A double-layer composite reactor for sintering lithium battery positive electrode material and a preparation method thereof

Abstract

The application discloses a kind of lithium battery positive electrode material sintering with double-layer composite reactor and preparation method thereof, belong to the technical field of reactor kiln furniture preparation, reactor includes matrix layer and facing layer, the mass percentage of each raw material of matrix layer includes: cordierite 20~30%, talcum powder 0~10%, mullite 20~22%, tabular corundum 18~20%, active alumina 12~18%, lithium feldspar 6~8%, guangxi white mud 4~8%;Add binder to the total mass percentage of the matrix layer 4~8%;The mass percentage of each raw material of facing layer includes: high-purity SiC-Si3N4 35~45%, zirconium mullite 15~20%, lithium feldspar 15~20%, active alumina 12~18%, guangxi white mud 4~8%;Add binder to the total mass percentage of the facing layer 4~8%.The above-mentioned double-layer composite reactor provided in the application can maintain stable structure and performance under high temperature environment, effectively resist the corrosive substances released in high-temperature sintering process, avoid the reactor surface skin, drop slag, ensure the purity and performance of positive electrode material.

Description

Technical Field

[0001] This invention relates to the field of reactor kiln furniture preparation technology, and more specifically, to a double-layer composite reactor for sintering lithium battery cathode materials and its preparation method. Background Technology

[0002] With the widespread application of lithium-ion batteries in 3C electronic products, power batteries, and energy storage, the production scale of lithium battery cathode materials is continuously expanding, leading to an increasing demand for sintering reactors. In the sintering process of ternary lithium battery cathode materials, the reactor, as a crucial load-bearing and protective device, directly affects the quality and production efficiency of the cathode material due to its corrosion resistance and service life. Currently, the most widely used reactor material on the market is cordierite-mullite composite material, which uses the composite structure of cordierite and mullite to improve the reactor's heat resistance and mechanical strength.

[0003] However, during the high-temperature sintering process of ternary lithium battery cathode materials, the cathode materials release highly corrosive substances such as Li₂O and CoO. These substances react chemically with the reactor materials to generate products such as LiAlO₂ and LiAlSiO₄. Because the thermal expansion coefficients of these products do not match the reactor matrix material, significant thermal stress is generated inside the reactor, leading to cracks and structural damage. For example, Zhang Lifen et al. reported on this in their paper "LiNi x Co y Mn 1-x-y The article "The Erosion Process of Reactor by O2 Cathode Material Synthesis" points out that the LiAlO2 generated by the reaction of cordierite-mullite reactor with Li2O at high temperature will cause the reactor surface to peel and slag, which will seriously affect the purity of the cathode material.

[0004] Existing reactors are prone to structural damage during high-temperature sintering, resulting in a short service life. The average service life of existing cordierite-mullite reactors is only 20-30 cycles, far from meeting the demands of large-scale production. Frequent reactor replacements not only increase production costs but also disrupt the continuous operation of the production line. Furthermore, during high-temperature sintering and cooling, the mismatch in thermal expansion coefficients easily leads to thermal stress concentration, causing cracks and ruptures after multiple thermal cycles, resulting in poor thermal shock resistance. To address these issues, researchers have attempted to improve the reactor's erosion resistance and thermal shock resistance by adding materials such as silicon carbide and zirconium mullite. However, these improvement schemes still suffer from high costs and complex preparation processes.

[0005] Therefore, developing a reactor for sintering lithium battery cathode materials with high erosion resistance, excellent thermal shock resistance, and long service life has become an urgent need in the field of lithium battery cathode material production. Summary of the Invention

[0006] To address the shortcomings and deficiencies of existing technologies, this invention provides a double-layer composite reactor for sintering lithium battery cathode materials and its preparation method. This reactor effectively resists the erosion of lithium battery cathode materials by the release of corrosive substances during high-temperature sintering, preventing surface peeling and flaking. It can be repeatedly recycled at high temperatures, exhibits excellent thermal shock resistance, and ensures the purity and performance of the cathode material. The technical solution is as follows:

[0007] A bilayer composite reactor for sintering lithium battery cathode materials includes a matrix layer and a face layer. The matrix layer comprises the following raw materials by mass percentage: cordierite 20%~30%, talc powder 0~10%, mullite 20%~22%, tabular corundum 18%~20%, activated alumina 12%~18%, lithium feldspar 6%~8%, and Guangxi white clay 4%~8%; a binder comprising 4%~8% of the total mass percentage of the matrix layer is added. The face layer comprises the following raw materials by mass percentage: high-purity SiC-Si3N4 35%~45%, zirconium mullite 15%~20%, lithium feldspar 15%~20%, activated alumina 12%~18%, and Guangxi white clay 4%~8%; a binder comprising 4%~8% of the total mass percentage of the face layer is added.

