A lithium absorption-proof sagger for lithium cobalt oxide positive electrode sintering and preparation method thereof

Abstract

The present invention discloses a lithium-absorbing-proof sagger for sintering lithium cobalt oxide positive electrodes and a preparation method thereof. The specific steps of the preparation method are as follows: S1. Mixing potassium fluorozirconate solution and amorphous alumina to obtain a premix; S2. Heat-treating the premix, cooling with the furnace, and then grinding to obtain a pre-burned material; S3. Mixing calcium hexaaluminate particles, pre-burned material, fused magnesia fine powder, rare earth composite yttrium zirconium ceramic powder, and calcium dialumite fine powder to obtain a mixture; S4. Adding calcium lignin sulfonate solution to the mixture and stirring to obtain a green body material; S5. Pouring the green body material into a vibration molding, curing, demoulding, and drying to obtain a green sagger; S6. After heat-treating the green sagger, cooling with the furnace to room temperature, a lithium-absorbing-proof sagger for sintering lithium cobalt oxide positive electrodes is obtained. The process of the present invention is simple, and the prepared lithium-absorbing-proof sagger for sintering lithium cobalt oxide positive electrodes has good sintering performance, high strength, strong resistance to the corrosion and permeability of lithium cobalt components, high thermal shock stability, and low specific gravity.

Description

Technical Field

[0001] The present invention relates to the technical field of saggers, and in particular to a lithium absorption-proof sagger for sintering a lithium cobalt oxide positive electrode and a preparation method thereof. Background Art

[0002] LiCoO2 is an important type of lithium battery cathode material. In addition to its cycle performance and high specific capacity, its highlight is its high operating voltage ( Cheng Meixiao, Wan Guangcong, Shen Haipeng, et al. Research progress of high voltage lithium cobalt oxide batteries[J]. Power Technology, 2022，46(3)：226-229 ), so it is also called high voltage lithium cobalt oxide battery.

[0003] Lithium cobalt oxide is prepared by high-temperature solid-phase method using lithium carbonate and cobalt trioxide (or cobalt carbonate) as raw materials, which are calcined in sagger after high-energy planetary ball milling ( Xie Jianjun. On the development of high voltage lithium cobalt oxide cathode materials[J]. Science and Technology Information, 2023, 21(14): 44-47 ). Unlike other cathode materials (lithium iron phosphate, lithium manganese oxide, LNCM ternary), lithium cobalt oxide cathode has the most serious erosion on sagger due to its own composition characteristics, mainly due to the following reasons:

[0004] (1) The sintering temperature of lithium cobalt oxide positive electrode material is the highest. Lithium cobalt oxide is a typical binary compound ( Zhang Lifen, Wan Hong Qiang, Wang Fenggang, et al. Study on the erosion mechanism of sagger used in LiCoO2 sintering[J]. Mining and Metallurgical Engineering, 2023, 43(4): 144-146+ 153 During calcination, it is difficult for the large amount of liquid phase components to promote sintering, and it is also difficult to form a large number of lattice defects through complete solid solution reaction. Therefore, compared with the calcination of other cathode materials, it has the highest sintering temperature (approximately 1100°C). As a result, the saggers used in sintering lithium cobalt oxide cathode materials suffer the most severe corrosion and have a significantly shorter service life.

[0005] (2) Simultaneous erosion of lithium and cobalt components. During the solid-phase preparation of lithium cobalt oxide, the lithium source and cobalt source are dispersed mechanically and evenly. From a kinetic point of view, at high temperatures, the lithium and cobalt components will simultaneously corrode the sagger, causing the sagger to suffer double corrosion, which further reduces its service performance and life.

