A kind of sodium-ion battery anode material sintering kiln car and its preparation method

Abstract

The application discloses a sagger for sintering of sodium ion battery positive electrode materials and a preparation method thereof, and relates to the technical field of sagger preparation. The sagger for sintering of sodium ion battery positive electrode materials prepared by the application comprises a base layer and a surface coating slurry, the base layer is obtained by mixing and pressing mullite, alumina, cordierite and modified refractory material, the surface coating slurry is obtained by mixing strontium carbonate, modified alumina, silicon carbide and silicon nitride, the base layer is immersed in the surface coating slurry, and then drying and high-temperature sintering are performed to obtain the sagger for sintering of sodium ion battery positive electrode materials. The sagger for sintering of sodium ion battery positive electrode materials prepared by the application has good mechanical properties and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of saggar preparation, in particular to a saggar for sintering sodium-ion battery positive electrode materials and a preparation method thereof. BACKGROUND

[0002] The saggar for sintering sodium-ion battery positive electrode materials is a container or mold specially used in the sintering process of sodium-ion battery positive electrode materials. Its main function is to load positive electrode material powder and provide necessary protection and support in the sintering furnace to ensure that the positive electrode material can be uniformly and efficiently sintered.

[0003] The saggar is usually made of high-temperature-resistant and corrosion-resistant materials that can withstand high-temperature pressure and chemical corrosion while having good thermal conductivity and electrical insulation. Specifically, the commonly used materials for the saggar include ceramic materials such as alumina (Al2O3) and silicon carbide (SiC). These materials have high purity, high strength, high hardness, and high thermal stability, making them ideal choices for making saggars.

[0004] The manufacturing process of the saggar usually includes the following steps: first, select appropriate ceramic materials as the base according to the required size and shape; then, process the materials into the shape of the saggar through forming processes such as pressing or injection molding; next, perform sintering treatment at high temperatures to make the saggar have certain strength and stability; finally, perform finishing and detection to ensure that it meets the use requirements.

[0005] However, the traditional saggar for sintering sodium-ion battery positive electrode materials also has some drawbacks. For example, the interface reaction between the saggar and the positive electrode material may affect the performance of the material; the saggar may undergo slight deformation at high temperatures, causing cracks or deformation in the sintered material; in addition, repeated use of the saggar may cause surface wear and contamination, affecting the sintering effect. Therefore, when preparing the saggar, these drawbacks need to be considered and appropriate measures need to be taken to improve and optimize it. SUMMARY

[0006] The present application aims to provide a saggar for sintering sodium-ion battery positive electrode materials and a preparation method thereof to solve the problems in the prior art.

[0007] In order to solve the above technical problems, the present application provides the following technical solutions:

[0008] A saggar for sintering sodium-ion battery positive electrode materials, wherein the saggar is prepared by immersing a base layer in a surface coating slurry, followed by drying and high-temperature sintering.

[0009] Preferably, the substrate layer is obtained by mixing and pressing mullite, alumina, cordierite and modified refractory material; the modified refractory material is obtained by mixing magnesium calcium sand, magnesite, ultra-fine flake graphite and modified carbon nanotubes; the modified carbon nanotubes are obtained by reacting carbon nanotubes and ferric nitrate.

[0010] Preferably, the surface coating slurry is obtained by mixing strontium carbonate, modified alumina, silicon carbide and silicon nitride; the modified alumina is obtained by reacting alumina hollow microspheres and zirconium butoxide.

