Novel porous carbon / ordered carbon composite material as well as preparation method and application thereof

Abstract

The invention discloses a novel porous carbon / ordered carbon composite material and a preparation method and application thereof, and the method comprises the following steps: S1, dispersing porous carbon to form a porous carbon dispersion liquid; s2, adjusting the porous carbon dispersion liquid to be acidic, then adding a micromolecule monomer and an initiator into the porous carbon dispersion liquid, promoting in-situ polymerization coating of the micromolecule monomer, and forming a layer of ordered carbon precursor on the surface of the porous carbon; s3, performing solid-liquid separation, calcining the porous carbon of which the surface is coated with the ordered carbon precursor in a protective atmosphere, and carbonizing the ordered carbon precursor into an ordered carbon layer coated on the surface of the porous carbon to obtain a porous carbon / ordered carbon composite material; wherein the micromolecule monomer is selected from one or more of an alkene / alkyne micromolecule monomer, a styrene micromolecule monomer, an acrylate micromolecule monomer, a bifunctional acid / alcohol micromolecule monomer, a cyclic micromolecule monomer, a polymer micromolecule monomer, a biocompatibility micromolecule monomer, a crosslinking micromolecule monomer and a natural source micromolecule monomer.

Description

Technical Field

[0001] This invention relates to the field of lithium battery anode material technology, specifically to a novel porous carbon / ordered carbon composite material and its preparation method and applications. Background Technology

[0002] With the rapid development of new energy vehicles, consumer electronics, and large-scale energy storage systems, the market demand for lithium-ion batteries with high energy density and long cycle life has become increasingly urgent. Currently, commercially available lithium-ion batteries mainly use graphite as the anode material, but graphite has a relatively low theoretical specific capacity (approximately 372 mAh / g), making it difficult to meet the energy density requirements of next-generation batteries. Therefore, developing new high-performance anode materials has become a key focus of industry research.

[0003] Silicon (Si) is considered one of the most promising anode materials due to its ultra-high theoretical specific capacity (~4200 mAh / g, which is far higher than that of traditional graphite anode materials), abundant reserves, and environmental friendliness. However, silicon faces two major problems in practical applications: (1) The first is the volume expansion problem of silicon. Silicon undergoes a volume expansion of about 300% during charging and discharging, which leads to the pulverization of the electrode structure, the shedding of active materials, and a sharp decline in the cycle stability of the battery; (2) The second is the problem of poor conductivity. The poor conductivity of silicon itself will affect the rate performance and charge transport efficiency of the battery. To overcome the shortcomings of silicon materials, many researchers have proposed CVD preparation of silicon-carbon (Si / C) composite anode materials. For example, patents CN113224274A and CN114287072A disclose the preparation of silicon-carbon composite anode materials by embedding silicon nanoparticles into a porous carbon matrix. This combines the advantages of both: ① Utilizing the buffering effect of porous carbon materials, porous carbon matrices (such as petroleum coke, biomass, phenolic compounds, etc.) can alleviate the volume expansion of nano-silicon to a certain extent and improve structural stability; ② Enhanced conductive network, the high conductivity of carbon materials can improve the electron transport capability of the electrode, thereby improving rate performance.

[0004] Although progress has been made in silicon-carbon (Si / C) composite anode materials, the Si / C materials prepared by existing technologies still have the following problems: (1) The porous carbon materials used in existing silicon-carbon (Si / C) composite anode materials have insufficient carbon structure design, and the pores of the single-component porous carbon matrix are poorly formed (pore volume > 0.8 cm). 3After / g), the structural strength of the porous carbon will decrease, and it will be unable to effectively adapt to the volume change of nano-silicon. After long-term cycling, structural collapse and excessive expansion will still occur; (2) Poor interface stability. Nano-silicon is deposited inside the porous carbon by vapor deposition (CVD). Due to the many defects on the surface of the porous carbon and the different surface energies, nano-silicon will inevitably be deposited on its surface, which will cause the interface to consume too much active lithium to form an SEI layer. This will reduce the first coulombic efficiency and cycle performance of the silicon-carbon anode material. Summary of the Invention

