Carbon-based composite material for negative electrode of secondary battery and preparation method of carbon-based composite material
By preparing porous carbon matrix composite with high-expanded negative electrode active material to form a porous structure, the problem of poor pore capacity, pore size and surface characteristics of existing carbon matrix composite materials in lithium-ion or sodium ion batteries is solved, and the first effect, specific capacity and cycle stability of the battery are improved.
Patent Information
- Application Number
- CN202311865571.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2025-07-01
AI Technical Summary
The existing carbon-based composite materials have poor pore capacity, pore size and surface characteristics in lithium-ion or sodium-ion batteries, resulting in unsatisfactory silicon deposition effect, affecting capacity performance and product consistency, and the post-treatment process cost is high and uncontrollable.
The porous carbon matrix is prepared by pyrolysis treatment of metal organic framework materials, and is composited with the highly expanded negative electrode active material to form a porous carbon matrix composite material. Carbon coating and conductive polymer coating are carried out through CVD method or fluidized bed method to optimize the dispersion and structural stability of the material.
The first-effect and specific capacity of the battery are improved, the electrode volume expansion is reduced, the cycle stability is improved, and the controllable deposition and structural relief of highly expanded negative electrode active materials are achieved.
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Figure CN120237170A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of secondary batteries, and particularly relates to a carbon-based composite material for a secondary battery anode and a preparation method thereof. Background Art
[0002] Currently, the carbon matrix in carbon-based composite materials used in lithium-ion or sodium-ion battery systems is mainly based on materials such as polymers and biomass. Although this type of material has certain advantages in terms of raw material cost, subsequent processes such as pore formation and surface treatment will increase costs in other aspects. In addition, it is still unclear and uncontrollable whether the post-treatment process for such materials can meet the requirements of product performance indicators, and a large number of cross-experiments are needed for verification. Taking silicon-carbon composite materials as an example, the pore volume, pore diameter, and surface characteristics of the carbon matrix material seriously affect the subsequent silicon deposition effect, and thus affect the actual capacity performance and product consistency of silicon-carbon products. Therefore, it is necessary to develop a suitable porous carbon matrix, realize the controllable composite of silicon-based materials, and synthesize a carbon-based composite material with high initial efficiency, high specific capacity, low expansion, and long cycle life. Summary of the Invention
[0003] The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an embodiment of the present invention provides a carbon-based composite material for a secondary battery anode and a preparation method thereof.
[0004] The embodiment of the present invention provides a preparation method of a carbon-based composite material for a secondary battery anode, comprising the following steps:
[0005] (1) Pyrolyzing a metal-organic framework material to obtain a porous carbon matrix;
[0006] (2) Compositing the porous carbon matrix with a high-expansion anode active material to obtain the carbon-based composite material.
[0007] The advantages and technical effects brought by the preparation method of the carbon-based composite material for a secondary battery anode according to the embodiment of the present invention are as follows:
[0008] 1. After the pyrolysis treatment of the metal-organic framework material in step (1), a porous carbon matrix can be obtained. The porous carbon matrix has a highly fractal structure, and subsequent controllable deposition of the high-expansion anode active material can be realized;
[0009] 2. In step (2), the porous carbon matrix is composited with the high-expansion anode active material. The obtained carbon-based composite material has a porous structure, which can relieve the structural rupture at the particle level caused by the volume expansion of the high-expansion anode active material and improve the cycling performance of the electrode material.
[0010] In some embodiments, in step (1), the metal-organic framework material is selected from at least one of reticular metal-organic framework materials, zeolitic imidazolate framework materials, and Levasil framework materials; and / or, the central atom of the metal-organic framework material is selected from at least one of Zn, Cu, Fe, Co, Ni, Mg, and La.
[0011] In some embodiments, in step (1), the metal-organic framework material is a reticular metal-organic framework material. Preferably, and / or, the central atom of the metal-organic framework material is at least one of Zn, Mg, Cu, and Fe.
[0012] In some embodiments, in step (1), the pyrolysis treatment is carried out in a vacuum or a protective atmosphere; and / or, the temperature of the pyrolysis treatment is 750 - 1500 °C; and / or, the time of the pyrolysis treatment is 1 - 8 h.