[0011] A preparation method of a sagger for sintering a positive electrode material of a sodium ion battery, comprising the following preparation steps:

[0012] (1) carbon nanotubes and 0.2 mol / L ferric nitrate solution are weighed according to a mass ratio of 1:30, carbon nanotubes and 98 wt% concentrated hydrochloric acid are mixed according to a mass ratio of 1:20, and then the mixture is heated to 100 DEG C and reacted for 4 h; after the reaction is completed, the mixture is filtered and dispersed into the 0.2 mol / L ferric nitrate solution, 28 wt% ammonia water is used to adjust the pH to 10, the mixture is filtered and washed with pure water for 3 times, and then the mixture is dried at 105 DEG C and calcined at 450 DEG C for 2 h to obtain modified carbon nanotubes;

[0013] (2) ultra-fine flake graphite, modified carbon nanotubes, magnesite, a binder and magnesium calcium sand are weighed; the ultra-fine flake graphite and the modified carbon nanotubes are ball milled for 1 h to obtain a premixed fine powder; then the magnesium calcium sand and the magnesite are added into a mixing mill, and then 50% of the binder is added for mixing and grinding; then the premixed fine powder and the remaining binder are added, and the mixture is mixed and ground uniformly, and then the mixture is cured at 220 DEG C for 12 h to obtain the refractory material;

[0014] (3) 30-40 parts of mullite, 20-25 parts of cordierite, 10-12 parts of sintered alumina powder, 5-7 parts of active alumina powder, 8-12 parts of the refractory material, 2-5 parts of yellow dextrin and 5-7 parts of pure water are uniformly mixed according to the mass fraction, and then the mixture is mixed for 20 min by using a wet mill; a single-column hydraulic press is used to press the mixture into a green body with a size of 25 mm*25 mm*125 mm under a pressure of 150 MPa; the green body is placed in a heat preservation furnace at 60 DEG C for 6 h, and then the green body is placed in a heat preservation furnace at 110 DEG C for 24 h; and then the substrate layer is obtained;

[0015] (4) alumina hollow microspheres, ethanol, zirconium butoxide and 2 mol / L acetic acid solution are weighed according to a mass ratio of 1:20:1.5:2; the alumina hollow microspheres and the ethanol are mixed and ultrasonically treated for 10 min; the zirconium butoxide is added and stirred; the 2 mol / L acetic acid solution is added and stirred for 2 h; the mixture is allowed to stand for 2 h; the mixture is filtered and dried; and then the mixture is treated at 1100 DEG C for 5 h to obtain modified alumina;

[0016] (5) 5-10 parts of strontium carbonate, 8-12 parts of modified alumina, 20-30 parts of silicon carbide powder, 10-20 parts of silicon nitride powder, 4-6 parts of carboxymethyl cellulose are added into 50-60 parts of pure water, and ball milling is carried out for 60-80 min, then 10-12 parts of pure water is added and stirred uniformly to obtain a surface coating slurry;

[0017] (6) the substrate layer is immersed in the surface coating slurry, and then taken out, the thickness of the slurry is 0.1-0.2 mm, and then drying and sintering are carried out to obtain a sagger for sintering of a positive electrode material of a sodium ion battery.

[0018] Preferably, the carbon nanotubes in step (1) are single-walled carbon nanotubes with a diameter of 60-100 nm and a length of 5-20 μm.

[0019] Preferably, the mass ratio of the superfine flake graphite, modified carbon nanotubes, magnesia, binder and magnesia-calcium sand in step (2) is 1.5:(1.5-2.0):35:3.5:70.

[0020] Preferably, the particle size of the superfine flake graphite in step (2) is 6-14 μm, the particle size of the magnesia is <0.088 mm, the type of the binder is phenolic resin FRJ-551, and the magnesia-calcium sand is obtained by mixing magnesia-calcium sand with a particle size of 0-1 mm, magnesia-calcium sand with a particle size of 1-3 mm and magnesia-calcium sand with a particle size of 3-5 mm at a mass ratio of 2:3:2.

[0021] Preferably, the particle size of the mullite in step (3) is 200 mesh, the particle size of the cordierite is 0.3-2.5 mm, the type of the sintered alumina is T60, which is purchased from Anmai Aluminum Industry (Qingdao) Co., Ltd., and the type of the activated alumina is CL370, which is purchased from Anmai Aluminum Industry (Qingdao) Co., Ltd.