[0005] The purpose of this invention is to address the problems of low structural strength and inability to effectively adapt to the volume changes of nano-silicon (Si / C) composite anode materials, which are currently used in the preparation of silicon-carbon (Si / C) composite anode materials. These problems include structural collapse and excessive volume expansion after long-term cycling, as well as poor interfacial stability, which reduces the initial coulombic efficiency and cycling performance of existing silicon-carbon composite anode materials. This invention proposes a novel method for preparing porous carbon / ordered carbon composite materials. The porous carbon / ordered carbon composite materials prepared by this method can replace existing porous carbon materials and be used together with silicon materials to prepare novel silicon-carbon composite anode materials, thereby solving the aforementioned problems of existing silicon-carbon (Si / C) composite anode materials.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] This invention provides a novel method for preparing porous carbon / ordered carbon composite materials, the method comprising the following steps:

[0008] S1. Disperse porous carbon to form a porous carbon dispersion;

[0009] S2. Adjust the porous carbon dispersion to acidity, and then add small molecule monomers and initiators to promote in-situ polymerization and coating of the small molecule monomers to form an ordered carbon precursor on the surface of the porous carbon.

[0010] S3. Perform solid-liquid separation, and then calcine the porous carbon coated with the ordered carbon precursor under a protective atmosphere so that the ordered carbon precursor is carbonized into an ordered carbon layer uniformly coated on the surface of the porous carbon, thereby obtaining a porous carbon / ordered carbon composite material.

[0011] The small molecule monomer is selected from one or more of the following: alkene / alkyne small molecule monomers, styrene small molecule monomers, acrylate small molecule monomers, bifunctional acid / alcohol small molecule monomers, cyclic small molecule monomers, polymer small molecule monomers, biocompatible small molecule monomers, cross-linked small molecule monomers, and naturally derived small molecule monomers.

[0012] Specifically, in step S2, the pH of the porous carbon dispersion can be adjusted to 1-3.

[0013] Furthermore, a method for preparing a novel porous carbon / ordered carbon composite material is provided: the porous carbon has a pore volume of 0.1–3.0 cm³. 3 / g, specific surface area of ​​1000~10000m² 2 / g; the pore volume of the porous carbon / ordered carbon composite material is 0.1–2.8 cm³. 3 / g, specific surface area of ​​1000~8000m² 2 / g. Preferably, the pore volume of the porous carbon is 0.2–2.5 cm³. 3 / g, specific surface area of ​​1000~5000m² 2 / g; preferably, the pore volume of the porous carbon / ordered carbon composite material is 0.3–1.5 cm³. 3 / g, specific surface area of ​​1000~3000m² 2 / g.

[0014] Furthermore, a method for preparing a novel porous carbon / ordered carbon composite material: the porous carbon content in the porous carbon dispersion in step S1 is 5.0–15.0 wt%.

[0015] Furthermore, a method for preparing a novel porous carbon / ordered carbon composite material is provided: in step S2, the weight ratio of small molecule monomer to porous carbon is (1-5):10; the weight ratio of initiator to porous carbon is (1-5):10.

[0016] Furthermore, a method for preparing a novel porous carbon / ordered carbon composite material is as follows: in step S3, the temperature is raised to 700-1500℃ for calcination, and after the temperature is raised, calcination is carried out for another 1-3 hours.

[0017] Furthermore, a method for preparing a novel porous carbon / ordered carbon composite material is provided: the olefin / alkyne-based small molecule monomers are selected from one or more of ethylene, propylene, butadiene, acetylene, vinyl chloride, and tetrafluoroethylene; the styrene-based small molecule monomers are selected from one or more of styrene and α-methylstyrene; the acrylate-based small molecule monomers are selected from one or more of methyl methacrylate and butyl acrylate; the bifunctional acid / alcohol small molecule monomers are selected from one or more of polyester monomers, polyamide monomers, polyurethane monomers, and epoxy resin monomers; the cyclic small molecule monomers are selected from one or more of ethylene oxide, caprolactone, and siloxane monomers; the polymeric small molecule monomers are selected from one or more of pyridine, aniline, acrylic acid, fluoroacrylates, and thiophene; the biocompatible small molecule monomers are selected from one or more of N-vinylpyrrolidone and hydroxyethyl methacrylate; the crosslinking small molecule monomer is selected from divinylbenzene; and the naturally derived small molecule monomers are selected from one or more of isoprene and glucose.

[0018] Furthermore, a method for preparing a novel porous carbon / ordered carbon composite material: the initiator is selected from one or more of peroxide initiators, azo compound initiators, persulfate system initiators, photoinitiators, cationic polymerization initiators, and anionic polymerization initiators.

