Sagger for containing positive electrode material and preparation method of sagger

Abstract

The invention relates to the technical field of saggers, in particular to a sagger for containing a positive electrode material and a preparation method of the sagger. The sagger is prepared from the following raw materials in parts by weight: 20-30 parts of cordierite, 10-15 parts of mullite, 6-10 parts of spodumene, 5-10 parts of boron nitride, 3-6 parts of silicon carbide, 5-10 parts of zirconium oxide and 1.5-2.5 parts of a binding agent. The protective coating is prepared from the following raw materials in parts by weight: 45-55 parts of corundum, 15-20 parts of spinel, 6-10 parts of clay, 3-5 parts of chromium carbide and 6-10 parts of titanium nitride; the sagger prepared by the invention not only has excellent high temperature resistance and corrosion resistance, but also has outstanding thermal shock stability and wear resistance, the service life of the sagger is effectively guaranteed, the sintering quality of the positive electrode material is also improved, and the quality of the positive electrode material is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of saggers, in particular to a sagger for holding positive electrode materials and a preparation method thereof. Background Art

[0002] In the production process of positive electrode materials for lithium batteries, high-temperature sintering is a key process. The performance of the sagger, as a container for carrying positive electrode materials for sintering, directly affects the quality and production efficiency of the positive electrode materials. Traditional saggers are prone to deformation, corrosion, and peeling when faced with high temperatures and complex chemical environments, resulting in short sagger life and frequent replacement, which increases production costs. Furthermore, traditional saggers have deficiencies in heat transfer uniformity and compatibility with positive electrode materials, which can lead to unstable sintering quality of positive electrode materials and affect battery performance consistency. Therefore, it is urgent to develop a sagger that is high-performance, long-life, and adaptable to the production needs of positive electrode materials.

[0003] Based on this, the present invention provides a sagger for containing positive electrode materials and a preparation method thereof to solve the above-mentioned technical problems. Summary of the Invention

[0004] The object of the present invention is to provide a sagger for holding positive electrode materials and a preparation method thereof. The prepared sagger not only has excellent high temperature resistance and corrosion resistance, but also has outstanding thermal shock stability and wear resistance, which effectively ensures the service life of the sagger while improving the sintering quality of the positive electrode material and ensuring its quality.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a sagger for holding a positive electrode material, comprising the following steps:

[0007] Step 1: Weigh 20 to 30 parts of cordierite, 10 to 15 parts of mullite, 6 to 10 parts of spodumene, 5 to 10 parts of boron nitride, 3 to 6 parts of silicon carbide, 5 to 10 parts of zirconium oxide, and 1.5 to 2.5 parts of a binder by weight; and dry all the raw materials except the binder and store them for future use;

[0008] Step 2: Weigh 45-55 parts of corundum, 15-20 parts of spinel, 6-10 parts of clay, 3-5 parts of chromium carbide, and 6-10 parts of titanium nitride, respectively, by weight; put all the raw materials into a grinding device; after grinding, add 3-6 parts of cerium dioxide powder to the resulting mixed powder, mix well, transfer to a ball mill, add anhydrous ethanol, and after ball milling, store the resulting protective coating for future use;

[0009] Step 3, putting the dried raw materials in step 1 into a high-speed mixer, adding zinc stearate with a mass of 0.5-1.0% of the total mass of the raw materials, and mixing at a speed of 1000-1200 r / min for 30-50 minutes; adding a binder and continuing to stir for 15-25 minutes, then adding a water-based binder to the obtained mixed solid material at a dosage ratio of 0.06-0.1 mL / g, mixing and aging for 15-24 hours to form a blank; injecting the blank into an isostatic pressing device with a microchannel mold for stamping;

[0010] Step 4: Dry the formed green body at a temperature of 40-50°C for 12-15 hours, and then at a temperature of 80-90°C for 8-10 hours; after drying, transfer it to a degreasing furnace for degreasing;

[0011] Step 5: Transfer the degreased green body into a high-temperature sintering furnace, and raise the furnace temperature to 1400-1600°C at a rate of 4-6°C / min. After heat preservation for 4-6 hours, cool it in the furnace to obtain a sagger base;

[0012] Step 6: Immerse the sagger base in the protective slurry for 10 to 15 minutes, take it out and dry it, then transfer it to a high-temperature furnace for high-temperature curing. After curing is completed, the sagger containing the positive electrode material is obtained.

