A method for preparing high-performance energy storage carbon material based on acid treatment and wet carbon pyrolysis

Abstract

This invention discloses a method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis. The method involves preliminary mechanical acid infiltration of a high-carbon content material with an inorganic oxyacid solution in a highly dispersed stirring and mixing device to obtain a pre-infiltrated material. This pre-infiltrated material is then dispersed into random particles by a toothed mixer, followed by medium-temperature carbonization, activation, acid recovery, washing, and dehydration to obtain a wet carbon precursor. The wet carbon precursor is then subjected to high-temperature heat treatment in a relatively closed high-temperature environment, rapidly heated to utilize the atmosphere released by the precursor itself, to obtain a heat-treated material. After alkali and acid washing, the heat-treated material is further subjected to high-temperature treatment under an inert atmosphere, followed by pulverization, grading, and iron removal to obtain the energy storage carbon material. The inorganic oxyacid synergistic multi-stage mechanical pretreatment ensures uniform activator distribution. The rapid heating of the wet carbon generates a self-activated pore structure, avoiding external activator residue contamination. The resulting energy storage carbon material exhibits a uniform and highly reproducible pore structure, significantly improving the energy density and power density of energy storage devices.

Description

Technical Field

[0001] This invention relates to the field of carbon materials technology, and in particular to a method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis. Background Technology

[0002] With the global energy structure transformation and the rapid development of renewable energy, high-efficiency energy storage technology has become crucial for promoting clean energy utilization, smart grid construction, and the advancement of the electric vehicle industry. Among numerous energy storage devices, supercapacitors, lithium-ion batteries, and sodium-ion batteries have attracted widespread attention due to their high power density, long cycle life, and rapid charge-discharge characteristics. Electrode materials, as a core component of energy storage devices, directly determine the energy density, power density, and cycle stability of the energy storage system.

[0003] Porous carbon materials have become one of the most promising electrode materials due to their advantages such as high specific surface area, tunable pore system, good conductivity, chemical stability, and relatively low cost. Ideal energy storage carbon materials should possess the following characteristics: high specific surface area to provide abundant active sites; a reasonable pore size distribution, where micropores (<2nm) help improve charge storage capacity, mesopores (2-50nm) facilitate rapid ion transport, and macropores (>50nm) can serve as ion buffer spaces; a good conductive network to ensure efficient electron transport; and high carbon purity and structural stability to guarantee long-term cycling performance.

[0004] Currently, the main methods for preparing porous carbon materials include physical activation and chemical activation. Physical activation typically uses water vapor or carbon dioxide as activators to etch and create pores in the carbon precursor at high temperatures. Chemical activation usually involves mixing the raw material with an activator (such as KOH, NaOH, ZnCl2, or H3PO4) before carbonization, and forming the porous structure through the etching and catalytic effects of the activator at high temperatures. Common pitfalls in these methods include insufficient pretreatment of the raw materials, which can lead to uneven distribution of the activator and poor uniformity of the pore structure and reproducibility of the electrochemical performance in the final product.

[0005] In recent years, the preparation of high-performance energy storage carbon materials using biomass, synthetic polymers, and other carbon sources through controllable processes has become a research hotspot. However, in existing technologies, it is difficult to achieve precise control of the pore structure of energy storage carbon materials and to balance high microporosity and high medium porosity; the balance between material density, conductivity, and porosity is also difficult to achieve. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis, so as to achieve precise construction of the pore system of carbon materials and obtain carbon materials with high microporosity, suitable mesopore ratio and high purity, so as to meet the strict requirements of high-performance energy storage devices for electrode materials.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by this invention is as follows: A method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis, comprising: High-carbon content materials and inorganic oxygen-containing acid solutions are transported to a high-dispersion stirring and mixing equipment according to a preset ratio, and after preliminary mechanical acid infiltration, a preliminary infiltrated material is obtained; The initial permeate is conveyed to a multi-stage roller mill, which includes two or more roller mills arranged sequentially along the conveying direction. The roller mill gaps are gradually reduced, and the material undergoes full permeation treatment under mechanical force to obtain permeate. The permeate is fed into a toothed mixer and dispersed to obtain random particles; Random particles were sequentially subjected to medium-temperature carbonization, activation, acid recovery, washing, and dehydration to obtain a wet carbon precursor. The wet carbon precursor is placed in a high-temperature, relatively closed environment and rapidly heated to 550℃~850℃ within 0.5h. The high-temperature heat treatment is carried out using the atmosphere released by the wet carbon precursor itself to obtain the heat-treated material. The heat-treated material is subjected to alkali washing, alkali washing, acid washing, acid washing, and drying in sequence to obtain a dried intermediate. The dried intermediate was subjected to high-temperature treatment under an inert atmosphere, and then crushed, graded, and iron removed to obtain the energy storage carbon material.

[0008] In some embodiments, the high-carbon content material is selected from at least one of biomass materials, synthetic resins, starch, and petroleum coke; The biomass material is at least one of peach shell powder, apricot shell powder, palm kernel shell powder, peach kernel shell powder, coconut shell powder, wood chips, and bamboo chips; the synthetic resin is at least one of phenolic resin, polystyrene crosslinking resin, furfural resin, furan resin, and epoxy resin; and the petroleum coke is at least one of raw coke or pre-calcining coke.

[0009] In some embodiments, the inorganic oxyacid is at least one of sulfuric acid, nitric acid, or phosphoric acid; The mass concentration of sulfuric acid is 1%~80%, the mass concentration of nitric acid is 1%~70%, and the mass concentration of phosphoric acid is 40%~85%. In the mass ratio of inorganic oxyacids to high-carbon content materials, the mass ratio of pure sulfuric acid to high-carbon content materials is 0~1:1, the mass ratio of pure nitric acid to high-carbon content materials is 0~1:1, and the mass ratio of pure phosphoric acid to high-carbon content materials is 0.8~2.5:1.