[0008] This application employs a dual-layer structure design consisting of a matrix layer and a surface layer. The matrix layer provides strength and thermal shock resistance, while the surface layer provides corrosion resistance and surface density. Specifically, the matrix layer incorporates aggregates such as cordierite, mullite, and tabular corundum to form a dense network structure, enhancing the reactor's mechanical strength and thermal shock stability. The surface layer adds high-purity SiC-Si3N4, zirconium mullite, and lithium feldspar, significantly improving corrosion resistance, preventing the cathode material from eroding the reactor, avoiding peeling and flaking, and ensuring the purity of the cathode material. In summary, the matrix layer and surface layer work synergistically to improve the overall structural consistency and stability of the reactor, ensuring superior mechanical and thermal shock performance at high temperatures, reducing the risk of thermal stress concentration, and extending the reactor's service life.

[0009] Furthermore, the mass percentage of each raw material in the matrix layer includes: cordierite 24%~26%, talc powder 4%~6%, mullite 20%~22%, tabular corundum 18%~20%, activated alumina 14%~16%, lithium feldspar 6%~8%, and Guangxi white clay 5%~6%.

[0010] Furthermore, the particle size of the matrix layer raw materials cordierite and mullite is 1mm~3mm, and the particle size of the raw materials talc, tabular corundum, activated alumina, Guangxi white clay and lithium feldspar is 0.04mm~0.08mm.

[0011] Furthermore, the mass percentage of each raw material in the fabric layer includes: 38%~44% high-purity SiC-Si3N4, 16%~18% zircon-mullite, 16%~18% lithium feldspar, 14%~16% activated alumina, and 5%~6% Guangxi white clay.

[0012] Furthermore, the particle size of each raw material in the fabric layer is 0.04mm to 0.08mm.

[0013] Furthermore, based on the total mass percentage of high-purity SiC-Si3N4, the SiC content is 65%~85%.

[0014] By precisely controlling the particle size, the coarse aggregate in the matrix layer acts as a skeleton within the reactor matrix, while fine particles fill the gaps in the skeleton, increasing density and bonding strength. This results in a denser network structure that effectively disperses thermal stress and reduces crack formation. When the reactor experiences sudden temperature changes, the aggregates support each other, reducing crack initiation and propagation, making the reactor more stable under thermal shock conditions, lowering the risk of breakage, and extending its service life. This provides strong protection for the reactor's application under complex conditions. The surface layer uses materials with small particle sizes, improving the reactor surface density and fineness. The synergistic effect of the matrix and surface layers enhances the overall strength and service life of the reactor, while also addressing material waste. The addition of silicon carbide and lithium feldspar improves the reactor's corrosion resistance.

[0015] By controlling the SiC content in high-purity SiC-Si3N4 within the aforementioned range, it is possible to balance wear resistance, thermal conductivity, and erosion resistance, thereby optimizing the high-temperature performance of the reactor.

[0016] Furthermore, the binder in the matrix layer includes an aluminum dihydrogen phosphate solution with a concentration of 60 wt%.

[0017] Furthermore, the binder in the fabric layer includes an aluminum dihydrogen phosphate solution with a concentration of 60 wt%.

[0018] This application further uses a 60wt% aluminum dihydrogen phosphate solution as a binder to improve the bonding strength between the matrix layer and the fabric layer, prevent delamination and peeling, and ensure the overall molding performance of the reactor; moreover, the binder forms a ceramic bonding phase at high temperature, which enhances the overall structural stability and adapts to multiple thermal cycles.

[0019] Furthermore, the thickness of the substrate layer is 10mm~15mm to ensure the overall strength of the reactor.

[0020] Furthermore, the thickness of the fabric layer is 2mm~3mm, which improves the protection effect of the inner wall of the reactor.

[0021] Furthermore, the fabric layer is located on the bottom inner wall and bottom side wall of the double-layer composite reactor, precisely protecting the most vulnerable parts of the reactor, reducing costs, and avoiding excessive material waste.

[0022] Secondly, this application also provides a method for preparing a bilayer composite reactor, comprising the following steps:

[0023] S1. Weigh out the cordierite particles and mullite particles of the matrix layer raw materials according to the proportion, put them into the mixer and mix for 20 min to 30 min. After mixing, add water and binder and mix again for 10 min to 15 min to obtain wet granules.

[0024] S2. Weigh out the matrix layer raw materials talc powder, tabular corundum, activated alumina, lithium feldspar and Guangxi white clay according to the proportion, add them together with the wet granules obtained in S1 into the mixer and mix for 20 min to 30 min to obtain the matrix layer mixture.

[0025] S3. Weigh out the raw materials for the fabric layer, including high-purity SiC-Si3N4, zircon mullite, lithium feldspar, activated alumina, and Guangxi white clay, according to the proportion. Put them into a mixer and mix for 10-20 minutes. After mixing, add water and binder and mix again for 10-15 minutes to obtain the wet powder of the fabric layer.

[0026] S4. The matrix layer mixture and the wet powder of the face layer, which are evenly mixed in S2 and S3, are aged at room temperature and placed in a cool and dry place for 24h~48h. After aging, the matrix layer green material and the face layer green material are obtained.

[0027] S5. The prepared fabric layer green blank is laid flat on the inner wall of the bottom of the reactor corresponding to the position of the mold, and then the prepared matrix layer green blank is loaded into the mold. After pressing, drying, firing and cooling, the double-layer composite reactor is obtained.