[0013] Furthermore, in the step 1, the particle size of boron nitride, silicon carbide and zirconium oxide is 0.01 to 0.03 mm; the particle size of cordierite, mullite and spodumene is 0.04 to 0.08 mm; and the drying temperature of cordierite, mullite, spodumene, boron nitride and silicon carbide is 100 to 120° C., and the drying time is 6 to 8 hours; when drying zirconium oxide, a vacuum drying process is adopted, the drying temperature is set to 80 to 90° C., the drying time is 3 to 5 hours, and the vacuum degree is 0.01 MPa.

[0014] Furthermore, the specific process of degreasing in step 4 is: transferring the dried green body into a degreasing furnace, raising the furnace temperature to 500-600°C at a rate of 1-2°C / min, and keeping it at this temperature for 2-3 hours for degreasing.

[0015] Furthermore, in step 2, the rotation speed during ball milling is set to 300-400 r / min, and the ball milling time is 8-10 h.

[0016] Furthermore, the binder is prepared by mixing silicon dioxide, boron oxide and potassium oxide in a weight ratio of 2 to 3:1 to 2:1.

[0017] Furthermore, the specific process of high temperature curing in step six is: raising the temperature of the high temperature furnace to 1300-1380° C. at a rate of 3-5° C. / min, and curing at this temperature for 3-5 hours.

[0018] Furthermore, in step three, the pressure during stamping is set to 150-200 MPa, and the holding time is set to 15-20 minutes.

[0019] Furthermore, the water-based adhesive in step three is a polyvinyl alcohol aqueous solution with a concentration of 5 to 8 wt%.

[0020] Furthermore, the chemical composition of the clay is: Al2O3 content ≥35.0wt%, SiO2 content ≥50.0wt%, K2O content ≤1.5wt%; and the particle size of the clay is ≤0.088mm.

[0021] In a second aspect, the present invention provides a sagger for containing positive electrode materials, which is prepared using the preparation method described above.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention uses cordierite, mullite, spodumene and the like as raw materials, and under high-temperature sintering conditions, a rich three-dimensional through-microchannel network is formed inside the sagger, which effectively improves the high-temperature resistance of the sagger while significantly improving its thermal shock stability. In addition, the microchannel network inside the sagger promotes the uniform circulation of gas within the sagger, improves the internal heat transfer path, and makes the temperature distribution inside the sagger more uniform, which helps to improve the consistency of the sintering quality of the positive electrode material and enhance the stability of battery performance.

[0024] 2. The protective coating is composed of corundum, spinel, clay, chromium carbide and titanium nitride. Under high-temperature sintering conditions, it can form a protective film layer on the surface of the sagger substrate. The presence of the protective film layer can effectively prevent the corrosive gases and substances generated during the sintering process of the positive electrode material at high temperature from eroding the sagger, thereby protecting the sagger to a certain extent. At the same time, the chemical properties of the raw materials in the sagger substrate are stable and have good compatibility with the positive electrode material, thus avoiding contamination of the positive electrode material and significantly improving the purity and quality consistency of the positive electrode material. Furthermore, titanium nitride can form a dense passivation film on the surface of the sagger substrate under high-temperature sintering conditions, which not only further reduces the chance of oxidation and corrosion of the sagger, but also effectively improves its wear resistance, effectively ensuring the quality of the sagger.

