Porous carbon composite material and preparation method thereof

Abstract

The invention relates to the technical field of porous carbon material preparation, in particular to a porous carbon composite material and a preparation method thereof. The preparation method comprises the following steps: performing first mixing on an organic carbon source and hollow carbon spheres to obtain a first precursor; the organic carbon source comprises a first organic carbon source containing a first active group; performing second mixing on the first precursor, an organic binder, a carbon nanotube and a cross-linking agent to obtain a second precursor; the carbon nanotube contains a second active group, and both the first active group and the second active group can react with the cross-linking agent; performing cross-linking curing on the second precursor to obtain a composite precursor; and carrying out carbonization treatment and activation treatment on the composite precursor to prepare the porous carbon composite material. According to the preparation method, the hollow carbon spheres are added in the preparation of the first precursor, closed pores formed by the hollow carbon spheres can reduce the expansion of the porous carbon composite material, and the spherical structure of the porous carbon spheres can also improve the pressure resistance of the porous carbon composite material.

Description

Technical Field

[0001] The present application relates to the technical field of porous carbon material preparation, and in particular to a porous carbon composite material and a preparation method thereof. Background Art

[0002] Silicon-carbon anode material is a new type of negative electrode material for high-energy-density lithium-ion batteries. Porous carbon is a key component of this material. Porous carbon is primarily prepared by carbonizing and activating a carbon source to create pores. The pore volume and specific surface area of ​​the porous carbon are typically controlled by adjusting the amount of activator and the temperature. However, conventional porous carbon suffers from significant expansion and poor electronic conductivity during application. Summary of the Invention

[0003] Based on this, in order to reduce the expansion of porous carbon materials and improve the electronic conductivity of porous carbon materials, the present application provides a porous carbon composite material and a preparation method thereof.

[0004] In a first aspect of the present application, a method for preparing a porous carbon composite material is provided, the method comprising the following steps:

[0005] The organic carbon source and the hollow carbon sphere are first mixed to obtain a first precursor; the organic carbon source includes a first organic carbon source containing a first active group;

[0006] The first precursor, the organic binder, the carbon nanotubes and the crosslinking agent are mixed for a second time to obtain a second precursor; the carbon nanotubes contain second active groups, and both the first active groups and the second active groups can react with the crosslinking agent;

[0007] Cross-linking and curing the second precursor to obtain a composite precursor;

[0008] The composite precursor is subjected to carbonization treatment and activation treatment to prepare the porous carbon composite material.

[0009] In some embodiments, the first reactive group includes one or more of a carboxyl group and a carbonyl group; and / or,

[0010] The second reactive group includes one or more of a carboxyl group and a carbonyl group; and / or,

[0011] The cross-linking agent includes one or more of polycarboxylic acids and anhydrides of polycarboxylic acids.

[0012] In some embodiments, the first organic carbon source comprises an acid-based resin; and / or,

[0013] The organic carbon source further comprises coal tar; and / or,

[0014] The diameter of the hollow carbon sphere is 50nm~500nm, and the specific surface area is 100m 2 / g~500m 2 / g.

[0015] In some embodiments, the mass ratio of the coal tar, the hollow carbon spheres and the acid-based resin is 20-40:5-15:30; and / or,

[0016] The acid-based resin includes at least one of acrylic resin, alkyd resin and fumaric resin.

[0017] In some embodiments, the mass ratio of the first precursor, the organic binder, the carbon nanotubes, and the cross-linking agent is 100:2-8:1-5:1-5; and / or,

[0018] The organic binder includes one or more of oxidized asphalt and oxidized resin; and / or,

[0019] The cross-linking agent includes one or more of terephthalic acid, phthalic acid, isophthalic acid, gallic acid, trimesic acid, perylenetetracarboxylic dianhydride and pyromellitic anhydride; and / or,

[0020] The carbon nanotubes include carboxylated carbon nanotubes.

[0021] In some embodiments, the second mixing conditions include: a temperature of 300° C. to 450° C., and a time of 0.5 h to 2 h; and / or,

[0022] The curing and cross-linking conditions include: a temperature of 500° C. to 650° C. and a time of 1 hour to 3 hours.