[0006] (3) Severe lithium loss leads to failure of the positive electrode material. The lithium and cobalt components undergo corrosion reactions at the interface with the sagger, but not synchronously. There are two reasons: first, the ion radius of lithium is much smaller than that of cobalt, and its penetration depth in the sagger is greater; second, the alkalinity of the lithium source is significantly stronger than that of the cobalt source, so the reaction between the lithium source and the sagger body continues ( Xie Huajing, Ren Yun, Xiao Guoqing, et al. Preparation and erosion mechanism of mullite-cordierite sagger[J]. Journal of the Chinese Ceramic Society, 2020, 38(6): 931-938), and the erosion and diffusion of cobalt can be weakened by forming a barrier. Therefore, the "lithium loss" phenomenon of lithium cobalt oxide positive electrode materials during the calcination process (especially when a brand new sagger is first loaded for calcination and service) is very serious, and even directly leads to the failure of the synthesis of lithium cobalt oxide. In other words, the lithium-cobalt ratio changes during the calcination process due to the asynchronous corrosion reaction, resulting in changes in the performance of the synthesized lithium cobalt oxide. In fact, related research work has also noticed the above problems. The widely used method is to increase the amount of lithium carbonate added before calcination (that is, to increase the lithium-cobalt ratio) to prevent the sagger from absorbing the lithium source and affecting the performance of the final synthesized lithium cobalt oxide, but this method has little effect. This is because the excessive increase in the content of the lithium source leads to a further increase in the alkalinity of the material (that is, an increase in the concentration difference of lithium between the positive electrode material and the sagger body), which accelerates the damage of the sagger.

[0007] (4) The toxicity of cobalt-containing components is obvious. The erosion of cobalt sources on saggers is also quite obvious. It is also toxic to the ecological environment and human health. It is also easy to volatilize at high temperatures. This leads to a higher toxicity risk in the recycling of saggers used for lithium cobalt oxide positive electrode sintering.

[0008] The patented technology, "A Preparation Method and Sagger for Lithium Cobalt Oxide Cathode Materials, CN201810376463.6," reports laying at least one layer of filter paper on the bottom of the sagger to prevent corrosion from the cathode material. The report also indicates that the mechanism by which the filter paper enhances corrosion of the sagger is unknown, but it is speculated to be due to the filter paper's barrier effect. However, at high temperatures, the filter paper burns out, leading to barrier failure. The service life of the sagger depends on the filter paper's function, which clearly contradicts the functional and longevity goals of the sagger.

[0009] The patented technology "Method for Preventing Sagger Corrosion During the Sintering of Lithium Cobalt Oxide, a Positive Electrode Material, CN201410631438.X" reports that before charging the lithium cobalt oxide sintering material, a 5-15mm thick layer of fine particles (mainly fine particles collected in the dust collector during the first and second sintering processes of the lithium cobalt oxide production process) is evenly laid in the sagger. Because the laid fine particles do not contain free lithium carbonate, the corrosion reaction rate between the fine particles and the sagger is reduced. However, the laid fine particles are constantly replaced and filled with the sagger as it is recycled. On the one hand, this affects the purity and quality of the positive electrode material, and on the other hand, the corrosion resistance of the sagger has not been effectively improved.

[0010] In addition, there are reports that ceramic materials made of magnesium aluminum spinel can form good corrosion resistance to lithium cobalt oxide positive electrode sintering ( Huang Hong, Huang Zhaohui, Fang Minghao, et al. Study on the corrosion of magnesia-alumina spinel ceramics during LiCoO2 synthesis[J]. Bulletin of Acid Salts, 2011, 30(3): 515-518), the main reason is that no free alumina or acidic silica components are introduced into the sagger raw material components, which avoids the reaction of lithium source with the sagger body to generate LiAlO2, eucryptite (Li2O-Al2O3-SiO2 system) and lithium silicate phases, which cause lithium loss. This has a good guide for the development of new saggers, but there are still three deficiencies: First, it fails to involve the thermal shock resistance of the sagger. The sagger is a carrier container used repeatedly. Magnesium aluminum spinel has certain advantages in resisting chemical erosion, but its thermal expansion coefficient is large, and the thermal shock resistance of the sagger will also seriously restrict its service life; second, magnesium aluminum spinel has a large specific gravity (density 3.58g / cm 3 ), using magnesium aluminum spinel as the main material will inevitably increase the weight of the sagger, which can easily cause damage to the rollers / rollers and other supporting materials of the positive electrode material sintering furnace, and also increase the development cost of the positive electrode material; thirdly, the porosity of ceramic or sagger products formed by semi-dry machine pressing is still relatively high, generally about 24% to 28%, which also leads to the inevitable erosion, penetration and damage of the ceramic / sagger products by the positive electrode material. Summary of the Invention

[0011] The object of the present invention is to address the above-mentioned deficiencies in the prior art and provide a lithium-absorbing-proof sagger for sintering a lithium cobalt oxide positive electrode and a preparation method thereof. The method is simple in process, and the prepared lithium-absorbing-proof sagger for sintering a lithium cobalt oxide positive electrode has good sintering performance, high strength, strong resistance to erosion and permeability of lithium cobalt components, high thermal shock stability, and low specific gravity.

