Metal oxide precursors, their manufacturing methods, and applications

Abstract

This application discloses a metal oxide precursor, a method for producing the same, and its applications. The metal oxide precursor comprises dispersed single-crystal particles and aggregate particles that are partly composed of single-crystal particles, and the degree of dispersion K of the metal oxide precursor is 0.467-0.917, and K=D 50 / (η×D 90 ) and here, D 50 This is the particle size that corresponds to the point when the cumulative particle size distribution percentage of the metal oxide precursor reaches 50%, and D 90 η is the particle size corresponding to when the cumulative particle size distribution of the metal oxide precursor reaches 90%, and η is the volume deviation coefficient, where η = 0.6. The metal oxide precursor described in the embodiment of this application has a high degree of dispersion and specific surface area, and can be used directly in the manufacture of cathode materials without processing such as polishing or crushing, resulting in good uniformity of the manufactured cathode material and high stability in performance tests.

Description

Cross-reference of related applications

[0001] This application requests priority from the Chinese patent application filed with the China National Intellectual Property Office on December 29, 2023, application number 202311871680X, with the title of invention "Metal Oxide Precursor, Method for Producing the Same, and Applications," the entire contents of which are incorporated into this application by reference. [Technical Field]

[0002] This application relates to the field of battery technology, and more particularly to metal oxide precursors, their manufacturing methods, and applications. [Background technology]

[0003] The descriptions herein provide only background information relating to the present invention and do not necessarily constitute prior art. Metal oxide precursors produced by conventional spray pyrolysis methods typically exhibit severe aggregation phenomena, resulting in a low specific surface area, low sintering activity during the sintering process of the cathode material, increased energy consumption, and high production costs. Therefore, aggregation phenomena of metal oxide precursors produced by conventional spray pyrolysis methods are usually improved by adding surfactants or by polishing or crushing the metal oxide precursors. However, these methods not only increase costs and decrease production efficiency but also affect the stability of performance tests of the cathode material. Therefore, there is a need to provide highly dispersible metal oxide precursors that can be used directly in the manufacture of cathode materials without requiring processing such as polishing or crushing. [Overview of the Initiative]

[0004] One of the objectives of the embodiments of this application is to provide a metal oxide precursor, a method for producing the same, and its applications, with the aim of providing a highly dispersible metal oxide precursor that can be used directly in the manufacture of cathode materials without requiring processing such as polishing or crushing.

[0005] The technical solutions employed in the embodiments of this application are as follows: In the first aspect, a metal oxide precursor is provided, and the metal oxide precursor includes single crystal particles in a dispersed state and aggregate particles partially composed of single crystal particles. The dispersion degree K of the metal oxide precursor is 0.467 - 0.917, and K = D 50 / (η × D 90 ), where D 50 is the particle size corresponding to when the cumulative particle size distribution percentage of the metal oxide precursor reaches 50%, and D 90 is the particle size corresponding to when the cumulative particle size distribution percentage of the metal oxide precursor reaches 90%, and η is the volume deviation coefficient, and η = 0.6.

[0006] In one example, 1.5 μm ≤ D 50 ≤ 4.0 μm.

[0007] In one example, 4 μm ≤ D 90 ≤ 10 μm.

[0008] In one example, the dispersion degree K of the metal oxide precursor is 0.5 - 0.9.

[0009] In one example, the dispersion degree K of the metal oxide precursor is 0.6 - 0.8.

[0010] In one example, the specific surface area of the metal oxide precursor is 4 m 2 / g - 12 m 2 / g.

[0011] In one example, the loose bulk density of the metal oxide precursor is 0.4 g / cm 3 - 1.2 g / cm 3 .

[0012] In one example, the tap density of the metal oxide precursor is 1.0 g / cm 3 - 2.5 g / cm 3 .

[0013] In one embodiment, the equivalent diameter of the aggregate particles is 5 to 30 times the particle size of the single crystal particles.

[0014] In one embodiment, the degree of dispersion of a single aggregate particle in the metal oxide precursor is K = S2 / nS1, where S1 is the surface area of ​​a single single crystal particle in the aggregate particle, n is the number of single crystal particles in the aggregate particle, and S2 is the surface area of ​​the aggregate particle.

[0015] In one embodiment, the general chemical formula of the metal oxide precursor is Mn a M 1-a It is represented as O2, where 0.1 ≤ a ≤ 0.9, and M is at least one selected from Ni, Fe, Cu, Zn, Co, Mg, Al, and Ti.

[0016] In one example, the metal content of the metal oxide precursor is 70% or more.

[0017] In a second embodiment, the present invention provides a method for producing a metal oxide precursor selected from a spray pyrolysis method.

[0018] In one embodiment, the thermal decomposition temperature of the spray pyrolysis method is 500°C-1000°C.

[0019] In one embodiment, the frequency of the supply device for the spray pyrolysis method is 25Hz-45Hz.

[0020] In one embodiment, the flow rate of the supply device for the spray pyrolysis method is 0.3 m³. 3 / h-0.7m 3 It is / h.

