A resin-based coated pitch-based hard carbon composite material and a method for preparing the same

Abstract

The application relates to the technical field of secondary battery material preparation, and discloses a preparation method of a resin-based coated pitch-based hard carbon composite material, which comprises the following steps: S1, uniformly mixing pitch, sodium nitrite, 1,4-p-phenylenediamine and a catalyst, performing a diazotization reaction, and obtaining aminated pitch; S2, uniformly mixing the aminated pitch and an aldehyde solution, adding a graphene oxide solution and a nitrogen source, uniformly mixing again, adding a phenol solution, performing an oxidation-reduction reaction, forming a heteroatom-doped resin-based hard carbon composite shell outside the aminated pitch-based hard carbon, and obtaining a hard carbon precursor material; and S3, carbonizing the hard carbon precursor material to obtain a hard carbon composite material. Through the technical scheme, the problem that the first discharge specific capacity, the compaction density and the fast-charging performance of the hard carbon material cannot be balanced in the prior art is solved, so that the comprehensive performance of the hard carbon material is improved.

Description

Technical Field

[0001] This invention relates to the field of secondary battery material preparation technology, specifically to a resin-based coated pitch-based hard carbon composite material and its preparation method. Background Technology

[0002] The negative electrode material used in sodium-ion batteries is mainly hard carbon material. Hard carbon materials are classified into three main types based on different raw materials: biomass hard carbon, resin-based hard carbon, and coal-based hard carbon. Each type of hard carbon material differs in its precursor, pore-forming temperature, and carbon-based material orientation, resulting in significant differences in specific capacity, compaction density, and charging capability, as well as substantial cost variations. For example, biomass hard carbon material has a moderate specific capacity (300~330 mAh / g) and a moderate compaction density (0.9~1.0 g / cm³). 3 It exhibits high initial efficiency (92%); the resin-based hard carbon material has a high specific capacity (320~360mAh / g) and moderate compaction density (0.95~1.05g / cm³). 3 High initial efficiency (90%); coal-based hard carbon materials have low specific capacity (220~250mAh / g) and high compaction density (1.0~1.1g / cm³). 3 It has low initial efficiency (86~89%), good fast charging, and low cost.

[0003] Sodium-ion batteries require the anode material to achieve a balance between initial discharge specific capacity, compaction density, and fast charging performance, but currently hard carbon materials cannot meet this requirement and have lower overall performance. Summary of the Invention

[0004] This invention proposes a resin-based coated bitumen-based hard carbon composite material and its preparation method, which solves the problem in related technologies that the initial discharge specific capacity, compaction density and fast charging performance of hard carbon materials cannot be balanced, resulting in low overall performance of hard carbon materials.

[0005] The technical solution of the present invention is as follows:

[0006] This invention proposes a method for preparing a resin-based coated bitumen-based hard carbon composite material, comprising the following steps:

[0007] S1. Mix asphalt, sodium nitrite, 1,4-p-phenylenediamine and catalyst evenly, and carry out diazotization reaction to obtain aminated asphalt;

[0008] S2. After mixing the aminated asphalt with the aldehyde solution evenly, add the graphene oxide solution and nitrogen source, mix evenly again, add the phenol solution, and carry out the redox reaction to form a heteroatom-doped resin-based hard carbon composite shell on the aminated asphalt-based hard carbon, thus obtaining the hard carbon precursor material.

[0009] S3. After carbonizing the hard carbon precursor material, a hard carbon composite material is obtained.

[0010] In this invention, to improve the compaction density and initial compaction efficiency of hard carbon materials, a resin-based material is coated onto the surface of an asphalt-based precursor via a phenolic reaction, followed by carbonization to obtain a hard carbon composite material. Furthermore, nitrogen doping of the hard carbon composite material can improve its electronic conductivity and rate performance.

[0011] As a further technical solution, the mass ratio of the asphalt, sodium nitrite, 1,4-p-phenylenediamine and catalyst is 100:20~50:40~80:10~50.

[0012] As a further technical solution, the catalyst is a 70% sulfuric acid aqueous solution.

[0013] As a further technical solution, the mass ratio of the aminated asphalt, aldehyde solution, graphene oxide solution, nitrogen source and phenol solution is 100:50~150:50~200:1~5:5~20.

[0014] As a further technical solution, the aldehyde solution has a mass fraction of 35%.

[0015] As a further technical solution, the mass fraction of the graphene oxide solution is 1% to 5%.

[0016] As a further technical solution, the phenolic solution has a mass fraction of 5%.

[0017] As a further technical solution, the diazotization reaction temperature is 50°C and the diazotization reaction time is 24 hours.

[0018] As a further technical solution, the temperature of the redox reaction is 60~100℃, the pressure of the redox reaction is 1~5Mpa, and the time of the redox reaction is 3~12h.

