An activated carbon-based hard carbon material, a preparation method and application thereof

Abstract

The application provides a kind of hard carbon material based on activated carbon and its preparation method and application, it is related to electrochemical energy storage technical field.The preparation method of hard carbon material based on activated carbon includes: activated carbon is dipped in initiator, is obtained after stirring, drying mixed material;The mixed material is pre-crosslinked with vinyl monomer, then the pre-crosslinked product is heat treated, finally carbonization;The vinyl monomer includes one or more of styrene, divinyl benzene, methyl acrylate, 1,4-butadiene, propylene, acrylonitrile, ethyl acrylate, acrylic acid, acrylamide.The hard carbon material provided by the application is prepared by the preparation method.The hard carbon material provided by the application is used for lithium, sodium ion battery negative material.After activated carbon is filled with vinyl monomer, crosslinking and carbonization, the hard carbon material is prepared, and the electrochemical performance and cycle life are better, the sodium storage capacity is excellent, and it is a better lithium, sodium ion battery negative material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical energy storage, and particularly relates to a hard carbon material based on activated carbon and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of economy, fossil fuels are becoming increasingly depleted and have caused a series of environmental problems, and the global community is vigorously developing renewable energy such as solar energy and wind energy, so the development of high-performance energy storage devices has attracted widespread attention. Among numerous energy storage devices, lithium ion batteries have high energy density and good cycle performance, and have been widely used in electric vehicles, mobile phones and other fields. However, compared with lithium, the more abundant sodium element is more suitable for application in large-scale electric energy storage systems due to its low cost and excellent low-temperature performance. The negative electrode is an important part of the composition of lithium / sodium ion batteries and is a key factor determining the performance of the batteries. The negative electrode material of lithium / sodium ion batteries mainly includes carbon-based materials, transition metal compounds and alloy materials.

[0003] Carbon-based materials are considered to be the most promising negative electrode material due to their safety, non-toxicity, environmental friendliness and low cost. Common carbon-based materials can be divided into hard carbon and soft carbon. Hard carbon material as a negative electrode material for lithium / sodium ion batteries has excellent low-temperature performance, high specific capacity and low cost. The precursors for synthesizing hard carbon currently mainly include biomass, pitch and phenolic resin. Patent CN115385323A uses biomass as a precursor, mixes the precursor with an organic compound containing heteroatoms after pre-carbonization, and obtains a hard carbon material doped with N, P and S heteroatoms after hydrothermal reaction and carbonization. The interlayer spacing of the hard carbon material is effectively improved, and the sodium storage capacity is improved. Patent CN115842131B prepares a N-doped porous hard carbon material by mixing tannic acid, formaldehyde and lysine, which has high capacity and good rate performance. However, as can be seen from the above two patents, the heteroatom-doped hard carbon material can improve the reversible sodium storage capacity, but the cost of the synthesis raw materials is high, and the product yield is difficult to guarantee.

[0004] Patent CN116395665A uses high molecular resin as raw material to obtain spherical high molecular resin after polymerization, filtration and drying, then obtains homogeneous spherical hard carbon by carbonization (heating to 600-1800℃ for 1-5h). Patent CN114044508B uses two different precursors as raw material to obtain precursor microspheres by spray drying, then obtains hard carbon microspheres after carbonization (heating at a rate of 0.5-20℃ / min to 900-1600℃ for 0.5-10h), acid washing and water washing. Patent CN108862235B uses fibrous biomass material as raw material to obtain precursor after washing, drying and grinding, then obtains fibrous hollow hard carbon material after high temperature pyrolysis (heating at a rate of 5℃ / min to 1400℃ for 2h). Patent CN110265645A prepares pitch mixture by heat treating pitch, oil-soluble iron precursor and sulfur additives, then obtains pitch-based carbon nanosheet material after mixing with template agent, carbonization, washing and drying. The above preparation process is complex, long cycle and difficult to be applied on a large scale.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The present application aims to provide a hard carbon material based on activated carbon and a preparation method and application thereof to solve the above problems.

[0007] To achieve the above object, the present application adopts the following technical solution:

[0008] A preparation method of a hard carbon material based on activated carbon, comprising: dipping activated carbon in an initiator, stirring and drying to obtain a mixture; pre-crosslinking the mixture with a vinyl monomer, then heat treating the pre-crosslinking product, and finally carbonizing to obtain the hard carbon material.

