Method for preparing a porous carbon composite material with mesoporous structure

Abstract

The application provides a preparation method of a porous carbon composite material with a mesoporous structure and relates to the technical field of lithium ion battery negative materials.Carbon source, a pore-forming agent and a phosphorus-based flame retardant are mixed and formed, a precursor is prepared through first heat treatment by using a first activating gas, and then the precursor is mixed with an organic metal polymer and second heat treatment is performed by using a second activating gas to obtain the porous carbon composite material with the mesoporous structure.The application adopts step-by-step activation and hierarchical pore-forming technical means, a stable microporous matrix is first constructed, then deep etching is performed to form a mesoporous structure, and meanwhile, the uniform loading of metal components is realized, so that the problem that the pore volume and the tap density are difficult to be considered is effectively solved, the obtained material has high pore volume, high tap density and excellent conductivity, the structure is stable, the electron conduction is fast, and the rate performance and the cycle stability of a silicon-carbon negative electrode can be improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery anode material technology, and in particular to a method for preparing a mesoporous porous carbon composite material. Background Technology

[0002] Porous carbon is the core substrate material for silicon-carbon composites. Its pore volume, pore size, powder resistivity, and isotropic properties directly affect the interfacial impedance, active material loading, and structural compressive stability of the composite material. A well-designed pore structure can effectively buffer the volume deformation of the active material and optimize ion transport channels; excellent conductivity uniformity can reduce charge transport impedance. Meanwhile, porous carbon possesses high specific surface area, good structural stability, and tunable pore structure, making it promising for applications in energy storage electrodes, catalyst supports, and environmental adsorption.

[0003] Numerous existing technologies have focused on the modification of porous carbon. For example, patent application CN202311566243.7 discloses porous carbon and its preparation method, as well as silicon-carbon anode materials and their preparation methods. This technology uses biomass carbon sources as raw materials to prepare porous crude carbon through heat treatment, and then uses organic carbon sources combined with chemical vapor deposition to fill and seal the pores, thereby blocking the tiny pores inside the material. Although this approach can reduce the specific surface area of ​​the material and improve the first coulombic efficiency of the electrode, it does not achieve optimized improvement in the power performance of the material, and the obtained porous carbon has a low tap density, resulting in poor subsequent electrode processing and forming performance.

[0004] Therefore, it is urgent to solve the technical problem that tap density and pore volume are difficult to balance and mutually restrict each other in the existing porous carbon preparation process, which makes it difficult to improve power performance. Developing a porous carbon preparation technology with high pore volume and high tap density that meets the application requirements of silicon-carbon composite materials is a technical problem that needs to be solved at present. Summary of the Invention

[0005] This invention solves the technical problem of the mutual constraint between pore volume and tap density by first constructing a porous foundation through preliminary pore formation, then introducing organometallic materials after a first activation, and finally expanding the pores through a second activation.

[0006] First, a carbon source, pore-forming agent, and phosphorus-based flame retardant are mixed and molded to obtain a first intermediate. A first heat treatment is then performed under a first activation gas atmosphere. The pore-forming agent is uniformly distributed within the carbon-based precursor framework and then removed, forming initial micropores and steadily constructing the initial porous structure to ensure the material's inherent pore volume level. The phosphorus-based flame retardant decomposes upon heating to form a dense phosphorus-oxygen protective layer, inhibiting excessive ablation of the carbon framework, maintaining structural stability, and achieving in-situ phosphorus doping. The first activation completes the shaping of the carbon-based precursor framework and the construction of basic micropores. Subsequent addition of organometallic components does not interfere with the initial pore-forming and carbonization processes, avoiding damage to the pore structure. Simultaneously, the organometallic components can modify the surface morphology of carbon particles, reducing interparticle porosity and thus increasing the material's tap density. Finally, a second heat treatment is performed in a second activation gas atmosphere to further expand the pore volume and open pores, thereby achieving high pore volume while maintaining high tap density.

[0007] One objective of this invention is to provide a method for preparing a mesoporous porous carbon composite material, comprising the following steps: The carbon source, pore-forming agent and phosphorus-based flame retardant are mixed and then molded to obtain the first intermediate. The first intermediate was subjected to a first heat treatment in the atmosphere of the first activating gas to obtain the precursor material. The precursor material and the organometallic polymer are mixed and dried to obtain a second intermediate. The second intermediate is subjected to a second heat treatment in the atmosphere of the second activating gas to obtain the porous carbon composite material with the mesoporous structure.

[0008] Preferably, the carbon source comprises a glycosyl compound; The glycosyl compound includes at least one of glucose, sucrose, fructose, maltose, or starch.

[0009] Preferably, the pore-forming agent includes at least one of zinc acetate, zinc ethylhexanoate, zinc laurate, zinc oxalate, zinc basic stearate, zinc citrate, or zinc formate.

[0010] Preferably, the chemical activity of the first activating gas is higher than that of the second activating gas; The first activating gas includes water vapor and / or carbon dioxide; The second activating gas includes at least one of fluorine, chlorine, hydrogen, or oxygen.

[0011] Preferably, the mass ratio of the precursor material to the organometallic polymer is 100:10 to 30.

[0012] The organometallic polymer includes at least one of pentamethylcyclopentaenoic nickel, pentacarbonyl iron, dimethylplatinum dichloride, triphenylchromium, or ferrocene.

[0013] Preferably, the phosphorus-based flame retardant includes one of the following: phosphorus-based triaryl phosphate, trialkyl phosphate, resorcinol bis(diphenyl phosphate), tri(trimethylsilyl) phosphate, or tripolyphosphate. The mass ratio of the carbon source, phosphorus-based flame retardant, and pore-forming agent is 100:5-20:10-30.