[0025] In summary, the sagger prepared by the present invention not only has excellent high temperature resistance and corrosion resistance, but also has outstanding thermal shock stability and wear resistance, which effectively ensures the service life of the sagger while improving the sintering quality of the positive electrode material and ensuring its quality. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for preparing a sagger for holding positive electrode materials comprises the following steps:

[0029] Step 1: Weigh 20 parts of cordierite, 10 parts of mullite, 6 parts of spodumene, 5 parts of boron nitride, 3 parts of silicon carbide, 5 parts of zirconium oxide, and 1.5 parts of a binder by weight; and dry all the raw materials except the binder and store them for future use;

[0030] The particle size of boron nitride, silicon carbide and zirconium oxide is 0.01 mm; the particle size of cordierite, mullite and spodumene is 0.04 mm; the drying temperature of cordierite, mullite, spodumene, boron nitride and silicon carbide is 100°C and the drying time is 8 hours; when drying zirconium oxide, a vacuum drying process is adopted, and the drying temperature is set to 80°C, the drying time is 5 hours, and the vacuum degree is 0.01 MPa;

[0031] Step 2: Weigh 45 parts of corundum, 15 parts of spinel, 6 parts of clay, 3 parts of chromium carbide, and 6 parts of titanium nitride, respectively, by weight; put all the raw materials into a grinding device; after grinding, add 3 parts of cerium dioxide powder to the resulting mixed powder, mix well, and transfer to a ball mill, control the ball-to-material ratio to 10:1, add anhydrous ethanol, and after ball milling, store the resulting protective coating for future use; set the ball milling speed to 300 r / min and the ball milling time to 10 hours;

[0032] The chemical composition of the clay is: Al2O3 content ≥35.0wt%, SiO2 content ≥50.0wt%, K2O content ≤1.5wt%; and the particle size of the clay is ≤0.088mm;

[0033] Step 3: Put the dried raw materials in step 1 into a high-speed mixer, add zinc stearate with a mass of 0.5% of the total mass of the raw materials, and mix at a speed of 1000 r / min for 30 minutes; add a binder and continue stirring for 15 minutes, then add a water-based binder to the obtained mixed solid material at a dosage ratio of 0.06 mL / g, mix well, and age for 15 hours to form a blank; inject the blank into an isostatic pressing device with a microchannel mold for stamping;

[0034] The binder is prepared by mixing silicon dioxide, boron oxide, and potassium oxide in a weight ratio of 2:1:1. The pressure during stamping is set to 150 MPa, and the holding time is set to 15 minutes. The water-based binder is a polyvinyl alcohol aqueous solution with a concentration of 5 wt%.

[0035] Step 4: Dry the formed green body at 40°C for 15 hours and then at 80°C for 10 hours. After drying, transfer it to a degreasing furnace and increase the furnace temperature to 500°C at a rate of 1°C / min. Keep it at this temperature for 3 hours for degreasing.

[0036] Step 5: Transfer the degreased green body into a high-temperature sintering furnace, raise the furnace temperature to 1400°C at a rate of 4°C / min, and heat-seal for 6 hours before cooling in the furnace to obtain a sagger base;

[0037] Step 6: Immerse the sagger base in the protective slurry for 10 minutes, take it out and dry it at 85°C for 5 hours; then transfer it to a high-temperature furnace and raise the furnace temperature to 1300°C at a rate of 3°C / min. After heat preservation and curing for 5 hours, the sagger containing the positive electrode material is obtained.

