Composite binder, preparation process of artificial graphite, artificial graphite and application

Abstract

The invention provides a composite binder, a preparation process of artificial graphite, the artificial graphite and application. The composite binder comprises a component A, a component B and a component C, the component A comprises a soft carbon binder, the component B comprises a hard carbon binder, and the component C comprises a cross-linking agent. The soft carbon binder meets a relational expression I or a relational expression II, the residual carbon content of the component A is a, the residual carbon content of the component B is b, a + b is less than or equal to 2.90%, a / (a + b) is more than or equal to 60%, and the mass ratio of the component C to the component A is less than or equal to 20%. According to the composite binder, binders with certain parameters and contents are selected to be combined, and a certain crosslinking agent is supplemented, so that block spallation caused by falling, rolling, extrusion and collision in the furnace entering process can be avoided, the integrity of the block structure is ensured, the easy depolymerization property of the graphitized block can be ensured, and the service life of the graphitized block is prolonged. The damage of strong depolymerization to the surface appearance of the graphite is prevented, so that the problem of low initial coulombic efficiency of the artificial graphite can be improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, in particular to the field of material synthesis technology for secondary batteries, and more particularly to a composite binder, a preparation process of artificial graphite, artificial graphite and applications. Background Art

[0002] Artificial graphite is currently the most widely used negative electrode material. It is generally made from needle coke or petroleum coke and is a powder material prepared through processes such as crushing, shaping, granulation, graphitization, and coating carbonization.

[0003] Graphitization is one of the core processes in the preparation of artificial graphite. At present, the graphitization process mainly uses an intermittent graphitization furnace, which heats the resistor material / graphite plate / crucible products with electricity, and then heat-treats the coke raw material powder to achieve structural evolution and finally form graphite. Since the graphitization process requires insulation materials, resistor materials, graphite crucibles, graphite box plates and other auxiliary materials, a large amount of energy is consumed to heat these auxiliary materials, resulting in a low thermal energy utilization rate of the intermittent graphitization furnace (~50%). In addition, due to the differences in temperature field distribution, the degree of graphitization of materials at different locations (furnace head / furnace tail, upper layer / lower layer) is different, which weakens the consistency of graphitized product indicators.

[0004] Compared with intermittent graphitization furnaces, continuous graphitization furnaces have higher thermal energy utilization (no auxiliary materials are required), shorter production cycles, ultra-low manufacturing costs, and less smoke emissions. The residence time of the material in the high-temperature zone can be accurately controlled by adjusting the furnace entry and exit processes, thereby significantly improving the consistency of the graphitized products. However, the material is usually a micron-sized powder, and directly entering the continuous graphitization furnace can easily cause material leakage, furnace spraying, and clogging at the discharge port. Therefore, a binder is needed to bond the powder into particles. On the one hand, there are gaps between the particles, and the exhaust gas generated during the heat treatment process can escape through the gaps, avoiding the occurrence of furnace spraying and making material discharge smoother; on the other hand, the material processing capacity of a single furnace is also increased.

[0005] The use of adhesives in the continuous graphitization process can ensure that the carbonized blocks maintain their structural integrity before entering the graphitization furnace and in the furnace stage, and prevent the carbonized blocks from disintegrating and spreading. After graphitization, the graphite blocks will disperse on their own or through a micro-deagglomeration process, a graphite product with high particle size consistency, moderate specific gravity, and regular morphology can be obtained. However, the requirements for adhesives for blocks entering the furnace and blocks leaving the furnace are contradictory to some extent: if the structural strength of the blocks entering the furnace is too high, the graphitized blocks leaving the furnace usually need to increase the deagglomeration strength to obtain powders with high particle size consistency. However, high deagglomeration strength will lead to deterioration of particle morphology, increase of specific gravity, and reduction of initial efficiency. If the graphitized blocks leaving the furnace show excessive ease of deagglomeration, the structural strength of the blocks entering the furnace will be greatly weakened, and particles will disintegrate and spread in the early stage of graphitization, causing blockage and even the risk of furnace spraying.

[0006] Therefore, how to rationally design the adhesive components and structure to meet the very different performance requirements of the blocks entering the furnace and the blocks leaving the furnace to obtain graphitized products with better performance is of great significance for improving the performance of graphitized products. Summary of the Invention

[0007] Based on the above problems, the present invention provides a composite binder, a preparation process for artificial graphite, artificial graphite, and its application. The composite binder is a combination of binders with specific parameters and contents, supplemented with a certain cross-linking agent. This can not only prevent the block from breaking apart due to falling, tumbling, squeezing, and collision during the furnace entry process, ensuring the integrity of the block structure, but also ensure the easy depolymerization of the graphitized block, preventing strong depolymerization from damaging the graphite surface morphology. Therefore, the low initial coulombic efficiency of artificial graphite can be improved, and a graphite negative electrode material with indicators and performance that meet the requirements can be obtained.

[0008] To achieve the above-mentioned purpose, the first aspect of the present invention provides a composite binder for preparing artificial graphite by continuous graphitization of a graphite precursor. The composite binder includes component A, component B and component C. The component A includes a soft carbon binder, the component B includes a hard carbon binder, and the component C includes a crosslinking agent. The soft carbon binder satisfies equation 1 or equation 2, the residual carbon content of the component A is a, the residual carbon content of the component B is b, a+b≤2.90%, a / (a+b)≥60%, and the mass ratio of the component C to the component A is ≤20%. T SP is the temperature at which the soft carbon binder changes from solid to molten liquid, T IFT The temperature corresponding to the contact angle of 90° between the soft carbon binder and the base coke raw material is obtained when the soft carbon binder infiltrates the base coke raw material. The residual carbon amount is the product of the coking value and the mass proportion of the residual carbon in the graphite precursor.

[0009] (T IFT -T SP ) / T SP ≤0.30T SP ≤150℃ Relationship 1

[0010] (T IFT -T SP ) / T SP ≤0.12T SP >150℃ Relationship 2

[0011] The composite binder of the present invention includes a soft carbon binder, a hard carbon binder and a crosslinking agent with certain parameters and contents. Component A that satisfies equation 1 or equation 2 is selected, and a soft carbon binder with a certain coking value is selected and its content is controlled (i.e., it has a certain residual carbon amount) to give it high affinity. The soft carbon binder has good graphitization ability and better affinity with graphite precursors. It can also play a structural support role at high temperatures and has a certain modification effect on the graphite surface. However, in the medium and low temperature range of 200 to 400°C, internal molecules dissolve, the viscosity decreases, and the structural support function is significantly weakened. However, the addition of a hard carbon binder can make up for this defect. Compared with soft carbon binders, hard carbon binders are more difficult to graphitize and have a more significant bonding effect on particles. They can play a structural support role in medium and low temperatures between 200 and 400°C. However, the structural support role is weakened after high-temperature heat treatment, and too much hard carbon binder will reduce the first coulomb efficiency of the material. Therefore, controlling a / (a+b) ≥ 60% so that the content of component B is low can not only compensate for the problems of soft carbon binders in the medium and low temperature range but also avoid the negative effects brought about by high temperature and high content. In addition, a small amount of crosslinking agent is added to the soft carbon binder and the hard carbon binder. The crosslinking agent can induce a crosslinking reaction in the soft carbon binder molecules, increase the viscosity of the system, strengthen the structural stability, shorten the low viscosity temperature window, accelerate the solidification and molding, and avoid the melting and softening of the soft carbon binder and the collapse of the structure. Therefore, under the action of the crosslinking agent, a+b is controlled to be ≤2.90%. The use of components A and B with low residual carbon content can meet the strength requirements of continuous graphitization, and the low residual carbon content can improve the easy depolymerization performance of the graphitized product, thereby meeting the different requirements of the continuous graphitization furnace block and the furnace block for the adhesive. In short, the present invention can ensure that the composite adhesive has a stable structure in the medium and low temperature range and the high temperature range by selecting a composite adhesive including a soft carbon binder, a hard carbon binder and a crosslinking agent with certain parameters and contents, and at the same time has better easy depolymerization performance, which can avoid the problem of poor performance of the artificial graphite produced due to different requirements of the continuous graphitization furnace block and the furnace block for the adhesive.