[0022] Preferably, the particle size of the alumina hollow microspheres in step (4) is 1.3 μm, which is purchased from Kaifeng Gaolu Furnace Material Co., Ltd.

[0023] Preferably, the particle size of the silicon carbide powder in step (5) is 0.3-0.5 μm, and the type of the silicon nitride powder is SN-E10, which is purchased from Japan Ub.

[0024] Preferably, the drying temperature in step (6) is 80-90 ℃, and the drying time is 12-16 h; the sintering temperature is 1200 ℃, and the sintering time is 4-5 h.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] The sintering saggar for sodium ion battery positive electrode material prepared by the application comprises a base layer and a surface coating slurry, the base layer is obtained by mixing mullite, alumina, cordierite and modified refractory material, the surface coating slurry is obtained by mixing strontium carbonate, modified alumina, silicon carbide and silicon nitride, the base layer is immersed in the surface coating slurry, and then drying and high-temperature sintering are performed to obtain the sintering saggar for sodium ion battery positive electrode material.

[0027] Firstly, the modified carbon nanotube is prepared by reacting carbon nanotube and ferric nitrate, the modified refractory material is prepared by mixing magnesium calcium sand, magnesia, ultra-fine flake graphite and the modified carbon nanotube in the presence of a binding agent; the magnesium calcium carbon material is obtained by using carbon nanotube as a carbon source and magnesium calcium; the magnesium calcium material is a kind of alkaline refractory material, has high corrosion resistance in an alkaline environment, high density and excellent refractory performance; however, the strength of the magnesium calcium material is not high and the magnesium calcium material is easy to hydrate; the modified carbon nanotube obtained by reacting carbon nanotube and ferric nitrate contains uniformly distributed iron oxide on the surface and inside; the carbon nanotube can improve the mechanical properties of the magnesium calcium material; the iron oxide can not only act as a catalyst to make the phenolic resin binder form stable crystalline carbon during high-temperature carbonization, thereby further improving the mechanical properties, but also increase liquid phase sintering and improve the hydration resistance of the magnesium calcium material; mixing mullite, alumina, cordierite and modified refractory material can obtain the base layer with good mechanical properties.

[0028] Secondly, the alumina hollow microspheres coated with zirconia are obtained by reacting alumina hollow microspheres and zirconium butyl alcohol; the alumina hollow microspheres have the characteristics of light weight and hollow structure, which can provide good heat insulation performance, so that the saggar is protected from high-temperature damage when used in a high-temperature environment, thereby prolonging the service life of the saggar; however, the strength of the alumina hollow microspheres is low, and the alumina hollow microspheres are easy to be damaged during pressing and even mixing; the alumina hollow microspheres are coated with a layer of high-strength zirconia by reacting the alumina hollow microspheres and zirconium butyl alcohol, which can not only improve the strength of the hollow microspheres, but also enhance the corrosion resistance of the saggar due to the strong corrosion resistance of zirconia; then, the surface coating slurry is obtained by mixing strontium carbonate, modified alumina, silicon carbide and silicon nitride.

[0029] Finally, the base layer is immersed in the surface coating slurry, and then drying and high-temperature sintering are performed to obtain the sintering saggar for sodium ion battery positive electrode material; the addition of strontium carbonate and the reaction of strontium oxide generated during the sintering process with magnesium oxide, alumina and other components in the base layer generate a compound, which further develops into an interlocking structure; the appearance of the structure is conducive to enhancing the structure of the surface coating and the base layer, and the structure is not easy to fall off during use; the addition of silicon carbide and silicon nitride can endow the saggar with good oxidation resistance; the silicon dioxide generated by the reaction of silicon and oxygen blocks the pores by forming a compound phase with magnesium oxide in the base layer, thereby preventing further oxidation of the material. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0031] The following is a list of materials in all the examples and comparative examples:

[0032] The carbon nanotubes are single-walled carbon nanotubes with a diameter of 60-100 nm and a length of 5-20 μm;

