Porous carbon as well as preparation method and application thereof
Porous carbon was prepared by using distiller's grains as raw material and employing a two-stage carbonization and alkaline etching method. This solved the problems of high cost and poor stability of porous carbon materials, and improved the electrochemical performance and lifespan of lithium-ion batteries.
Patent Information
- Application Number
- CN202511710513.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-20
- Publication Date
- 2026-01-16
AI Technical Summary
Existing porous carbon materials suffer from high costs, poor stability, and inconsistent raw material batches during preparation. Furthermore, silicon-based anode materials experience severe volume expansion during charge and discharge, which affects battery life.
Porous carbon was prepared using distiller's grains as raw material through a two-stage carbonization and alkaline etching process. The specific steps included first carbonization, crushing, second carbonization, and alkaline etching. Temperature and time were controlled to form micropores and mesopores, thereby improving the specific surface area and electrochemical stability.
This technology enables high-value recycling of porous carbon materials, reduces costs, improves electrochemical cycle stability and low volume expansion performance, and is suitable for use in the preparation of electrodes and batteries for lithium-ion batteries.
Smart Images
Figure CN121341998A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery materials technology, and more specifically, to a porous carbon, its preparation method, and its application. Background Technology
[0002] As the core power source for new energy vehicles, the lithium-ion battery industry continues its vigorous development. Currently, while graphite-based carbon materials dominate the market for power battery anode materials, their theoretical specific capacity is only 372 mAh / g, and they are prone to lithium dendrite formation during cycling, which has a certain impact on safety. This has driven research into novel anode materials, among which silicon materials have attracted attention due to their high theoretical capacity of 4200 mAh / g and abundant resource reserves. However, silicon materials have a major problem: they undergo significant volume expansion and contraction during charging and discharging, which greatly shortens battery life. Combining silicon and carbon materials to prepare silicon-carbon anode materials is an effective and efficient modification method to improve the cycle stability of silicon-based anodes, with porous carbon serving as a good substrate for silicon source deposition.
[0003] Currently, the raw materials for preparing porous carbon are divided into resin-based, pitch-based, and biomass-based. The advantages of resin-based materials are high purity and good consistency of raw materials, which can synthesize spherical porous carbon and help reduce the expansion rate. The disadvantage is that the cost is relatively high. The advantages of pitch-based materials are low cost of raw materials, wide availability of raw materials, and high carbonization rate. The disadvantage is that the impurity content is relatively high. The advantages of biomass carbon are wide availability of materials and low cost. The disadvantage is that the effect is affected by the raw materials and the batch stability is low.
[0004] Therefore, there is an urgent need to develop a porous carbon material that is highly stable, low in cost, and has readily available raw materials.
[0005] In view of this, the present invention is proposed. Summary of the Invention
[0006] The purpose of this invention is to provide porous carbon, its preparation method and application, in order to solve or improve the above-mentioned technical problems.
[0007] This invention can be implemented as follows: In a first aspect, the present invention provides a method for preparing porous carbon, comprising the following steps: The lees undergo a first carbonization, crushing, and a second carbonization, followed by alkaline washing and etching. The first carbonization is carried out at 100℃~2000℃ for 1h~24h; the second carbonization is carried out at 100℃~3000℃ for 1h~48h.
[0008] In an optional embodiment, the first carbonization is carried out at 200°C to 1500°C for 2 hours to 24 hours.
[0009] In an optional embodiment, the heating rate during the first carbonization process is 1°C / min to 20°C / min.
[0010] In an optional embodiment, the heating rate during the first carbonization process is 1°C / min to 10°C / min.
[0011] In an optional embodiment, the atmosphere for the first carbonization includes at least one of carbon dioxide, nitrogen, argon, helium, and a hydrogen-argon mixture.
[0012] In an optional embodiment, the second carbonization is carried out at 600°C to 2500°C for 2 to 12 hours.
[0013] In an optional embodiment, the heating rate during the second carbonization process is 1°C / min to 20°C / min.
[0014] In an optional embodiment, the heating rate during the second carbonization process is 5°C / min to 15°C / min.
[0015] In an optional embodiment, the atmosphere for the second carbonization includes at least one of carbon dioxide, nitrogen, argon, helium, and a hydrogen-argon mixture.
[0016] In an optional embodiment, the lees are pretreated and dried before the first carbonization. The drying temperature is 40℃~500℃, and the drying time is 1h~48h.
[0017] In an optional embodiment, the pretreatment drying atmosphere includes at least one of air, carbon dioxide, nitrogen, argon, helium, and a hydrogen-argon mixture.
[0018] In an optional implementation, after crushing, the particle size is adjusted to meet the requirement of D. 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 A second carbonization process is performed on crushed materials with a particle size of 18μm to 22μm.
[0019] In an optional implementation, ball milling is used for crushing.