[0012] As a technical solution of the present invention, the soft carbon binder is selected from at least one of oil-based asphalt, coal-based asphalt, impregnated asphalt, modified asphalt and high softening point asphalt.

[0013] As a technical solution of the present invention, the hard carbon binder is selected from at least one of phenolic resin, epoxy resin, coumarone resin, biomass oil, cassava flour and water-soluble starch.

[0014] As a technical solution of the present invention, the cross-linking agent is selected from at least one of terephthalic alcohol, benzaldehyde, p-tolualdehyde, p-phenylenediamine, p-toluenesulfonic acid, sulfur, N-bromosuccinimide and N-iodosuccinimide.

[0015] As a technical solution of the present invention, the B component also includes a polymer adhesive, and the polymer adhesive is selected from at least one of polyacrylic acid, styrene-butadiene-styrene block copolymer, ethylene-octene copolymer, ethylene-ethyl acrylate copolymer, styrene-ethylene / butylene-styrene triblock copolymer, ethylene-octene copolymer, chloroprene rubber, ethylene-ethyl acrylate copolymer, sodium carboxymethyl cellulose, polyvinylidene fluoride and polyethylene terephthalate.

[0016] As a technical solution of the present invention, the T SP Obtained using Mettler DP70 test.

[0017] As a technical solution of the present invention, the T IFT Obtained through testing using the Dataphysics OCA20 measuring instrument.

[0018] A second aspect of the present invention provides a process for preparing artificial graphite, comprising the steps of:

[0019] (1) Selection of binder for graphitization

[0020] The adhesive is the aforementioned composite adhesive;

[0021] (2) Mixing

[0022] Mixing the graphite precursor, the component A, the component B, the component C and a solvent to obtain a mixture;

[0023] (3) Molding, drying and carbonization

[0024] The mixture is pressed into balls, dried and carbonized in sequence to obtain a carbonized body, and the anti-pulverization factor of the carbonized body is η 碳化 , 50kPa≤η 碳化 ≤90kPa;

[0025] (4) Continuous graphitization

[0026] The carbonized body is graphitized to obtain a graphitized body, wherein the anti-pulverization factor of the graphitized body is η 石墨化 , 20kPa≤η 石墨化 ≤36kPa;

[0027] (5) Post-processing

[0028] The graphitized body is post-processed.

[0029] In the preparation method of the present invention, a composite binder of a soft carbon binder, a hard carbon binder and a cross-linking agent with certain parameters and contents is used for carbonization and graphitization, and a powdering resistance factor η can be obtained before graphitization. 碳化 The carbide is 50 to 90, with high η 碳化 It can ensure the structural integrity of the block before entering the graphitization furnace and in the initial stage of entering the furnace, as well as the safety of the graphitization furnace. Due to the low residual carbon content design of the composite binder, the powdering resistance factor η is obtained after graphitization treatment. 石墨化 Graphitized body with a value of 20 to 36, low η 石墨化 The graphitized body can have better deagglomeration performance, so through the micro-deagglomeration process, a graphite material with high particle size consistency and regular morphology can be obtained, thereby improving the problem of low initial coulombic efficiency of the graphitized product and obtaining a graphite material with indicators and performance that meet the requirements.

[0030] As a technical solution of the present invention, the graphite precursor is selected from at least one of needle green coke, calcined needle coke, petroleum green coke, calcined petroleum coke and isotropic coke.

[0031] As a technical solution of the present invention, the particle size Dv50 of the graphite precursor is 6 to 25 μm.

[0032] As a technical solution of the present invention, the solvent is selected from at least one of water, ethanol, isopropanol, toluene, tetrahydrofuran, N-methyl-2-pyrrolidone, n-heptane, n-hexane, cyclohexane, acetone and N,N-dimethylformamide.

[0033] As a technical solution of the present invention, the solvent accounts for 7 to 25% of the mass of the mixed material.

[0034] As a technical solution of the present invention, the carbide is a sphere, an ellipsoid or a cylinder.

[0035] As a technical solution of the present invention, the carbide body is a cylinder with a diameter of 8 to 40 mm and a height h of 8 to 30 mm.

[0036] As a technical solution of the present invention, the powder resistance factor after drying is η 烘干 , 120kPa≤η 烘干 ≤145kPa.

[0037] As a technical solution of the present invention, the equipment used for mixing is selected from a glass reactor, a stainless steel reactor, a double planetary mixer, a kneader, a VC mixer, a fusion machine or a three-dimensional mixer.

[0038] As a technical solution of the present invention, the pressing method is selected from molding, roller extrusion, rotary rolling or extrusion molding.

[0039] As a technical solution of the present invention, the drying temperature is 70 to 350° C. and the drying time is 2 to 15 hours.

[0040] As a technical solution of the present invention, the carbonization temperature is 900-1250° C. and the time is 3-15 hours.

[0041] As a technical solution of the present invention, the post-processing includes depolymerization, and the depolymerization is performed using a depolymerizer, and the main engine frequency of the depolymerizer is 10 to 25 Hz.

[0042] As a technical solution of the present invention, the graphitization treatment is performed using a continuous graphitization furnace.

[0043] As a technical solution of the present invention, the temperature of the continuous graphitization furnace is 2600-3200° C., and the time is 2-10 hours.

[0044] A third aspect of the present invention provides artificial graphite prepared by the aforementioned process for preparing artificial graphite.

[0045] As a technical solution of the present invention, the particle size Dv50 of the artificial graphite is 7 to 25 μm.

[0046] As a technical solution of the present invention, the specific surface area of ​​the artificial graphite is 0.5 to 2.5 m 2 / g.

[0047] As a technical solution of the present invention, the gram capacity of the artificial graphite is 320 to 355 mAh / g.

[0048] As a technical solution of the present invention, the first coulombic efficiency of the artificial graphite is ≥93.2%.

[0049] A fourth aspect of the present invention provides artificial graphite prepared by the aforementioned process for preparing artificial graphite or use of the aforementioned artificial graphite in a battery.

[0050] A fifth aspect of the present invention is a secondary battery comprising a positive electrode material, a negative electrode material and an electrolyte, wherein the negative electrode material comprises artificial graphite prepared by the aforementioned process for preparing artificial graphite or the aforementioned artificial graphite. DETAILED DESCRIPTION

[0051] The artificial graphite of the present invention is used as the negative electrode material of the battery, and can be used alone or mixed with other negative electrode active materials (such as natural graphite, silicon material, silicon-carbon material, silicon-oxygen material, soft carbon and / or hard carbon, etc.).

[0052] Artificial graphite can be used in secondary batteries, which include positive electrode materials, negative electrode materials and electrolytes.