[0038] Example 2

[0039] A method for preparing a sagger for holding positive electrode materials comprises the following steps:

[0040] Step 1: Weigh 25 parts of cordierite, 12 parts of mullite, 8 parts of spodumene, 8 parts of boron nitride, 5 parts of silicon carbide, 7 parts of zirconium oxide, and 2 parts of a binder by weight; and dry all the raw materials except the binder and store them for future use;

[0041] The particle size of boron nitride, silicon carbide and zirconium oxide is 0.02 mm; the particle size of cordierite, mullite and spodumene is 0.06 mm; the drying temperature of cordierite, mullite, spodumene, boron nitride and silicon carbide is 110°C and the drying time is 7 hours; when drying zirconium oxide, a vacuum drying process is adopted, and the drying temperature is set to 85°C, the drying time is 4 hours, and the vacuum degree is 0.01 MPa;

[0042] Step 2: Weigh 50 parts of corundum, 18 parts of spinel, 8 parts of clay, 4 parts of chromium carbide, and 8 parts of titanium nitride, respectively, by weight; put all the raw materials into a grinding device; after grinding, add 5 parts of cerium dioxide powder to the obtained mixed powder, mix well, and transfer to a ball mill jar, control the ball-to-material ratio to 10:1, add anhydrous ethanol, and after ball milling, store the obtained protective coating for future use; set the ball milling speed to 350 r / min and the ball milling time to 9 hours;

[0043] The chemical composition of the clay is: Al2O3 content ≥35.0wt%, SiO2 content ≥50.0wt%, K2O content ≤1.5wt%; and the particle size of the clay is ≤0.088mm;

[0044] Step 3: Put the dried raw materials in step 1 into a high-speed mixer, add zinc stearate with a mass of 0.8% of the total mass of the raw materials, and mix at a speed of 1200 r / min for 40 minutes; add a binder and continue stirring for 20 minutes, then add a water-based binder to the obtained mixed solid material at a dosage ratio of 0.08 mL / g, mix well, and age for 20 hours to form a blank; inject the blank into an isostatic pressing device with a microchannel mold for stamping;

[0045] The binder is prepared by mixing silicon dioxide, boron oxide, and potassium oxide in a weight ratio of 2.5:1.5:1. The pressure during stamping is set to 180 MPa, and the holding time is set to 15 minutes. The water-based binder is a polyvinyl alcohol aqueous solution with a concentration of 6 wt%.

[0046] Step 4: Dry the formed green body at 45°C for 15 hours and then at 85°C for 9 hours. After drying, transfer it to a degreasing furnace and increase the furnace temperature to 550°C at a rate of 2°C / min. Keep it at this temperature for 3 hours for degreasing.

[0047] Step 5: Transfer the degreased green body into a high-temperature sintering furnace, raise the furnace temperature to 1500°C at a rate of 5°C / min, and heat-seal for 5 hours before cooling in the furnace to obtain a sagger base;

[0048] Step 6: Immerse the sagger base in the protective slurry for 10 minutes, take it out and dry it at 90°C for 4 hours; then transfer it to a high-temperature furnace and raise the furnace temperature to 1350°C at a rate of 4°C / min. After heat preservation and curing for 4 hours, the sagger containing the positive electrode material is obtained.

[0049] Example 3

[0050] A method for preparing a sagger for holding positive electrode materials comprises the following steps:

[0051] Step 1: Weigh 30 parts of cordierite, 15 parts of mullite, 10 parts of spodumene, 10 parts of boron nitride, 6 parts of silicon carbide, 10 parts of zirconium oxide, and 2.5 parts of a binder by weight; and dry all the raw materials except the binder and store them for future use;

[0052] The particle size of boron nitride, silicon carbide and zirconium oxide is 0.03 mm; the particle size of cordierite, mullite and spodumene is 0.08 mm; the drying temperature of cordierite, mullite, spodumene, boron nitride and silicon carbide is 120°C and the drying time is 6 hours; when drying zirconium oxide, a vacuum drying process is adopted, and the drying temperature is set to 90°C, the drying time is 3 hours, and the vacuum degree is 0.01 MPa;

[0053] Step 2: Weigh 55 parts of corundum, 20 parts of spinel, 10 parts of clay, 5 parts of chromium carbide, and 10 parts of titanium nitride, respectively, by weight; put all the raw materials into a grinding device together; after grinding, add 6 parts of cerium dioxide powder to the obtained mixed powder, mix well, and then transfer to a ball mill jar, control the ball-to-material ratio to 10:1, add anhydrous ethanol, and after ball milling, store the obtained protective coating for future use; set the ball milling speed to 400 r / min and the ball milling time to 10 hours;