[0019] As a further technical solution, the carbonization temperature is 1200~1500℃, and the carbonization time is 1~6h.

[0020] As a further technical solution, the aldehyde solution includes one of formaldehyde solution, acetaldehyde solution, propionaldehyde solution, pentanal solution, hexanal solution, and furfural solution.

[0021] As a further technical solution, the phenolic solution includes one of phenol solution, cresol solution, xylenol solution, aminophenol solution, nitrophenol solution, and naphthol solution.

[0022] As a further technical solution, the nitrogen source includes one of urea, melamine, pyrrole, aniline, thiophene, and ammonia water.

[0023] As a further technical solution, S3 involves carbonizing the hard carbon precursor material in a reducing gas atmosphere to obtain a hard carbon composite material.

[0024] As a further technical solution, S3 involves first passing the hard carbon precursor material through an inert gas to remove air, and then carbonizing it in a reducing gas atmosphere to obtain a hard carbon composite material.

[0025] As a further technical solution, the inert gas is argon.

[0026] As a further technical solution, the reducing gas includes one of hydrogen, carbon monoxide, and hydrogen sulfide.

[0027] As a further technical solution, the flow rate of the reducing gas is 100~500 SCCM.

[0028] The present invention also includes the application of a method for preparing a resin-coated pitch-based hard carbon composite material in sodium-ion batteries.

[0029] The working principle and beneficial effects of this invention are as follows:

[0030] 1. This invention involves depositing nitrogen-doped phenolic resin on the surface of aminated bitumen via a phenolic reaction. The amino groups on the surface of the aminated bitumen are chemically bonded to some of the aldehyde groups on the aldehyde surface. Subsequently, the phenolic compounds and aldehyde compounds undergo a phenolic reaction through chemical bonds, resulting in excellent uniform coating properties. This improves the compaction density and electronic conductivity of hard carbon composite materials, significantly different from existing technologies that directly coat hard carbon materials with resin solutions. Simultaneously, the hydroxyl and carboxyl groups on the surface of the aminated bitumen react chemically with the graphene oxide to form -CO-NH-, a structurally stable group, further enhancing the compaction density and electronic conductivity of the hard carbon composite material.

[0031] 2. In this invention, the introduction of a reducing gas to reduce graphene oxide to graphene can further improve the electronic conductivity of hard carbon composite materials, while also reducing defects in hard carbon composite materials and improving the first-pass efficiency. Attached Figure Description

[0032] Figure 1 The image shows the hard carbon composite material in Example 1 under a 2000x electron microscope (SEM). Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] In the following examples and comparative examples,

[0035] Asphalt: Model number WSG-HT886, manufacturer: Shanghai Wanzhao Fine Chemical Co., Ltd.

[0036] Graphene oxide: TNGO, manufactured by Zhongke Times Nano Co., Ltd.

[0037] Graphene: TNRGO, manufactured by Zhongke Times Nano Co., Ltd.

[0038] Water-soluble phenolic resin: CAS: 4261-68-1;

[0039] Concentrated sulfuric acid is a 70% sulfuric acid aqueous solution.

[0040] Example 1

[0041] A method for preparing a resin-based coated bitumen-based hard carbon composite material includes the following steps:

[0042] S1. Mix 100g asphalt, 30g sodium nitrite, 60g 1,4-p-phenylenediamine and 30g concentrated sulfuric acid evenly, and diazotize at 50℃ for 24h to obtain aminated asphalt.

[0043] S2. Add 100g of aminated asphalt to 100g of 35% formaldehyde solution and disperse evenly. Add 100g of 3% graphene oxide solution and 3g of urea, disperse evenly again, add 10g of 5% phenol solution, and transfer to a high-pressure reactor. After oxidation-reduction reaction at 80℃ and 3MPa for 8 hours, filter and vacuum dry the filter residue at 80℃ for 24 hours to obtain hard carbon precursor material.

[0044] S3. Transfer the hard carbon precursor material to a tube furnace, first introduce argon gas to purge the air inside the tube, then introduce hydrogen gas (flow rate 300 SCCM), and carbonize at 1300℃ for 3 hours to obtain the hard carbon composite material.

[0045] Example 2

[0046] A method for preparing a resin-based coated bitumen-based hard carbon composite material includes the following steps:

[0047] S1. Mix 100g asphalt, 20g sodium nitrite, 40g 1,4-p-phenylenediamine and 10g concentrated sulfuric acid evenly, and diazotize at 50℃ for 24h to obtain aminated asphalt.

