Highly resistant crucible for graphitization of lithium battery negative electrode material and preparation process thereof

Abstract

The application relates to the field of crucibles, in particular to a high-resistance crucible for graphitization of lithium battery negative materials and a preparation process thereof. First, isocyanate-terminated prepolymer is synthesized from hydroxyl-terminated polydimethylsiloxane and isophorone diisocyanate as raw materials under the catalysis of a catalyst dibutyltin dilaurate, and then organic silicon polyurethane prepolymer is synthesized from adipic acid dihydrazide and 4,4'-diamino diphenyl disulfide as chain extenders; further, modified pitch is prepared by in-situ polymerization of the organic silicon polyurethane prepolymer together with composite basalt fiber and cage polyol; polyhydroxyl cage polyol is prepared from polycaprolactone triol, polycaprolactone tetrol and dicyclohexylmethane diisocyanate; and zirconium-titanium bimetallic organic framework with terephthalic acid as an organic ligand is grown on the surface of activated basalt fiber layer by layer through a layer-by-layer self-assembly method, and the composite basalt fiber is obtained by modification treatment with the cage polyol.

Description

Technical Field

[0001] This invention relates to the field of crucibles, specifically a high-durability crucible for graphitization of lithium battery anode materials and its preparation process. Background Technology

[0002] With the advancement of technology, the large-scale application of lithium batteries in power, energy storage and other fields has driven the rapid development of high-temperature graphitization treatment of lithium battery anode carbon materials. As the performance of lithium batteries improves, the degree of graphitization required for their anode carbon materials is higher. The high-temperature graphitization treatment temperature of carbon materials is generally 2600-3000℃ to ensure the purity requirements of carbon materials for lithium battery anodes. At the same time, high temperature can cause oxidation and inconsistent thermal expansion of graphite crucibles during use, leading to cracks.

[0003] The average service life of crucibles used for high-temperature graphitization of carbon materials in the current market is 5 cycles. The short service life and the tendency to crack during use make it important to improve the durability of crucibles. Summary of the Invention

[0004] The purpose of this invention is to provide a high-resistance crucible for graphitization of lithium battery anode materials and its preparation process, so as to solve the problems in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A process for preparing a high-resistance crucible for graphitization of lithium battery anode materials includes the following steps:

[0007] S1: Graphitized petroleum coke is crushed, ground, and sieved to obtain graphitized petroleum coke skeleton material and graphitized petroleum coke powder.

[0008] S2: Mix graphitized petroleum coke skeleton material, graphitized petroleum coke powder, and modified asphalt to obtain a mixture.

[0009] S3: The mixed materials are sequentially molded, calcined, and processed to obtain a high-resistant crucible for graphitization of lithium battery anode materials.

[0010] Furthermore, the particle size of the graphitized petroleum coke skeleton material is 1-10 mm, and the particle size of the graphitized petroleum coke powder is 0.1-0.15 mm.

[0011] Furthermore, by mass percentage, the composition of the mixture is: 40-50% graphitized petroleum coke skeleton material, 20-40% graphitized petroleum coke powder, and the balance being modified asphalt.

[0012] Furthermore, the working conditions for kneading and mixing are as follows: graphitized petroleum coke skeleton material and graphitized petroleum coke powder are added from the powder inlet of the kneader, and the oil bath is heated to 90-150℃; the modified asphalt is heated to 150-180℃ and added to the kneader through the asphalt feeding inlet, and stirred; the material is conveyed to the upper part of the kneader through a circulating material pump, and then enters the lower part of the kneader through a screening screen, so that the vacuum degree inside the kneader is -0.099~-0.07MPa, stirred for 1-10 hours, and then discharged to obtain the kneaded material.

[0013] Furthermore, the preparation of modified asphalt includes the following steps: heating the base asphalt to 130-140℃, adding organosilicon polyurethane prepolymer, shearing at 1100-1300r / min for 8-10min, adding cage-like polyol, continuing shearing for 25-35min, adding composite basalt fiber, continuing shearing for 5-10min, and then cooling to 75-82℃ and holding for 5-7h to obtain modified asphalt.

[0014] Furthermore, by weight, the raw material composition of the modified asphalt is as follows: 20-22 parts of base asphalt, 12-15 parts of organosilicon polyurethane prepolymer, 1-2 parts of cage-like polyol, and 0.1-0.3 parts of composite basalt fiber.

[0015] Furthermore, the preparation of cage-like polyols includes the following steps: mixing polycaprolactone triol, polycaprolactone tetraol, and ethyl acetate, dehydrating for 1-2 hours, adding dicyclohexylmethane diisocyanate, keeping warm at 78-82℃ for 4-5 hours, cooling to 30-40℃, adding butyl acetate, and rotary evaporating to obtain cage-like polyols.