[0054] The chemical composition of the clay is: Al2O3 content ≥35.0wt%, SiO2 content ≥50.0wt%, K2O content ≤1.5wt%; and the particle size of the clay is ≤0.088mm;

[0055] Step 3: Put the dried raw materials in step 1 into a high-speed mixer, add zinc stearate with a mass of 1.0% of the total mass of the raw materials, and mix at a speed of 1200 r / min for 50 minutes; add a binder and continue stirring for 25 minutes, then add a water-based binder to the obtained mixed solid material at a dosage ratio of 0.1 mL / g, mix well, and age for 24 hours to form a blank; inject the blank into an isostatic pressing device with a microchannel mold for stamping;

[0056] The binder is prepared by mixing silicon dioxide, boron oxide, and potassium oxide in a weight ratio of 3:2:1. The pressure during stamping is set to 200 MPa, and the holding time is set to 20 minutes. The water-based binder is a polyvinyl alcohol aqueous solution with a concentration of 8 wt%.

[0057] Step 4: Dry the formed green body at 50°C for 12 hours and then at 90°C for 8 hours. After drying, transfer it to a degreasing furnace and increase the furnace temperature to 600°C at a rate of 2°C / min. Keep it at this temperature for 2 hours for degreasing.

[0058] Step 5: The degreased green body is transferred to a high-temperature sintering furnace, and the furnace temperature is raised to 1600°C at a rate of 6°C / min. After heat preservation for 4 hours, the green body is cooled in the furnace to obtain a sagger base;

[0059] Step 6: Immerse the sagger base in the protective slurry for 15 minutes, take it out and dry it at 95°C for 3 hours; then transfer it to a high-temperature furnace and raise the furnace temperature to 1380°C at a rate of 5°C / min. After heat preservation and curing for 3 hours, the sagger containing the positive electrode material is obtained.

[0060] Comparative Example: This comparative example differs from Example 1 in that titanium nitride is not used in the protective coating.

[0061] Performance test: The relevant performances of the sagger samples provided in Examples 1 to 3 and the comparative example were tested respectively, and the obtained test data were recorded in the following table:

[0062]

[0063] Note: 1. Oxidation weight gain test: The sagger samples provided in Examples 1 to 3 and the comparative example were placed in a muffle furnace, oxidized in air at 1400°C for 100 hours, naturally cooled to room temperature, and then taken out and weighed to calculate the weight gain of each group of saggers after oxidation treatment.

[0064] 2. Friction coefficient test: The wear resistance of the sagger samples provided in Examples 1 to 3 and the comparative example was tested using a pin-on-disc wear tester; the test load was 10 N, the speed was set to 200 r / min, and the test time was 60 min.

[0065] By comparing and analyzing the relevant data in the table, it can be seen that the sagger prepared by the present invention not only has excellent high temperature resistance and corrosion resistance, but also has outstanding thermal shock stability and wear resistance. While effectively ensuring the service life of the sagger, it also improves the sintering quality of the positive electrode material and ensures its quality. This shows that the sagger for holding positive electrode materials and the preparation method provided by the present invention have a broader market prospect and are more suitable for promotion.

