Method for improving sintering quality of lithium battery positive electrode material by using insulating refractory

Abstract

The application provides a method for improving sintering quality of lithium battery positive electrode material by using an insulating refractory, and the method comprises the following steps: forming an insulating material by using a cerium-doped lanthanum zirconate solid solution and a high-temperature binder, spraying the insulating material on the surface of the kiln wall and the kiln roof refractory of a sintering kiln to obtain a sintering kiln with the insulating refractory; compared with a conventional sintering kiln, the sintering kiln with the insulating refractory can isolate the pollution of metal ions in the refractory to the positive electrode material, and can also isolate the erosion and corrosion of the alkaline compound of the positive electrode material to the refractory, so that the qualified rate of the sintered positive electrode material is increased by more than 10%, the energy saving of per ton of positive electrode material is more than 15%, and the service life of the sintering kiln is increased by more than one time. The insulating material is applied to the sintering kiln for the lithium battery positive electrode material, and the bottleneck problem that has plagued the sintering of the positive electrode material is solved.

Description

Technical Field

[0001] This invention relates to the field of lithium batteries, and in particular to a method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials. Background Technology

[0002] In 1987, Akira Yoshino developed the earliest lithium-ion secondary battery model using LiCoO2 as the positive electrode and graphite as the negative electrode. This technology was eventually adopted by Sony, which launched the world's first commercial lithium-ion battery in 1991. In 1996 and 1997, Japan and the United States successively developed olivine-structured LiFePO4 positive electrode materials. Compared with other positive-valent materials, LiFePO4 is readily available, inexpensive, and pollution-free. Because lithium secondary batteries solved the safety performance problem of lithium batteries and reduced manufacturing costs, with a battery operating voltage exceeding 3.5V and a specific energy reaching 120Wh / kg, they immediately attracted widespread research and attention globally. After nearly two decades of technological improvement and progress, lithium-ion batteries have become the preferred chemical power source and are widely used in energy storage and power systems.

[0003] The application fields of lithium batteries are gradually expanding, and the demand is constantly increasing. The performance of cathode materials is a crucial factor limiting the capacity of lithium batteries. Commonly used lithium battery cathode materials mainly include olivine-type LiFePO4, layered LiCoO2, spinel-type LiMn2O4, and ternary materials LiNi. 1-x-y Co x M y O2 (M = Mn, Al), etc. The working principle of a lithium-ion battery is that during charging, lithium ions are extracted from the positive electrode material's crystal lattice and inserted into the negative electrode material's crystal lattice through the electrolyte. During discharging, lithium ions are extracted from the negative electrode material's crystal lattice and inserted into the positive electrode material's crystal lattice through the electrolyte. The positive electrode material for lithium-ion batteries is prepared by high-temperature sintering via solid-state or precipitation methods. The high-temperature sintering furnace has a crucial impact on the quality of the positive electrode material. Commonly used sintering furnaces include pusher furnaces, roller furnaces, and rotary furnaces, with operating temperatures ranging from room temperature to 1050℃. Currently, the sintering of positive electrode materials in lithium batteries mainly uses sagger stacking and sintering, primarily in roller furnaces and pusher furnaces.

