Graphite-like capacitive carbon, and preparation method and application thereof

Abstract

The application relates to a kind of graphite-like capacitor carbon and its preparation method and application, relate to carbon material technical field, solve the problem that the needle coke-based capacitor carbon in the activation pore-forming process of prior art is difficult to consider high specific surface area, layered ordered graphite structure keeps, pore size structure uniform control and continuous electric conduction network, leading to the specific capacitance, rate performance and cycle stability of material are limited.The application is by mixing needle coke powder and chemical activator, first activation is carried out by heating, and the activated product is obtained, and the intermediate product A is obtained by post-processing;Intermediate product A is mixed with catalytic activator, second activation is carried out by heating, and catalytic graphitization product is obtained, and the intermediate product B is obtained by post-processing;The intermediate product B is calcined to obtain graphite-like capacitor carbon by refining treatment.The graphite-like capacitor carbon provided by the application can be applied to the preparation of supercapacitors, and the synergistic balance between high specific surface area, high packing density, excellent conductivity and structural stability is realized.

Description

Technical Field

[0001] This invention relates to the field of carbon materials technology, specifically to a graphite-like capacitor carbon, its preparation method, and its application. Background Technology

[0002] Supercapacitors, as a novel type of energy storage device situated between traditional capacitors and secondary batteries, possess characteristics such as high power density, fast charge / discharge speed, long cycle life, and excellent low-temperature performance, demonstrating broad application prospects in high-power instantaneous output and long-life energy storage. Electrode materials for supercapacitors mainly include activated carbon, graphene, carbon nanotubes, and porous carbon materials. Among these, activated carbon is widely used due to its wide availability and low cost. However, traditional activated carbon generally suffers from low graphitization, insufficient conductivity, disordered pore structure, and low volumetric capacity. Especially under high power density and high-rate charge / discharge conditions, it is prone to increased internal resistance, limited ion transport, and decreased cycle stability, making it difficult to meet the development requirements of high-end energy storage devices. Therefore, high-performance capacitor carbon materials possessing both graphite-like ordered structures and abundant pore structures are gradually attracting attention.

[0003] Needle coke, as a high-end carbon precursor material, can form a highly oriented layered graphite structure during high-temperature calcination, exhibiting advantages such as high crystallinity, high conductivity, low coefficient of thermal expansion, and low ash content. Especially under calcination conditions of 1300–1400℃, needle coke forms a relatively complete layered ordered structure, exhibiting significantly superior electron transport capabilities compared to ordinary amorphous carbon materials, which is beneficial for reducing the internal resistance of supercapacitors and improving cycle life. However, needle coke itself is characterized by high graphitization, small interlayer spacing, and dense structure. While its highly ordered graphite microcrystalline structure endows the material with excellent conductivity, it also significantly increases the difficulty of activation and pore formation. Current technologies typically employ chemical activators such as KOH for a single high-temperature activation treatment of needle coke to improve the material's specific surface area and energy storage performance. However, due to the dense structure of needle coke, the activator cannot fully penetrate the graphite layers, resulting in a limited number of pores and restricted specific surface area improvement. This limits the provision of sufficient charge adsorption sites, leading to a lower specific capacitance in the assembled supercapacitor, which fails to meet the application requirements of high-performance energy storage devices.