[0010] In some embodiments, the initial mechanical acid permeation temperature is 60°C to 150°C, and the time is 1 hour to 6 hours; The compaction gap of a multi-stage roller compactor decreases progressively. When three roller compactors are used, the compaction gap of the first stage is 10mm, the compaction gap of the second stage is 6mm, and the compaction gap of the third stage is 2mm.

[0011] In some embodiments, the temperature for medium-temperature carbonization is 160℃~300℃, and the carbonization time is 1h~12h; The activation temperature is 400℃~600℃, and the holding time is 10min~60min; Acid recovery is achieved by using six or more water washing tanks filled with activating material in series for gradient acid recovery and gradient washing. After washing, the carbon slurry is filtered to remove surface water while retaining adsorbed water inside the carbon.

[0012] In some embodiments, the high-temperature relatively sealed environment is a slightly positive pressure environment, with a specific exhaust port. During the reaction process, excess gas is discharged from the exhaust port, and the slightly positive pressure of the high-temperature relatively sealed environment is maintained. The heat treatment holding time is 10 min to 60 min.

[0013] In some embodiments, the alkaline washing uses a sodium hydroxide solution with a mass concentration of 1% to 5%, the mass of the added sodium hydroxide solution is 3 to 6 times that of the heat-treated material, the alkaline washing temperature is 70°C to 100°C, and the alkaline washing time is 0.5h to 4h. The washing endpoint of alkali washing is when the pH of the filtered water is 8-10.

[0014] In some embodiments, pickling uses a hydrochloric acid solution with a mass concentration of 1% to 10%, the mass of the hydrochloric acid solution added is 3 to 6 times that of the heat-treated material, the pickling temperature is 70°C to 95°C, and the pickling time is 0.5h to 4h. The washing endpoint for acid washing is when the pH of the filtered water is greater than 6.

[0015] In some embodiments, the inert atmosphere is at least one of nitrogen and helium, the fine treatment temperature is 600°C to 1200°C, and the fine treatment time is 0.5h to 3h.

[0016] In some embodiments, the pore size distribution of the energy storage carbon material is calculated using a DFT model based on the nitrogen adsorption isotherm. The pore volume percentage of the microporosity (0-3 nm) is ≥70%, the pore volume percentage of the macroporosity (greater than 10 nm) is ≤10%, and the pore volume is ≥0.6 cm³. 3 / g, with a specific surface area of ​​1000m² / g to 2500m² / g and an average pore size of 1nm to 10nm.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: Unlike existing technologies, the above technical solution involves initial mechanical acid permeation of high-carbon content materials with inorganic oxygen-containing acid solutions in a highly dispersed mixing device to obtain a pre-permeable material. This material is then fully permeated by mechanical force through a multi-stage mill with progressively smaller milling gaps to obtain a permeable material. After being dispersed into random particles by a toothed mixer, the material undergoes medium-temperature carbonization, activation, acid recovery, washing, and dehydration to obtain a wet carbon precursor. The wet carbon precursor is then placed in a high-temperature, relatively enclosed environment for rapid heating and high-temperature heat treatment using the atmosphere it releases to obtain a heat-treated material. This material is then subjected to alkali washing, alkali washing, acid washing, acid washing, and drying to obtain a dried intermediate. Finally, after high-temperature treatment under an inert atmosphere, the material is pulverized, graded, and iron removed to obtain an energy storage carbon material. By using inorganic oxyacids in conjunction with multi-stage mechanical pretreatment to ensure uniform distribution of the activator, and utilizing the self-activation and pore-forming of wet carbon at high temperatures, the residual contamination of external activators is avoided. The resulting energy storage carbon material has a uniform and highly reproducible pore structure, and possesses excellent characteristics of high microporosity, high pore volume, and high specific surface area. It meets the requirements of high-capacity storage and rapid ion transport, and can significantly improve the energy density and power density of energy storage devices. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This embodiment provides a method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis, including: High-carbon content materials and inorganic oxygen-containing acid solutions are transported to a high-dispersion stirring and mixing equipment according to a preset ratio, and after preliminary mechanical acid infiltration, a preliminary infiltrated material is obtained; The initial permeate is conveyed to a multi-stage roller mill, which includes two or more roller mills arranged sequentially along the conveying direction. The roller mill gaps are gradually reduced, and the material undergoes full permeation treatment under mechanical force to obtain permeate. The permeate is fed into a toothed mixer and dispersed to obtain random particles; Random particles were sequentially subjected to medium-temperature carbonization, activation, acid recovery, washing, and dehydration to obtain a wet carbon precursor. The wet carbon precursor is placed in a high-temperature, relatively closed environment and rapidly heated to 550℃~850℃ within 0.5h. The high-temperature heat treatment is carried out using the atmosphere released by the wet carbon precursor itself to obtain the heat-treated material. The heat-treated material is subjected to alkali washing, alkali washing, acid washing, acid washing, and drying in sequence to obtain a dried intermediate. The dried intermediate was subjected to high-temperature treatment under an inert atmosphere, and then crushed, graded, and iron removed to obtain the energy storage carbon material.

[0020] High-carbon-content materials refer to solid raw materials with a high carbon content that can serve as carbon precursors, including biomass materials, synthetic resins, starch, or petroleum coke, providing the carbon framework for the final energy storage carbon materials. Inorganic oxyacid solutions are aqueous solutions containing at least one of sulfuric acid, nitric acid, or phosphoric acid, acting as pore-forming agents and structural modifiers. During subsequent heat treatment, these solutions chemically etch the carbon framework to form pores. The preset ratio refers to the feeding ratio determined based on the selected inorganic oxyacid type and target pore structure, according to the mass ratio of pure acid to high-carbon-content material. For example, when using phosphoric acid, the preferred mass ratio of pure phosphoric acid to material is 0.8~2.5:1. This ratio directly affects the degree of subsequent pore formation.