[0004] Lithium-ion battery cathode materials undergo complex chemical reactions during high-temperature sintering. Particularly in industrial production, issues such as temperature stability within the sintering kiln, contamination of the cathode material by refractory metal ions, and corrosion or erosion of the kiln refractory material by gases released during the cathode material reaction and alkaline lithium oxide contribute to bottlenecks that make it difficult to provide stable cathode material products in industrial production. During production, achieving ideal temperature field uniformity within the kiln is challenging, resulting in cathode materials that cannot meet the requirements of high-end lithium-ion batteries. For example, at high temperatures, cathode materials must undergo the release of free water, crystal water, and gases, as well as decomposition, synthesis, and crystal formation. Excessive temperature differences across the kiln cross-section in the high-temperature zone can lead to over-burning and particle agglomeration of the cathode material at higher temperatures or near the edge of the sagger, while incomplete reactions occur at lower temperatures or in the middle of the sagger. This makes it difficult to guarantee product consistency in industrial production. The uniformity of the kiln temperature field has a significant impact on the final performance of the cathode material. Erosion of the kiln refractory material is due to the complex physicochemical reactions occurring in the cathode material at high temperatures, involving Li₂CO₃ and Li₂. O reacts with compounds such as SiO2 and Al2O3 in refractory materials to form low-melting eutectic lithium silicate and lithium aluminate compounds, causing corrosion. At high temperatures, refractory materials release some metal ions, which are suspended in the hot gas inside the kiln. Some of these metal ions react with the cathode material. Additionally, as the cathode material enters the cooling section, some of the suspended metal ions fall onto the surface of the cathode material in the sagger, such as chromium, copper, iron, and zinc impurities. When the battery voltage reaches the redox potential of these metal elements, these metals oxidize at the cathode and then reduce at the anode. The metal deposited at the anode easily damages the separator, causing battery self-discharge. Simultaneously, the cathode material struggles to achieve the required specific capacity, conductivity, and other performance indicators. Currently, the bottleneck hindering the industrialization of lithium battery cathode materials through high-temperature sintering is solving the problems of kiln temperature field uniformity, energy saving and consumption reduction, refractory material corrosion, and contamination of the cathode material. Summary of the Invention

[0005] In view of this, the present invention aims to propose a method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials. This method solves the bottleneck problems of temperature field uniformity in high-temperature sintering kilns, erosion and corrosion of refractory materials, and pollution of cathode materials that hinder the industrialization of lithium battery cathode materials. It improves the specific capacity, conductivity and other performance indicators of cathode materials, and achieves energy saving, consumption reduction and extended service life of sintering kilns.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials, the method comprising the following steps:

[0008] (1) Preparation of insulating materials

[0009] Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate were mixed according to La2(Zr) 1-x Ce x The stoichiometric ratio of 2O7 is uniformly mixed, where x = 0.2-0.8. At an ignition temperature of 1400℃-1500℃, a cerium-doped lanthanum zirconate solid solution powder is formed. The powder is added to a mixture of water and dispersant, where the mass ratio of powder to water is (1.2-2):1. The amount of dispersant added is 3‰-1% of the powder. The slurry particle size is then ground to D. (90) ≤10.0μm, then the slurry and high-temperature binder are mixed evenly at a ratio of 1:(0.8-1.5) to obtain the insulating material;

[0010] (2) Refractory materials for isolating sintering kilns

[0011] A layer of insulating material is sprayed onto the surface of the refractory material with a thickness of 0.2-0.4 mm. After drying at room temperature, the temperature is raised according to the drying program of the sintering kiln, and the maximum temperature reaches 1250℃ and is held for 4 hours. The insulating material and the refractory material are firmly bonded together, resulting in a sintering kiln with insulating refractory material.

[0012] (3) Sintering of cathode materials

[0013] The crucible containing the raw materials for the positive electrode of lithium batteries is placed into a sintering kiln insulated with refractory materials. The materials pass through a preheating zone, a high-temperature zone, and a cooling zone to obtain the positive electrode material powder.

[0014] Furthermore, the dispersant is one or a mixture of two or more of BYK190, RT-8040, and RT-8022.

[0015] Furthermore, the high-temperature binder is Al(H2PO4)3.

[0016] Furthermore, in step (2), before spraying the insulating material, the refractory mud and dust on the surface of the refractory material of the kiln wall and kiln roof of the sintering kiln are removed.

[0017] Furthermore, in step (3), the temperature of the high-temperature zone of the sintering kiln for isolating refractory materials is controlled at 800℃-850℃.

[0018] Furthermore, in step (2), the sintering kiln is a pusher kiln or a roller kiln.

[0019] Furthermore, in step (3), the lithium battery cathode raw materials include LiCoO2, LiMn2O4, LiFePO4, and LiNi. 1-x- y Co x M y O2, where M = Mn, Al.