[0033] The ultra-fine flake graphite has a particle size of 6-14 μm;

[0034] The magnesia has a particle size of <0.088 mm;

[0035] The binder is a phenolic resin FRJ-551;

[0036] The magnesite-calcium sand is obtained by mixing magnesite-calcium sand with a particle size of 0-1 mm, magnesite-calcium sand with a particle size of 1-3 mm, and magnesite-calcium sand with a particle size of 3-5 mm at a mass ratio of 2:3:2;

[0037] The mullite has a particle size of 200 mesh;

[0038] The coptite has a particle size of 0.3-2.5 mm;

[0039] The sintered alumina is T60, purchased from Anmai Aluminum Industry (Qingdao) Co., Ltd.;

[0040] The activated alumina is CL370, purchased from Anmai Aluminum Industry (Qingdao) Co., Ltd.;

[0041] The alumina hollow microspheres have a particle size of 1.3 μm, purchased from Kaifeng Gaolu Furnace Material Co., Ltd.;

[0042] The silicon carbide powder has a particle size of 0.3-0.5 μm;

[0043] The silicon nitride powder is SN-E10, purchased from Japan Ubbe.

[0044] Example 1

[0045] A preparation method of a sagger for sintering a sodium ion battery cathode material, the preparation method of the sagger for sintering the sodium ion battery cathode material comprises the following preparation steps:

[0046] (1) Take carbon nanotubes and 0.2 mol / L iron nitrate solution by mass ratio 1:30, mix carbon nanotubes and 98wt% concentrated hydrochloric acid by mass ratio 1:20, heat to 100℃ for 4h, filter after reaction, disperse into 0.2 mol / L iron nitrate solution, adjust pH to 10 using 28wt% ammonia water, filter and wash 3 times with pure water, dry at 105℃, then calcine at 450℃ for 2h, to obtain modified carbon nanotubes.

[0047] (2) Take ultra-fine flake graphite, modified carbon nanotubes, magnesia, binder, magnesium-calcium sand by mass ratio 1.5:1.5:35:3.5:70; mix the ultra-fine flake graphite and modified carbon nanotubes uniformly by ball milling for 1h to obtain a premixed fine powder, then add the magnesium-calcium sand and magnesia into the mixing mill, then add 50% of the binder for mixing and milling, then add the premixed fine powder and the remaining binder, mix and mill uniformly, then solidify at 220℃ for 12h to obtain a refractory material.

[0048] (3) Take 30 parts of mullite, 20 parts of cordierite, 10 parts of sintered alumina powder, 5 parts of active alumina powder, 8 parts of refractory material, 2 parts of yellow dextrin and 5 parts of pure water by mass fraction, mix uniformly using a wet mill for 20min; use a single-column hydraulic press to press into a green body of 25mm*25mm*125mm under a pressure of 150MPa; place the green body in a heat preservation oven at 60℃ for 6h, then at 110℃ for 24h; to obtain a matrix layer.

[0049] (4) Take alumina hollow microspheres, ethanol, zirconium butoxide, 2mol / L acetic acid solution by mass ratio 1:20:1.5:2, mix the alumina hollow microspheres and ethanol, ultrasonic for 10min, add zirconium butoxide and continue to stir, then add 2mol / L acetic acid solution and continue to stir for 2h, then stand for 2h, filter and dry, then treat at 1100℃ for 5h to obtain modified alumina.

[0050] (5) Take 5 parts of strontium carbonate, 8 parts of modified alumina, 20 parts of silicon carbide powder, 10 parts of silicon nitride powder, 4 parts of carboxymethyl cellulose by mass fraction, add 50 parts of pure water and ball mill for 60min, then add 10 parts of pure water and stir uniformly to obtain a surface coating slurry.

[0051] (6) immerse the matrix layer in the surface coating slurry, then take it out, the thickness of the slurry is 0.2mm, then dry, the drying temperature is 80℃, the drying time is 12h; sinter, the sintering temperature is 1200℃, the sintering time is 5h, to obtain a sagger for sintering sodium ion battery cathode material.