[0004] To further improve porosity, existing technologies typically employ methods such as increasing the alkali-to-carbon ratio, raising the activation temperature, or extending the activation time to enhance the activation degree of the activator, thereby promoting the formation of more porous structures within the needle coke. However, these methods often fail to adequately consider the synergistic balance between maintaining the layered ordered structure, controlling the pore size gradient, and ensuring the continuity of the conductive network. At low activation levels, the number of pores in the material is limited, making it difficult to achieve a high specific capacitance. Conversely, excessive activation can easily lead to over-etching of the graphite skeleton, resulting in decreased conductivity and reduced structural stability. Because needle coke itself possesses a high degree of graphitization and a dense layered structure, the enhanced activation process can easily cause localized over-etching of the carbon skeleton, resulting in a lack of uniformity and continuity in the formed pore structure. This limits the control of pore size distribution and makes it difficult to balance the synergistic relationship between micropore energy storage and ion transport, thus affecting the material's volumetric filling density and rate performance. Meanwhile, traditional single-stage chemical activation processes can easily disrupt the original layered ordered graphite structure of needle coke during pore formation, leading to an increase in graphite microcrystal defects. This, in turn, affects the material's electron transport performance and cycle stability, making it difficult to achieve a synergistic balance of high specific surface area, high conductivity, and low internal resistance. For example, Chinese invention patent CN111029167A discloses a method for preparing needle coke-based electrode materials using KOH activation combined with hydrothermal control of the pore structure using transition metals. Although this technology can improve the material's porosity and specific capacitance, its technical route still mainly relies on single-stage enhanced activation for pore formation. It has limited ability to maintain the layered ordered structure of needle coke and control the uniformity of the pore structure, easily leading to an increase in local framework defects and disordered pore structure. This makes it difficult for the material to simultaneously achieve a high graphitized conductive structure, high specific surface area, and low internal resistance, thus limiting its application under high-rate, large-ion systems, and high-energy-density conditions. Summary of the Invention

[0005] To address the limitations of existing needle-shaped coke-based capacitor carbons in achieving high specific surface area, maintaining a layered, ordered graphite structure, uniformly controlling pore size, and ensuring the continuity of the conductive network during the activation and pore-forming process, thus restricting the material's specific capacitance, rate performance, and cycle stability, this invention proposes a graphite-like capacitor carbon, its preparation method, and its applications. The technical solution of this invention is as follows: A method for preparing graphite-like capacitor carbon includes the following preparation steps: S1: Mix needle-shaped coke powder with an aqueous solution of chemical activator, stir, dry, and place in an activation furnace for the first activation to obtain an activated product. The activated product is then post-treated to obtain intermediate product A. S2: Mix intermediate product A with an aqueous solution of catalytic activator, dry, and place in an activation furnace for a second activation to obtain catalytic graphitization product. After post-treatment of the catalytic product, intermediate product B is obtained. S3: Grind intermediate product B and calcine it for refining to obtain graphite-like capacitor carbon.

[0006] Furthermore, the particle size of the needle coke powder in S1 is 25~50 μm, preferably 25 μm; the needle coke is any one or a combination of two of petroleum-based needle coke and coal-based needle coke.

[0007] Furthermore, the chemical activator is any one or a combination of two of potassium hydroxide and sodium hydroxide; the mass ratio of the needle-shaped coke powder to the chemical activator is 1:1.3~1.6, preferably 1:1.4.

[0008] Furthermore, the stirring is carried out until the mixture forms a ball; the drying temperature is 100~140℃ and the time is 100~140 min.

[0009] Furthermore, the first activation in S1 is carried out in an inert gas atmosphere; the temperature rise is to 740~780℃, preferably 740℃; the holding time is 120~180 min, preferably 150 min.

[0010] Further, the post-processing steps of the activated product in S1 include: washing and drying the activated product; the drying time is 120~140 min; and the drying temperature is 100~140℃.

[0011] Furthermore, the catalytic activator in S2 is any one or a combination of at least two of ferric chloride, zinc chloride, and nickel chloride; preferably ferric chloride.

[0012] Further, in S2, the mass ratio of intermediate product A to catalytic activator is 1:0.1 to 1:0.5, preferably 1:0.2; the drying temperature is 120 to 130°C, and the drying time is 110 to 130 min.

[0013] Furthermore, the second activation in S2 is carried out in an inert gas atmosphere; the temperature of the second activation is 800~850℃, preferably 820℃; the holding time of the second activation is 100~140 min, preferably 120 min; Furthermore, the post-processing steps of the catalytic graphitization product in S2 include: washing and drying the catalytic graphitization product; the washing includes acid washing and water washing; the drying time is 170~190 min and the temperature is 100~120℃.

[0014] Further, in step S3, the intermediate product B is ground to a particle size of D50 = 6~9 μm, preferably D50 = 7 μm; the calcination temperature is 730~760℃, preferably 760℃; the calcination time is 90~110 min, preferably 90 min; and the calcination atmosphere is nitrogen. The refining process involves placing the intermediate product B in a titanium-steel container and then calcining it in a high-temperature calcination furnace to obtain a high-density, graphite-like capacitor carbon with a large specific surface area.

