A bio-asphalt-based hard carbon composite material and a preparation method thereof

Abstract

The application provides a bio-asphalt-based composite hard carbon composite material and a preparation method thereof. The bio-asphalt-based composite hard carbon composite material comprises asphalt, imidazole ionic liquid, amino resin, sodium molybdate, carbon precursor, aldehyde-based crosslinking agent and oxidant, and the mass fractions of the above materials are as follows: 100 parts of asphalt, 500-2000 parts of imidazole ionic liquid, 100-200 parts of amino resin, 1-5 parts of sodium molybdate, 10-30 parts of aldehyde-based crosslinking agent and 1-5 parts of oxidant. Through crosslinking of the aldehyde-based crosslinking agent and the oxidant, oxidation forms abundant chemical groups on the surface of the material, the sodium storage function of the material is improved, the carbonized sodium molybdate realizes molybdenum-doped hard carbon, the specific capacity of the hard carbon composite material is improved by using the high specific capacity of molybdenum itself, and the transmission rate of sodium ions in the charging and discharging process is improved by doping sodium ions, so that the rate performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological-asphalt-based composite hard carbon composite materials, in particular to a biological-asphalt-based composite hard carbon composite material and a preparation method thereof. BACKGROUND

[0002] Hard carbon, as a kind of amorphous carbon which is difficult to graphitize, has a structure of random layer structure, and has characteristics such as more pores, good isotropy, larger specific surface area and more defects, which causes the first efficiency of the material to be low and the compaction density to be low, and when the material is applied to a full battery, the positive electrode capacity of the material is low, which reduces the energy density. The main methods to improve the compaction density and the first efficiency of the hard carbon material include: selecting raw materials with less defects, small lamellas and good anisotropy, coating the surface of the raw materials, doping to improve the kinetic performance of the material, and improving the capacity of the material. The raw materials used in the current marketized hard carbon mainly include resin materials, asphalt-based materials, coal-based raw materials and biomass materials. The resin materials have high specific capacity, poor kinetics, high cost, high consistency and low first efficiency, and can only be used in high-energy-density sodium ion batteries. The asphalt-based materials have low specific capacity, high first efficiency, good kinetics, and are widely available and low in cost, and are suitable for low-energy-density sodium ion batteries. However, the specific capacity of the material needs to be improved by oxidation and cross-linking, and the capacity of the material needs to be improved. Therefore, the two different hard carbon raw materials need to be mixed to play their respective advantages, improve the energy, and take into account the kinetics, first efficiency and cost.

[0003] However, the current marketized hard carbon has low specific capacity, low first efficiency and high cost. SUMMARY

[0004] (I) Technical problems to be solved

[0005] In view of the deficiencies in the prior art, the present application provides a biological-asphalt-based composite hard carbon composite material and a preparation method thereof, which improves the problem of low specific capacity, low first efficiency and high cost of hard carbon.

[0006] (II) Technical solutions

[0007] To achieve the above object, the present application is implemented by the following technical solutions: a biological-asphalt-based composite hard carbon composite material, comprising:

[0008] The mass fraction of the above-mentioned materials is as follows: 100 parts of asphalt, 500-2000 parts of imidazole ionic liquid, 100-200 parts of amino resin, 1-5 parts of sodium molybdate, 100 parts of carbon precursor, 10-30 parts of aldehyde-based cross-linking agent, and 1-5 parts of oxidizing agent.

[0009] A method for preparing a bio-asphalt-based hard carbon composite material, comprising the following steps:

[0010] S1, preparing the required imidazole ionic liquid as a solvent according to the above proportion, then gradually adding asphalt powder into the imidazole ionic liquid, stirring and heating to 50℃ until the asphalt is completely dissolved in the imidazole ionic liquid to form a uniform mixed solution;

[0011] S2, in the mixed solution, adding the required amount of amino resin and sodium molybdate in 3-5 times, continuously stirring the mixture, heating the reaction system to a temperature range of 100-200℃ to ensure uniform dispersion and reaction, and maintaining the reaction time for 1-6 hours to make the reaction proceed, to obtain a reaction mixture;

[0012] S3, transferring the reaction mixture to filter paper for filtration, and transferring the obtained filter residue to a vacuum drying oven for vacuum drying at a temperature of 80℃ for 24h to obtain a hard carbon precursor material;