[0013] In some embodiments, in step (1), the temperature of the pyrolysis treatment is 900 - 1400 °C; and / or, the time of the pyrolysis treatment is 2 - 6 h.
[0014] In some embodiments, in step (1), the specific surface area of the porous carbon matrix is 500 - 3000 m 2 / g; and / or, the pore volume of the porous carbon matrix is 0.7 - 1.2 cm 3 / g; the pore diameter of the porous carbon matrix is 2 - 1000 nm; and / or, the surface fractal dimension of the porous carbon matrix is 2 - 3.
[0015] In some embodiments, in step (1), the specific surface area of the porous carbon matrix is 1500 - 2000 m 2 / g; and / or, the pore volume of the porous carbon matrix is 0.8 - 0.9 cm 3 / g; and / or, the pore diameter of the porous carbon matrix is 2 - 200 nm; and / or, the surface fractal dimension of the porous carbon matrix is 2.2 - 2.7.
[0016] In some embodiments, in step (1), after the pyrolysis treatment, an acid washing treatment is further carried out to obtain a porous carbon matrix.
[0017] In some embodiments, in step (2), the high-expansion anode active material is selected from at least one of elemental Si, P, Ge, SiO x (0 < x ≤ 2), PO y (0 < y ≤ 2.5), GeO z (0 < z ≤ 2), and SnO u (0 < u ≤ 2).
[0018] In some embodiments, in step (2), the high-expansion negative electrode active material is Si.
[0019] In some embodiments, in step (2), the composite is carried out by chemical vapor deposition (CVD), fluidized bed method, sol-gel method or hydrothermal method.
[0020] In some embodiments, in step (2), the composite is carried out by chemical vapor deposition (CVD) or fluidized bed method.
[0021] In some embodiments, in step (2), the mass ratio of the porous carbon matrix to the high-expansion negative electrode active material is 1:4 - 5:1.
[0022] In some embodiments, the preparation method further includes step (3) after the composite, carbon coating and / or conductive polymer coating are carried out to obtain the carbon-based composite material.
[0023] In some embodiments, in step (3), the carbon source used for the carbon coating is selected from at least one of pitch, resin, glucose, methane and acetylene; and / or, the conductive polymer includes at least one of polydopamine, polyaniline and polyvinylpyrrolidone.
[0024] In addition, the embodiments of the present invention also provide a carbon-based composite material for the negative electrode of a secondary battery, which is prepared by the preparation method of the embodiments of the present invention.
[0025] The advantages and technical effects brought by the carbon-based composite material for the negative electrode of the secondary battery in the embodiments of the present invention are as follows:
[0026] The carbon-based composite material in the embodiments of the present invention can be used in liquid, semi-solid or all-solid battery systems. As the negative electrode active material, it can effectively improve the initial efficiency and specific capacity of the battery, reduce the volume expansion of the electrode and improve the cycle stability. Description of the Drawings
[0027] Figure 1 It is a diagram showing the difference in the cycle capacity retention rate of the lithium-ion batteries in Application Examples 1-2 and Application Comparative Example 1. Detailed Embodiments
[0028] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.
[0029] The embodiments of the present invention provide a preparation method of a carbon-based composite material for the negative electrode of a secondary battery, including the following steps:
[0030] (1) Thermally decompose the metal-organic framework material to obtain a porous carbon matrix;
[0031] (2) Compound the porous carbon matrix and the high-expansion anode active material to obtain the carbon-based composite material.
[0032] In step (1), the metal-organic framework material (MOF material) is a material formed by self-assembly of a metal source and an organic ligand through coordination to form a three-dimensional porous structure. After pyrolysis treatment of the MOF material, an ordered and developed porous carbon matrix can be obtained. In step (2), after the porous carbon matrix and the high-expansion anode active material are compounded, the high-expansion anode active material is loaded on the porous carbon matrix, which can not only isolate the high-expansion anode active material and improve its dispersion uniformity, but also the pores of the porous carbon matrix can provide a broad space for the expansion of the high-expansion anode active material during the lithium / sodium insertion / extraction process, effectively alleviating or suppressing the volume expansion effect caused by the lithium / sodium ion insertion or extraction process, and having good cycle stability.