[0012] The method for preparing a lithium-absorption-proof sagger for sintering a lithium cobalt oxide positive electrode of the present invention comprises the following specific steps:

[0013] S1. The potassium fluorozirconate solution and amorphous alumina are mixed to obtain a premix;

[0014] S2. The premix is heat treated and ground to obtain a pre-burned material after cooling in the furnace;

[0015] S3. The calcium hexaaluminate particles, pre-sintered material, fused magnesia powder, rare earth composite yttrium zirconium ceramic powder and calcium dialuminate powder were mixed to obtain a mixture;

[0016] S4. Calcium lignin sulfonate solution was added to the mixture and stirred to obtain a green body material;

[0017] S5. The green body material is poured into vibration molding, curing, demoulding, and curing to obtain green body in a sagger;

[0018] S6. After heat treatment, the sagger green body is cooled to room temperature along with the furnace to obtain a lithium absorption-proof sagger for sintering lithium cobalt oxide positive electrode.

[0019] Furthermore, the concentration of the potassium fluorozirconate solution is 2-4 mol / L; the mass ratio of the potassium fluorozirconate solution to the amorphous alumina is (12-15):100.

[0020] Furthermore, in step S2, the heat treatment is carried out at 700-800° C. for 2-3 hours.

[0021] Furthermore, the particle size of the pre-sintered material is ≤80 μm.

[0022] Furthermore, the mass ratio of the calcium hexaaluminate particles: pre-sintered material: fused magnesia fine powder: rare earth composite yttrium zirconium ceramic powder: calcium dialuminate fine powder is 100: (80-85): (10-12): (6-9): (20-28).

[0023] Furthermore, the calcium lignin sulfonate solution is prepared by stirring and mixing calcium lignin sulfonate and water in a mass ratio of (1-5):100 at 85-90° C.; and\or, the calcium lignin sulfonate solution accounts for 5.8-6.6 wt % of the mixture.

[0024] Furthermore, in step S5, the green body material is added into a mold, poured and vibrated, cured at 25-30° C. for 4-6 hours, and then demolded. The green body is dried at 100-120° C. for 3-5 hours to obtain a sagger green body.

[0025] Furthermore, in step S6, the heat treatment is to place the sagger green body at 1380-1410° C. and keep it warm for 4-6 hours.

[0026] Furthermore, the amorphous aluminum oxide is amorphous, has a particle size of 6 to 8 μm, and an Al 2 O 3 content of ≥99.5 wt %; and\or,

[0027] The particle size of the calcium hexaaluminate particles is 0.1 to 6 mm, wherein the mass ratio of [0.1 to 0.5 mm] particles: [1 to 2 mm] particles: [3 to 4 mm] particles: [5 to 6 mm] particles is (3 to 5): (25 to 30): (25 to 35): (6 to 8); and\or,

[0028] The fused magnesia fine powder has a particle size of 35 to 45 μm and a MgO content of ≥99 wt %; and / or the rare earth composite yttrium zirconium ceramic powder has a grade of YZ7.2ZLA, in accordance with GB / T31968-2015.

[0029] A lithium absorption-proof sagger for sintering a lithium cobalt oxide positive electrode prepared by the above-mentioned preparation method.

[0030] The beneficial effects of the present invention are:

[0031] (1) The preparation process of the present invention is simple, the raw materials are widely available and have stable performance, and no special equipment and processing methods are required. Combined with the pouring vibration process, no large-scale press equipment is required, which further simplifies the process and reduces the development cost of the sagger; the porosity of the sagger molding is greatly reduced, which is conducive to the densification of the sagger.