[0021] High-dispersion mixing equipment refers to a stirring device capable of achieving high-shear and high-turbulence mixing, enabling inorganic oxygen-containing acid solutions to fully contact and initially penetrate high-carbon-content materials in the liquid phase, laying the foundation for subsequent deep mechanical penetration. Preliminary mechanical acid penetration refers to the process where, within a certain temperature (preferably 60℃-150℃) and a certain time (preferably 1h~6h), the mechanical force applied through stirring promotes the initial diffusion of acid into the material's interior, achieving homogeneous mixing of acid and material to obtain initially penetrated material. The shearing action of high-dispersion stirring breaks up material surface agglomerates, allowing the acid to initially wet the material's outer surface and shallow pores, creating conditions for subsequent multi-stage compaction and deeper penetration.

[0022] The initial permeate is conveyed to a multi-stage compactor, which consists of two or more compactors arranged sequentially along the conveying direction. A compactor is a rolling device composed of relatively rotating rolling cylinders, where the material is squeezed and sheared within the compaction gaps. The progressively decreasing compaction gaps mean that the spacing between each stage of the compactor decreases sequentially along the conveying direction. For example, when using three compactors, a preferred design is a 10mm gap for the first stage, a 6mm gap for the second stage, and a 2mm gap for the third stage. This progressively decreasing design subjects the material to gradually increasing extrusion and shear forces at each stage. Under this mechanical force, the acid is forced into the micropores and interlayer structure of the material, achieving thorough permeation and yielding the permeated material. Multi-stage compaction, through progressively increasing mechanical stress, continuously squeezes the acid from the surface of the initial permeate into the material's interior. Simultaneously, shearing forces cause plastic deformation and interlayer delamination in the material structure, significantly improving the uniformity of acid distribution and penetration depth within the material, ensuring the uniformity of the pore-forming reaction during subsequent thermal activation.

[0023] A toothed agitator is a dispersion device equipped with high-speed rotating agitators. It breaks down permeable materials that may stick together or clump after multi-stage crushing into irregular, fine particles, i.e., random particles. After multi-stage crushing, the material may be in the form of flakes or lumps due to compression. If it is not dispersed, the heat and mass transfer inside the particles will be uneven during the subsequent carbonization and activation process, affecting the uniformity of the pore structure. Through the high-speed agitation of the toothed agitator, the material is broken into random particles with a wider particle size distribution, increasing the specific surface area. This is beneficial for gas escape and heat transfer during subsequent heat treatment, while also maintaining the distribution of acid solution inside the particles.

[0024] Medium-temperature carbonization refers to heat treatment of random particles at a relatively low temperature (preferably 160℃~300℃), causing preliminary pyrolysis of the organic components in the material to form a preliminary carbon skeleton structure. Simultaneously, some inorganic oxyacids are decomposed or converted into active species, preparing active sites for subsequent activation reactions. Activation involves heat treatment of the carbonized products at a higher temperature (preferably 400℃~600℃). At this temperature, inorganic oxyacids or their decomposition products chemically react with the carbon skeleton, etching carbon atoms to form a porous structure. Simultaneously, some acids are reduced or decomposed into gases and escape. Acid recovery involves gradient acid recovery and washing using six or more water washing tanks filled with activated material in series. Free acids remaining in the carbon material after activation are recovered and reused through countercurrent washing, reducing production costs. Washing further removes residual acid and impurities from the carbon material surface with clean water. Dehydration removes adsorbed free water from the carbon material surface using a filter, but retains adsorbed water in the internal pores of the carbon material, thus obtaining a wet carbon precursor.

[0025] The organic precursor is converted into a carbon skeleton with a certain mechanical strength through medium-temperature carbonization. Then, the inorganic oxyacid reacts with the carbon skeleton through high-temperature activation to form a preliminary porous structure. Subsequently, free acid is removed by acid recovery and washing, while the internal adsorbed water is deliberately retained to provide the atmosphere required for self-activation in the subsequent wet carbon heat treatment steps.

[0026] A high-temperature, relatively closed environment refers to a sealed reaction vessel that maintains a slight positive pressure and has specific exhaust ports. This prevents the self-atmosphere released by the wet carbon precursor during rapid heating from dissipating quickly, thus forming a high-concentration active atmosphere around the material. Rapidly heating to 550℃~850℃ within 0.5 hours means raising the wet carbon precursor from room temperature to the target temperature in a very short time (no more than 0.5 hours). This causes the volatiles and moisture inside the wet carbon precursor to rapidly vaporize, generating an active atmosphere. Simultaneously, the carbon skeleton reacts with this atmosphere at high temperature, thereby etching, expanding, and rebuilding existing pores, achieving pore reconstruction and densification optimization. High-temperature heat treatment using the atmosphere released by the wet carbon precursor itself means that the entire heat treatment process does not introduce any additional activating gases; it relies entirely on the atmosphere generated by the vaporization of the wet carbon precursor at high temperature for the activation reaction, resulting in a heat-treated material.

[0027] During the rapid heating process, the wet carbon precursor forms a local high-pressure environment in the micropores of the material, causing the carbon skeleton to undergo a gasification reaction. On the one hand, it expands and connects the existing pores, and on the other hand, it consumes some carbon atoms through the reaction to achieve densification. At the same time, the gas produced by the reaction is discharged from the exhaust port to maintain a slightly positive pressure environment to prevent external air from entering.