[0013] S4, placing the hard carbon precursor material into a container, gradually adding the required amount of aldehyde-based crosslinking agent and oxidizing agent, and uniformly mixing using a magnetic stirrer, continuously stirring the mixture to ensure that the aldehyde-based crosslinking agent and the oxidizing agent are uniformly dispersed in the hard carbon precursor, to obtain a precursor mixture;

[0014] S5, transferring the precursor mixture to a rotary furnace device for curing reaction at a temperature range of 100-200℃ for 1-6 hours;

[0015] S6, after curing, transferring the obtained material to a tube furnace, introducing oxygen, and gradually heating to 1000-1400℃ for carbonization reaction for 1-6 hours to obtain a hard carbon composite material.

[0016] Preferably, the amino resin in step S2 is one of urea-formaldehyde resin, melamine resin, and benzene melamine resin, and the aldehyde-based crosslinking agent in step S4 is one of glutaraldehyde, eicosane dialdehyde, and p-xylylene.

[0017] Preferably, the imidazole ionic liquid in step S1 is one of 1-butyl-3-methylimidazole bromide, 1-ethyl-3-methylimidazole bromide, 1-propenyl-3-methylimidazole bromide, 1-butyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole chloride, or 1-propenyl-3-methylimidazole chloride.

[0018] Preferably, the oxidizing agent in step S4 is one of ammonium persulfate and sodium persulfate.

[0019] Preferably, the stirring in step S1 uses a magnetic stirrer, the heating in step S2 uses a hot plate, and the oxygen flow in step S6 is typically 100-1000 cubic centimeters per minute.

[0020] (III) Beneficial Effects

[0021] The present application provides a bio-asphalt-based composite hard carbon composite material and a preparation method thereof. The present application has the following beneficial effects:

[0022] Through cross-linking of the aldehyde-based cross-linking agent and the oxidizing agent, oxidation forms abundant chemical groups on the surface of the material, improving the sodium storage function of the material. Meanwhile, the carbonized sodium molybdate realizes molybdenum-doped hard carbon, uses the high specific capacity of molybdenum itself to improve the specific capacity of the hard carbon composite material, and uses the doping of sodium ions to improve the transmission rate of sodium ions in the charging and discharging process, thereby improving the rate performance. The present application also uses the characteristics of the amino resin-based hard carbon, such as high specific capacity and good consistency, and the characteristics of the asphalt material, such as high compaction density and good isotropy, to improve the fast-charging performance of the material. In addition, the sodium molybdate generates sodium-doped nanometer microporous holes in the carbonization process, thereby improving the sodium storage function of the material. Meanwhile, the asphalt-based material is dissolved in the imidazole cross-linking agent, so that the asphalt is easy to form a cross-linked structure. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The present application is a metallographic diagram of the material. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] Embodiment One:

[0026] The present application provides a bio-asphalt-based composite hard carbon composite material, which comprises asphalt, imidazole ionic liquid, amino resin, sodium molybdate, carbon precursor, aldehyde-based cross-linking agent, and oxidizing agent. The mass fraction of the above-mentioned materials is as follows: 100 parts of asphalt, 1000 parts of 1-butyl-3-methyl imidazole bromide, 150 parts of urea-formaldehyde resin, 3 parts of sodium molybdate, 20 parts of glutaraldehyde, and 3 parts of ammonium persulfate.

[0027] A bio-asphalt-based composite hard carbon composite material preparation method comprises the following steps:

[0028] S1, prepare the required 1-butyl-3-methylimidazole bromide as a solvent according to the above proportion, then gradually add the asphalt powder to the 1-butyl-3-methylimidazole bromide, stir and heat to 50℃ until the asphalt is completely dissolved in the imidazole ionic liquid to form a uniform mixed solution; stirring is performed using a magnetic stirrer.