[0032] (2) The present invention pre-calcines amorphous alumina and potassium fluorozirconate to form a high-alkalinity solid solution-type potassium metaaluminate-potassium zirconate. This not only avoids the introduction of free alumina into the sagger components to absorb lithium-containing components, but also prevents the potassium salt from volatilizing and leaving pores that increase the porosity of the sagger. In addition, the amorphous nature of amorphous alumina is utilized to reduce the activation energy of sintering, achieve grain rearrangement and growth, and facilitate the acceleration of the solid solution reaction and the formation of the solid solution.

[0033] (3) The present invention takes alkali resistance as the starting point, uses high-alkalinity potassium, calcium, magnesium and other components as raw materials, and introduces no acidic silicon-containing components or free components, thereby increasing the alkalinity of the sagger material. At the same time, the higher thermodynamic stability of potassium aluminate solid solution is utilized to prevent the formation of LiAlO2, thereby preventing the absorption of lithium by the sagger and the loss of lithium from the positive electrode material.

[0034] (4) The present invention utilizes MgO to form a magnesium-cobalt continuous solid solution with cobalt-containing components at high temperature, which not only hinders the erosion of cobalt but also prevents the penetration and diffusion of cobalt through the solid solution layer. MgO does not react with lithium-containing components, thereby achieving the simultaneous resistance of the sagger to lithium and cobalt components.

[0035] (5) The present invention uses calcium hexaaluminate as the main raw material, utilizes its lamellar structure to form staggered layers, and combines it with the reasonable grading adjustment of the granular material to further reduce the penetration of lithium cobalt components; and calcium hexaaluminate has a low specific gravity and low porosity, which greatly reduces the volume density of the sagger and achieves lightweighting of the sagger.

[0036] (6) The present invention utilizes calcium lignin sulfonate ionization coating to control the hydration process of calcium dialumate, achieving uniform dispersion of the matrix components and enhancing the bonding strength between the particles and the matrix components. In addition, the rare earth composite component does not wet with lithium and cobalt, effectively preventing corrosion and penetration of the positive electrode material. Combined with the introduction of the low-expansion phase of calcium dialumate, it can not only provide good early strength for the sagger, but also improve the thermal shock resistance of the sagger, which is conducive to the longevity of the sagger.

[0037] The anti-lithium absorption sagger for sintering the lithium cobalt oxide positive electrode prepared by the present invention is tested:

[0038] (GB / T 2997-2015) Bulk density: 2.62~2.78g / cm 3 ;

[0039] (GB / T 2997-2015) apparent porosity: 14.6-15.2%;

[0040] (GB / T 2072-2008) compressive strength: 75-82 MPa;

[0041] (GB / T 30873-2014) 1100℃ thermal shock test: air rapid cooling method, number of cycles: 45 to 54 times;

[0042] (GB / T14983-2008) 1100℃×30h alkaline resistance test strength change rate is 2.1~2.4%. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a photograph of the appearance of the anti-lithium absorption sagger corrosion test for lithium cobalt oxide positive electrode sintering prepared in Example 1;

[0044] Figure 2 This is an SEM image of the anti-lithium absorption sagger corrosion test for the lithium cobalt oxide positive electrode sintering prepared in Example 1;

[0045] Figure 3 for Figure 2 A partial enlarged view of . DETAILED DESCRIPTION

[0046] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0047] Example 1

[0048] 1. A lithium cobalt oxide positive electrode sintering anti-lithium absorption sagger and its preparation method, the specific steps are as follows:

[0049] 1) adding potassium fluorozirconate solution to amorphous alumina in a mass ratio of 12:100 and mixing in a roller mixer for 15-20 minutes to obtain a premix;

[0050] The concentration of the potassium fluozirconate solution is 3 mol / L.