[0028] The heat-treated material is subjected to a series of processes including alkali washing, alkali washing, acid washing, acid washing, and drying to obtain a dried intermediate. Alkali washing involves immersing the heat-treated material in a sodium hydroxide solution (preferably 1%–5% by mass) under heating conditions (preferably 70℃–100℃) to dissolve and remove non-carbon impurities (such as silica ash) and residual acidic substances that may be generated during heat treatment. Alkali washing involves washing with clean water until the pH of the filtered water reaches (preferably 8–10) to remove free alkali adsorbed on the surface of the carbon material. Acid washing involves immersing the alkali-washed material in a hydrochloric acid solution (preferably 1%–10% by mass) under heating conditions (preferably 70℃–95℃) to neutralize residual alkali and dissolve impurities such as metal oxides. Acid washing involves washing with clean water until the pH of the filtered water is greater than 6 to remove residual acid and dissolved metal ions. Drying removes surface moisture from the material to obtain the dried intermediate. By alternating alkaline and acid washing, the ash, metal oxides and other non-carbon impurities generated during heat treatment are removed through acid-base neutralization and dissolution, thereby improving the purity of carbon materials and providing high-purity carbon precursors for subsequent refining.

[0029] An inert atmosphere refers to an atmosphere composed of protective gases such as nitrogen and helium that do not participate in the reaction of carbon materials, preventing the carbon materials from being oxidized at high temperatures. High-temperature treatment refers to heat-treating the dried intermediate at a temperature preferably between 600℃ and 1200℃ to further repair structural defects in the carbon skeleton, improve the graphitization degree and conductivity of the carbon material, and stabilize the formed porous structure. Subsequently, the material undergoes crushing, grading, and iron removal. Crushing involves breaking the high-temperature treated blocky or agglomerated carbon material into fine particles; grading involves obtaining particles within the target particle size range through methods such as sieving or air classification; and iron removal involves removing any ferromagnetic impurities that may have been introduced into the carbon material using methods such as magnetic separation, ultimately yielding the energy storage carbon material.

[0030] This embodiment uses high-carbon-content materials as the carbon source. A multi-stage permeation of inorganic oxyacids under mechanical force achieves uniform acid distribution within the material. The acid is then dispersed by a stirring tooth to form random particles, ensuring uniform pore-forming reactions during subsequent carbon activation. The medium-temperature carbonization and activation steps utilize the chemical reaction between the inorganic oxyacids and the carbon skeleton to construct a preliminary porous structure. Acid recovery and dehydration yield a wet carbon precursor with internally retained adsorbed water. During rapid heating, the wet carbon precursor undergoes self-activation heat treatment using the atmosphere it releases, achieving pore reconstruction and densification optimization, avoiding impurity contamination from externally introduced activators. Subsequent alternating alkali and acid washing effectively removes ash and metallic impurities, improving the purity of the carbon material. The final high-temperature refining process further repairs carbon structural defects and enhances conductivity.

[0031] This embodiment significantly improves the uniformity of pore-forming agent distribution in the carbon precursor through inorganic oxyacid synergistic multi-stage mechanical pretreatment, resulting in a substantial improvement in the uniformity of pore structure and the reproducibility of electrochemical performance of the obtained energy storage carbon material. The wet carbon self-activation heat treatment process fully utilizes the atmosphere released by the wet carbon precursor at high temperature for pore-forming and densification treatment, simplifying the process flow, reducing production costs, and avoiding impurity contamination introduced by external activators. The resulting energy storage carbon material possesses excellent pore structure characteristics of high microporosity, high pore volume, and high specific surface area, meeting the requirements of high-capacity storage and rapid ion transport, and can significantly improve the energy density and power density of energy storage devices, showing broad application prospects.

[0032] In some embodiments, the high-carbon content material is selected from at least one of biomass materials, synthetic resins, starch, and petroleum coke; The biomass material is at least one of peach shell powder, apricot shell powder, palm kernel shell powder, peach kernel shell powder, coconut shell powder, wood chips, and bamboo chips; the synthetic resin is at least one of phenolic resin, polystyrene crosslinking resin, furfural resin, furan resin, and epoxy resin; and the petroleum coke is at least one of raw coke or pre-calcining coke.

[0033] In this embodiment, biomass material refers to natural polymer materials derived from plants, which have high carbon content and are widely available. Specifically, at least one of peach shell powder, apricot shell powder, palm kernel shell powder, peach kernel shell powder, coconut shell powder, sawdust, or bamboo shavings can be selected. These materials have rich natural pore structures and high carbon yield, which is beneficial for the subsequent pore-forming reaction to form a well-developed pore system.

[0034] Synthetic resins refer to artificially synthesized high-molecular polymers with uniform composition and low impurity content. Specifically, at least one of phenolic resins, cross-linked polystyrene resins, furfural resins, furan resins, or epoxy resins can be selected. These materials exhibit a regular structure after carbonization, which is beneficial for obtaining energy storage carbon materials with concentrated pore size distribution. Starch, as a natural polysaccharide polymer, forms a unique microstructure in its carbon skeleton after carbonization. Petroleum coke, a byproduct of petroleum refining, has an extremely high carbon content. At least one of raw coke or pre-calcining coke can be selected; its carbon layer structure is relatively ordered, and after activation treatment, it easily forms carbon materials with a high specific surface area.

[0035] The basis for selecting the above-mentioned materials as high-carbon materials in this embodiment is that they all have high carbon content and controllable microstructure, can fully react with inorganic oxyacids and form the target pore structure in subsequent heat treatment, and are abundant in source, controllable in cost, and suitable for large-scale industrial production.

[0036] In some embodiments, the inorganic oxyacid is at least one of sulfuric acid, nitric acid, or phosphoric acid; The mass concentration of sulfuric acid is 1%~80%, the mass concentration of nitric acid is 1%~70%, and the mass concentration of phosphoric acid is 40%~85%. In the mass ratio of inorganic oxyacids to high-carbon content materials, the mass ratio of pure sulfuric acid to high-carbon content materials is 0~1:1, the mass ratio of pure nitric acid to high-carbon content materials is 0~1:1, and the mass ratio of pure phosphoric acid to high-carbon content materials is 0.8~2.5:1.