[0009] The vinyl monomer comprises one or more of styrene, divinylbenzene, methyl acrylate, 1,4-butadiene, propylene, acrylonitrile, ethyl acrylate, acrylic acid and acrylamide.

[0010] The preparation of hard carbon material based on activated carbon has the advantages of high yield, low cost and simple process. However, if the process is not creatively designed, it is easy to cause excessive sintering and deactivation. The method of the present application utilizes the porosity of activated carbon to load resin in the voids of activated carbon and realize polymerization and crosslinking in the voids. On the one hand, it overcomes the defect of possible excessive sintering, and on the other hand, it realizes deep modification of activated carbon, so that the hard carbon material prepared therefrom has better electrochemical performance.

[0011] Preferably, the initiator comprises one or more of azobisisobutyronitrile, benzoyl peroxide, potassium persulfate, dicumyl peroxide, tert-butyl peroxybenzoate, diisopropyl peroxydicarbonate;

[0012] Further preferably, the initiator is used in an amount of 0.1% to 2% of the amount of the vinyl monomer.

[0013] Preferably, the temperature of the impregnation is 30°C to 80°C.

[0014] The temperature of the impregnation is preferably necessary because too high a temperature would cause the initiator to volatilize, and too low a temperature would not allow the initiator to perform its function.

[0015] Preferably, the mass ratio of the vinyl monomer to the activated carbon is 0.2:1 to 3:1.

[0016] Preferably, the temperature of the pre-crosslinking treatment is 100°C to 150°C, the time is 0.5h to 5h, and the number of times is 1 to 5.

[0017] Further preferably, the pre-crosslinking treatment comprises vapor deposition or liquid immersion.

[0018] The means of the pre-crosslinking treatment depends on the type of the vinyl monomer, and the specific pre-crosslinking means and process are determined according to the boiling point of the vinyl monomer. Generally, liquid immersion is used for high-boiling-point vinyl monomers, and vapor deposition is used for low-boiling-point vinyl monomers.

[0019] Preferably, the atmosphere of the heat treatment comprises nitrogen, argon, or air.

[0020] Further preferably, the temperature of the heat treatment is 80°C to 400°C, and the treatment time is 0.5h to 5h.

[0021] Preferably, the carbonization comprises: increasing the temperature to 800°C-1600°C at a temperature increase rate of 1°C to 10°C / min.

[0022] Optionally, the preparation method further comprises: before the impregnation, pretreating the activated carbon.

[0023] Preferably, the pretreatment comprises loading the vinyl monomer on the activated carbon.

[0024] Further preferably, the loading comprises vapor deposition or liquid immersion.

[0025] The vinyl monomer is directly loaded in the internal pores of the activated carbon by carrying out the loading treatment of the vinyl monomer before the activated carbon is impregnated with the initiator, so that the pore filling loading can be better achieved, and the loading achieved by the subsequent pre-crosslinking treatment cooperates with the loading, that is, the vinyl monomer is filled on both sides of the initiator, the effect of the initiator can be maximized, the amount of impurities introduced into the system is reduced, the subsequent purification step is simplified, the subsequent crosslinking polymerization reaction can be more fully carried out, the effect is better, and the performance of the product is further improved.

[0026] The application provides a hard carbon material prepared by the preparation method.

[0027] The application further provides application of the hard carbon material, including application to a lithium or sodium ion battery negative electrode material.

[0028] The prior art has problems of complex preparation process, long production cycle and high cost for preparing a commonly used negative electrode material of a lithium or sodium ion battery. The application first overcomes the above problems, and a hard carbon material based on activated carbon is prepared by using a simpler and more cost-effective method, and a large number of closed pores are formed by filling treatment of the activated carbon rich in pores, more sodium ion storage spaces are provided, the first coulombic efficiency is better, and the specific capacity is higher, so that the hard carbon material is used as the negative electrode material of the lithium or sodium ion battery, and the performance of the battery can be significantly improved.

[0029] The application has the following beneficial effects:

[0030] The prior art only involves surface modification of activated carbon, and the prepared material is not a hard carbon material. The application prepares a hard carbon material based on activated carbon, involves filling modification of pores of the activated carbon in the process, and initiates polymerization of a vinyl monomer in the pores, and the hard carbon material is prepared by high-temperature carbonization, so that the operation process is simple, the cost is low, and the application is suitable for industrial production.