[0053] The positive electrode material includes at least one of a lithium cobalt oxide positive electrode material, a lithium iron phosphate positive electrode material, a lithium nickel cobalt manganese oxide positive electrode material, and a lithium nickel cobalt aluminum oxide positive electrode material. The lithium cobalt oxide positive electrode material may be lithium cobalt oxide, or doped or coated lithium cobalt oxide. The lithium iron phosphate positive electrode material may be lithium iron phosphate, or doped or coated lithium iron phosphate. The lithium nickel cobalt manganese oxide positive electrode material may be lithium nickel cobalt manganese oxide, or doped or coated lithium nickel cobalt manganese oxide. The lithium nickel cobalt aluminum oxide positive electrode material may be lithium nickel cobalt aluminum oxide, or doped or coated lithium nickel cobalt aluminum oxide.

[0054] The electrolyte includes an electrolyte salt, a non-aqueous organic solvent, and an additive. The electrolyte salt may be, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethylsulfonate (LiCF3SO3), lithium bis(oxalatoborate) (C4BLiO8), lithium difluorooxalatoborate (C2BF2LiO4), lithium difluorophosphate (LiPO2F2), and lithium difluorobis(oxalatophosphate) (LiDFBP). The non-aqueous organic solvent is selected from carbonates and / or carboxylates. Furthermore, the non-aqueous organic solvent is selected from at least one of ethylene carbonate (PC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, and butyl propionate. The additive may be vinylene carbonate (VC), fluoroethylene carbonate (FEC), diethylene sulfate (DTD), 1,3-propene sultone (PST), or methylene methyl disulfonate (MMDS).

[0055] The particle size Dv50 of the artificial graphite of the present invention is 7 to 25 μm. For example, Dv50 can be, but is not limited to, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, 19 μm, 20 μm, 21 μm, 23 μm, and 25 μm. The specific surface area of ​​the artificial graphite is 0.5 to 2.5 m 2 / g, as an example, the specific surface area can be but is not limited to 0.5m 2 / g, 0.8m 2 / g, 1.0m 2 / g, 1.3m 2 / g, 1.5m 2 / g, 1.8m 2 / g, 2.0m 2 / g, 2.2m 2 / g, 2.5m 2 / g. The gram capacity of artificial graphite is 320-355 mAh / g. For example, the gram capacity can be, but is not limited to, 320 mAh / g, 325 mAh / g, 330 mAh / g, 335 mAh / g, 340 mAh / g, 345 mAh / g, 350 mAh / g, and 355 mAh / g. The first coulombic efficiency of artificial graphite is ≥92.5%. For example, the first coulombic efficiency can be, but is not limited to, 92.5%, 93.0%, 93.5%, 94.0%, 94.5%, 95.0%, 95.5%, and 96.0%.

[0056] The preparation process of the artificial graphite of the present invention may include the following steps: (1) selecting a binder for graphitization; (2) mixing; (3) forming, drying and carbonizing; (4) continuous graphitization; and (5) post-processing.

[0057] In step (1), a graphitization binder is selected, which may be a composite binder. The composite binder may include component A, component B, and component C.

[0058] Component A includes a soft carbon binder, which is selected from at least one of oil-based asphalt, coal-based asphalt, impregnated asphalt, modified asphalt, and high-softening-point asphalt. The soft carbon binder is selected from such materials and satisfies equation 1 or equation 2. SP T is the temperature at which the soft carbon binder changes from solid to molten liquid, measured using Mettler DP70. IFT The temperature corresponding to the contact angle of 90° when the soft carbon binder infiltrates the base coke raw material is measured using a Dataphysics OCA20 measuring instrument.

[0059] (T IFT -T SP ) / T SP ≤0.30T SP ≤150℃ Relationship 1

[0060] (T IFT -T SP ) / T SP ≤0.12T SP >150℃ Relationship 2

[0061] Component B includes a hard carbon binder selected from at least one of phenolic resin, epoxy resin, coumarone resin, biomass oil, tapioca flour, and water-soluble starch. Furthermore, component B also includes a polymer binder selected from at least one of polyacrylic acid, styrene-butadiene-styrene block copolymer, ethylene-octene copolymer, ethylene-ethyl acrylate copolymer, styrene-ethylene / butylene-styrene triblock copolymer, ethylene-octene copolymer, chloroprene rubber, ethylene-ethyl acrylate copolymer, sodium carboxymethyl cellulose, polyvinylidene fluoride, and polyethylene terephthalate.

[0062] To ensure a stable structure in both the low and high temperature ranges during the graphitization process, soft carbon binders, hard carbon binders, and polymer binders with specific coking values ​​are selected, while their mass percentages in the graphite precursor are controlled. This is known as the residual carbon content (the product of the coking value and the mass percentage in the graphite precursor). The residual carbon content of component A is a, and the residual carbon content of component B is b. Where a+b ≤ 2.90% and a / (a+b) ≥ 60%, the ratio of the hard carbon binder to the polymer binder in component B can be determined based on actual conditions, as long as a+b ≤ 2.90% and a / (a+b) ≥ 60% are satisfied. Furthermore, a+b may be, but is not limited to, 2.90%, 2.85%, 2.80%, 2.75%, 2.70%, 2.65%, 2.60%, 2.55%, 2.50%, 2.45%, 2.40%, 2.35%, 2.30%, 2.25%, 2.20%, 2.15%, 2.10%, 2.05%, or 2.00%. a / (a+b) may be, but is not limited to, 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80%, 83%, 85%, 88%, or 90%.

[0063] Component C includes a crosslinking agent selected from at least one of p-terephthalic alcohol, benzaldehyde, p-tolualdehyde, p-phenylenediamine, p-toluenesulfonic acid, sulfur, N-bromosuccinimide, and N-iodosuccinimide. Component C accounts for ≤20% of Component A by weight. For example, the proportion of Component C may be, but is not limited to, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, or 10%.

[0064] Step (2) mixing includes mixing the graphite precursor, component A, component B, component C, and solvent to obtain a mixture. During operation, component A, component B, and component C can be mixed separately, such as mixing the graphite precursor, component A, and component C to obtain a primary mixture, and then mixing the primary mixture, component B, and solvent to obtain a mixture. Alternatively, the graphite precursor and component A are first mixed to obtain a primary mixture, and then the primary mixture, component B, component C, and solvent are mixed to obtain a mixture.

