Energy-saving and long-life carbon crucible and preparation method

Abstract

The present invention relates to the field of lithium battery production technology, and more particularly to an energy-saving and long-life carbon crucible and a preparation method. The energy-saving and long-life carbon crucible is made by high-temperature carbonization of the following raw materials in parts by weight: 10-50 parts of carbon coarse aggregate, 20-35 parts of carbon fine aggregate, 15-40 parts of carbon fine powder, 0.01-3 parts of a tempering additive, and 3-25 parts of a water-soluble binder; the conditioning additive comprises aluminum powder, vanadium powder, vanadium carbide, and benzopyrene. A composite binder and the conditioning additive are mixed with the carbon. During the calcination process, a three-dimensional network structure of C-V2AlC is formed inside the crucible, enhancing corrosion resistance. The coupling effect of in-situ generated carbon fibers and the highly damage-tolerant V2AlC further improves the toughness and thermal shock stability of the product, extending its service life. The tempering additive promotes graphitization of the carbon crucible, improving its high-temperature stability while reducing wettability with the contents, thereby saving energy and reducing emissions and lowering production costs.

Description

Technical Field

[0001] This invention relates to the field of lithium battery production technology, and in particular to an energy-saving and long-life carbon crucible and its preparation method. Background Technology

[0002] With the rapid development of the global new energy industry, unprecedented strong demand has emerged for new energy vehicles, energy storage equipment, and consumer electronics products, leading to a significant increase in demand for carbon anode materials. As a key material for lithium-ion batteries, carbon anode materials have gradually become the mainstream anode material, accounting for approximately 70% of the market share. The carbonization process of artificial carbon anode materials is a crucial factor affecting the quality of anode materials and also a major technical challenge. Currently, domestic carbonization equipment is diverse, energy-intensive, polluting, and has a low degree of automation, which to some extent limits the development of carbon anode materials and is a major problem that urgently needs to be solved in the production of anode materials.

[0003] Currently, the main types of furnaces used in the carbonization process of anode materials include the Atchison carbonization furnace, the internal series carbonization furnace, the box-type carbonization furnace, and the continuous carbonization furnace. Among them, the Atchison carbonization furnace is the most widely used, while the internal series carbonization furnace is used to a lesser extent. The internal series carbonization furnace has the characteristics of high thermal efficiency and short power supply time. When the product is directly heated, the resistance is uniform, and the yield of the product is high.

[0004] However, since the inner furnace crucible also serves as a heating element, the quality requirements for carbon crucibles are relatively high. The dense structure and high thermal conductivity of existing carbon crucibles lead to the consumption of a large amount of precious carbon resources and the problems of rapid crucible cooling and high energy consumption during service. These issues cannot overcome the key technical challenges that need to be addressed for the efficient utilization of carbon resources and environmental protection and energy conservation.

[0005] Therefore, we propose an energy-saving and long-life carbon crucible and its preparation method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing an energy-saving and long-life carbon crucible and its preparation method.

[0007] An energy-saving and long-life carbon crucible is prepared by high-temperature carbonization of the following raw materials in parts by weight:

[0008] 10-50 parts of carbon coarse aggregate, 20-35 parts of carbon fine aggregate, 15-40 parts of carbon fine powder, 0.01-3 parts of conditioning additive, and 3-25 parts of water-soluble binder.

[0009] The modifier is composed of 20-30 parts by weight of aluminum powder, 40-60 parts by weight of vanadium powder, 50-70 parts by weight of vanadium carbide and 10-20 parts by weight of benzo[a]pyrene.

[0010] Preferably, the carbon aggregate includes coarse carbon aggregate and fine carbon aggregate, wherein the carbon aggregate is one or more of low-carbon earthy graphite, conductive carbon black, activated carbon and pitch, the particle size of the coarse carbon aggregate is 1 mm to 3 mm, and the particle size of the fine carbon aggregate is 0.08 mm to 1 mm.

[0011] Preferably, the carbon fine powder is one or more of low-carbon earthy graphite, conductive carbon black, activated carbon, and pitch, and the particle size of the carbon fine powder is 200-600 mesh.

[0012] Preferably, the water-soluble binder is one or more selected from furfural resin, epoxy resin-modified phenolic resin, arabic resin, lignin, polyvinyl alcohol, and phosphate.

[0013] A method for preparing an energy-saving and long-life carbon crucible includes the following steps:

[0014] S1. Add carbon fine powder and conditioning additives to a high-speed mixer and premix for 15 min to 12 h to obtain the batch material;

[0015] S2. The premixed batch material from step S1 is loaded into a high-speed ball mill. 5% to 50% of the batch material mass of deionized water is added to the high-speed ball mill. Then, the mixture is dried and granulated using a high-speed spray granulation device to obtain granulated material.