[0023] In some embodiments, the carbonization treatment conditions include: a temperature of 700° C. to 900° C. and a time of 1 h to 3 h; and / or,

[0024] The activation treatment conditions include: the activating agent includes one or more of carbon dioxide and water vapor, the temperature is 950° C. to 1100° C., the time is 1 hour to 6 hours, and the activating agent flow rate is 100 SCCM to 500 SCCM.

[0025] In a second aspect of the present application, a porous carbon composite material is provided, which is prepared by the preparation method described above.

[0026] In some embodiments, the porous carbon composite material satisfies one or more of the following conditions:

[0027] (1) The pore size of the porous carbon composite material is 2 nm to 10 nm;

[0028] (2) The pore volume of the porous carbon composite material is 0.7 cm3 / g~1.0cm 3 / g;

[0029] (3) The specific surface area of ​​the porous carbon composite material is 1800 m 2 / g~2200m 2 / g;

[0030] (4) The tap density of the porous carbon composite material is 0.3 g / cm 3 ~0.8g / cm 3 .

[0031] This application has the following beneficial effects:

[0032] The preparation method described in the present application adds hollow carbon spheres to the preparation of the first precursor. The closed pores formed by the hollow carbon spheres can reduce the expansion of the porous carbon composite material, and the spherical structure of the porous carbon spheres can also improve the compressive resistance of the porous carbon composite material. At the same time, a cross-linking agent is added to the preparation of the second precursor. The first active group contained in the first organic carbon source and the second active group contained in the carbon nanotubes can both chemically react with the cross-linking agent. Through the chemical reaction, the porous carbon and carbon nanotubes in the prepared porous carbon composite material can form a stable three-dimensional network structure, further reducing the expansion of the porous carbon composite material and improving its electronic conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1 Flowchart of a method for preparing a composite porous carbon material according to some embodiments.

[0035] Figure 2 This is a scanning electron microscope test result of the porous carbon composite material prepared in Example 1. DETAILED DESCRIPTION

[0036] To facilitate understanding of the present application, the present application will be described more fully below in conjunction with the specific embodiments. Preferred embodiments of the present application are provided in the specific embodiments. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] Unless otherwise specified or incompatible therewith, terms and phrases used in this application shall have the following meanings:

[0039] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of the features.

[0040] In this application, the percentage concentration involved, unless otherwise specified, refers to the final concentration. The final concentration refers to the percentage of the added component in the system after the addition of the component.

[0041] In this application, the terms "further," "further," "particularly," "for example," "such as," "example," and "for example" are used for descriptive purposes to indicate that the preceding and following technical solutions are related in terms of their coverage, but should not be construed as limiting the preceding technical solution or the scope of protection of this document. In this document, unless otherwise specified, "A (such as B)" means that B is a non-limiting example of A, and it is understood that A is not limited to B.

[0042] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed in this application should be understood to include any and all subranges subsumed therein.

[0043] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0044] The terms "including," "having," and any variations thereof in the embodiments of the present application are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not limited to the listed steps or units but may optionally include steps or units not listed, or may optionally include other steps or components inherent to the process, method, product, or apparatus.

[0045] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0046] In the flowchart of the present application, although the various steps are displayed in sequence as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified in the text, there is no strict order restriction for the execution of these steps, and they can be performed in other orders. Moreover, at least part of the steps in the figure may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily performed at the same time, but can be performed at different times. Their execution order is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of other sub-steps or stages.

[0047] Porous carbon materials are a key component of silicon-carbon anode materials. Traditionally, porous carbon is made by carbonizing a carbon source and then adding an activator to create pores. The pore volume and specific surface area of ​​the porous carbon are controlled by adjusting the activator dosage and temperature. However, due to its open pores, porous carbon still suffers from significant expansion and poor electronic conductivity during application.

[0048] Based on this, a first aspect of the present application provides a method for preparing a porous carbon composite material, the preparation method comprising the following steps S1 to S4.

[0049] S1: An organic carbon source and hollow carbon spheres are first mixed to obtain a first precursor. The organic carbon source includes a first organic carbon source containing a first active group.