[0021] In a third embodiment, the present application provides a positive electrode material manufactured from the metal oxide precursor described above or from a metal oxide precursor manufactured by the method described above.

[0022] In a fourth embodiment, the present invention provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode material layer provided on the surface of the positive electrode current collector and containing the positive electrode material.

[0023] In a fifth embodiment, the present application provides a secondary battery including the above-described positive electrode sheet.

[0024] The beneficial effects of the metal oxide precursor according to the embodiment of this application are as follows: When the dispersion degree K of the metal oxide precursor is 0.467-0.917, and the metal oxide precursor is at this specific dispersion degree, on the one hand, the aggregation phenomenon of the metal oxide precursor is effectively reduced, and it can be used directly in the manufacture of cathode materials without the need for processing such as polishing or crushing. Even if some aggregate particles are present, the metal oxide precursor has a certain degree of dispersion, so the aggregate particles are easily dispersed during the process of manufacturing the cathode material. This is advantageous for improving the uniformity effect of the mixed material, resulting in good consistency of the manufactured cathode material, which is advantageous for improving the stability of performance testing of the cathode material, as well as for reducing costs and improving production efficiency. On the other hand, the metal oxide precursor has a relatively high specific surface area, which is advantageous for improving the sintering activity of the metal oxide precursor during the manufacturing process of the cathode material, and reduces production energy consumption.

[0025] The beneficial effects of the method for producing metal oxide precursors according to the embodiments of this application are as follows: It can be produced by spray pyrolysis, and the dispersion degree K of the produced metal oxide precursor is 0.467-0.917, which effectively reduces the aggregation phenomenon of the metal oxide precursor and allows it to be used directly in the production of cathode materials without the need for processing such as polishing or crushing. At the same time, the metal oxide precursor has a relatively high specific surface area, which is advantageous for improving the sintering activity of the metal oxide precursor in the production process of cathode materials and reduces production energy consumption.

[0026] The beneficial effects of the cathode material according to the embodiment of this application are as follows: By using the metal oxide precursor of the embodiment of this application in the manufacture of the cathode material, a single-crystal cathode material with good uniformity can be obtained more easily, which is advantageous for improving the discharge capacity and cycle performance of the cathode material.

[0027] The beneficial effects of the positive electrode sheet according to the embodiment of the present application are as follows: Because the positive electrode material layer of the positive electrode sheet according to the embodiment of the present application contains a positive electrode material that improves the discharge capacity and cycle performance, the electrochemical performance of the positive electrode sheet, such as energy density and cycle stability, is improved.

[0028] The beneficial effects of the secondary battery according to the embodiment of the present invention are as follows. The embodiment of the present invention can improve the electrochemical performance of the secondary battery, such as cycle stability and cycle life, by applying a positive electrode sheet having characteristics such as high energy density and cycle stability to the secondary battery. [Brief explanation of the drawing]

[0029] To more clearly explain the technical concepts in the embodiments of this application, the following briefly introduces the drawings that may be used to describe the embodiments or exemplary technologies. Clearly, the drawings in the following description represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these without any creative effort.

[0030] Figure 1 is a scanning electron microscope image of a metal oxide precursor according to Example 1 of the present invention.

[0031] Figure 2 is a scanning electron microscope image of the metal oxide precursor according to Example 2 of the present invention.

[0032] Figure 3 is a scanning electron microscope image of the metal oxide precursor according to Comparative Example 1 of the present invention.

[0033] Figure 4 is a scanning electron microscope image of the metal oxide precursor according to Comparative Example 2 of the present invention. [Modes for carrying out the invention]

[0034] To further clarify the purpose, technical solutions, and advantages of this application, the application will be described in more detail below with reference to the drawings and embodiments. The specific embodiments described herein are for interpretation purposes only and do not limit the application.

[0035] Furthermore, when a component is referred to as being "fixed" or "attached" to another component, it may be attached to the other component directly or indirectly. When one component is referred to as being "connected" to another component, it may be connected to the other component directly or indirectly. The directions or positional relationships indicated by terms such as "up," "down," "left," and "right" are based on the directions or positional relationships shown in the drawings and are merely for the purpose of facilitating explanation. They do not indicate or imply that the specified device or element has a specific direction or must be configured and operated in a specific direction, and therefore cannot be understood as limiting this application. A person skilled in the art can understand the specific meaning of the above terms depending on the specific situation. The terms "first" and "second" are merely for the purpose of facilitating explanation and do not indicate or imply relative importance or implicitly indicate the number of technical features. "Multiple" means two or more unless otherwise specified.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art relating to the embodiments of this application. Terms used in the description of the embodiments of this application are solely for the purpose of describing specific embodiments or examples and are not intended to limit the embodiments of this application. The selectable range of the term "and / or" as used herein includes any one of two or more related column items, and any and all combinations of related column items, including any two, any more, related column items, or any combination of all related column items.

[0037] To explain the technical proposal of this application, a detailed description will be provided below with reference to specific drawings and embodiments.