[0016] S3. Premix carbon aggregate with half of the water-soluble binder at 25℃~200℃ for 15min~12h, add the granulated material prepared in step S2, mix at 25℃~280℃ for 15min~12h, continue to add the remaining half of the water-soluble binder, mix at the same temperature for 15min~12h to obtain a uniform mixture.

[0017] S4. Dry and acclimate the mixture obtained in step S3 to obtain a shaped mixture;

[0018] S5. The mixture obtained in step S4 is placed into an extrusion molding machine to obtain a carbon crucible blank. Then, the ceramic tube blank obtained by extrusion molding is subjected to isostatic pressing to obtain a dense and uniform carbon crucible blank.

[0019] S6. Place the carbon crucible blank obtained in step S5 in a high-temperature furnace and hold it at 200℃~400℃ for 0.5h~2h, and at 800℃~1200℃ for 1h~2h to generate a three-dimensional network structure of C-V2AlC in situ, thus obtaining a carbon crucible.

[0020] Preferably, in step S2, when spray drying granulation is performed, the air temperature of the spray granulator is 150℃~300℃, and the particle size of the granulated material is 0.001mm~1.5mm. Then, the material is sealed and trapped at a temperature of 28℃~32℃ for 12h~36h.

[0021] Preferably, in step S4, the drying conditions for the mixture are: temperature 25℃~350℃, humidity 1%~15%, drying time 2h~25h, and sealing and trapping time 12h~48h.

[0022] Preferably, in step S5, the isostatic pressure is 150-200 MPa.

[0023] Preferably, in step S6, the high-temperature furnace is one of the following: an Atchison carbonization furnace, an internal series carbonization furnace, a box-type carbonization furnace, and a continuous carbonization furnace.

[0024] Preferably, in step S6, carbonization is carried out under the protection of vacuum, nitrogen, buried carbon or argon atmosphere, and the temperature is raised to 200℃ to 400℃ at a heating rate of 5℃ / h to 30℃ / h, and then raised to 800℃ to 1200℃ at a heating rate of 10℃ / h to 60℃ / h.

[0025] The beneficial effects of this invention are:

[0026] 1. A composite binder and modifier are used to mix carbon with the material. During the calcination process, a three-dimensional network structure of C-V2AlC is formed inside the sagger, which fills the pores and forms a chemical bond between the carbon aggregate and the matrix, enhancing the corrosion resistance of the carbon sagger. At the same time, the coupling effect between the carbon fiber generated in situ and V2AlC with high damage tolerance further improves the toughness and thermal shock stability of the product, increasing its service life.

[0027] 2. The added quenching and tempering additives to the carbon crucible promote graphitization, improving its high-temperature stability while reducing its wettability with the contents. The graphitization process continues during product use. These products can accelerate the reduction of carbon emissions in the carbon crucible industry, while simultaneously lowering production costs and enhancing the industry's and the economy's global competitiveness.

[0028] 3. A crucible matrix with controllable microstructure is prepared by using different particle size distributions. A high-solids slurry is mixed by a high-speed ball mill. The components with good dispersibility and large specific gravity differences are not prone to segregation. The dry powder is prepared by slurry spray granulation. In both dry and wet molding, the composition and structure of each part of the product can be guaranteed to be uniform.

[0029] 4. By determining the shape and thickness according to the product's usage requirements, different molding methods are selected, which improves the density of carbon crucibles, enhances the product's comprehensive mechanical properties and thermal shock stability, significantly reduces raw material consumption caused by machining, and greatly increases product profits for manufacturing enterprises. Detailed Implementation

[0030] The present invention will be further explained below with reference to specific embodiments.

[0031] Example 1:

[0032] An energy-saving and long-life carbon crucible is prepared by high-temperature carbonization of the following raw materials in parts by weight:

[0033] 20 parts of activated carbon coarse aggregate with a particle size of 1mm to 3mm, 25 parts of activated carbon fine aggregate with a particle size of 0.08mm to 1mm, 35 parts of activated carbon fine powder with a particle size of 200 to 600 mesh, 1.5 parts of conditioning additives, and 8 parts of furfural resin binder.

[0034] The additive consists of 27 parts by weight of aluminum powder, 51 parts by weight of vanadium powder, 63 parts by weight of vanadium carbide and 12 parts by weight of benzo[a]pyrene.