[0050] S2: The first precursor, the organic binder, the carbon nanotubes, and the crosslinking agent are mixed for a second time to obtain a second precursor, wherein the carbon nanotubes contain second active groups, and both the first active groups and the second active groups are capable of reacting with the crosslinking agent.

[0051] S3: cross-linking and curing the second precursor to obtain a composite precursor.

[0052] S4: performing carbonization treatment and activation treatment on the composite precursor to prepare a porous carbon composite material.

[0053] The above preparation method adds hollow carbon spheres in the preparation of the first precursor. The closed pores formed by the hollow carbon spheres can reduce the expansion of the porous carbon composite material, and the spherical structure of the porous carbon spheres can also improve the compressive resistance of the porous carbon composite material; at the same time, a cross-linking agent is added in the preparation of the second precursor. The first active group contained in the first organic carbon source and the second active group contained in the carbon nanotubes can both react chemically with the cross-linking agent. Through the chemical reaction, the porous carbon and carbon nanotubes in the porous carbon composite material can form a stable three-dimensional network structure, further reducing the expansion of the porous carbon composite material and improving its electronic conductivity.

[0054] In some embodiments, the first reactive group includes one or more of a carboxyl group and a carbonyl group.

[0055] In some embodiments, the first organic carbon source comprises an acid-based resin. It is understood that an acid-based resin refers to a resin containing a carboxyl group.

[0056] In some embodiments, the acid-based resin includes one or more of an acrylic resin, an alkyd resin, and a fumaric resin.

[0057] In some embodiments, the organic carbon source further comprises a second organic carbon source comprising coal tar.

[0058] It can be understood that by using coal tar and acid-based resin as carbon sources at the same time, the porous carbon composite material can have a pore size distribution with different pore sizes after carbonization treatment, further reducing the expansion of the porous carbon composite material.

[0059] In some embodiments, the mass ratio of coal tar, hollow carbon spheres and acid-based resin is 20-40:5-15:30. For example, the mass ratio of coal tar to acid-based resin can be 20:30, 25:30, 30:30, 35:30 or 40:30, and the mass ratio of hollow carbon spheres to acid-based resin can be 5:30, 6:30, 7:30, 8:30, 9:30, 10:30, 11:30, 12:30, 13:30, 14:30 or 15:30.

[0060] As can be understood, hollow carbon spheres refer to carbon-based materials with a hollow structure, with an outer shell composed of a carbon material (such as graphitized carbon, amorphous carbon, or carbon doped with other elements) and a hollow interior. These hollow carbon spheres are commercially available, for example, from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., catalog number 103569; CAS number 7440-44-0.

[0061] In some embodiments, the diameter of the hollow carbon sphere can be 50 nm to 500 nm, and the specific surface area can be 100 m 2 / g~500m 2 / g. For example, the diameter of the hollow carbon sphere can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm, and in some examples, it can be within the range formed by any two of these point values ​​as end values. For example, the specific surface area of ​​the hollow carbon sphere can be 100m 2 / g, 150m 2 / g, 200m 2 / g, 250m 2 / g、300m 2 / g、350m 2 / g, 400m 2 / g, 450m 2 / g or 500m 2 / g, and in some examples, may be within a range consisting of any two of these point values ​​as end values.

[0062] In some embodiments, the organic carbon source and the hollow carbon spheres are first mixed to obtain a first precursor, comprising:

[0063] Coal tar is mixed with an organic solvent, hollow carbon spheres and acid-based resin are added, and then spray-dried to obtain a first precursor.

[0064] It can be understood that the organic solvent may be an organic solvent commonly used in the art, and by way of non-limiting example, the organic solvent may be ethanol.

[0065] It is understandable that there is no special requirement for the spray drying conditions, and the spray drying can be carried out according to conventional conditions in the art.

[0066] In some embodiments, the particle size of the first precursor is 5 μm to 10 μm.

[0067] In some embodiments, the mass ratio of the first precursor, the organic binder, the carbon nanotubes, and the crosslinking agent is 100:2-8:1-5:1-5. For example, the mass ratio of the first precursor to the organic binder can be 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, or 100:8; the mass ratio of the first precursor to the carbon nanotubes can be 100:1, 100:2, 100:3, 100:4, or 100:5; and the mass ratio of the first precursor to the crosslinking agent can be 100:1, 100:2, 100:3, 100:4, or 100:5.