[0031] The carbon-coated hard carbon material prepared by filling and loading the vinyl monomer in the activated carbon and then carbonizing has good electrochemical performance and cycle life, and exhibits excellent sodium storage capacity.

[0032] The hard carbon material based on activated carbon provided by the application has a large number of closed pores by filling treatment of the activated carbon rich in pores, more sodium ion storage spaces are provided, the first coulombic efficiency is better, and the specific capacity is higher, compared with a conventional hard carbon material, so that the hard carbon material is more suitable for application to a lithium or sodium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art of the present application, the drawings required to be used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0034] Figure 1 Appearance morphology of the hard carbon material based on activated carbon obtained in Example 1;

[0035] Figure 2 Initial charge-discharge curve graph of the sodium ion battery prepared by the hard carbon material obtained in Example 1 at 0.5C;

[0036] Figure 3 Second round charge-discharge curve graph of the sodium ion battery prepared by the hard carbon material obtained in Example 1 at 0.5C. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0038] Example 1

[0039] The hard carbon material based on activated carbon is prepared according to the preparation method provided by the present application, and the specific steps are as follows:

[0040] S1: The activated carbon is immersed into a potassium persulfate solution with a temperature of 30℃, and stirred and mixed uniformly, and then the mixture is dried to obtain a mixture;

[0041] S2: The divinylbenzene is deposited on the mixture obtained in S1 by gas phase deposition through a tubular furnace in a nitrogen atmosphere, the mass of potassium persulfate is 0.1% of the mass of divinylbenzene, the mass ratio of divinylbenzene to activated carbon is 2:1, the gas phase deposition temperature is 110℃, the deposition time is 0.5h, and the deposition times is 1;

[0042] S3: The product obtained in S2 is heat treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat treatment temperature is 300℃, and the treatment time is 2h;

[0043] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 4℃ / min to 1200℃ to obtain the hard carbon material based on activated carbon.

[0044] The surface morphology of the product obtained in this example is shown in Figure 1

[0045] Example 2

[0046] The hard carbon material based on activated carbon is prepared by the preparation method provided in the application, and the specific steps are as follows:

[0047] S1: The activated carbon is immersed into a benzoyl peroxide solution with a temperature of 40°C, and is stirred and uniformly mixed, and then the mixture is dried to obtain a mixture;

[0048] S2: The styrene is deposited on the mixture obtained in S1 by gas phase deposition through a tube furnace in a nitrogen atmosphere, the mass of potassium persulfate is controlled to be 0.4% of the mass of the styrene, the mass ratio of the styrene to the activated carbon is 0.2:1, the gas phase deposition temperature is 70°C, the deposition time is 3h, and the deposition times is 2;

[0049] S3: The product obtained in S2 is subjected to heat treatment in an argon atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat treatment temperature is 300°C, and the treatment time is 2h;

[0050] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 4°C / min to 1200°C to obtain the hard carbon material based on activated carbon.

[0051] Example 3

[0052] The hard carbon material based on activated carbon is prepared by the preparation method provided in the application, and the specific steps are as follows:

[0053] S1: The activated carbon is immersed into a dicumyl peroxide solution with a temperature of 50°C, and is stirred and uniformly mixed, and then the mixture is dried to obtain a mixture;

[0054] S2: The mixture obtained in S1 is immersed into a methyl acrylate solution, and the methyl acrylate is loaded on the mixture obtained in S1 by liquid phase immersion, the mass of the dicumyl peroxide is controlled to be 0.8% of the mass of the methyl acrylate, the mass ratio of the methyl acrylate to the activated carbon is 1:1, the liquid phase immersion temperature is 90°C, the immersion time is 2h, and the immersion times is 3;

[0055] S3: The product obtained in S2 is subjected to heat treatment in an air atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat treatment temperature is 80°C, and the treatment time is 2h;

[0056] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 4°C / min to 1200°C to obtain the hard carbon material based on activated carbon.