[0016] Furthermore, the preparation of the organosilicon polyurethane prepolymer includes the following steps: Under a nitrogen atmosphere, hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate, and N,N-dimethylacetamide are mixed, isophorone diisocyanate is added, the temperature is raised to 72-78℃ and held for 2-3 hours, then cooled to 35-40℃, a mixture of adipate dihydrazide and N,N-dimethylacetamide is added, the temperature is maintained for another 3-4 hours, 4,4'-diaminodiphenyl disulfide is added, the temperature is raised to 50-60℃ and held for 1-2 hours, and the material is discharged to obtain the organosilicon polyurethane prepolymer.

[0017] Furthermore, the preparation of composite basalt fibers includes the following steps:

[0018] (1) Basalt fibers are ultrasonically cleaned with isopropanol, hydrochloric acid, distilled water and anhydrous ethanol in sequence, and dried to obtain acidified basalt fibers; a nano-zirconium sol solution with a mass fraction of 1-2% is prepared, and the acidified basalt fibers are impregnated, vacuum filtered 12-15 times, washed and dried to obtain pretreated basalt fibers.

[0019] (2) Mix zirconium chloride, isopropyl titanate, N,N-dimethylformamide and hydrochloric acid to form solution A; mix terephthalic acid and N,N-dimethylformamide to form solution B; immerse the pretreated basalt fiber in the mixture of zirconium chloride, isopropyl titanate and N,N-dimethylformamide for 10-15 min, remove the basalt fiber and dry it, then put it into solution A in sequence, keep it at 130-140℃ for 10-15 min, wash it with N,N-dimethylformamide 3 times, then put it into solution B and keep it at 130-140℃ for 10-15 min, wash it with N,N-dimethylformamide 3 times, and repeat the operation of putting it into solution A and solution B 12-15 times to obtain modified basalt fiber;

[0020] (3) Mix modified basalt fiber, cage-like polyol and deionized water, keep warm at 58-62℃ for 22-24h, centrifuge, wash and dry to obtain composite basalt fiber.

[0021] The beneficial effects of this invention are:

[0022] This invention provides a high-resistance crucible for graphitization of lithium battery anode materials and its preparation process. Through process and composition design, a high-resistance crucible with good uniformity of thermal expansion coefficient and crack resistance is obtained, thereby effectively improving the service life of the crucible.

[0023] During the mixing process, the materials are continuously separated through a sieve under vacuum to prevent the graphitized petroleum coke skeleton material from agglomerating. This ensures the uniformity of the dispersion of the graphitized petroleum coke skeleton material, graphitized petroleum coke powder, and modified asphalt, thereby improving the uniformity of the coefficient of thermal expansion, increasing the yield of the crucible after calcination, and enhancing the service life and performance of the crucible.

[0024] To effectively improve the crack resistance and thermal expansion coefficient of crucibles, asphalt is modified. Current market methods for modifying asphalt often involve directly blending modifiers with the asphalt to improve its performance, resulting in uneven mixing and decreased uniformity. In this invention, hydroxyl-terminated polydimethylsiloxane and isophorone diisocyanate are used as raw materials to synthesize an isocyanate-terminated prepolymer under the catalysis of dibutyltin dilaurate. Then, an organosilicon polyurethane prepolymer is synthesized using adipate dihydrazide and 4,4'-diaminodiphenyl disulfide as chain extenders. This prepolymer is then further polymerized in situ with composite basalt fibers and cage-like polyols to perform composite modification of the asphalt. This fully leverages the advantages of nanomaterials and fiber materials, creating a synergistic effect to prepare modified asphalt, thereby effectively improving the high-temperature rheological properties and high-temperature resistance of asphalt.

[0025] In the preparation of organosilicon polyurethane prepolymers, hydroxyl-terminated polydimethylsiloxanes are introduced to effectively improve the thermal stability of the crucible. Adipate dihydrazide and 4,4'-diaminodiphenyl disulfide are used as chain extenders to impart hydrogen bonds and disulfide bonds to the organosilicon polyurethane prepolymers, giving them excellent self-healing properties, thereby improving the adhesion of modified asphalt and significantly increasing the yield of the calcined crucible. In this invention, polycaprolactone triol, polycaprolactone tetraol, and dicyclohexylmethane diisocyanate are used to prepare a cage-like polyol with multiple hydroxyl groups. This polyol is introduced into the modified asphalt to further impart multiple active sites to the modified asphalt, enhance the bonding strength between the modified asphalt and the graphitized petroleum coke skeleton material and graphitized petroleum coke powder, and improve the various properties of the crucible.