[0068] In some embodiments, the organic binder includes one or more of oxidized asphalt and oxidized resin.

[0069] In some specific examples, the organic binder is oxidized asphalt, which becomes liquid under heating conditions. The hydroxyl / carboxyl groups it contains give it good bonding ability with the acid-based resin, and can bond the first precursor and the carbon nanotubes to form a second precursor. At the same time, the oxidized asphalt can also form amorphous carbon together with the organic carbon source during the carbonization process.

[0070] In some embodiments, the cross-linking agent includes one or more of a polycarboxylic acid and an anhydride of a polycarboxylic acid.

[0071] In some specific examples, the polycarboxylic acid includes at least one of terephthalic acid, phthalic acid, isophthalic acid, gallic acid, and trimesic acid.

[0072] In some specific examples, the anhydride of the polycarboxylic acid includes at least one of perylenetetracarboxylic dianhydride and pyromellitic anhydride.

[0073] In some embodiments, the second reactive group includes one or more of a carboxyl group and a carbonyl group.

[0074] In some embodiments, the carbon nanotubes include carboxylated carbon nanotubes.

[0075] It is understood that carboxylated carbon nanotubes are carbon nanotubes containing carboxyl groups on their surfaces, and can be obtained by conventional methods in the art, for example, by surface treatment with a strong acidic oxidant such as nitric acid or sulfuric acid.

[0076] In some embodiments, the second mixing conditions include: a temperature of 300° C. to 450° C. and a time of 0.5 h to 2 h. For example, the second mixing temperature may be 300° C., 350° C., 400° C., or 450° C., and the second mixing time may be 0.5 h, 1 h, 1.5 h, or 2 h.

[0077] In some embodiments, the second mixing may be performed in a rotary kiln.

[0078] In some embodiments, the particle size of the second precursor is 6 μm to 12 μm.

[0079] In some embodiments, the curing and crosslinking conditions include: a temperature of 500° C. to 650° C. and a time of 1 hour to 3 hours. For example, the curing and crosslinking temperature may be 500° C., 550° C., 600° C., or 650° C., and the curing and crosslinking time may be 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours.

[0080] It can be understood that in some embodiments, in step S3, under the above-mentioned curing and crosslinking conditions, the crosslinking agent is prone to generate oxygen free radicals, which can chemically react with the groups contained in the acid-based resin and the carboxylated carbon nanotubes to form a carbon-oxygen-carbon structure, thereby achieving curing and crosslinking.

[0081] In some embodiments, the carbonization treatment conditions include: a temperature of 700° C. to 900° C. and a time of 1 hour to 3 hours. For example, the carbonization treatment temperature may be 700° C., 750° C., 800° C., 850° C., or 900° C., and the crosslinking and curing time may be 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours.

[0082] It can be understood that through the above carbonization treatment, the organic carbon source in the composite precursor can form amorphous carbon.

[0083] In some embodiments, the activation treatment conditions include: the activating agent includes one or more of carbon dioxide and water vapor, the temperature is 950° C. to 1100° C., the time is 1 hour to 6 hours, and the activating agent flow rate is 100 SCCM to 500 SCCM. For example, the activation treatment temperature can be 950° C., 1000° C., 1050° C., or 1100° C., the activation treatment time can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours, and the activating agent flow rate can be 100 SCCM, 200 SCCM, 300 SCCM, 400 SCCM, or 500 SCCM.

[0084] It can be understood that during the above activation treatment, an activating agent is introduced into the material obtained by carbonization treatment, and porous carbon can be obtained through activation and pore formation by the activating agent.

[0085] In a second aspect of the present application, a porous carbon composite material is provided, which is prepared by the preparation method described above.

[0086] In some embodiments, the porous carbon composite material prepared by the above method includes a carbon substrate and carbon nanotubes, the carbon substrate includes porous carbon and hollow carbon spheres, and the carbon substrate and the carbon nanotubes form a three-dimensional network structure.

[0087] In some embodiments, the porous carbon composite material has a pore size of 2 nm to 10 nm.

[0088] In some embodiments, the porous carbon composite material has a pore volume of 0.7 cm 3 / g~1.0cm 3 / g.