[0028] Furthermore, in step S1, based on the total mass of the cordierite and the mullite, the mass percentage of the binder and the water is 5%, and the ratio of the binder to the water is 4:1. This control of the binder-to-water ratio further optimizes wettability and formability, ensuring good bonding between particles; controlling the total amount of binder and water to 5% avoids excessive liquid phase leading to uneven shrinkage or cracking.

[0029] Furthermore, the pressing molding process includes pressing a mold containing the base layer green blank and the fabric layer green blank using a hydraulic press for 10s to 15s to obtain a blank.

[0030] Furthermore, the drying process includes feeding the pressed blank into a drying chamber with an initial temperature of 30°C to 50°C, drying for 2 to 3 hours, slowly raising the temperature to 80 to 100°C, and then drying for another 4 to 6 hours until the moisture content is 0.5% to 0.8%. The drying process is controlled by segmented temperature increases to prevent cracking caused by excessively rapid moisture evaporation.

[0031] Furthermore, the firing and cooling process involves placing the dried green body into a high-temperature kiln and firing it at 1350℃~1400℃ for 12h~16h at a rate of ≤5℃ / min, followed by cooling to room temperature to obtain the reactor. Controlling the heating rate within the above range avoids excessively rapid heating that could cause thermal shock and lead to reactor cracking.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) This invention provides a double-layer composite reactor. Cordierite and mullite aggregate particles are added to the matrix layer to form a dense network structure, which can effectively disperse thermal stress and improve the matrix strength and thermal shock resistance of the reactor. The surface layer is made of materials with small particle size and contains high-purity SiC-Si3N4, lithium feldspar and other materials to improve the surface density and fineness of the reactor, further improving the reactor's resistance to erosion and high temperature resistance. It can maintain a stable structure and performance in a high temperature environment of 1350~1400℃, effectively resisting the corrosive substances released by the lithium battery cathode material during high temperature sintering, avoiding peeling and slagging on the reactor surface, and ensuring the purity and performance of the cathode material.

[0034] (2) By precisely controlling the raw material ratio and particle size of the substrate layer and the fabric layer, this invention ensures that the reactor has good thermal shock performance during high-temperature sintering and cooling, avoids cracks and ruptures, significantly improves the service life of the reactor, and increases the number of times it can be reused to more than 50 times, thereby reducing production costs. Moreover, the preparation process is simple and inexpensive, making it suitable for the sintering process of various lithium battery cathode materials and reducing material waste. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0036] This embodiment incorporates cordierite and mullite aggregate particles into the matrix layer to form a dense network structure, effectively dispersing thermal stress and improving the reactor's matrix strength and thermal shock resistance. The surface layer uses materials with small particle sizes and includes high-purity SiC-Si3N4 and lithium feldspar, increasing the reactor's surface density and fineness. This further enhances the reactor's erosion resistance and high-temperature performance, allowing it to maintain stable structure and performance even at high temperatures of 1350-1400℃. This effectively resists corrosive substances released during the high-temperature sintering of lithium battery cathode materials, preventing surface peeling and flaking, and ensuring the purity and performance of the cathode material. Specific implementation details are as follows:

[0037] A bilayer composite reactor for sintering lithium battery cathode materials includes a matrix layer and a face layer. The matrix layer comprises the following raw materials by mass percentage: cordierite 20%~30%, talc powder 0~10%, mullite 20%~22%, tabular corundum 18%~20%, activated alumina 12%~18%, lithium feldspar 6%~8%, and Guangxi white clay 4%~8%; a binder comprising 4%~8% of the total mass percentage of the matrix layer is added. The face layer comprises the following raw materials by mass percentage: high-purity SiC-Si3N4 35%~45%, zirconium mullite 15%~20%, lithium feldspar 15%~20%, activated alumina 12%~18%, and Guangxi white clay 4%~8%; a binder comprising 4%~8% of the total mass percentage of the face layer is added.

[0038] This application employs a dual-layer structure design consisting of a matrix layer and a surface layer. The matrix layer provides strength and thermal shock resistance, while the surface layer provides corrosion resistance and surface density. Specifically, the matrix layer incorporates aggregates such as cordierite, mullite, and tabular corundum to form a dense network structure, enhancing the reactor's mechanical strength and thermal shock stability. The surface layer adds high-purity SiC-Si3N4, zirconium mullite, and lithium feldspar, significantly improving corrosion resistance, preventing the cathode material from eroding the reactor, avoiding peeling and flaking, and ensuring the purity of the cathode material. In summary, the matrix layer and surface layer work synergistically to improve the overall structural consistency and stability of the reactor, ensuring superior mechanical and thermal shock performance at high temperatures, reducing the risk of thermal stress concentration, and extending the reactor's service life.

[0039] In a preferred embodiment, the mass percentage of each raw material in the matrix layer includes: cordierite 24%~26%, talc powder 4%~6%, mullite 20%~22%, tabular corundum 18%~20%, activated alumina 14%~16%, lithium feldspar 6%~8%, and Guangxi white clay 5%~6%.

[0040] In a preferred embodiment, the particle size of the matrix layer raw materials cordierite and mullite is 1mm to 3mm, and the particle size of the raw materials talc, tabular corundum, activated alumina, Guangxi white clay, and lithium feldspar is 0.04mm to 0.08mm.