[0038] Some embodiments of the present application provide a metal oxide precursor comprising dispersed single crystal particles and aggregate particles consisting partly of single crystal particles. The degree of dispersion K of the metal oxide precursor is 0.467-0.917, and K=D 50 / (η×D 90 ) and here, D 50 This is the particle size that corresponds to when the cumulative particle size distribution percentage of the metal oxide precursor reaches 50%, and D 90 η is the particle size corresponding to the point when the cumulative particle size distribution percentage of the metal oxide precursor reaches 90%, and η is the volume deviation coefficient, where η = 0.6.

[0039] Theoretically, if aggregation does not occur, the metal oxide precursor will have the maximum specific surface area. If local aggregation occurs between particles, the tighter the gaps between aggregated particles, the more severe the aggregation and the smaller the specific surface area.

[0040] Based on this, the embodiments of the present application define the degree of dispersion K of a metal oxide precursor as the ratio of the actual specific surface area of ​​an aggregate to the theoretical specific surface area of ​​the constituent particles of the aggregate in a dispersed state. In the metal oxide precursor, the degree of dispersion K of a single aggregate particle is given by K = S2 / nS1, where S1 is the surface area of ​​a single constituent particle (i.e., a single crystal particle) in the aggregate particle, n is the number of constituent particles (i.e., single crystal particles) in the aggregate particle, and S2 is the surface area of ​​the aggregate particle.

[0041] The particle size corresponding to the dispersed particles is D. 50 Expressed as a value, D is the particle size corresponding to the aggregated particles. 90 Expressed as a value, under the condition that the density of the same type of material remains unchanged, materials of the same volume have equal mass, and furthermore, from the volume ratio, n = η × (D 90 ) 3 / (D 50 ) 3 We derive the following, and here, considering that the voids between aggregated particles cause a constant deviation in volume, we set the volume deviation coefficient η = 0.6, D 50 and D 90From this, we derive S1 and S2, and K=D 50 / (η×D 90 Here, the volume deviation coefficient η is calculated based on the fact that the equivalent diameter of aggregated particles is 5-30 times that of single-crystal particles, and the porosity is estimated from two angles in two and three dimensions, so the volume deviation coefficient η takes an average value of 0.6.

[0042] The degree of dispersion K of the metal oxide precursor in the embodiments of this application is 0.467-0.917. When the degree of dispersion K is within the range of 0.467-0.917, the particles are well dispersed and aggregation is minimal. When K > 0.467, it indicates that a significant portion of the particles are dispersed in the system, the K value increases, the proportion of dispersed particles increases, and the proportion of aggregates decreases. In this range, the interaction force between particles decreases, and the particles are more likely to maintain their dispersed state. The higher the degree of dispersion K, the more the particles can expose their surface area, thus increasing the surface area contribution of individual particles. When K is 0.917, most particles are dispersed, the effective surface area involved in the electrochemical reaction increases, and the electrochemical reaction activity of the material is highest. On the other hand, the degree of dispersion K of the metal oxide precursor is 0.467-0.917. At this specific degree of dispersion, aggregation of the metal oxide precursor is effectively reduced, and it can be used directly in the manufacture of cathode materials without the need for processing such as polishing or crushing. Even if some aggregated particles are present, the metal oxide precursor has a certain degree of dispersion, making it easier for the aggregated particles to disperse completely during the manufacturing process of the cathode material. This is advantageous for improving the uniformity effect of the mixed material, resulting in good consistency of the manufactured cathode material, which is advantageous for improving the stability of performance testing of the cathode material, as well as for reducing costs and improving production efficiency. On the other hand, the metal oxide precursor has a relatively high specific surface area, which is advantageous for improving the sintering activity of the metal oxide precursor during the manufacturing process of the cathode material, and reduces production energy consumption.

[0043] In one embodiment, when the cumulative particle size distribution percentage of the metal oxide precursor reaches 50%, the corresponding particle size may be 1.5 μm-4.0 μm, i.e., 1.5 μm ≤ D 50The particle size is ≤4.0 μm. For example, when the cumulative particle size distribution percentage of the metal oxide precursor reaches 50%, the corresponding particle size may be any typical but non-limiting point value or an interval value between any two point values, such as 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, etc. (See above D) 50 In this case, the average particle size of the single crystal grain is D 50 Represented by D 50 The smaller the value, the greater the surface energy of the particles, and the more easily the particles aggregate, reducing the surface energy. Aggregation reduces the specific surface area, and furthermore, D 50 The smaller the value, the worse the variance, meaning K approaches 0. 50 The particle size is preferably between 1.5 μm and 4.0 μm because if the particle size is too small, the surface energy is high and aggregation is likely to occur, and the smaller the crystal grains, the higher the proportion of grain boundaries, which can cause more grain boundary defects and potentially affect structural stability. If the particle size is too large, the diffusion pathway of lithium ions becomes longer, which can further affect the rate of operation of the battery, and if the particles are too large, it may become difficult for the electrochemical reaction to proceed uniformly.