[0015] Furthermore, the pore size of the graphite-like capacitor carbon is 0.7~2 nm; the particle size of the graphite-like capacitor carbon is D50=6~8 μm.

[0016] Furthermore, the inert gas is either nitrogen or argon, preferably nitrogen.

[0017] A graphite capacitor carbon was prepared by the above-described preparation method.

[0018] An application of a graphite-like capacitor carbon in the field of supercapacitors.

[0019] Compared with existing technologies, this invention solves the problem that existing needle-shaped coke-based capacitor carbons are difficult to balance in the activation and pore-forming process, resulting in limitations in material specific capacitance, rate performance, and cycle stability. The specific beneficial effects are as follows: 1. This invention employs a two-stage synergistic activation of needle coke using both chemical and catalytic activators. The first low-temperature chemical activation constructs an ultraporous structure within the needle coke, and the second catalytic graphitization process further widens and restructures these micropores, resulting in a pore structure system dominated by 0.7–2 nm micropores, thus achieving precise control over the pore size. Since micropores provide numerous charge adsorption sites, and fewer mesopores and macropores help maintain a high packing density (0.53 g / mL), this invention significantly improves the specific surface area (2000 m² / mL). 2 While maintaining high volumetric energy storage performance, FeCl3 promotes the ordering of graphite microcrystalline structure and repairs some of the damaged layered structure during the first activation process, thereby better preserving the original graphite-like layered structure of needle coke, forming a continuous conductive network, improving electron transport capability and reducing device internal resistance. Compared with traditional single-stage activation methods, this invention effectively reduces the disordered generation of mesopores and macropores, avoids excessive etching of the graphite skeleton and pore structure collapse, and achieves a synergistic balance between high specific surface area, high filling density, excellent conductivity and structural stability.

[0020] 2. The graphite-like capacitor carbon prepared by this invention through a secondary synergistic activation process of KOH chemical activation and FeCl3 catalytic graphitization possesses a rich microporous structure, a high degree of graphitization, and a continuous conductive network. When assembled into a supercapacitor, it exhibits excellent energy storage performance and cycle stability. Due to the microporous structure providing numerous charge adsorption sites while maintaining a high packing density, the resulting capacitor carbon possesses both high specific capacitance (up to 154 F / g) and volumetric specific capacitance (up to 81.6 F / g). Simultaneously, the preservation of the graphite-like layered structure effectively enhances electron transport capability and reduces device internal resistance, thereby improving rate performance and cycle stability. After 10,000 cycles, the capacity decay is only 1.9%, demonstrating excellent electrochemical stability. Furthermore, because this invention uses low-ash needle coke as the carbon source and employs relatively small amounts of activator and catalyst, the residual inorganic impurities and metal ions are low after acid washing and water washing, further reducing device side reactions and leakage current, which is beneficial for improving the long-term cycle life of the supercapacitor.

[0021] 3. The secondary synergistic activation process provided by this invention has high operational safety, effectively reducing equipment corrosion and wear during traditional high alkali-to-carbon ratio enhanced activation processes, and decreasing equipment maintenance and depreciation costs. Simultaneously, this invention uses less chemical and catalytic activators, FeCl3 is widely available and low in cost, and generates less wastewater, waste gas, and residual inorganic salts during activation, making post-treatment impurity removal easier, which helps reduce environmental treatment costs and energy consumption in industrial production. Therefore, this invention not only has good process operability and industrial applicability but also effectively reduces production costs, showing promising prospects for industrial application. Detailed Implementation

[0022] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0023] Example 1. S1: Take 100 g of petroleum-based needle coke with a particle size of D50=25 μm and 140 g of KOH, with a mass ratio of petroleum-based needle coke to KOH of 1:1.4. Add KOH to a stainless steel beaker, add 90 mL of water, heat to 80℃, pour in needle coke powder, stir until it forms clumps, dry at 120℃ for 120 min, place in a tube furnace, heat to 740℃ at a rate of 5℃ / min under nitrogen atmosphere, hold for 150 min, and perform the first activation to obtain the activated product; allow it to cool naturally to 300℃, turn off the nitrogen, remove the activated product, add deionized water for dissolution, then transfer to a stainless steel container, add deionized water until the liquid level submerges the surface of the activated product; heat to 95℃ under stirring and hold for 30 min, then cool to room temperature and filter. The obtained filter cake was transferred back into a stainless steel container, and deionized water was added until the container was full. The mixture was heated to 95°C again under stirring and kept at that temperature for 30 min. After cooling, it was filtered. The above water washing process was repeated until the pH of the washing solution was ≤9. The filter cake was dried at 120°C for 120 min to obtain intermediate product A.