[0014] Preferably, an amine crosslinking agent is also added when mixing the carbon source, pore-forming agent, and phosphorus-based flame retardant; The amine crosslinking agent includes at least one of diethylenetriamine, polyethylenepolyamine, ethylenediamine, hexamethylenediamine, butylenediamine, or diethylenetriamine; The mass ratio of the glycosyl compound, pore-forming agent, and amine crosslinking agent is 100:10-30:5-10.

[0015] Preferably, the first heat treatment includes heating the first intermediate to 1000-1400°C and introducing a first activation gas; The flow rate of the first activating gas is 100-500 ml / min, and the introduction time is 30-300 min; The second heat treatment includes heating the second intermediate to 900-1100°C and introducing a second activation gas; The flow rate of the second activating gas is 100-500 ml / min, and the introduction time is 30-300 min.

[0016] Preferably, after the precursor material is mixed with the organometallic polymer and before drying, it is further subjected to a densification treatment so that the organometallic polymer penetrates into the pores and surface depressions of the precursor material; The densification process includes at least one of vacuum extrusion, vacuum impregnation, or centrifugal impregnation.

[0017] The beneficial effects of this invention are: This invention solves the technical challenge of the mutual constraint between pore volume and tap density by employing a technique of first constructing a porous foundation through preliminary pore formation, introducing organometallic compounds after a first activation, and then expanding the pore channels through a second activation. First, a carbon source, a pore-forming agent, and a phosphorus-based flame retardant are mixed and molded to prepare a first intermediate. After a first heat treatment in an activation gas atmosphere, the pore-forming agent undergoes carbothermic reduction and vaporization to form primary micropores. The phosphorus-based flame retardant decomposes thermally to form a dense phosphorus-oxygen protective layer, inhibiting excessive ablation of the carbon skeleton, maintaining structural integrity, and introducing phosphorus doping in situ. Combined with the vapor-phase etching effect during the first heat treatment, the pore channels are initially connected, resulting in a structurally stable precursor material. Simultaneously, an organometallic component is introduced. Its metallic components can stably bond with the carbon matrix, modifying the carbon particle surface, optimizing the packing state to improve tap density, enhancing the material's conductivity, and without damaging the initial porous structure. The precursor material is mixed with an organometallic polymer to prepare a second intermediate. After a second heat treatment in a second activation gas atmosphere, the original micropores are further widened to form a mesoporous structure. The resulting material has a large pore volume and high tap density, which meets the application requirements of silicon-carbon anodes. Attached Figure Description

[0018] Figure 1 This is a SEM image of the mesoporous porous carbon composite material prepared in Example 8. Detailed Implementation

[0019] The present application will now be described in further detail with reference to embodiments. In the following description, certain specific details are included to provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments can be implemented without employing one or more of these specific details, but using other methods, components, materials, etc. Unless otherwise required by the present invention, the terms "comprising" and "including" should be interpreted in an open-ended, inclusive sense, meaning "including but not limited to". Throughout this specification, "an embodiment," "an embodiment," "a preferred embodiment," or "some embodiments" means that at least one embodiment includes a specific reference element, structure, or feature related to that embodiment. Therefore, the phrases "in an embodiment," "in an embodiment," "in a preferred embodiment," or "in some embodiments" appearing in different places throughout the specification do not necessarily all refer to the same embodiment. Furthermore, specific elements, structures, or features may be combined in one or more embodiments in any suitable manner.

[0020] This invention provides a method for preparing a mesoporous porous carbon composite material, comprising the following steps: S1. The carbon source, pore-forming agent and phosphorus-based flame retardant are mixed and then molded to obtain the first intermediate. S2. The first intermediate is subjected to a first heat treatment in the atmosphere of the first activating gas to obtain the precursor material; S3. Mix the precursor material and the organometallic polymer, and dry them to obtain the second intermediate; S4. The second intermediate is subjected to a second heat treatment in the atmosphere of the second activating gas to obtain the mesoporous porous carbon composite material.

[0021] In this invention, the carbon source serves as a precursor to the carbon matrix. After heat treatment, it is carbonized to form a stable and rigid carbon skeleton, thereby constructing a complete pore structure system for the material. This ensures the overall structural strength and stability of the material and provides an attachment substrate for organometallic loading and interfacial bonding. It is the main skeleton that directly constitutes the porous carbon composite material. The pore-forming agent is distributed within the carbon-based precursor framework and is vaporized and removed during the first activation heat treatment, generating a large number of initial micropores in situ within the material, thus constructing the basic porous structure. Simultaneously, the activated vapor-phase etching process connects adjacent pores, making the channels interconnected and stabilizing the material's basic porosity. The pore-forming agent only serves to create pores by occupying sites and does not participate in the carbon matrix reaction, effectively maintaining the overall structural stability of the carbon framework. Phosphorus-based flame retardants decompose during heat treatment, forming a dense phosphorus-oxygen protective layer that isolates the carbon skeleton from heat and oxygen erosion, inhibits excessive ablation of the carbon skeleton, and maintains the integrity of the carbon matrix structure. At the same time, in-situ doping of phosphorus is achieved, which optimizes the electronic conductivity of the carbon skeleton and improves the electrical conductivity and interface stability of the material.

[0022] The reaction atmosphere of the first heat treatment can promote the full decomposition and vaporization of the pore-forming agent, while generating a mild vapor-phase etching effect to open up the closed micropores and achieve initial connectivity of the pores. During this process, the phosphorus-based flame retardant plays a protective and doping role, further stabilizing the carbon skeleton structure, allowing the carbon source to be fully carbonized and shaped, and stabilizing and solidifying the early porous basic structure.

[0023] Introducing organometallic materials after a single activation heat treatment does not damage the already formed micropores and carbon skeleton. Furthermore, the organometallic materials are uniformly coated on the surface of the precursor material particles, effectively regulating the microstructure of the particles, making the particles more compact, reducing the gaps between particles, and increasing the tap density of the material.