[0037] In this embodiment, sulfuric acid is a strong acid, which is mainly used as a dehydrating agent and oxidizing agent in the preparation of carbon materials. It can promote the cross-linking and preliminary carbonization of carbon precursors. Its mass concentration can be selected in the range of 1% to 80%. The higher the concentration, the stronger the dehydration ability, but excessively high concentration may lead to over-oxidation.

[0038] Nitric acid has both acidic and oxidizing properties, enabling it to oxidize and etch carbon precursors at relatively low temperatures, introducing oxygen-containing functional groups and promoting pore formation. Its mass concentration can be selected from 1% to 70%.

[0039] Phosphoric acid is a commonly used chemical activator. During heat treatment, it can react with the carbon skeleton to form phosphates, leaving pores after washing. Its mass concentration can be selected in the range of 40% to 85%. If the concentration is too low, the activation effect will be insufficient, and if the concentration is too high, it may cause over-etching.

[0040] Regarding the mass ratio of inorganic oxyacids to high-carbon content materials, the mass ratio of pure sulfuric acid to high-carbon content materials can be selected from 0 to 1:1, the mass ratio of pure nitric acid to high-carbon content materials can be selected from 0 to 1:1, and the mass ratio of pure phosphoric acid to high-carbon content materials can be selected from 0.8 to 2.5:1. The selection of this mass ratio directly affects the degree of pore formation. If the ratio is too low, the activation will be insufficient, and if the ratio is too high, it may lead to excessive etching of the carbon skeleton and collapse.

[0041] This embodiment utilizes the chemical properties of different acids to achieve differentiated pore-forming effects. Sulfuric acid and nitric acid focus on surface modification and mild pore-forming, while phosphoric acid focuses on deep pore-forming. By adjusting the type and amount, the pore structure of the energy storage carbon material can be precisely controlled.

[0042] In some embodiments, the initial mechanical acid permeation temperature is 60°C to 150°C, and the time is 1 hour to 6 hours; The compaction gap of a multi-stage roller compactor decreases progressively. When three roller compactors are used, the compaction gap of the first stage is 10mm, the compaction gap of the second stage is 6mm, and the compaction gap of the third stage is 2mm.

[0043] In this embodiment, the choice of temperature affects the viscosity and reactivity of the acid solution. Increasing the temperature reduces the acid viscosity, accelerates the molecular diffusion rate, and promotes the penetration of the acid into the material. It also accelerates the initial reaction between the acid and the functional groups on the material surface. However, excessively high temperatures may lead to excessive decomposition of the acid or excessive oxidation of the material surface, while also reducing the material's viscosity. The processing time determines the degree of contact between the acid and the material. Too short a time results in insufficient penetration, while too long a time may cause unnecessary side reactions. The thermal and mechanical energy provided by heating and stirring allows the inorganic oxygen-containing acid solution to overcome the surface tension and internal pore resistance of the material, gradually wetting and penetrating the shallow pores of the material, laying the foundation for deeper penetration during subsequent multi-stage compaction.

[0044] In this embodiment, the progressively decreasing gap design subjectes the material to gradually increasing extrusion and shear forces at each stage. The first stage primarily focuses on initial compaction and crushing, the second stage on extrusion penetration, and the third stage on deep extrusion and thinning. Through progressively increasing mechanical stress, the acid adhering to the surface of the initially penetrating material is continuously extruded into the micropores and interlayer structure within the material. Simultaneously, shearing forces cause plastic deformation and interlayer delamination, achieving a uniform depth distribution of the acid within the material and ensuring the consistency of the pore-forming reaction during subsequent carbon activation.

[0045] In some embodiments, the temperature for medium-temperature carbonization is 160℃~300℃, and the carbonization time is 1h~12h; The activation temperature is 400℃~600℃, and the holding time is 10min~60min; Acid recovery is achieved by using six or more water washing tanks filled with activating material in series for gradient acid recovery and gradient washing. After washing, the carbon slurry is filtered to remove surface water while retaining adsorbed water inside the carbon.

[0046] In this embodiment, medium-temperature carbonization gradually pyrolyzes the organic components in the high-carbon-content material at a lower temperature, releasing small-molecule volatile substances. Simultaneously, it partially decomposes or transforms inorganic oxyacids into intermediate species with activation activity, forming a preliminary carbon skeleton structure. Too low a temperature or too short a time will result in incomplete pyrolysis, with excessive residual organic components affecting subsequent activation. Too high a temperature or too long a time may lead to excessive shrinkage of the carbon skeleton, which is detrimental to subsequent pore formation. By controlling the pyrolysis process, the material is transformed into a carbon intermediate with certain mechanical strength and a porous structure, while simultaneously preparing active sites for subsequent activation reactions.

[0047] Activation is the core step in pore formation. Within this temperature range, inorganic oxyacids or their decomposition products react chemically with the carbon skeleton, forming a porous structure by etching carbon atoms. Too low a temperature results in a slow activation reaction rate and insufficient pore formation; too high a temperature may lead to over-ablation of the carbon skeleton and collapse of the pore structure. Controlling the holding time is equally crucial; insufficient time leads to incomplete pore formation, while excessive time may result in over-activation. Utilizing the oxidative etching effect of inorganic oxyacids at high temperatures, some carbon atoms in the carbon skeleton are selectively consumed, forming micropores and mesopores. Simultaneously, some acid is reduced or decomposed into gas and escapes, leaving pore channels.