[0035] A method for preparing an energy-saving and long-life carbon crucible includes the following steps:

[0036] S1. Add activated carbon powder and conditioning additives to a high-speed mixer and premix for 45 minutes to obtain the batch material.

[0037] S2. The premixed batch material from step S1 is loaded into a high-speed ball mill. Deionized water of 40% of the batch material mass is added to the high-speed ball mill. Then, the mixture is dried and granulated using a high-speed spray granulation device. The air temperature of the spray granulator is 220℃. The particle size of the granulated material is 0.8mm. Then, the material is sealed and trapped at 30℃ for 24 hours to obtain the granulated material.

[0038] S3. Premix the activated carbon aggregate with half of the furfural resin binder at 80°C for 30 minutes, add the granulated material prepared in step S2, mix at 100°C for 30 minutes, continue to add the remaining half of the furfural resin binder, and mix at the same temperature for 60 minutes to obtain a uniform mixture.

[0039] S4. The mixture obtained in step S3 is dried at 180°C and 2% humidity for 5 hours, and then sealed and trapped for 36 hours to obtain the shaped mixture.

[0040] S5. The mixture obtained in step S4 is placed into an extrusion molding machine to obtain a carbon crucible blank. Then, the ceramic tube blank obtained by extrusion molding is subjected to isostatic pressing to obtain a dense and uniform carbon crucible blank. The isostatic pressing pressure is 180MPa.

[0041] S6. Place the carbon crucible blank obtained in step S5 into a high-temperature furnace. The high-temperature furnace is an internal series carbonization furnace. Carbonization is carried out under the protection of nitrogen atmosphere, so that a layer of carbon nitride is formed on the surface of the crucible, which improves the crucible's resistance to hydrogen corrosion. The temperature is raised to 300℃ at a heating rate of 20℃ / h and held for 1h. Then the temperature is raised to 1100℃ at a heating rate of 40℃ / h and held for 2h. A three-dimensional network structure of C-V2AlC is generated in situ, and the carbon crucible is obtained.

[0042] Example 2:

[0043] An energy-saving and long-life carbon crucible is prepared by high-temperature carbonization of the following raw materials in parts by weight:

[0044] 30 parts of low-carbon earthy graphite coarse aggregate with a particle size of 1mm to 3mm, 25 parts of low-carbon earthy graphite fine aggregate with a particle size of 0.08mm to 1mm, 25 parts of low-carbon earthy graphite fine powder with a particle size of 200 to 600 mesh, 2 parts of conditioning additive, and 10 parts of epoxy resin modified phenolic resin binder.

[0045] The additive consists of 27 parts by weight of aluminum powder, 51 parts by weight of vanadium powder, 63 parts by weight of vanadium carbide and 12 parts by weight of benzo[a]pyrene.

[0046] A method for preparing an energy-saving and long-life carbon crucible includes the following steps:

[0047] S1. Add low-carbon earthy graphite powder and conditioning additives to a high-speed mixer and premix for 30 minutes to obtain the batch material.

[0048] S2. The premixed batch material from step S1 is loaded into a high-speed ball mill. 30% of the batch material mass of deionized water is added to the high-speed ball mill. Then, the mixture is dried and granulated using a high-speed spray granulation device. The air temperature of the spray granulator is 220℃. The particle size of the granulated material is 0.8mm. The material is then sealed and trapped at 30℃ for 24 hours to obtain the granulated material.

[0049] S3. Premix the low-carbon earthy graphite aggregate with half of the epoxy resin modified phenolic resin binder at 60°C for 30 min, add the granulated material prepared in step S2, mix at 80°C for 30 min, continue to add the remaining half of the epoxy resin modified phenolic resin binder, mix at the same temperature for 60 min, and obtain a uniform mixture.

[0050] S4. The mixture obtained in step S3 is dried at 180°C and 2% humidity for 5 hours, and then sealed and trapped for 36 hours to obtain the shaped mixture.

[0051] S5. The mixture obtained in step S4 is placed into an extrusion molding machine to obtain a carbon crucible blank. Then, the ceramic tube blank obtained by extrusion molding is subjected to isostatic pressing to obtain a dense and uniform carbon crucible blank. The isostatic pressing pressure is 200 MPa.

[0052] S6. Place the carbon crucible blank obtained in step S5 into a high-temperature furnace. The high-temperature furnace is an internal series carbonization furnace. Carbonization is carried out under the protection of nitrogen atmosphere, so that a layer of carbon nitride is formed on the surface of the crucible, which improves the crucible's resistance to hydrogen corrosion. The temperature is raised to 300℃ at a heating rate of 20℃ / h and held for 1h. Then the temperature is raised to 1100℃ at a heating rate of 40℃ / h and held for 2h. A three-dimensional network structure of C-V2AlC is generated in situ, and the carbon crucible is obtained.