[0057] ​Example 4

[0058] The hard carbon material based on activated carbon is prepared by the preparation method provided in the present application, and the specific steps are as follows:

[0059] S1: The activated carbon is immersed into an azobisisobutyronitrile solution with a temperature of 60°C, and is stirred and uniformly mixed, and then the mixture is dried to obtain a mixture;

[0060] S2: Acrylonitrile is vapor deposited on the mixture obtained in S1 by a tube furnace in a nitrogen atmosphere, the mass of azobisisobutyronitrile is controlled to be 1.2% of the mass of acrylonitrile, the mass ratio of acrylonitrile to activated carbon is 2:1, the vapor deposition temperature is 110°C, the deposition time is 1h, and the deposition times is 4;

[0061] S3: The product obtained in S2 is heat treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat treatment temperature is 100°C, and the treatment time is 2h;

[0062] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 4°C / min to 1200°C to obtain the hard carbon material based on activated carbon.

[0063] Example 5

[0064] The hard carbon material based on activated carbon is prepared by the preparation method provided in the present application, and the specific steps are as follows:

[0065] S1: The activated carbon is immersed into a tert-butyl peroxy benzoate solution with a temperature of 70°C, and is stirred and uniformly mixed, and then the mixture is dried to obtain a mixture;

[0066] S2: Propylene is vapor deposited on the mixture obtained in S1 by a tube furnace in a nitrogen atmosphere, the mass of tert-butyl peroxy benzoate is controlled to be 1.6% of the mass of propylene, the mass ratio of propylene to activated carbon is 3:1, the vapor deposition temperature is 130°C, the deposition time is 3h, and the deposition times is 1;

[0067] S3: The product obtained in S2 is heat treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat treatment temperature is 200°C, and the treatment time is 2h;

[0068] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 4°C / min to 1200°C to obtain the hard carbon material based on activated carbon.

[0069] Example 6

[0070] The hard carbon material based on activated carbon is prepared by the preparation method provided in the present application, and the specific steps are as follows:

[0071] S1: The activated carbon is immersed into a diisopropyl peroxydicarbonate solution with a temperature of 80°C and stirred to mix uniformly, and then the mixture is dried to obtain a mixture;

[0072] S2: 1,4-butadiene is vapor-deposited onto the mixture obtained in S1 in a nitrogen atmosphere through a tube furnace, the mass of diisopropyl peroxydicarbonate is controlled to be 2% of the mass of 1,4-butadiene, the mass ratio of 1,4-butadiene to activated carbon is 2:1, the vapor-deposition temperature is 150°C, the deposition time is 5h, and the deposition frequency is 1 time;

[0073] S3: The product obtained in S2 is heat-treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat-treatment temperature is 300°C, and the treatment time is 2h;

[0074] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 8°C / min to 1200°C to obtain an activated carbon-based hard carbon material.

[0075] Example 7

[0076] An activated carbon-based hard carbon material is prepared according to the preparation method provided by the present application, and the specific steps are as follows:

[0077] S1: The activated carbon is immersed into an azobisisobutyronitrile solution with a temperature of 60°C and stirred to mix uniformly, and then the mixture is dried to obtain a mixture;

[0078] S2: Styrene is vapor-deposited onto the mixture obtained in S1 in a nitrogen atmosphere through a tube furnace, the mass of azobisisobutyronitrile is controlled to be 1.2% of the mass of styrene, the mass ratio of styrene to activated carbon is 2:1, the vapor-deposition temperature is 110°C, the deposition time is 3h, and the deposition frequency is 1 time;

[0079] S3: The product obtained in S2 is heat-treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat-treatment temperature is 400°C, and the treatment time is 0.5h;

[0080] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 2°C / min to 1200°C to obtain an activated carbon-based hard carbon material.

[0081] Example 8

[0082] An activated carbon-based hard carbon material is prepared according to the preparation method provided by the present application, and the specific steps are as follows:

[0083] S1: The activated carbon is immersed into a benzoyl peroxide solution with a temperature of 60°C and stirred to mix uniformly, and then the mixture is dried to obtain a mixture;

[0084] S2: The mixture obtained in S1 is impregnated in a solution of ethyl acrylate. Ethyl acrylate is loaded onto the mixture obtained in S1 through liquid phase impregnation. The mass of benzoyl peroxide is controlled to be 1.2% of the mass of ethyl acrylate, the mass ratio of ethyl acrylate to activated carbon is 2:1, the liquid phase impregnation temperature is 50℃, the impregnation time is 2h, and the number of impregnations is 2.