[0026] To further improve the high-temperature resistance of modified asphalt, basalt fibers were introduced in situ into the modified asphalt. Because basalt fibers are reactive, in order to improve the uniformity of basalt fiber dispersion in asphalt, the basalt fibers were modified by ultrasonic cleaning with isopropanol, hydrochloric acid, distilled water, and anhydrous ethanol in sequence to obtain activated basalt fibers. Then, a zirconium-titanium bimetallic organic framework with terephthalic acid as the organic ligand was grown layer by layer on the surface of the activated basalt fibers using a layer-by-layer self-assembly method. The framework was then modified with cage-like polyols to obtain composite basalt fibers, which maintained the homogeneity of the crucible and thus improved the crucible's crack resistance. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that if the embodiments of the present invention involve directional indicators such as up, down, left, right, front, and back, these directional indicators are only used to explain the relative positional relationship and movement of components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0029] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1: A process for preparing a high-resistance crucible for graphitization of lithium battery anode materials, comprising the following steps:

[0031] S1: Graphitized petroleum coke is crushed, ground, and sieved to obtain graphitized petroleum coke skeleton material and graphitized petroleum coke powder.

[0032] The particle size of the graphitized petroleum coke skeleton material is 3 mm, and the particle size of the graphitized petroleum coke powder is 0.12 mm.

[0033] S2: Mix graphitized petroleum coke skeleton material, graphitized petroleum coke powder, and modified asphalt to obtain a mixture.

[0034] The composition of the mixture by mass percentage is: 45% graphitized petroleum coke skeleton material, 30% graphitized petroleum coke powder, and the balance being medium-temperature modified asphalt.

[0035] The working conditions for kneading and mixing are as follows: graphitized petroleum coke skeleton material and graphitized petroleum coke powder are added from the powder inlet of the kneader, and the oil bath is heated to 110℃; the medium-temperature modified asphalt is heated to 160℃ and added to the kneader through the asphalt feeding inlet, and stirred; the material is conveyed to the upper part of the kneader through the circulating material pump, and then enters the lower part of the kneader through the screening screen, so that the vacuum degree inside the kneader is -0.08MPa, and stirred for 2 hours, and then discharged to obtain the kneaded material;

[0036] S3: The mixed materials are sequentially molded, calcined, and processed to obtain a high-resistant crucible for graphitization of lithium battery anode materials.

[0037] Example 2: A process for preparing a high-resistance crucible for graphitization of lithium battery anode materials, comprising the following steps:

[0038] S1: Graphitized petroleum coke is crushed, ground, and sieved to obtain graphitized petroleum coke skeleton material and graphitized petroleum coke powder.

[0039] The graphitized petroleum coke skeleton material has a particle size of 1 mm, and the graphitized petroleum coke powder has a particle size of 0.1 mm.

[0040] S2: Mix graphitized petroleum coke skeleton material, graphitized petroleum coke powder, and modified asphalt to obtain a mixture.

[0041] The composition of the mixture by mass percentage is: 40% graphitized petroleum coke skeleton material, 20% graphitized petroleum coke powder, and the balance being modified asphalt.

[0042] The working conditions for kneading and mixing are as follows: graphitized petroleum coke skeleton material and graphitized petroleum coke powder are added from the powder inlet of the kneader, and the oil bath is heated to 90°C; modified asphalt is heated to 150°C and added to the kneader through the asphalt feeding inlet, and then stirred; the material is conveyed to the upper part of the kneader through a circulating material pump, and then enters the lower part of the kneader through a sieve, so that the vacuum degree inside the kneader is -0.07MPa, and stirred for 1 hour, and then discharged to obtain the kneaded material;

[0043] The preparation of the modified asphalt includes the following steps: heating the base asphalt to 130°C, adding organosilicon polyurethane prepolymer, shearing at 1100 r / min for 10 min, adding cage-like polyol, continuing shearing for 25 min, adding composite basalt fiber, continuing shearing for 5 min, and then cooling to 75°C and holding for 7 h to obtain the modified asphalt.

[0044] The raw material composition of the modified asphalt by weight is as follows: 20 parts of base asphalt, 12 parts of organosilicon polyurethane prepolymer, 1 part of cage-like polyol, and 0.1 parts of composite basalt fiber.

[0045] The preparation of cage-like polyols includes the following steps: 2.1g of polycaprolactone triol, 1.5g of polycaprolactone tetraol and 5g of ethyl acetate are mixed and dehydrated for 1 hour. 1.4g of dicyclohexylmethane diisocyanate is added and kept at 78℃ for 5 hours. The mixture is then cooled to 30℃ and 40g of butyl acetate is added. The mixture is then rotary evaporated to obtain cage-like polyols.