[0019] Furthermore, a method for preparing a novel porous carbon / ordered carbon composite material: the peroxide initiator is selected from one or more of hydrogen peroxide, benzoyl peroxide, dicumyl peroxide, and tert-butyl peroxide; the azo compound initiator is selected from one or more of azobisisobutyronitrile and azobisisoheptanenitrile.

[0020] The persulfate system initiator is selected from one or more of potassium persulfate, sodium persulfate, ammonium persulfate, and potassium peroxymonosulfate; the photoinitiator is selected from one or more of benzoin dimethyl ether, isopropylthioxanthone, and ultraviolet light; the cationic polymerization initiator is selected from one or more of Lewis acid and protic acid; and the anionic polymerization initiator is selected from one or more of alkali metal organometallic compounds and alkali metals.

[0021] The present invention also provides a novel porous carbon / ordered carbon composite material, which is prepared by the above-mentioned preparation method. The porous carbon / ordered carbon composite material has porous carbon as the core, and its surface is coated with a layer of highly graphitized ordered carbon as the shell. At the same time, the internal cavities of the porous carbon core are also filled with ordered carbon.

[0022] The present invention also provides an application of a novel porous carbon / ordered carbon composite material, wherein the porous carbon / ordered carbon composite material prepared by the above preparation method is used as a carrier to prepare a novel silicon-carbon composite anode material together with silicon material.

[0023] The novel porous carbon / ordered carbon composite material prepared by this invention is a "porous carbon-ordered carbon" composite structure with porous carbon as the core and a highly graphitized ordered carbon layer as the shell. Simultaneously, most of the macropores within the porous carbon core are filled with ordered carbon, while the ultrapores within the porous carbon are sealed by ordered carbon to form closed pores. In other words, the novel porous carbon / ordered carbon composite material prepared by this invention is not only a core-shell structure of porous carbon@ordered carbon, but also has small-molecule ordered carbon filling the interior of the porous carbon. This enhances the mechanical strength, single-particle strength, and improves interfacial stability of the composite porous carbon (porous carbon / ordered carbon composite material).

[0024] The beneficial effects of this invention are:

[0025] The core of this invention's method for preparing a novel porous carbon / ordered carbon composite material lies in using in-situ coating technology to construct an ordered carbon coating layer with a highly ordered microcrystalline structure on the surface of a porous carbon framework, forming a "porous carbon-ordered carbon" composite carbon matrix structure. This constructed "porous carbon-ordered carbon" composite carbon matrix structure not only effectively enhances the overall structural strength of the porous carbon and maintains its mechanical stability, but also reduces active sites and improves interfacial stability after uniformly coating the surface with an ordered carbon layer. When this porous carbon / ordered carbon composite material is used together with silicon to prepare a novel silicon-carbon composite anode material, the initial coulombic efficiency and cycle performance of the silicon-carbon composite anode material can be improved. This solves the problems of structural collapse and excessive volume expansion that occur in existing silicon-carbon composite anode materials after long-term cycling, as well as the problems of poor initial coulombic efficiency and cycle performance of existing silicon-carbon composite anode materials.

[0026] This invention addresses the technical bottlenecks of existing silicon-carbon composite anode materials, such as poor interfacial stability, low initial coulombic efficiency, and large volume expansion rate. It innovatively proposes a method for constructing a carbon-based material with a "porous carbon-ordered carbon" composite structure. This technical solution achieves performance breakthroughs through the following innovations: ① Innovative structural design: In-situ polymerization technology is used to introduce small molecule carbon precursors into the interior of porous carbon to form a three-dimensional reinforcing network, thereby significantly improving the compressive strength of the material. At the same time, a highly graphitized ordered carbon coating layer is constructed on the surface of porous carbon, which significantly reduces the surface defect density and improves interfacial stability.