[0041] In a preferred embodiment, the mass percentage of each raw material in the fabric layer includes: 38%~44% high-purity SiC-Si3N4, 16%~18% zircon-mullite, 16%~18% lithium feldspar, 14%~16% activated alumina, and 5%~6% Guangxi white clay.

[0042] In a preferred embodiment, the particle size of each raw material in the fabric layer is 0.04mm to 0.08mm.

[0043] As a preferred embodiment, the SiC content is 65% to 85% based on the total mass percentage of high-purity SiC-Si3N4.

[0044] By precisely controlling the particle size, the coarse aggregate in the matrix layer acts as a skeleton within the reactor matrix, while fine particles fill the gaps in the skeleton, increasing density and bonding strength. This results in a denser network structure that effectively disperses thermal stress and reduces crack formation. When the reactor experiences sudden temperature changes, the aggregates support each other, reducing crack initiation and propagation, making the reactor more stable under thermal shock conditions, lowering the risk of breakage, and extending its service life. This provides strong protection for the reactor's application under complex conditions. The surface layer uses materials with small particle sizes, improving the reactor surface density and fineness. The synergistic effect of the matrix and surface layers enhances the overall strength and service life of the reactor, while also addressing material waste. The addition of silicon carbide and lithium feldspar improves the reactor's corrosion resistance.

[0045] By controlling the SiC content in high-purity SiC-Si3N4 within the aforementioned range, it is possible to balance wear resistance, thermal conductivity, and erosion resistance, thereby optimizing the high-temperature performance of the reactor.

[0046] In a preferred embodiment, the binder in the matrix layer comprises an aluminum dihydrogen phosphate solution with a concentration of 60 wt%.

[0047] In a preferred embodiment, the binder in the fabric layer comprises an aluminum dihydrogen phosphate solution with a concentration of 60 wt%.

[0048] This application further uses a 60wt% aluminum dihydrogen phosphate solution as a binder to improve the bonding strength between the matrix layer and the fabric layer, prevent delamination and peeling, and ensure the overall molding performance of the reactor; moreover, the binder forms a ceramic bonding phase at high temperature, which enhances the overall structural stability and adapts to multiple thermal cycles.

[0049] In a preferred embodiment, the thickness of the substrate layer is 10mm to 15mm to ensure the overall strength of the reactor.

[0050] In a preferred embodiment, the thickness of the fabric layer is 2mm to 3mm, which improves the protection effect of the inner wall of the reactor.

[0051] In a preferred embodiment, the fabric layer is located on the bottom inner wall and bottom side wall of the double-layer composite reactor, which precisely protects the most vulnerable parts of the reactor, reduces costs, and avoids excessive material waste.

[0052] Secondly, this application also provides a method for preparing a bilayer composite reactor, comprising the following steps:

[0053] S1. Weigh out the cordierite particles and mullite particles of the matrix layer raw materials according to the proportion, put them into the mixer and mix for 20 min to 30 min. After mixing, add water and binder and mix again for 10 min to 15 min to obtain wet granules.

[0054] S2. Weigh out the matrix layer raw materials talc powder, tabular corundum, activated alumina, lithium feldspar and Guangxi white clay according to the proportion, add them together with the wet granules obtained in S1 into the mixer and mix for 20 min to 30 min to obtain the matrix layer mixture.

[0055] S3. Weigh out the raw materials for the fabric layer, including high-purity SiC-Si3N4, zircon mullite, lithium feldspar, activated alumina, and Guangxi white clay, according to the proportion. Put them into a mixer and mix for 10-20 minutes. After mixing, add water and binder and mix again for 10-15 minutes to obtain the wet powder of the fabric layer.

[0056] S4. The matrix layer mixture and the wet powder of the face layer, which are evenly mixed in S2 and S3, are aged at room temperature and placed in a cool and dry place for 24h~48h. After aging, the matrix layer green material and the face layer green material are obtained.

[0057] S5. The prepared fabric layer green blank is laid flat on the inner wall of the bottom of the reactor corresponding to the position of the mold, and then the prepared matrix layer green blank is loaded into the mold. After pressing, drying, firing and cooling, the double-layer composite reactor is obtained.

[0058] In a preferred embodiment, in step S1, based on the total mass of the cordierite and the mullite, the mass percentage of the binder and the water is 5%, and the ratio of the binder to the water is 4:1. This control of the binder-to-water ratio further optimizes wettability and formability, ensuring good bonding between particles; controlling the total amount of binder and water to 5% avoids excessive liquid phase leading to uneven shrinkage or cracking.

[0059] In a preferred embodiment, the pressing process includes pressing a mold containing the base layer green blank and the fabric layer green blank using a hydraulic press for 10s to 15s to obtain a blank.

[0060] In a preferred embodiment, the drying process includes placing the pressed blank into a drying chamber with an initial temperature of 30°C to 50°C, drying for 2 to 3 hours, gradually increasing the temperature to 80 to 100°C, and then drying for another 4 to 6 hours until the moisture content is 0.5% to 0.8%. The drying process is controlled by segmented temperature increases to prevent excessively rapid moisture evaporation that could lead to cracking.

