A power type porous carbon composite material, a preparation method thereof, a silicon-carbon negative electrode material and a lithium ion battery

Abstract

The application provides a power type porous carbon composite material and a preparation method thereof, a silicon-carbon negative electrode material and a lithium ion battery, and belongs to the technical field of battery materials. The preparation method comprises the following steps: mixing a resin and a pore-forming agent, performing carbonization treatment, and obtaining a resin-based porous carbon; mixing the resin-based porous carbon, petroleum coke-based porous carbon and an organic catalyst to obtain a mixed precursor, then depositing carbon nanotubes in the pores of the mixed precursor, and performing activation treatment to obtain the power type porous carbon composite material. The application adopts the composite design of the resin-based porous carbon and the petroleum coke-based porous carbon, improves the power performance of the material, reduces the volume expansion, and improves the compaction density; the doping of the organic catalyst and the deposition of the carbon nanotubes are beneficial to reducing the material impedance, improving the electronic conductivity, and the carbon nanotubes can bridge the resin-based porous carbon and the petroleum coke-based porous carbon, can reduce the interface contact resistance, shorten the ion diffusion path, and improve the specific capacity and the cycle life of the material.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to a power-type porous carbon composite material and its preparation method, silicon-carbon anode materials, and lithium-ion batteries. Background Technology

[0002] Porous carbon materials are key electrode materials for high-performance capacitors and energy storage devices, and their power performance is closely related to their pore structure, conductivity, and material expansion behavior. Currently, commercially available porous carbon materials are mainly prepared by carbonizing resin-based precursors and then activating them with a single activator (such as carbon dioxide, steam, or potassium hydroxide). Materials obtained through this process generally suffer from uneven pore structure distribution and low graphitization, resulting in high powder resistivity and reduced rate performance, thus limiting their application in high-power applications.

[0003] To improve the electrochemical performance of porous carbon materials, studies have attempted to suppress material expansion and enhance conductivity through heteroatom doping and pore structure regulation. For example, patent CN118419892A discloses a metal-doped porous carbon, a silicon-carbon material, and its preparation method. The method involves dispersing a carbon-based precursor, a pore-forming agent, and lithium amino groups in an organic solvent, followed by drying and curing to obtain a porous carbon precursor; then, by introducing an alkaline gas and treating at high temperature, lithium-doped porous carbon is obtained. While this process reduces impedance, the unreasonable distribution of the material's pore structure causes localized expansion. Furthermore, the lack of graphitization peaks in the porous carbon results in higher impedance, reducing its power performance.

[0004] Therefore, how to synergistically suppress the volume expansion and reduce the impedance of porous carbon materials while improving their electronic conductivity and power performance is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a power-type porous carbon composite material and its preparation method, a silicon-carbon anode material, and a lithium-ion battery. This invention employs a composite design of resin-based porous carbon and petroleum coke-based porous carbon, fully leveraging their synergistic effects in structure and performance. It not only fully utilizes the high compressive strength and low expansion of resin-based porous carbon, but also fully demonstrates the good anisotropy and low orientation of petroleum coke-based porous carbon. This complementary and synergistic approach significantly improves the power performance of the porous carbon composite material, effectively reduces volume expansion during charge and discharge, and increases compaction density. The doping of an organic catalyst catalyzes carbon nanotube deposition, reducing impedance and enhancing the material's compressive strength. The introduction of carbon nanotubes not only bridges the resin-based and petroleum coke-based porous carbon, constructing a three-dimensional, highly efficient conductive network that runs throughout the entire structure, thus reducing interfacial contact resistance, but also, by penetrating the pores of both materials, greatly shortens the ion diffusion path, facilitating the storage of active substances. This allows for further improvement in the material's specific capacity while maintaining high power output. Furthermore, the high mechanical strength of the carbon nanotubes enhances the stability of the material structure and improves its cycle life.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a power-type porous carbon composite material, the method comprising the following steps:

[0008] The resin and pore-forming agent are mixed and carbonized to obtain resin-based porous carbon.

[0009] The resin-based porous carbon, petroleum coke-based porous carbon, and organic catalyst are mixed to obtain a mixed precursor. Then, carbon nanotubes are deposited in the pores of the mixed precursor, followed by activation treatment to obtain the power-type porous carbon composite material.