[0029] S2, in the mixed solution, add the required amount of urea-formaldehyde resin and sodium molybdate in 4 times, continuously stir the mixture, heat the reaction system to a temperature range of 150℃ to ensure uniform dispersion and reaction, and maintain the reaction time for 3 hours to make the reaction proceed to obtain a reaction mixture;

[0030] S3, transfer the reaction mixture to filter paper for filtration, transfer the obtained filter residue to a vacuum drying oven, vacuum dry at a temperature of 80℃ for 24h to obtain a hard carbon precursor material;

[0031] S4, place the hard carbon precursor material into a container, gradually add the required amount of glutaraldehyde and ammonium persulfate, and uniformly mix using a magnetic stirrer, continuously stir the mixture to ensure uniform dispersion of the glutaraldehyde and ammonium persulfate to obtain a precursor mixture;

[0032] S5, transfer the precursor mixture to a rotary furnace device and perform a curing reaction at a temperature range of 150℃ for 3 hours;

[0033] S6, transfer the material obtained after curing to a tube furnace, introduce oxygen (flow rate 500 cubic centimeters / minute), and gradually heat to 1200℃ to perform a carbonization reaction for 3 hours to obtain a hard carbon composite material.

[0034] Example two:

[0035] The embodiment of the present application provides a bio-asphalt-based composite hard carbon composite material, which comprises asphalt, imidazole ionic liquid, amino resin, sodium molybdate, carbon precursor, aldehyde-based crosslinking agent and oxidizing agent, and the mass fraction of the above-mentioned materials is: asphalt 100 parts, 1-ethyl-3-methylimidazole bromide 500 parts, melamine resin 100 parts, sodium molybdate 1 part, eicosane dialdehyde 10 parts, and sodium persulfate 1 part.

[0036] A bio-asphalt-based composite hard carbon composite material preparation method, comprising the following steps:

[0037] S1, prepare the required 1-butyl-3-methylimidazole bromide as a solvent according to the above proportion, then gradually add the asphalt powder to the 1-butyl-3-methylimidazole bromide, stir and heat to 50℃ until the asphalt is completely dissolved in the imidazole ionic liquid to form a uniform mixed solution; stirring is performed using a magnetic stirrer.

[0038] S2, in the mixed solution, add the required amount of melamine resin and sodium molybdate in 3 times, continue to stir the mixture, heat the reaction system to the temperature range of 100℃, to ensure uniform dispersion and reaction, and keep the reaction time for 6 hours, to make the reaction proceed, to obtain a reaction mixture;

[0039] S3, transfer the reaction mixture to filter paper for filtration, transfer the obtained filter residue to a vacuum drying oven, vacuum dry at 80℃ for 24h, to obtain a hard carbon precursor material;

[0040] S4, put the hard carbon precursor material into a container, gradually add the required amount of eicosane dialdehyde and sodium persulfate, and uniformly mix using a magnetic stirrer, continue to stir the mixture, to ensure that eicosane dialdehyde and sodium persulfate are uniformly dispersed, to obtain a precursor mixture;

[0041] S5, transfer the precursor mixture to a rotary furnace device, and perform a solidification reaction at a temperature range of 100℃ for 6 hours;

[0042] S6, transfer the material obtained after solidification to a tube furnace, pass in oxygen (flow rate 100 cubic centimeters / minute), and gradually heat to 1000℃, to perform a carbonization reaction for 6 hours, to obtain a hard carbon composite material.

[0043] Example three:

[0044] The embodiment of the present application provides a bio-asphalt-based composite hard carbon composite material, which comprises asphalt, imidazole ionic liquid, amino resin, sodium molybdate, carbon precursor, aldehyde-based crosslinking agent, and oxidizing agent, and the mass fraction of the above-mentioned materials is: 100 parts of asphalt, 2000 parts of 1-propenyl-3-methyl imidazole bromide, 200 parts of benzene melamine resin, 5 parts of sodium molybdate, 5 parts of p-phenylenediamine, and 1 part of ammonium persulfate.

[0045] A bio-asphalt-based composite hard carbon composite material preparation method, comprising the following steps:

[0046] S1, prepare the required 1-propenyl-3-methyl imidazole bromide as a solvent according to the above-mentioned proportion, then gradually add the asphalt powder into the 1-propenyl-3-methyl imidazole bromide, stir and heat to 50℃, until the asphalt is completely dissolved in the imidazole ionic liquid, to form a uniform mixed solution; the stirring is performed by using a magnetic stirrer;

[0047] S2, in the mixed solution, add the required amount of benzene melamine resin and sodium molybdate in 5 times, continue to stir the mixture, heat the reaction system to the temperature range of 200℃, to ensure uniform dispersion and reaction, and keep the reaction time for 1 hour, to make the reaction proceed, to obtain a reaction mixture;