[0024] During the secondary heat treatment of the second intermediate in the second activation gas atmosphere, the activation gas can deeply etch the internal pores of the material, further widening and interconnecting the original micropores formed in the first heat treatment to form a mesoporous structure, effectively improving the overall pore volume. At the same time, the organometallic polymer decomposes upon heating, and the active metal components are precipitated in situ and uniformly loaded on the carbon matrix and pore surface, firmly bonding with the carbon skeleton; the secondary activation atmosphere simultaneously modifies the carbon matrix interface, accelerating the electron conduction rate and enhancing electrical conductivity, ultimately giving the material both high pore volume and high tap density.

[0025] In a preferred embodiment of the present invention, the carbon source includes a glycosyl compound; The glycosyl compound includes at least one of glucose, sucrose, fructose, maltose, or starch.

[0026] In this invention, glucose, sucrose, fructose, maltose, or starch all possess good reactivity and carbonization properties, providing a stable carbon source basis for the preparation of porous carbon materials; their molecular structures are rich in active groups such as hydroxyl groups, which can react with amine crosslinking agents to form a structurally stable polymerization system, while providing binding sites for heteroatom doping.

[0027] In a preferred embodiment of the present invention, the pore-forming agent includes at least one of zinc acetate, zinc ethylhexanoate, zinc laurate, zinc oxalate, basic zinc stearate, zinc citrate, or zinc formate.

[0028] In this invention, zinc acetate, zinc ethylhexanoate, zinc laurate, zinc oxalate, basic zinc stearate, zinc citrate, or zinc formate all possess excellent thermal decomposition characteristics. They can gradually decompose, vaporize, and release during heat treatment, creating pores within the carbon matrix and forming a primary microporous structure, directly constructing a primary microporous structure within the carbon matrix. Simultaneously, these zinc salts exhibit mild decomposition and low residual impurities, effectively controlling the pore volume and pore size of the carbon matrix, preventing excessive collapse and sintering of the carbon skeleton, and contributing to improved material pore structure stability, active site loading, and overall conductivity.

[0029] In a preferred embodiment of the present invention, the chemical activity of the first activating gas is higher than that of the second activating gas; The first activating gas includes water vapor and / or carbon dioxide; The second activating gas includes at least one of fluorine, chlorine, hydrogen, or oxygen.

[0030] In this invention, chemical activity refers to the strength of the reaction between the gas and the carbon matrix under high-temperature activation conditions, including oxidation etching, carbon bond breaking, and framework erosion. The more vigorous the reaction and the more easily the carbon structure is destroyed, the higher the chemical activity.

[0031] The chemical activity of the first activating gas is higher than that of the second activating gas. The first activating gas is selected from water vapor and / or carbon dioxide, which has a relatively mild reaction activity. When used for the first heat treatment, it only lightly etches the carbon matrix, and the pore-forming agent decomposes and removes to construct uniform original micropores, realizing the initial connection of the pores. At the same time, it avoids excessive ablation and collapse of the carbon skeleton, thus constructing a stable basic carbon matrix.

[0032] The second activating gas contains at least one of fluorine, chlorine, hydrogen, or oxygen, and its overall chemical activity is lower than that of the first activating gas. Based on the initial formation of native micropores, directional deep etching can be achieved to effectively construct a mesoporous structure; at the same time, in-situ loading of metal active components is completed, and the carbon skeleton interface structure is optimized. The simultaneous in-situ loading of metal active components and optimization of carbon skeleton interface structure effectively enhance the structural stability and rate electrochemical performance of silicon-carbon anodes.

[0033] In a preferred embodiment of the present invention, the mass ratio of the precursor material to the organometallic polymer is 100:10 to 30.

[0034] In this invention, the mass ratio of the precursor material to the organometallic polymer is, for example, 100:10, 100:15, 100:20, 100:25, or 100:30.

[0035] In a preferred embodiment of the present invention, the organometallic polymer includes at least one of pentamethylcyclopentanetetracarbonylnickel, pentacarbonylferric, dimethyldichloroplatinum, triphenylchromium, or ferrocene.

[0036] In this invention, pentamethylcyclopentaenoic nickel, pentacarbonyl iron, dimethyl dichloride, triphenyl chromium, and ferrocene all have controllable thermal decomposition characteristics, enabling them to uniformly decompose and precipitate metal active components in situ during heat treatment, uniformly loading them onto the carbon matrix framework and the inner walls of the pores. The mass ratio of the precursor material to the organometallic polymer is 100:10 to 30, with preferred ratios of 100:10, 100:20, and 100:30. This ratio ensures that the organometallic polymer is uniformly dispersed in the precursor channels and on the surface. When the mass ratio of precursor to organometallic polymer is greater than 100:10, the amount of organometallic polymer doping is insufficient, making it difficult to fully exert the effects of metal component modification, interface regulation, and pore formation. The carbon skeleton modification effect is limited, and the improvement of the material's electrochemical performance is not significant. When the mass ratio of precursor to organometallic polymer is less than 100:30, the organometallic polymer content is too high, which easily leads to agglomeration and accumulation, blocking the precursor channels, causing a decrease in pore volume and specific surface area, and at the same time causing the skeleton structure to become disordered, reducing the overall structural stability of the silicon-carbon anode.

[0037] Meanwhile, organometallic polymers can tightly bind with the carbon matrix, strengthen the interfacial connection strength, and accelerate the electron conduction speed; they can also form more effective active sites on the pore surface, improve the pore wall condition, and simultaneously complete the formation of multi-level pore structures and the loading of metal components, taking into account both the material's conductivity and the overall structural robustness.

[0038] In a preferred embodiment of the present invention, the phosphorus-based flame retardant includes one of phosphorus-based triaryl phosphate, trialkyl phosphate, resorcinol bis(diphenyl phosphate), tri(trimethylsilyl) phosphate, or tripolyphosphate.