[0065] The graphite precursor is selected from at least one of needle green coke, calcined needle coke, petroleum green coke, calcined petroleum coke, and isotropic coke. The graphite precursor has a particle size (Dv50) of 6 to 25 μm. For example, the Dv50 can be, but is not limited to, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, and 25 μm. The solvent is selected from at least one of water, ethanol, isopropanol, toluene, tetrahydrofuran, N-methyl-2-pyrrolidone, n-heptane, n-hexane, cyclohexane, acetone, and N,N-dimethylformamide. The solvent accounts for 7 to 25% of the mixture by weight. For example, the solvent proportion can be, but is not limited to, 7%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, and 25%. The equipment used for mixing is selected from glass reactor, stainless steel reactor, double planetary mixer, kneader, VC mixer, fusion machine or three-dimensional mixer;

[0066] Step (3) forming, drying and carbonizing includes pressing the mixture into balls, drying and carbonizing to obtain a carbonized body, and the powdering resistance factor of the carbonized body is η 碳化 , 50kPa≤η 碳化 ≤90kPa,η 碳化 It can be, but is not limited to, 50kPa, 55kPa, 60kPa, 65kPa, 70kPa, 75kPa, 80kPa, 85kPa, and 90kPa. The powdering resistance factor after drying is η 烘干 , 120kPa≤η 烘干 ≤145kPa, η 烘干The pressure may be, but is not limited to, 120 kPa, 125 kPa, 130 kPa, 135 kPa, 140 kPa, or 145 kPa. The pressing method is selected from molding, roller extrusion, rotary rolling, or extrusion molding. The drying temperature is 70 to 350 ° C. For example, the temperature may be, but is not limited to, 70 ° C, 100 ° C, 150 ° C, 200 ° C, 250 ° C, 300 ° C, or 350 ° C. The drying time is 2 to 15 hours. For example, the time may be, but is not limited to, 2 hours, 5 hours, 8 hours, 10 hours, 12 hours, 14 hours, or 15 hours. The carbonization temperature is 900 to 1250 ° C. For example, the temperature may be, but is not limited to, 900 ° C, 950 ° C, 1000 ° C, 1050 ° C, 1100 ° C, 1150 ° C, 1200 ° C, or 1250 ° C. The time is 3 to 15 hours. For example, the time can be, but is not limited to, 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, 11 hours, 13 hours, or 15 hours. The carbide is a sphere, an ellipsoid, or a cylinder. If the carbide is a cylinder, the diameter is 8 to 40 mm and the height h is 8 to 30 mm.

[0067] Step (4) continuous graphitization includes graphitizing the carbonized body to obtain a graphitized body, and the pulverization resistance factor of the graphitized body is η 石墨化 , 20kPa≤η 石墨化 ≤36kPa.η 石墨化 The pressure may be, but is not limited to, 20 kPa, 22 kPa, 24 kPa, 26 kPa, 28 kPa, 30 kPa, 32 kPa, 34 kPa, or 36 kPa. The graphitization treatment is performed in a continuous graphitization furnace at a temperature of 2600 to 3200°C. For example, the temperature may be, but is not limited to, 2600°C, 2650°C, 2700°C, 2750°C, 2800°C, 2850°C, 2900°C, 2950°C, 3000°C, 3050°C, 3100°C, 3150°C, or 3200°C. The treatment time is 2 to 10 hours. For example, the treatment time may be, but is not limited to, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0068] Step (5) post-processing includes post-processing the graphitized body, and the post-processing includes depolymerization. The depolymerization is performed using a depolymerizer. The main frequency of the depolymerizer is 10 to 25 Hz. Since the graphitized body has good depolymerization properties, the depolymerization can be performed using a low frequency.

[0069] Among them, if the carbide is a sphere or ellipsoid, the powdering resistance factor η=P cs *(D1-D2) / D1, P cs =a*F / (π*D2 2), D1 is the diameter of the sphere, μm, D2 is the diameter corresponding to the maximum pressure value of the sphere, μm, F is the maximum pressure value that the sphere can withstand, mN, and a is the collapse coefficient.

[0070] The test process for the powdering resistance factor η can be as follows: press the mixture into a sphere with a diameter of about 20 mm, and then make a sphere sample. Use a caliper to measure the diameter D1 (μm) of the sphere sample, preheat the universal material testing machine and clean the sample table surface, ensure that the pressure sensor reading is zero, then place the sphere sample on the sample table, gradually apply static pressure, and record the stress-strain curve to obtain the maximum pressure value F (mN) that the sphere sample can withstand and the corresponding sphere size D2 (μm). Based on the formula P cs =a*F / (π*D2 2 ) to obtain the compressive strength P of the sphere cs (kPa), where a is the collapse coefficient, which is generally 2.48×10 6 , according to P cs Further calculation yields the powder resistance factor η=P cs *(D1-D2) / D1. If the anti-powdering factor is η 烘干 , the mixture is pressed into spheres and then dried and hardened to form sphere samples. 碳化 , the mixture is pressed into spheres, and then dried, hardened, and carbonized to prepare sphere samples. 石墨化 The mixture is pressed into spheres, then dried, hardened, carbonized, and graphitized to prepare the spherical samples. The pressing, drying, carbonization, and graphitization processes for the pulverization resistance factor η test can be compared to those for artificial graphite, but the sample shape must remain essentially unchanged during the test.

[0071] If the carbide is cylindrical, the powdering resistance factor η=P cs *(H1-H2) / H1,P cs =a*F / (π*D 2 ), D is the cylinder's diameter, μm, H1 is the cylinder's height, μm, H2 is the height at which the cylinder withstands maximum pressure, μm, F is the maximum pressure the cylinder withstands, mN, and a is the collapse coefficient. The test procedure for the powdering resistance factor η is similar to that for a sphere, but static pressure is applied in the height direction of the cylinder.

[0072] In order to better illustrate the purpose, technical solutions and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0073] Example 1

[0074] This embodiment is a process for preparing artificial graphite, which includes the following steps.

[0075] (1) Selection of binder for graphitization

[0076] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, (T IFT -T SP ) / T SP =0.04. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0077] (2) Mixing

[0078] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%), oil-based asphalt, p-terephthalate, and p-toluenesulfonic acid were mixed in a VC (V / V) mixture to produce a primary mix. The oil-based asphalt was added in an amount of 3.04 wt.% (compared to calcined petroleum coke), resulting in a carbon residue of 1.75% in component A. The amounts of p-terephthalate and p-toluenesulfonic acid introduced were 0.304 wt.% and 0.051 wt.%, respectively (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then added to a kneader and kneaded to produce a mixture. The kneader speed was 35 Hz, the kneading time was 2 h, the amount of thermosetting phenolic resin added was 2.65 wt.% (compared to calcined petroleum coke), and the amount of PAA solution added was 0.56 wt.% (compared to calcined petroleum coke). Therefore, the residual carbon content of component B was 1.02%, and water accounted for 8.7% of the total mass of the mixture.

[0079] (3) Molding, drying and carbonization

[0080] The mixture was extruded into balls to obtain balls with a diameter of 19.2 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 180 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonization resistance factor η of the carbide is 132.1kPa, and then carbonized at 1150℃ for 6h to obtain a carbide. 碳化 It is 82.6kPa and the diameter is 18.7mm.

[0081] (4) Continuous graphitization

[0082] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was石墨化 It is 31.3kPa.

[0083] (5) Post-processing

[0084] The graphite body is depolymerized in a depolymerizer with a main frequency of 19 Hz and controlled by D V 50 is 11.0±1.5μm, and artificial graphite is obtained.

[0085] Example 2

[0086] (1) Selection of binder for graphitization

[0087] The adhesive includes component A, component B and component C. Component A is T SP The coking value of modified asphalt below 150℃ is 60.7%. IFT -T SP ) / T SP =0.24. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA aqueous solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0088] (2) Mixing

[0089] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%), modified asphalt, p-terephthalate, and p-toluenesulfonic acid were mixed in a VC (V / V) mixture to produce a primary mix. The modified asphalt was added in an amount of 2.88 wt.% (compared to calcined petroleum coke), resulting in a carbon residue in component A of 1.75%. The amounts of p-terephthalate and p-toluenesulfonic acid introduced were 0.288 wt.% and 0.048 wt.%, respectively (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then added to a kneader and kneaded to produce a mixture. The kneader speed was 35 Hz, the kneading time was 2 h, the amount of thermosetting phenolic resin added was 2.65 wt.% (compared to calcined petroleum coke), and the amount of PAA solution added was 0.56 wt.% (compared to calcined petroleum coke). Therefore, the residual carbon content of component B was 1.02%, and water accounted for 9.3% of the total mass of the mixture.