[0048] S3, the reaction mixture was transferred to filter paper for filtration, and the obtained filter residue was transferred to a vacuum drying oven for vacuum drying at a temperature of 80°C for 24h to obtain a hard carbon precursor material;

[0049] S4, the hard carbon precursor material was placed in a container, and a required amount of terephthaldehyde and ammonium persulfate were gradually added and uniformly mixed using a magnetic stirrer. The mixture was continuously stirred to ensure uniform dispersion of terephthaldehyde and ammonium persulfate to obtain a precursor mixture;

[0050] S5, the precursor mixture was transferred to a rotary furnace device for a solidification reaction at a temperature range of 200°C for 1h;

[0051] S6, the obtained material after solidification was transferred to a tube furnace, oxygen was introduced (flow rate of 1000 cubic centimeters / minute), and the temperature was gradually increased to 1400°C for a carbonization reaction for 1h to obtain a hard carbon composite material.

[0052] Comparative Example 1:

[0053] Different from Example 1, no sodium molybdate was added in step S1, and the others were the same as Example 1.

[0054] Comparative Example 2:

[0055] Different from Example 1, no glutaraldehyde and ammonium persulfate were added in step S2, and the others were the same as Example 1.

[0056] Performance test of the materials prepared in the above examples and comparative examples:

[0057] (1) SEM test

[0058] The hard carbon composite material prepared in Example 1 was subjected to SEM test, and the test results are shown in FIG. 1. Figure 1 As can be seen from FIG. 1, the composite material presents a granular structure with slight adhesion, and the particle size D50 is between 5-10μm. Figure 1

[0059] (2) Physicochemical properties and button cell test

[0060] The hard carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to interlayer spacing D002, specific surface area, powder OI value, and powder conductivity determination. The test was performed according to the method of national standard GBT-24533-2019 "Lithium ion battery graphite negative electrode material". The test results are shown in Table 1.

[0061] ​The hard carbon composite materials in Examples 1-3 and Comparative Examples 1-2 were assembled into button cells as lithium ion battery negative electrode materials, and the specific preparation method of the negative electrode material was as follows: mixing the hard carbon composite material: CMC: SBR: SP: H2O in a mass ratio of 94:2.5:1.5:2:150 to obtain a negative electrode sheet; a sodium sheet was used as the counter electrode; NaPF6 (solvent: EC: DEC: PC: propylene glycol polyoxypropylene ether = 1:2:1:0.05, concentration 1.3 mol / L) was used as the electrolyte; and a composite film of polyethylene PE, polypropylene PP and polyethylene propylene PEP was used as the separator. The button cell was assembled in an argon-filled glove box. The electrochemical performance was tested on a Wuhan Lan electric CT2001A battery tester, the charge and discharge voltage range was 0.00V to 2.0V, the charge and discharge rate was 0.1C, the initial discharge capacity and the initial efficiency of the button cell were tested, and the rate performance (1C / 0.1C) was tested. At the same time, the button cell was charged to 100% SOC, and the button cell was disassembled to calculate the full charge expansion. The test results are shown in Table 1.

[0062] Table 1

[0063]

[0064] As can be seen from Table 1, the hard carbon composite material prepared in Examples 1-3 is superior to Comparative Example 1-2 in terms of initial efficiency, initial discharge specific capacity and interlayer spacing D002. The reason is that the material is doped with molybdenum, which relies on the high specific capacity of molybdenum itself to improve the specific capacity of the hard carbon composite material. At the same time, the cross-linking and oxidation of the aldehyde group cross-linking agent with the oxidizing agent forms a large number of chemical groups on the surface of the material, improves the sodium storage function and the initial efficiency of the material, and expands the interlayer spacing of the material by the sodium ions generated in the carbonization process of sodium molybdate, improves the D002 spacing, and improves the rate performance.

[0065] (3) Soft pack battery test:

[0066] The hard carbon composite materials in Examples 1-3 and Comparative Example 1-2 were mixed and coated to prepare negative electrode sheets, and layered oxides (NaFe 1 / 3 Mn 1 / 3 Ni 1 / 3 O2) were used as the positive electrode, NaPF6 (solvent: EC: DEC: PC: propylene glycol polyoxypropylene ether = 1:2:1:0.05, concentration 1.3 mol / L) was used as the electrolyte, and 5Ah soft pack batteries were prepared.