[0039] In this invention, phosphorus-based triaryl phosphates, trialkyl phosphates, resorcinol bis(diphenyl phosphate), tri(trimethylsilyl) phosphate, or tripolyphosphates all possess excellent flame-retardant properties. Upon thermal decomposition, they form a dense phosphorus-oxygen protective layer, isolating the carbon matrix from thermo-oxidative corrosion and preventing excessive ablation during heat treatment, thus maintaining the integrity and stability of the carbon skeleton. At high temperatures, phosphorus is directly incorporated into the carbon matrix, increasing surface active sites and reducing electron conduction resistance. These additives can synergistically work with carbon sources and pore-forming agents, assisting in the decomposition and removal of pore-forming agents and optimizing pore structure, while also improving the carbonization and forming effect of the carbon source, thus strengthening the overall structure and conductivity of the carbon matrix.

[0040] The mass ratio of the carbon source, phosphorus-based flame retardant, and pore-forming agent is 100:5-20:10-30.

[0041] In this invention, the mass ratio of carbon source, phosphorus-based flame retardant and pore-forming agent is, for example, 100:5:10, 100:12:20, or 100:20:30.

[0042] In a preferred embodiment of the present invention, an amine crosslinking agent is also added when mixing the carbon source, pore-forming agent and phosphorus-based flame retardant; The amine crosslinking agent includes at least one of diethylenetriamine, polyethylenepolyamine, ethylenediamine, hexamethylenediamine, butylenediamine, or diethylenetriamine; In this invention, diethylenetriamine, polyethylenetriamine, ethylenediamine, hexamethylenediamine, butanediamine, or diethylenetriamine all contain a large number of active amino functional groups, which can undergo cross-linking condensation reactions with hydroxyl groups on the surface of glycosyl carbon sources to construct a three-dimensional network precursor system with a dense structure and uniform cross-linking degree, thereby enhancing the overall strength of the precursor skeleton and inhibiting the shrinkage and collapse of the carbon structure during heat treatment.

[0043] The mass ratio of the glycosyl compound, pore-forming agent, and amine crosslinking agent is 100:10-30:5-10.

[0044] In this invention, the mass ratio of the glycosyl compound, the pore-forming agent, and the amine crosslinking agent is, for example, 100:10:5, 100:20:8, or 100:30:10.

[0045] In a preferred embodiment of the present invention, the molding process includes spray drying.

[0046] Spray drying allows the mixture to solidify and form quickly, with uniform particle dispersion, ensuring that the pore-forming agent and organometallic polymer components are evenly distributed in the carbon precursor, thus improving the uniformity and stability of heat treatment pore formation and element doping modification.

[0047] In a preferred embodiment of the present invention, the temperature of the first heat treatment is 1000-1400°C; The flow rate of the first activating gas is 100–500 ml / min; The first activating gas is introduced for 30 to 300 minutes; The temperature of the second heat treatment is 900–1100°C; The flow rate of the second activating gas is 100–500 ml / min; The second activating gas is introduced for 30 to 300 minutes.

[0048] In this invention, the first heat treatment temperature is set at 1000–1400°C. This temperature range ensures that the pore-forming agent undergoes a complete carbothermic reduction reaction and is vaporized and removed, while simultaneously achieving in-situ embedding of heteroatoms into the carbon framework and initial connectivity of the original micropores. This temperature range is appropriately matched to the etching activity of the first activating gas, ensuring complete carbonization of the carbon source and the formation of a structurally stable carbon matrix, while preventing excessive ablation of the carbon framework and pore collapse due to excessively high temperatures; conversely, excessively low temperatures result in incomplete removal of the pore-forming agent and uneven heteroatom doping, affecting subsequent processes.

[0049] The first activation gas flow rate is 100-500 ml / min, which can ensure a uniform activation atmosphere and stable reaction. If the flow rate is too low, the gas diffusion will be insufficient and the activation will be uneven. If the flow rate is too high, it will easily cause excessive local scouring and structural damage.

[0050] The initial activation gas introduction time is set to 30–300 min, which can achieve the synergistic completion of complete removal of pore-forming agent, initial micropore connectivity, and uniform heteroatom doping. If the time is too short, activation will be insufficient and pore volume will be low; if the time is too long, over-etching will occur and structural strength will decrease. This time range can achieve the optimal balance between carbon matrix formation, micropore construction, and heteroatom doping, ensuring the comprehensive performance of the precursor material.

[0051] The second heat treatment temperature is set at 900–1100℃, lower than the first heat treatment temperature, to accommodate the higher chemical activity of the second activating gas and simultaneously complete micropore widening, mesopore construction, and metal component loading. This temperature allows for complete pyrolysis of the organometallic polymer, ensuring uniform precipitation and dispersion of the metal component; it also prevents high-temperature sintering of the carbon skeleton, mesopore damage, and metal particle aggregation. Temperatures that are too low will result in incomplete decomposition of organic matter, insufficient metal loading, difficulty in effectively expanding micropores, disordered mesopore structures, and ultimately reduced electrochemical performance of the material.

[0052] The flow rate of the second activating gas is 100–500 ml / min, which can match the high activity of the second activating gas to broaden the original micropores and generate mesoporous structures. Too low a flow rate will result in insufficient etching intensity and insufficient micropore broadening, making it impossible to form a qualified mesoporous structure; too high a flow rate will result in over-etching, leading to disordered pore expansion, damage to the carbon skeleton, and oxidation and loss of metal components, affecting the number of active sites and conductivity of the material.

[0053] The second activation gas introduction time is set to 30-300 min to fully improve the mesopore size and distribution, ensure uniform loading of metal components, and complete the interface modification of the carbon matrix.

[0054] In a preferred embodiment of the present invention, after the precursor material is mixed with the organometallic polymer and before drying, it is further subjected to a densification treatment so that the organometallic polymer penetrates into the pores and surface depressions of the precursor material. The densification process includes at least one of vacuum extrusion, vacuum impregnation, or centrifugal impregnation.