[0033] In some embodiments, in step (1), the metal-organic framework material is selected from at least one of reticular metal-organic framework materials (IRMOFs), zeolitic imidazolate framework materials (ZIFs), and LeVasir framework materials (MILs), preferably reticular metal-organic framework materials (IRMOFs); and / or, the central atom of the metal-organic framework material is selected from at least one of Zn, Cu, Fe, Co, Ni, Mg, and La, preferably at least one of Zn, Mg, Cu, and Fe. By screening and matching the ligands and central atoms in the MOF material in step (1), a porous carbon matrix with adjustable structure and composition can be obtained after pyrolysis treatment. The morphology, pore volume, and pore diameter of this type of porous carbon matrix can be controlled and adjusted, which is convenient for the controllable compounding of the subsequent high-expansion anode active material, and thus realizes the preparation of high specific energy, long cycle, and high-safety battery cells.
[0034] In some embodiments, in step (1), the pyrolysis treatment is carried out in a vacuum or a protective atmosphere; preferably, the protective atmosphere is nitrogen or argon or a mixed gas of argon and hydrogen. A vacuum or a protective atmosphere is beneficial to the complete carbonization of the MOF material into a porous carbon matrix.
[0035] In some embodiments, in step (1), the temperature of the pyrolysis treatment is 750 - 1500 °C, such as 750 °C, 800 °C, 900 °C, 1000 °C, 1100 °C, 1200 °C, 1300 °C, 1400 °C, 1500 °C, etc., preferably 900 - 1400 °C; and / or, the time of the pyrolysis treatment is 1 - 8 h, such as 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, etc., preferably 2 - 6 h. Within the above temperature and time ranges, it is helpful for the complete carbonization of the MOF material into a porous carbon matrix.
[0036] In some embodiments, in step (1), the specific surface area of the porous carbon matrix is 500 - 3000 m 2 / g, such as 500 m 2 / g, 1000 m 2 / g, 1500 m 2 / g, 2000 m 2 / g, 2500 m 2 / g, 3000 m 2 / g, etc., preferably 1500 - 2000 m 2 / g; and / or, the pore volume of the porous carbon matrix is 0.7 - 1.2 cm 3 / g, such as 0.7 m 3 / g, 0.8 m 3 / g, 0.9 m 3 / g, 1 m 3 / g, 1.1 m 3 / g, 1.2 m 3 / g, etc., preferably 0.8 - 0.9 cm 3 / g; the pore diameter of the porous carbon matrix is 2 - 1000 nm, such as 2 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, etc., preferably 2 - 200 nm; and / or, the surface fractal dimension of the porous carbon matrix is 2 - 3, such as 2, 2.2, 2.4, 2.6, 2.8, 3, etc., preferably 2.2 - 2.7. A porous carbon matrix that meets the above specific surface area, pore volume, pore diameter, and surface fractal dimension is beneficial for providing more anchoring structure sites for the loaded material, so as to improve its attachment stability in the porous carbon matrix, and further improve the cycle stability of the carbon-based composite material.
[0037] In some embodiments, in step (1), after the pyrolysis treatment, an acid washing treatment is further performed to obtain a porous carbon matrix. The acid washing treatment helps to remove metal oxides in the porous carbon matrix, provides more anchoring structure sites for the loaded material, improves its attachment stability in the porous carbon matrix, and further improves the cycle stability of the carbon-based composite material.
[0038] In some embodiments, in step (2), the high-expansion anode active material is selected from at least one of elemental Si, P, Ge, SiO x (0 < x ≤ 2), PO y (0 < y ≤ 2.5), GeO z (0 < z ≤ 2), and SnO u (0 < u ≤ 2), preferably Si. The above-listed high-expansion anode active materials help to improve the capacity of the carbon-based composite material.
[0039] In some embodiments, in step (2), the composite is carried out by chemical vapor deposition (CVD), fluidized bed method, sol-gel method or hydrothermal method, preferably CVD method or fluidized bed method.