[0048] Gradient acid recovery utilizes the principle of countercurrent washing, adding clean water from the last tank and sequentially flowing through each preceding tank. This creates a concentration gradient with the free acid in the activated material, causing the acid to diffuse from high-concentration areas to low-concentration areas and be carried away by the clean water, thus achieving gradual acid recovery and concentration. Gradient washing involves multi-stage series washing, where the activated material comes into contact with washing water of different concentrations in each tank, gradually reducing the residual acid content. After washing, the carbon slurry is filtered to remove surface water, but retains the water adsorbed in the internal pores of the carbon, thus obtaining a wet carbon precursor. Gradient washing achieves full recovery and reuse of acid, reducing production costs and environmental pollution. Simultaneously, the intentional retention of adsorbed water within the carbon provides the gas source needed for self-activation in subsequent wet carbon heat treatment steps, enabling pore reconstruction without the need for additional active gas introduction.

[0049] In some embodiments, the high-temperature relatively sealed environment is a slightly positive pressure environment, with a specific exhaust port. During the reaction process, excess gas is discharged from the exhaust port, and the slightly positive pressure of the high-temperature relatively sealed environment is maintained. The heat treatment holding time is 10 min to 60 min.

[0050] In this embodiment, a slightly positive pressure environment refers to a state where the pressure inside the reaction vessel is slightly higher than the external atmospheric pressure. This prevents external air from entering the vessel and avoids oxidation of the carbon material with oxygen at high temperatures. Simultaneously, it maintains a certain concentration and pressure of the atmosphere released by the wet carbon precursor within the vessel, forming a highly active, self-activating atmosphere. A specific exhaust port refers to a controllable exhaust channel on the vessel, the opening of which is adjustable, used to discharge gas from the exhaust port during the reaction process.

[0051] The activation atmosphere primarily originates from the vaporization of wet carbon precursors at high temperatures, while volatile gases arise from the vaporization reaction products of the carbon skeleton and water molecules, including carbon monoxide, hydrogen, and small amounts of methane. By controlling the opening of the exhaust port, a dynamic balance is achieved between the gas generation rate and the exhaust rate within the container, thereby maintaining a slightly positive pressure environment. The holding time for high-temperature heat treatment can be selected within the range of 10 to 60 minutes. If the holding time is too short, the reaction between the atmosphere and the carbon skeleton will be insufficient, resulting in limited pore reconstruction; if the holding time is too long, it may lead to excessive ablation of the carbon skeleton, collapse of the pore structure, and an increase in macropores.

[0052] In this embodiment, the volatiles and moisture inside the wet carbon precursor are instantly vaporized during rapid heating, forming a local high-pressure environment in the micropores of the material. The atmosphere reacts with the carbon skeleton through vaporization, which on the one hand expands and connects the existing pores, and on the other hand, consumes some carbon atoms through the reaction to achieve densification. At the same time, the gas generated by the reaction is discharged from the exhaust port to maintain a slightly positive pressure environment to ensure that the reaction continues to proceed stably.

[0053] In some embodiments, the alkaline washing uses a sodium hydroxide solution with a mass concentration of 1% to 5%, the mass of the added sodium hydroxide solution is 3 to 6 times that of the heat-treated material, the alkaline washing temperature is 70°C to 100°C, and the alkaline washing time is 0.5h to 4h. The washing endpoint of alkali washing is when the pH of the filtered water is 8-10.

[0054] In this embodiment, sodium hydroxide neutralizes acidic impurities in the heat-treated material, while simultaneously dissolving ash components such as silica and some oxygen-containing functional groups remaining on the surface of amorphous carbon. If the alkali concentration is too low, its dissolving power is insufficient, making it difficult to effectively remove impurities; if the concentration is too high, it may cause excessive etching of the carbon skeleton, destroying the established porous structure. The choice of alkali dosage and temperature also affects the alkali washing efficiency. Insufficient dosage or too low temperature will lead to incomplete reaction, while excessive dosage or too high temperature will increase the burden on subsequent alkali washing and may cause carbon material loss. Controlling the alkali washing time requires ensuring sufficient contact and reaction between the alkali and impurities. Too short a time will result in incomplete impurity removal, while too long a time may cause unnecessary carbon loss. Utilizing the strong alkalinity and dissolving power of sodium hydroxide, non-carbon impurities generated during heat treatment are converted into soluble salts through a chemical reaction, thereby separating them from the carbon material and improving the purity of the carbon material.

[0055] In this embodiment, alkali washing refers to repeatedly washing the carbon material after alkali washing with clean water to remove free alkali residue on the surface and pores of the carbon material. The endpoint of washing is determined by the pH value of the filtered water. When the pH drops to the range of 8 to 10, it indicates that most of the free alkali has been removed and the residual alkali level is acceptable. If the pH is too high, it indicates that there is a lot of alkali residue, which may affect the subsequent pickling effect and lead to excessive alkali content in the final product; if the pH is too low, it may lead to over-washing, wasting water resources and prolonging the process time. Washing with clean water dilutes and removes the free alkali residue on the surface and pores of the carbon material, making the carbon material present a weakly alkaline environment, providing suitable starting conditions for the subsequent pickling step, and avoiding violent neutralization reaction between the alkali and the subsequently added acid, which could cause local overheating or waste of acid.

[0056] In some embodiments, pickling uses a hydrochloric acid solution with a mass concentration of 1% to 10%, the mass of the hydrochloric acid solution added is 3 to 6 times that of the heat-treated material, the pickling temperature is 70°C to 95°C, and the pickling time is 0.5h to 4h. The washing endpoint for acid washing is when the pH of the filtered water is greater than 6.