[0044] In one embodiment, the particle size corresponding to the point when the cumulative particle size distribution percentage of the metal oxide precursor reaches 90% may be 4 μm - 10 μm, i.e., 4 μm ≤ D 90 The particle size is ≤10 μm. For example, when the cumulative particle size distribution percentage of the metal oxide precursor reaches 90%, the corresponding particle size may be any typical but non-limiting point value or an interval value between any two point values, such as 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. (See above D) 90 In the case of D 90 D represents the equivalent diameter of the aggregate. 90 A larger value indicates a more severe aggregation phenomenon, a smaller specific surface area, and poorer dispersion. 50 and D 90 There is a correlation between the sizes, D 50 The larger the particle, the greater its relative D 90 It also grew larger, D 90 is D 50A value close to this indicates a lower degree of aggregation, i.e., a higher degree of dispersion. 90 The particle size is preferably 4 μm-10 μm, and D 50 Corresponding to the selected value, D 50 Since it cannot be too small, the lower limit is 4 μm, D 90 If the size is too large, aggregation becomes severe, resulting in uneven particle size and distribution, which affects electrochemical performance.

[0045] The embodiments of this application are of metal oxide precursor D 50 and D 90 By adjusting the degree of dispersion provided by the metal oxide precursor, K=D 50 / (η×D 90 This ensures that the following conditions can be met, which is advantageous for setting the degree of dispersion of the metal oxide precursor to 0.467-0.917. Exemplarily, the degree of dispersion K of the metal oxide precursor may be any typical but non-limiting point value or an interval value between any two point values, such as 0.467, 0.5, 0.6, 0.7, 0.8, 0.9, 0.917.

[0046] In some embodiments, the degree of dispersion K of the metal oxide precursor is 0.5-0.9. In other embodiments, the degree of dispersion K of the metal oxide precursor is 0.6-0.8. In the embodiments of this application, the degree of dispersion K of the metal oxide precursor facilitates the complete dispersion of the metal oxide precursor during the manufacturing process of the cathode material, thereby improving the stability of performance testing of the cathode material, reducing costs, and improving production efficiency.

[0047] In one embodiment, the specific surface area of ​​the metal oxide precursor is 4 m². 2 / g-12m 2 The specific surface area of ​​a metal oxide precursor is 4 m² / g, and as an example, the specific surface area of ​​a metal oxide precursor is 4 m². 2 / g, 5m 2 / g, 6m 2 / g, 7m 2 / g, 8m 2 / g, 9m 2 / g, 10m 2 / g, 11m 2 / g, 12m2 It may be a typical and non-limiting arbitrary point value such as / g or an interval value between any two point values. In the embodiments of this application, since the degree of dispersion K of the metal oxide precursor is 0.467-0.917, the metal oxide precursor has a high specific surface area, and the relationship between the degree of dispersion value K and the specific surface area S is,

number

[0048] In one embodiment, the loose bulk density of the metal oxide precursor is 0.4 g / cm³. 3 -1.2g / cm 3 For example, the loose bulk density of the metal oxide precursor is 0.4 g / cm³. 3 , 0.5 g / cm 3 , 0.6 g / cm³ 3 , 0.7 g / cm³ 3 , 0.8 g / cm³ 3 , 0.9 g / cm³ 3 1.0 g / cm³ 3 , 1.1 g / cm³ 3 , 1.2 g / cm³ 3It can be any typical but non-limiting point value or an interval value between any two point values. In the embodiments of the present application, since the degree of dispersion K of the metal oxide precursor is 0.467 - 0.917, the metal oxide precursor has a high loose bulk density. If the degree of dispersion is too low, the particles will aggregate severely and irregularly, affecting the deposition behavior of the particles. Although the inside of the aggregates is dense, the gaps between the aggregates are large, resulting in a low loose bulk density. If the degree of dispersion is too high, there will be more voids between the dispersed particles, reducing the adhesion of the overall deposition. The degree of dispersion K in the present application is 0.467 - 0.917, and at the same time, it contains a small amount of aggregates and dispersed particles. The filling of small particles into large voids is beneficial to the improvement of the loose bulk density. In this interval, the loose bulk density first increases and then decreases as K increases.

[0049] In one embodiment, the tap density of the metal oxide precursor is 1.0 g / cm 3 - 2.5 g / cm 3 . Exemplarily, the tap density of the metal oxide precursor can be any typical but non-limiting point value or an interval value between any two point values, such as 1.0 g / cm 3 , 1.2 g / cm 3 , 1.4 g / cm 3 , 1.5 g / cm 3 , 1.6 g / cm 3 , 1.8 g / cm 3 , 2.0 g / cm 3 , 2.2 g / cm 3 , 2.4 g / cm 3 , 2.5 g / cm 3 . In the embodiments of the present invention, since the degree of dispersion K of the metal oxide precursor is 0.467 - 0.917, the metal oxide precursor has a relatively high tap density, which is consistent with the relationship between the above K and the loose bulk density. In the interval where the degree of dispersion K is 0.467 - 0.917, the tap density first increases and then decreases as K increases.

