Porous carbon composite and method for producing the same

Abstract

The application 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: mixing 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; mixing the first precursor, an organic binder, carbon nanotubes and a crosslinking agent to obtain a second precursor; the carbon nanotubes contain a second active group; the first active group and the second active group can react with the crosslinking agent; crosslinking and curing the second precursor to obtain a composite precursor; and performing carbonization treatment and activation treatment on the composite precursor to prepare the porous carbon composite material. In the preparation of the first precursor, the hollow carbon spheres are added, 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 compression resistance of the porous carbon composite material.

Description

Technical Field

[0001] This application relates to the field of porous carbon material preparation technology, and in particular to a porous carbon composite material and its preparation method. Background Technology

[0002] Silicon-carbon anode material is a novel anode material used in high-energy-density lithium-ion batteries. Porous carbon is one of the key components in silicon-carbon anode materials. Porous carbon is mainly prepared by carbonizing and activating a carbon source to create pores. The pore volume and specific surface area of ​​the porous carbon are usually controlled by adjusting the amount of activator and the temperature. Traditional porous carbon suffers from problems such as large 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 their electronic conductivity, this application provides a porous carbon composite material and its preparation method.

[0004] A first aspect of this application provides a method for preparing a porous carbon composite material, the method comprising the following steps:

[0005] An organic carbon source and hollow carbon spheres are mixed in a first process to obtain a first precursor; the organic carbon source includes a first organic carbon source containing a first active group.

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

[0007] The second precursor is cross-linked and cured to obtain a composite precursor;

[0008] The porous carbon composite material is prepared by carbonizing and activating the composite precursor.

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

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

[0011] The crosslinking 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 also includes coal tar; and / or,

[0014] The hollow carbon spheres have a diameter of 50nm~500nm and a specific surface area of ​​100m². 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 crosslinking agent is 100:2-8:1-5:1-5; and / or,

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

[0019] The crosslinking agent includes one or more of terephthalic acid, phthalic acid, isophthalic acid, gallic acid, pyromellitic acid, perylene dianhydride, and pyromellitic anhydride; and / or,

[0020] The carbon nanotubes include carboxylated carbon nanotubes.

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

[0022] The conditions for curing and crosslinking include: a temperature of 500℃ to 650℃ and a time of 1h to 3h.

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

[0024] The activation treatment conditions include: the activator includes one or more of carbon dioxide and water vapor, the temperature is 950℃~1100℃, the time is 1h~6h, and the activator flow rate is 100SCCM~500SCCM.

[0025] A second aspect of this application provides a porous carbon composite material 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 cm³.3 / g~1.0cm 3 / g;

[0029] (3) The specific surface area of ​​the porous carbon composite material is 1800 m². 2 / g~2200m 2 / g;

[0030] (4) The tap density of the porous carbon composite material is 0.3 g / cm³. 3 ~0.8g / cm 3 .

[0031] This application has the following beneficial effects:

[0032] The preparation method described in this application involves adding hollow carbon spheres during 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 strength of the porous carbon composite material. At the same time, a crosslinking agent is added during 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 nanotube can both react chemically with the crosslinking 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. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a flowchart illustrating a method for preparing complex porous carbon materials according to some embodiments.

[0035] Figure 2 The image shows the scanning electron microscope (SEM) results of the porous carbon composite material prepared in Example 1. Detailed Implementation

[0036] To facilitate understanding of this application, a more comprehensive description of the application will be provided below in conjunction with specific embodiments. Preferred embodiments of the application are given in the specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the 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 stated or in case of conflict, the terms or 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 construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0040] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0041] In this application, terms such as "further," "even more," "particularly," "for example," "like," "example," and "exemplary" are used for descriptive purposes to indicate a connection in the coverage of different technical solutions presented earlier and later, but should not be construed as limiting the preceding technical solution or restricting the scope of protection herein. Unless otherwise specified herein, A (e.g., B) indicates that B is a non-limiting example of A, and it can be 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 the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0043] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0044] The terms "comprising" and "having," and any variations thereof, used in the embodiments of this application, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to such processes, methods, products, or devices.

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

[0046] In the flowchart of this application, although the steps are shown sequentially according to the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps. They can be executed in other orders. Moreover, at least some of the steps in the diagram may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. Their execution order is not necessarily sequential, but can be performed alternately or in turn with at least some of other steps or other sub-steps or stages.