[0046] The preparation of the organosilicon polyurethane prepolymer includes the following steps: Under a nitrogen atmosphere, 6g of hydroxyl-terminated polydimethylsiloxane, 2 drops of dibutyltin dilaurate, and 2.5mL of N,N-dimethylacetamide are mixed, 1.1g of isophorone diisocyanate is added, the temperature is raised to 72℃ and kept at that temperature for 3h, then cooled to 35℃, a mixture of 0.3g of adipic acid dihydrazide and 15mL of N,N-dimethylacetamide is added, the temperature is kept at that temperature for another 3h, 0.2g of 4,4'-diaminodiphenyl disulfide is added, the temperature is raised to 50℃ and kept at that temperature for 2h, and the material is discharged to obtain the organosilicon polyurethane prepolymer;

[0047] The preparation of composite basalt fibers includes the following steps:

[0048] (1) The basalt fiber was ultrasonically cleaned with isopropanol, 2mol / L hydrochloric acid, distilled water and anhydrous ethanol in sequence, and dried to obtain acidified basalt fiber; a nano-zirconium sol solution with a mass fraction of 1% was prepared, and the acidified basalt fiber was impregnated, vacuum filtered 12 times, washed and dried to obtain pretreated basalt fiber.

[0049] (2) Mix 2.5g zirconium chloride, 2mmol isopropyl titanate, 140mL N,N-dimethylformamide, and 4.2mL hydrochloric acid with a mass concentration of 12% to form solution A; mix 1.7g terephthalic acid and 140mL N,N-dimethylformamide to form solution B; immerse 2g of pretreated basalt fiber in a mixture of 0.2g zirconium chloride, 1mmol isopropyl titanate, and 10mL N,N-dimethylformamide for 10min, remove the basalt fiber and dry it, then put it into solution A and keep it at 130℃ for 15min, wash it with N,N-dimethylformamide 3 times, then put it into solution B and keep it at 130℃ for 15min, wash it with N,N-dimethylformamide 3 times, and repeat the operation of putting it into solution A and solution B 12 times to obtain modified basalt fiber;

[0050] (3) Mix 3g of modified basalt fiber, 2g of cage-like polyol and 200mL of deionized water, keep warm at 58℃ for 24h, centrifuge, wash and dry to obtain composite basalt fiber.

[0051] S3: The mixed materials are sequentially molded, calcined, and processed to obtain a high-resistant crucible for graphitization of lithium battery anode materials.

[0052] Example 3: A process for preparing a high-resistance crucible for graphitization of lithium battery anode materials, comprising the following steps:

[0053] S1: Graphitized petroleum coke is crushed, ground, and sieved to obtain graphitized petroleum coke skeleton material and graphitized petroleum coke powder.

[0054] The graphitized petroleum coke skeleton material has a particle size of 3 mm, and the graphitized petroleum coke powder has a particle size of 0.12 mm.

[0055] S2: Mix graphitized petroleum coke skeleton material, graphitized petroleum coke powder, and modified asphalt to obtain a mixture.

[0056] The composition of the mixture by mass percentage is: 45% graphitized petroleum coke skeleton material, 30% graphitized petroleum coke powder, and the balance being modified asphalt.

[0057] The working conditions for kneading and mixing are as follows: graphitized petroleum coke skeleton material and graphitized petroleum coke powder are added from the powder inlet of the kneader, and the oil bath is heated to 110℃; the modified asphalt is heated to 160℃ and added to the kneader through the asphalt feeding inlet, and then stirred; the material is conveyed to the upper part of the kneader through a circulating material pump, and then enters the lower part of the kneader through a sieve, so that the vacuum degree inside the kneader is -0.08MPa, and stirred for 2 hours, and then discharged to obtain the kneaded material;

[0058] The preparation of the modified asphalt includes the following steps: heating the base asphalt to 135°C, adding organosilicon polyurethane prepolymer, shearing at 1200 r / min for 9 min, adding cage-like polyol, continuing shearing for 30 min, adding composite basalt fiber, continuing shearing for 8 min, and then cooling to 80°C and holding for 6 h to obtain the modified asphalt.

[0059] The raw material composition of the modified asphalt by weight is as follows: 21 parts base asphalt, 13 parts organosilicon polyurethane prepolymer, 1.5 parts cage-like polyol, and 0.2 parts composite basalt fiber.

[0060] The preparation of cage-like polyols includes the following steps: 2.1g of polycaprolactone triol, 1.5g of polycaprolactone tetraol and 5g of ethyl acetate are mixed and dehydrated for 1.5h. 1.4g of dicyclohexylmethane diisocyanate is added and kept at 80℃ for 4.5h. The mixture is then cooled to 35℃ and 40g of butyl acetate is added. The mixture is then rotary evaporated to obtain cage-like polyols.