[0010] This invention employs a composite design of resin-based porous carbon and petroleum coke-based porous carbon, fully leveraging their synergistic effects in structure and performance. It not only fully utilizes the high compressive strength and low expansion of resin-based porous carbon, but also fully demonstrates the good anisotropy and low orientation of petroleum coke-based porous carbon. This complementary and synergistic approach significantly improves the power performance of the porous carbon composite material, effectively reduces volume expansion during charge and discharge, and increases compaction density. The doping of an organic catalyst catalyzes carbon nanotube deposition, reducing impedance and enhancing the material's compressive strength. The introduction of carbon nanotubes not only bridges the resin-based and petroleum coke-based porous carbon, constructing a three-dimensional, highly efficient conductive network that runs throughout the entire structure, thus reducing interfacial contact resistance, but also, by penetrating the pores of both materials, greatly shortens the ion diffusion path, facilitating the storage of active substances. This allows for further improvement in the material's specific capacity while maintaining high power output. Furthermore, the high mechanical strength of the carbon nanotubes enhances the stability of the material structure and improves its cycle life.

[0011] The purpose of the activation treatment in this invention is to regulate the pore structure of the material, thereby effectively improving the specific capacity of the material; reducing the interfacial contact resistance between carbon nanotubes and the deposited object, and improving the electronic conductivity of the material.

[0012] Preferably, the resin is a thermosetting resin.

[0013] Preferably, the thermosetting resin includes any one or a combination of at least two of phenolic resin, urea-formaldehyde resin, epoxy resin, polyurethane, or polyimide.

[0014] Preferably, the pore-forming agent includes an organic pore-forming agent and an inorganic pore-forming agent, wherein the mass ratio of the organic pore-forming agent to the inorganic pore-forming agent is (10-30):(10-30);

[0015] The range of organic pore-forming agent selection is "10-30", for example, it can be 10, 15, 20, 25 or 30, etc.

[0016] The selection range for inorganic pore-forming agents is "10-30", for example, it can be 10, 15, 20, 25 or 30, etc.

[0017] This invention, by adjusting the mass ratio of organic and inorganic pore-forming agents, synergistically constructs a multi-level pore structure composed of nanopores (small pores) formed by organic pore-forming agents and macropores formed by inorganic pore-forming agents. This achieves a gradient distribution and rational combination of pore structures, which not only effectively buffers the stress of the carbon skeleton during charging and discharging and inhibits material expansion, but also provides abundant storage and transportation space for active substances, thereby significantly improving the loading and utilization efficiency of active substances.

[0018] Preferably, the organic pore-forming agent includes any one of polystyrene, polyethylene, polypropylene, polyvinyl chloride, or polymethyl methacrylate.

[0019] Preferably, the inorganic pore-forming agent includes any one or a combination of at least two of ammonium sulfate, ammonium carbonate, ammonium bicarbonate, magnesium carbonate, or lithium carbonate.

[0020] Preferably, the mass ratio of the resin to the pore-forming agent is 100:(20-60), for example, it can be 100:20, 100:25, 100:30, 100:35, 100:40, 100:45, 100:50, 100:55 or 100:60, etc.

[0021] In this invention, the above-mentioned mass ratio not only provides sufficient specific surface area to increase active sites, but also ensures the structural strength of the carbon skeleton, effectively suppresses the expansion of the material during charging and discharging, and lays a good foundation for the uniform deposition of carbon nanotubes.

[0022] Preferably, the carbonization process includes a primary carbonization and a secondary carbonization performed by sequentially increasing the temperature.

[0023] This invention employs multi-stage heating carbonization. The first stage of carbonization initially constructs a stable carbon framework, while the second stage of carbonization optimizes the structure at higher temperatures, achieving precise control over the pore structure and laying the structural foundation for subsequent processes. More importantly, the organic pore-forming agent decomposes to form micropores during the first stage of carbonization, while the inorganic pore-forming agent functions during the second stage. This allows the organic and inorganic pore-forming agents to work together during both stages of carbonization to provide more abundant storage and transport space for the active material, further enhancing the loading capacity and utilization efficiency of the active material.

[0024] Preferably, the temperature of the primary carbonization is 500-800℃, for example, 500℃, 600℃, 700℃ or 800℃, and the holding time is 1-3h, for example, 1h, 1.5h, 2h, 2.5h or 3h.

[0025] Preferably, the temperature of the secondary carbonization is 850-1200℃, for example, 850℃, 900℃, 1000℃, 1100℃ or 1200℃, and the holding time is 1-3h, for example, 1h, 1.5h, 2h, 2.5h or 3h.