[0061] In a preferred embodiment, the firing and cooling process involves placing the dried green body into a high-temperature kiln and firing it at 1350℃~1400℃ for 12h~16h at a rate of ≤5℃ / min, followed by cooling to room temperature to obtain the reactor. Controlling the heating rate within the above range avoids excessively rapid heating that could cause thermal shock and lead to reactor cracking.

[0062] The following examples further illustrate the beneficial effects of the bilayer composite reactor for sintering lithium battery cathode materials and its preparation method provided by the present invention.

[0063] Example 1:

[0064] This embodiment 1 provides a bilayer composite reactor for sintering lithium battery cathode materials, comprising a matrix layer and a surface layer. The matrix layer comprises the following raw materials by mass percentage: cordierite 20%, talc 10%, mullite 20%, tabular corundum 20%, activated alumina 14%, lithium feldspar 8%, and Guangxi white clay 8%. Aluminum dihydrogen phosphate solution comprising 4% of the total mass percentage of the matrix layer is then added. The cordierite and mullite have a particle size of 1-3 mm, while the talc, tabular corundum, activated alumina, Guangxi white clay, and lithium feldspar have a particle size of 0.04-0.08 mm. The surface layer comprises the following raw materials by mass percentage: high-purity SiC-Si3N4 35%, zircon-mullite 20%, lithium feldspar 20%, activated alumina 17%, and Guangxi white clay 8%. Aluminum dihydrogen phosphate solution comprising 4% of the total mass percentage of the matrix layer is then added. All raw materials have a particle size of 0.04-0.08 mm. The thickness of the substrate layer is 10 mm, and the thickness of the fabric layer is 2 mm. The preparation method of the above-mentioned double-layer composite reactor includes the following steps:

[0065] S1. Weigh out the matrix layer raw materials cordierite and mullite according to the proportion, put them into the mixer and mix for 30 minutes. After mixing, add water and binder and mix twice for 15 minutes each time to obtain wet granules. The mass percentage of binder to water is 5%, and the mixing ratio of binder to water is 4:1.

[0066] S2. Weigh out the matrix layer raw materials talc powder, tabular corundum, activated alumina, lithium feldspar and Guangxi white clay according to the proportion, add them together with the wet granules obtained in S1 into the mixer and mix for 30 minutes to obtain the matrix layer mixture.

[0067] S3. Weigh out the raw materials for the fabric layer, including high-purity SiC-Si3N4, zircon mullite, lithium feldspar, activated alumina and Guangxi white clay, according to the proportion. Put them into a mixer and mix for 20 minutes. After mixing, add water and binder and mix twice for 15 minutes each time to obtain the wet powder of the fabric layer.

[0068] S4. The matrix layer mixture and the wet powder of the face layer, which are mixed evenly in S2 and S3, are aged at room temperature and placed in a cool and dry place for 48 hours. After aging, the matrix layer green material and the face layer green material are obtained.

[0069] S5. The prepared fabric layer green blank is laid flat on the inner wall of the bottom of the reactor corresponding to the position of the mold, and then the prepared base layer green blank is loaded into the mold and pressed by a hydraulic press under a pressure of 160KPa for 15s to form the shape.

[0070] S6. The pressed reactor blank is sent into the drying chamber and dried until the moisture content is 0.8%;

[0071] S7. Place the dried green body into a high-temperature kiln and fire it at 1400℃ for 16 hours with a heating rate of ≤5℃ / min. After cooling to room temperature, the reactor is obtained.

[0072] S8. Perform quality checks on the prepared cathode material using a reactor to ensure it meets specifications and standards.

[0073] Example 2:

[0074] This embodiment 2 provides a bilayer composite reactor for sintering lithium battery cathode materials, comprising a matrix layer and a surface layer. The matrix layer comprises the following raw materials by mass percentage: cordierite 23%, talc 6%, mullite 22%, tabular corundum 20%, activated alumina 16%, lithium feldspar 7%, and Guangxi white clay 6%. An aluminum dihydrogen phosphate solution comprising 6% of the total mass of the matrix layer is then added. The cordierite and mullite have a particle size of 1-3 mm, while the talc, tabular corundum, activated alumina, Guangxi white clay, and lithium feldspar have a particle size of 0.04-0.08 mm. The surface layer comprises the following raw materials by mass percentage: high-purity SiC-Si3N4 42%, zircon-mullite 16%, lithium feldspar 18%, activated alumina 16%, and Guangxi white clay 8%. An aluminum dihydrogen phosphate solution comprising 6% of the total mass of the matrix layer is then added. All raw materials have a particle size of 0.04-0.08 mm. The thickness of the substrate layer is 13 mm, and the thickness of the fabric layer is 3 mm. The preparation method of the above-mentioned double-layer composite reactor includes the following steps:

[0075] The preparation method of the above-mentioned double-layer composite reactor includes the following steps:

[0076] S1. Weigh out the matrix layer raw materials cordierite and mullite according to the proportion, put them into the mixer and mix for 23 minutes. After mixing, add water and binder and mix twice for 13 minutes to obtain wet granules. The mass percentage of binder to water is 5%, and the mixing ratio of binder to water is 4:1.