[0051] 2) keeping the premix at 800° C. for 2 hours, cooling it with the furnace, and grinding it to a particle size of ≤80 μm to obtain a pre-sintered material;

[0052] 3) adding calcium hexaaluminate particles: pre-calcined material: fused magnesia fine powder: rare earth composite yttrium zirconium ceramic powder: calcium dialuminate fine powder in a mass ratio of 100:85:10:6:20, adding the mixture to a blender and mixing for 15-25 minutes to obtain a mixture;

[0053] 4) adding a calcium lignin sulfonate solution accounting for 6.6 wt% of the mixture to the mixture, stirring for 8 to 10 minutes to obtain a green body;

[0054] The preparation process of the calcium lignin sulfonate solution is as follows: adding calcium lignin sulfonate to water at a mass ratio of 1:100 into a container, stirring at 85-90° C., and cooling to room temperature to obtain the calcium lignin sulfonate solution.

[0055] 5) adding the green body material into a mold, pouring and vibrating the green body into a mold, curing the green body at 25-30° C. for 4-6 hours, and then demolding the green body, and drying the green body at 100-120° C. for 3-5 hours to obtain a green body in a sagger;

[0056] 6) The sagger green body is placed at 1380° C. and kept warm for 6 hours, and then cooled to room temperature along with the furnace to obtain a lithium absorption-proof sagger for sintering a lithium cobalt oxide positive electrode.

[0057] The amorphous aluminum oxide is in an amorphous state, has a particle size of 6 to 8 μm, and has an Al2O3 content of ≥99.5 wt%.

[0058] The particle size of calcium hexaaluminate particles is 0.1-6 mm, wherein the mass ratio of [0.1-0.5 mm] particles: [1-2 mm] particles: [3-4 mm] particles: [5-6 mm] particles is 3:25:25:6.

[0059] The particle size of the fused magnesia fine powder is 35-45 μm, and the MgO content is ≥99wt%.

[0060] The brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2ZLA, refer to GB / T31968-2015.

[0061] Figure 1 This is a photo of the appearance of the anti-lithium absorption sagger for sintering lithium cobalt oxide positive electrodes prepared in Example 1 during the erosion test. It can be seen that after erosion (the erosion medium is a powder uniformly mixed with lithium carbonate and cobalt tetroxide in a molar ratio of 1:1), there is no adhesion on the inner wall of the crucible, and the sample does not crack or fall off. In particular, after erosion, a uniform blue slag line is formed, indicating that the erosion medium is difficult to be absorbed by the sagger body, and the sagger sample exhibits good anti-lithium absorption properties.

[0062] Figure 2 This is an SEM image of the anti-lithium absorption sagger erosion test for lithium cobalt oxide positive electrode sintering prepared in Example 1; it can be seen that the sagger sample after corrosion showed good structural integrity, no cracking or shedding, no through holes, the particles were firmly bonded to the matrix and the grain boundaries were clear, indicating that the sagger has excellent corrosion resistance.

[0063] Figure 3 for Figure 2 From the local enlarged view, we can see that the yttrium zirconium component forms a good directional growth and array structure due to solid solution during the sintering process, which effectively resists the penetration of the lithium cobalt component and inhibits the absorption of the lithium cobalt component by the sagger sample.

[0064] The anti-lithium absorption sagger for sintering the lithium cobalt oxide positive electrode prepared by the present invention is tested:

[0065] (GB / T 2997-2015) Bulk density: 2.75g / cm 3 ;

[0066] (GB / T 2997-2015) apparent porosity: 14.9%;

[0067] (GB / T 2072-2008) compressive strength: 82MPa;

[0068] (GB / T 30873-2014) 1100℃ thermal shock test: air rapid cooling method, 48 cycles;

[0069] (GB / T14983-2008) 1100℃×30h alkaline resistance test strength change rate is 2.3%.

[0070] Example 2

[0071] 1. A lithium cobalt oxide positive electrode sintering anti-lithium absorption sagger and its preparation method, the specific steps are as follows:

[0072] 1) Potassium fluorozirconate solution: amorphous alumina were prepared in a mass ratio of 15:100, added to a roller mixer and mixed for 15-20 minutes to obtain a premix;

[0073] The concentration of potassium fluozirconate solution is 2 mol / L.