[0085] S3: The product obtained in S2 is heat-treated in air to promote further cross-linking and pre-carbonization of the vinyl monomers. The heat treatment temperature is 300℃ and the treatment time is 1h.

[0086] S4: The product of S3 was heated to 1200℃ in an argon atmosphere at a heating rate of 4℃ / min to carbonize it, thus obtaining a hard carbon material based on activated carbon.

[0087] Example 9

[0088] The preparation method provided by the present invention for preparing hard carbon materials based on activated carbon includes the following specific steps:

[0089] S1: Impregnate activated carbon in a potassium persulfate solution at 60°C and stir until homogeneous. Then dry the mixture to obtain a mixture.

[0090] S2: The mixture obtained in S1 is impregnated in an acrylic acid solution. The acrylic acid is loaded onto the mixture obtained in S1 through liquid phase impregnation. The mass of potassium persulfate is controlled to be 1.2% of the mass of acrylic acid, the mass ratio of acrylic acid to activated carbon is 2:1, the liquid phase impregnation temperature is 70℃, the impregnation time is 4h, and the number of impregnations is 5.

[0091] S3: The product obtained in S2 is heat-treated in a nitrogen atmosphere to promote further crosslinking and pre-carbonization of the vinyl monomers. The heat treatment temperature is 300℃ and the treatment time is 2h.

[0092] S4: The product of S3 was heated to 800℃ in an argon atmosphere at a heating rate of 6℃ / min to carbonize it, thereby obtaining a hard carbon material based on activated carbon.

[0093] Example 10

[0094] The preparation method provided by the present invention for preparing hard carbon materials based on activated carbon includes the following specific steps:

[0095] S1: Impregnate activated carbon in a dicumyl peroxide solution at 60°C and stir until homogeneous. Then dry the mixture to obtain a mixture.

[0096] S2: Acrylamide is vapor-deposited onto the mixture obtained in S1 in a nitrogen atmosphere by a tube furnace, the mass of dicumyl peroxide is 1.2% of the mass of acrylamide, the mass ratio of acrylamide to activated carbon is 2:1, the vapor-deposition temperature is 110°C, the deposition time is 2h, and the deposition times is 2;

[0097] S3: The product obtained in S2 is heat-treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat-treatment temperature is 300°C, and the treatment time is 3h;

[0098] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 1°C / min to 1000°C to obtain the activated carbon-based hard carbon material.

[0099] Example 11

[0100] According to the preparation method provided by the present application, the activated carbon-based hard carbon material is prepared, and the specific steps are as follows:

[0101] S1: The activated carbon is immersed in an azobisisobutyronitrile solution at a temperature of 60°C and stirred and mixed uniformly, and then the mixture is dried to obtain a mixture;

[0102] S2: The mixture obtained in S1 is immersed in a mixed solution of styrene and methyl acrylate with a mass ratio of 1:1, and styrene and methyl acrylate are loaded onto the mixture obtained in S1 by liquid-phase immersion, the mass of azobisisobutyronitrile is 1.2% of the mass of the vinyl monomer, the mass ratio of styrene and methyl acrylate to activated carbon is 2:1, the liquid-phase immersion temperature is 90°C, the immersion time is 2h, and the immersion times is 2;

[0103] S3: The product obtained in S2 is heat-treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomer, the heat-treatment temperature is 300°C, and the treatment time is 4h;

[0104] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 10°C / min to 1200°C to obtain the activated carbon-based hard carbon material.

[0105] Example 12

[0106] According to the preparation method provided by the present application, the activated carbon-based hard carbon material is prepared, and the specific steps are as follows:

[0107] S1: The activated carbon is immersed in an azobisisobutyronitrile solution at a temperature of 60°C and stirred and mixed uniformly, and then the mixture is dried to obtain a mixture;

[0108] S2: A mixture of styrene and acrylonitrile with a mass ratio of 1:2 is vapor deposited onto the mixture obtained in S1 in a nitrogen atmosphere by a tube furnace, the mass of azobisisobutyronitrile is 1.2% of the mass of the mixture of styrene and acrylonitrile, the mass ratio of the mixture of styrene and acrylonitrile to activated carbon is 2:1, the vapor deposition temperature is 110℃, the deposition time is 2h, and the deposition times is 2 times;

[0109] S3: The product obtained in S2 is heat treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomers, the heat treatment temperature is 300℃, and the treatment time is 5h;

[0110] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 4℃ / min to 1400℃ to obtain the activated carbon-based hard carbon material.