[0026] Preferably, carbon dioxide gas is introduced during the secondary carbonization process.

[0027] This invention introduces carbon dioxide gas during the high-temperature secondary carbonization process. The purpose is to utilize the synergistic effect between carbon dioxide and the pore-forming agent to open up large and small pores, reduce material impedance, and increase the density of the carbon skeleton, thereby improving the compressive strength of the material. This achieves precise control over the pore structure and surface chemical properties of resin-based porous carbon, which is beneficial for increasing the effective specific surface area and enhancing electrochemical activity.

[0028] Preferably, the porosity of the petroleum coke-based porous carbon is 30-50%, for example, it can be 30%, 35%, 40%, 45% or 50%; the volatile matter is 10-15%, for example, it can be 10%, 11%, 12%, 13%, 14% or 15%.

[0029] It should be noted that the present invention does not limit the preparation method of petroleum coke-based porous carbon. For example, petroleum coke can be mixed with an activator (such as potassium hydroxide) for activation, followed by acid washing, water washing, and drying. The above preparation methods are all known in the art and can be selected according to the required pore structure and performance requirements.

[0030] Preferably, the organic catalyst is an organometallic catalyst.

[0031] It should be noted that organometallic catalysts can leverage the existing porous carbon framework structure, through the catalytic action of metals and the regulatory function of organic ligands, to achieve "precise structural optimization" and "targeted functional endowment," addressing the shortcomings of native porous carbon in terms of conductivity, selectivity, and activity. The core lies in targeting and resolving the performance defects of native porous carbon. On the one hand, this involves optimizing the pore structure, opening up closed pores and ultrapores, and improving pore utilization; on the other hand, acting as a surface modifier to regulate the type and ratio of functional groups, improving the compatibility and selectivity of activation intermediates; and simultaneously introducing metal active sites to achieve specific application functions such as catalysis and electrochemistry.

[0032] Preferably, the organometallic catalyst comprises any one or a combination of at least two of ferrocene, titanium dichlorocerocene, or zirconium dichlorocerocene.

[0033] Preferably, the mass ratio of the resin-based porous carbon, the petroleum coke-based porous carbon, and the organic catalyst is 100:(50-200):(5-20), wherein the petroleum coke-based porous carbon is selected in the range of "50-200", for example, 50, 100, 150, or 200, and the organic catalyst is selected in the range of "5-20", for example, 5, 10, 15, or 20.

[0034] In this invention, by using resin-based porous carbon, petroleum coke-based porous carbon, and organic catalyst in a specific mass ratio in synergistic combination, on the one hand, the organic catalyst can be used to catalyze the deposition of carbon nanotubes, reduce impedance, and improve the compressive strength of the material; on the other hand, the organic catalyst can play a precise regulatory role on the functional groups on the surface of the material, and at the same time, the pore reconstruction increases the effective specific surface area and improves the mass transfer efficiency, thereby optimizing the kinetic properties of the material and achieving the purpose of preparing high-power porous carbon materials.

[0035] Preferably, the carbon nanotube deposition method includes vapor phase deposition.

[0036] The parameters in the vapor deposition method include:

[0037] The flow rate of the carbon source gas is 10-100 mL / min, for example, 10 mL / min, 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min or 100 mL / min, etc.; the deposition time is 30-300 min, for example, 30 min, 60 min, 100 min, 150 min, 200 min, 250 min or 300 min, etc.; and the deposition temperature is 700-1000℃, for example, 700℃, 800℃, 900℃ or 1000℃, etc.

[0038] Preferably, the carbon source gas includes any one or a combination of at least two of methane, ethylene, acetylene, or propyne.

[0039] Preferably, water vapor is introduced during the activation process.

[0040] Preferably, the activation temperature is 900-1100℃, for example, it can be 900℃, 950℃, 1000℃, 1050℃ or 1100℃.

[0041] Preferably, the activation time is 60-300 min, for example, it can be 60 min, 100 min, 150 min, 200 min, 250 min or 300 min.

[0042] Preferably, the preparation method includes the following steps:

[0043] (1) Mix thermosetting resin, organic pore-forming agent and inorganic pore-forming agent, and then perform primary carbonization at 500-800℃ for 1-3h. Then, raise the temperature to 850-1200℃ and pass carbon dioxide gas through at a flow rate of 100-500mL / min (e.g., 100mL / min, 110mL / min, 120mL / min, 130mL / min, 140mL / min or 150mL / min, etc.) for 1-3h to obtain resin-based porous carbon.