[0074] 2) keeping the premix at 700° C. for 3 hours, cooling with the furnace, and grinding to a particle size of ≤80 μm to obtain a pre-sintered material;

[0075] 3) adding calcium hexaaluminate particles: pre-calcined material: fused magnesia fine powder: rare earth composite yttrium zirconium ceramic powder: calcium dialuminate fine powder in a mass ratio of 100:80:12:9:28, adding the mixture to a blender and mixing for 15-25 minutes to obtain a mixture;

[0076] 4) adding a calcium lignin sulfonate solution accounting for 5.8 wt% of the mixture to the mixture, stirring for 8 to 10 minutes to obtain a green body;

[0077] The preparation process of the calcium lignin sulfonate solution is as follows: adding calcium lignin sulfonate to water at a mass ratio of 5:100 into a container, stirring at 85-90° C., and cooling to room temperature to obtain the calcium lignin sulfonate solution.

[0078] 5) adding the green body material into a mold, pouring and vibrating the green body into a mold, curing the green body at 25-30° C. for 4-6 hours, and then demolding the green body, and drying the green body at 100-120° C. for 3-5 hours to obtain a green body in a sagger;

[0079] 6) The sagger green body is placed at 1410° C. and kept warm for 4 hours, and then cooled to room temperature along with the furnace to obtain a lithium absorption-proof sagger for sintering a lithium cobalt oxide positive electrode.

[0080] The amorphous aluminum oxide is in an amorphous state, has a particle size of 6 to 8 μm, and has an Al2O3 content of ≥99.5 wt%.

[0081] The particle size of calcium hexaaluminate particles is 0.1-6 mm, wherein the mass ratio of [0.1-0.5 mm] particles: [1-2 mm] particles: [3-4 mm] particles: [5-6 mm] particles is 5:30:35:8.

[0082] The particle size of the fused magnesia fine powder is 35-45 μm, and the MgO content is ≥99wt%.

[0083] The brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2ZLA, refer to GB / T31968-2015.

[0084] The anti-lithium absorption sagger for sintering the lithium cobalt oxide positive electrode prepared by the present invention is tested:

[0085] (GB / T 2997-2015) Bulk density: 2.62g / cm 3 ;

[0086] (GB / T 2997-2015) apparent porosity: 15.2%;

[0087] (GB / T 2072-2008) compressive strength: 75MPa;

[0088] (GB / T 30873-2014) 1100℃ thermal shock test: air rapid cooling method, 54 cycles;

[0089] (GB / T14983-2008) 1100℃×30h alkaline resistance test strength change rate is 2.4%.

[0090] Example 3

[0091] 1. A lithium cobalt oxide positive electrode sintering anti-lithium absorption sagger and its preparation method, the specific steps are as follows:

[0092] 1) adding potassium fluorozirconate solution to amorphous alumina in a mass ratio of 13:100 and mixing in a roller mixer for 15-20 minutes to obtain a premix;

[0093] The concentration of the potassium fluozirconate solution is 4 mol / L.

[0094] 2) keeping the premix at 740° C. for 3 hours, cooling with the furnace, and grinding to a particle size of ≤80 μm to obtain a pre-sintered material;

[0095] 3) adding calcium hexaaluminate particles: pre-calcined material: fused magnesia fine powder: rare earth composite yttrium zirconium ceramic powder: calcium dialuminate fine powder in a mass ratio of 100:83:11:8:24, adding the mixture to a blender and mixing for 15-25 minutes to obtain a mixture;

[0096] 4) adding 6.2 wt% of calcium lignin sulfonate solution to the mixture and stirring for 8 to 10 minutes to obtain a green body;

[0097] The preparation process of the calcium lignin sulfonate solution is as follows: adding calcium lignin sulfonate to water at a mass ratio of 3:100 into a container, stirring at 85-90° C., and cooling to room temperature to obtain the calcium lignin sulfonate solution.

[0098] 5) adding the green body material into a mold, pouring and vibrating the green body into a mold, curing the green body at 25-30° C. for 4-6 hours, and then demolding the green body, and drying the green body at 100-120° C. for 3-5 hours to obtain a green body in a sagger;

[0099] 6) The sagger green body is placed at 1395° C. and kept warm for 5 hours, and then cooled to room temperature along with the furnace to obtain a lithium absorption-proof sagger for sintering a lithium cobalt oxide positive electrode.