[0020] The core of the method of this invention is: 1) Ce 4+ The structure of doped La2Zr2O7 solid solutions varies with the Ce content in the solid solution. 4+ and Zr 4+ The Zr mass ratio changes with the mass ratio. 4+ When the proportion is low, Zr 4+ Entering the CeO2 lattice, it causes lattice distortion and defects, enhances the mobility of lattice oxygen vacancies, and forms a cubic fluorite-structured lanthanum cerium zirconate solid solution; with Zr 4+ As the proportion gradually increases, the content of the cubic phase, dominated by CeO2, decreases, while the content of the tetragonal phase, dominated by ZrO2, increases; Ce 4+ Lanthanum cerium zirconate solid solution enters the ZrO2 lattice to form a tetragonal phase. 4+ Entering the ZrO2 lattice facilitates the formation of a tetragonal lanthanum cerium zirconate solid solution with good thermal stability. Lanthanum in the solid solution inhibits the high-temperature sintering of the powder. The resulting lanthanum cerium zirconate solid solution improves the high-temperature thermal stability of the insulating material, leading to an increase in the infrared emissivity and a decrease in the thermal conductivity of the insulating material. 2) The insulating material is tightly bonded to the refractory material and forms a glaze, which isolates the metal ions released by the refractory material from contaminating the cathode material, and isolates the corrosive gases and alkaline compounds produced by the cathode material reaction from eroding the refractory material. The glaze also has functions such as corrosion resistance, wear resistance, and thermal barrier. 3) The radiation function of the insulating material significantly enhances the radiative heat transfer of the sintering kiln and improves the uniformity of the temperature field inside the kiln. According to the Stefan-Boltzmann law, the heat transferred from the insulating material to the cathode material inside the kiln is proportional to the fourth power of the absolute temperature of the insulating material. Spraying the insulating material significantly enhances the heating energy of the cathode material. 4) The insulating material changes the spectral distribution of infrared radiation inside the kiln, transforming the intermittent spectrum into a continuous spectrum. The emitted far-infrared rays directly penetrate into the interior of the cathode material, causing molecular oscillations inside the material, generating energy level transitions, and radiating infrared rays of a certain wavelength, thereby generating heat. The material is heated uniformly from the inside out, shortening the material reaction time and improving the uniformity of the components in the material.

[0021] Compared with existing technologies, the method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials as described in this invention has the following advantages:

[0022] (1) The present invention uses cerium-doped lanthanum zirconate solid solution and high-temperature binder to form an insulating material, which has excellent stability in high-temperature, reducing, oxidizing and alkaline compound environments, significantly enhances the corrosion and erosion resistance of sintering kiln, extends the service life of sintering kiln and solves the problem of sintering kiln.

[0023] (2) The material of the present invention is closely bonded to the refractory material and forms a glaze on the surface of the refractory material, which effectively isolates the corrosive gases and alkaline compounds generated during the reaction process of the positive electrode material from the refractory material, avoiding erosion and corrosion of the refractory material, while enhancing the wear resistance of the inner wall and shielding the metal ions in the refractory material from contamination of the positive electrode material.

[0024] (3) The La2(Zr) of this invention 1-x Ce x 2O7 is a thermal barrier material. Its coefficient of thermal expansion is matched with that of refractory materials. It also has a low thermal conductivity, which provides insulation and reduces the temperature of the outer wall of the sintering kiln, thus effectively reducing energy consumption.

[0025] (4) The La2(Zr) of this invention 1-x Ce x )2O7 has a high infrared emissivity, which improves the uniformity of the temperature field in the sintering kiln, promotes the uniform reaction of the cathode material, and realizes the homogenization of cathode material composition and complete reaction.

[0026] (5) The far-infrared rays emitted by the insulating material of the present invention can penetrate into the unburned particles in the smoke and dust, heat their interior and achieve complete combustion, thereby reducing the content of unburned dust in the smoke and dust.

[0027] (6) The far-infrared rays emitted by the insulating material of the present invention can directly penetrate into the interior of the positive electrode material for heating reaction, which significantly shortens the reaction time of the positive electrode material and significantly improves the production capacity compared with conventional sintering kilns of the same model.