[0077] S2. Weigh out the matrix layer raw materials talc powder, tabular corundum, activated alumina, lithium feldspar and Guangxi white clay according to the proportion, add them together with the wet granules obtained in S1 into the mixer and mix for 25 minutes to obtain the matrix layer mixture.

[0078] S3. Weigh out the raw materials for the fabric layer, including high-purity SiC-Si3N4, zircon mullite, lithium feldspar, activated alumina and Guangxi white clay, according to the proportion. Put them into a mixer and mix for 15 minutes. After mixing, add water and binder and mix twice for 13 minutes to obtain the wet powder of the fabric layer.

[0079] S4. The matrix layer mixture and the wet powder of the face layer, which are mixed evenly in S2 and S3, are aged at room temperature and placed in a cool and dry place for 36 hours. After aging, the matrix layer green material and the face layer green material are obtained.

[0080] S5. The prepared fabric layer green material is laid flat on the inner wall of the bottom of the reactor corresponding to the position of the mold, and then the prepared base layer green material is loaded into the mold and pressed by a hydraulic press under a pressure of 150KPa for 13s to form the shape.

[0081] S6. The pressed reactor blank is sent into the drying chamber and dried until the moisture content is 0.6%;

[0082] S7. Place the dried green body into a high-temperature kiln and fire it at 1350℃ for 14 hours with a heating rate of ≤5℃ / min. After cooling to room temperature, the reactor is obtained.

[0083] S8. Perform quality checks on the prepared cathode material using a reactor to ensure it meets specifications and standards.

[0084] Example 3:

[0085] This embodiment 3 provides a bilayer composite reactor for sintering lithium battery cathode materials, comprising a matrix layer and a surface layer. The matrix layer comprises the following raw materials by mass percentage: cordierite 26%, talc 4%, mullite 21%, tabular corundum 18%, activated alumina 18%, lithium feldspar 6%, and Guangxi white clay 7%. An aluminum dihydrogen phosphate solution comprising 8% of the total mass percentage of the matrix layer is added. The cordierite and mullite have a particle size of 1-3 mm, while the talc, tabular corundum, activated alumina, Guangxi white clay, and lithium feldspar have a particle size of 0.04-0.08 mm. The surface layer comprises the following raw materials by mass percentage: high-purity SiC-Si3N4 45%, zircon-mullite 18%, lithium feldspar 17%, activated alumina 14%, and Guangxi white clay 6%. An aluminum dihydrogen phosphate solution comprising 8% of the total mass percentage of the matrix layer is added. All raw materials have a particle size of 0.04-0.08 mm. The thickness of the substrate layer is 15 mm, and the thickness of the fabric layer is 3 mm. The preparation method of the above-mentioned double-layer composite reactor includes the following steps:

[0086] The preparation method of the above-mentioned double-layer composite reactor includes the following steps:

[0087] S1. Weigh out the matrix layer raw materials cordierite and mullite according to the proportion, put them into the mixer and mix for 20 minutes. After mixing, add water and binder and mix twice for 10 minutes each time to obtain wet granules. The mass percentage of binder to water is 5%, and the mixing ratio of binder to water is 4:1.

[0088] S2. Weigh out the matrix layer raw materials talc powder, tabular corundum, activated alumina, lithium feldspar and Guangxi white clay according to the proportion, add them together with the wet granules obtained in S1 into the mixer and mix for 20 minutes to obtain the matrix layer mixture.

[0089] S3. Weigh out the raw materials for the fabric layer, including high-purity SiC-Si3N4, zircon mullite, lithium feldspar, activated alumina and Guangxi white clay, according to the proportion. Put them into a mixer and mix for 10 minutes. After mixing, add water and binder and mix twice for 10 minutes each time to obtain wet powder material for the fabric layer.

[0090] S4. The matrix layer mixture and the wet powder of the face layer, which are mixed evenly in S2 and S3, are aged at room temperature and placed in a cool and dry place for 24 hours. After aging, the matrix layer green material and the face layer green material are obtained.

[0091] S5. The prepared fabric layer green blank is laid flat on the inner wall of the bottom of the reactor corresponding to the position of the mold, and then the prepared base layer green blank is loaded into the mold and pressed by a hydraulic press under a pressure of 130KPa for 10s to form the shape.

[0092] S6. The pressed reactor blank is sent into the drying chamber and dried until the moisture content is 0.5%;

[0093] S7. Place the dried green body into a high-temperature kiln and fire it at 1350℃ for 12 hours with a heating rate of ≤5℃ / min. After cooling to room temperature, the reactor is obtained.

[0094] S8. Perform quality checks on the prepared cathode material using a reactor to ensure it meets specifications and standards.

[0095] Comparative Example 1:

[0096] Comparative Example 1 provides a reactor for sintering lithium battery cathode materials. The mass percentage of each raw material includes: 25% mullite (particle size 1mm~3mm), 25% mullite (particle size 0.5mm~1mm), 16% cordierite (particle size 1mm~2mm), 14% cordierite (particle size 0.2mm~1mm), 16% tabular corundum powder (200 mesh), 4% Guangxi white clay, and 4% aluminum dihydrogen phosphate solution as binder.