[0061] The preparation of the organosilicon polyurethane prepolymer includes the following steps: Under a nitrogen atmosphere, 6g of hydroxyl-terminated polydimethylsiloxane, 2 drops of dibutyltin dilaurate, and 2.5mL of N,N-dimethylacetamide are mixed, 1.1g of isophorone diisocyanate is added, the temperature is raised to 75℃ and kept at that temperature for 2.5h, then cooled to 38℃, a mixture of 0.3g of adipate dihydrazide and 15mL of N,N-dimethylacetamide is added, the temperature is kept at that temperature for another 3.5h, 0.2g of 4,4'-diaminodiphenyl disulfide is added, the temperature is raised to 55℃ and kept at that temperature for 1-2h, and the material is discharged to obtain the organosilicon polyurethane prepolymer;

[0062] The preparation of composite basalt fibers includes the following steps:

[0063] (1) Basalt fibers were ultrasonically cleaned in sequence with isopropanol, 2mol / L hydrochloric acid, distilled water and anhydrous ethanol, and dried to obtain acidified basalt fibers; a nano-zirconium sol solution with a mass fraction of 1.5% was prepared, and the acidified basalt fibers were impregnated, vacuum filtered 13 times, washed and dried to obtain pretreated basalt fibers.

[0064] (2) Mix 2.5g zirconium chloride, 2mmol isopropyl titanate, 140mL N,N-dimethylformamide, and 4.2mL hydrochloric acid with a mass concentration of 12% to form solution A; mix 1.7g terephthalic acid and 140mL N,N-dimethylformamide to form solution B; immerse 2g of pretreated basalt fiber in a mixture of 0.2g zirconium chloride, 1mmol isopropyl titanate, and 10mL N,N-dimethylformamide for 13min, remove the basalt fiber and dry it, then put it into solution A and keep it at 135℃ for 13min, wash it with N,N-dimethylformamide 3 times, then put it into solution B and keep it at 135℃ for 13min, wash it with N,N-dimethylformamide 3 times, and repeat the operation of putting it into solution A and solution B 13 times to obtain modified basalt fiber;

[0065] (3) Mix 3g of modified basalt fiber, 2g of cage-like polyol and 200mL of deionized water, keep warm at 60℃ for 23h, centrifuge, wash and dry to obtain composite basalt fiber.

[0066] S3: The mixed materials are sequentially molded, calcined, and processed to obtain a high-resistant crucible for graphitization of lithium battery anode materials.

[0067] Example 4: A process for preparing a high-resistance crucible for graphitization of lithium battery anode materials, comprising the following steps:

[0068] S1: Graphitized petroleum coke is crushed, ground, and sieved to obtain graphitized petroleum coke skeleton material and graphitized petroleum coke powder.

[0069] The graphitized petroleum coke skeleton material has a particle size of 10 mm, and the graphitized petroleum coke powder has a particle size of 0.15 mm.

[0070] S2: Mix graphitized petroleum coke skeleton material, graphitized petroleum coke powder, and modified asphalt to obtain a mixture.

[0071] The composition of the mixture by mass percentage is: 50% graphitized petroleum coke skeleton material, 40% graphitized petroleum coke powder, and the balance being modified asphalt.

[0072] The working conditions for kneading and mixing are as follows: graphitized petroleum coke skeleton material and graphitized petroleum coke powder are added from the powder inlet of the kneader, and the oil bath is heated to 150°C; modified asphalt is heated to 180°C and added to the kneader through the asphalt feeding inlet, and then stirred; the material is conveyed to the upper part of the kneader through a circulating material pump, and then enters the lower part of the kneader through a sieve, so that the vacuum degree inside the kneader is -0.099MPa, and stirred for 10 hours, and then discharged to obtain the kneaded material;

[0073] The preparation of the modified asphalt includes the following steps: heating the base asphalt to 140°C, adding organosilicon polyurethane prepolymer, shearing at 1300 r / min for 8 min, adding cage-like polyol, continuing shearing for 35 min, adding composite basalt fiber, continuing shearing for 10 min, and then cooling to 82°C and holding for 5 h to obtain the modified asphalt.

[0074] The raw material composition of the modified asphalt by weight is as follows: 22 parts of base asphalt, 15 parts of organosilicon polyurethane prepolymer, 2 parts of cage-like polyol, and 0.3 parts of composite basalt fiber.

[0075] The preparation of cage-like polyols includes the following steps: 2.1g of polycaprolactone triol, 1.5g of polycaprolactone tetraol and 5g of ethyl acetate are mixed and dehydrated for 2 hours. 1.4g of dicyclohexylmethane diisocyanate is added and kept at 82℃ for 4 hours. The mixture is then cooled to 40℃ and 40g of butyl acetate is added. The mixture is then rotary evaporated to obtain cage-like polyols.