[0040] In some embodiments, in step (2), the mass ratio of the porous carbon matrix to the high-expansion anode active material is 1:4 - 5:1, such as 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, etc. Within the above range, this ratio helps to achieve complete coating of the high-expansion anode active material and adsorb and fix its pulverized products during the cycling process.
[0041] In some embodiments, it further includes step (3) after the composite, carbon coating and / or conductive polymer coating are carried out to obtain the carbon-based composite material.
[0042] The carbon coating can be specifically carried out in the following manner. For example, a carbon source is chemically vapor deposited (CVD) on the surface of the carbon-based composite material obtained in step (2) at 900 - 1200 °C to form a carbon coating layer; or, the carbon-based composite material obtained in step (2) and a carbon source are mixed and calcined at 800 - 1200 °C to form the carbon-based coating layer on the surface of the carbon-based composite material obtained in step (2).
[0043] In some embodiments, in step (2), based on the total mass of the carbon-based composite material being 100%, the mass fraction of carbon is 20 - 80%, preferably 40 - 60%.
[0044] In some embodiments, in step (3), the carbon source for the carbon coating is selected from at least one of pitch, resin, glucose, methane and acetylene. The carbon coating layer can improve the conductivity of the silicon-based composite material.
[0045] In some embodiments, in step (3), the conductive polymer includes at least one of polydopamine, polyaniline and polyvinylpyrrolidone. Carrying out the conductive polymer coating helps to improve the strength of the porous carbon matrix to avoid rupture of the porous carbon matrix caused by the volume change of the high-expansion anode active material during the cycling process.
[0046] In some embodiments, in step (3), based on the total mass of the carbon-based composite material being 100%, the mass fraction of the coating layer (carbon coating layer and / or conductive polymer coating layer) is 0.1-5%, such as 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. When the mass fraction of the coating layer is too low, it is not conducive to improving the conductivity or strength of the carbon-based composite material. When the mass fraction of the coating layer is too high, the content of other components will be too low, which is not conducive to improving the cycle stability of the battery. Preferably, based on the total mass of the carbon-based composite material being 100%, the mass fraction of the coating layer (carbon coating layer and / or conductive polymer coating layer) is 1-3%.
[0047] In addition, the embodiments of the present invention also provide a carbon-based composite material for the negative electrode of a secondary battery, which is prepared by the preparation method of the embodiments of the present invention.
[0048] The carbon-based composite material of the embodiments of the present invention can be used in liquid, semi-solid or all-solid battery systems. As the negative electrode active material, it can effectively improve the initial efficiency and specific capacity of the battery, reduce the volume expansion of the electrode, and improve the cycle stability.
[0049] The present invention will be described in detail below with reference to the embodiments and the drawings.
[0050] Example 1
[0051] A preparation method of a carbon-based composite material for the negative electrode of a secondary battery includes the following steps:
[0052] (1) The reticular metal-organic framework material (IRMOF-9) with Zn as the central atom (manufacturer: CHEMSOON, brand CAS No.: 473981-45-2) is pyrolyzed in an argon atmosphere at 1200 °C for 4 h to obtain a porous carbon matrix; the specific surface area of the porous carbon matrix is 1470 m 2 / g, the pore volume is 1.26 cm 3 / g, the pore diameter is 3.4 nm, and the surface fractal dimension is 2.45; and the porous carbon matrix obtained by pyrolyzing MOF-74(Zn) is pickled with 1 mol / L dilute hydrochloric acid to remove the metal oxides therein;
[0053] (2) 2 g of the porous carbon matrix obtained in step (1) and 2 g of nano-silicon are compounded by mechanical mixing to obtain carbon-based composite material A; based on the total mass of carbon-based composite material A being 100%, the mass fraction of carbon is 50%;
[0054] (3) Using the CVD method, with methane gas as the carbon source, the methane partial pressure is 10 kPa, the argon partial pressure is 85 kPa, and the hydrogen partial pressure is 5 kPa. A deposition reaction is carried out on the surface of the carbon-based composite material A obtained in step (2) at 1100 °C for 1.5 h of heat preservation, and a carbon coating layer is coated on the surface of the carbon-based composite material A obtained in step (2) to obtain a carbon-based composite material B; based on the total mass of the carbon-based composite material B obtained in this step being 100%, the mass fraction of the carbon coating layer is 2.5%.