[0044] The mass ratio of the thermosetting resin, organic pore-forming agent, and inorganic pore-forming agent is 100:(10-30):(10-30); the thermosetting resin includes any one or a combination of at least two of phenolic resin, urea-formaldehyde resin, epoxy resin, polyurethane, or polyimide; the organic pore-forming agent includes any one of polystyrene, polyethylene, polypropylene, polyvinyl chloride, or polymethyl methacrylate; and the inorganic pore-forming agent includes any one or a combination of at least two of ammonium sulfate, ammonium carbonate, ammonium bicarbonate, magnesium carbonate, or lithium carbonate.

[0045] (2) The resin-based porous carbon and petroleum coke-based porous carbon are added to an organometallic catalyst solution with a mass concentration of 1-10 wt% (for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, etc.), mixed evenly, and then dried to obtain a mixed precursor.

[0046] The petroleum coke-based porous carbon has a porosity of 30-50% and a volatile content of 10-15%; the mass ratio of the solute in the resin-based porous carbon, the petroleum coke-based porous carbon, and the organometallic catalyst solution is 100:(50-200):(5-20); the solute includes any one or a combination of at least two of ferrocene, titanium diacene chloride, or zirconium diacene chloride.

[0047] (3) Carbon nanotubes are formed in situ in the pores of the mixed precursor by vapor deposition. Then, water vapor is introduced at a flow rate of 50-200 mL / min (e.g., 50 mL / min, 100 mL / min, 150 mL / min or 200 mL / min) for activation treatment to obtain a power-type porous carbon composite material.

[0048] The parameters in the vapor deposition method include: a carbon source gas flow rate of 10-100 mL / min, a deposition time of 30-300 min, and a deposition temperature of 700-1000℃; the carbon source gas includes any one or a combination of at least two of methane, ethylene, acetylene, or propyne; the activation temperature is 900-1100℃; and the activation time is 60-300 min.

[0049] In a first aspect, the present invention provides a power-type porous carbon composite material, which is prepared by the preparation method described in the first aspect.

[0050] In a first aspect, the present invention provides a silicon-carbon anode material, which is prepared by combining the power-type porous carbon composite material described in the second aspect with silicon material.

[0051] In a first aspect, the present invention provides a lithium-ion battery, wherein the negative electrode of the lithium-ion battery comprises the silicon-carbon negative electrode material as described in the third aspect.

[0052] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] This invention employs a composite design of resin-based porous carbon and petroleum coke-based porous carbon, fully leveraging their synergistic effects in structure and performance. It not only fully utilizes the high compressive strength and low expansion of resin-based porous carbon, but also fully demonstrates the good anisotropy and low orientation of petroleum coke-based porous carbon. This complementary and synergistic approach significantly improves the power performance of the porous carbon composite material, effectively reduces volume expansion during charge and discharge, and increases compaction density. The doping of an organic catalyst catalyzes carbon nanotube deposition, reducing impedance and enhancing the material's compressive strength. The introduction of carbon nanotubes not only bridges the resin-based and petroleum coke-based porous carbon, constructing a three-dimensional, highly efficient conductive network that runs throughout the entire structure, thus reducing interfacial contact resistance, but also, by penetrating the pores of both materials, greatly shortens the ion diffusion path, facilitating the storage of active substances. This allows for further improvement in the material's specific capacity while maintaining high power output. Furthermore, the high mechanical strength of the carbon nanotubes enhances the stability of the material structure and improves its cycle life. Attached Figure Description

[0055] Figure 1 This is a SEM image of the power-type porous carbon composite material prepared in Example 1 of this invention at a magnification of 10,000. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] Example 1

[0058] This embodiment provides a method for preparing a power-type porous carbon composite material, the method comprising the following steps:

[0059] (1) Mix 100g of thermosetting resin, 20g of organic pore-forming agent and 20g of inorganic pore-forming agent, and then perform primary carbonization at 650℃ for 2h. Then, raise the temperature to 950℃ and pass carbon dioxide gas at a flow rate of 300mL / min for 2h of secondary carbonization to obtain resin-based porous carbon.

[0060] The mass ratio of the thermosetting resin, the organic pore-forming agent, and the inorganic pore-forming agent is 100:20:20; the thermosetting resin is phenolic resin, the organic pore-forming agent is polystyrene, and the inorganic pore-forming agent is ammonium sulfate.