[0097] The method for preparing the above-mentioned reactor includes the following steps:

[0098] S1. Weigh out 2 types of mullite and 2 types of cordierite according to the proportion, and put them into the mixer and mix for 10 minutes;

[0099] S2. Weigh the plate-shaped corundum powder and Guangxi white clay according to the proportion, add them to the S1 mixer and mix. After mixing evenly, add aluminum dihydrogen phosphate solution and an appropriate amount of water to obtain the mixture.

[0100] S3. The mixture obtained in S2 is aged at room temperature and placed in a cool, dry place for 24 hours. After aging, the green material is obtained.

[0101] S4. The prepared green material is loaded into the mold and pressed by a hydraulic press under a pressure of 130 kPa for 10 seconds to form the shape.

[0102] S5. The pressed reactor blank is sent into the drying chamber and dried until the moisture content is below 0.5%;

[0103] S6. Place the dried green body into a high-temperature kiln, heat it to 1350℃ at ≤5℃ / min, keep it at that temperature for 4 hours, and then cool it to room temperature to obtain the reactor.

[0104] Comparative Example 2:

[0105] Comparative Example 2 provides a reactor for sintering lithium battery cathode materials. The mass percentage of each raw material includes: 22% mullite (particle size 1mm~3mm), 28% mullite (particle size 0.5mm~1mm), 15% cordierite (particle size 1mm~2mm), 15% cordierite (particle size 0.2mm~1mm), 15% tabular corundum powder (200 mesh), 5% Guangxi white clay, and 4% aluminum dihydrogen phosphate solution as binder.

[0106] The method for preparing the above-mentioned reactor includes the following steps:

[0107] S1. Weigh out 2 types of mullite and 2 types of cordierite according to the proportion, and put them into the mixer and mix for 10 minutes;

[0108] S2. Weigh the plate-shaped corundum powder and Guangxi white clay according to the proportion, add them to the S1 mixer and mix. After mixing evenly, add aluminum dihydrogen phosphate solution and an appropriate amount of water to obtain the mixture.

[0109] S3. The mixture obtained in S2 is aged at room temperature and placed in a cool, dry place for 24 hours. After aging, the green material is obtained.

[0110] S4. The prepared green material is loaded into the mold and pressed by a hydraulic press under a pressure of 130 kPa for 10 seconds to form the shape.

[0111] S5. The pressed reactor blank is sent into the drying chamber and dried until the moisture content is below 0.5%;

[0112] S6. Place the dried green body into a high-temperature kiln, heat it to 1350℃ at ≤5℃ / min, keep it at that temperature for 4 hours, and then cool it to room temperature to obtain the reactor.

[0113] The following tests were conducted on the service life of the reactors used for sintering lithium battery cathode materials obtained in the above embodiments and comparative examples. These reactors were used to calcine ternary materials for 8-series lithium-ion batteries. The service life of each reactor was determined by the occurrence of reactor breakage, resulting in partial detachment and damage. The surface condition of the reactors was also observed after multiple cycles of use. The test results are shown in Table 1.

[0114] Table 1. Performance test results of the reactors prepared in the examples and comparative examples.

[0115] Group Use 10 times Use 15 times Use 20 times Example 1 (Composite layer contact surface) A small number of microcracks with a length not exceeding 5mm A certain number of small cracks with a length not exceeding 15mm Numerous cracks, the longest being 50mm Example 2 (Composite layer contact surface) A small number of microcracks with a length not exceeding 5mm A certain number of small cracks with a length not exceeding 15mm Numerous cracks, the longest being 55mm Example 3 (Composite layer contact surface) A small number of microcracks with a length not exceeding 5mm A certain number of small cracks with a length not exceeding 15mm Numerous cracks, the longest being 50mm Comparative Example 1 (Inner Wall Contact Surface) A certain number of small cracks with a length not exceeding 20mm Numerous cracks, the longest being 75mm, and some patchy flaking, affect the quality of the sintered cathode material. Numerous cracks, significant flaking, overall failure. Comparative Example 2 (Inner Wall Contact Surface) A certain number of small cracks with a length not exceeding 20mm Numerous cracks, the longest measuring 70mm, and some patchy flaking, affect the quality of the sintered cathode material. Numerous cracks, significant flaking, overall failure.

[0116] As shown in Table 1, the reactors prepared in Examples 1 to 3 of this application did not detach after 20 uses, indicating that the high-purity SiC-Si3N4 and lithium feldspar in the fabric layer effectively resisted the erosion of corrosive substances such as Li2O and CoO. However, Comparative Examples 1 to 2 detached after 15 uses, indicating that the traditional cordierite-mullite material reacts with the cathode material at high temperature to generate products such as LiAlO2 with low expansion coefficient, resulting in surface peeling and flaking.

[0117] Moreover, the slow crack development and short length of the reactors obtained in Examples 1 to 3 of this application are mainly due to the dense network structure formed by the coarse aggregate in the matrix layer, which can effectively disperse thermal stress; while the cracks in Comparative Examples 1 to 2 expand rapidly and are long, indicating that the single-layer structure has concentrated thermal stress, which easily leads to cracking. The reactors failed completely after 20 cycles and could not be used anymore.