[0090] (3) Molding, drying and carbonization

[0091] The mixture was extruded into balls to obtain balls with a diameter of 20.8 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 170 ° C and maintained for 4 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonization resistance factor η of the carbide is 128.3kPa, and then carbonized at 1150℃ for 6h to obtain a carbide. 碳化It is 78.3kPa and the diameter is 20.3mm.

[0092] (4) Continuous graphitization

[0093] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 28.2kPa.

[0094] (5) Post-processing

[0095] The graphite is depolymerized in a depolymerizer with a main frequency of 17 Hz and controlled by D V 50 is 11.0±1.5μm, and artificial graphite is obtained.

[0096] Example 3

[0097] This embodiment is a process for preparing artificial graphite, which includes the following steps.

[0098] (1) Selection of binder for graphitization

[0099] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, (T IFT -T SP ) / T SP =0.04. Component B contains epoxy resin and sodium carboxymethyl cellulose powder, the epoxy resin has a coking value of 39.2%, and the sodium carboxymethyl cellulose powder has a coking value of 21.2%. Component C includes p-methylbenzaldehyde and p-toluenesulfonic acid.

[0100] (2) Mixing

[0101] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%) and oil-based asphalt were mixed to produce a primary mix. The oil-based asphalt was added in an amount of 2.86 wt.% (compared to the calcined petroleum coke), resulting in a 1.65% residual carbon content in component A. The primary mix, p-methylbenzaldehyde, p-toluenesulfonic acid, epoxy resin, sodium carboxymethylcellulose powder, ethanol, and water were then placed in a blender and kneaded to produce a mixture. Among them, the speed of the fusion machine is 150rpm, the fusion time is 30min, the introduction amounts of p-tolualdehyde and p-toluenesulfonic acid are 0.372% and 0.149% respectively (compared with calcined petroleum coke), the addition amount of epoxy resin is 2.68wt.% (compared with calcined petroleum coke), and the addition amount of sodium carboxymethyl cellulose powder is 0.16wt.% (compared with calcined petroleum coke). Therefore, the residual carbon content of component B is 1.08%, and ethanol and water (volume ratio of 1:9) account for 15.3% of the total mass of the mixture.

[0102] (3) Molding, drying and carbonization

[0103] The mixture was molded into a cylinder with a diameter of 19.3 mm and a height of 17.8 mm. The pressed cylinder was heat treated at 75 ° C for 10 h, and then heated to 220 ° C and maintained for 4 h to obtain a dried cylinder. The powdering resistance factor η of the dried cylinder was 烘干 The carbonization resistance factor η of the carbide is 136.4 kPa, and then carbonized at 950 ° C for 4 hours to obtain a carbide. 碳化 It is 65.5kPa and the diameter is 17.2mm.

[0104] (4) Continuous graphitization

[0105] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 25.3kPa.

[0106] (5) Post-processing

[0107] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 16 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0108] Example 4

[0109] This embodiment is a process for preparing artificial graphite, which includes the following steps.

[0110] (1) Selection of binder for graphitization

[0111] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 73.2%. IFT -T SP ) / T SP =0.08. Component B contains thermosetting phenolic resin and PVDF powder, the coking value of the thermosetting phenolic resin is 37.7%, and the coking value of the PVDF powder is 34.6%. Component C is sulfur.

[0112] (2) Mixing

[0113] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%), oil-based asphalt, and sulfur were mixed in a VC mixture to produce a primary mix. The oil-based asphalt was added in an amount of 2.53 wt.% (compared to calcined petroleum coke), resulting in a carbon residue of 1.85% in component A. The sulfur was introduced in an amount of 0.177 wt.% (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PVDF powder, N-methylpyrrolidone, and water were then placed in a kneader and kneaded to produce a mixture. Among them, the speed of the kneader is 40 Hz, the kneading time is 2.5 h, the addition amount of thermosetting phenolic resin is 2.26 wt.% (compared to calcined petroleum coke), and the addition amount of PVDF powder is 0.087 wt.% (compared to calcined petroleum coke). Therefore, the residual carbon content of component B is 0.88%, and N-methylpyrrolidone and water (volume ratio of 3:2) account for 18.6% of the total mass of the mixture.

[0114] (3) Molding, drying and carbonization

[0115] The mixture was extruded into balls to obtain balls with a diameter of 20.5 mm. The pressed balls were heat treated at 80 ° C for 6 h, and then heated to 265 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonization resistance factor η of the carbide is 123.7kPa, and then carbonized at 1150℃ for 5h to obtain a carbide. 碳化 It is 85.3kPa and the diameter is 20.0mm.

[0116] (4) Continuous graphitization

[0117] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 35.8kPa.

[0118] (5) Post-processing

[0119] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 23 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0120] Example 5

[0121] This embodiment is a process for preparing artificial graphite, which includes the following steps.

[0122] (1) Selection of binder for graphitization

[0123] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, (T IFT -T SP) / T SP =0.04. Component B comprises a thermosetting phenolic resin and chloroprene rubber, wherein the char value of the thermosetting phenolic resin is 37.7%, and the solid content of the chloroprene rubber is 30% and the char value is 18.9%. Component C is N-bromosuccinimide.

[0124] (2) Mixing

[0125] Calcined petroleum coke (Dv50 of 11.5±1.5 μm, volatile matter≤1.5%) and oil-based asphalt were mixed to obtain a premix. The addition of the oil-based asphalt was 2.60 wt.% (compared to the calcined petroleum coke), resulting in a carbon residue of 1.50% in component A. The premix, N-bromosuccinimide, a thermosetting phenolic resin, chloroprene rubber, and water were then placed in a kneader and mixed to obtain a mixture. The kneader was operated at 35 Hz for 2 hours. The amount of N-bromosuccinimide introduced was 0.26 wt.% (compared to the calcined petroleum coke), the addition of the thermosetting phenolic resin was 2.39 wt.% (compared to the calcined petroleum coke), and the addition of the chloroprene rubber was 1.41 wt.% (compared to the calcined petroleum coke), resulting in a carbon residue of 0.98% in component B. Water accounted for 20.6% of the total mass of the mixture.

[0126] (3) Molding, drying and carbonization

[0127] The mixture was extruded into balls to obtain balls with a diameter of 18.3 mm. The pressed balls were heat treated at 95 ° C for 2 h, and then heated to 235 ° C and maintained for 2 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonization resistance factor η of the carbide is 125.4 kPa, and then carbonized at 1150 ° C for 5 hours to obtain a carbide. 碳化 It is 57.6kPa and the diameter is 17.7mm.

[0128] (4) Continuous graphitization

[0129] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 22.4kPa.

[0130] (5) Post-processing

[0131] The graphite is depolymerized in a depolymerizer with a main frequency of 12 Hz and controlled by D V 50 is 11.0±1.5μm, and artificial graphite is obtained.

[0132] Example 6

[0133] This embodiment is a process for preparing artificial graphite, which includes the following steps.