[0057] In this embodiment, hydrochloric acid neutralizes the residual alkaline solution in the carbon material after alkaline washing, and simultaneously dissolves inorganic impurities such as metal oxides and carbonates that may be present in the carbon material. These impurities mainly originate from minerals carried by the raw materials themselves or metal compounds formed during heat treatment. If the hydrochloric acid concentration is too low, its dissolving power is insufficient, making it difficult to effectively remove metal impurities; if the concentration is too high, it may cause excessive corrosion to the carbon skeleton, damaging the pore structure. The choice of hydrochloric acid dosage and temperature directly affects the pickling efficiency. Insufficient dosage or too low temperature will lead to incomplete reaction and incomplete impurity removal; excessive dosage or too high temperature will increase the burden of subsequent acid washing and may cause carbon material loss. The pickling time must be controlled to ensure sufficient contact and reaction between the hydrochloric acid and impurities. Too short a time will result in incomplete dissolution of impurities, while too long a time may cause unnecessary carbon loss or changes in the pore structure. Utilizing the strong acidity and dissolving power of hydrochloric acid for metal compounds, the residual alkaline solution after alkaline washing is neutralized through a chemical reaction, and impurities such as metal oxides are converted into soluble chlorides, thereby separating them from the carbon material and further improving the purity of the carbon material.

[0058] In this embodiment, acid washing refers to repeatedly washing the acid-washed carbon material with clean water to remove free acid and dissolved metal ions remaining on the surface and in the pores of the carbon material. The endpoint of the washing is determined by the pH value of the filtered water. When the pH is greater than 6, it indicates that most of the free acid and acidic salts have been removed, and the carbon material is close to neutral. If the pH is too low, it indicates that there is a lot of residual acid, which may result in an acidic final product, affecting its electrochemical stability and cycle life in energy storage devices. If the pH is too high, it may lead to over-washing, wasting water resources and prolonging the process time. Washing with clean water dilutes and removes the free acid and dissolved metal ions on the surface and in the pores of the carbon material, making the carbon material present a near-neutral environment. This avoids the adverse effects of residual acid or metal ions on the subsequent high-temperature fine treatment process, while ensuring that the final product has high purity and good chemical stability.

[0059] In some embodiments, the inert atmosphere is at least one of nitrogen and helium, the fine treatment temperature is 600°C to 1200°C, and the fine treatment time is 0.5h to 3h.

[0060] In this embodiment, an inert atmosphere prevents the carbon material from oxidizing with oxygen in the air during the high-temperature finishing process, thus avoiding carbon skeleton ablation and pore structure damage. Nitrogen is widely available and inexpensive, making it a commonly used inert protective gas; helium is chemically more stable and suitable for applications requiring higher atmosphere purity. The finishing temperature can be selected from 600℃ to 1200℃, and the finishing time can be selected from 0.5 hours to 3 hours. Finishing can further repair structural defects in the carbon skeleton, making the carbon layers more orderly, improving the graphitization degree and conductivity of the carbon material, while stabilizing the formed pore structure and preventing it from collapsing during subsequent use. If the temperature is too low or the time is too short, the structural repair will be insufficient, and the improvement in conductivity will be limited; if the temperature is too high or the time is too long, it may lead to excessive pore shrinkage, resulting in a decrease in specific surface area and pore volume.

[0061] In this embodiment, under a high-temperature inert atmosphere, carbon atoms gain sufficient energy to rearrange and migrate, transforming the disordered carbon layer structure towards an ordered one, while eliminating dangling bonds and defect sites in the carbon skeleton, thereby improving the conductivity and structural stability of the carbon material.

[0062] In some embodiments, a high-performance energy storage carbon material is also provided, which is the high-performance energy storage carbon material prepared by the aforementioned method steps.

[0063] The pore size distribution of the energy storage carbon material was calculated using a DFT model based on the nitrogen adsorption isotherm. The pore volume percentage of microporosity (0-3 nm) was ≥70%, the pore volume percentage of macroporosity (greater than 10 nm) was ≤10%, and the pore volume was ≥0.6 cm³. 3 / g, with a specific surface area of ​​1000m² / g to 2500m² / g and an average pore size of 1nm to 10nm.

[0064] In this embodiment, the nitrogen adsorption isotherm refers to the curve obtained by measuring the amount of nitrogen adsorbed on the surface of carbon material at different relative pressures under constant temperature, which can reflect the porosity characteristics of the material.

[0065] The DFT model, or density functional theory model, can extract pore size distribution information from nitrogen adsorption isotherms. The pore size distribution calculated using this model shows that the microporosity of the energy storage carbon material is at least 70% in the pore volume range of 0 to 3 nanometers, the macroporosity (greater than 10 nanometers) is at least 10%, the pore volume is at least 0.6 cubic centimeters per gram, the specific surface area is 1000 square meters per gram to 2500 square meters per gram, and the average pore size is 1 to 10 nanometers.

[0066] High microporosity signifies abundant charge storage sites, which is beneficial for increasing the capacity of energy storage devices; low macroporosity indicates a concentrated pore structure, avoiding the dilution of volumetric energy density by ineffective spaces; high pore volume and high specific surface area provide ample electrode-electrolyte interface, which is beneficial for ion adsorption and charge storage; a moderate average pore size balances the requirements of rapid ion transport and charge storage. Through nitrogen adsorption testing and DFT model analysis, the pore structure of the energy storage carbon material was quantitatively characterized, verifying its excellent pore structure characteristics of high microporosity, high pore volume, and high specific surface area, which can meet the requirements of high-performance energy storage devices for electrode materials.