[0067] Test the cycle performance: charge and discharge current 1.0C / 1.0C, voltage range 1-4.0V, cycle number 500 times.

[0068] Test the rate performance: test the initial cycle DCR of the soft pack battery and the constant current ratio under 2C charging condition.

[0069] The test results are shown in Table 2.

[0070] Table 2

[0071] Item Cycling retention (%) 2C constant current ratio (%) DCR (mΩ) Example 1 95.5 94.4 14.45 Example 2 94.1 94.0 15.28 Example 3 95.7 95.3 13.12 Comparative Example 1 92.5 87.8 20.25 Comparative Example 2 91.3 88.5 18.98

[0072] From Table 2, it can be seen that the cycle performance and constant current ratio of Examples 1-3 are obviously superior to those of Comparative Examples 1-2. The reason is that the material of Examples has high specific surface area, which improves the liquid retention performance of the material, and the material is doped with sodium salt, which improves the conduction rate of sodium ions in the material and the large interlayer spacing, which improves the rate performance and reduces the DCR.

[0073] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A bio-asphalt-based composite hard carbon composite material, characterized in that, include: The materials are asphalt, imidazole ionic liquid, amino resin, sodium molybdate, carbon precursor, aldehyde crosslinking agent, and oxidant, with the following mass fractions: 100 parts asphalt, 500-2000 parts imidazole ionic liquid, 100-200 parts amino resin, 1-5 parts sodium molybdate, 10-30 parts aldehyde crosslinking agent, and 1-5 parts oxidant. The method for preparing the bio-asphalt-based composite hard carbon composite material includes the following steps: S1. Prepare the required imidazole ionic liquid as a solvent according to the above ratio, then gradually add the asphalt powder to the imidazole ionic liquid, stir and heat to 50°C until the asphalt is completely dissolved in the imidazole ionic liquid to form a uniform mixed solution. S2. Add the required amount of amino resin and sodium molybdate to the mixed solution in 3-5 portions, stirring the mixture continuously. Heat the reaction system to a temperature range of 100℃-200℃ to ensure uniform dispersion and reaction, and maintain the reaction time for 1-6 hours to allow the reaction to proceed, thus obtaining the reaction mixture. S3. Transfer the reaction mixture onto filter paper for filtration. Transfer the resulting filter residue to a vacuum drying oven and vacuum dry at 80°C for 24 hours to obtain the hard carbon precursor material. S4. Place the hard carbon precursor material into a container, gradually add the required amount of aldehyde crosslinking agent and oxidant, and use a magnetic stir bar to mix evenly. Continue to stir the mixture to ensure that the aldehyde crosslinking agent and oxidant are evenly dispersed with the hard carbon precursor to obtain a precursor mixture. S5. Transfer the precursor mixture to a rotary kiln and cure it for 1-6 hours at a temperature range of 100℃-200℃. S6. After curing, the resulting material is transferred to a tube furnace, oxygen is introduced, and the temperature is gradually raised to 1000℃-1400℃ for carbonization reaction for 1-6 hours to obtain hard carbon composite material.

2. The bio-asphalt-based composite hard carbon composite material according to claim 1, characterized in that: In step S2, the amino resin is one of urea-formaldehyde resin, melamine resin, or benzo-melamine resin, and in step S4, the aldehyde crosslinking agent is one of glutaraldehyde, eicosidine, or terephthalaldehyde.

3. The bio-asphalt-based composite hard carbon composite material according to claim 1, characterized in that: In step S1, the imidazole ionic liquid is one of 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium bromide, 1-propenyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, or 1-propenyl-3-methylimidazolium chloride.

4. The bio-asphalt-based composite hard carbon composite material according to claim 1, characterized in that: In step S4, the oxidant is either ammonium persulfate or sodium persulfate.

5. The bio-asphalt-based composite hard carbon composite material according to claim 1, characterized in that: The stirring in step S1 is done with a magnetic stirrer, the heating in step S2 is done with a heating plate, and the oxygen flow rate in step S6 is usually 100-1000 cubic centimeters per minute.

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