[0024] S2: Pour 12 g of ferric chloride into a beaker and add 30 mL of water. Stir to obtain a ferric chloride solution. Add 60 g of intermediate product A to the beaker. The mass ratio of intermediate product A to ferric chloride is 1:0.2. Stir until it forms a clump. Dry at 125℃ for 120 min. Place in a tube furnace and heat to 820℃ at a rate of 5℃ / min under a nitrogen atmosphere for a second activation. Hold at this temperature for 120 min to obtain the catalytic graphitization product. Allow to cool naturally to 200℃, turn off the nitrogen atmosphere, remove the catalytic graphitization product, add deionized water for dissolution, then transfer to a glass beaker. Add 2 mol of hydrochloric acid solution to submerge the surface of the catalytic graphitization product. Stir and heat to 70℃ for acid cooking for 60 min. Filter. Transfer the resulting filter cake back to the glass beaker, add deionized water to fill the container, and reheat to 100℃ under stirring and hold for 60 min. After 1 minute, filter again, repeating the process of adding water, stirring, heating, and filtering until the pH of the system stabilizes at 4 after washing, completing the first acid wash. Perform acid washing again using the same process as the first acid wash, adjusting the pH to 7 at the end of the water wash. Repeat the above acid washing-water washing three times, and dry the filter cake under vacuum at 110℃ for 180 minutes to obtain intermediate product B.

[0025] S3: Grind intermediate product B to a particle size of D50=7 μm, place it in a titanium steel can, and then put it into a high-temperature calcination furnace for refining and calcination under nitrogen protection. The calcination temperature is 760℃ and the calcination time is 90 min. After calcination, pour out the titanium steel can to obtain graphite-like capacitor carbon.

[0026] Example 2. The difference between this embodiment and Example 1 is that the needle coke is coal-based needle coke calcined coke, the mass ratio of the coal-based needle coke calcined coke to KOH is 1:1.5; the mass ratio of intermediate product A to ferric chloride is 1:0.17; the temperature of the first activation is 750℃; the remaining preparation steps and conditions are the same as in Example 1, and graphite-like capacitor carbon is obtained.

[0027] Example 3. The difference between this embodiment and Example 1 is that the mass ratio of petroleum-based needle coke to KOH is adjusted to 1:1.6. The remaining preparation steps and conditions are the same as in Example 1, resulting in graphite-like capacitor carbon.

[0028] Example 4. The difference between this embodiment and Example 1 is that the mass ratio of intermediate product A to ferric chloride is adjusted to 1:0.5, while the remaining preparation steps and conditions are the same as in Example 1, resulting in graphite-like capacitor carbon.

[0029] Example 5. The difference between this embodiment and Example 1 is that the particle size of the petroleum-based needle coke is adjusted to D50=50 μm, while the rest of the preparation steps and conditions are the same as in Example 1, resulting in graphite-like capacitor carbon.

[0030] Example 6. The difference between this embodiment and Example 1 is that the temperature of the first activation is adjusted to 780℃ and the holding time is 120min. The remaining preparation steps and conditions are the same as in Example 1, resulting in graphite-like capacitor carbon.

[0031] Example 7. The difference between this embodiment and Example 1 is that the temperature of the second activation is adjusted to 850℃ and the holding time is 100min. The remaining preparation steps and conditions are the same as in Example 1, resulting in graphite-like capacitor carbon.