[0028] (7) The present invention makes it easy to spray the insulating material in both newly built sintering kilns and existing sintering kilns. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0030] The present invention will now be described in detail with reference to embodiments.

[0031] Example 1

[0032] A method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials, the method comprising the following steps:

[0033] (1) Preparation of insulating material: Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate are mixed uniformly in stoichiometric ratio and calcined at 1500℃ to form La2(Zr) 0.8 Ce 0.2)2O7 powder, 200 parts of the powder are added to a mixed solution of 100 parts of water and 1.1 parts of dispersant, and the slurry particle size is ground to D by grinding. (90) After the thickness reaches 10.0 μm, the slurry is transferred to a dispersion tank, and 300 parts of Al(H2PO4)3 solution are slowly added and mixed evenly to obtain the insulating material.

[0034] (2) Isolation of refractory material in pusher kiln: Remove refractory mud and dust from the surface of the refractory material on the kiln wall and kiln roof of the pusher kiln, spray a layer of isolation material on the surface of the refractory material with a spray thickness of 0.3 mm, and after drying at room temperature, raise the temperature according to the drying program of the pusher kiln, and keep it at the maximum temperature of 1250℃ for 4 hours. The isolation material and the refractory material are firmly bonded together to obtain a pusher kiln with isolation refractory material.

[0035] (3) Sintering of cathode material: The temperature of the high-temperature zone of the pusher kiln for insulating refractory material is controlled at 850℃. The sagger containing LiCoO2 raw material is put into the pusher kiln for insulating refractory material. The layered LiCoO2 cathode material is obtained by passing through the preheating zone, the high-temperature zone and the cooling zone.

[0036] (4) Performance comparison analysis: Compared with conventional pusher kilns, pusher kilns that isolate refractory materials isolate the contamination of LiCoO2 by metal ions in refractory materials, and also isolate the erosion and corrosion of refractory materials by alkaline compounds in LiCoO2. The qualified rate of sintered LiCoO2 products is increased by 10.5%, energy is saved by 15.6% per ton of LiCoO2, and the service life of pusher kilns is increased by 1.5 times.

[0037] Example 2

[0038] A method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials, the method comprising the following steps:

[0039] (1) Preparation of insulating material: Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate are mixed uniformly in stoichiometric ratio and calcined at 1500℃ to form La2(Zr) 0.6 Ce 0.4 )2O7 powder, 200 parts of the powder are added to a mixed solution of 100 parts of water and 1.1 parts of dispersant, and the slurry particle size is ground to D by grinding. (90) After the thickness reaches 10.0 μm, the slurry is transferred to a dispersion tank, and 300 parts of Al(H2PO4)3 solution are slowly added and mixed evenly to obtain the insulating material.

[0040] (2) Isolation of refractory material in roller kiln: Remove refractory mud and dust from the surface of the refractory material on the kiln wall and kiln roof of the roller kiln, spray a layer of isolation material on the surface of the refractory material with a spray thickness of 0.3 mm, dry at room temperature, and then heat up according to the drying program of roller kiln, with the maximum temperature reaching 1250℃ and holding for 4 hours. The isolation material and the refractory material are firmly bonded together to obtain a roller kiln with isolation refractory material.

[0041] (3) Sintering of cathode material: The temperature of the high-temperature zone of the roller kiln for insulating refractory material is controlled at 840℃. The sagger containing LiMn2O4 raw material is put into the roller kiln for insulating refractory material. After passing through the preheating zone, high-temperature zone and cooling zone, spinel-type LiMn2O4 cathode material is obtained.

[0042] (4) Performance comparison analysis: Compared with conventional roller kilns, roller kilns that isolate refractory materials isolate the contamination of LiMn2O4 by metal ions in refractory materials, and also isolate the erosion and corrosion of refractory materials by alkaline compounds in LiMn2O4. The qualified rate of sintered LiMn2O4 products is increased by 15.6%, energy is saved by 16.1% per ton of LiMn2O4, and the service life of roller kilns is increased by 1.8 times.