[0027] ② Performance Enhancement Mechanism: Existing technologies for preparing silicon-carbon composite anode materials mainly employ two pore-forming methods: steam and alkali activation. These methods suffer from the following technical drawbacks: First, precise control of pore size is difficult, leading to an unreasonable distribution of ultrapores, micropores, mesopores, and macropores. Second, the etching effect of pore-forming agents on porous carbon weakens its structural strength, easily resulting in structural collapse and rapid capacity decay during long-term cycling. In contrast, this invention utilizes in-situ polymerization technology to introduce small-molecule carbon precursors into the interior of porous carbon to construct an internal three-dimensional reinforced porous carbon network. This not only effectively confines the expansion of nano-silicon through spatial confinement but also... The micropores are also sealed to form a closed-pore structure, providing additional buffer space for the volume expansion of silicon particles, thereby significantly improving the stability and mechanical strength of the porous carbon / ordered carbon composite structure. Therefore, after preparing silicon-carbon composite anode materials, the overall expansion rate of the silicon-carbon composite anode materials can be effectively reduced. In addition, in view of the problem that traditional porous carbon has many surface defects and serious side reactions, which leads to the reduction of the first efficiency and interface stability of existing silicon-carbon anode materials, the surface ordered carbon layer introduced in this invention can effectively inhibit the electrolyte decomposition reaction and promote the formation of a stable ultrathin SEI film, thereby significantly improving the first coulombic efficiency of the obtained novel silicon-carbon composite anode material.

[0028] ③ Process advantages: The preparation method of this novel porous carbon / ordered carbon composite material can directly carry out in-situ polymerization of ordered carbon precursor and heat treatment passivation (calcination) through an integrated preparation process. The process is simple, has broad application prospects, and is easy to scale up. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 X-ray diffraction pattern of the novel porous carbon / ordered carbon composite material prepared in Example 1 of this invention;

[0031] Figure 2 The image shows a scanning electron microscope (SEM) image of the novel porous carbon / ordered carbon composite material prepared in Example 1 of this invention.

[0032] Figure 3 This is a transmission electron microscope (TEM) image of the novel porous carbon / ordered carbon composite material prepared in Example 1 of the present invention;

[0033] Figure 4 The image shows the single-particle strength test results of the novel porous carbon / ordered carbon composite material prepared in Example 1 of this invention.

[0034] Figure 5 This is a single-particle strength test diagram of the porous carbon used in Example 1 of the present invention;

[0035] Figure 6 The image shows a scanning electron microscope (SEM) image of the novel porous carbon / ordered carbon composite material prepared for Comparative Example 1. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment 1 provides a method for preparing a novel porous carbon / ordered carbon composite material, which includes the following steps:

[0039] S1, 100.0g, pore volume 1.1cm 3 / g of porous carbon material is dispersed in 1000.0ml of pure water to form a porous carbon dispersion.

[0040] S2. Adjust the pH of the porous carbon dispersion to 1, and then gradually add 15.0g of aniline monomer (small molecule polymer monomer) to the porous carbon dispersion while stirring at 300rpm to obtain a mixed solution of porous carbon and aniline monomer. Place the solution in a constant temperature reaction chamber and control the temperature at 0℃. Dissolve 30.0g of ammonium persulfate (sulfate system initiator) in 200ml of water and stir at 300rpm until the ammonium persulfate is completely dissolved. Then add all the ammonium persulfate solution to the above mixed solution and stir continuously at 300rpm for 6 hours in a constant temperature chamber at 0℃ to promote the in-situ polymerization and coating of aniline monomer, thereby forming an ordered carbon precursor layer on the surface of porous carbon, thus obtaining a suspension of porous carbon material coated by in-situ polymerization of small molecule ordered carbon precursor.

[0041] S3. The above suspension is separated into solid and liquid phases to obtain a porous carbon solid product with an ordered carbon precursor coated on its surface. The solid product is dried by forced air to remove surface moisture. Then, the solid product is placed in a nitrogen atmosphere (protective atmosphere) and heated to 800°C at a rate of 3°C / min. It is then calcined and pyrolyzed for 2 hours to carbonize the ordered carbon precursor, forming a uniformly coated ordered carbon layer (approximately 5.0 nm thick) on the porous carbon surface. This yields approximately 109 g of a novel porous carbon / ordered carbon composite material (a three-dimensional composite structure material of porous carbon and ordered carbon) with a pore volume of approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0042] The novel porous carbon / ordered carbon composite material prepared in Example 1 was characterized as follows: (1) X-ray diffraction (XRD) analysis: To analyze the degree of graphitization of the novel porous carbon / ordered carbon composite material prepared in Example 1, X-ray diffraction was performed, and the results are as follows. Figure 1 As shown: The results show that the ordered carbon content in the porous carbon / ordered carbon composite material is about 8.26 wt%. There is a significant increase in the ordered graphite peak near the diffraction angle (2θ) 26.5°, indicating that compared with the untreated porous carbon, the porous carbon / ordered carbon composite material prepared in Example 1 contains ordered carbon with a high degree of graphitization.