[0134] (1) Selection of binder for graphitization

[0135] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, (T IFT -T SP ) / T SP =0.04. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA aqueous solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0136] (2) Mixing

[0137] Needle coke (Dv50: 9.5±1.5 μm, volatile matter: 5.3%), oil-based asphalt, p-terephthalic acid, and p-toluenesulfonic acid were mixed to form a primary mix. The oil-based asphalt was added in an amount of 3.04 wt.% (compared to the needle coke), resulting in a carbon residue of 1.75% in component A. The amounts of p-terephthalic acid and p-toluenesulfonic acid introduced were 0.304 wt.% and 0.051 wt.%, respectively (compared to the needle coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then placed in a kneader and kneaded to form a mixture. Among them, the kneader speed is 35 Hz, the kneading time is 2 hours, the addition amount of thermosetting phenolic resin is 2.65 wt.% (compared to needle-shaped coke), the addition amount of PAA solution is 0.56 wt.% (compared to needle-shaped coke), so the residual carbon content of component B is 1.04%, and water accounts for 8.7% of the total mass of the mixture.

[0138] (3) Molding, drying and carbonization

[0139] The mixture was extruded into balls to obtain balls with a diameter of 19.2 mm. The pressed balls were heat treated at 120 ° C for 5 h, and then heated to 180 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonization resistance factor η of the carbide is 125.3kPa, and then carbonized at 1150℃ for 6h to obtain a carbide. 碳化 It is 77.8kPa and the diameter is 18.7mm.

[0140] (4) Continuous graphitization

[0141] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750°C for 4 hours to obtain a graphitized body. The powdering resistance factor η of the graphitized body was 石墨化 It is 26.7kPa.

[0142] (5) Post-processing

[0143] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 17 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0144] Example 7

[0145] (1) Selection of binder for graphitization

[0146] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, (T IFT -T SP ) / T SP =0.04. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA aqueous solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0147] (2) Mixing

[0148] Calcined petroleum coke (Dv50: 18.0±1.5μm, volatile matter ≤1.0%), oil-based asphalt, p-terephthalate, and p-toluenesulfonic acid were mixed in a VC (V / V) mixture to produce a primary mix. The oil-based asphalt was added in an amount of 3.04 wt.% (compared to calcined petroleum coke), resulting in a carbon residue of 1.75% in component A. The amounts of p-terephthalate and p-toluenesulfonic acid introduced were 0.304 wt.% and 0.051 wt.%, respectively (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then placed in a kneader and kneaded to produce a mixture. The kneader speed was 35 Hz, the kneading time was 2 h, the amount of thermosetting phenolic resin added was 2.65 wt.% (compared to calcined petroleum coke), the amount of PAA solution added was 0.56 wt.% (compared to calcined petroleum coke), so the residual carbon content of component B was 1.04%, and water accounted for 18.0% of the total mass of the mixture.

[0149] (3) Molding, drying and carbonization

[0150] The mixture was extruded into balls to obtain balls with a diameter of 19.2 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 180 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 is 130.7 kPa, and then carbonized at 1150 ° C for 5 h to obtain a carbide. The powdering resistance factor η of the carbide is 碳化 It is 79.4kPa and the diameter is 18.7mm.

[0151] (4) Continuous graphitization

[0152] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 6 h to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 28.5kPa.

[0153] (5) Post-processing

[0154] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 18 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0155] Example 8

[0156] This embodiment is a process for preparing artificial graphite, which includes the following steps.

[0157] (1) Selection of binder for graphitization

[0158] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, (T IFT -T SP ) / T SP =0.04. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA aqueous solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0159] (2) Mixing

[0160] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%), oil-based asphalt, p-terephthalate, and p-toluenesulfonic acid were mixed in a VC (V / V) mixture to produce a primary mix. The oil-based asphalt was added in an amount of 3.04 wt.% (compared to calcined petroleum coke), resulting in a carbon residue of 1.75% in component A. The amounts of p-terephthalate and p-toluenesulfonic acid introduced were 0.304 wt.% and 0.051 wt.%, respectively (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then added to a kneader and kneaded to produce a mixture. The kneader speed was 35 Hz, the kneading time was 2 h, the amount of thermosetting phenolic resin added was 2.65 wt.% (compared to calcined petroleum coke), and the amount of PAA solution added was 0.56 wt.% (compared to calcined petroleum coke). Therefore, the residual carbon content of component B was 1.02%, and water accounted for 8.7% of the total mass of the mixture.

[0161] (3) Molding, drying and carbonization

[0162] The mixture was extruded into balls to obtain balls with a diameter of 19.2 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 180 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonized body is 131.8 kPa, and then carbonized at 1150 ° C for 6 hours to obtain the carbide. The powdering resistance factor η of the carbide is 碳化 It is 81.8kPa and the diameter is 18.6mm.

[0163] (4) Continuous graphitization

[0164] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2650°C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 29.8kPa.

[0165] (5) Post-processing

[0166] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 19 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0167] Example 9

[0168] This embodiment is a process for preparing artificial graphite, which includes the following steps.

[0169] (1) Selection of binder for graphitization

[0170] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, (T IFT -T SP ) / T SP ==0.04. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA aqueous solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0171] (2) Mixing

[0172] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%), oil-based asphalt, p-terephthalate, and p-toluenesulfonic acid were mixed in a VC (V / V) mixture to produce a primary mix. The oil-based asphalt was added in an amount of 3.04 wt.% (compared to calcined petroleum coke), resulting in a carbon residue of 1.75% in component A. The amounts of p-terephthalate and p-toluenesulfonic acid introduced were 0.304 wt.% and 0.051 wt.%, respectively (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then added to a kneader and kneaded to produce a mixture. The kneader speed was 35 Hz, the kneading time was 2 h, the amount of thermosetting phenolic resin added was 2.65 wt.% (compared to calcined petroleum coke), and the amount of PAA solution added was 0.56 wt.% (compared to calcined petroleum coke). Therefore, the residual carbon content of component B was 1.04%, and water accounted for 8.7% of the total mass of the mixture.

[0173] (3) Molding, drying and carbonization

[0174] The mixture was extruded into balls to obtain balls with a diameter of 19.2 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 180 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonization resistance factor η of the carbide is 132.5kPa, and then carbonized at 1150℃ for 6h to obtain a carbide. 碳化 It is 83.7kPa and the diameter is 18.8mm.

[0175] (4) Continuous graphitization

[0176] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2850 ° C for 4 h to obtain a graphitized body. The powdering resistance factor η of the graphitized body was 石墨化 It is 33.5kPa.

[0177] (5) Post-processing

[0178] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 21 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0179] Comparative Example 1

[0180] This comparative example is a process for preparing artificial graphite, which includes the following steps.

[0181] Calcined petroleum coke (Dv50 of 11.5±1.5μm, volatile matter ≤1.5%) was placed in a graphite crucible and put into a continuous graphitization furnace for graphitization treatment at a temperature of 2750°C for 4 hours to obtain artificial graphite.

[0182] Comparative Example 2

[0183] This comparative example is a process for preparing artificial graphite, which includes the following steps.

[0184] (1) Selection of binder for graphitization

[0185] The adhesive includes component A and component B. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, ((T IFT -T SP ) / T SP Component B comprises a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, and the PAA aqueous solution has a solid content of 40%, a molecular weight of 400,000, and a coking value of 7.2%.