[0047] Porous carbon materials are an important component in silicon-carbon anode materials. Traditional porous carbon is produced by carbonizing a carbon source and creating pores with an activator. The pore volume and specific surface area of ​​the porous carbon are controlled by adjusting the amount of activator and the temperature. However, because porous carbon consists of open pores, it still suffers from problems such as large expansion and poor electronic conductivity during application.

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

[0049] S1: An organic carbon source and hollow carbon spheres are mixed in a first process 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, organic binder, carbon nanotubes, and crosslinking agent are mixed in a second process to obtain a second precursor. The carbon nanotubes contain a second active group, and both the first and second active groups are capable of reacting with the crosslinking agent.

[0051] S3: The second precursor is cross-linked and cured to obtain a composite precursor.

[0052] S4: Carbonize and activate the composite precursor to prepare porous carbon composite materials.

[0053] The above preparation method incorporates 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 strength of the porous carbon composite material. At the same time, a crosslinking 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 nanotube can both react chemically with the crosslinking 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, which further reduces the expansion of the porous carbon composite material and improves its electronic conductivity.

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

[0055] In some embodiments, the first organic carbon source includes an acid-based resin. Understandably, an acid-based resin refers to a resin containing carboxyl groups.

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

[0057] In some embodiments, the organic carbon source also includes a second organic carbon source, which includes coal tar.

[0058] Understandably, by using both coal tar and acid-based resin as carbon sources, carbonization can produce porous carbon composite materials with different pore sizes, thereby further reducing the expansion of the porous carbon composite materials.

[0059] In some embodiments, the mass ratio of coal tar, hollow carbon spheres, and acid-based resin is 20-40:5-15:30. Exemplarily, 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. Their outer shell is made of carbon materials (such as graphitized carbon, amorphous carbon, or carbon doped with other elements), while the interior is hollow. These hollow carbon spheres can be obtained through commercial channels, for example, they can be purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., item number: 103569; CAS: 7440-44-0.

[0061] In some embodiments, the diameter of the hollow carbon spheres can be 50 nm to 500 nm, and the specific surface area can be 100 m². 2 / g~500m 2 / g. For example, the diameter of the hollow carbon spheres can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, or 500nm, and in some examples can be within a range consisting of any two of these point values ​​as endpoints. For example, the specific surface area of ​​the hollow carbon spheres can be 100m². 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, in some examples, can be a range consisting of any two of these point values ​​as endpoints.

[0062] In some embodiments, an organic carbon source and 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 the first precursor.

[0064] Understandably, the organic solvent may be any organic solvent commonly used in the art, and by way of non-limiting example, the organic solvent may be ethanol.

[0065] Understandably, there are no special requirements for spray drying conditions; they can be carried out under conditions conventional in the field.

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

[0067] In some embodiments, the mass ratio of the first precursor, organic binder, carbon nanotubes, and crosslinking agent is 100:2-8:1-5:1-5. Exemplarily, 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 bitumen and oxidized resin.

[0069] In some specific examples, the organic binder is oxidized bitumen, which becomes liquid under heating conditions. Its hydroxyl / carboxyl groups give it good binding ability with acid-based resins, enabling it to bond the first precursor and carbon nanotubes to form the second precursor. At the same time, oxidized bitumen can also form amorphous carbon together with organic carbon sources during the carbonization process.

[0070] In some embodiments, the crosslinking agent includes one or more of a polycarboxylic acid and anhydrides 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 pyromellitic acid.

[0072] In some specific examples, the anhydrides of polycarboxylic acids include at least one of perylenetetracarboxylic dianhydride and pyromellitic dianhydride.

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

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

[0075] Understandably, carboxylated carbon nanotubes are carbon nanotubes with carboxyl groups on their surface, and can be obtained using conventional methods in the art, such as surface treatment with strong acidic oxidizing agents such as nitric acid or sulfuric acid.

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

[0077] In some implementations, the second mixing can be carried out in a rotary kiln.

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

[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 can be 500°C, 550°C, 600°C, or 650°C, and the curing and crosslinking time can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours.

[0080] Understandably, in some embodiments, in step S3, under the above-mentioned curing and crosslinking conditions, the crosslinking agent readily generates oxygen free radicals, which can chemically react with the groups contained in the acid-based resin and 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 can be 700°C, 750°C, 800°C, 850°C, or 900°C, and the crosslinking and curing time can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours.