[0043] (2) Scanning electron microscopy (SEM) analysis: To analyze the microstructure of the surface of the novel porous carbon / ordered carbon composite material prepared in Example 1 above, scanning electron microscopy (SEM) was used. The results are as follows: Figure 2 As shown: From Figure 2 The microscopic images of the porous carbon / ordered carbon composite material shown clearly show an ordered carbon coating on the surface of the porous carbon particles, further proving the existence of ordered carbon.

[0044] (3) Transmission electron microscopy (TEM) analysis: To analyze the carbon composition on the surface of the novel porous carbon / ordered carbon composite material prepared in Example 1 above, transmission electron microscopy (TEM) was used. The results are as follows: Figure 3 As shown: The results show that the surface of the novel porous carbon / ordered carbon composite material is coated with an ordered carbon layer with a thickness of about 5.0 nm. The structure of the ordered carbon tends to be ordered, while the structure of the internal porous carbon tends to be disordered, which further confirms that the carbon layer coated on the surface is an ordered carbon layer structure with high graphitization.

[0045] (4) Single-particle strength analysis: To analyze the structural strength of the novel porous carbon / ordered carbon composite material prepared in Example 1 above, a single-particle mechanical testing system was used for analysis, and the results are as follows: Figure 4 and Figure 5 As shown, the results indicate that the single-particle strength of the novel porous carbon / ordered carbon composite material is approximately 196.8 MPa, while the single-particle strength of the unmodified porous carbon (i.e., porous carbon without ordered carbon filling and coating treatment) is approximately 30.2 MPa. This demonstrates that the present invention, by employing in-situ polymerization technology to introduce small molecule carbon precursors into the interior of porous carbon to form a three-dimensional reinforcing network, and simultaneously coating the surface of porous carbon with an ordered carbon layer, can significantly improve the compressive strength of the material.

[0046] Example 2

[0047] The difference between Example 2 and Example 1 is that the pore volume and specific surface area of ​​the porous carbon used in Example 2 are different from those in Example 1, while the other conditions are the same. The pore volume of the porous carbon used in Example 2 is 0.3 cm³. 3 / g; The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 2 is approximately 0.2 cm³. 3 / g, specific surface area is approximately 1200m² 2 / g.

[0048] Example 3

[0049] The difference between Example 3 and Example 1 is that the pore volume and specific surface area of ​​the porous carbon used in Example 3 are different from those in Example 1, while the other conditions are the same. The pore volume of the porous carbon used in Example 3 is 3.0 cm³. 3 / g; The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 3 is approximately 2.5 cm³. 3 / g, specific surface area is approximately 3000m² 2 / g.

[0050] Example 4

[0051] The difference between Example 4 and Example 1 is that the small molecule monomer used in Example 4 is different from that in Example 1; pyrrole monomer (cyclic small molecule monomer) is used in Example 4, while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 4 is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0052] Example 5

[0053] The difference between Example 5 and Example 1 is that the small molecule monomer used in Example 5 is different from that in Example 1; fluorinated acrylate monomers (polymer small molecule monomers) are used in Example 5, while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 5 is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0054] Example 6

[0055] The difference between Example 6 and Example 1 is that the small molecule monomers used in Example 6 are different from those in Example 1. Example 6 uses a 1:1 mass ratio of fluoroacrylate monomers and acrylic monomers (polymer small molecule monomers), while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 6 is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0056] Example 7

[0057] The difference between Example 7 and Example 1 is that the small molecule monomer used in Example 7 is different from that in Example 1; Example 7 uses styrene monomer (styrene-based small molecule monomer), while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 7 is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0058] Example 8

[0059] The difference between Example 8 and Example 1 is that the small molecule monomer used in Example 8 is different from that in Example 1; in Example 8, a polyamide monomer (a bifunctional acid / alcohol small molecule monomer) is used, while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 8 is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0060] Example 9

[0061] The difference between Example 9 and Example 1 is that the small molecule monomer used in Example 9 is different from that in Example 1; Example 9 uses ethylene oxide monomer (cyclic small molecule monomer), while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 9 is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0062] Example 10

[0063] The difference between Example 10 and Example 1 is that the small molecule monomer used in Example 10 is different from that in Example 1; Example 10 uses hydroxyethyl methacrylate monomer (a biocompatible small molecule monomer), while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 10 is approximately 0.9 cm³. 3 / g, specific surface area approximately 1900m² 2 / g.