[0100] The amorphous aluminum oxide is in an amorphous state, has a particle size of 6 to 8 μm, and has an Al2O3 content of ≥99.5 wt%.

[0101] The particle size of calcium hexaaluminate particles is 0.1-6 mm, wherein the mass ratio of [0.1-0.5 mm] particles: [1-2 mm] particles: [3-4 mm] particles: [5-6 mm] particles is 4:27:32:7.

[0102] The particle size of the fused magnesia fine powder is 35-45 μm, and the MgO content is ≥99wt%.

[0103] The brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2ZLA, refer to GB / T31968-2015.

[0104] The anti-lithium absorption sagger for sintering the lithium cobalt oxide positive electrode prepared by the present invention is tested:

[0105] (GB / T 2997-2015) Bulk density: 2.78g / cm 3 ;

[0106] (GB / T 2997-2015) apparent porosity: 14.6%;

[0107] (GB / T 2072-2008) compressive strength: 80MPa;

[0108] (GB / T 30873-2014) 1100℃ thermal shock test: air rapid cooling method, 45 cycles;

[0109] (GB / T14983-2008) 1100℃×30h alkaline resistance test strength change rate is 2.1%.

[0110] Comparative Example 1

[0111] 1. A sagger for sintering a lithium cobalt oxide positive electrode and a preparation method thereof, the specific steps are as follows:

[0112] 1) Potassium fluorozirconate solution and amorphous alumina were prepared in a mass ratio of 5:100 and added to a roller mixer and mixed for 15 to 20 minutes to obtain a premix;

[0113] The concentration of potassium fluozirconate solution is 2 mol / L.

[0114] 2) keeping the premix at 700° C. for 3 hours, cooling with the furnace, and grinding to a particle size of ≤80 μm to obtain a pre-sintered material;

[0115] 3) adding calcium hexaaluminate particles: pre-calcined material: fused magnesia fine powder: rare earth composite yttrium zirconium ceramic powder: calcium dialuminate fine powder in a mass ratio of 100:10:12:9:28, adding the mixture to a blender and mixing for 15-25 minutes to obtain a mixture;

[0116] 4) adding a calcium lignin sulfonate solution accounting for 5.8 wt% of the mixture to the mixture, stirring for 8 to 10 minutes to obtain a green body;

[0117] The preparation process of the calcium lignin sulfonate solution is as follows: adding calcium lignin sulfonate to water at a mass ratio of 5:100 into a container, stirring at 85-90° C., and cooling to room temperature to obtain the calcium lignin sulfonate solution.

[0118] 5) adding the green body material into a mold, pouring and vibrating the green body into a mold, curing the green body at 25-30° C. for 4-6 hours, and then demolding the green body, and drying the green body at 100-120° C. for 3-5 hours to obtain a green body in a sagger;

[0119] 6) The sagger green body is placed at 1450° C. and kept warm for 4 hours, and then cooled to room temperature along with the furnace to obtain a lithium absorption-proof sagger for sintering a lithium cobalt oxide positive electrode.

[0120] The amorphous aluminum oxide is in an amorphous state, has a particle size of 6 to 8 μm, and has an Al2O3 content of ≥99.5 wt%.

[0121] The particle size of the calcium hexaaluminate particles is 0.1 to 6 mm, wherein the mass ratio of [0.1 to 0.5 mm] particles: [1 to 2 mm] particles: [3 to 4 mm] particles: [5 to 6 mm] particles is 30:30:30:30.

[0122] The particle size of the fused magnesia fine powder is 35-45 μm, and the MgO content is ≥99wt%.

[0123] The brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2ZLA, refer to GB / T31968-2015.

[0124] The anti-lithium absorption sagger for sintering the lithium cobalt oxide positive electrode prepared by the present invention is tested:

[0125] (GB / T 2997-2015) Bulk density: 2.89 g / cm 3 ;

[0126] (GB / T 2997-2015) apparent porosity: 19.4%;

[0127] (GB / T 2072-2008) compressive strength: 43MPa;

[0128] (GB / T 30873-2014) 1100℃ thermal shock test: air rapid cooling method, 26 cycles;

[0129] (GB / T14983-2008) 1100℃×30h alkaline resistance test strength change rate is 7.6%.