[0089] In some specific examples, the pore volume of the porous carbon composite material is 0.8 cm 3 / g~1.0cm 3 / g.

[0090] In some embodiments, the porous carbon composite material has a specific surface area of ​​1800 m 2 / g~2200m 2 / g.

[0091] In some embodiments, the porous carbon composite material has a tap density of 0.3 g / cm 3 ~0.8g / cm 3 .

[0092] It can be understood that the porous carbon negative electrode material provided in the present application has low expansion and high ionic conductivity. It can be used as a component of the negative electrode active material layer in the negative electrode sheet, or it can be compounded with silicon material to form a silicon-carbon material and then used in the negative electrode sheet.

[0093] In order to make the purpose and advantages of the present application clearer, the preparation method of the porous carbon composite material of the present application and its effects are further described in detail below with reference to specific examples. It should be understood that the specific examples described herein are only used to explain the present application and shall not be used to limit the present application. The following examples do not include other components except unavoidable impurities unless otherwise specified. The drugs and instruments used in the examples are conventionally selected in the art unless otherwise specified. The experimental methods for which specific conditions are not specified in the examples are implemented according to conventional conditions, such as the conditions described in the literature, books, or methods recommended by the manufacturer.

[0094] Example 1

[0095] A method for preparing a porous carbon composite material comprises the following steps:

[0096] S1: 300g coal tar was dissolved in 5000g ethanol organic solvent, and 100g hollow carbon balls (diameter of 200nm~400nm, specific surface area of ​​314m 2 / g) and 300g acrylic resin (CAS:9003-01-4) were uniformly dispersed and spray-dried to obtain a first precursor with a particle size of about 7µm;

[0097] S2: 100 g of the first precursor, 5 g of oxidized pitch, 3 g of carboxylated carbon nanotubes, and 3 g of terephthalic acid crosslinker were mixed at 400 °C for 1 h to obtain a second precursor with a particle size of approximately 8 µm.

[0098] S3: cross-linking and curing the second precursor at 600° C. for 2 h to obtain a composite precursor;

[0099] S4: The composite precursor was carbonized at 800° C. for 2 h, and then carbon dioxide gas was introduced and activated at a temperature of 1000° C. and a carbon dioxide flow rate of 300 SCCM for 3 h to obtain a porous carbon composite material.

[0100] Example 2

[0101] S1: Dissolve 200g coal tar in 5000g ethanol organic solvent, and add 50g hollow carbon balls (diameter 50nm~80nm, specific surface area 498m 2 / g) and 300g of alkyd resin (CAS: 63148-69-6) were uniformly dispersed and spray-dried to obtain a first precursor with a particle size of about 5µm;

[0102] S2: 100 g of the first precursor, 2 g of oxidized pitch, 1 g of carboxylated carbon nanotubes and 1 g of phthalic acid were mixed at 300 °C for 2 h to obtain a second precursor with a particle size of 6 µm.

[0103] S3: cross-linking and curing the second precursor at 500° C. for 3 h to obtain a composite precursor;

[0104] S4: The composite precursor was carbonized at 700° C. for 3 h, and then water vapor was introduced and activated at a temperature of 950° C. and a carbon dioxide flow rate of 100 SCCM for 6 h to obtain a porous carbon composite material.

[0105] Example 3

[0106] S1: Dissolve 400g coal tar in 5000g ethanol organic solvent and add 150g hollow carbon spheres (diameter 200nm~400nm, specific surface area 293m 2 / g) and 300g of fumaric acid resin were evenly dispersed and spray-dried to obtain a first precursor with a particle size of about 10µm;

[0107] S2: 100 g of the first precursor, 8 g of oxidized asphalt, 5 g of carboxylated carbon nanotubes, and 5 g of isophthalic acid crosslinker were mixed at 450 °C for 0.5 h to obtain a second precursor with a particle size of approximately 12 µm;

[0108] S3: cross-linking and curing the second precursor at 650° C. for 1 h to obtain a composite precursor;

[0109] S4: The composite precursor was carbonized at 900° C. for 1 h, and then carbon dioxide gas was introduced and activated at a temperature of 1100° C. and a carbon dioxide flow rate of 500 SCCM for 1 h to obtain a porous carbon composite material.