[0055] Application Example 1
[0056] A method for preparing a lithium-ion battery includes the following steps: Weigh 92 mg of the carbon-based composite material B obtained in step (3) of Example 1, add 160 mg of a 5% PVDF solution (the solvent is NMP), add an appropriate amount of NMP to adjust the viscosity of the slurry, stir for 1 h, and the solid content of the obtained negative electrode slurry is 40%. Transfer the stirred negative electrode slurry onto a flat copper foil, use a 100 μm doctor blade to scrape, and vacuum dry at 50 °C for 12 h to obtain a negative electrode sheet; the electrolyte uses 1.0 mol·L -1 of LiClO4-EC / DMC; Assemble a lithium-ion battery in an argon glove box, from top to bottom are the negative electrode shell, nickel foam, lithium sheet, glass fiber separator, negative electrode sheet, and positive electrode shell.
[0057] Example 2
[0058] A method for preparing a carbon-based composite material for a secondary battery negative electrode includes the following steps:
[0059] (1) Select a reticular metal-organic framework material (MOF-74(Mg)) with Mg as the central atom (manufacturer: CHEMSOON, brand CAS No.: 1565828-96-7) and carry out pyrolysis treatment in an argon atmosphere at 1200 °C for 4 h to obtain a porous carbon matrix; the specific surface area of the porous carbon matrix is 1245 m 2 / g, the pore volume is 1.6 cm 3 / g, the pore diameter is 1.9 nm, and the surface fractal dimension is 2.44; and use 1 mol / L dilute hydrochloric acid to pickle the porous carbon matrix obtained after the pyrolysis treatment of MOF-74(Mg) to remove the metal oxides therein;
[0060] (2) Mechanically mix 2 g of the porous carbon matrix obtained in step (1) and 2 g of nanosilicon to obtain a carbon-based composite material A; based on the total mass of the carbon-based composite material A being 100%, the mass fraction of carbon is 50%;
[0061] (3) Using the CVD method, with methane gas as the carbon source, the methane partial pressure is 10 kPa, the argon partial pressure is 85 kPa, and the hydrogen partial pressure is 5 kPa. A deposition reaction is carried out on the surface of the carbon-based composite material A obtained in step (2) at 1100 °C, and heat preservation is carried out for 1.5 h. A carbon coating layer is coated on the surface of the carbon-based composite material A obtained in step (2) to obtain a carbon-based composite material B; based on the total mass of the carbon-based composite material B obtained in this step being 100%, the mass fraction of the carbon coating layer is 2.5%.
[0062] Application Example 2
[0063] The preparation method of the lithium-ion battery in this application example is the same as that in Application Example 1, except that the carbon-based composite material B obtained in step (3) of Example 2 is used.
[0064] Example 3
[0065] The preparation method of this example is the same as that of Example 1, except that in step (1), pyrolysis treatment is carried out at 1000 °C for 3 h; the specific surface area of the obtained porous carbon matrix is 2350 m 2 / g, the pore volume is 2.48 cm 3 / g, the pore diameter is 4.2 nm, and the surface fractal dimension is 2.36.
[0066] Application Example 3
[0067] The preparation method of the lithium-ion battery in this application example is the same as that in Application Example 1, except that the carbon-based composite material B obtained in step (3) of Example 3 is used.
[0068] Example 4
[0069] The preparation method of this example is the same as that of Example 1, except that in step (2), 2 g of porous carbon matrix and 2 g of nanosilicon are compounded by mechanical mixing to obtain a carbon-based composite material A; based on the total mass of the carbon-based composite material A obtained in this step being 100%, the mass fraction of carbon is 50%; step (3) is omitted.
[0070] Application Example 4
[0071] The preparation method of the lithium-ion battery in this application example is the same as that in Application Example 1, except that the carbon-based composite material A obtained in step (2) of Example 4 is used.