[0111] Example 13

[0112] The activated carbon-based hard carbon material is prepared according to the preparation method provided by the present application, and the specific steps are as follows:

[0113] S1: The activated carbon is immersed in an azobisisobutyronitrile solution with a temperature of 60℃ and stirred and mixed uniformly, and then the mixture is dried to obtain a mixture;

[0114] S2: The mixture obtained in S1 is immersed in a mixed solution of acrylonitrile and methyl acrylate with a mass ratio of 1:3, and acrylonitrile and methyl acrylate are loaded onto the mixture obtained in S1 by liquid phase immersion, the mass of azobisisobutyronitrile is 1.2% of the mass of the vinyl monomers, the mass ratio of the total amount of acrylonitrile and methyl acrylate to activated carbon is 2:1, the liquid phase immersion temperature is 90℃, the immersion time is 2h, and the immersion times is 2 times;

[0115] S3: The product obtained in S2 is heat treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomers, the heat treatment temperature is 300℃, and the treatment time is 2h;

[0116] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 4℃ / min to 1600℃ to obtain the activated carbon-based hard carbon material.

[0117] Example 14

[0118] The activated carbon-based hard carbon material is prepared according to the preparation method provided by the present application, and the specific steps are as follows:

[0119] S1: The activated carbon is immersed in an azobisisobutyronitrile solution with a temperature of 60℃ and stirred and mixed uniformly, and then the mixture is dried to obtain a mixture;

[0120] S2: A mixture of divinylbenzene, acrylic acid and methyl acrylate with a mass ratio of 1:1:1 is vapor deposited onto the mixture obtained in S1 in a nitrogen atmosphere by a tube furnace, the mass of azobisisobutyronitrile is 1.2% of the mass of the mixture of divinylbenzene, acrylic acid and methyl acrylate, the mass ratio of the mixture of divinylbenzene, acrylic acid and methyl acrylate to activated carbon is 2:1, the vapor deposition temperature is 110°C, the deposition time is 2h, and the deposition times is 2;

[0121] S3: The product obtained in S2 is heat treated in an argon atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomers, the heat treatment temperature is 300°C, and the treatment time is 2h;

[0122] S4: The product of S3 is carbonized in a nitrogen atmosphere at a heating rate of 10°C / min to 1200°C to obtain the activated carbon-based hard carbon material.

[0123] Example 15

[0124] The activated carbon-based hard carbon material is prepared according to the preparation method provided by the present application, and the specific steps are as follows:

[0125] S1: The activated carbon is immersed in an azobisisobutyronitrile solution with a temperature of 60°C and stirred and mixed uniformly, and then the mixture is dried to obtain a mixture;

[0126] S2: The mixture obtained in S1 is immersed in a mixed solution of acrylonitrile, ethyl acrylate and methyl acrylate with a mass ratio of 1:1:1, and acrylonitrile, ethyl acrylate and methyl acrylate are loaded onto the mixture obtained in S1 by liquid phase immersion, the mass of azobisisobutyronitrile is 1.2% of the mass of the vinyl monomers, the mass ratio of the total amount of the vinyl monomers to activated carbon is 2:1, the liquid phase immersion temperature is 90°C, the immersion time is 2h, and the immersion times is 2;

[0127] S3: The product obtained in S2 is heat treated in a nitrogen atmosphere to promote further cross-linking and pre-carbonization of the vinyl monomers, the heat treatment temperature is 300°C, and the treatment time is 2h;

[0128] S4: The product of S3 is carbonized in an argon atmosphere at a heating rate of 4°C / min to 1200°C to obtain the activated carbon-based hard carbon material.

[0129] Example 16

[0130] The difference from Example 15 is that, before the S1 step, the activated carbon is pretreated, specifically: a mixed solution of acrylonitrile, ethyl acrylate and methyl acrylate with a mass ratio of 1:1:1 is prepared, then the mixed solution is heated to 90°C and the activated carbon is immersed therein for 2h, and then taken out and dried for use. The subsequent steps are the same as those of Example 15.

[0131] Comparative Example 1

[0132] The hard carbon material provided by Comparative Example 1 is a conventional activated carbon.