[0020] In an optional embodiment, the ball milling time is 0.5h to 24h, preferably 0.5h to 10h.
[0021] In an optional embodiment, the ball mill speed is 200 r / min to 1000 r / min.
[0022] In an optional implementation, the ball-to-material ratio is 5:1 to 20:1 by mass.
[0023] In an optional embodiment, the diameter of the grinding balls used in the ball mill is 1 mm to 10 mm.
[0024] In an optional embodiment, alkaline etching includes at least one of the following features: Feature 1: The alkaline solution used for alkaline etching includes at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, and tetramethylammonium hydroxide solution; Feature 2: The ratio of the carbonized material obtained from the second carbonization to the alkaline solution used for alkaline etching is 4g:100mL to 12g:100mL; Feature 3: When the alkaline solution is at least one of sodium hydroxide solution, potassium hydroxide solution, and tetramethylammonium hydroxide solution, the concentration of the alkaline solution is 5wt%~70wt%; when the alkaline solution is ammonia, 100mL of alkaline solution contains 8%~12% ammonia. Feature 4: The alkaline etching time is 0.5h~48h; Feature 5: The temperature for alkaline etching is 20℃~100℃.
[0025] Secondly, the present invention provides a porous carbon, which is prepared by any of the preparation methods described in the foregoing embodiments.
[0026] In an optional embodiment, the porous carbon has at least one of the following characteristics: Feature 6: The specific surface area of porous carbon is not less than 1350 m². 2 / g; Feature 7: The D10 of porous carbon is 2 μm to 3.2 μm; Feature 8: The D50 of porous carbon is 4.5 μm to 6.0 μm; Feature 9: The D90 of porous carbon is 18.0 μm to 19.5 μm.
[0027] Thirdly, the present invention provides an electrode sheet, wherein the negative electrode active material of the electrode sheet includes porous carbon as described in the above embodiments.
[0028] Fourthly, the present invention provides a battery comprising the electrode sheets of the aforementioned embodiments.
[0029] The beneficial effects of this invention include: This invention provides a method for preparing porous carbon using distiller's grains as raw material, achieving high-value recycling of this material while being environmentally friendly. The distiller's grains used in this method have a significant cost advantage compared to other biomass carbon raw materials. In this method, the first carbonization primarily removes most of the volatile matter inside the distiller's grains, increasing the material's hardness to suit the second carbonization; it also provides initial pore-forming. Crushing increases the material's specific surface area and reactivity. The second carbonization ensures complete carbonization of the distiller's grains. Alkaline etching effectively removes the inherent silica within the distiller's grains, forming micropores and mesopores at the silica sites, further increasing the specific surface area of the porous carbon. The porous carbon material prepared by this method exhibits excellent electrochemical cycling stability and low volume expansion, and can be further used to prepare high-performance electrodes and batteries. Attached Figure Description
[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0031] Figure 1 This is a scanning electron microscope image of the porous carbon prepared in Example 1 of the present invention; Figure 2 This is a transmission electron microscope (TEM) image of the porous carbon prepared in Example 1 of the present invention. Figure 3 This is a scanning electron microscope image of the porous carbon prepared in Comparative Example 1 of the present invention. Figure 4 This is a scanning electron microscope image of the porous carbon prepared in Comparative Example 2 of the present invention. Figure 5 The graph shows the cycle stability test results of a lithium-ion battery made of porous carbon obtained in Example 1 of this invention. Figure 6 The graph shows the cycle stability test results of the lithium-ion battery made of porous carbon obtained in Example 2 of the present invention. Figure 7 The graph shows the rate performance test results of the lithium-ion battery made of porous carbon obtained in Example 3 of the present invention. Figure 8 The graph shows the cycle stability test results of the lithium-ion battery made of porous carbon prepared in Comparative Example 1 of this invention. Figure 9 The graph shows the cycle stability test results of the lithium-ion battery made of porous carbon obtained in Comparative Example 2 of this invention. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0033] The porous carbon, its preparation method, and its applications provided by this invention will be described in detail below.
[0034] This invention provides a method for preparing porous carbon, comprising the following steps: The lees undergo a first carbonization, crushing, and a second carbonization, followed by alkaline washing and etching. The first carbonization is carried out at 100℃~2000℃ for 1h~24h; the second carbonization is carried out at 100℃~3000℃ for 1h~48h.
[0035] In some alternative implementations, the temperature for the first carbonization can be 100°C, 200°C, 500°C, 800°C, 1000°C, 1200°C, 1500°C, 1800°C, or 2000°C, or other values within the range of 100°C to 2000°C. If the temperature for the first carbonization is too high, it can easily cause the material to collapse directly.
[0036] The time for the first carbonization can be 1h, 2h, 8h, 12h, 16h, 20h or 24h, or other values within the range of 1h to 24h.