[0055] In this invention, at least one of vacuum extrusion, vacuum impregnation, or centrifugal impregnation is employed to ensure that the organometallic polymer fully penetrates the internal pores and surface depressions of the precursor material, rather than simply adhering to the outer layer of the particles. This process enhances the adhesion between the polymer and the carbon matrix. During subsequent heat treatment, the metal component can uniformly precipitate and bond within the pores and on the surface, avoiding uneven surface loading and localized agglomeration, further strengthening the interfacial bonding effect with the carbon matrix, and improving the material's electronic conductivity and interfacial electrical stability.

[0056] In a preferred embodiment of the present invention, the method for preparing a mesoporous porous carbon composite material specifically includes: S1, Preparation of the first intermediate According to the mass ratio of sugar-based compound: phosphorus-based flame retardant: pore-forming agent: amine crosslinking agent = 100: 5~20: 10~30: 5~10, the sugar-based compound, phosphorus-based flame retardant and pore-forming agent are added to an organic solvent and stirred until uniformly dispersed. Then, an amine crosslinking agent solution is added and mixed evenly. After spray drying, the first intermediate material is obtained.

[0057] S2, Preparation of precursor materials The first intermediate material is placed in a high-temperature device and heated to 1000-1400℃. Carbon dioxide and / or water vapor are introduced as activation gases at a flow rate of 100-500 mL / min for 30-300 min to obtain the precursor material.

[0058] S3, Preparation of the second intermediate The precursor material and organometallic polymer are mixed evenly according to a mass ratio of 100:10~30. The mixture is then added to an extruder for vacuuming, extrusion, heating and drying to obtain the second intermediate.

[0059] S4, Preparation of porous carbon composite materials The second intermediate is placed in a high-temperature device and heated to 900–1100°C. At least one of fluorine, chlorine, hydrogen, or oxygen is introduced as an active gas at a flow rate of 100–500 mL / min. The mixture is activated for 30–300 min. After the second activation is completed, a porous carbon composite material is obtained.

[0060] Example 1 S1. Mix 100g glucose, 20g tripolyphosphate and 20g zinc acetate evenly, and then spray dry to form the first intermediate.

[0061] S2. Place the first intermediate in a high-temperature device, heat it to 1200℃, and introduce carbon dioxide at a flow rate of 300mL / min to activate it for 150min to obtain the precursor material.

[0062] S3. Mix 100g of precursor material with 20g of ferrocene evenly and dry to obtain the second intermediate.

[0063] S4. The second intermediate is heated to 1000℃, and fluorine gas is introduced at a flow rate of 300mL / min for 150min to obtain a mesoporous porous carbon composite material.

[0064] Example 2 S1. Mix 100g glucose, 5g triaryl phosphate and 10g zinc acetate evenly, and spray dry to form the first intermediate.

[0065] S2. Heat the first intermediate to 1000℃, introduce carbon dioxide at a flow rate of 100mL / min, and activate for 30min to obtain the precursor material.

[0066] S3. Mix 100g of precursor material with 10g of pentamethylcyclopentanetetracarbonyl nickel evenly and dry to obtain the second intermediate.

[0067] S4. The second intermediate is heated to 900℃, and chlorine gas is introduced at a flow rate of 100mL / min for 30min to obtain a mesoporous porous carbon composite material.

[0068] Example 3 The difference from Example 2 is as follows: 100g of sucrose is used as the carbon source, 30g of zinc oxalate is used as the pore-forming agent, and 10g of diethylenetriamine is added; the first heat treatment temperature in step S2 is 1400℃, water vapor is introduced at a flow rate of 500mL / min, and activation is carried out for 300min; the amount of organometallic polymer added in step S3 is 30g; the second heat treatment temperature in step S4 is 1100℃, oxygen is introduced at a flow rate of 500mL / min, and activation is carried out for 300min.

[0069] Example 4 The difference from Example 2 is as follows: in step S1, 100g of fructose is used as the carbon source, 20g of zinc laurate is used as the pore-forming agent, and 12g of resorcinol bis(diphenyl phosphate) and 8g of ethylenediamine are added; in step S2, a mixture of water vapor and carbon dioxide is used as the activation gas; in step S3, 20g of pentacarbonyl iron is used; and in step S4, hydrogen is used as the activation gas.

[0070] Example 5 The difference from Example 1 is that: in step S1, 100g of starch is used as the carbon source and 20g of zinc citrate is used as the pore-forming agent; in step S3, vacuum impregnation densification treatment is added after mixing; and in step S4, a mixture of fluorine and chlorine gas is used as the activation gas.

[0071] Example 6 The difference from Example 2 is as follows: in step S1, 100g of maltose is used as the carbon source, 15g of zinc formate is used as the pore-forming agent, and 10g of tris(trimethylsilyl) phosphate is added; in step S2, water vapor is introduced at a flow rate of 200mL / min and activated for 60min; in step S3, 15g of triphenylchromium is used; in step S4, the second heat treatment temperature is 950℃, hydrogen is introduced at a flow rate of 200mL / min, and activated for 60min.

[0072] Example 7 The difference from Example 3 is as follows: in step S1, 100g of glucose is used as the carbon source, 25g of basic zinc stearate is used as the pore-forming agent, and 9g of hexamethylenediamine is added; in step S2, the first heat treatment temperature is 1300℃, the carbon dioxide flow rate is 400mL / min, and the activation time is 200min; in step S3, the amount of organometallic polymer added is 25g; in step S4, oxygen is introduced at a flow rate of 400mL / min and the activation time is 200min.