[0050] The embodiments of the present application provide that the degree of dispersion K = D provided by the metal oxide precursor 50 / (η×D 90Based on satisfying the following conditions, it has a good degree of dispersion, contains aggregated and dispersed particles, contributes to filling voids, and further improves tap density and loose bulk density. In the process of manufacturing cathode materials, metal oxide precursors can be dispersed more easily, which is advantageous for the uniformity of cathode coating, improves the stability of performance tests of cathode materials, and is advantageous for cost reduction and improved production efficiency.

[0051] In one embodiment, the equivalent diameter of the aggregate particles is 5 to 30 times the particle size of the single crystal particles. Exemplarily, the equivalent diameter of the aggregate particles is a typical but non-limiting arbitrary point value or an interval value between any two point values, such as 5, 6, 8, 10, 15, 20, 25, or 30 times the particle size of the single crystal particles. In this case, if the aggregates are too large, the electrochemical reaction becomes non-uniform, the diffusion pathway of lithium ions lengthens, and the rate properties are affected. If the degree of particle dispersion is too high, it is unfavorable for improving loose bulk density and tap density, leading to a decrease in battery capacity and energy density.

[0052] The embodiments of this application demonstrate the degree of dispersion K=D provided by the metal oxide precursor. 50 / (η×D 90 By adjusting the aggregation size of single crystal particles in the aggregate based on the requirement of satisfying the following conditions, D90 can be brought closer to D50, which is advantageous for the uniformity of cathode coating and allows the metal oxide precursor to be used directly in the manufacture of cathode material without the need for processing such as polishing or crushing.

[0053] In one embodiment, the general chemical formula of the metal oxide precursor is Mn a M 1-a It is represented as O2, where 0.1 ≤ a ≤ 0.9, and M is at least one selected from Ni, Fe, Cu, Zn, Co, Mg, Al, and Ti. The metal oxide precursor in the examples of this application may be a binary metal oxide, a ternary metal oxide, or a quaternary metal oxide, and it should be understood that the examples of this application are not limited thereto.

[0054] In one embodiment, having a metal content of 70% or more in the metal oxide precursor not only increases the volume and reduces transportation costs, but also, when used in the manufacture of cathode materials for sodium-ion batteries, increases the amount that can be packed into a sagger, which is advantageous in further improving productivity and reducing energy consumption. Exemplarily, the metal content of the metal oxide precursor may be any typical but non-limiting point value or an interval value between any two point values, such as 70%, 75%, 80%, 85%, 90%, or 95%.

[0055] The embodiments of this application provide a method for producing the above-mentioned metal oxide precursor, wherein the production method is selected from spray pyrolysis methods.

[0056] The metal oxide precursors in the embodiments of this application can be produced by spray pyrolysis, and the dispersion degree K of the produced metal oxide precursors is 0.467-0.917, effectively reducing the aggregation phenomenon of the metal oxide precursors, and allowing them to be used directly in the production of cathode materials without the need for processing such as polishing or crushing. At the same time, the metal oxide precursors have a relatively high specific surface area, which is advantageous for improving the sintering activity of the metal oxide precursors in the production process of cathode materials, and reduces production energy consumption.

[0057] Regarding the specific operation of the spray pyrolysis method, conventional methods can be referred to, and a detailed explanation of this is omitted in the embodiments of this application.

[0058] In one embodiment, the pyrolysis temperature of the spray pyrolysis method is 500°C-1000°C, and exemplary, the pyrolysis temperature of the spray pyrolysis method may be any typical but non-limiting point value or an interval value between any two point values, such as 500°C, 600°C, 700°C, 800°C, and 900°C. Under these pyrolysis temperature conditions, if the pyrolysis temperature is low, the degree of crystallinity of the particles is poor, the particle formation process is non-uniform, the particle size is small, the morphology is irregular, aggregation is likely to occur, and dispersibility is poor. If the pyrolysis temperature is high, the degree of crystallinity of the particles is better, the particle size is larger, the morphology is more regular, the distribution is more uniform, and dispersibility is better.

[0059] In one embodiment, the frequency of the supply device of the spray pyrolysis method is 25 Hz - 45 Hz, and it may also be 35 Hz - 40 Hz. Exemplarily, the frequency of the supply device of the spray pyrolysis method is any typical but non-limiting point value such as 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, or an interval value between any two point values. Under the condition of this supply frequency, when the supply frequency is low, the droplets are sufficiently pyrolyzed, the particle size is uniform, the dispersibility is good, and the aggregation phenomenon between particles can be reduced. When the supply frequency is high, the heating of the droplets is non-uniform, the particle dispersibility is poor, it is easy to form a non-uniform particle distribution, the aggregation phenomenon is likely to occur, and the dispersibility is poor.