[0064] Example 11

[0065] The difference between Example 11 and Example 1 is that the small molecule monomer used in Example 11 is different from that in Example 1; Example 11 uses a divinylbenzene monomer (a cross-linked small molecule monomer), while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 11 is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0066] Example 12

[0067] The difference between Example 12 and Example 1 is that the small molecule monomer used in Example 12 is different from that in Example 1; Example 12 uses isoprene monomer (crosslinked small molecule monomer), while the other conditions are the same as in Example 1. The pore volume of the novel porous carbon / ordered carbon composite material obtained in Example 12 is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0068] Example 13

[0069] The difference between Example 13 and Example 1 is that the calcination temperature in Example 13 is different from that in Example 1. In Example 13, the carbonization of the ordered carbon precursor was carried out by calcination at 1500℃, while the other conditions were the same as in Example 1. The novel porous carbon / ordered carbon composite material obtained in Example 13 has an ordered carbon content of approximately 0.54 wt%, a coating thickness of approximately 3.7 nm on the porous carbon surface, and a pore volume of approximately 0.88 cm³. 3 / g, specific surface area is approximately 1890m² 2 / g.

[0070] Example 14

[0071] The difference between Example 14 and Example 1 is that the calcination temperature in Example 14 is different from that in Example 1. In Example 14, the carbonization of the ordered carbon precursor was carried out by calcination at 700°C, while the other conditions were the same as in Example 1. The novel porous carbon / ordered carbon composite material obtained in Example 14 has an ordered carbon content of approximately 0.8 wt%, a coating thickness of approximately 5.5 nm on the porous carbon surface, and a pore volume of approximately 0.81 cm³. 3 / g, specific surface area is approximately 1990m² 2 / g.

[0072] Example 15

[0073] The difference between Example 15 and Example 1 is that the amount of small molecule monomer added in Example 15 is different from that in Example 1. In Example 15, 50.0 g of aniline monomer is gradually added to the porous carbon dispersion, while the other conditions are the same as in Example 1. The novel porous carbon / ordered carbon composite material obtained in Example 15 has an ordered carbon content of approximately 23.1 wt%, an ordered carbon layer coating thickness of approximately 13.5 nm on the porous carbon surface, and a pore volume of approximately 0.85 cm³. 3 / g, specific surface area is approximately 1780m² 2 / g.

[0074] Example 16

[0075] The difference between Example 16 and Example 1 is that the initiator used in Example 16 is different from that in Example 1; hydrogen peroxide (a peroxide-based initiator) is used as the initiator in Example 16, while the other conditions are the same as in Example 1. In the novel porous carbon / ordered carbon composite material obtained in Example 16, the ordered carbon content is approximately 8.25 wt%, the coating thickness of the ordered carbon layer on the porous carbon surface is approximately 5.0 nm, and the pore volume of this porous carbon / ordered carbon composite material is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0076] Example 17

[0077] The difference between Example 17 and Example 1 is that the initiator used in Example 17 is different from that in Example 1; azobisisobutyronitrile (azo compound initiator) was used as the initiator in Example 17, while the other conditions were the same as in Example 1. In the novel porous carbon / ordered carbon composite material obtained in Example 17, the ordered carbon content is approximately 8.24 wt%, the coating thickness of the ordered carbon layer on the porous carbon surface is approximately 4.9 nm, and the pore volume of this porous carbon / ordered carbon composite material is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0078] Example 18

[0079] The difference between Example 18 and Example 1 is that the initiator used in Example 18 is different from that in Example 1; isopropylthioxanthone (photoinitiator) was used as the initiator in Example 18, while the other conditions were the same as in Example 1. In the novel porous carbon / ordered carbon composite material obtained in Example 18, the ordered carbon content is 8.25 wt%, the coating thickness of the ordered carbon layer on the porous carbon surface is approximately 5.0 nm, and the pore volume of this porous carbon / ordered carbon composite material is approximately 0.9 cm³. 3 / g, specific surface area is approximately 1900m² 2 / g.

[0080] Example 19

[0081] The difference between Example 19 and Example 1 is that the initiator used in Example 19 is different from that in Example 1; a protic acid (cationic polymerization initiator) is used as the initiator in Example 19, while the other conditions are the same as in Example 1. The novel porous carbon / ordered carbon composite material obtained in Example 19 contains approximately 8.2 wt% ordered carbon, and the coating thickness of the ordered carbon layer on the porous carbon surface is approximately 4.5 nm. The pore volume of this porous carbon / ordered carbon composite material is approximately 0.93 cm³. 3 / g, specific surface area is approximately 1980m² 2 / g.