[0032] Comparative Example 1. S1: Pour 300 g of solid potassium hydroxide into a beaker containing 5% ethanol solution, stir to dissolve, then add 100 g of petroleum-based needle coke with a particle size of 300 mesh, stir evenly, and place in a drying oven to dry at 120℃ for 240 min. Activate the dried petroleum-based needle coke in a nickel boat, then place it in a tube furnace, purge with nitrogen, and heat to 400℃ at a rate of 3℃ / min, holding for 3 h. Then heat to 850℃ at a rate of 5℃ / min, holding for 210 min, and allow to cool naturally to 200℃. Turn off the nitrogen, remove the activated material, and dissolve it in deionized water. Transfer to a stainless steel container, add deionized water until the surface of the activated product is submerged, heat to a gentle boil under stirring, and hold for 30 min. After completion, cool to room temperature and filter. The resulting filter cake was transferred back into a stainless steel container, and deionized water was added until the container was full. The mixture was then heated to 100°C and kept at that temperature for 30 minutes under stirring. After cooling, the mixture was filtered. The above washing process was repeated until the pH of the washing solution was 9.

[0033] The filter cake was then transferred to a glass beaker, and 2 mol of hydrochloric acid solution was added to submerge the carbon surface. The mixture was stirred and heated to 70°C for 1 hour of acid cooking. After filtration, the resulting filter cake was transferred back to the glass beaker, and deionized water was added until the container was full. The mixture was then heated again to 100°C under stirring and held for 1 hour. The process of adding water, stirring, heating, and filtering was repeated until the pH of the system stabilized at 4 after washing, completing the first acid wash. Acid washing was then performed again using the same process as the first acid wash, with the pH adjusted to 7 at the end of the water wash. This acid wash-water wash cycle was repeated three times. The filter cake was then dried under vacuum at 120°C for 180 minutes to obtain intermediate product B.

[0034] S3: Grind intermediate product B to a particle size of D50=7 μm, place the intermediate product B powder in a titanium steel can, and then put it into a high-temperature calcination furnace for refining and calcination under nitrogen protection. The calcination temperature is 760℃ and the calcination time is 90 min. After calcination, pour out the titanium steel can to obtain capacitor carbon.

[0035] The physicochemical properties of the capacitor carbon prepared in Examples 1-7 and Comparative Example 1 were tested, and the results are shown in Table 1 below. As can be seen from the table, the specific surface area of ​​the capacitor carbon prepared in Example 1 reached 2000 m². 2The carbon had a packing density of 0.53 g / mL, an ash content of 0.03%, a total metal ion content of 0.018%, a graphitization density (ID / IG) of 0.45, a total pore volume of 0.92 cm³ / g, and a micropore volume ratio of 90.1%, indicating that it possesses a rich microporous structure, high packing density, and a good graphitization-like structure. Examples 2-7 showed no significant fluctuations compared to Example 1, maintaining a high specific surface area, a high micropore volume ratio, low ash content and metal ion residue, and exhibiting a high degree of graphitization and good electron transport performance. In Examples 2 and 3, the mass ratio of needle-shaped coke to KOH was increased to 1:1.5 and 1:1.6, respectively, resulting in capacitive carbon with specific surface areas of 1976 m². 2 / g and 2084 m 2 The micropore volume ratios were 89.7% and 90.2% respectively, indicating that appropriately increasing the KOH dosage is beneficial to enhancing the chemical activation pore-forming effect and forming a well-developed microporous structure. However, when the KOH dosage was further increased, the filling density of Example 3 slightly decreased to 0.50 g / mL, indicating that excessive alkaline etching may reduce the density of the carbon material skeleton to some extent. In Example 4, the mass ratio of intermediate product A to ferric chloride was increased to 1:0.5. Compared with Example 1, its specific surface area slightly decreased to 1958 m². 2 / g, the packing density was maintained at 0.53 g / mL, and the ID / IG value decreased to 0.40, indicating that increasing the amount of ferric chloride is beneficial to promoting catalytic graphitization and improving the structural order of carbon materials; however, the ash content and total metal ion content increased slightly, indicating that excessive ferric chloride may increase the risk of inorganic residues.