[0076] The preparation of the organosilicon polyurethane prepolymer includes the following steps: Under a nitrogen atmosphere, 6g of hydroxyl-terminated polydimethylsiloxane, 2 drops of dibutyltin dilaurate, and 2.5mL of N,N-dimethylacetamide are mixed, 1.1g of isophorone diisocyanate is added, the temperature is raised to 78℃ and kept at that temperature for 2h, then cooled to 40℃, a mixture of 0.3g of adipic acid dihydrazide and 15mL of N,N-dimethylacetamide is added, the temperature is maintained for another 4h, 0.2g of 4,4'-diaminodiphenyl disulfide is added, the temperature is raised to 60℃ and kept at that temperature for 1h, and the material is discharged to obtain the organosilicon polyurethane prepolymer;

[0077] The preparation of composite basalt fibers includes the following steps:

[0078] (1) Basalt fibers were ultrasonically cleaned with isopropanol, 2 mol / L hydrochloric acid, distilled water and anhydrous ethanol in sequence, and dried to obtain acidified basalt fibers; a nano-zirconium sol solution with a mass fraction of 2% was prepared, and the acidified basalt fibers were impregnated, vacuum filtered 15 times, washed and dried to obtain pretreated basalt fibers.

[0079] (2) Mix 2.5g zirconium chloride, 2mmol isopropyl titanate, 140mL N,N-dimethylformamide, and 4.2mL hydrochloric acid with a mass concentration of 12% to form solution A; mix 1.7g terephthalic acid and 140mL N,N-dimethylformamide to form solution B; immerse 2g of pretreated basalt fiber in a mixture of 0.2g zirconium chloride, 1mmol isopropyl titanate, and 10mL N,N-dimethylformamide for 15min, remove the basalt fiber and dry it, then put it into solution A and keep it at 140℃ for 10min, wash it with N,N-dimethylformamide 3 times, then put it into solution B and keep it at 140℃ for 10min, wash it with N,N-dimethylformamide 3 times, and repeat the operation of putting it into solution A and solution B 15 times to obtain modified basalt fiber;

[0080] (3) Mix 1g of modified basalt fiber, 4g of cage-like polyol and 200mL of deionized water, keep warm at 62℃ for 22h, centrifuge, wash and dry to obtain composite basalt fiber.

[0081] S3: The mixed materials are sequentially molded, calcined, and processed to obtain a high-resistant crucible for graphitization of lithium battery anode materials.

[0082] Comparative Example 1: By mass percentage, the composition of the kneaded material is: 45% graphitized petroleum coke skeleton material, 30% graphitized petroleum coke powder, and the balance being medium-temperature modified asphalt; the particle size of the graphitized petroleum coke skeleton material is 3 mm, and the particle size of the graphitized petroleum coke powder is 0.12 mm; the material is kneaded and mixed using a double-layer kneader. First, the graphitized petroleum coke skeleton material and graphitized petroleum coke powder are dry-mixed in the upper layer for 0.5 h, then transferred to the lower layer at a temperature of 110 °C. Medium-temperature modified asphalt at 120 °C is added and stirred for 1 h. The mixture is then transferred to a mixer and stirred at 110 °C for 0.5 h. After molding, calcining, and processing, a graphite crucible is obtained.

[0083] Comparative Example 2: Example 3 served as the control group. No adipic dihydrazide or 4,4'-diaminodiphenyl disulfide was added, and other processes were normal.

[0084] Comparative Example 3: Using Example 3 as the control group, no cage-like polyols were prepared, and other processes were normal.

[0085] Comparative Example 4: Using Example 3 as the control group, basalt fiber was used to replace composite basalt fiber, while other processes were normal.

[0086] Source of raw materials (for illustrative purposes only):

[0087] Graphitized petroleum coke 001: Hunan Xintan New Materials Co., Ltd.; Medium-temperature modified asphalt 8052-42-4: Jining Lumei Chemical Co., Ltd.; Matrix asphalt AH-70: Shandong Expressway Group; Polycaprolactone tetraol CAPA4041: Shanghai Shanji Chemical Co., Ltd.; Dicyclohexylmethane diisocyanate 5124-30-1: Wuhan Jixin Yibang Biotechnology Co., Ltd.; N,N-Dimethylacetamide 127-19-5: Pande (Shanghai) International Trade Co., Ltd.; Basalt fiber (diameter 13μm): Shanxi Jintou Basalt Development Co., Ltd.; Nano-zirconium sol 1314-23-4: Xuancheng Jingrui New Materials Co., Ltd. Limited Liability Company; Terephthalic acid 185361: Sigma-Aldrich (Shanghai) Trading Co., Ltd.; Polycaprolactone triol P303596, Hydroxyl-terminated polydimethylsiloxane P304442, Dibutyltin dilaurate D100274, Iophorone diisocyanate I109582, Adipic acid dihydrazide A109760, 4,4'-Diaminodiphenyl disulfide A101817, N,N-Dimethylformamide D111999, Zirconium chloride Z109460, Isopropyl titanate T105736: Aladdin Reagent; Ethyl acetate, Butyl acetate, Isopropanol, Hydrochloric acid, Ethanol, Analytical grade: Sinopharm Group Reagent.