[0061] (2) Add 100g of the resin-based porous carbon and 100g of petroleum coke-based porous carbon to 200g of an aqueous solution of an organometallic catalyst with a mass concentration of 5wt%, mix evenly, and then spray dry to obtain a mixed precursor.

[0062] The petroleum coke-based porous carbon has a porosity of 40% and a volatile content of 12%; the mass ratio of the solute in the resin-based porous carbon, the petroleum coke-based porous carbon, and the organometallic catalyst aqueous solution is 100:100:10; and the solute is ferrocene.

[0063] (3) The mixed precursor is transferred to a tube furnace and carbon nanotubes are formed in situ in the pores of the mixed precursor by vapor deposition. Then, water vapor is introduced at a flow rate of 100 mL / min for activation treatment to obtain a power-type porous carbon composite material.

[0064] The parameters in the vapor deposition method include: ethylene gas flow rate of 50 mL / min, deposition time of 150 min, and deposition temperature of 800 °C; the activation temperature is 1000 °C; and the activation time is 150 min.

[0065] Figure 1 The SEM image of the power-type porous carbon composite material prepared in this embodiment is shown at 10,000 magnification. As can be seen from the figure, the material exhibits a spherical structure with uniform size distribution and a particle size between 5 and 10 μm.

[0066] Example 2

[0067] This embodiment provides a method for preparing a power-type porous carbon composite material, the method comprising the following steps:

[0068] (1) Mix 100g of thermosetting resin, 10g of organic pore-forming agent and 10g of inorganic pore-forming agent, and then perform primary carbonization at 500℃ for 3h. Then, raise the temperature to 850℃ and pass carbon dioxide gas at a flow rate of 100mL / min for secondary carbonization for 3h to obtain resin-based porous carbon.

[0069] The mass ratio of the thermosetting resin, the organic pore-forming agent, and the inorganic pore-forming agent is 100:10:10; the thermosetting resin is urea-formaldehyde resin, the organic pore-forming agent is polyethylene, and the inorganic pore-forming agent is ammonium carbonate.

[0070] (2) Add 100g of the resin-based porous carbon and 50g of petroleum coke-based porous carbon to 500g of an aqueous solution of an organometallic catalyst with a mass concentration of 1wt%, mix evenly, and then spray dry to obtain a mixed precursor.

[0071] The petroleum coke-based porous carbon has a porosity of 30% and a volatile content of 10%; the mass ratio of the solute in the resin-based porous carbon, the petroleum coke-based porous carbon, and the organometallic catalyst aqueous solution is 100:50:5; and the solute is titanium dichlorophenoxyacetate.

[0072] (3) The mixed precursor is transferred to a tube furnace and carbon nanotubes are formed in situ in the pores of the mixed precursor by vapor deposition. Then, water vapor is introduced at a flow rate of 50 mL / min for activation treatment to obtain a power-type porous carbon composite material.

[0073] The parameters in the vapor deposition method include: acetylene gas flow rate of 10 mL / min, deposition time of 300 min, and deposition temperature of 700 °C; the activation temperature is 900 °C; and the activation time is 300 min.

[0074] Example 3

[0075] This embodiment provides a method for preparing a power-type porous carbon composite material, the method comprising the following steps:

[0076] (1) Mix 100g of thermosetting resin, 30g of organic pore-forming agent and 30g of inorganic pore-forming agent, and then perform primary carbonization at 800℃ for 1h. Then, raise the temperature to 1200℃ and pass carbon dioxide gas at a flow rate of 500mL / min for 1h of secondary carbonization to obtain resin-based porous carbon.

[0077] The mass ratio of the thermosetting resin, the organic pore-forming agent, and the inorganic pore-forming agent is 100:30:30; the thermosetting resin is epoxy resin, the organic pore-forming agent is polypropylene, and the inorganic pore-forming agent is ammonium bicarbonate.

[0078] (2) Add 100g of the resin-based porous carbon and 200g of petroleum coke-based porous carbon to 200g of an aqueous solution of an organometallic catalyst with a mass concentration of 10wt%, mix evenly, and then spray dry to obtain a mixed precursor.

[0079] The petroleum coke-based porous carbon has a porosity of 50% and a volatile content of 15%; the mass ratio of the solute in the resin-based porous carbon, the petroleum coke-based porous carbon, and the organometallic catalyst aqueous solution is 100:200:20; and the solute is zirconium dichloroethylene.