[0048] S2. Add 100g of aminated asphalt to 50g of 35% formaldehyde solution and disperse evenly. Add 50g of 5% graphene oxide solution and 1g of melamine, disperse evenly again, add 5g of 5% cresol solution, and transfer to a high-pressure reactor. Carry out the redox reaction at 60℃ and 5MPa for 12h. Filter and vacuum dry the filter residue at 80℃ for 24h to obtain hard carbon precursor material.

[0049] S3. Transfer the hard carbon precursor material to a tube furnace, first introduce argon gas to purge the air in the tube, then introduce carbon monoxide (flow rate 100 SCCM), and carbonize at 1200℃ for 6 hours to obtain the hard carbon composite material.

[0050] Example 3

[0051] A method for preparing a resin-based coated bitumen-based hard carbon composite material includes the following steps:

[0052] S1. Mix 100g asphalt, 50g sodium nitrite, 80g 1,4-p-phenylenediamine and 50g concentrated sulfuric acid evenly, and diazotize at 50℃ for 24h to obtain aminated asphalt.

[0053] S2. Add 100g of aminated asphalt to 150g of 35% formaldehyde solution and disperse evenly. Add 200g of 1% graphene oxide solution and 5g of pyrrole, disperse evenly again, add 20g of 5% xylenol solution, and transfer to a high-pressure reactor. Carry out the redox reaction at 100℃ and 1MPa for 3 hours. Filter and vacuum dry the filter residue at 80℃ for 24 hours to obtain hard carbon precursor material.

[0054] S3. Transfer the hard carbon precursor material to a tube furnace, first introduce argon gas to purge the air in the tube, then introduce hydrogen sulfide (flow rate 500 SCCM), and carbonize at 1500℃ for 1 hour to obtain the hard carbon composite material.

[0055] Comparative Example 1

[0056] The only difference between this comparative example and Example 1 is that in S2, the aminated pitch is replaced with an equal amount of pitch, and the graphene oxide is replaced with an equal amount of graphene.

[0057] Comparative Example 2

[0058] The only difference between this comparative example and Example 1 is that in S2, the aminated bitumen was replaced with an equal amount of bitumen.

[0059] Comparative Example 3

[0060] The only difference between this comparative example and Example 1 is that in S2, graphene oxide is replaced with an equal amount of graphene.

[0061] Comparative Example 4

[0062] A method for preparing a resin-based coated bitumen-based hard carbon composite material includes the following steps:

[0063] S1. Mix 100g asphalt, 30g sodium nitrite, 60g 1,4-p-phenylenediamine and 30g concentrated sulfuric acid evenly, and diazotize at 50℃ for 24h to obtain aminated asphalt.

[0064] S2. Add 5g of water-soluble phenolic resin to 100g of deionized water and disperse evenly. Then add 100g of aminated asphalt and ultrasonically disperse evenly at 80℃ for 3h. Filter and vacuum dry the filter residue at 80℃ for 24h. Transfer it to a tube furnace, first introduce argon gas to purge the air in the tube, and then carbonize at 1300℃ for 3h to obtain a hard carbon composite material.

[0065] Performance testing:

[0066] (1) SEM test

[0067] The hard carbon composite material prepared in Example 1 was subjected to SEM testing, and the test results are as follows: Figure 1 As shown, by Figure 1 It can be seen that the hard carbon composite material exhibits a spherical structure with a particle size D50 between 5 and 10 μm.

[0068] (2) Physical and chemical properties and button cell testing

[0069] The interlayer spacing (D002), specific surface area, tap density, and powder conductivity of the hard carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-4 were determined according to the method in GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries". At the same time, the compaction density of the powder was tested under a pressure of 2T using a compaction density meter. The test results are shown in Table 1.

[0070] The hard carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-4 were used as negative electrode materials for sodium-ion batteries to assemble coin cells. The specific preparation method for the negative electrode material was as follows: a negative electrode sheet was prepared by mixing hard carbon composite material, CMC, SBR, SP, and H2O in a mass ratio of 94:2.5:1.5:2:150; a sodium sheet was used as the counter electrode; the electrolyte was NaPF6 (solvent: EC:DEC:PC:propylene glycol polyoxypropylene ether = 1:2:1:0.05, concentration 1.3 mol / L); the separator was a composite membrane of polyethylene (PE), polypropylene (PP), and polyethylene propylene (PEP). The coin cells were assembled in an argon-filled glove box. Electrochemical performance was tested using a Wuhan Landian CT2001A battery tester, with a charge / discharge voltage range of 0-2.0V and a charge / discharge rate of 0.1C. The initial discharge specific capacity and initial efficiency of the coin cells were tested, and the test results are shown in Table 1.