[0110] Example 4

[0111] The method is basically the same as Example 1, except that the diameter of the hollow carbon sphere is adjusted to 50-80 nm.

[0112] Example 5

[0113] The method is basically the same as Example 1, except that the ratio of coal tar to acrylic resin is adjusted to 5:30.

[0114] Example 6

[0115] The method is basically the same as Example 1, except that the ratio of the first precursor to the carboxylated carbon nanotubes is adjusted to 100:10.

[0116] Comparative Example 1

[0117] The process is basically the same as Example 1, except that in step S1, hollow carbon spheres are not added.

[0118] Comparative Example 2

[0119] The process is basically the same as Example 1, except that terephthalic acid is not added in step S2.

[0120] Comparative Example 3

[0121] The process is basically the same as Example 1, except that in step S2, no carboxylated carbon nanotubes are added.

[0122] Comparative Example 4

[0123] The method is basically the same as Example 1, except that, in step S2, ordinary carbon nanotubes of the same weight are used to replace the carboxylated carbon nanotubes.

[0124] Test Example 1

[0125] The porous carbon composite material prepared in Example 1 was tested by scanning electron microscopy (SEM). Figure 2 shown.

[0126] Depend on Figure 2 It can be seen from the figure that the material presents a secondary granular structure with slight adhesion, uniform size distribution, and particle size ranging from 5μm to 10μm.

[0127] Test Example 2

[0128] 1. Physical and chemical performance test:

[0129] The pore volume and pore diameter of the materials obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were tested with reference to the national standard GB / T-38949-2020 "Standard particle method for determination of pore size of porous membranes" and GB / T7702.20-2008 "Pore volume detection of coal-based activated carbon"; and the particle size D50, specific surface area and tap density were tested in accordance with the national standard GB / T38823-2020 "Silicon Carbon".

[0130] The powder electrical conductivity of the materials obtained in Examples 1 to 6 and Comparative Examples 1 to 4 was tested using a four-probe tester.

[0131] The test results are shown in Table 1.

[0132] 2. Stress resistance test:

[0133] The compressive resistance of the materials obtained in Examples 1-6 and Comparative Examples 1-4 was tested using the pressure-specific surface area method. This method measures the compressive resistance of the materials by applying a certain pressure to the material's specific surface area. In a powder pressure testing device, the material is placed in a mold, a certain pressure is applied, and then the specific surface area of ​​the material is removed for testing. Different specific surface areas are obtained using different pressures.

[0134] The test results are shown in Table 2 below.

[0135] 3. Electrochemical performance test:

[0136] The porous carbon composite materials obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were used as negative electrode materials for lithium-ion batteries to prepare button batteries according to the following method:

[0137] A porous carbon composite material, a binder, a conductive agent and a solvent are mixed, stirred to form a slurry, coated on a copper foil, and dried and rolled to obtain a negative electrode sheet; the binder used is LA132, the conductive agent is SP (conductive carbon black), and the solvent is NMP. The amount ratio of the porous carbon composite material, SP, LA132 and NMP is 70:15g:15g:300mL; the electrolyte is a solution with LiPF6 as the electrolyte with a concentration of 1 mol / L, wherein the solvent is a mixture of EC and DEC with a volume ratio of 1:1; the metal lithium sheet is the counter electrode, and the diaphragm is a polypropylene (PP) film.

[0138] Each button cell was assembled in an argon-filled glove box and then subjected to the following performance tests:

[0139] The electrochemical performance was carried out on a Wuhan Blue Electric CT2001A battery tester with a charge and discharge voltage range of 0.005V to 2.0V and a charge and discharge rate of 0.1C. The discharge specific capacity and initial efficiency of the corresponding button battery were tested. At the same time, the cycle performance of the corresponding button battery was tested (0.1C / 0.1C, 100 cycles).

[0140] Full charge expansion test: the thickness of the electrode after rolling is D1, and the thickness of the electrode after full charge to 100% SOC is D2. The full charge expansion = (D2-D1) / D1;

[0141] The lithium ion diffusion coefficient was tested by GITT.

[0142] The test results are shown in Table 3.