[0037] In some preferred embodiments, the first carbonization can be carried out at 200°C to 1500°C for 2 hours to 24 hours.
[0038] In some optional embodiments, the heating rate during the first carbonization process can be from 1°C / min to 20°C / min, such as 1°C / min, 2°C / min, 5°C / min, 8°C / min, 10°C / min, 12°C / min, 15°C / min, 18°C / min, or 20°C / min, or other values within the range of 1°C / min to 20°C / min. In some preferred embodiments, the heating rate during the first carbonization process is from 1°C / min to 10°C / min.
[0039] In some alternative embodiments, the atmosphere for the initial carbonization may include at least one of carbon dioxide, nitrogen, argon, helium, and a mixture of hydrogen and argon.
[0040] As mentioned above, the first carbonization mainly removes most of the volatiles inside the lees, increases the hardness of the material, and makes it suitable for the second carbonization; in addition, it can also play a preliminary role in creating pores.
[0041] In some alternative embodiments, the temperature for the second carbonization can be 500°C, 800°C, 1000°C, 1200°C, 1500°C, 1800°C, 2000°C, 2200°C, 2500°C, 2800°C, or 3000°C, or other values within the range of 100°C to 3000°C.
[0042] If the temperature of the second carbonization exceeds 3000℃, it can easily cause the pores of the porous carbon material to collapse and close, reducing the porosity and thus reducing its electrochemical activity.
[0043] The second carbonization time can be 1 hour, 2 hours, 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, 28 hours, 32 hours, 36 hours, or 40 hours, or other values within the range of 1 hour to 48 hours. Preferably, the second carbonization time is longer than the first carbonization time.
[0044] In some preferred embodiments, the second carbonization can be carried out at 600°C to 2500°C for 2 to 12 hours.
[0045] In some optional embodiments, the heating rate during the second carbonization process can be from 1°C / min to 20°C / min, such as 1°C / min, 2°C / min, 5°C / min, 8°C / min, 10°C / min, 12°C / min, 15°C / min, 18°C / min, or 20°C / min, or other values within the range of 1°C / min to 20°C / min. In some preferred embodiments, the heating rate during the first carbonization process is from 5°C / min to 15°C / min.
[0046] In some alternative embodiments, the atmosphere for the second carbonization may include at least one of carbon dioxide, nitrogen, argon, helium, and a hydrogen-argon mixture.
[0047] In some alternative embodiments, in the Raman spectrum of the carbonized material obtained after the second carbonization, I d / I g The ratio is approximately 0.98.
[0048] Following on from the above, the second carbonization process can achieve graphitization, thus completely carbonizing the lees.
[0049] By performing a first carbonization and a second carbonization process sequentially, the collapse of the pore structure of the distiller's grains can be effectively prevented. However, if the distiller's grains are directly subjected to a second carbonization process, it will cause the distiller's grains to collapse and produce broken particles.
[0050] In some alternative implementations, the distiller's grains are pretreated and dried before the first carbonization. This process can be carried out, for example, in a tube furnace.
[0051] The drying temperature can be 40℃~500℃, such as 40℃, 50℃, 80℃, 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃ or 500℃, or other values within the range of 40℃~500℃.
[0052] The drying time can be from 1 hour to 48 hours, such as 1 hour, 8 hours, 16 hours, 24 hours, 32 hours, 40 hours or 48 hours, or other values within the range of 1 hour to 48 hours.
[0053] In some alternative embodiments, the pretreatment drying atmosphere may include at least one of air, carbon dioxide, nitrogen, argon, helium, and a hydrogen-argon mixture.
[0054] The above pretreatment drying process removes most of the moisture from the lees. After pretreatment drying, the lees are allowed to cool naturally to room temperature before the first carbonization.
[0055] In some alternative implementations, the particle size after crushing satisfies D 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 A second carbonization process is performed on crushed materials with a particle size of 18μm to 22μm.
[0056] Crushing can be exemplarily achieved through ball milling. Crushing can further increase the specific surface area and reactivity of the material.
[0057] The ball milling time can be from 0.5h to 24h, such as 0.5h, 1h, 2h, 4h, 8h, 12h, 16h, 20h, or 24h, or other values within the range of 0.5h to 24h. In some preferred embodiments, the ball milling time is from 0.5h to 10h.
[0058] The ball mill speed can be from 200 r / min to 1000 r / min, such as 200 r / min, 400 r / min, 600 r / min, 800 r / min or 1000 r / min, or other values within the range of 200 r / min to 1000 r / min.