[0130] Compared with Example 2, it can be seen that reducing the content of potassium fluorozirconate in the premix and reducing the amount of pre-burned material added, although the sintering temperature of the sagger sample is increased, the change in the content of potassium zirconium component leads to a decrease in the basicity of the sample and inhibition of the solid solution process, which weakens the thermodynamic stability of the material system and significantly reduces the sintering and service performance of the sagger sample.

[0131] Any matters not mentioned above shall be subject to the existing technology.

[0132] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a lithium-absorbing anti-sag sagger for sintering a lithium cobalt oxide positive electrode, characterized in that: The specific steps are as follows: S1. The potassium fluorozirconate solution and amorphous alumina are mixed to obtain a premix; S2. The premix is heat treated and ground to obtain a pre-burned material after cooling in the furnace; S3. The six calcium aluminate particles, pre-sintered material, fused magnesia powder, rare earth composite yttrium zirconium ceramic powder and calcium dialuminate powder mixed to obtain a mixture; S4. Calcium lignin sulfonate solution was added to the mixture and stirred to obtain a green body material; S5. The green body material is poured into vibration molding, curing, demoulding, and drying to obtain a green body in a sagger; S6. After the green body of the sagger is heat treated, the furnace is cooled to room temperature to obtain a lithium cobalt oxide positive electrode sintered with anti-lithium absorption sagger; The concentration of the potassium fluorozirconate solution is 2-4 mol / L; the mass ratio of the potassium fluorozirconate solution to the amorphous aluminum oxide is (12-15):100; The mass ratio of the calcium hexaaluminate particles: the pre-sintered material: the fused magnesia fine powder: the rare earth composite yttrium zirconium ceramic powder: the calcium dialuminate fine powder is 100: (80-85): (10-12): (6-9): (20-28); The amorphous aluminum oxide is in a non-crystalline state.

2. The method for preparing a lithium-absorbing-proof sagger for sintering a lithium cobalt oxide positive electrode according to claim 1, wherein: In step S2, the heat treatment is carried out at 700-800°C for 2-3 hours.

3. The method for preparing a lithium-absorbing-proof sagger for sintering a lithium cobalt oxide positive electrode according to claim 1, wherein: The particle size of the pre-burned material is ≤80 μm.

4. The method for preparing a lithium-absorbing-proof sagger for sintering a lithium cobalt oxide positive electrode according to claim 1, wherein: The calcium lignin sulfonate solution is prepared by stirring and mixing calcium lignin sulfonate and water in a mass ratio of (1-5):100 at 85-90° C.; and / or, the calcium lignin sulfonate solution accounts for 5.8-6.6 wt % of the mixture.

5. The method for preparing a lithium-absorbing-proof sagger for sintering a lithium cobalt oxide positive electrode according to claim 1, wherein: In step S5, the green body material is added into a mold, poured and vibrated into shape, cured at 25-30° C. for 4-6 hours, demolded, and dried at 100-120° C. for 3-5 hours to obtain a sagger green body.

6. The method for preparing a lithium-absorbing-proof sagger for sintering a lithium cobalt oxide positive electrode according to claim 1, wherein: In step S6, the heat treatment is to place the sagger green body at 1380-1410° C. and keep it warm for 4-6 hours.

7. The method for preparing a lithium-absorbing-proof sagger for sintering a lithium cobalt oxide positive electrode according to claim 1, wherein: Amorphous alumina with a particle size of 6-8 μm and an Al2O3 content of ≥99.5wt%; and\or, The particle size of the calcium hexaaluminate particles is 0.1-6 mm, wherein the mass ratio of [0.1-0.5 mm] particles: [1-2 mm] particles: [3-4 mm] particles: [5-6 mm] particles is (3-5): (25-30): (25-35): (6-8); and\or, The fused magnesia fine powder has a particle size of 35-45 μm and a MgO content of ≥99 wt%; and\or, The grade of the rare earth composite yttrium zirconium ceramic powder is YZ7.2ZLA, with reference to GB / T31968-2015.

8. A lithium absorption-proof sagger for sintering lithium cobalt oxide positive electrodes prepared by the preparation method according to any one of claims 1 to 7.

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