[0066] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0067] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a sagger for holding positive electrode materials, characterized in that: The following steps are involved: Step 1: Weigh 20 to 30 parts of cordierite, 10 to 15 parts of mullite, 6 to 10 parts of spodumene, 5 to 10 parts of boron nitride, 3 to 6 parts of silicon carbide, 5 to 10 parts of zirconium oxide, and 1.5 to 2.5 parts of a binder by weight; and dry all the raw materials except the binder and store them for future use; Step 2: Weigh 45-55 parts of corundum, 15-20 parts of spinel, 6-10 parts of clay, 3-5 parts of chromium carbide, and 6-10 parts of titanium nitride, respectively, by weight; put all the raw materials into a grinding device; after grinding, add 3-6 parts of cerium dioxide powder to the resulting mixed powder, mix well, transfer to a ball mill, add anhydrous ethanol, and after ball milling, store the resulting protective coating for future use; Step 3: Forming embryos from the raw materials dried in step 1; Step 4: Dry the green body at 40-50°C for 12-15 hours, and then at 80-90°C for 8-10 hours; After drying is completed, it is transferred to a degreasing furnace for degreasing; Step 5: Transfer the degreased green body into a high-temperature sintering furnace, and raise the furnace temperature to 1400-1600°C at a rate of 4-6°C / min. After heat preservation for 4-6 hours, cool it in the furnace to obtain a sagger base; Step 6: Immerse the sagger base in the protective slurry for 10 to 15 minutes, take it out and dry it, then transfer it to a high-temperature furnace for high-temperature curing. After curing is completed, the sagger containing the positive electrode material is obtained.

2. The method for preparing a sagger for holding positive electrode materials according to claim 1, wherein the specific method for preparing the embryo body in step 3 is as follows: putting the dried raw materials in step 1 into a high-speed mixer, adding zinc stearate with a mass of 0.5-1.0% of the total mass of the raw materials, and mixing at a speed of 1000-1200 r / min for 30-50 min; adding a binder and continuing stirring for 15-25 min, and then adding a water-based binder to the obtained mixed solid material at a dosage ratio of 0.06-0.1 mL / g, mixing and aging for 15-24 hours to form a blank; injecting the blank into an isostatic pressing device with a microchannel mold for stamping to obtain an embryo body.

3. The method for preparing a sagger for holding positive electrode materials according to claim 1, characterized in that: In the step 1, the particle size of boron nitride, silicon carbide and zirconium oxide is 0.01 to 0.03 mm; the particle size of cordierite, mullite and spodumene is 0.04 to 0.08 mm; and the drying temperature of cordierite, mullite, spodumene, boron nitride and silicon carbide is 100 to 120° C., and the drying time is 6 to 8 hours; when drying zirconium oxide, a vacuum drying process is adopted, the drying temperature is set to 80 to 90° C., the drying time is 3 to 5 hours, and the vacuum degree is 0.01 MPa.

4. The method for preparing a sagger for holding positive electrode materials according to claim 1, characterized in that: The specific process of degreasing in step 4 is as follows: the dried green body is transferred to a degreasing furnace, the furnace temperature is raised to 500-600°C at a rate of 1-2°C / min, and the temperature is kept at this temperature for 2-3 hours for degreasing.

5. The method for preparing a sagger for holding positive electrode materials according to claim 1, characterized in that: In step 2, the rotation speed during ball milling is set to 300-400 r / min, and the ball milling time is 8-10 h.

6. The method for preparing a sagger for holding positive electrode materials according to claim 1, characterized in that: The binder is prepared by mixing silicon dioxide, boron oxide and potassium oxide in a weight ratio of 2 to 3:1 to 2:

1.

7. The method for preparing a sagger for holding positive electrode materials according to claim 1, characterized in that: The specific process of high temperature curing in step six is: raising the temperature of the high temperature furnace to 1300-1380° C. at a rate of 3-5° C. / min, and curing at this temperature for 3-5 hours.

8. The method for preparing a sagger for holding positive electrode materials according to claim 1, characterized in that: In step 3, the pressure during stamping is set to 150-200 MPa, and the holding time is set to 15-20 minutes.

9. The method for preparing a sagger for containing positive electrode materials according to claim 1, characterized in that: The water-based binder in step three is a polyvinyl alcohol aqueous solution with a concentration of 5-8 wt%.

10. A sagger for containing positive electrode materials, characterized in that: The sagger for holding the positive electrode material is prepared according to the method for preparing a sagger for holding the positive electrode material according to any one of claims 1 to 9.

Images