[0043] Example 3

[0044] A method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials, the method comprising the following steps:

[0045] (1) Preparation of insulating material: Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate are mixed uniformly in stoichiometric ratio and calcined at 1400℃ to form La2(Zr) 0.4 Ce 0.6 )2O7 powder, 200 parts of the powder are added to a mixed solution of 130 parts of water and 1 part of dispersant, and the slurry particle size is ground to D by grinding. (90) After the thickness reaches 10.0 μm, the slurry is transferred to a dispersion tank, and 330 parts of Al(H2PO4)3 solution are slowly added and mixed evenly to obtain the insulating material.

[0046] (2) Isolation of refractory material in pusher kiln: Remove refractory mud and dust from the surface of the refractory material on the kiln wall and kiln roof of the pusher kiln, spray a layer of isolation material on the surface of the refractory material with a spray thickness of 0.3 mm, and after drying at room temperature, raise the temperature according to the drying program of the pusher kiln, and keep it at the maximum temperature of 1250℃ for 4 hours. The isolation material and the refractory material are firmly bonded together to obtain a pusher kiln with isolation refractory material.

[0047] (3) Sintering of cathode material: The temperature of the high-temperature zone of the pusher kiln for insulating refractory material is controlled at 800℃. The sagger containing LiFePO4 raw material is put into the pusher kiln for insulating refractory material. After passing through the preheating zone, high-temperature zone and cooling zone, olivine-type LiFePO4 cathode material is obtained.

[0048] (4) Performance comparison analysis: Compared with conventional pusher kilns, pusher kilns that isolate refractory materials isolate the contamination of LiFePO4 by metal ions in refractory materials, and also isolate the erosion and corrosion of refractory materials by alkaline compounds in LiFePO4. The qualified rate of sintered LiFePO4 products is increased by 16.7%, energy is saved by 17.2% per ton of LiFePO4, and the service life of pusher kilns is increased by 2.0 times.

[0049] Example 4

[0050] A method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials, the method comprising the following steps:

[0051] (1) Preparation of insulating material: Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate are mixed uniformly in stoichiometric ratio and calcined at 1400℃ to form La2(Zr) 0.2 Ce 0.8 )2O7 powder, 200 parts of the powder are added to a mixed solution of 130 parts of water and 1 part of dispersant, and the slurry particle size is ground to D by grinding. (90) After the thickness reaches 10.0 μm, the slurry is transferred to a dispersion tank, and 330 parts of Al(H2PO4)3 solution are slowly added and mixed evenly to obtain the insulating material.

[0052] (2) Isolation of refractory material in roller kiln: Remove refractory mud and dust from the surface of the refractory material on the kiln wall and kiln roof of the roller kiln, spray a layer of isolation material on the surface of the refractory material with a spray thickness of 0.3 mm, dry at room temperature, and then heat up according to the drying program of roller kiln, with the maximum temperature reaching 1250℃ and holding for 4 hours. The isolation material and the refractory material are firmly bonded together to obtain a roller kiln with isolation refractory material.

[0053] (3) Sintering of positive electrode material: The temperature of the high-temperature zone of the roller kiln for insulating refractory material is controlled at 850℃, and the LiNi is packed with positive electrode material. 1-x-y Co x M y O2 (M=Mn,Al) raw material is fed into a roller kiln containing refractory material, passing through a preheating zone, a high-temperature zone, and a cooling zone to obtain the ternary material LiNi. 1-x-y Co x M y O2 cathode material;

[0054] (4) Performance Comparison Analysis: Compared with conventional roller kilns, roller kilns that isolate refractory materials isolate the metal ions in the refractory materials from LiNi. 1-x-y Co x M y O2 pollution, while also isolating LiNi 1-x-y Co x M y The erosion and corrosion of refractory materials by alkaline compounds in O2, and the sintering of LiNi 1-x-y Co x M y The pass rate of O2 products increased by 20.6%, and the pass rate of each ton of LiNi was [missing information 1-x-y Co x M y O2 saves 18.5% of energy and increases the service life of roller kilns by 2.2 times.