[0080] (3) The mixed precursor is transferred to a tube furnace and carbon nanotubes are formed in situ in the pores of the mixed precursor by vapor deposition. Then, water vapor is introduced at a flow rate of 200 mL / min for activation treatment to obtain a power-type porous carbon composite material.

[0081] The parameters in the vapor deposition method include: a methane gas flow rate of 100 mL / min, a deposition time of 30 min, and a deposition temperature of 1000 °C; the activation temperature is 1100 °C; and the activation time is 60 min.

[0082] Example 4

[0083] The difference between this embodiment and embodiment 1 is that no organic pore-forming agent is added in step (1).

[0084] The remaining preparation methods and parameters are consistent with those in Example 1.

[0085] Example 5

[0086] The difference between this embodiment and embodiment 1 is that no inorganic pore-forming agent is added in step (1).

[0087] The remaining preparation methods and parameters are consistent with those in Example 1.

[0088] Example 6

[0089] The difference between this embodiment and Embodiment 1 is that primary carbonization is not performed in step (1).

[0090] The remaining preparation methods and parameters are consistent with those in Example 1.

[0091] Example 7

[0092] The difference between this embodiment and embodiment 1 is that carbon dioxide gas is not introduced during the secondary carbonization process in step (1).

[0093] The remaining preparation methods and parameters are consistent with those in Example 1.

[0094] Example 8

[0095] The difference between this embodiment and Embodiment 1 is that the mass ratio of the resin-based porous carbon to the petroleum coke-based porous carbon is 100:250.

[0096] The remaining preparation methods and parameters are consistent with those in Example 1.

[0097] Example 9

[0098] The difference between this embodiment and Embodiment 1 is that the mass ratio of the resin-based porous carbon to the petroleum coke-based porous carbon is 100:40.

[0099] The remaining preparation methods and parameters are consistent with those in Example 1.

[0100] Example 10

[0101] The difference between this embodiment and Embodiment 1 is that the mass ratio of the solute in the resin-based porous carbon, the petroleum coke-based porous carbon, and the organometallic catalyst aqueous solution is 100:100:50.

[0102] The remaining preparation methods and parameters are consistent with those in Example 1.

[0103] Comparative Example 1

[0104] The difference between this comparative example and Example 1 is that petroleum coke-based porous carbon is not added in step (2).

[0105] The remaining preparation methods and parameters are consistent with those in Example 1.

[0106] Comparative Example 2

[0107] The difference between this comparative example and Example 1 is that no aqueous solution of organometallic catalyst is added in step (2).

[0108] The remaining preparation methods and parameters are consistent with those in Example 1.

[0109] Comparative Example 3

[0110] The difference between this comparative example and Example 1 is that carbon nanotubes are not deposited in step (3).

[0111] The remaining preparation methods and parameters are consistent with those in Example 1.

[0112] Comparative Example 4

[0113] The difference between this comparative example and Example 1 is that no activation treatment is performed in step (3).

[0114] The remaining preparation methods and parameters are consistent with those in Example 1.

[0115] Performance testing

[0116] I. The pore volume and pore size of the power-type porous carbon composite materials prepared in the above examples and comparative examples were tested according to the national standard GB / T-38949-2020 "Determination of Pore Size of Porous Membranes - Standard Particle Method"; the particle size, powder compaction density (2T), specific surface area and tap density of the materials were tested according to the national standard GB / T38823-2020 "Silicon-Carbon Anode Materials"; the powder conductivity of the materials was tested using a four-probe tester; and the diffusion coefficient of the materials was tested using GITT.

[0117] The test results are shown in Table 1.

[0118] Table 1

[0119]

[0120] II. The compressive strength of materials is tested using the pressure-specific surface area method, which involves applying a certain pressure to cause a change in the specific surface area of ​​the material, thereby determining the material's compressive strength.

[0121] The test results are shown in Table 2.

[0122] Table 2

[0123]

[0124] III. Using the power-type porous carbon composite material prepared in the above embodiments and comparative examples as the negative electrode material for lithium-ion batteries, a coin cell is fabricated. The specific steps include: adding a binder, a conductive agent, and a solvent to the power-type porous carbon composite material, stirring to form a slurry, coating it onto copper foil, and then drying and pressing it to obtain a negative electrode sheet. The binder is LA132, the conductive agent is SP (conductive carbon black), and the solvent is NMP. The ratio of power-type porous carbon composite material:SP:LA132:NMP is 80g:15g:15g:300mL. The electrolyte is a LiPF6 solution with a concentration of 1mol / L, wherein the solvent is a mixture of EC and DEC with a volume ratio of 1:1. A lithium metal sheet is used as the counter electrode, and a polypropylene (PP) membrane is used as the separator. The coin cell is assembled in a glove box under an argon atmosphere.