[0082] Example 20

[0083] The difference between Example 20 and Example 1 is that the initiator used in Example 20 is different from that in Example 1; sodium persulfate is used as the initiator in Example 20, while the other conditions are the same as in Example 1. The novel porous carbon / ordered carbon composite material obtained in Example 20 contains approximately 8.21 wt% ordered carbon, the coating thickness of the ordered carbon layer on the porous carbon surface is approximately 4.8 nm, and the pore volume of this porous carbon / ordered carbon composite material is approximately 0.85 cm³. 3 / g, specific surface area approximately 1920m² 2 / g.

[0084] Example 21

[0085] The difference between Example 21 and Example 1 is that the amount of initiator added in Example 21 is different from that in Example 1, while the other conditions are the same. In Example 21, 48.0 g of ammonium persulfate was dissolved in 200 ml of water and then completely added to the mixed solution of porous carbon and aniline monomer. The novel porous carbon / ordered carbon composite material obtained in Example 21 has an ordered carbon content of approximately 8.3 wt%, an ordered carbon layer coating thickness of approximately 5.1 nm on the porous carbon surface, and a pore volume of approximately 0.87 cm³. 3 / g, specific surface area is 1860m² 2 / g.

[0086] Comparative Example 1

[0087] The difference between Comparative Example 1 and Example 1 is that the amount of small molecule monomer added in Comparative Example 1 is different from that in Example 1. In Comparative Example 1, 200.0 g of aniline monomer (excess) was gradually added to the porous carbon dispersion, while the other conditions were the same as in Example 1. The novel porous carbon / ordered carbon composite material obtained in Comparative Example 1 has an ordered carbon content of approximately 54.5 wt%, an ordered carbon layer coating thickness of approximately 33.2 nm on the porous carbon surface, and a pore volume of approximately 0.15 cm³. 3 / g, specific surface area is approximately 290m² 2 / g.

[0088] Scanning electron microscopy (SEM) analysis was performed on the porous carbon / ordered carbon composite material prepared in Comparative Example 1 above: To analyze the surface microstructure of the porous carbon / ordered carbon composite material prepared in Comparative Example 1 above, scanning electron microscopy (SEM) was used for analysis, and the results are as follows: Figure 6 As shown, a thick ordered carbon layer is clearly found on the surface of the porous carbon particles. This results in the porous carbon inside being completely covered. Subsequently, when preparing silicon-carbon composite anode materials with silicon materials, the silicon particles cannot be effectively embedded into the porous carbon materials, resulting in poor performance of the obtained silicon-carbon materials.

[0089] Comparative Example 2

[0090] The difference between Comparative Example 2 and Example 1 is that no ammonium persulfate initiator was added in Comparative Example 2, while the other conditions were the same as in Example 1. Comparative Example 2 failed to obtain an ordered carbon layer coated on the surface of porous carbon.

[0091] The core of this invention's method for preparing a novel porous carbon / ordered carbon composite material lies in the in-situ coating technique used to construct an ordered carbon coating layer with a highly ordered microcrystalline structure on the surface of a porous carbon framework. Furthermore, small-molecule carbon precursors are introduced into the porous carbon to construct an internal three-dimensional reinforced porous carbon network, forming a "porous carbon-ordered carbon" composite carbon matrix structure. This constructed three-dimensional reinforced network not only effectively enhances the overall structural strength of the porous carbon and maintains its mechanical stability, but the uniformly coated ordered carbon layer also reduces active sites and improves interfacial stability. Therefore, after preparing a novel silicon-carbon composite anode material by combining this novel porous carbon / ordered carbon composite material with silicon, the structural strength, initial coulombic efficiency, and cycle performance of the silicon-carbon composite anode material can be improved. This solves the problems of structural collapse and excessive volume expansion that occur in existing silicon-carbon composite anode materials after long-term cycling, as well as the poor initial coulombic efficiency and cycle performance of existing silicon-carbon composite anode materials.