[0073] Example 8 The difference from Example 4 is as follows: in step S1, 100g of glucose is used as the carbon source, 20g of zinc acetate is used as the pore-forming agent, and 10g of triaryl phosphate matrix and 8g of diethylenetriamine solution are added; in step S3, 20g of pentamethylcyclopentanetetracarbonyl nickel is used, and vacuum extrusion densification treatment is added; in step S4, chlorine is used as the activation gas.

[0074] Example 9 The difference from Example 1 is as follows: in step S1, 100g of fructose is used as the carbon source and 10g of zinc laurate is used as the pore-forming agent; in step S2, the activation time is shortened to 30min; in step S3, the amount of organometallic polymer added is 10g; in step S4, the second heat treatment temperature is 900℃ and the activation time is 30min.

[0075] Example 10 The difference from Example 1 is as follows: in step S1, 100g of starch is used as the carbon source and 30g of zinc citrate is used as the pore-forming agent; in step S2, the first heat treatment temperature is 1400℃, water vapor is introduced at a flow rate of 500mL / min, and activation is carried out for 300min; in step S3, the amount of organometallic polymer added is 30g; in step S4, the second heat treatment temperature is 1100℃, hydrogen is introduced at a flow rate of 500mL / min, and activation is carried out for 300min.

[0076] Comparative Example 1 S1. Mix 100g sucrose, 30g zinc ethylhexanoate and 10g butanediamine evenly, and then spray dry to form the first intermediate.

[0077] S2. The first intermediate is heated to 1200℃, and a mixture of water vapor and carbon dioxide is introduced at a flow rate of 300mL / min for 150min for the first heat treatment to obtain the precursor material.

[0078] S3. Mix 100g of precursor material with 20g of pentamethylcyclopentanetetracarbonyl nickel evenly, densify by vacuum extrusion, and then dry to obtain the second intermediate.

[0079] S4. The second intermediate is heated to 1000℃, and chlorine gas is introduced at a flow rate of 300mL / min for 150min for a second heat treatment to obtain carbon material.

[0080] Compared to Example 8, this comparative example did not include a phosphorus-based flame retardant, but all other steps were the same. The lack of phosphorus doping modification resulted in reduced electronic conductivity, insufficient structural stability, and a significant decrease in electrochemical performance and cycle stability.

[0081] Comparative Example 2 S1. Mix 100g sucrose, 20g tripolyphosphate and 10g butanediamine evenly, and then spray dry to form the first intermediate.

[0082] S2. The first intermediate is heated to 1200℃, and a mixture of water vapor and carbon dioxide is introduced at a flow rate of 300mL / min for 150min for the first heat treatment to obtain the precursor material.

[0083] S3. Mix 100g of precursor material with 20g of pentamethylcyclopentanetetracarbonyl nickel evenly, densify by vacuum extrusion, and then dry to obtain the second intermediate.

[0084] S4. The second intermediate is heated to 1000℃, and chlorine gas is introduced at a flow rate of 300mL / min for 150min for a second heat treatment to obtain carbon material.

[0085] Compared to Example 8, this comparative example did not include a pore-forming agent, but all other steps were the same. The material failed to form a uniform pore structure, resulting in reduced pore volume and specific surface area, hindered lithium-ion transport, and significantly deteriorated electrochemical performance.

[0086] Comparative Example 3 S1. Mix 100g sucrose, 20g tripolyphosphate, 30g zinc ethylhexanoate and 10g butanediamine evenly, and then spray dry to form the first intermediate.

[0087] S2. The first intermediate is heated to 1200℃, and a mixture of water vapor and carbon dioxide is introduced at a flow rate of 300mL / min for 150min for the first heat treatment to obtain the precursor material.

[0088] S3. The precursor material does not contain pentamethylcyclopentanetetracarbonyl nickel, and is directly dried without densification treatment.

[0089] S4. Heat the precursor to 1000℃, introduce chlorine gas at a flow rate of 300mL / min, and perform a second heat treatment for 150min to obtain carbon material.

[0090] Compared to Example 8, this comparative example did not introduce an organometallic polymer component, but the remaining steps were the same. The material lacks metal active sites and conductivity enhancement, resulting in low electronic conductivity, loose particle packing, insufficient tap density, and significantly deteriorated electrochemical performance.

[0091] Comparative Example 4 S1. Glucose and zinc acetate are mixed evenly and then spray-dried to form the first intermediate.

[0092] S2. Heat the first intermediate to 1200℃, introduce carbon dioxide at a flow rate of 300mL / min, and perform heat treatment for 150min to directly obtain carbon material.

[0093] S3. No mixing of precursors and organometallic compounds, and no second heat treatment.

[0094] Compared with Example 8, this comparative example omits the second heat treatment and secondary activation steps, while maintaining the same other conditions. Due to the lack of secondary deep etching, the material only forms a basic microporous structure and cannot construct a through-pore system. This results in low pore volume, hindered ion transport, and decreased rate performance and structural stability.

[0095] Comparative Example 5 S1. After mixing glucose and zinc acetate, skip the molding process and proceed directly to heat treatment.

[0096] S2. Heat to 1200℃ and introduce carbon dioxide at a flow rate of 300mL / min for 150min for the first heat treatment.

[0097] S3 is the same as step S3 in Example 1.

[0098] S4 is the same as step S4 in Example 1.

[0099] Compared with Example 8, this comparative example omits the spray drying molding step, resulting in uneven material dispersion, severe particle agglomeration, and uneven distribution of pore-forming agent and organometallic, leading to disordered pore structure and low tap density.

[0100] Performance testing 1. Scanning electron microscopy (SEM) test: Figure 1 The image shows a SEM diagram of the mesoporous porous carbon composite material prepared in Example 8. As can be seen from the image, it exhibits a secondary spherical structure with a particle size between 1 micrometer and 5 micrometers and a uniform size distribution.