[0133] Electrochemical performance of the hard carbon materials provided by the test examples and the comparative example: the hard carbon material prepared by the examples and the conventional activated carbon of Comparative Example 1 were respectively prepared as active materials to prepare sodium ion batteries, and the reversible capacity and the first cycle coulombic efficiency were tested.

[0134] The specific test steps are as follows: grinding and mixing for 30 min according to the ratio of active material: acetylene black: polyvinylidene fluoride of 80:10:10, then adding 1 times mass of N-methyl pyrrolidone liquid, stirring for 1 h, uniformly stirring, coating on a copper foil, vacuum drying at 110°C for 12 h, and cutting into a circular electrode with a diameter of 8 mm. The assembly of the simulation battery was carried out in an Ar atmosphere glove box, using metallic sodium as the counter electrode, using 1 mole of NaClO4 dissolved in 1L volume ratio of 1:1 ethylene carbonate and diethyl carbonate solution as the electrolyte, preparing a button cell, and evaluating the electrochemical performance by testing.

[0135] The test results are shown in Table 1 and Figure 2 、 3 , Figure 2 The initial charge-discharge curve of the sodium ion battery prepared by the hard carbon material prepared in Example 1 at 0.5C is shown in FIG. 1, Figure 3 The second cycle charge-discharge curve of the sodium ion battery prepared by the hard carbon material prepared in Example 1 at 0.5C is shown in FIG. 2, Figure 2 It can be seen that the initial energy density can reach 236mAh / g at a current density of 0.5C, Figure 3 It can be seen that the second cycle energy density can reach 210mAh / g at a current density of 0.5C, showing a first coulombic efficiency of 81.1%.

[0136] Table 1: Electrochemical performance test results of the materials provided by Examples 1-15 and Comparative Example 1

[0137]

[0138] As can be seen from Table 1, the sodium ion battery prepared by the hard carbon material provided by the examples has higher first coulombic efficiency and energy density, and exhibits excellent electrochemical performance.

[0139] Please note that the technical features of the above embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered as within the scope of the present disclosure. The above embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but should not be understood as a limitation on the patent scope of the present application. It should be noted that for those skilled in the art, some modifications and improvements can be made without departing from the concept of the present application, and these are within the scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A method for preparing a hard carbon material based on activated carbon, characterized in that, include: Activated carbon is impregnated with an initiator, stirred, and dried to obtain a mixture; the mixture is pre-crosslinked with vinyl monomers, the pre-crosslinked product is then heat-treated, and finally carbonized to obtain the final product. The vinyl monomers include one or more of styrene, divinylbenzene, methyl acrylate, 1,4-butadiene, propylene, acrylonitrile, ethyl acrylate, acrylic acid, and acrylamide; The pre-crosslinking treatment is as follows: the vinyl monomer is polymerized and crosslinked within the pores of activated carbon.

2. The preparation method according to claim 1, characterized in that, The initiator includes one or more of azobisisobutyronitrile, benzoyl peroxide, potassium persulfate, dicumyl peroxide, tert-butyl peroxide, and diisopropyl peroxide. The amount of the initiator is 0.1% to 2% of the amount of the vinyl monomer.

3. The preparation method according to claim 1, characterized in that, The impregnation temperature is 30℃~80℃.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the vinyl monomer to the activated carbon is 0.2:1 to 3:

1.

5. The preparation method according to claim 1, characterized in that, The pre-crosslinking treatment is performed at a temperature of 100℃~150℃ for a time of 0.5h~5h, and is repeated 1~5 times. The pre-crosslinking treatment includes vapor deposition or liquid impregnation.

6. The preparation method according to claim 1, characterized in that, The atmosphere for the heat treatment includes nitrogen, argon, or air. The heat treatment temperature is 80℃~400℃, and the treatment time is 0.5h~5h.

7. The preparation method according to claim 1, characterized in that, The carbonization process includes heating to 800℃-1600℃ at a heating rate of 1℃~10℃ / min.

8. The preparation method according to any one of claims 1-7, characterized in that, The preparation method further includes: pretreating the activated carbon before impregnation; The pretreatment includes loading vinyl monomers onto the activated carbon; The load includes vapor deposition or liquid impregnation.

9. A hard carbon material, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. An application of the hard carbon material as described in claim 9, characterized in that, Including materials used in lithium and sodium-ion batteries as anodes.

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