[0059] The ball-to-material ratio, by weight, can be from 5:1 to 20:1, such as 5:1, 8:1, 10:1, 12:1, 15:1, 18:1, or 20:1, or other values within the range of 5:1 to 20:1. The diameter of the grinding balls used in the ball mill can be from 1 mm to 10 mm, for example, 1 mm, 3 mm, 5 mm, or 10 mm. In some specific embodiments, for example, 3 mm diameter zirconium beads and 5 mm diameter zirconium beads can be mixed at a weight ratio of 1:1 as grinding balls. In some optional embodiments, the alkaline solution used for alkaline etching may include at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia, and tetramethylammonium hydroxide solution.
[0060] The ratio of the carbonized material obtained from the second carbonization to the alkaline solution used for alkaline etching is 4g:100mL to 12g:100mL, such as 4g:100mL, 8g:100mL, 9g:100mL, 10g:100mL, 11g:100mL or 12g:100mL, etc., or other values within the range of 4g:100mL to 12g:100mL.
[0061] When the alkaline solution is at least one of sodium hydroxide solution, potassium hydroxide solution, and tetramethylammonium hydroxide solution, the concentration of the alkaline solution is 5wt% to 70wt%, such as 5wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, or 70wt%, etc., or other values within the range of 5wt% to 70wt%, preferably 10wt% to 50wt%. When the alkaline solution is ammonia water, 100mL of alkaline solution may contain 8% to 12% ammonia water.
[0062] The alkaline etching temperature can be between 20°C and 100°C, such as 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C, or other values within the range of 20°C to 100°C. In some preferred embodiments, the alkaline etching temperature is between 30°C and 90°C.
[0063] The alkaline etching time can be from 0.5h to 48h, such as 0.5h, 1h, 8h, 12h, 18h, 24h, 30h, 38h, 40h, or 48h, or other values within the range of 0.5h to 48h. In some preferred embodiments, the alkaline etching time is from 2h to 48h.
[0064] Alkaline etching can effectively remove the silica naturally present inside the lees, forming micropores and mesopores where the silica is located, further increasing the specific surface area of porous carbon.
[0065] As mentioned above, the method for preparing porous carbon provided by this invention uses distiller's grains as raw material, realizing the high-value recycling of distiller's grains material, and is environmentally friendly; the distiller's grains used in this method have a significant cost advantage compared with other biomass carbon raw materials; furthermore, the porous carbon material prepared in this invention has good electrochemical cycle stability and low volume expansion performance.
[0066] Accordingly, the present invention also provides a porous carbon, which is prepared by the above-described preparation method.
[0067] In some optional embodiments, the specific surface area of the porous carbon is not less than 1350 m². 2 / g, for example, the specific surface area of porous carbon can be 1350m². 2 / g~1651m 2 / g.
[0068] In some alternative embodiments, the D10 of the porous carbon is 2 μm to 3.2 μm, for example 2.1 μm to 3.1 μm.
[0069] In some alternative embodiments, the D50 of the porous carbon is 4.5 μm to 6.0 μm, for example 4.6 μm to 5.8 μm.
[0070] In some alternative embodiments, the D90 of the porous carbon is 18.0 μm to 19.5 μm, for example, 18.0 μm to 19.3 μm.
[0071] In some alternative embodiments, such as Example 1, the porous carbon has an average pore size of 2.34 nm; in Example 2, the porous carbon has an average pore size of 2.69 nm. Furthermore, the present invention also provides an electrode whose negative electrode active material comprises the aforementioned porous carbon.
[0072] Furthermore, the present invention also provides a battery comprising the aforementioned electrode plates.
[0073] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0074] Example 1 This embodiment provides a porous carbon (distillery lees-derived porous carbon), the preparation method of which includes: S1: Place 50g of distiller's grains in a tube furnace and heat to 300℃ under an argon atmosphere at a heating rate of 5℃ / min. Hold at this temperature for 2 hours for pretreatment and drying. After the distiller's grains have cooled naturally, remove them from the tube furnace.
[0075] S2: After cooling, put the lees back into the tube furnace and heat it to 600°C in an argon atmosphere at a heating rate of 5°C / min. Hold it at this temperature for 2 hours for the first carbonization. After the lees have cooled naturally, remove them from the tube furnace.
[0076] S3: The lees after the first carbonization are ball-milled for 2 hours at a speed of 400 r / min, using 5 mm diameter zirconium balls at a ball-to-material ratio of 10:1. The crushed lees are then sieved through a screen to collect particles that meet the D... 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0077] S4: Place the collected crushed material into a tube furnace and heat it to 1200℃ in an argon atmosphere at a heating rate of 10℃ / min. Hold the temperature for 6 hours for a second carbonization. After the distiller's grains material has cooled naturally, remove it from the tube furnace.
[0078] S5: Prepare a 20% sodium hydroxide solution, put 10g of the carbonized material after the second carbonization into 250ml of the above sodium hydroxide solution, stir and etch at 60℃ for 2h. After etching, wash with pure water, and then put it into a 70℃ oven for drying, finally obtaining the porous carbon material derived from the lees.