[0060] In one embodiment, the flow rate of the supply device in the spray pyrolysis method is 0.3 m 3 / h - 0.7 m 3 / h, and it may also be 0.35 m 3 / h - 0.55 m 3 / h. Exemplarily, the flow rate of the supply device in the spray pyrolysis method is any typical but non-limiting point value such as 0.3 m 3 / h, 0.4 m 3 / h, 0.5 m 3 / h, 0.6 m 3 / h, 0.7 m 3 / h, or an interval value between any two point values. Under the condition of the flow rate of this supply device, when the supply flow rate is low, the number of atomized droplets is small, the pyrolysis is more sufficient, the particle size is uniform, the morphology is regular, the aggregation phenomenon is less, and the degree of dispersion is better. When the supply flow rate is high, the number of atomized droplets is large, the particle growth is likely to be insufficient, the particles become non-uniform, the aggregation phenomenon increases, and the degree of dispersion is poor.

[0061] By adjusting conditions such as the pyrolysis temperature, supply frequency, and supply flow rate, it is advantageous to improve the degree of dispersion of the produced metal oxide precursor and effectively improve the aggregation phenomenon.

[0062] The pyrolysis temperature is the operating temperature of the pyrolysis apparatus. If the supply frequency of 50 Hz is equivalent to 100%, then when the supply frequency is 25 Hz-45 Hz, 50%-90% of 50 Hz is used, and when the supply frequency is 35 Hz-40 Hz, 70%-80% of 50 Hz is used. The manufacturing method can satisfy the above conditions of pyrolysis temperature, supply frequency, and supply flow rate. Other manufacturing methods that do not satisfy the above conditions of pyrolysis temperature, supply frequency, and supply flow rate may still allow the metal oxide precursor to satisfy the specific degree of dispersion in the examples of this application under certain conditions, and the examples of this application are not limited to these.

[0063] The embodiments of this application further provide a cathode material manufactured from the above-mentioned metal oxide precursor.

[0064] By using the metal oxide precursor of the embodiment of this application in the manufacture of the cathode material, a single-crystal cathode material with excellent uniformity can be obtained more easily, which is advantageous for improving the discharge capacity and cycle performance of the cathode material.

[0065] The method for manufacturing the positive electrode material will be described by referring to conventional methods, and a detailed explanation thereof will be omitted in the embodiments of this application.

[0066] The embodiment of the present application further provides a positive electrode sheet including a positive electrode current collector and a positive electrode material layer provided on the surface of the positive electrode current collector, wherein the positive electrode material layer includes the above-mentioned positive electrode material.

[0067] The positive electrode material layer of the positive electrode sheet in the embodiment of this application includes a positive electrode material that improves the discharge capacity and cycle performance, thereby improving the electrochemical performance of the positive electrode sheet, such as energy density and cycle stability.

[0068] The embodiments of the present invention further provide a secondary battery including the above-described positive electrode sheet.

[0069] The embodiment of this invention can improve the electrochemical performance of a secondary battery, such as cycle stability and cycle life, by applying a positive electrode sheet having characteristics such as high energy density and cycle stability to a secondary battery.

[0070] For example, the secondary battery may be a sodium-ion battery.

[0071] In one embodiment, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil, and the composite current collector may be formed by forming a metal material on a polymer material substrate. Here, the metal material includes, but is not limited to, at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The polymer material substrate includes, but is not limited to, at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0072] To make it understandable, the positive electrode material layer further comprises a binder and a conductive agent, where the binder may be any commercially available binder used for positive electrode sheets, and includes, but is not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternpolymer, vinylidene fluoride-fluoropropylene-tetrafluoroethylene ternpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic acid ester resin, and may include at least one of these, or a binder manufactured by any known method, and is not limited to these in the embodiments of this application. The conductive agent may be any commercially available conductive agent used in sodium-ion batteries, such as carbon black or graphite.

[0073] The metal oxide precursors, their manufacturing methods, and applications will be further explained below with reference to specific examples. However, as can be understood by those skilled in the art, the following examples are merely for illustrating examples of the present invention and do not limit the scope of the examples of the present invention. Unless specific conditions are stated in the examples, the procedures were carried out under normal conditions or conditions suggested by the manufacturer. Unless the manufacturer is specified for the reagents or equipment used, they are all commonly available products. Example 1

[0074] A mixed metal salt solution was prepared by combining nickel salt, iron salt, and manganese salt in a ratio of 1:1:1 for the molar ratio of metal atoms, and then 0.5 m 3 Under conditions of a liquid supply flow rate of 1 / h and a supply frequency of 37.5 Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets. Under conditions of a thermal decomposition temperature of 750°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as NFM111.

[0075] The surface morphology of the metal oxide precursor produced in this embodiment is shown in Figure 1. The metal oxide precursor contains single crystal particles and local aggregates formed by the irregular aggregation of some single crystal particles, and it can be seen that the equivalent diameter of the aggregates is approximately 17 to 24 times the particle size of the single crystal particles.

[0076] Detection revealed the D of the metal oxide precursor. 50 It is 2.58 μm, D 90 The thickness is 5.98 μm, and the loose bulk density (AD) is 0.67 g / cm³. 3 The tap density (TD) is 1.52 g / cm³. 3 Therefore, the specific surface area (BET) is 4.43 m². 2 It is / g.