[0118] In summary, this invention significantly improves the reactor's erosion resistance, thermal shock resistance, and service life through a double-layer composite structure design, optimized raw materials, particle size control, and process optimization. It solves the problems of easy damage and contamination of cathode materials in traditional reactors, demonstrating significant technological progress and practical value.

[0119] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A double-layer composite reactor for sintering lithium battery cathode materials, comprising a substrate layer and a surface layer, characterized in that, The matrix layer comprises the following raw materials by mass percentage: cordierite 20%~30%, talc powder 0~10%, mullite 20%~22%, tabular corundum 18%~20%, activated alumina 12%~18%, lithium feldspar 6%~8%, and Guangxi white clay 4%~8%; and a binder comprising 4%~8% of the total mass percentage of the matrix layer is added. The raw materials of the fabric layer include the following percentages by weight: 35%~45% high-purity SiC-Si3N4, 15%~20% zircon-mullite, 15%~20% lithium feldspar, 12%~18% activated alumina, and 4%~8% Guangxi white clay; and a binder is added at a percentage of 4%~8% of the total mass of the fabric layer.

2. The double-layer composite reactor according to claim 1, characterized in that, The mass percentage of each raw material in the matrix layer includes: cordierite 24%~26%, talc powder 4%~6%, mullite 20%~22%, tabular corundum 18%~20%, activated alumina 14%~16%, lithium feldspar 6%~8%, and Guangxi white clay 5%~6%.

3. The double-layer composite reactor according to claim 1 or 2, characterized in that, The particle size of the matrix layer raw materials cordierite and mullite is 1mm~3mm, and the particle size of the raw materials talc, tabular corundum, activated alumina, Guangxi white clay and lithium feldspar is 0.04mm~0.08mm.

4. The double-layer composite reactor according to claim 1, characterized in that, The mass percentage of each raw material in the fabric layer includes: 38%~44% high-purity SiC-Si3N4, 16%~18% zircon-mullite, 16%~18% lithium feldspar, 14%~16% activated alumina, and 5%~6% Guangxi white clay.

5. The double-layer composite reactor according to claim 1 or 4, characterized in that, The particle size of each raw material in the fabric layer is 0.04mm to 0.08mm; based on the total mass percentage of high-purity SiC-Si3N4, the SiC content is 65% to 85%.

6. The double-layer composite reactor according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The binder in the matrix layer includes an aluminum dihydrogen phosphate solution with a concentration of 60 wt%; (2) The binder in the fabric layer includes aluminum dihydrogen phosphate solution with a concentration of 60 wt%.

7. The double-layer composite reactor according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The thickness of the substrate layer is 10mm~15mm; (2) The thickness of the fabric layer is 2mm~3mm; (3) The fabric layer is located on the bottom inner wall and bottom side wall of the double-layer composite reactor.

8. A method for preparing a double-layer composite reactor according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Weigh out the cordierite particles and mullite particles of the matrix layer raw materials according to the proportion, put them into the mixer and mix for 20 min to 30 min. After mixing, add water and binder and mix again for 10 min to 15 min to obtain wet granules. S2. Weigh out the matrix layer raw materials talc powder, tabular corundum, activated alumina, lithium feldspar and Guangxi white clay according to the proportion, add them together with the wet granules obtained in S1 into the mixer and mix for 20 min to 30 min to obtain the matrix layer mixture. S3. Weigh out the raw materials for the fabric layer, including high-purity SiC-Si3N4, zircon mullite, lithium feldspar, activated alumina, and Guangxi white clay, according to the proportion. Put them into a mixer and mix for 10-20 minutes. After mixing, add water and binder and mix again for 10-15 minutes to obtain the wet powder of the fabric layer. S4. The matrix layer mixture and the wet powder of the face layer, which are evenly mixed in S2 and S3, are aged at room temperature and placed in a cool and dry place for 24h~48h. After aging, the matrix layer green material and the face layer green material are obtained. S5. The prepared fabric layer green blank is laid flat on the inner wall of the bottom of the reactor corresponding to the position of the mold, and then the prepared matrix layer green blank is loaded into the mold. After pressing, drying, firing and cooling, the double-layer composite reactor is obtained.

9. The preparation method according to claim 8, characterized in that, In step S1, based on the total mass of the cordierite and the mullite, the mass percentage of the binder and the water is 5%, and the ratio of the binder to the water is 4:

1.

10. The preparation method according to claim 8, characterized in that, The pressing process involves pressing a mold containing the base layer green blank and the fabric layer green blank using a hydraulic press for 10s to 15s to obtain a blank. The drying process includes placing the pressed blank into a drying chamber with an initial temperature of 30°C to 50°C for 2 to 3 hours, gradually raising the temperature to 80°C to 100°C, and then drying for another 4 to 6 hours until the moisture content is 0.5% to 0.8%. The firing and cooling process involves placing the dried green body into a high-temperature kiln, heating it at ≤5℃ / min to 1350℃~1400℃ for 12h~16h, and then cooling it to room temperature to obtain the reactor.