[0053] Example 3:

[0054] An energy-saving and long-life carbon crucible is prepared by high-temperature carbonization of the following raw materials in parts by weight:

[0055] 25 parts of conductive carbon black coarse aggregate with a particle size of 1mm to 3mm, 25 parts of conductive carbon black fine aggregate with a particle size of 0.08mm to 1mm, 30 parts of conductive carbon black fine powder with a particle size of 200 to 600 mesh, 2 parts of conditioning additive, and 10 parts of water-soluble binder.

[0056] The additive is composed of 27 parts by weight of aluminum powder, 51 parts by weight of vanadium powder, 63 parts by weight of vanadium carbide and 12 parts by weight of benzo[a]pyrene.

[0057] A method for preparing an energy-saving and long-life carbon crucible includes the following steps:

[0058] S1. Add conductive carbon black fine powder and conditioning additives to a high-speed mixer and premix for 30 minutes to obtain the batch material.

[0059] S2. The premixed batch material from step S1 is loaded into a high-speed ball mill. 35% of the batch material mass of deionized water is added to the high-speed ball mill. Then, the mixture is dried and granulated using a high-speed spray granulation device. The air temperature of the spray granulator is 200℃. The particle size of the granulated material is 0.8mm. Then, the material is sealed and trapped at 30℃ for 24 hours to obtain the granulated material.

[0060] S3. Premix the conductive carbon black aggregate with half of the arabic resin binder at 80°C for 30 minutes, add the granulated material prepared in step S2, mix at 100°C for 30 minutes, continue to add the remaining half of the arabic resin binder, and mix at the same temperature for 60 minutes to obtain a uniform mixture.

[0061] S4. The mixture obtained in step S3 is dried at a temperature of 220℃ and a humidity of 2.5% for 5 hours, and then sealed and trapped for 36 hours to obtain the shaped mixture.

[0062] S5. The mixture obtained in step S4 is placed into an extrusion molding machine to obtain a carbon crucible blank. Then, the ceramic tube blank obtained by extrusion molding is subjected to isostatic pressing to obtain a dense and uniform carbon crucible blank. The isostatic pressing pressure is 200 MPa.

[0063] S6. Place the carbon crucible blank obtained in step S5 into a high-temperature furnace. The high-temperature furnace is an internal series carbonization furnace. Carbonization is carried out under the protection of nitrogen atmosphere, so that a layer of carbon nitride is formed on the surface of the crucible, which improves the crucible's resistance to hydrogen corrosion. The temperature is raised to 350℃ at a heating rate of 25℃ / h and held for 1h. Then the temperature is raised to 1200℃ at a heating rate of 40℃ / h and held for 2h. A three-dimensional network structure of C-V2AlC is generated in situ, and the carbon crucible is obtained.

[0064] Comparative example:

[0065] A carbon crucible is prepared by high-temperature carbonization of the following raw materials in parts by weight:

[0066] 80 parts of activated carbon powder with a particle size of 200-600 mesh and 10 parts of phenolic resin binder.

[0067] Its preparation method includes the following steps:

[0068] S1. Mix high-carbon earth-like graphite powder and phenolic resin binder at 80℃ for 1.5h to obtain a uniform mixture;

[0069] S2. The mixture obtained in step S1 is dried at 200°C and 3% humidity for 5 hours, and then sealed and trapped for 36 hours to obtain the shaped mixture.

[0070] S3. The mixture obtained in step S2 is shaped by friction molding to obtain a carbon crucible blank.

[0071] S6. Place the carbon crucible blank obtained in step S5 into a high-temperature furnace. The high-temperature furnace is a box-type carbonization furnace. The carbonization is carried out under the protection of nitrogen atmosphere. The temperature is raised to 1200℃ at a heating rate of 60℃ / h and held for 2h to obtain the carbon crucible.