[0079] Example 2 This embodiment provides a porous carbon (distillery lees-derived porous carbon), the preparation method of which includes: S1: Place 50g of distiller's grains in a tube furnace and heat to 150℃ under a nitrogen atmosphere at a heating rate of 2℃ / min. Hold at this temperature for 2 hours for pretreatment and drying. After the distiller's grains have cooled naturally, remove them from the tube furnace.
[0080] S2: After cooling, the lees are put back into the tube furnace and heated to 800°C in a nitrogen atmosphere at a heating rate of 5°C / min. The mixture is held at this temperature for 2 hours for the first carbonization. After the lees have cooled naturally, they are taken out of the tube furnace.
[0081] S3: The lees after the first carbonization are ball-milled for 2 hours at a speed of 600 r / min, using 5 mm diameter zirconium balls at a ball-to-material ratio of 10:1. The crushed lees are then sieved through a screen to collect particles that meet the D... 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0082] S4: Place the collected crushed material into a tube furnace and heat it to 1300℃ in a nitrogen atmosphere at a heating rate of 10℃ / min. Hold the temperature for 12 hours for a second carbonization. After the distiller's grains material has cooled naturally, remove it from the tube furnace.
[0083] S5: Prepare a 20% sodium hydroxide solution, put 10g of the carbonized material after the second carbonization into 250ml of the above sodium hydroxide solution, stir and etch at 60℃ for 4h. After etching, wash with pure water, and then put it into a 70℃ oven for drying, and finally obtain the porous carbon material derived from the lees.
[0084] Example 3 This embodiment provides a porous carbon (distillery lees-derived porous carbon), the preparation method of which includes: S1: Place 50g of distiller's grains in a tube furnace and heat to 500℃ under an argon atmosphere at a heating rate of 5℃ / min. Hold at this temperature for 2 hours for pretreatment and drying. After the distiller's grains have cooled naturally, remove them from the tube furnace.
[0085] S2: After cooling, the lees are put back into the tube furnace and heated to 1000°C in an argon atmosphere at a heating rate of 10°C / min. The mixture is held at this temperature for 4 hours for the first carbonization. After the lees have cooled naturally, they are taken out of the tube furnace.
[0086] S3: The lees after the first carbonization are ball-milled for 2 hours at a speed of 600 r / min, using 5 mm diameter zirconium balls at a ball-to-material ratio of 10:1. The crushed lees are then sieved through a screen to collect particles that meet the D... 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0087] S4: Place the collected crushed material into a tube furnace and heat it to 1500℃ in an argon atmosphere at a heating rate of 10℃ / min. Hold the temperature for 6 hours for a second carbonization. After the distiller's grains material has cooled naturally, remove it from the tube furnace.
[0088] S5: Prepare a 20% KOH solution, put 10g of the carbonized material after the second carbonization into 250ml of the above KOH solution, stir and etch at 60℃ for 2h. After etching, wash with pure water, and then put it into a 70℃ oven for drying. Finally, the porous carbon material derived from the lees is obtained.
[0089] Example 4 This embodiment provides a porous carbon (distillery lees-derived porous carbon), the preparation method of which includes: S1: Place 50g of distiller's grains in a tube furnace and heat to 120℃ under a nitrogen atmosphere at a heating rate of 5℃ / min. Hold at this temperature for 12 hours for pretreatment and drying. After the distiller's grains have cooled naturally, remove them from the tube furnace.
[0090] S2: After cooling, put the lees back into the tube furnace and heat it to 700°C in a carbon dioxide atmosphere at a heating rate of 10°C / min. Hold the temperature for 4 hours for the first carbonization. After the lees have cooled naturally, remove them from the tube furnace.
[0091] S3: The lees after the first carbonization are ball-milled for 4 hours at a speed of 500 rpm. Zirconium balls with a diameter of 3 mm are used, and the ball-to-material ratio is 10:1. The crushed lees are then sieved through a screen to collect particles meeting the specified particle size D. 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0092] S4: Place the collected crushed material into a tube furnace and heat it to 2000℃ in an argon atmosphere at a heating rate of 10℃ / min. Hold the temperature for 2 hours for a second carbonization. After the distiller's grains material has cooled naturally, remove it from the tube furnace.
[0093] S5: Prepare an alkaline solution with a concentration of 50% KOH:NaOH = 3:1. Place 10g of the carbonized material after the second carbonization into 250ml of the above alkaline solution and stir and etch at 90℃ for 12h. After etching, wash with pure water and then dry in a 70℃ oven to obtain the porous carbon material derived from the lees.