[0077] Simulation calculations show that the metal oxide precursor produced in this embodiment satisfies the requirement of a dispersion degree K of 0.719. Example 2

[0078] A mixed metal salt solution was prepared by combining iron salt and manganese salt in a ratio of 4:6 for the molar ratio of metal atoms, and then 0.6m 3 Under conditions of a liquid supply flow rate of 1 / h and a supply frequency of 33.5 Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets, and under conditions of a thermal decomposition temperature of 860°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as FM46.

[0079] The surface morphology of the metal oxide precursor produced in this embodiment is shown in Figure 2. The metal oxide precursor contains single crystal particles and local aggregates formed by the irregular aggregation of some single crystal particles, and it can be seen that the equivalent diameter of the aggregates is approximately 12 to 18 times the particle size of the single crystal particles.

[0080] Detection revealed the D of the metal oxide precursor. 50 It is 1.98 μm, D 90 The thickness is 4.25 μm, and the loose bulk density (AD) is 0.74 g / cm³. 3 The tap density (TD) is 1.84 g / cm³. 3 Therefore, the specific surface area (BET) is 6.87 m². 2 It is / g.

[0081] Simulation calculations show that the degree of dispersion K of the metal oxide precursor produced in this embodiment is 0.776. Example 3

[0082] Nickel salt, copper salt, iron salt, and manganese salt were prepared as a mixed metal salt solution in a ratio of 2:1:3:3 for the molar ratio of metal atoms, and then 0.3m 3 Under conditions of a liquid supply flow rate of 1 / h and a supply frequency of 25Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets. Under conditions of a thermal decomposition temperature of 1000°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as NCFM2133.

[0083] As can be seen from the SEM test, the metal oxide precursor contains single crystal particles and local aggregates formed by the irregular aggregation of some single crystal particles, and the equivalent diameter of the aggregates is approximately 15 to 20 times the particle size of the single crystal particles.

[0084] Detection revealed the D of the metal oxide precursor. 50 It is 3.84 μm, D 90 The thickness is 8.67 μm, and the loose bulk density (AD) is 0.82 g / cm³. 3 The tap density (TD) is 1.93 g / cm³. 3 Therefore, the specific surface area (BET) is 9.69 m². 2 It is / g.

[0085] Simulation calculations show that the degree of dispersion K of the metal oxide precursor produced in this embodiment is 0.738. Example 4

[0086] A mixed metal salt solution was prepared by combining copper salt, iron salt, and manganese salt in a metal atom molar ratio of 4:2:4, and then 0.7m 3 Under conditions of a liquid supply flow rate of 1 / h and a supply frequency of 45 Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets. Under conditions of a thermal decomposition temperature of 520°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as CFM424.

[0087] As can be seen from the SEM test, the metal oxide precursor contains single crystal particles and local aggregates formed by the irregular aggregation of some single crystal particles, with the equivalent diameter of the aggregates being approximately 24 to 30 times the particle size of the single crystal particles.

[0088] Detection revealed the D of the metal oxide precursor. 50 It is 1.56 μm, D 90 The thickness is 4.21 μm, and the loose bulk density (AD) is 0.46 g / cm³. 3 The tap density (TD) is 1.08 g / cm³. 3 Therefore, the specific surface area (BET) is 4.39 m². 2 It is / g.

[0089] Simulation calculations show that the degree of dispersion K of the metal oxide precursor produced in this embodiment is 0.618. Example 5

[0090] A mixed metal salt solution was prepared by combining nickel salt, cobalt salt, and manganese salt in a ratio of 6:1:3 for the molar ratio of metal atoms, and then 0.7m 3 Under conditions of a liquid supply flow rate of 1 / h and a supply frequency of 40 Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets. Under conditions of a thermal decomposition temperature of 610°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as NCM613.

[0091] As can be seen from the SEM test, the metal oxide precursor contains single crystal particles and local aggregates formed by the irregular aggregation of some single crystal particles, with the equivalent diameter of the aggregates being approximately 22 to 30 times the particle size of the single crystal particles.

[0092] Detection revealed the D of the metal oxide precursor. 50 It is 2.15 μm, D 90 The thickness is 7.64 μm, and the loose bulk density (AD) is 0.47 g / cm³. 3 The tap density (TD) is 1.23 g / cm³. 3 Therefore, the specific surface area (BET) is 4.98 m². 2 It is / g.

[0093] Simulation calculations show that the degree of dispersion K of the metal oxide precursor produced in this embodiment is 0.915. Example 6

[0094] A mixed metal salt solution was prepared by combining nickel salt, cobalt salt, and manganese salt in a ratio of 6:1:3 for the molar ratio of metal atoms. Then, 0.3m 3Under conditions of a liquid supply flow rate of 1 / h and a supply frequency of 25 Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets. Under conditions of a thermal decomposition temperature of 920°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as NCM613.