[0055] Comparative Example 1

[0056] (1) Preparation of insulating material: Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate are mixed uniformly in stoichiometric ratio and calcined at 1200℃ to form La2(Zr) 0.8 Ce 0.2 )2O7 powder, 200 parts of the powder are added to a mixed solution of 100 parts of water and 1.1 parts of dispersant, and the slurry particle size is ground to D by grinding. (90) After the thickness reaches 10.0 μm, the slurry is transferred to a dispersion tank, and 300 parts of Al(H2PO4)3 solution are slowly added and mixed evenly to obtain the insulating material.

[0057] (2) Performance comparison analysis: Compared with conventional pusher kilns, pusher kilns that isolate refractory materials isolate the contamination of LiCoO2 by metal ions in refractory materials, and also isolate the erosion and corrosion of refractory materials by alkaline compounds in LiCoO2. The qualified rate of sintered LiCoO2 products is increased by 7.2%, energy is saved by 9.8% per ton of LiCoO2, and the service life of pusher kilns is increased by 0.4 times.

[0058] Comparative Example 2

[0059] (1) Preparation of insulating material: Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate are mixed uniformly in stoichiometric ratio and calcined at 1500℃ to form La2(Zr) 0.6 Ce 0.4 )2O7 powder, 200 parts of the powder are added to a mixed solution of 100 parts of water and 1.1 parts of dispersant, and the slurry particle size is ground to D by grinding. (90) After the thickness reaches 10.0 μm, the slurry is transferred to a dispersion tank, and 200 parts of Al(H2PO4)3 solution are slowly added and mixed evenly to obtain the insulating material.

[0060] (2) Performance comparison analysis: Compared with conventional roller kilns, roller kilns that isolate refractory materials isolate the contamination of LiMn2O4 by metal ions in refractory materials, and also isolate the erosion and corrosion of refractory materials by alkaline compounds in LiMn2O4. The qualified rate of sintered LiMn2O4 products is increased by 8.7%, energy is saved by 11.1% per ton of LiMn2O4, and the service life of roller kilns is increased by 0.6 times.

[0061] Comparative Example 3

[0062] (1) Preparation of insulating material: Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate are mixed uniformly in stoichiometric ratio and calcined at 1400℃ to form La2(Zr) 0.4 Ce 0.6 )2O7 powder, 200 parts of the powder are added to a mixed solution of 250 parts of water and 1 part of dispersant, and the slurry particle size is ground to D by grinding. (90) After the thickness reaches 10.0 μm, the slurry is transferred to a dispersion tank, and 330 parts of Al(H2PO4)3 solution are slowly added and mixed evenly to obtain the insulating material.

[0063] (2) Performance comparison analysis: Compared with conventional pusher kilns, pusher kilns that isolate refractory materials isolate the contamination of LiFePO4 by metal ions in refractory materials, and also isolate the erosion and corrosion of refractory materials by alkaline compounds in LiFePO4. The qualified rate of sintered LiFePO4 products is increased by 8.7%, energy is saved by 11.1% per ton of LiFePO4, and the service life of pusher kilns is increased by 0.6 times.

[0064] Comparative Example 4

[0065] (1) Preparation of insulating material: Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate are mixed uniformly in stoichiometric ratio and calcined at 1400℃ to form La2(Zr) 0.2 Ce 0.8 )2O7 powder, 200 parts of the powder are added to a mixed solution of 130 parts of water and 0.4 parts of dispersant, and the slurry particle size is ground to D by grinding. (90) After the thickness reaches 10.0 μm, the slurry is transferred to a dispersion tank, and 330 parts of Al(H2PO4)3 solution are slowly added and mixed evenly to obtain the insulating material.

[0066] (2) Performance Comparison Analysis: Compared with conventional roller kilns, roller kilns that isolate refractory materials isolate the metal ions in the refractory materials from LiNi. 1-x-y Co x M y O2 pollution, while also isolating LiNi 1-x-y Co x M yThe erosion and corrosion of refractory materials by alkaline compounds in O2, and the sintering of LiNi 1-x-y Co x M y The O2 product qualification rate increased by 12.5%, and the per ton of LiNi 1-x-y Co x M y O2 saves 14.1% of energy and increases the service life of roller kilns by 0.9 times.