[0071] Table 1. Performance test results of the hard carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-4

[0072]

[0073] As shown in Table 1, the tap density, compaction density, initial discharge specific capacity, initial efficiency, and powder conductivity of the hard carbon composite materials prepared in Examples 1-3 are all higher than those in Comparative Examples 1-4. This indicates that depositing nitrogen-doped phenolic resin on the surface of aminated pitch through phenolic reaction can improve the tap density, compaction density, initial discharge specific capacity, initial efficiency, and powder conductivity of the hard carbon composite material. Furthermore, by using aminated pitch and graphene oxide as raw materials, the chemical reaction characteristics of the chemical groups on the surface of aminated pitch and graphene oxide can be utilized to enhance the bonding force between materials and improve their layered structure, thereby further improving the tap density, compaction density, initial discharge specific capacity, initial efficiency, and powder conductivity of the hard carbon composite material.

[0074] (3) Soft-pack battery test:

[0075] The hard carbon composite materials obtained in Examples 1-3 and Comparative Examples 1-4 were slurried and coated to prepare negative electrode sheets. Layered oxide was used as the positive electrode, and NaPF6 (solvent: EC:DEC:PC:propylene glycol polyoxypropylene ether = 1:2:1:0.05, concentration 1.3mol / L) was used as the electrolyte to prepare a 5Ah soft pack battery.

[0076] Test cycle performance:

[0077] Charge / discharge current 1.0C / 1.0C, voltage range 1~4.0V, cycle count 500 times.

[0078] Rate performance testing: Testing the initial cycle DCR and constant current ratio under 2C charging conditions of the pouch battery.

[0079] The test results are shown in Table 2.

[0080] Table 2. Performance test results of the hard carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-4

[0081]

[0082] As can be seen from Table 2 in this invention, the cycle retention rate and 2C constant current ratio in Examples 1-3 are higher than those in Comparative Examples 1-4. This indicates that depositing nitrogen-doped phenolic resin on the surface of aminated pitch through phenolic reaction can improve the cycle performance and constant current ratio of hard carbon composite materials. Furthermore, by using aminated pitch and graphene oxide as raw materials and utilizing the chemical reaction characteristics of the chemical groups on the surface of aminated pitch and graphene oxide, the cycle performance and constant current ratio of hard carbon composite materials can be further improved.

[0083] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a resin-based coated bitumen-based hard carbon composite material, characterized in that, Includes the following steps: S1. Mix asphalt, sodium nitrite, 1,4-p-phenylenediamine and catalyst evenly, and carry out diazotization reaction to obtain aminated asphalt; S2. After mixing the aminated asphalt with the aldehyde solution evenly, add the graphene oxide solution and nitrogen source, mix evenly again, add the phenol solution, and carry out the redox reaction to form a heteroatom-doped resin-based hard carbon composite shell on the aminated asphalt-based hard carbon, thus obtaining the hard carbon precursor material. S3. After carbonizing the hard carbon precursor material, a hard carbon composite material is obtained. In step S2, the mass ratio of aminated asphalt, aldehyde solution, graphene oxide solution, nitrogen source and phenol solution is 100:50~150:50~200:1~5:5~20; The mass fraction of the graphene oxide solution is 1% to 5%; In step S2, the temperature of the redox reaction is 60~100℃, the pressure of the redox reaction is 1~5MPa, and the time of the redox reaction is 3~12h.

2. The method for preparing a resin-based coated bitumen-based hard carbon composite material according to claim 1, characterized in that, In step S1, the mass ratio of asphalt, sodium nitrite, 1,4-p-phenylenediamine and catalyst is 100:20~50:40~80:10~50.

3. The method for preparing a resin-based coated bitumen-based hard carbon composite material according to claim 1, characterized in that, In step S3, the carbonization temperature is 1200~1500℃ and the carbonization time is 1~6h.

4. The method for preparing a resin-based coated bitumen-based hard carbon composite material according to claim 1, characterized in that, The aldehyde solution includes one of the following: formaldehyde solution, acetaldehyde solution, propionaldehyde solution, pentanal solution, hexanal solution, and furfural solution.

5. The method for preparing a resin-based coated bitumen-based hard carbon composite material according to claim 1, characterized in that, The phenolic solution includes one of the following: phenol solution, cresol solution, xylenol solution, aminophenol solution, nitrophenol solution, and naphthol solution.

6. The method for preparing a resin-based coated bitumen-based hard carbon composite material according to claim 1, characterized in that, Step S3 involves carbonizing the hard carbon precursor material in a reducing gas atmosphere to obtain a hard carbon composite material.

7. The method for preparing a resin-based coated bitumen-based hard carbon composite material according to claim 6, characterized in that, The reducing gas includes one of hydrogen, carbon monoxide, and hydrogen sulfide.

8. The application of the hard carbon composite material prepared by the method for preparing a resin-based coated bitumen-based hard carbon composite material according to any one of claims 1 to 7 in sodium-ion batteries.

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