[0092] The above-described preferred embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the invention. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a novel porous carbon / ordered carbon composite material, characterized in that, The method includes the following steps: S1. Disperse porous carbon to form a porous carbon dispersion; S2. Adjust the porous carbon dispersion to acidity, and then add small molecule monomers and initiators to promote in-situ polymerization and coating of the small molecule monomers to form an ordered carbon precursor on the surface of the porous carbon. S3. Perform solid-liquid separation, and then calcine the porous carbon coated with the ordered carbon precursor under a protective atmosphere so that the ordered carbon precursor is carbonized into an ordered carbon layer uniformly coated on the surface of the porous carbon, thereby obtaining a porous carbon / ordered carbon composite material. The small molecule monomer is selected from one or more of the following: alkene / alkyne small molecule monomers, styrene small molecule monomers, acrylate small molecule monomers, bifunctional acid / alcohol small molecule monomers, cyclic small molecule monomers, polymer small molecule monomers, biocompatible small molecule monomers, cross-linked small molecule monomers, and naturally derived small molecule monomers.

2. The method for preparing a novel porous carbon / ordered carbon composite material according to claim 1, characterized in that, The porous carbon has a pore volume of 0.1–3.0 cm³. 3 / g, specific surface area of ​​1000~10000m² 2 / g; The porous carbon / ordered carbon composite material has a pore volume of 0.1–2.8 cm³. 3 / g, specific surface area of ​​1000~8000m² 2 / g.

3. The method for preparing a novel porous carbon / ordered carbon composite material according to claim 1, characterized in that, The porous carbon content in the porous carbon dispersion in step S1 is 5.0–15.0 wt%.

4. The method for preparing a novel porous carbon / ordered carbon composite material according to claim 1, characterized in that, In step S2, the weight ratio of small molecule monomer to porous carbon is (1-5):10; the weight ratio of initiator to porous carbon is (1-5):

10.

5. The method for preparing a novel porous carbon / ordered carbon composite material according to claim 1, characterized in that, In step S3, the temperature is raised to 700-1500℃ for calcination, and the calcination time after the temperature is raised is 1-3 hours.

6. The method for preparing a novel porous carbon / ordered carbon composite material according to claim 1, characterized in that, The olefin / alkyne small molecule monomers are selected from one or more of ethylene, propylene, butadiene, acetylene, vinyl chloride, and tetrafluoroethylene; The styrene-based small molecule monomers are selected from one or more of styrene and α-methylstyrene; the acrylate small molecule monomers are selected from one or more of methyl methacrylate and butyl acrylate. The bifunctional acid / alcohol small molecule monomer is selected from one or more of polyester monomers, polyamide monomers, polyurethane monomers, and epoxy resin monomers; the cyclic small molecule monomer is selected from one or more of ethylene oxide, caprolactone, siloxane monomers, and pyrrole monomers. The polymer monomer is selected from one or more of pyridine, aniline, acrylic acid, fluoroacrylate, and thiophene; the biocompatible monomer is selected from one or more of N-vinylpyrrolidone and hydroxyethyl methacrylate. The cross-linked small molecule monomer is selected from divinylbenzene; the naturally sourced small molecule monomer is selected from one or more of isoprene and glucose.

7. The method for preparing a novel porous carbon / ordered carbon composite material according to claim 1, characterized in that, The initiator is selected from one or more of the following: peroxide initiators, azo compound initiators, persulfate system initiators, photoinitiators, cationic polymerization initiators, and anionic polymerization initiators.

8. The method for preparing a novel porous carbon / ordered carbon composite material according to claim 7, characterized in that, The peroxide initiator is selected from one or more of hydrogen peroxide, benzoyl peroxide, dicumyl peroxide, and tert-butyl peroxide; The azo compound initiator is selected from one or more of azobisisobutyronitrile and azobisisoheptanenitrile; the persulfate system initiator is selected from one or more of potassium persulfate, sodium persulfate, ammonium persulfate, and potassium peroxymonosulfate. The photoinitiator is selected from one or more of benzoin dimethyl ether, isopropylthioxanthone, and ultraviolet light; the cationic polymerization initiator is selected from one or more of Lewis acid and protic acid; and the anionic polymerization initiator is selected from one or more of alkali metal organometallic compounds and alkali metals.

9. A novel porous carbon / ordered carbon composite material, characterized in that, The porous carbon / ordered carbon composite material is prepared by any one of the preparation methods described in claims 1 to 8, wherein the porous carbon is used as the core and the surface is coated with a layer of highly graphitized ordered carbon as the shell.

10. The use of a novel porous carbon / ordered carbon composite material, characterized in that, The porous carbon / ordered carbon composite material prepared by the preparation method according to any one of claims 1 to 8 is used as a carrier to prepare a novel silicon-carbon composite anode material with silicon material.

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