[0186] (2) Mixing

[0187] Calcined petroleum coke (Dv50: 11.5±1.5μm, volatile matter ≤1.5%) and oil-based asphalt were mixed in a VC mixture to obtain a primary mixture. The oil-based asphalt was added in an amount of 3.04wt.% (compared to the calcined petroleum coke), resulting in a carbon residue of 1.75% in component A. The primary mixture, a thermosetting phenolic resin, a PAA solution, and water were then added to a kneader and kneaded to obtain a mixture. The kneader speed was 35Hz, the kneading time was 2h, the thermosetting phenolic resin was added in an amount of 2.65wt.% (compared to the calcined petroleum coke), and the PAA solution was added in an amount of 0.56wt.% (compared to the calcined petroleum coke). Therefore, the carbon residue of component B was 1.02%, and water accounted for 8.7% of the total mass of the mixture.

[0188] (3) Molding, drying and carbonization

[0189] The mixture was extruded into balls to obtain balls with a diameter of 19.2 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 180 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonized body is 118.4 kPa, and then carbonized at 1150 ° C for 6 hours to obtain the carbide. The powdering resistance factor of the carbide is η 碳化 It is 65.4kPa and the diameter is 18.7mm.

[0190] (4) Continuous graphitization

[0191] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 24.8kPa.

[0192] (5) Post-processing

[0193] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 22 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0194] Comparative Example 3

[0195] This comparative example is a process for preparing artificial graphite, which includes the following steps.

[0196] (1) Selection of binder for graphitization

[0197] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 72.5%, (T IFT -T SP ) / T SP =0.20. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA aqueous solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0198] (2) Mixing

[0199] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%), oil-based asphalt, p-terephthalate, and p-toluenesulfonic acid were mixed in a VC (V / V) mixture to produce a primary mix. The oil-based asphalt was added in an amount of 2.41 wt.% (compared to calcined petroleum coke), resulting in a carbon residue of 1.75% in component A. The amounts of p-terephthalate and p-toluenesulfonic acid introduced were 0.289% and 0.058%, respectively (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then placed in a kneader and kneaded to produce a mixture. The kneader speed was 35 Hz, the kneading time was 2 h, the amount of thermosetting phenolic resin added was 2.65 wt.% (compared to calcined petroleum coke), and the amount of PAA solution added was 0.56 wt.% (compared to calcined petroleum coke). Therefore, the residual carbon content of component B was 1.02%, and water accounted for 8.7% of the total mass of the mixture.

[0200] (3) Molding, drying and carbonization

[0201] The mixture was extruded into balls to obtain balls with a diameter of 19.2 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 180 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonization resistance factor η of the carbide is 134.2kPa, and then carbonized at 1150℃ for 6h to obtain a carbide. 碳化 It is 76.7kPa and the diameter is 18.7mm.

[0202] (4) Continuous graphitization

[0203] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 27.1kPa.

[0204] (5) Post-processing

[0205] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 22 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0206] Comparative Example 4

[0207] This comparative example is a process for preparing artificial graphite, which includes the following steps.

[0208] (1) Selection of binder for graphitization

[0209] The adhesive includes component A, component B and component C. Component A is T SP The coking value of modified asphalt below 150℃ is 55.3%, (T IFT -T SP ) / T SP ==0.65. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0210] (2) Mixing

[0211] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%), modified asphalt, p-terephthalate, and p-toluenesulfonic acid were mixed in a VC (V / V) mixture to produce a primary mix. The modified asphalt was added in an amount of 3.16 wt.% (compared to calcined petroleum coke), resulting in a carbon residue in component A of 1.75%. The amounts of p-terephthalate and p-toluenesulfonic acid introduced were 0.288 wt.% and 0.048 wt.%, respectively (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then added to a kneader and kneaded to produce a mixture. The kneader speed was 35 Hz, the kneading time was 2 h, the amount of thermosetting phenolic resin added was 2.65 wt.% (compared to calcined petroleum coke), and the amount of PAA solution added was 0.56 wt.% (compared to calcined petroleum coke). Therefore, the residual carbon content of component B was 1.02%, and water accounted for 9.3% of the total mass of the mixture.

[0212] (3) Molding, drying and carbonization

[0213] The mixture was extruded into balls to obtain balls with a diameter of 20.8 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 170 ° C and maintained for 4 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonized body is 126.5kPa, and then carbonized at 1150℃ for 6h to obtain the carbide. The powdering resistance factor η of the carbide is 碳化 It is 75.4kPa and the diameter is 20.3mm.

[0214] (4) Continuous graphitization

[0215] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 26.2kPa.

[0216] (5) Post-processing

[0217] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 17 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0218] Comparative Example 5

[0219] This comparative example is a process for preparing artificial graphite, which includes the following steps.

[0220] (1) Selection of binder for graphitization

[0221] The adhesive includes component A, component B and component C. Component A is T SP The coking value of oil-based asphalt above 150℃ is 57.6%, (T IFT -T SP ) / T SP =0.04. Component B contains a thermosetting phenolic resin and a PAA solution. The thermosetting phenolic resin has a coking value of 37.7%, while the PAA solution has a solids content of 40%, a molecular weight of 400,000, and a coking value of 7.2%. Component C includes p-phenylenediol and p-toluenesulfonic acid.

[0222] (2) Mixing

[0223] Calcined petroleum coke (Dv50: 11.5±1.5 μm, volatile matter ≤1.5%), oil-based asphalt, p-terephthalate, and p-toluenesulfonic acid were mixed in a VC (V / V) mixture to produce a primary mix. The oil-based asphalt was added in an amount of 4.34 wt.% (compared to calcined petroleum coke), resulting in a carbon residue of 2.50% in component A. The amounts of p-terephthalate and p-toluenesulfonic acid introduced were 0.304 wt.% and 0.051 wt.%, respectively (compared to calcined petroleum coke). The primary mix, thermosetting phenolic resin, PAA solution, and water were then placed in a kneader and kneaded to produce a mixture. The kneader speed was 35 Hz, the kneading time was 2 h, the amount of thermosetting phenolic resin added was 5.30 wt.% (compared to calcined petroleum coke), and the amount of PAA solution added was 0.694 wt.% (compared to calcined petroleum coke). Therefore, the residual carbon content of component B was 2.02%, and water accounted for 8.7% of the total mass of the mixture.

[0224] (3) Molding, drying and carbonization

[0225] The mixture was extruded into balls to obtain balls with a diameter of 19.2 mm. The pressed balls were heat treated at 85 ° C for 8 h, and then heated to 180 ° C and maintained for 3 h to obtain dried balls. The powdering resistance factor η of the dried balls was 烘干 The carbonization resistance factor η of the carbide is 148.5kPa, and then carbonized at 1150℃ for 6h to obtain a carbide. 碳化 It is 93.2kPa and the diameter is 18.7mm.

[0226] (4) Continuous graphitization

[0227] The carbonized body was put into a continuous graphitization furnace for graphitization treatment at a graphitization temperature of 2750 ° C for 4 hours to obtain a graphitized body. The anti-pulverization factor η of the graphitized body was 石墨化 It is 63.7kPa.

[0228] (5) Post-processing

[0229] The graphitized body was depolymerized in a depolymerizer with a main engine frequency of 28 Hz and the DV50 was controlled to be 11.0±1.5 μm to obtain artificial graphite.

[0230] The artificial graphites prepared in Examples 1 to 9 and Comparative Examples 1 to 5 were tested for physical and electrochemical properties. The test conditions were as follows. The test results are shown in Table 1.

[0231] (1) Physical properties

[0232] The specific surface area was measured using a specific surface area meter.

[0233] The tap density (tap density) was obtained by using a tap density meter.