[0094] Example 5 This embodiment provides a porous carbon (distillery lees-derived porous carbon), the preparation method of which includes: S1: Place 50g of distiller's grains in a tube furnace and heat to 80℃ in an air atmosphere at a heating rate of 5℃ / min. Hold at this temperature for 24 hours for pretreatment and drying. After the distiller's grains have cooled naturally, remove them from the tube furnace.
[0095] S2: After cooling, the lees are put back into the tube furnace and heated to 500°C in a nitrogen atmosphere at a heating rate of 2°C / min. The mixture is held at this temperature for 4 hours for the first carbonization. After the lees have cooled naturally, they are taken out of the tube furnace.
[0096] S3: The lees after the first carbonization are ball-milled for 10 hours at a speed of 200 r / min, using 10 mm diameter zirconium balls at a ball-to-material ratio of 10:1. The crushed lees are then sieved through a screen to collect particles that meet the D... 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0097] S4: Place the collected crushed material into a tube furnace and heat it to 900℃ in a nitrogen atmosphere at a heating rate of 10℃ / min. Hold it at this temperature for 6 hours for a second carbonization. After the distiller's grains material has cooled naturally, remove it from the tube furnace.
[0098] S5: Prepare a 30% KOH solution, put 10g of the carbonized material after the second carbonization into 250ml of the above KOH solution, stir and etch at 60℃ for 6h, wash with pure water after etching, and then put it into a 70℃ oven for drying, finally obtaining the lees-derived porous carbon material.
[0099] Example 6 This embodiment provides a porous carbon (distillery lees-derived porous carbon), the preparation method of which includes: S1: Place 50g of distiller's grains in a tube furnace and heat to 300℃ in a carbon dioxide atmosphere at a heating rate of 10℃ / min. Hold at this temperature for 6 hours for pretreatment and drying. After the distiller's grains have cooled naturally, remove them from the tube furnace.
[0100] S2: After cooling, the lees are put back into the tube furnace and heated to 400°C in a carbon dioxide atmosphere at a heating rate of 1°C / min. The mixture is held at this temperature for 24 hours for the first carbonization. After the lees have cooled naturally, they are taken out of the tube furnace.
[0101] S3: The lees after the first carbonization are ball-milled for 1 hour at a speed of 700 rpm. Zirconium balls with a diameter of 5 mm are used, and the ball-to-material ratio is 10:1. The crushed lees are then sieved through a screen to collect particles that meet the D... 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0102] S4: Place the collected crushed material into a tube furnace and heat it to 600℃ in an argon atmosphere at a heating rate of 5℃ / min. Hold the temperature for 12 hours for a second carbonization. After the distiller's grains material has cooled naturally, remove it from the tube furnace.
[0103] S5: Prepare a 40% sodium hydroxide solution, put 10g of the carbonized material after the second carbonization into 250ml of the above sodium hydroxide solution, stir and etch at 80℃ for 8h. After etching, wash with pure water, then put it into a 70℃ oven for drying, and finally obtain the porous carbon material derived from the lees.
[0104] Example 7 This embodiment provides a porous carbon (distillery lees-derived porous carbon), the preparation method of which includes: S1: Place 50g of distiller's grains in a tube furnace and heat to 500℃ under an argon atmosphere at a heating rate of 10℃ / min. Hold at this temperature for 2 hours for pretreatment and drying. After the distiller's grains have cooled naturally, remove them from the tube furnace.
[0105] S2: After cooling, the lees are put back into the tube furnace and heated to 1500°C in a hydrogen-argon mixed atmosphere at a heating rate of 10°C / min. The mixture is held at this temperature for 2 hours for the first carbonization. After the lees have cooled naturally, they are taken out of the tube furnace.
[0106] S3: The lees after the first carbonization are ball-milled for 0.5 hours at a speed of 1000 rpm, using 1 mm diameter zirconium balls at a ball-to-material ratio of 10:1. The crushed lees are then sieved through a screen to collect particles that meet the D... 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0107] S4: Place the collected crushed material into a tube furnace and heat it to 2500℃ in an argon atmosphere at a heating rate of 15℃ / min. Hold the temperature for 2 hours for a second carbonization. After the distiller's grains material has cooled naturally, remove it from the tube furnace.
[0108] S5: Prepare a 20% sodium hydroxide solution, put 10g of the carbonized material after the second carbonization into 250ml of the above sodium hydroxide solution, stir and etch at 80℃ for 24h. After etching, wash with pure water, and then put it into a 70℃ oven for drying, finally obtaining the porous carbon material derived from the lees.
[0109] Example 8 This embodiment provides a porous carbon (distillery lees-derived porous carbon), the preparation method of which includes: S1: Place 50g of distiller's grains in a tube furnace and heat to 40℃ under a nitrogen atmosphere at a heating rate of 5℃ / min. Hold at this temperature for 48 hours for pretreatment and drying. After the distiller's grains have cooled naturally, remove them from the tube furnace.