[0052] Example 2:

[0053] The application discloses a preparation method of a sagger for sintering of a sodium ion battery positive electrode material.

[0054] (1) Carbon nanotubes and 0.2 mol / L iron nitrate solution are weighed according to a mass ratio of 1:30, the carbon nanotubes and 98 wt% concentrated hydrochloric acid are mixed according to a mass ratio of 1:20, and then the mixture is reacted at 100 DEG C for 4 hours; after the reaction, the mixture is filtered and dispersed into the 0.2 mol / L iron nitrate solution, 28 wt% ammonia water is used to adjust the pH to 10, the mixture is filtered and washed with pure water for three times, and then the mixture is dried at 105 DEG C and calcined at 450 DEG C for 2 hours to obtain modified carbon nanotubes.

[0055] (2) Superfine flake graphite, modified carbon nanotubes, magnesia, a binding agent and magnesium-calcium sand are weighed according to a mass ratio of 1.5:1.7:35:3.5:70; the superfine flake graphite and the modified carbon nanotubes are uniformly mixed by ball milling for 1 hour to obtain a premixed fine powder; then the magnesium-calcium sand and the magnesia are added into a mixing mill, and then 50% of the binding agent is added for mixing and grinding; then the premixed fine powder and the remaining binding agent are added, and the mixture is uniformly mixed and ground, and then the mixture is cured at 220 DEG C for 12 hours to obtain a refractory material.

[0056] (3) 35 parts of mullite, 22 parts of cordierite, 11 parts of sintered alumina powder, 6 parts of active alumina powder, 10 parts of the refractory material, 3 parts of yellow dextrin and 6 parts of pure water are uniformly mixed according to mass fractions, and then the mixture is mixed by using a wet mill for 20 minutes; a single-column hydraulic machine is used to press the mixture into a green body with a size of 25 mm*25 mm*125 mm under a pressure of 150 MPa; the green body is placed in a heat preservation furnace at 60 DEG C for 6 hours, and then the green body is placed in a heat preservation furnace at 110 DEG C for 24 hours; and thus a matrix layer is obtained.

[0057] (4) Alumina hollow microspheres, ethanol, zirconium butoxide and 2 mol / L acetic acid solution are weighed according to a mass ratio of 1:20:1.5:2; the alumina hollow microspheres and the ethanol are mixed and ultrasonically treated for 10 minutes; zirconium butoxide is added and stirred; 2 mol / L acetic acid solution is added and stirred for 2 hours; the mixture is then placed for 2 hours; the mixture is filtered and dried; and the mixture is treated at 1100 DEG C for 5 hours to obtain modified alumina.

[0058] (5) According to mass fractions, 7 parts of strontium carbonate, 10 parts of modified alumina, 25 parts of silicon carbide powder, 15 parts of silicon nitride powder and 5 parts of carboxymethyl cellulose are added into 55 parts of pure water and ball milled for 70 minutes; 11 parts of pure water is added and stirred uniformly to obtain a surface coating slurry.

[0059] (6) The matrix layer is immersed in the surface coating slurry and then taken out, the thickness of the slurry solution is 0.15 mm, and then the matrix layer is dried at a drying temperature of 85 DEG C for 15 hours; and then the matrix layer is sintered at a sintering temperature of 1200 DEG C for 4.5 hours to obtain the sagger for sintering of the sodium ion battery positive electrode material.

[0060] Example 3:

[0061] The application discloses a preparation method of a sagger for sintering of a sodium ion battery positive electrode material.