[0125] Electrochemical performance tests of coin cells were conducted using a Wuhan Landian CT2001A battery tester: the discharge voltage range was 0.005V to 2.0V, the charge / discharge rate was 0.1C, the discharge specific capacity and initial efficiency of the corresponding coin cells were tested, and the room temperature charge DCR (50% SOC) and cycle performance (0.1C / 0.1C, 100 cycles) of the corresponding coin cells were also tested.

[0126] The test results are shown in Table 3.

[0127] Table 3

[0128]

[0129] analyze:

[0130] As shown in Tables 1 and 3, the power-type porous carbon composite materials prepared in Examples 1-3 have low powder resistivity and high initial efficiency. This is because the metal in the power-type porous carbon composite material improves the electronic conductivity of the material, and the addition of pore-forming agents to the resin improves the pore volume and pore size of the material, increases the specific surface area, improves the liquid absorption capacity of the material, and improves the diffusion coefficient of the material.

[0131] As shown in Table 2, after being subjected to stepped pressure, the increase in specific surface area of ​​the power-type porous carbon composite materials prepared in Examples 1-3 was relatively small, indicating that the material has strong compressive strength under high pressure. This is because the material has a reasonable distribution of pore structure, which can effectively improve the compressive strength of the material, and the doping of carbon nanotubes can also improve the compressive strength of the material.

[0132] A comparison of Example 1 and Examples 4-5 shows that without the addition of a pore-forming agent, the pore-forming effect is significantly weakened. The specific surface area and pore volume of Examples 4-5 are significantly lower than those of Example 1, the powder resistivity is increased, the expected activation effect cannot be achieved, and the capacity is low.

[0133] As can be seen from the comparison between Example 1 and Example 6, if primary carbonization is not performed in step (1), although the activation effect is not significantly different, the precursor fails to form a stable carbon skeleton before activation, resulting in low compaction density and tap density, which in turn affects the mechanical strength, coating stability and other physical properties of the final product.

[0134] A comparison between Example 1 and Example 7 shows that if carbon dioxide gas is not introduced during the secondary carbonization process, the entire process route lacks a secondary physical activation stage, the activation effect is significantly weakened, the specific surface area and pore volume are significantly reduced compared to Example 1, and the capacity decreases significantly.

[0135] As can be seen from the comparison between Example 1 and Examples 8-9, if the mass ratio of resin-based porous carbon to petroleum coke-based porous carbon is too small, it will affect the pore-forming effect during the activation process and will not be conducive to the improvement of capacity; if the mass ratio of resin-based porous carbon to petroleum coke-based porous carbon is too large, it will affect the specific surface area after carbonization and the initial coulombic efficiency will be low.

[0136] A comparison of Example 1 and Example 10 shows that if the mass ratio of solute in the aqueous solution of resin-based porous carbon, petroleum coke-based porous carbon and organometallic catalyst is too small, that is, if the amount of organometallic catalyst is too large, although the pore-forming effect is comparable to that of Example 1, the excessive amount of catalyst disrupts the balance of "porous structure-active site-electron / ion transport". Not only is it unable to continuously improve the performance, but it also inhibits the increase in capacity by destroying the porous structure, introducing ineffective components, and hindering mass transfer.

[0137] As can be seen from the comparison between Example 1 and Comparative Example 1, if petroleum coke-based porous carbon is not added, the activation effect becomes worse, the compressive strength of the sample weakens, and the capacity decreases.

[0138] As can be seen from the comparison between Example 1 and Comparative Example 2, if no aqueous solution of organometallic catalyst is added, that is, if no organometallic catalyst is used, the activation effect becomes worse and the capacity decreases significantly.

[0139] As can be seen from the comparison between Example 1 and Comparative Example 3, if carbon nanotubes are not deposited, the effect on the activation result is small, but the capacity decreases due to the reduced number of lithium storage sites.

[0140] As can be seen from the comparison between Example 1 and Comparative Example 4, if no activation treatment is performed, there is no pore-forming process, the specific surface area is far from meeting the requirements of porous carbon, and the capacity is significantly reduced.