[0072] Example 5
[0073] The preparation method of this example is the same as that of Example 1, except that in step (3), 2 g of the carbon-based composite material obtained in step (2) is dispersed in a buffer solution with a pH of 8.5, 0.2 g of dopamine is added, and the mixture is stirred for 18 h to coat a polydopamine coating layer on the surface of the carbon-based composite material A, obtaining carbon-based composite material B; based on the total mass of the carbon-based composite material B obtained in this step being 100%, the mass fraction of the carbon coating layer is 2%.
[0074] Application Example 5
[0075] The preparation method of the lithium-ion battery in this application example is the same as that of Application Example 1, except that the carbon-based composite material B obtained in step (3) of Example 5 is used.
[0076] Comparative Example 1
[0077] A preparation method of a carbon-based composite material for a secondary battery negative electrode includes the following steps:
[0078] (1) 2 g of carbon black (SP) and 2 g of nano-silicon are compounded by mechanical mixing to obtain carbon-based composite material C.
[0079] (2) By using the CVD method, with methane gas as the carbon source, the methane partial pressure is 10 kPa, the argon partial pressure is 85 kPa, the hydrogen partial pressure is 5 kPa, and a deposition reaction is carried out on the surface of the carbon-based composite material C obtained in step (1) at 1100 °C for 1.5 h to coat a carbon coating layer on the surface of the carbon-based composite material C obtained in step (1), obtaining carbon-based composite material D; based on the total mass of the carbon-based composite material D obtained in this step being 100%, the mass fraction of the carbon coating layer is 2.5%.
[0080] Application of Comparative Example 1
[0081] The preparation method of the lithium-ion battery in this application example is the same as that of Application Example 1, except that the carbon-based composite material D obtained in step (2) of Comparative Example 1 is used.
[0082] Comparative Example 2
[0083] A preparation method of a carbon-based composite material for a secondary battery negative electrode includes the following steps:
[0084] (1) 30 g of a reticular metal-organic framework material (IRMOF-9) with Zn as the central atom (manufacturer: CHEMSOON, brand CAS No.: 473981-45-2) and 2 g of nano-silicon are mixed, and calcined in an argon atmosphere at 1200 °C for 4 h to obtain carbon-based composite material E.
[0085] (2) By using the CVD method, methane gas is used as the carbon source, the partial pressure of methane is 10 kPa, the partial pressure of argon is 85 kPa, and the partial pressure of hydrogen is 5 kPa. A deposition reaction is carried out on the surface of the carbon-based composite material E obtained in step (1) at 1100 °C, and the temperature is kept constant for 1.5 h to coat a carbon coating layer on the surface of the carbon-based composite material E obtained in step (1), thereby obtaining a carbon-based composite material F; based on the total mass of the carbon-based composite material F obtained in this step being 100%, the mass fraction of the carbon coating layer is 2.5%.
[0086] Applied Comparative Example 2
[0087] The preparation method of the lithium-ion battery in this applied example is the same as that in Applied Example 1, except that the carbon-based composite material F obtained in step (2) of Comparative Example 2 is used.
[0088] Electrochemical performance test: The lithium-ion batteries of Applied Examples 1-5 and Applied Comparative Examples 1-2 are subjected to charge-discharge performance tests in a constant-temperature biochemical incubator at 30 °C. The equipment used for the constant-current method charge-discharge performance test is the Neware battery test system produced by Shenzhen Neware Electronic Co., Ltd., with the model CT-4000. By adjusting the preset cycle steps and inputting parameters such as a current density of 0.33 C and a charge-discharge voltage of 0.005-1.5 V, the test can be carried out. After the test, the charge-discharge performance of the electrode active material is judged by the capacity retention rate.