[0101] 2. Physicochemical property testing The physicochemical properties of the porous carbon composite materials prepared in Examples 1-10 and the comparative examples were tested respectively. The pore size, effective pore volume, and specific surface area of ​​each porous carbon were tested according to the national standards GB / T-38949-2020 "Determination of Pore Size of Porous Membranes - Standard Particle Method" and GB / T-7702.20-2008 "Detection of Pore Volume of Coal-based Activated Carbon". The tap density was tested according to GB / T-38823-2020 "Silicon Carbon". The resistivity of the porous carbon powder was then tested using a four-probe tester. The crushing strength was tested by using a compaction density meter to slowly increase the pressure on the porous carbon particles, recording the pressure until a sudden, sharp drop occurred; the maximum pressure recorded was the crushing strength. The test results are shown in Table 1. 3. Button cell battery test The coin cell was prepared according to the following method: The negative electrode active material, binder, conductive agent, and solvent were mixed (in a ratio of 70g:15g:15g:300mL), stirred to form a slurry, and then coated onto copper foil. After drying and pressing, the negative electrode sheet was obtained. The binder used was LA136D, the conductive agent was SP (conductive carbon black), and the solvent was NMP. The electrolyte was a 1mol / L solution with LiPF6 as the electrolyte, and the solvent was a 1:1 volume ratio mixture of EC and DEC. The counter electrode was a lithium metal sheet, and the separator was a polypropylene (PP) membrane. All coin cells were assembled in an argon-filled glove box.

[0102] Then, the following performance tests were performed on each button cell: Electrochemical performance was performed on a Wuhan Landian CT2001A battery tester. The charge / discharge voltage range was 0.005V to 1.5V, and the charge / discharge rate was 0.1C. The discharge specific capacity and initial efficiency of the corresponding coin cell were tested. At the same time, the cycle performance (0.1C / 0.1C, 100 cycles) of the corresponding coin cell was also tested.

[0103] Full charge expansion test: The thickness of the electrode after rolling is D1. When fully charged to 100% SOC, the thickness of the electrode is D2. Full charge expansion = (D2-D1) / D1.

[0104] The lithium-ion diffusion coefficient of the material was tested using GITT. The test results are shown in Table 2.

[0105] Table 1

[0106] As shown in Table 1, the average pore size of Examples 1-10 ranges from 2.05 to 2.48 nm, and the effective pore volume ranges from 1.00 to 1.15 cm³. 3 / g, the pore volume ratio of >5nm ranges from 4.25% to 6.10%, and the specific surface area ranges from 1835 to 2000m². 2 / g. The above data shows that the present invention successfully constructed a mesoporous porous carbon material with well-developed channels and a stable structure through the synergistic combination of stepwise activation, hierarchical pore formation, phosphorus-based flame retardant modification and organometallic loading. In Examples 1, 2, 4, and 6, phosphorus-based flame retardants were introduced to suppress excessive ablation of the carbon skeleton during heat treatment, achieving in-situ phosphorus doping and effectively optimizing the carbon skeleton structure, stabilizing pores, and increasing pore volume and mesopore ratio. Examples 4, 7, and 8 further added amine crosslinking agents to enhance the crosslinking degree of the precursor and strengthen the stability of the carbon skeleton. Examples 5 and 8 added densification treatment to improve the uniformity of component dispersion and optimize particle packing. Example 3 used steam activation at 1400℃ and secondary oxygen activation, which improved the lithium-ion diffusion coefficient while obtaining a larger average pore size and a higher mesopore ratio, verifying the extreme controllability of this method in constructing fast ion transport channels, while resulting in a slightly higher powder resistivity than conventional processes. Examples 9 and 10 aimed to shorten the total activation time and pursue the ultimate effective pore volume, respectively, verifying the wide adaptability of this preparation method in high-efficiency production and high-capacity scenarios, further demonstrating the advantage of the comprehensive performance that the technical solution of this invention can be customized as needed, but at the same time, it increased the carbon skeleton defects and the resistivity increased to 99.8 and 92.4 Ω·cm.

[0107] The tap density range of Examples 1-10 is 0.40-0.46 g / cm³. 3 The crushing strength ranged from 195 to 234 MPa. Higher tap density and crushing strength reflect regular particle morphology, tight packing, and high skeletal strength. Comparative Example 1, without the addition of phosphorus-based flame retardant, showed lower tap density and crushing strength, indicating that the lack of phosphorus-based flame retardant leads to a loose carbon skeleton and decreased structural stability. Comparative Example 3, without the introduction of organometallic polymers, and Comparative Example 4, omitting the secondary activation step, both exhibited loose particle packing and insufficient structural strength. Comparative Example 2, without the addition of a pore-forming agent, showed a significant reduction in pore volume and mesopore ratio. Comparative Example 5, without molding treatment, showed uneven particle dispersion and a decreased tap density.

[0108] In summary, the data in Table 1 fully demonstrate that the synergistic combination of stepwise activation, graded pore formation, organometallic loading, phosphorus-based flame retardant modification, amine crosslinking, and densification treatment as defined in this invention enables the material to possess high pore volume, high mesopore ratio, low resistivity, high tap density, and high crushing strength. The absence of any component or process will lead to the deterioration of the material's physical and chemical properties.