[0062] (1) carbon nanotubes and 0.2 mol / L iron nitrate solution are weighed according to a mass ratio of 1:30, the carbon nanotubes and 98 wt% concentrated hydrochloric acid are mixed according to a mass ratio of 1:20, and then the mixture is reacted at 100 DEG C for 4 hours; after the reaction is completed, the mixture is filtered and dispersed into the 0.2 mol / L iron nitrate solution, 28 wt% ammonia water is used to adjust the pH to 10, the mixture is filtered and washed with pure water for three times, and then the mixture is dried at 105 DEG C and calcined at 450 DEG C for 2 hours to obtain modified carbon nanotubes.

[0063] (2) superfine flake graphite, modified carbon nanotubes, magnesia, a binding agent and magnesium-calcium sand are weighed according to a mass ratio of 1.5:2.0:35:3.5:70; the superfine flake graphite and the modified carbon nanotubes are uniformly mixed by ball milling for 1 hour to obtain a premixed fine powder; then the magnesium-calcium sand and the magnesia are added into a mixing mill, and then 50% of the binding agent is added for mixing and grinding; then the premixed fine powder and the remaining binding agent are added, and the mixture is uniformly mixed and ground, and then the mixture is cured at 220 DEG C for 12 hours to obtain a refractory material.

[0064] (3) 40 parts of mullite, 25 parts of cordierite, 12 parts of sintered alumina powder, 7 parts of active alumina powder, 12 parts of the refractory material, 5 parts of yellow dextrin and 7 parts of pure water are uniformly mixed according to mass fractions, and then the mixture is mixed by using a wet mill for 20 minutes; a single-column hydraulic machine is used to press the mixture into a green body with a size of 25mm*25mm*125mm under a pressure of 150MPa; the green body is placed in a heat preservation furnace at 60 DEG C for 6 hours, and then the green body is placed in a heat preservation furnace at 110 DEG C for 24 hours; and thus a matrix layer is obtained.

[0065] (4) alumina hollow microspheres, ethanol, zirconium butoxide and 2 mol / L acetic acid solution are weighed according to a mass ratio of 1:20:1.5:2; the alumina hollow microspheres and the ethanol are mixed and ultrasonically treated for 10 minutes; the zirconium butoxide is added and stirred; the 2 mol / L acetic acid solution is added and stirred for 2 hours; the mixture is left to stand for 2 hours; the mixture is filtered and dried; and the mixture is treated at 1100 DEG C for 5 hours to obtain modified alumina.

[0066] (5) 10 parts of strontium carbonate, 12 parts of the modified alumina, 30 parts of silicon carbide powder, 20 parts of silicon nitride powder and 6 parts of carboxymethyl cellulose are ball milled in 60 parts of pure water for 60 minutes, and then 12 parts of pure water is added and stirred uniformly to obtain a surface coating slurry.

[0067] (6) the substrate layer is immersed in the surface coating slurry and then taken out, the thickness of the slurry solution is 0.1 mm, and then dried at a drying temperature of 80 ℃ for 12 h; sintered at a sintering temperature of 1200 ℃ for 4 h to obtain the sodium-ion battery positive electrode material sintering saggar.

[0068] Comparative Example 1:

[0069] The preparation method of the sodium-ion battery positive electrode material sintering saggar of Comparative Example 1 is different from that of Example 2 in that step (1) is not performed, and step (2) is modified as follows: the ultra-fine flake graphite, magnesia, binder, and magnesium-calcium sand are weighed according to a mass ratio of 1.5:35:3.5:70; the ultra-fine flake graphite is ball milled for 1 h to obtain a premixed fine powder, then the magnesium-calcium sand and magnesia are added to a mixing mill, and then 50% of the binder is added for mixing and milling, then the premixed fine powder and the remaining binder are added, and after mixing and milling, the refractory material is obtained by curing at 220 ℃ for 12 h.

[0070] Comparative Example 2:

[0071] The preparation method of the sodium-ion battery positive electrode material sintering saggar of Comparative Example 2 is different from that of Example 2 in that steps (4) to (5) are not included, and step (6) is modified as follows: the substrate is dried at a drying temperature of 85 ℃ for 15 h; sintered at a sintering temperature of 1200 ℃ for 4-5 h to obtain the sodium-ion battery positive electrode material sintering saggar.