[0143] Table 1

[0144]

[0145] Table 2

[0146]

[0147] Table 3

[0148]

[0149] From Tables 1-3, it can be seen that, compared with the comparative example, the composite material prepared in the embodiment has a larger specific surface area and a lower powder resistivity. The button test cells assembled using the composite material prepared in the embodiment have a higher discharge specific capacity, first efficiency, cycle performance and diffusion coefficient, and have a lower full-charge expansion, and have better overall performance.

[0150] Compared with the comparative example, the composite material prepared in the example has a smaller increase in specific surface area after being subjected to step pressure, indicating that the composite material prepared in the example has a stronger compressive resistance.

[0151] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0152] The embodiments described above only express several implementation methods of the present application, which are convenient for understanding the technical solutions of the present application in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a porous carbon composite material, characterized in that: The preparation method comprises the following steps: The organic carbon source and the hollow carbon sphere are first mixed to obtain a first precursor; the organic carbon source includes a first organic carbon source containing a first active group; The first precursor, the organic binder, the carbon nanotubes and the cross-linking agent are mixed in a second process to obtain a second precursor; The carbon nanotubes contain a second active group, and both the first active group and the second active group are capable of reacting with the cross-linking agent; Cross-linking and curing the second precursor to obtain a composite precursor; The composite precursor is subjected to carbonization treatment and activation treatment to prepare the porous carbon composite material.

2. The preparation method according to claim 1, characterized in that The first reactive group includes one or more of a carboxyl group and a carbonyl group; and / or, The second reactive group includes one or more of a carboxyl group and a carbonyl group; and / or, The cross-linking agent includes one or more of polycarboxylic acids and anhydrides of polycarboxylic acids.

3. The preparation method according to claim 1, characterized in that The first organic carbon source includes an acid-based resin; And / or, the organic carbon source further includes a second organic carbon source, and the second organic carbon source includes coal tar.

4. The preparation method according to any one of claims 1 to 3, characterized in that The diameter of the hollow carbon sphere is 50nm~500nm, and the specific surface area is 100m 2 / g~500m 2 / g.

5. The preparation method according to any one of claims 1 to 3, characterized in that The mass ratio of the coal tar, the hollow carbon spheres and the acid-based resin is 20-40:5-15:30; and / or, The acid-based resin includes one or more of acrylic resin, alkyd resin and fumaric resin.

6. The preparation method according to any one of claims 1 to 3, characterized in that The mass ratio of the first precursor, the organic binder, the carbon nanotubes and the cross-linking agent is 100:2-8:1-5:1-5; and / or, The organic binder includes oxidized asphalt and oxidized resin; and / or, The cross-linking agent includes one or more of terephthalic acid, phthalic acid, isophthalic acid, gallic acid, trimesic acid, perylenetetracarboxylic dianhydride and pyromellitic anhydride; and / or, The carbon nanotubes include carboxylated carbon nanotubes.

7. The preparation method according to any one of claims 1 to 3, characterized in that The second mixing conditions include: temperature of 300° C. to 450° C., time of 0.5 h to 2 h; and / or, The curing and cross-linking conditions include: a temperature of 500° C. to 650° C. and a time of 1 hour to 3 hours.

8. The preparation method according to any one of claims 1 to 3, characterized in that The carbonization treatment conditions include: a temperature of 700° C. to 900° C. and a time of 1 h to 3 h; and / or, The activation treatment conditions include: the activating agent includes one or more of carbon dioxide and water vapor, the temperature is 950° C. to 1100° C., the time is 1 hour to 6 hours, and the activating agent flow rate is 100 SCCM to 500 SCCM.

9. A porous carbon composite material, characterized in that The method is as described in any one of claims 1 to 8.

10. The porous carbon composite material according to claim 9, characterized in that Meet one or more of the following conditions; (1) The pore size of the porous carbon composite material is 2 nm to 10 nm; (2) The pore volume of the porous carbon composite material is 0.7 cm 3 / g~1.0cm 3 / g; (3) The specific surface area of ​​the porous carbon composite material is 1800 m 2 / g~2200m 2 / g; (4) The tap density of the porous carbon composite material is 0.3 g / cm 3 ~0.8g / cm 3 .

Images