[0082] Understandably, 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 activator comprising one or more of carbon dioxide and water vapor, a temperature of 950°C to 1100°C, a time of 1 h to 6 h, and an activator flow rate of 100 SCCM to 500 SCCM. Exemplarily, the activation treatment temperature can be 950°C, 1000°C, 1050°C, or 1100°C; the activation treatment time can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, or 6 h; and the activator flow rate can be 100 SCCM, 200 SCCM, 300 SCCM, 400 SCCM, or 500 SCCM.

[0084] Understandably, in the above activation process, an activator is introduced into the material obtained by carbonization, and porous carbon can be obtained through activation and pore formation by the activator.

[0085] A second aspect of this application provides a porous carbon composite material 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 carbon nanotubes form a three-dimensional network structure.

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

[0088] In some embodiments, the pore volume of the porous carbon composite material is 0.7 cm³. 3 / g~1.0cm 3 / g.

[0089] In some specific examples, the pore volume of the porous carbon composite material is 0.8 cm³. 3 / g~1.0cm 3 / g.

[0090] In some embodiments, the specific surface area of ​​the porous carbon composite material is 1800 m². 2 / g~2200m 2 / g.

[0091] In some embodiments, the tap density of the porous carbon composite material is 0.3 g / cm³. 3 ~0.8g / cm 3 .

[0092] Understandably, the porous carbon anode material provided in this application has low expansion and high ionic conductivity. It can be used as a component of the anode active material layer in the anode sheet, or it can be combined with silicon material to form silicon-carbon material and then used in the anode sheet.

[0093] To make the objectives and advantages of this application clearer, the preparation method and effects of the porous carbon composite material of this application are further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining this application and should not be used to limit this application. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventional choices in the art. Experimental methods in the embodiments that do not specify specific conditions are implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0094] Example 1

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

[0096] S1: Dissolve 300g of coal tar in 5000g of ethanol organic solvent, and add 100g of hollow carbon spheres (diameter 200nm~400nm, specific surface area 314m²). 2 The first precursor (with a particle size of approximately 7µm) was uniformly dispersed with 300g of acrylic resin (CAS:9003-01-4) and spray-dried to obtain a first precursor with a particle size of approximately 7µm.

[0097] S2: Take 100g of the first precursor, 5g of oxidized asphalt, 3g of carboxylated carbon nanotubes and 3g of terephthalic acid crosslinking agent and mix them at 400℃ for 1h to obtain a second precursor with a particle size of about 8µm.

[0098] S3: Crosslink and cure the second precursor at 600℃ for 2 hours to obtain the composite precursor;

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

[0100] Example 2

[0101] S1: Dissolve 200g of coal tar in 5000g of ethanol organic solvent, and add 50g of hollow carbon spheres (diameter 50nm~80nm, specific surface area 498m²). 2 The first precursor (with a particle size of approximately 5µm) was uniformly dispersed with 300g of alkyd resin (CAS: 63148-69-6) and spray-dried to obtain a first precursor with a particle size of approximately 5µm.

[0102] S2: Take 100g of the first precursor, 2g of oxidized asphalt, 1g of carboxylated carbon nanotubes and 1g of phthalic acid and mix them at 300℃ for 2h to obtain a second precursor with a particle size of 6µm.

[0103] S3: Crosslink and cure the second precursor at 500℃ for 3 hours to obtain the composite precursor;

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

[0105] Example 3

[0106] S1: Dissolve 400g of coal tar in 5000g of ethanol organic solvent, and add 150g of hollow carbon spheres (diameter 200nm~400nm, specific surface area 293m²). 2 The mixture of 300g fumaric acid resin and 1g fumaric acid resin was dispersed evenly and spray-dried to obtain a first precursor with a particle size of approximately 10µm.

[0107] S2: Mix 100g of the first precursor, 8g of oxidized asphalt, 5g of carboxylated carbon nanotubes and 5g of isophthalic acid crosslinking agent at 450℃ for 0.5h to obtain a second precursor with a particle size of about 12µm.

[0108] S3: Crosslink and cure the second precursor at 650℃ for 1 hour to obtain the composite precursor;

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

[0110] Example 4

[0111] It is basically the same as Example 1, except that the diameter of the hollow carbon spheres is adjusted to 50~80nm.

[0112] Example 5

[0113] It 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 in Example 1, except that the ratio of the first precursor to carboxylated carbon nanotubes is adjusted to 100:10.

[0116] Comparative Example 1

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

[0118] Comparative Example 2

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

[0120] Comparative Example 3

[0121] The process is basically the same as in Example 1, except that carboxylated carbon nanotubes are not added in step S2.