[0036] Example 5 adjusted the particle size of petroleum-based needle coke to a D50 of 50 μm. Compared to Example 1, its specific surface area decreased to 1903 m². 2 The packing density was increased to 0.54 g / mL, and the micropore volume ratio was increased to 91.0%, indicating that appropriately increasing the raw material particle size is beneficial for maintaining a high packing density and micropore ratio, but may affect the diffusion of the activator into the particle interior, resulting in a slight decrease in specific surface area. In Example 6, the first activation temperature was increased to 780℃ and held for 120 min. Compared to Example 1, its specific surface area increased to 2065 m². 2 The micropore volume ratio increased to 90.3%, indicating that increasing the first KOH activation temperature is beneficial for enhancing the pore-forming effect; however, the filling density decreased to 0.50 g / mL, indicating that excessive activation may lead to intensified etching of the carbon skeleton, affecting the material's density. In Example 7, the second activation temperature was increased to 850℃ and held for 100 min. Compared to Example 1, its specific surface area remained basically stable at 1997 m². 2 / g, the packing density was maintained at 0.53 g / mL, the ash content was reduced to 0.024%, and the ID / IG value was 0.46. This indicates that appropriately increasing the second catalytic activation temperature is beneficial for further regulating the structure and reducing the ash content, while still maintaining a good pore structure and packing density.

[0037] In summary, under different raw material ratios, ferric chloride dosages, raw material particle sizes, and activation temperatures, Examples 2-7 showed no significant performance changes compared to Example 1. This indicates that the present invention, through the use of KOH for the first chemical activation to create pores, combined with FeCl3 for the second catalytic activation, effectively promotes the ordered structure of graphite microcrystals and the maintenance of the conductive network while constructing a rich microporous structure, achieving a synergistic balance between high specific surface area, high filling density, and low ash content. In contrast, Comparative Example 1, which only used KOH for the first chemical activation, resulted in a significantly lower specific surface area and filling density of the prepared capacitor carbon compared to the examples, with a specific surface area of ​​only 1250 m². 2 The material has a filling density of 0.43 g / mL, and the ash content and total metal ion content increase to 0.16% and 0.056%, respectively. Moreover, the graphitization degree (ID / IG) is as high as 0.78, indicating that the material has many defects and high structural disorder, which is not conducive to the maintenance of the electron transport network. This shows that single KOH activation can easily lead to the destruction of the graphite skeleton and the disorder of the pore structure. However, the present invention can effectively balance the construction of pore structure, maintenance of graphite-like structure and material structural stability through secondary synergistic activation.

[0038] Table 1

[0039] The electrochemical performance of the capacitor carbon prepared in Examples 1-7 and Comparative Example 1 was tested, and they were assembled into coin-type supercapacitors. The performance was evaluated using the organic electrolyte tetraethylammonium tetrafluoroborate / acetonitrile (Et4NBF4 / AN). The test results are shown in Table 2. As can be seen from the table, Example 1, after 150 cycles at a charging voltage of 2.7 V and a charging current of 0.05 A, achieved a specific capacitance of 154 F / g and a volumetric capacitance of 81.6 F / g. After 10,000 cycles, the specific capacitance decreased by only 2.5%, demonstrating excellent electrochemical stability. Examples 2-7, under the same test conditions, showed no significant fluctuations in specific capacitance, volumetric capacitance, and the specific capacitance after 10,000 cycles, also exhibiting high cycle stability. This indicates that the present invention constructs a microporous structure through the first chemical activation with KOH, combined with a second catalytic graphitization treatment with FeCl3. This effectively maintains the graphite-like conductive network and structural stability while improving the specific surface area and charge storage capacity, thus achieving a balance between high specific capacitance, high volumetric capacitance, and long cycle life. In contrast, Comparative Example 1, under the same conditions, had a mass specific capacitance of only 83 F / g and a volumetric specific capacitance of only 35 F / g. After 10,000 cycles, the mass specific capacitance decreased by as much as 43%, indicating that traditional single-cycle activation methods easily cause disordered pore structures and damage to the graphite framework, which is detrimental to electron and ion transport, leading to a significant decrease in the material's energy storage performance and cycle stability. These results further verify that the secondary synergistic activation process of KOH activation and FeCl3 catalytic graphitization in this invention can effectively achieve a synergistic unity between pore structure construction, graphite-like structure maintenance, and improved electrochemical stability.

