a porous carbon material-sulfur composite material was prepared from the original porous carbon material obtained in Comparative Example 1.
[0045] Preparation of ultrathin-walled interconnected porous carbon-sulfur electrode materials: The ultrathin-walled interconnected porous carbon-sulfur composite material, acetylene black, and PVDF prepared above were mixed in a weight ratio of 8:1:1, with N-methylpyrrolidone as the dispersant. After thorough stirring to make the mixture uniform, it was rolled into a sheet and vacuum-dried at 60 °C for 10 hours for standby. The prepared ultrathin-walled interconnected porous carbon-sulfur electrode material was used as the positive electrode, metallic lithium as the negative electrode, and a Celgard 2400-type separator. The electrolyte was a mixed solution prepared by mixing anhydrous lithium nitrate with an additive of 0.1 mol / L, a solvent of 1,3-dioxolane and ethylene glycol dimethyl ether in a volume ratio of 1:1, and a 1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide solution. A lithium-sulfur battery was assembled in a glove box.
[0046] As a comparison, a battery of the original porous carbon material-sulfur composite material was assembled according to the above steps.
[0047] At a current density of 0.1 C, the charge-discharge cycle life test results are as Figure 5 shown. As can be seen from Figure 5 the ultrathin-walled interconnected porous carbon-sulfur electrode material has a discharge capacity of 611.7 mAh / g after 100 charge-discharge cycles. The original porous carbon electrode material without a templating agent has a discharge capacity of 365.9 mAh / g after 100 charge-discharge cycles. By comparison, after 100 charge-discharge cycles, the discharge capacity of the ultrathin-walled interconnected porous carbon-sulfur electrode material is 1.67 times that of the original porous carbon electrode material without a templating agent.
[0048] Example 2
[0049] (1) Shell the castanopsis sclerophylla nuts, weigh 5 g of kernels and mix them with 15 g of sodium chloride. Add them to a beaker and pour in 150 mL of deionized water. Pour the mixture into a soymilk maker and blend it into a slurry in the pulping mode. After it naturally cools to room temperature, pour it into a polystyrene mold and freeze-dry for 24 hours;
[0050] (2) Transfer the freeze-dried precursor to a ceramic crucible. Under an argon atmosphere, heat it to 800 °C at a rate of 10 °C / min and hold for 2 hours. Rinse the carbonized sample several times with deionized water until it is neutral, and finally dry it in an oven at 80 °C for 12 hours to obtain an ultrathin-walled fluffy interconnected porous carbon material.
[0051] Prepare an ultrathin-walled fluffy interconnected porous carbon-sulfur electrode material from the ultrathin-walled fluffy interconnected porous carbon material obtained in Example 2, assemble a lithium-sulfur battery, and test its performance.
[0052] From Figure 6 It can be seen from the comparison that whether it is the first time or after 100 charge-discharge cycles, the discharge capacity of the ultrathin-walled fluffy interconnected porous carbon-sulfur electrode material is higher than that of the original porous carbon electrode material without a templating agent.
[0053] Example 3
[0054] (1) Shell the castanopsis sclerophylla nuts, weigh 5 g of kernels and mix them with 15 g of sodium chloride. Add them to a beaker and pour in 140 mL of deionized water. Pour the mixture into a soymilk maker and blend it into a slurry in the pulping mode. After it naturally cools to room temperature, add 10 ml of a solution containing 180 mg of ferric nitrate, mix well, pour it into a polystyrene mold, and freeze-dry for 24 hours;
[0055] (2) Transfer the freeze-dried precursor to a ceramic crucible. Under an argon atmosphere, heat it to 800 °C at a rate of 10 °C / min and hold for 2 hours. Rinse the carbonized sample several times with deionized water until it is neutral, and finally dry it in an oven at 80 °C for 12 hours to obtain an iron-ion-doped ultrathin-walled fluffy interconnected porous carbon material (UIPC-F).
[0056] Prepare an iron-ion-doped ultrathin-walled fluffy interconnected porous carbon-sulfur electrode material from the iron-ion-doped ultrathin-walled fluffy interconnected porous carbon material obtained in Example 3, assemble a lithium-sulfur battery, and test its performance.
[0057] From Figure 7 It can be seen from the comparison that whether it is the first time or after 100 charge-discharge cycles, the discharge capacity of the iron-ion-doped ultrathin-walled fluffy interconnected porous carbon-sulfur electrode material is higher than that of the undoped ultrathin-walled fluffy interconnected porous carbon electrode material.
[0058] Among them, in Example 3, the present invention prepared ultrathin-walled fluffy interconnected porous carbon materials with Fe(NO3)3 doping amounts of 60 mg, 90 mg, 180 mg, and 360 mg respectively, all of which had good performance. For example, when the doping amount was 90 mg of Fe(NO3)3 and 80% sulfur was loaded, at a 0.2C condition, the initial capacity could reach 1132.5 mAh / g. After 100 cycles, there was still 609.4 mAh / g, and the performance was superior to that of the ultrathin-walled fluffy interconnected porous carbon material without Fe(NO3)3 doping.