[0088] Performance testing: Performance tests were conducted on the crucibles prepared in the examples and comparative examples.

[0089] The dimensions of the crucible in the examples and comparative examples are: bottom diameter 600 mm, height 1200 mm, and wall thickness 5 mm;

[0090] Relative range of thermal expansion coefficient: The thermal expansion coefficient was determined according to GB / T7320-2018. Cylindrical specimens of Φ5mm*15mm were taken vertically from top to bottom at 60mm intervals on the surface of a crucible sample with dimensions of Φ600*1200mm and a wall thickness of 5mm. Eight groups were taken from each crucible, and the relative range of the thermal expansion coefficient was calculated. Crack resistance: 25g of potassium carbonate was placed in the crucible and kept at 1200℃ for 4 hours. After natural cooling, the presence of cracks was tested; no cracks were considered acceptable. Average service life: The prepared crucibles were used for the graphitization of carbon materials at a working temperature of 2800℃. The service life of the crucibles was observed, with 20 crucibles taken from each group as samples. The results are shown in Table 1 below.

[0091] Table 1

[0092] Range of thermal expansion coefficients (%) Crack resistance Average service life (times) Example 1 5.37 qualified 13 Example 2 3.61 qualified 16 Example 3 3.51 qualified 16 Example 4 3.55 qualified 16 Comparative Example 1 21.26 / 5 Comparative Example 2 4.15 / / Comparative Example 3 4.43 / / Comparative Example 4 4.68 / /

[0093] This invention provides a high-resistance crucible for graphitization of lithium battery anode materials and its preparation process. Through process and composition design, a high-resistance crucible with good uniformity of thermal expansion coefficient and crack resistance is obtained, thereby effectively improving the service life of the crucible. In the table, / indicates that the item was not tested.

[0094] Comparing Example 1 with Comparative Example 1, during the kneading and stirring process, the materials were continuously separated through a sieve under vacuum to prevent the graphitized petroleum coke skeleton material from agglomerating. This ensured the uniformity of the dispersion of the graphitized petroleum coke skeleton material, graphitized petroleum coke powder, and modified asphalt, thereby improving the uniformity of the coefficient of thermal expansion, increasing the yield of the crucible after calcination, and improving the service life and performance of the crucible.

[0095] Comparing Example 3 with Comparative Example 2, in the preparation of the organosilicon polyurethane prepolymer, hydroxyl-terminated polydimethylsiloxane was introduced to effectively improve the thermal stability of the crucible. Adipate dihydrazide and 4,4'-diaminodiphenyl disulfide were used as chain extenders to impart hydrogen bonds and disulfide bonds to the organosilicon polyurethane prepolymer, giving it excellent self-healing properties, thereby improving the adhesion of the modified asphalt and significantly improving the crucible's crack resistance.

[0096] Comparing Example 3 with Comparative Example 3, in this invention, polycaprolactone triol, polycaprolactone tetraol, and dicyclohexylmethane diisocyanate are used to prepare a cage-like polyol with multiple hydroxyl groups. This polyol is then introduced into modified asphalt to further impart multiple active sites to the modified asphalt, enhance the bonding strength between the modified asphalt and the graphitized petroleum coke skeleton material and graphitized petroleum coke powder, and improve the various properties of the crucible.

[0097] Comparing Example 3 with Comparative Example 4, in order to further improve the high-temperature resistance of modified asphalt, basalt fibers were introduced in situ into the modified asphalt. Because basalt fibers are reactive and in order to improve the uniformity of basalt fiber dispersion in asphalt, the basalt fibers were modified by ultrasonic cleaning with isopropanol, hydrochloric acid, distilled water and anhydrous ethanol in sequence to obtain activated basalt fibers. Then, a zirconium-titanium bimetallic organic framework with terephthalic acid as the organic ligand was grown layer by layer on the surface of the activated basalt fibers using a layer-by-layer self-assembly method, and modified with cage-like polyols to obtain composite basalt fibers, so as to maintain the uniformity of the crucible and thus improve the crack resistance of the crucible.