[0110] S2: After cooling, the lees are put back into the tube furnace and heated to 200°C in a nitrogen atmosphere at a heating rate of 1°C / min. The mixture is held at this temperature for 24 hours for the first carbonization. After the lees have cooled naturally, they are taken out of the tube furnace.
[0111] S3: The lees after the first carbonization are ball-milled for 4 hours at a speed of 700 r / min, using 5 mm diameter zirconium balls at a ball-to-material ratio of 10:1. The crushed lees are then sieved through a screen to collect particles that meet the D... 10 The diameter is 1μm~3μm, D 504μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0112] S4: Place the collected crushed material into a tube furnace and heat it to 1200℃ in an argon atmosphere at a heating rate of 5℃ / min. Hold it at this temperature for 8 hours for a second carbonization. After the distiller's grains material has cooled naturally, remove it from the tube furnace.
[0113] S5: Prepare an alkaline solution containing 10wt% ammonia. Place 10g of the carbonized material after the second carbonization into 250ml of the above alkaline solution and stir and etch at 30℃ for 48h. After etching, wash with pure water and then dry in a 70℃ oven to obtain the porous carbon material derived from distillers' grains.
[0114] Comparative Example 1 The difference between this comparative example and Example 1 is that the alkaline etching step S5 was not performed.
[0115] Comparative Example 2 This comparative example provides a porous carbon material derived from distiller's grains (i.e., a one-step calcination etching comparison sample), the preparation method of which includes the following steps: S1: Heat 50g of distiller's grains directly in a tube furnace under an argon atmosphere to 1200℃ at a heating rate of 10℃ / min, and hold for 6 hours for high-temperature carbonization. After the distiller's grains material cools naturally, remove it from the tube furnace.
[0116] S2: The high-temperature carbonized distiller's grains are ball-milled for 2 hours at a speed of 400 r / min, using 5 mm diameter zirconium balls at a ball-to-material ratio of 10:1. The crushed distiller's grains are then sieved through a screen to collect particles that meet the D... 10 The diameter is 1μm~3μm, D 50 4μm~6μm, D 90 The material is crushed to a size of 18μm~22μm.
[0117] S3: Prepare a 20% sodium hydroxide solution, put 10g of crushed material into 250ml of the above sodium hydroxide solution, stir and etch at 60℃ for 2h. After etching, wash with pure water, then put it into a 70℃ oven for drying, and finally obtain the distillers' grains-derived porous carbon material.
[0118] Comparative Example 3 The difference between this comparative example and Example 1 is that no crushing was performed between the first and second carbonization processes.
[0119] Comparative Example 4 The difference between this comparative example and Example 1 is that the carbonization process was maintained at 1200°C for 8 hours.
[0120] Comparative Example 5 The difference between this comparative example and Example 1 is that the temperature of the second carbonization is 3200°C.
[0121] Test case (1) The porous carbon prepared in Example 1 was subjected to scanning electron microscopy and transmission electron microscopy tests, and the results are as follows: Figure 1 and Figure 2 As shown. By Figure 1 and Figure 2 It can be seen that the porous carbon prepared in this embodiment has a large number of uniformly distributed pores on its surface, and micropores can also be seen inside the lees through transmission electron microscopy.
[0122] The porous carbon prepared in Comparative Example 1 was subjected to scanning electron microscopy (SEM) analysis, and the results are as follows: Figure 3 As shown. Compared to Example 1, no obvious pores appeared on the surface of the unetched lees.
[0123] The porous carbon prepared in Comparative Example 2 was subjected to scanning electron microscopy (SEM) analysis, and the results are as follows: Figure 4 As shown. Compared to Example 1, the pore structure of the material etched by one-step calcination collapsed, proving that the carbon material calcined at low temperature has a more stable structure.
[0124] (2) The specific surface area and particle size of the porous carbon prepared in Examples 1-8 and Comparative Examples 1-5 were compared, and the results are shown in Table 1.
[0125] The specific surface area was tested in accordance with GB / T 19587-2017; the particle size was tested using the Topsizer laser particle size analyzer.
[0126] Table 1 Test Results
[0127] As can be seen from Examples 1 to 8 in Table 1, porous carbon with different specific surface areas can be obtained according to different preparation process conditions.
[0128] A comparison of each embodiment with Comparative Example 1 shows that the porous carbon material made from distiller's grains after alkali washing has a significant improvement over the comparative example.
[0129] A comparison between Example 1 and Comparative Example 2 shows that although the specific surface area of Comparative Example 2 is increased, it is mainly due to the material collapsing and forming fragments.