[0040] Table 2

[0041] In summary, this invention employs a two-stage synergistic activation of needle coke using both chemical and catalytic activators. The first low-temperature chemical activation constructs a 0.7 nm ultraporous structure within the needle coke, and the second catalytic graphitization process further broadens and restructures these ultraporous pores, resulting in a pore structure system dominated by 0.7–2 nm micropores, thus achieving precise control over the pore size. Since micropores provide numerous charge adsorption sites, and fewer mesopores and macropores help maintain a high packing density (0.53 g / mL), this invention significantly improves the specific surface area (2000 m² / mL). 2While maintaining high volumetric energy storage performance, FeCl3 promotes the ordering of graphite microcrystalline structure and repairs some of the damaged layered structure during the first activation process, thus better preserving the original graphite-like layered structure of needle coke and forming a continuous conductive network. The assembled supercapacitor exhibits excellent energy storage performance and cycle stability. Furthermore, the secondary synergistic activation process provided by this invention has high operational safety, requires less chemical and catalytic activators, and utilizes widely available and low-cost FeCl3. The activation process generates less wastewater, waste gas, and residual inorganic salts, and post-treatment impurity removal is easier, which helps reduce environmental treatment costs and industrial production energy consumption. Therefore, this invention not only has good process operability and industrial applicability but also effectively reduces production costs and has good prospects for industrial application.

[0042] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0043] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. 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 the invention. Therefore, the invention 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 disclosed herein.

Claims

1. A method for preparing graphite-like capacitor carbon, characterized in that, The preparation steps include the following: S1: Mix needle-shaped coke powder with an aqueous solution of chemical activator, stir, dry, and place in an activation furnace for the first activation to obtain an activated product. The activated product is then post-treated to obtain intermediate product A. S2: Mix intermediate product A with an aqueous solution of catalytic activator, dry, and place in an activation furnace for a second activation to obtain catalytic graphitization product. After post-treatment of the catalytic product, intermediate product B is obtained. S3: Grind and calcine intermediate product B to obtain graphite-like capacitor carbon.

2. The method for preparing graphite-like capacitor carbon according to claim 1, characterized in that, The needle-shaped coke powder in S1 has a particle size of 25-50 μm; the chemical activator is any one or a combination of two of potassium hydroxide and sodium hydroxide; the mass ratio of the needle-shaped coke powder to the chemical activator is 1:1.3-1.6; the stirring is carried out until the mixture forms a clump; the drying temperature is 100-140℃ and the time is 100-140 min.

3. The method for preparing graphite-like capacitor carbon according to claim 1, characterized in that, The first activation described in S1 is carried out in an inert gas atmosphere; the temperature of the first activation is 740~780℃; and the holding time of the first activation is 120~180 min. The post-processing steps of the activated product include: washing and drying the activated product; the drying time is 120~140 min; and the drying temperature is 100~140℃.

4. The method for preparing graphite-like capacitor carbon according to claim 1, characterized in that, The catalytic activator in S2 is any one or a combination of at least two of ferric chloride, zinc chloride, and nickel chloride; the mass ratio of intermediate product A to catalytic activator is 1:0.1 to 1:0.5; the drying temperature is 120 to 130°C and the drying time is 110 to 130 min.

5. The method for preparing graphite-like capacitor carbon according to claim 1, characterized in that, The second activation in S2 is carried out in an inert gas atmosphere; the temperature of the second activation is 800~850℃; the holding time of the second activation is 100~140 min; the post-processing steps of the catalytic graphitization product include: washing and drying the catalytic graphitization product; the washing includes acid washing and water washing; the drying time is 170~190 min and the temperature is 100~120℃.

6. The method for preparing graphite-like capacitor carbon according to claim 1, characterized in that, The intermediate product B mentioned in S3 has a particle size of D50 = 6~9 μm; the calcination temperature is 730~760℃, the calcination time is 90~110 min; and the calcination atmosphere is nitrogen.

7. The method for preparing graphite-like capacitor carbon according to claim 1, characterized in that, The pore size of the graphite-like capacitor carbon is 0.7~2 nm; the particle size of the graphite-like capacitor carbon is D50=6~8 μm.

8. The method for preparing graphite-like capacitor carbon according to claim 3 or 5, characterized in that, The inert gas is either nitrogen or argon.

9. A graphite-like capacitor carbon, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. An application of the graphite-like capacitor carbon as described in claim 9, characterized in that, It is used in the field of supercapacitors.

Images