[0072] The mechanical properties, thermal shock stability, and wettability of the carbon crucibles used in Examples 1 to 3 and the comparative example were tested. The test results are as follows:

[0073]

[0074] Among them, the compressive strength is the cold compression strength at room temperature, and the testing standard is GB / T1431-2019; the coefficient of thermal expansion is the linear coefficient of thermal expansion between 20℃ and 300℃, and the testing standard is YS / T 63.4-2006; the thermal shock cracking test is the residual strength retention rate after water cooling at 1000℃, and the testing standard is YB 4018-91; the wettability test is conducted under a protective atmosphere, during the heating process from room temperature to 900℃, using a CCD camera to observe the relationship between the changes of the corroded material on the crucible surface and temperature.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An energy-saving and long-life carbon crucible, characterized in that, It is prepared by high-temperature carbonization of the following raw materials in parts by weight: 10-50 parts of carbon coarse aggregate, 20-35 parts of carbon fine aggregate, 15-40 parts of carbon fine powder, 0.01-3 parts of conditioning additive, and 3-25 parts of water-soluble binder. The modifier is composed of 20-30 parts by weight of aluminum powder, 40-60 parts by weight of vanadium powder, 50-70 parts by weight of vanadium carbide and 10-20 parts by weight of benzo[a]pyrene.

2. The energy-saving and long-life carbon crucible according to claim 1, characterized in that, Carbon aggregates include coarse carbon aggregates and fine carbon aggregates. The carbon aggregates are one or more of low-carbon earthy graphite, conductive carbon black, activated carbon, and pitch. The particle size of the coarse carbon aggregates is 1 mm to 3 mm, and the particle size of the fine carbon aggregates is 0.08 mm to 1 mm.

3. The energy-saving and long-life carbon crucible according to claim 1, characterized in that, The carbon fine powder is one or more of low-carbon earthy graphite, conductive carbon black, activated carbon, and pitch, and the particle size of the carbon fine powder is 200-600 mesh.

4. The energy-saving and long-life carbon crucible according to claim 1, characterized in that, The water-soluble binder is one or more of furfural resin, epoxy resin-modified phenolic resin, arabic resin, lignin, polyvinyl alcohol, and phosphate.

5. A method for preparing an energy-saving and long-life carbon crucible, characterized in that, Includes the following steps: S1. Add the carbon fine powder and conditioning additives described in claim 1 to a high-speed mixer and premix for 15 min to 12 h to obtain the compound material; S2. The premixed batch material from step S1 is loaded into a high-speed ball mill. 5% to 50% of the batch material mass of deionized water is added to the high-speed ball mill. Then, the mixture is dried and granulated using a high-speed spray granulation device to obtain granulated material. S3. The carbon aggregate described in claim 1 is premixed with half of the water-soluble binder at 25°C to 200°C for 15 min to 12 h. The granulated material prepared in step S2 is added and mixed at 25°C to 280°C for 15 min to 12 h. The remaining half of the water-soluble binder is added and mixed at the same temperature for 15 min to 12 h to obtain a uniform mixture. S4. Dry and acclimate the mixture obtained in step S3 to obtain a shaped mixture; S5. The mixture obtained in step S4 is placed into an extrusion molding machine to obtain a carbon crucible blank. Then, the ceramic tube blank obtained by extrusion molding is subjected to isostatic pressing to obtain a dense and uniform carbon crucible blank. S6. Place the carbon crucible blank obtained in step S5 in a high-temperature furnace and hold it at 200℃~400℃ for 0.5h~2h, and at 800℃~1200℃ for 1h~2h to generate a three-dimensional network structure of C-V2AlC in situ, thus obtaining a carbon crucible.

6. The method for preparing an energy-saving and long-life carbon crucible according to claim 5, characterized in that, In step S2, when spray drying granulation is carried out, the air temperature of the spray granulator is 150℃~300℃, and the particle size of the granulated material is 0.001mm~1.5mm. Then, the material is sealed and trapped at a temperature of 28℃~32℃ for 12h~36h.

7. The method for preparing an energy-saving and long-life carbon crucible according to claim 5, characterized in that, In step S4, the drying conditions for the mixture are: temperature 25℃~350℃, humidity 1%~15%, drying time 2h~25h, and sealing and trapping time 12h~48h.

8. The method for preparing an energy-saving and long-life carbon crucible according to claim 5, characterized in that, In step S5, the isostatic pressure is 150–200 MPa.

9. The method for preparing an energy-saving and long-life carbon crucible according to claim 5, characterized in that, In step S6, the high-temperature furnace is one of the following: Atchison carbonization furnace, internal string carbonization furnace, box-type carbonization furnace, and continuous carbonization furnace.

10. The method for preparing an energy-saving and long-life carbon crucible according to claim 5, characterized in that, In step S6, carbonization is carried out under the protection of vacuum, nitrogen, buried carbon, or argon atmosphere, with the temperature increased to 200℃ to 400℃ at a heating rate of 5℃ / h to 30℃ / h, and then increased to 800℃ to 1200℃ at a heating rate of 10℃ / h to 60℃ / h.