[0130] (3) Constant current charge-discharge tests were conducted on the porous carbon prepared in Examples 1-8 and Comparative Examples 1-5. The porous carbon was homogenized with CMC and Super P in a ratio of 8:1:1. The resulting slurry was coated onto copper foil using a coating tool. After drying, the electrode was formed into a disc with a diameter of 1.2 cm. A lithium metal sheet was used as the counter electrode, and 1 mol / L LiPF6 dissolved in DMC:EC:EMC = 1:1:1 was used as the electrolyte. The electrode sheets were assembled into an R2032 coin cell for testing. The test current density was 0.2 A / g. The test results are shown in Table 2 and... Figure 5 (Corresponding to Example 1) Figure 6 (Corresponding to Example 2) and Figure 8 (Response ratio 1) and Figure 9 (As shown in Example 2). Furthermore, Example 3 also tested the discharge specific capacity and capacity retention rate under test current densities of 0.1 A / g, 0.33 A / g, 1 A / g, and 2 A / g, and the results are shown in Table 3 and... Figure 7 As shown.
[0131] Table 2 Test Results
[0132] Table 3 Test Results
[0133] As can be seen from Tables 2 and 3, the porous carbon of the embodiments of the present invention can be further used to prepare lithium-ion batteries with better electrochemical performance.
[0134] In summary, the method provided by this invention is green, environmentally friendly, low-cost, and easy to industrialize. The porous carbon prepared by this method has a high specific surface area, good electrochemical cycle stability, and low volume expansion performance, and can be further used to prepare high-performance electrodes and batteries.
[0135] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for producing a porous carbon, characterized by, The method comprises the following steps: The distiller's grains are subjected to a first carbonization, a crushing, and a second carbonization, followed by an alkali etching; The first carbonization is performed at 100-2000℃ for 1-24h, and the second carbonization is performed at 100-3000℃ for 1-48h.
2. The production method according to claim 1, characterized by, The first carbonization is performed at 200-1500℃ for 2-24h. Preferably, the heating rate during the first carbonization is 1-20℃ / min. Preferably, the heating rate during the first carbonization is 1-10℃ / min. Preferably, the atmosphere during the first carbonization comprises at least one of carbon dioxide, nitrogen, argon, helium, and hydrogen-argon mixture.
3. The production method according to claim 1, characterized by, The second carbonization is performed at 600-2500℃ for 2-12h. Preferably, the heating rate during the second carbonization is 1-20℃ / min. Preferably, the heating rate during the second carbonization is 5-15℃ / min. Preferably, the atmosphere during the second carbonization comprises at least one of carbon dioxide, nitrogen, argon, helium, and hydrogen-argon mixture.
4. The preparation method according to any one of claims 1 to 3, characterized in that, Before the first carbonization, the distiller's grains are also subjected to a pre-treatment drying; The drying temperature is 40-500℃, and the drying time is 1-48h. Preferably, the atmosphere during the pre-treatment drying comprises at least one of air, carbon dioxide, nitrogen, argon, helium, and hydrogen-argon mixture.
5. The preparation method according to any one of claims 1 to 3, characterized in that, After crushing, the crushed material with particle size D 10 1 μm to 3 μm, D 50 4 μm to 6 μm, D 90 18 μm to 22 μm is subjected to second carbonization. Preferably, the crushing is performed by ball milling. Preferably, the ball milling time is 0.5-24h, preferably 0.5-10h. Preferably, the ball milling speed is 200-1000r / min. Preferably, the ball-to-material ratio is 5:1 to 20:1 by mass. Preferably, the diameter of the milling balls is 1-10mm.
6. The preparation method according to any one of claims 1 to 3, characterized in that, The alkali etching comprises at least one of the following features: Feature 1: The alkali solution used in the alkali etching comprises at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, and tetramethylammonium hydroxide solution. Feature 2: The ratio of the carbonized material obtained from the second carbonization to the alkali solution used in the alkali etching is 4g:100mL to 12g:100mL. Feature 3: When the alkali solution is at least one of sodium hydroxide solution, potassium hydroxide solution, and tetramethylammonium hydroxide solution, the concentration of the alkali solution is 5-70wt%; when the alkali solution is ammonia water, 100mL of the alkali solution contains 8-12% ammonia water. Feature 4: The time for the alkali etching is 0.5-48h. Feature 5: The temperature for the alkali etching is 20-100℃.
7. A porous carbon, characterized by, Prepared by the preparation method of any one of claims 1-6.
8. The porous carbon according to claim 7, characterized in that, The porous carbon has at least one of the following features: Feature 6: The specific surface area of the porous carbon is not less than 1350 m 2 / g; Feature 7: The D10 of the porous carbon is 2-3.2μm. Feature 8: The D50 of the porous carbon is 4.5-6.0μm. Feature 9: The D90 of the porous carbon is 18.0-19.5μm.
9. A pole piece characterized by, The negative active material of the electrode sheet comprises the porous carbon of claim 7 or 8.
10. A battery, characterized by The battery contains the electrode sheet of claim 9.