[0234] The degree of graphitization was calculated from the interlayer spacing d002 according to Franklin's formula.

[0235] (2) Gram capacity performance test

[0236] The artificial graphite prepared in Examples 1 to 9 and Comparative Examples 1 to 5 was used as the active material, mixed with an aqueous dispersion of a binder acrylonitrile multipolymer (LA132, solid content 15%) and a conductive agent (Super-P) in a mass ratio of 92:6:2, and a certain amount of water was added as a solvent for homogenization. The solid content of the slurry was adjusted to 55%, coated on a copper foil, and vacuum dried and rolled to prepare a negative electrode sheet. The counter electrode was a metallic lithium sheet, the electrolyte was a 1 mol / L LiPF6 solution (the solvent was a mixture of EC, DMC, and EMC in a volume ratio of 1:1:1), and the diaphragm was a polypropylene microporous membrane. The cells were assembled into button cells in a glove box filled with inert gas. The charge and discharge tests of the button cells were carried out on the LANHE battery test system of Blue Electric Electronics Co., Ltd. Under room temperature conditions, the battery was discharged at a constant current of 0.1C to a voltage of 0.01V, then discharged at a constant current of 0.02C to a voltage of 0.005V, and charged at a constant current of 0.1C to a voltage of 1.5V to obtain the first reversible capacity (first effect) and first coulombic efficiency.

[0237] Table 1 Performance test results of artificial graphite prepared in Examples 1 to 9 and Comparative Examples 1 to 5

[0238]

[0239] From the results in Table 1, it can be seen that in Examples 1 to 9, by continuously graphitizing a composite binder including a soft carbon binder, a hard carbon binder and a cross-linking agent with certain parameters and contents, artificial graphite with excellent performance can be obtained, especially the first coulomb efficiency is significantly improved.

[0240] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite binder for preparing artificial graphite by continuous graphitization of a graphite precursor, characterized in that: The invention comprises a component A, a component B and a component C, wherein the component A comprises a soft carbon binder, the component B comprises a hard carbon binder, the component C comprises a crosslinking agent, the soft carbon binder satisfies equation 1 or equation 2, the residual carbon content of the component A is a, the residual carbon content of the component B is b, a+b≤2.90%, a / (a+b)≥60%, the mass ratio of the component C to the component A is ≤20%, and T SP is the temperature at which the soft carbon binder changes from solid to molten liquid, T IFT is the temperature corresponding to the contact angle of 90° when the soft carbon binder infiltrates the base coke raw material. The residual carbon amount is the product of the coking value and the mass proportion in the graphite precursor. (T IFT -T SP ) / T SP ≤0.30T SP ≤150℃ Relationship 1 (T IFT -T SP ) / T SP ≤0.12T SP >150℃ Relationship 2.

2. The composite adhesive according to claim 1, characterized in that Includes at least one of the following features ① to ⑥: ① The soft carbon binder is selected from at least one of oil-based asphalt, coal-based asphalt, impregnated asphalt, modified asphalt and high softening point asphalt; ② The hard carbon binder is at least one selected from phenolic resin, epoxy resin, coumarone resin, biomass oil, tapioca flour and water-soluble starch; ③ The cross-linking agent is selected from at least one of terephthalic acid, benzaldehyde, p-tolualdehyde, p-phenylenediamine, p-toluenesulfonic acid, sulfur, N-bromosuccinimide and N-iodosuccinimide; ④ The B component further comprises a polymer binder, which is selected from at least one of polyacrylic acid, styrene-butadiene-styrene block copolymer, ethylene-octene copolymer, ethylene-ethyl acrylate copolymer, styrene-ethylene / butylene-styrene triblock copolymer, ethylene-octene copolymer, chloroprene rubber, ethylene-ethyl acrylate copolymer, sodium carboxymethyl cellulose, polyvinylidene fluoride and polyethylene terephthalate; ⑤T SP Obtained using Mettler DP70 test; ⑥T IFT Obtained through testing using the Dataphysics OCA20 measuring instrument.

3. A process for preparing artificial graphite, characterized in that: Including steps: (1) Selection of binder for graphitization The adhesive is the composite adhesive according to claim 1 or 2; (2) Mixing Mixing the graphite precursor, the component A, the component B, the component C and a solvent to obtain a mixture; (3) Molding, drying and carbonization The mixture is pressed into balls, dried and carbonized in sequence to obtain a carbonized body, and the anti-pulverization factor of the carbonized body is η 碳化 , 50kPa≤η 碳化 ≤90kPa; (4) Continuous graphitization The carbonized body is graphitized to obtain a graphitized body, wherein the anti-pulverization factor of the graphitized body is η 石墨化 , 20kPa≤η 石墨化 ≤36kPa; (5) Post-processing The graphitized body is post-processed.

4. The process for preparing artificial graphite according to claim 3, wherein: At least one of the following features (1) to (12): (1) The graphite precursor is selected from at least one of needle green coke, calcined needle coke, petroleum green coke, calcined petroleum coke and isotropic coke; (2) The particle size Dv50 of the graphite precursor is 6 to 25 μm; (3) The solvent is selected from at least one of water, ethanol, isopropanol, toluene, tetrahydrofuran, N-methyl-2-pyrrolidone, n-heptane, n-hexane, cyclohexane, acetone and N,N-dimethylformamide; (4) the solvent accounts for 7 to 25% of the mass of the mixture; (5) The carbonized body is a sphere, an ellipsoid or a cylinder; (6) The carbide body is cylindrical with a diameter of 8 to 40 mm and a height h of 8 to 30 mm; (7) The powdering resistance factor after drying is η 烘干 , 120kPa≤η 烘干 ≤145kPa; (8) The equipment used for mixing is selected from a glass reactor, a stainless steel reactor, a double planetary mixer, a kneading machine, a VC mixer, a fusion machine or a three-dimensional mixer; (9) The pressing method is selected from molding, roller extrusion, rotary rolling or extrusion molding; (10) The drying temperature is 70 to 350° C. and the drying time is 2 to 15 hours; (11) The carbonization temperature is 900-1250° C. and the time is 3-15 hours; (12) The post-processing includes depolymerization, and the depolymerization is performed using a depolymerization machine, and the main frequency of the depolymerization machine is 10 to 25 Hz.

5. The process for preparing artificial graphite according to claim 3, wherein: The graphitization treatment is performed using a continuous graphitization furnace.

6. The process for preparing artificial graphite according to claim 5, wherein: The temperature of the continuous graphitization furnace is 2600-3200° C., and the time is 2-10 hours.

7. The artificial graphite prepared by the process for preparing artificial graphite according to any one of claims 3 to 6, characterized in that: At least one of the following characteristics (1) to (4): (1) The particle size Dv50 of the artificial graphite is 7 to 25 μm; (2) The specific surface area of ​​the artificial graphite is 0.5 to 2.5 m 2 / g; (3) The gram capacity of the artificial graphite is 320 to 355 mAh / g; (4) The initial coulombic efficiency of the artificial graphite is ≥92.5%.

8. Use of the artificial graphite prepared by the process for preparing artificial graphite according to any one of claims 3 to 6 or the artificial graphite according to claim 7 in batteries.

9. A secondary battery comprising a positive electrode material, a negative electrode material and an electrolyte, characterized in that: The negative electrode material includes artificial graphite prepared by the process for preparing artificial graphite according to any one of claims 3 to 6 or the artificial graphite according to claim 7.

Images