[0059] Example 4
[0060] (1) Take the shelled Castanopsis sclerophylla nuts, weigh 5 g of kernels and mix them with 10 g of sodium chloride, add them to a beaker and inject 150 mL of deionized water; pour them into a soymilk machine and stir them into a slurry in the pulping mode. After naturally cooling to room temperature, add 250 mg of sodium bicarbonate; after mixing evenly, pour them into a polystyrene mold and freeze-dry for 24 hours;
[0061] (2) Transfer the freeze-dried precursor to a ceramic crucible. Under an argon atmosphere, heat it to 800 °C at a rate of 10 °C / min and hold for 2 hours; the obtained product is pickled with a hydrochloric acid solution with a mass concentration of 10%, and then washed with water until the pH value of the sample is neutral; finally, dry it in an oven at 80 °C for 12 hours to obtain a sodium-ion doped ultrathin-walled fluffy interconnected porous carbon material (UIPC-N).
[0062] Figure 8 The discharge test results of the battery made of the sodium-ion doped ultrathin-walled fluffy interconnected porous carbon material of Example 4 at different current densities such as 0.1C, 0.2C, 0.5C, 1C, and 2C.
[0063] Example 5
[0064] (1) Take the shelled Castanopsis sclerophylla nuts, weigh 5 g of kernels and mix them with 10 g of calcium chloride, add them to a beaker and inject 150 mL of deionized water; pour them into a soymilk machine and stir them into a slurry in the pulping mode. After naturally cooling to room temperature, pour them into a polystyrene mold and freeze-dry for 24 hours;
[0065] (2) Transfer the freeze-dried precursor to a ceramic crucible. Under an argon atmosphere, heat it to 800 °C at a rate of 10 °C / min and hold for 2 hours; rinse the carbonized sample with deionized water several times until it is neutral, and finally dry it in an oven at 80 °C for 12 hours to obtain an ultrathin-walled fluffy interconnected porous carbon material prepared with calcium chloride as a template agent.
[0066] Figure 9 The cycle life curve diagram of the battery made of the ultrathin-walled fluffy interconnected porous carbon material prepared with calcium chloride as a template agent of Example 5 at a 0.2C current density.
[0067] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.
Claims
1. An ultra-thin-walled, fluffy, interconnected porous carbon material, characterized in that: The nut kernels are crushed and mixed with a template agent to form a slurry, which is then poured into a mold and dried to form a slurry. The formed green body is then carbonized at high temperature under a protective atmosphere, and the high-temperature carbonized product is washed and dried.
2. The ultra-thin-walled fluffy interconnected porous carbon material according to claim 1, characterized in that: Metal ions or activators are also doped into the slurry.
3. A method for preparing an ultra-thin-walled, fluffy, interconnected porous carbon material, characterized in that: The nut kernels are crushed and mixed with a template agent to form a slurry, which is then poured into a mold after cooling and dried to form. The formed body is then carbonized at a high temperature of 600-900°C under the protection of an inert gas. The high-temperature carbonized product is washed and dried to obtain an ultra-thin-walled, fluffy, interconnected, porous carbon material.
4. The method for preparing the ultra-thin-walled fluffy interconnected porous carbon material according to claim 3, characterized in that: Add metal ions or activators to the slurry, fully dissolve it, and then pour it into the mold to form it.
5. The method for preparing the ultra-thin-walled fluffy interconnected porous carbon material according to claim 3, characterized in that: The drying and molding method is: freeze drying in a freeze dryer.
6. The method for preparing the ultra-thin-walled fluffy interconnected porous carbon material according to claim 3, characterized in that: The high temperature carbonization process is: heating to 600-900°C at 10°C / min under a protective atmosphere and keeping the temperature for 2 hours.
7. The method for preparing the ultra-thin-walled fluffy interconnected porous carbon material according to claim 3, characterized in that: The template includes one or more of sodium chloride, potassium chloride, calcium chloride, magnesium chloride and zinc chloride.
8. The method for preparing the ultra-thin-walled fluffy interconnected porous carbon material according to claim 3, characterized in that: The metal ions include one or more of iron ions, cobalt ions, nickel ions, and manganese ions; the activator includes one or more of sodium carbonate, sodium bicarbonate, and sodium hydroxide.
9. The method for preparing the ultra-thin-walled fluffy interconnected porous carbon material according to claim 3, characterized in that: The mass ratio of nut kernel to template agent is 2:1-1:3; the amount of metal ion added is 0.5%-5% of the mass of nut kernel; the amount of activator added is 2%-8% of the mass of nut kernel.
10. Use of the ultra-thin-walled fluffy interconnected porous carbon material according to claim 1 in preparing positive electrode materials for lithium-sulfur batteries.