[0089] From Figure 1 It can be seen that after 200 cycles, the capacity retention rate of the lithium-ion battery in Applied Example 1 is 94%; the capacity retention rate of the lithium-ion battery in Applied Example 2 is 88.3%; while the capacity retention rate of the lithium-ion battery in Comparative Example 1 is only 80%. The reason is that in Examples 1-2, the porous carbon matrix is combined with the high-expansion negative electrode active material, and the obtained carbon-based composite material has a porous structure, which can relieve the structural rupture at the particle level caused by the volume expansion of the high-expansion negative electrode active material and improve the cycle performance of the electrode material; while in Comparative Example 1, carbon black (SP) is combined with the high-expansion negative electrode active material, and the above effects are not achieved.
[0090] In addition, after 200 cycles, the capacity retention rate of the lithium-ion battery in Applied Example 1 is also higher than that in Applied Comparative Example 2.
[0091] In the present invention, terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.
[0092] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for preparing a carbon-based composite material for the negative electrode of a secondary battery, characterized in that, It includes the following steps: (1) Pyrolyze the metal-organic framework material to obtain a porous carbon matrix; (2) Compound the porous carbon matrix with a high-expansion negative electrode active material to obtain the carbon-based composite material.
2. The preparation method of the carbon-based composite material for the negative electrode of a secondary battery according to claim 1, characterized in that, In step (1), the metal-organic framework material is selected from at least one of reticular metal-organic framework materials, zeolitic imidazolate framework materials, and Levasil framework materials, preferably a reticular metal-organic framework material; and / or, the central atom of the metal-organic framework material is selected from at least one of Zn, Cu, Fe, Co, Ni, Mg, and La, preferably at least one of Zn, Mg, Cu, and Fe.
3. The preparation method of the carbon-based composite material for the negative electrode of the secondary battery according to claim 1, wherein In step (1), the pyrolysis treatment is carried out in a vacuum or a protective atmosphere; and / or, the temperature of the pyrolysis treatment is 750-1500 °C, preferably 900-1400 °C; and / or, the time of the pyrolysis treatment is 1-8 h, preferably 2-6 h.
4. The preparation method of the carbon-based composite material for the negative electrode of the secondary battery according to claim 1, characterized in that In step (1), the specific surface area of the porous carbon matrix is 500 - 3000 m 2 / g, preferably 1500 - 2000 m 2 / g; and / or, the pore volume of the porous carbon matrix is 0.7 - 1.2 cm 3 / g, preferably 0.8 - 0.9 cm 3 / g; the pore diameter of the porous carbon matrix is 2 - 1000 nm, preferably 2 - 200 nm; and / or, the surface fractal dimension of the porous carbon matrix is 2 - 3, preferably 2.2 - 2.
7.
5. The preparation method of the carbon-based composite material for the negative electrode of a secondary battery according to claim 1, wherein In step (1), after the pyrolysis treatment, pickling treatment is also carried out to obtain a porous carbon matrix.
6. The preparation method of the carbon-based composite material for the negative electrode of a secondary battery according to claim 1, characterized in that, In step (2), the high-expansion negative electrode active material is selected from at least one of elemental Si, P, Ge, SiO x (0 < x ≤ 2), PO y (0 < y ≤ 2.5), GeO z (0 < z ≤ 2), and SnO u (0 < u ≤ 2), preferably Si; and / or, the composite is carried out by CVD method, fluidized bed method, sol-gel method or hydrothermal method, preferably CVD method or fluidized bed method.
7. The preparation method of the carbon-based composite material for the negative electrode of a secondary battery according to claim 1, characterized in that, In step (2), the mass ratio of the porous carbon matrix to the high-expansion negative electrode active material is 1:4-5:
1.
8. The preparation method of the carbon-based composite material for the negative electrode of a secondary battery according to claim 1, characterized in that, It further includes step (3) After the compounding, carbon coating and / or conductive polymer coating are carried out to obtain the carbon-based composite material.
9. The method for preparing the carbon-based composite material for the negative electrode of a secondary battery according to claim 1, wherein In step (3), the carbon source used for the carbon coating is selected from at least one of asphalt, resin, glucose, methane, and acetylene; and / or, the conductive polymer includes at least one of polydopamine, polyaniline, and polyvinylpyrrolidone.
10. A carbon-based composite material for the negative electrode of a secondary battery, characterized in that, Prepared by the preparation method according to any one of claims 1-9.