[0098] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention's specification under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A preparation process for a high-resistance crucible for graphitization of lithium battery anode materials, characterized in that, Includes the following steps: S1: Graphitized petroleum coke is crushed, ground, and sieved to obtain graphitized petroleum coke skeleton material and graphitized petroleum coke powder. Under a nitrogen atmosphere, hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate, and N,N-dimethylacetamide are mixed, isophorone diisocyanate is added, the temperature is raised to 72-78℃ and held for 2-3 hours, then cooled to 35-40℃, a mixture of adipic dihydrazide and N,N-dimethylacetamide is added, the temperature is maintained for another 3-4 hours, 4,4'-diaminodiphenyl disulfide is added, the temperature is raised to 50-60℃ and held for 1-2 hours, and the material is discharged to obtain an organosilicon polyurethane prepolymer. Basalt fibers were sequentially ultrasonically cleaned with isopropanol, hydrochloric acid, distilled water, and anhydrous ethanol, and then dried to obtain acidified basalt fibers. A 1-2% (w / w) nano-zirconium sol solution was prepared, and the acidified basalt fibers were impregnated with it. The fibers were then vacuum filtered 12-15 times, washed, and dried to obtain pretreated basalt fibers. Zirconium chloride, isopropyl titanate, N,N-dimethylformamide, and hydrochloric acid were mixed to form solution A. Terephthalic acid and N,N-dimethylformamide were mixed to form solution B. The pretreated basalt fibers were then immersed in the mixture of zirconium chloride, isopropyl titanate, and N,N-dimethylformamide. After staining for 10-15 minutes, the basalt fibers are removed, dried, and then sequentially placed in solution A and kept at 130-140℃ for 10-15 minutes. They are then washed three times with N,N-dimethylformamide. Next, they are placed in solution B and kept at 130-140℃ for 10-15 minutes, washed three times with N,N-dimethylformamide. This process of placing the fibers in solutions A and B is repeated 12-15 times to obtain modified basalt fibers. The modified basalt fibers, cage-like polyol, and deionized water are mixed and kept at 58-62℃ for 22-24 hours. After centrifugation, washing, and drying, composite basalt fibers are obtained. The base asphalt is heated to 130-140℃, and organosilicon polyurethane prepolymer is added. It is sheared at 1100-1300r / min for 8-10min, cage-like polyol is added, and shearing continues for 25-35min. Composite basalt fiber is added, and shearing continues for 5-10min. Then, the temperature is lowered to 75-82℃ and kept at that temperature for 5-7h to obtain modified asphalt. S2: Add graphitized petroleum coke skeleton material and graphitized petroleum coke powder through the powder inlet of the kneader, and heat the oil bath to 90-150℃; heat the modified asphalt to 150-180℃ and add it to the kneader through the asphalt feeding inlet, and stir; convey the material to the upper part of the kneader through the circulating material pump, and then enter the lower part of the kneader through the screening screen, so that the vacuum degree inside the kneader is -0.099~-0.07MPa, stir for 1-10 hours, and then discharge to obtain the kneaded material; S3: The mixed materials are sequentially molded, calcined, and processed to obtain a high-resistant crucible for graphitization of lithium battery anode materials.

2. The preparation process of a high-resistant crucible for graphitization of lithium battery anode materials according to claim 1, characterized in that, The graphitized petroleum coke skeleton material has a particle size of 1-10 mm, and the graphitized petroleum coke powder has a particle size of 0.1-0.15 mm.

3. The preparation process of a high-resistant crucible for graphitization of lithium battery anode materials according to claim 1, characterized in that, The composition of the mixture by mass percentage is: 40-50% graphitized petroleum coke skeleton material, 20-40% graphitized petroleum coke powder, and the balance being modified asphalt.

4. The preparation process of a high-resistant crucible for graphitization of lithium battery anode materials according to claim 1, characterized in that, The raw material composition of modified asphalt by weight is as follows: 20-22 parts of base asphalt, 12-15 parts of organosilicon polyurethane prepolymer, 1-2 parts of cage-like polyol, and 0.1-0.3 parts of composite basalt fiber.

5. The preparation process of a high-resistant crucible for graphitization of lithium battery anode materials according to claim 1, characterized in that, The preparation of the cage-like polyol includes the following steps: mixing polycaprolactone triol, polycaprolactone tetraol, and ethyl acetate, dehydrating for 1-2 hours, adding dicyclohexylmethane diisocyanate, keeping warm at 78-82℃ for 4-5 hours, cooling to 30-40℃, adding butyl acetate, and rotary evaporating to obtain the cage-like polyol.

6. A high-resistance crucible for graphitization of lithium battery anode materials, characterized in that, It is prepared by the preparation process described in any one of claims 1-5.