[0067] Table 1 Comparison of results from Examples 1-4

[0068]

[0069]

[0070] Table 2 Comparison of results from Examples 1-4

[0071]

[0072] The above comparison reveals that, compared with conventional sintering kilns, the sintering kiln that isolates refractory materials prevents the contamination of the cathode material by metal ions in the refractory material, and also prevents the erosion and corrosion of the refractory material by alkaline compounds in the cathode material. In the examples 1-4 of this invention, the qualified rate of sintered cathode material products is increased by more than 10%, energy is saved by more than 15% per ton of cathode material, and the service life of the sintering kiln is increased by more than 100%. In Comparative Example 1, lowering the powder calcination temperature resulted in incomplete calcination, leading to a decrease in the improvement rate of sintered LiCoO2 product qualification, energy savings per ton of LiCoO2, and the increase in the service life of the pusher kiln. In Comparative Example 2, reducing the amount of binder caused coating cracking, resulting in a decrease in the improvement rate of sintered LiMn2O4 product qualification, energy savings per ton of LiMn2O4, and the increase in the service life of the roller kiln. In Comparative Example 3, increasing the amount of water reduced the coating density, resulting in a decrease in the energy savings per ton of LiFePO4 and the increase in the service life of the pusher kiln. In Comparative Example 4, reducing the amount of dispersant resulted in uneven powder dispersion in water, leading to a decrease in the LiNi... 1-x- y Co x M y Both the energy saving rate of O2 and the increase in the service life of roller kilns have decreased.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials, characterized in that: The method includes the following steps: (1) Preparation of insulating materials Lanthanum carbonate, cerium carbonate, and zirconium oxycarbonate were mixed according to La2(Zr) 1-x Ce x The stoichiometric ratio of 2O7 is uniformly mixed, where x = 0.2-0.

8. At an ignition temperature of 1400℃-1500℃, a cerium-doped lanthanum zirconate solid solution powder is formed. The powder is added to a mixture of water and dispersant, where the mass ratio of powder to water is (1.2-2):

1. The amount of dispersant added is 3‰-1% of the powder mass. The slurry particle size is then ground to D. (90) ≤10.0μm, then the slurry and high-temperature binder are mixed evenly at a ratio of 1:(0.8-1.5) to obtain the insulating material; (2) Refractory materials for isolating sintering kilns A layer of insulating material is sprayed onto the surface of the refractory material with a thickness of 0.2-0.4 mm. After drying at room temperature, the temperature is raised according to the drying program of the sintering kiln, and the maximum temperature reaches 1250℃ and is held for 4 hours. The insulating material and the refractory material are firmly bonded together, resulting in a sintering kiln with insulating refractory material. (3) Sintering of cathode materials The crucible containing the raw materials for the positive electrode of lithium batteries is placed into a sintering kiln insulated with refractory materials. The material passes through a preheating zone, a high-temperature zone, and a cooling zone to obtain the positive electrode material powder.

2. The method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials according to claim 1, characterized in that: The dispersant is one or a mixture of two or more of BYK190, RT-8040, and RT-8022.

3. The method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials according to claim 1, characterized in that: The high-temperature binder is Al(H2PO4)3.

4. The method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials according to claim 1, characterized in that: In step (2), before spraying the insulating material, the refractory mud and dust on the surface of the refractory material of the kiln wall and kiln roof of the sintering kiln are removed.

5. The method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials according to claim 1, characterized in that: In step (3), the temperature of the high-temperature zone of the sintering kiln for isolating refractory materials is controlled at 800℃-850℃.

6. The method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials according to claim 1, characterized in that: In step (2), the sintering kiln is either a pusher kiln or a roller kiln.

7. The method for improving the sintering quality of lithium battery cathode materials by isolating refractory materials according to claim 1, characterized in that: In step (3), the raw material for the lithium battery cathode is LiCoO2, LiMn2O4, LiFePO4, or LiNi. 1-x-y Co x M y O2, where M = Mn, Al.

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