[0122] Comparative Example 4

[0123] The process is basically the same as in Example 1, except that in step S2, the carboxylated carbon nanotubes are replaced with the same weight of ordinary carbon nanotubes.

[0124] Test Example 1

[0125] The porous carbon composite material prepared in Example 1 was tested by scanning electron microscopy (SEM), and the results are as follows: Figure 2 As shown.

[0126] Depend on Figure 2 As can be seen, the material exhibits a secondary granular structure with slight adhesion, uniform size distribution, and particle size between 5μm and 10μm.

[0127] Test Example 2

[0128] 1. Physicochemical property testing:

[0129] The pore volume and pore size of the materials obtained in Examples 1-6 and Comparative Examples 1-4 were tested in accordance with the national standards GB / T-38949-2020 "Determination of Pore Size of Porous Membranes - Standard Particle Method" and GB / T7702.20-2008 "Detection of Pore Volume of Coal-based Activated Carbon". 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 conductivity of the materials obtained in Examples 1-6 and Comparative Examples 1-4 was tested using a four-probe tester.

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

[0132] 2. Compression resistance test:

[0133] The compressive strength of the materials obtained in Examples 1-6 and Comparative Examples 1-4 was tested using the pressure-specific surface area method. This method involves applying a certain pressure to cause a change in the specific surface area of ​​the material, thereby determining its compressive strength. 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 test material is removed. Different specific surface areas are obtained using different pressures.

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

[0135] 3. Electrochemical performance testing:

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

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

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

[0139] Electrochemical performance was performed using a Wuhan Landian CT2001A battery tester. The charge / discharge voltage range was 0.005V to 2.0V, and the charge / discharge rate was 0.1C. The discharge specific capacity and initial efficiency of the corresponding coin cells were tested. At the same time, the cycle performance (0.1C / 0.1C, 100 cycles) of the corresponding coin cells was also tested.

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

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

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

[0143] Table 1

[0144]

[0145] Table 2

[0146]

[0147] Table 3

[0148]

[0149] As can be seen from Tables 1-3, compared with the comparative example, the composite material prepared in the example has a larger specific surface area and a lower powder resistivity. The coin cell assembled using the composite material prepared in the example has a higher discharge specific capacity, first efficiency, cycle performance and diffusion coefficient, and has a lower full charge expansion, resulting in better overall performance.

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

[0151] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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 are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification 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 includes the following steps: An organic carbon source and hollow carbon spheres are mixed in a first process to obtain a first precursor; the organic carbon source includes a first organic carbon source containing a first active group. The first precursor, organic binder, carbon nanotubes and crosslinking agent are mixed in a second process to obtain a second precursor. The carbon nanotube contains a second active group, and both the first and second active groups can react with the crosslinking agent. The second precursor is cross-linked and cured to obtain a composite precursor; The porous carbon composite material is prepared by carbonizing and activating the composite precursor.

2. The preparation method according to claim 1, characterized in that, The first active group includes one or more of carboxyl and carbonyl groups; and / or, The second active group includes one or more of carboxyl and carbonyl groups; and / or, The crosslinking 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, the second organic carbon source including coal tar.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The hollow carbon spheres have a diameter of 50nm~500nm and a specific surface area of ​​100m². 2 / g~500m 2 / g.

5. The preparation method according to claim 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 crosslinking agent is 100:2-8:1-5:1-5; and / or, The organic binder includes oxidized bitumen and oxidized resin; and / or, The crosslinking agent includes one or more of terephthalic acid, phthalic acid, isophthalic acid, gallic acid, pyromellitic acid, perylene 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 conditions for the second mixing include: a temperature of 300℃~450℃ and a time of 0.5h~2h; and / or, The conditions for cross-linking and curing include: a temperature of 500℃ to 650℃ and a time of 1h to 3h.

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℃~900℃ and a time of 1h~3h; and / or, The activation treatment conditions include: the activator includes one or more of carbon dioxide and water vapor, the temperature is 950℃~1100℃, the time is 1h~6h, and the activator flow rate is 100SCCM~500SCCM.

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

10. The porous carbon composite material according to claim 9, characterized in that, One or more of the following conditions must be met; (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 cm³. 3 / g~1.0cm 3 / g; (3) The specific surface area of ​​the porous carbon composite material is 1800 m². 2 / g~2200m 2 / g; (4) The tap density of the porous carbon composite material is 0.3 g / cm³. 3 ~0.8g / cm 3 .

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