[0141] 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 power-type porous carbon composite material, characterized in that, The preparation method includes the following steps: The resin and pore-forming agent are mixed and carbonized to obtain resin-based porous carbon; the pore-forming agent includes an organic pore-forming agent and an inorganic pore-forming agent, and the mass ratio of the organic pore-forming agent to the inorganic pore-forming agent is (10-30):(10-30); the carbonization process includes a primary carbonization and a secondary carbonization carried out by sequentially increasing the temperature; carbon dioxide gas is introduced during the secondary carbonization process. The resin-based porous carbon, petroleum coke-based porous carbon, and organic catalyst are mixed to obtain a mixed precursor. Then, carbon nanotubes are deposited in the pores of the mixed precursor, and then activated to obtain the power-type porous carbon composite material. The mass ratio of the resin-based porous carbon, petroleum coke-based porous carbon, and organic catalyst is 100:(50-200):(5-20).

2. The preparation method according to claim 1, characterized in that, The resin is a thermosetting resin; And / or, the mass ratio of the resin to the pore-forming agent is 100:(20-60).

3. The preparation method according to claim 1, characterized in that, The temperature of the first-stage carbonization is 500-800℃, and the holding time is 1-3 hours; The secondary carbonization temperature is 850-1200℃, and the holding time is 1-3 hours.

4. The preparation method according to claim 1, characterized in that, The porosity of the petroleum coke-based porous carbon is 30-50%, and the volatile matter content is 10-15%. And / or, the organic catalyst is an organometallic catalyst.

5. The preparation method according to claim 1, characterized in that, The carbon nanotube deposition method includes vapor phase deposition; The parameters in the vapor deposition method include: The flow rate of the carbon source gas was 10-100 mL / min, the deposition time was 30-300 min, and the deposition temperature was 700-1000℃.

6. The preparation method according to claim 1, characterized in that, Water vapor is introduced during the activation process; And / or, the activation temperature is 900-1100℃; And / or, the activation time is 60-300 min.

7. The preparation method according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: (1) Mix thermosetting resin, organic pore-forming agent and inorganic pore-forming agent, and then perform primary carbonization at 500-800℃ for 1-3h. Then, raise the temperature to 850-1200℃ and pass carbon dioxide gas at a flow rate of 100-500mL / min for 1-3h secondary carbonization to obtain resin-based porous carbon. The mass ratio of the thermosetting resin, organic pore-forming agent, and inorganic pore-forming agent is 100:(10-30):(10-30); the thermosetting resin includes any one or a combination of at least two of phenolic resin, urea-formaldehyde resin, epoxy resin, polyurethane, or polyimide; the organic pore-forming agent includes any one of polystyrene, polyethylene, polypropylene, polyvinyl chloride, or polymethyl methacrylate; and the inorganic pore-forming agent includes any one or a combination of at least two of ammonium sulfate, ammonium carbonate, ammonium bicarbonate, magnesium carbonate, or lithium carbonate. (2) The resin-based porous carbon and petroleum coke porous carbon are added to an organometallic catalyst solution with a mass concentration of 1-10 wt%, mixed evenly, and then dried to obtain a mixed precursor. The petroleum coke-based porous carbon has a porosity of 30-50% and a volatile content of 10-15%. The mass ratio of the solute in the resin-based porous carbon, the petroleum coke-based porous carbon, and the organometallic catalyst solution is 100:(50-200):(5-20). The solute includes any one or a combination of at least two of ferrocene, titanium diacene chloride, or zirconium diacene chloride. (3) Carbon nanotubes are formed in situ in the pores of the mixed precursor by vapor deposition, and then water vapor is introduced at a flow rate of 50-200 mL / min for activation treatment to obtain a power-type porous carbon composite material. The parameters in the vapor deposition method include: a carbon source gas flow rate of 10-100 mL / min, a deposition time of 30-300 min, and a deposition temperature of 700-1000℃; the carbon source gas includes any one or a combination of at least two of methane, ethylene, acetylene, or propyne; the activation temperature is 900-1100℃; and the activation time is 60-300 min.

8. A power-type porous carbon composite material, characterized in that, The power-type porous carbon composite material is prepared by the preparation method described in any one of claims 1-7.

9. A silicon-carbon anode material, characterized in that, The silicon-carbon anode material is prepared by combining the power-type porous carbon composite material described in claim 8 with silicon material.

10. A lithium-ion battery, characterized in that, The negative electrode of the lithium-ion battery comprises the silicon-carbon negative electrode material as described in claim 9.

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