[0067] Unlike existing technologies, the above technical solution involves initial mechanical acid permeation of high-carbon content materials with inorganic oxygen-containing acid solutions in a highly dispersed mixing device to obtain a pre-permeable material. This material is then fully permeated by mechanical force through a multi-stage mill with progressively smaller milling gaps to obtain a permeable material. After being dispersed into random particles by a toothed mixer, the material undergoes medium-temperature carbonization, activation, acid recovery, washing, and dehydration to obtain a wet carbon precursor. The wet carbon precursor is then placed in a high-temperature, relatively enclosed environment for rapid heating and high-temperature heat treatment using the atmosphere it releases to obtain a heat-treated material. This material is then subjected to alkali washing, alkali washing, acid washing, acid washing, and drying to obtain a dried intermediate. Finally, after high-temperature treatment under an inert atmosphere, the material is pulverized, graded, and iron removed to obtain an energy storage carbon material. By using inorganic oxyacids in conjunction with multi-stage mechanical pretreatment to ensure uniform distribution of the activator, and utilizing the self-activation and pore-forming properties of the wet carbon at high temperatures, the residual contamination from external activators is avoided. The resulting energy storage carbon material has a uniform and highly reproducible pore structure, exhibiting excellent characteristics of high microporosity, high pore volume, and high specific surface area. It meets the requirements of high-capacity storage and rapid ion transport, and can significantly improve the energy density and power density of energy storage devices.

[0068] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0069] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods of various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0070] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification and drawings, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis, characterized in that, include: High-carbon content materials and inorganic oxygen-containing acid solutions are transported to a high-dispersion stirring and mixing equipment according to a preset ratio, and after preliminary mechanical acid infiltration, a preliminary infiltrated material is obtained; The initial permeation material is conveyed to a multi-stage roller mill, which includes two or more roller mills arranged sequentially along the conveying direction. The roller mill's rolling gap decreases step by step, and the material undergoes full permeation treatment under mechanical force to obtain permeation material. The permeate is fed into a toothed agitator and dispersed to obtain random particles; The random particles were sequentially subjected to medium-temperature carbonization, activation, acid recovery, washing, and dehydration to obtain a wet carbon precursor. The wet carbon precursor is placed in a high-temperature, relatively sealed environment and rapidly heated to 550°C~850°C within 0.5 hours. High-temperature heat treatment is carried out using the atmosphere released by the wet carbon precursor itself to obtain heat-treated material. The heat-treated material is subjected to alkali washing, alkali washing, acid washing, acid washing, and drying in sequence to obtain a dried intermediate. The dried intermediate was subjected to high-temperature treatment under an inert atmosphere, and then crushed, graded, and iron removed to obtain an energy storage carbon material.

2. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The high-carbon content material is selected from at least one of biomass materials, synthetic resins, starch, and petroleum coke; The biomass material is at least one of peach shell powder, apricot shell powder, palm kernel shell powder, peach kernel shell powder, coconut shell powder, wood chips, and bamboo chips; the synthetic resin is at least one of phenolic resin, polystyrene crosslinking resin, furfural resin, furan resin, and epoxy resin; and the petroleum coke is at least one of raw coke or pre-calcining coke.

3. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The inorganic oxyacid is at least one of sulfuric acid, nitric acid, or phosphoric acid; The sulfuric acid has a mass concentration of 1% to 80%, the nitric acid has a mass concentration of 1% to 70%, and the phosphoric acid has a mass concentration of 40% to 85%. In the mass ratio of the inorganic oxyacid to the high-carbon content material, the mass ratio of pure sulfuric acid to high-carbon content material is 0~1:1, the mass ratio of pure nitric acid to high-carbon content material is 0~1:1, and the mass ratio of pure phosphoric acid to high-carbon content material is 0.8~2.5:

1.

4. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The initial mechanical acid permeation temperature is 60℃~150℃, and the time is 1h~6h; The compaction gap of the multi-stage roller compactor decreases step by step. When three roller compactors are used, the compaction gap of the first stage is 10mm, the compaction gap of the second stage is 6mm, and the compaction gap of the third stage is 2mm.

5. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The temperature for medium-temperature carbonization is 160℃~300℃, and the carbonization time is 1h~12h; The activation temperature is 400℃~600℃, and the holding time is 10min~60min; The acid recovery process involves a series of six or more water washing tanks filled with activating material to perform gradient acid recovery and gradient washing. The washed carbon slurry is then filtered to remove surface water while retaining adsorbed water inside the carbon.

6. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The high-temperature relatively sealed environment is a slightly positive pressure environment, with a specific exhaust port. During the reaction, excess gas is discharged from the exhaust port, and the slightly positive pressure of the high-temperature relatively sealed environment is maintained. The heat treatment time is 10 min to 60 min.

7. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The alkaline washing uses a sodium hydroxide solution with a mass concentration of 1% to 5%, and the mass of the sodium hydroxide solution added is 3 to 6 times that of the heat-treated material. The alkaline washing temperature is 70℃ to 100℃, and the alkaline washing time is 0.5h to 4h. The washing endpoint of the alkali washing is when the pH of the filtered water is 8-10.

8. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The pickling process uses a hydrochloric acid solution with a mass concentration of 1% to 10%, and the mass of the hydrochloric acid solution added is 3 to 6 times that of the heat-treated material. The pickling temperature is 70℃ to 95℃, and the pickling time is 0.5h to 4h. The washing endpoint of the acid washing is when the pH of the filtered water is greater than 6.

9. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The inert atmosphere is at least one of nitrogen and helium, the fine treatment temperature is 600℃~1200℃, and the fine treatment time is 0.5h~3h.

10. The method for preparing high-performance energy storage carbon materials based on acid treatment and wet carbon pyrolysis according to claim 1, characterized in that, The energy storage carbon material has its pore size distribution calculated using a DFT model based on nitrogen adsorption isotherms. The pore volume percentage of microporosity (0-3 nm) is ≥70%, the pore volume percentage of macroporosity (greater than 10 nm) is ≤10%, and the pore volume is ≥0.6 cm³. 3 / g, with a specific surface area of ​​1000m² / g to 2500m² / g and an average pore size of 1nm to 10nm.