[0072] Test Example 1:

[0073] Mechanical property test: the high-temperature bending strength of the saggar was tested according to GB / T 5072-2023, at a temperature of 1100 ℃ for 60 min. The results are shown in Table 1.

[0074] Table 1: Statistical results of mechanical property test

[0075] High temperature flexural strength / MPa High temperature flexural strength / MPa Example 1 14.01 Comparative Example 1 10.31 Example 2 15.34 Comparative Example 2 9.74 Example 3 15.97

[0076] From the experimental data of Examples 1-3 and Comparative Examples 1-2 in Table 1, it can be found that the sodium-ion battery positive electrode material sintering saggar prepared by the present application has good mechanical properties.

[0077] By comparing the data in the table, the mechanical properties of the examples are better than those of the comparative examples, which shows that the modified carbon nanotubes are prepared by reacting carbon nanotubes and ferric nitrate, the modified refractory material is prepared by mixing magnesium calcium sand, magnesia, ultra-fine flake graphite and the modified carbon nanotubes in the presence of a binder; the carbon nanotubes are used as a carbon source and magnesium calcium to obtain a magnesium calcium carbon material, the strength of the magnesium calcium material is not high, and the magnesium calcium material is easy to hydrate, the modified carbon nanotubes prepared by reacting carbon nanotubes and ferric nitrate contain uniformly distributed iron oxide on the surface and inside, the carbon nanotubes can improve the mechanical properties of the magnesium calcium material, and the iron oxide can not only be used as a catalyst to make the phenolic resin binder form stable crystalline carbon during high-temperature carbonization, further improving the mechanical properties, but also increase liquid phase sintering, improve the hydration resistance of the magnesium calcium material, and promote the densification of the magnesium calcium material.

[0078] Test Example 2:

[0079] Anti-erosion performance test: sodium manganate positive electrode material is used for anti-erosion test. Sodium carbonate and manganese carbonate are weighed according to n(Na):n(Mn) = 1:1, and the positive electrode material precursor is obtained after mixing uniformly. The mass of the precursor is 0.5 times the mass of the sagger, which is placed on the surface of the sagger, and the sagger is calcined at 1100℃ for 36h for erosion reaction, and the surface condition of the sagger is recorded. The results are shown in Table 2.

[0080] Table 2 Anti-erosion performance test statistical results

[0081] Skull condition Skull condition Example 1 Sound Comparative Example 1 Cracked Example 2 Sound Comparative Example 2 Cracked Example 3 Sound

[0082] From the experimental data comparison of examples 1-3 and comparative examples 1-3 in Table 2, it can be found that the sagger for sintering of the positive electrode material of the sodium ion battery prepared by the present application has excellent anti-erosion performance.

[0083] By comparing the data in the table, the anti-erosion ability of the examples is better than that of the comparative examples, which shows that the alumina hollow microspheres coated with zirconium oxide on the surface are obtained by reacting alumina hollow microspheres and zirconium butanol; the strong corrosion resistance of zirconium oxide can enhance the anti-erosion performance of the sagger.

[0084] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a saggar for sintering of a sodium-ion battery cathode material, characterized in that, The preparation steps include: (1) carbon nanotubes, 0.2 mol / L iron nitrate solution are weighed according to the mass ratio of 1:30, carbon nanotubes and 98wt% concentrated hydrochloric acid are mixed according to the mass ratio of 1:20, and the mixture is reacted at 100°C for 4h. After the reaction is completed, it is filtered and dispersed into 0.2 mol / L iron nitrate solution, 28wt% ammonia water is used to adjust the pH to 10, and then it is filtered and washed with pure water for 3 times. After drying at 105°C, it is calcined at 450°C for 2h to obtain modified carbon nanotubes; (2) superfine flake graphite, modified carbon nanotubes, magnesia, binder, and magnesia-calcium sand are weighed according to the mass ratio of 1.5:(1.5-2.0):35:3.5:

70. The superfine flake graphite and the modified carbon nanotubes are uniformly mixed by ball milling for 1h to obtain a premixed fine powder. Then, the magnesia-calcium sand and the magnesia are added into a mixing mill, and then 50% of the binder is added for mixing. Then, the premixed fine powder and the remaining binder are added, and after uniform mixing, it is cured at 220°C for 12h to obtain a refractory material; (3) 30-40 parts of mullite, 20-25 parts of cordierite, 10-12 parts of sintered alumina powder, 5-7 parts of active alumina powder, 8-12 parts of refractory material, 2-5 parts of yellow dextrin, and 5-7 parts of pure water are uniformly mixed, and a wet mill is used for mixing for 20min; a single-column hydraulic press is used to press into a green body with a size of 25mm*25mm*125mm under a pressure of 150MPa; the green body is placed in a 60°C incubator for 6h, and then incubated at 110°C for 24h to obtain a matrix layer; (4) alumina hollow microspheres, ethanol, zirconium butoxide, and 2mol / L acetic acid solution are weighed according to the mass ratio of 1:20:1.5:

2. The alumina hollow microspheres and the ethanol are mixed and ultrasonically treated for 10min. Then, the zirconium butoxide is added and stirred, and then the 2mol / L acetic acid solution is added and stirred for 2h. After standing for 2h, it is filtered and dried, and then treated at 1100°C for 5h to obtain modified alumina; (5) 5-10 parts of strontium carbonate, 8-12 parts of modified alumina, 20-30 parts of silicon carbide powder, 10-20 parts of silicon nitride powder, 4-6 parts of carboxymethyl cellulose, and 50-60 parts of pure water are ball milled for 60-80min. Then, 10-12 parts of pure water is added and stirred uniformly to obtain a surface coating slurry; (6) the matrix layer is immersed in the surface coating slurry and then taken out, and the thickness of the slurry is 0.1-0.2mm. After drying and sintering, a sagger for sintering sodium ion battery cathode material is obtained.

2. The preparation method of the sagger for sintering sodium-ion battery positive electrode material according to claim 1, characterized in that, In step (1), the carbon nanotubes are single-walled carbon nanotubes with a diameter of 60-100nm and a length of 5-20μm.

3. The preparation method of the sagger for sintering sodium-ion battery positive electrode material according to claim 1, characterized in that, In step (2), the particle size of the superfine flake graphite is 6-14μm; the particle size of the magnesia is <0.088mm; the type of the binder is phenolic resin FRJ-551; and the magnesia-calcium sand is obtained by mixing magnesia-calcium sand with a particle size of 0-1mm, magnesia-calcium sand with a particle size of 1-3mm, and magnesia-calcium sand with a particle size of 3-5mm according to the mass ratio of 2:3:

2.

4. The preparation method of the sagger for sintering sodium-ion battery positive electrode material according to claim 1, characterized in that, The particle size of the mullite in the step (3) is 200 mesh; the particle size of the cordierite is 0.3-2.5 mm; the type of the sintered alumina is T60; the type of the activated alumina is CL370.

5. The preparation method of the sintering pot for sodium-ion battery cathode material according to claim 1, characterized in that, The particle size of the alumina hollow microspheres in the step (4) is 1.3 μm.

6. The preparation method of the sintering saggar for sodium-ion battery cathode material according to claim 1, characterized in that, The particle size of the silicon carbide powder in the step (5) is 0.3-0.5 μm; the type of the silicon nitride powder is SN-E10.

7. The preparation method of the sintering saggar for sodium-ion battery cathode material according to claim 1, characterized in that, The temperature of the drying in the step (6) is 80-90 ℃, and the drying time is 12-16 h; the temperature of the sintering is 1200 ℃, and the sintering time is 4-5 h. 8.A sagger for sintering a sodium-ion battery cathode material, which is prepared by the method according to any one of claims 1 to 7.