[0109] Table 2

[0110] As shown in Table 2, the discharge specific capacity of Examples 1–10 ranges from 290.4 to 323.5 mAh / g, the initial efficiency ranges from 41.4% to 47.8%, the cycle performance ranges from 85.0% to 88.9%, the full-charge expansion ranges from 4.78% to 8.20%, and the lithium-ion diffusion coefficient ranges from 1.05 × 10⁻⁶. -5 ~6.78×10 -5 cm 2 / s. The above data shows that the present invention improves the lithium-ion transport capacity and structural stability of the material through the synergistic combination of pore structure regulation, phosphorus-based flame retardant modification, metal component loading, and interface modification. Among them, Examples 1, 2, 4, and 6 introduce phosphorus-based flame retardants to achieve in-situ phosphorus doping, optimize the carbon matrix interface, reduce interface impedance, and improve ion conduction efficiency, enabling the material to obtain higher discharge specific capacity and first-cycle efficiency; Examples 4, 7, and 8 further add amine-based crosslinking agents to enhance the crosslinking degree and structural stability of the carbon skeleton, effectively suppress volume deformation during lithium insertion and extraction, and improve cycle stability; Examples 5 and 8 also add densification treatment to promote uniform penetration of organometallic components into the pores, optimize the particle packing structure, further reduce full-charge expansion, and improve cycle retention. Example 3, due to the high-intensity activation using 1400℃ water vapor and oxygen, achieved the highest lithium-ion diffusion coefficient and optimal cycle performance, but the increased carbon skeleton defects led to a lower initial efficiency. Example 9, due to the significantly shortened activation time, improved production efficiency while experiencing slightly higher full-charge expansion. Example 10, in order to achieve high specific capacity by limiting pore volume, sacrificed initial efficiency slightly, but the overall electrochemical performance remained excellent, fully demonstrating the flexibility of this invention to adjust the overall performance as needed.

[0111] The cycle performance of Examples 1-10 ranged from 85.0% to 88.9%, which is generally at a high level. Among them, Example 9, which used a shorter activation time, still maintained stable cycle performance. This shows that the present invention, by optimizing the pore structure, uniformly loading active sites, and strengthening the carbon skeleton, can effectively buffer the volume deformation of the material and improve the battery cycle life and structural stability.

[0112] The full-charge expansion range of Examples 1-10 was 4.78%-8.20%, which was generally lower than that of the comparative examples. The lower full-charge expansion rate reflects that the material undergoes less structural deformation and stronger mechanical stability during lithium insertion / extraction. Comparative Example 1, which did not add phosphorus-based flame retardant, had lower tap density and crush strength, indicating that the lack of phosphorus-based flame retardant would cause a loose carbon skeleton and a decrease in structural stability. Comparative Example 3, which did not introduce organometallic polymers, and Comparative Example 4, which omitted the secondary activation step, both showed problems of loose particle packing and insufficient structural strength. Comparative Example 2, which did not add pore-forming agent, had hindered ion transport, resulting in a decrease in specific capacity and cycle performance. Comparative Example 5, which did not undergo molding treatment, had uneven particle dispersion, resulting in a significant decrease in initial efficiency and cycle retention.

[0113] In summary, the data in Table 2 fully demonstrate that the synergistic combination of stepwise activation, graded pore formation, organometallic loading, phosphorus-based flame retardant modification, amine crosslinking, and densification treatment as defined in this invention enables the material to possess high specific capacity, high initial efficiency, excellent cycle stability, and low expansion characteristics. The absence of any component or process will lead to the deterioration of the battery's electrochemical performance.

[0114] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a mesoporous porous carbon composite material, characterized in that, Includes the following steps: S1. The carbon source, pore-forming agent and phosphorus-based flame retardant are mixed and then molded to obtain the first intermediate. S2. The first intermediate is subjected to a first heat treatment in the atmosphere of the first activating gas to obtain the precursor material; S3. Mix the precursor material and the organometallic polymer, and dry them to obtain the second intermediate; S4. The second intermediate is subjected to a second heat treatment in the atmosphere of the second activating gas to obtain the mesoporous porous carbon composite material.

2. The method for preparing a mesoporous porous carbon composite material according to claim 1, characterized in that, The carbon source includes glycosyl compounds; The glycosyl compound includes at least one of glucose, sucrose, fructose, maltose, or starch.

3. The preparation method according to claim 1, characterized in that, The pore-forming agent includes at least one of zinc acetate, zinc ethylhexanoate, zinc laurate, zinc oxalate, zinc basic stearate, zinc citrate, or zinc formate.

4. The preparation method according to claim 1, characterized in that, The chemical activity of the first activating gas is higher than that of the second activating gas; The first activating gas includes water vapor and / or carbon dioxide; The second activating gas includes at least one of fluorine, chlorine, hydrogen, or oxygen.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the precursor material to the organometallic polymer is 100:10 to 30.

6. The preparation method according to claim 1 or claim 5, characterized in that, The organometallic polymer includes at least one of pentamethylcyclopentaenoic nickel, pentacarbonyl iron, dimethylplatinum dichloride, triphenylchromium, or ferrocene.

7. The preparation method according to claim 1, characterized in that, The phosphorus-based flame retardant includes at least one of phosphorus-based triaryl phosphate, trialkyl phosphate, resorcinol bis(diphenyl phosphate), tri(trimethylsilyl) phosphate, or tripolyphosphate. The mass ratio of the carbon source, phosphorus-based flame retardant, and pore-forming agent is 100:5-20:10-30.

8. The preparation method according to claim 2, characterized in that, An amine crosslinking agent is also added when mixing the carbon source, pore-forming agent and phosphorus-based flame retardant. The amine crosslinking agent includes at least one of diethylenetriamine, polyethylenepolyamine, ethylenediamine, hexamethylenediamine, butylenediamine, or diethylenetriamine; The mass ratio of the glycosyl compound, pore-forming agent, and amine crosslinking agent is 100:10-30:5-10.

9. The preparation method according to claim 1, characterized in that, The temperature of the first heat treatment is 1000–1400℃; The flow rate of the first activating gas is 100–500 ml / min; The first activating gas is introduced for 30 to 300 minutes; The temperature of the second heat treatment is 900–1100°C; The flow rate of the second activating gas is 100–500 ml / min; The second activating gas is introduced for 30 to 300 minutes.

10. The preparation method according to claim 1, characterized in that, Before drying, the precursor material is further densified to allow the organometallic polymer to penetrate into the pores and surface depressions of the precursor material. The densification process includes at least one of vacuum extrusion, vacuum impregnation, or centrifugal impregnation.

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