[0095] As can be seen from the SEM test, the metal oxide precursor contains single crystal particles and local aggregates formed by the irregular aggregation of some single crystal particles, and the equivalent diameter of the aggregates is approximately 5 to 12 times the particle size of the single crystal particles.

[0096] Detection revealed the D of the metal oxide precursor. 50 It is 3.98 μm, D 90 The thickness is 7.25 μm, and the loose bulk density (AD) is 0.46 g / cm³. 3 The tap density (TD) is 1.13 g / cm³. 3 The specific surface area (BET) is 11.3 m². 2 It is / g.

[0097] Simulation calculations show that the degree of dispersion K of the metal oxide precursor produced in this embodiment is 0.469. Comparative Example 1

[0098] A mixed metal salt solution was prepared by combining nickel salt, iron salt, and manganese salt in a ratio of 1:1:1 for the molar ratio of metal atoms, and then 0.75m 3 Under conditions of a liquid supply flow rate of / h and a supply frequency of 35Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets. Under conditions of a thermal decomposition temperature of 1050°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as NFM111.

[0099] As shown in Figure 3, the surface morphology of the metal oxide precursor produced in this embodiment shows that the aggregation phenomenon of the metal oxide precursor is severe, and the equivalent diameter of the aggregates is approximately 28 to 45 times the particle size of the single crystal particles.

[0100] Detection revealed the D of the metal oxide precursor. 50 It is 4.6 μm, D 90 The thickness is 17.32 μm, and the loose bulk density (AD) is 0.35 g / cm³. 3 The tap density (TD) is 0.94 g / cm³. 3 Therefore, the specific surface area (BET) is 2.98 m². 2 It is / g.

[0101] Simulation calculations show that the degree of dispersion K of the metal oxide precursor produced in this embodiment is only 0.443. Comparative Example 2

[0102] Nickel salt, copper salt, iron salt, and manganese salt were prepared as a mixed metal salt solution in a metal atom molar ratio of 2:1:3:3, and then 0.28m 3 Under conditions of a liquid supply flow rate of 1 / h and a supply frequency of 23.5 Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets. Under conditions of a thermal decomposition temperature of 480°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as CFM2133.

[0103] As shown in Figure 4, the surface morphology of the metal oxide precursor produced in this embodiment shows that the aggregation phenomenon of the metal oxide precursor is severe, and the equivalent diameter of the aggregates is approximately 35 to 50 times the particle size of the single crystal particles.

[0104] Detection revealed the D of the metal oxide precursor. 50 It is 0.85 μm, D 90 The thickness is 3.15 μm, and the loose bulk density (AD) is 0.36 g / cm³. 3 The tap density (TD) is 0.97 g / cm³. 3 Therefore, the specific surface area (BET) is 3.38 m². 2 It is / g.

[0105] Simulation calculations show that the degree of dispersion K of the metal oxide precursor produced in this embodiment is only 0.45. Comparative Example 3

[0106] A mixed metal salt solution was prepared by combining nickel salt, iron salt, and manganese salt in a ratio of 1:1:1 for the molar ratio of metal atoms, and then 0.75m 3 Under conditions of a liquid supply flow rate of / h and a supply frequency of 40Hz, a mixed metal salt solution is placed in a calcination furnace in the form of atomized droplets. Under conditions of a thermal decomposition temperature of 450°C, the atomized droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as NFM111.

[0107] As can be seen from the SEM test, the metal oxide precursor contains single crystal particles and local aggregates formed by the irregular aggregation of some single crystal particles, and the equivalent diameter of the aggregates is approximately 5 to 10 times the particle size of the single crystal particles.

[0108] Detection revealed the D of the metal oxide precursor. 50 It is 1.8 μm, D 90 The thickness is 3.16 μm, and the loose bulk density (AD) is 0.41 g / cm³. 3 The tap density (TD) is 0.95 g / cm³. 3 Therefore, the specific surface area (BET) is 6.9 m². 2 It is / g.

[0109] Simulation calculations show that the degree of dispersion K of the metal oxide precursor produced in this embodiment is 0.95. Application examples

[0110] The metal oxide precursors produced in Examples 1-6 and Comparative Examples 1 and 3 were mixed with sodium carbonate in a molar ratio of 1:1. The mixture was then placed in a muffle furnace and heated to 900°C at a heating rate of 5°C / min under an air atmosphere. After constant temperature sintering for 15 hours, the mixture was allowed to cool naturally, then pulverized and sieved to obtain the cathode material.

[0111] The manufactured positive electrode material was used to create a sodium-ion coin cell, and the capacity retention rate after 50 cycles under voltage conditions of 2V-4.15V was measured. The measurement results are shown in Table 1. [Table 1]

[0112] As can be seen from Table 1, the metal oxide precursors produced in Examples 1-6 were used as positive electrode materials for sodium-ion batteries, and the sodium-ion batteries could achieve a capacity retention rate of 90% or more after 50 cycles under voltage conditions of 2V-4.15V. Compared with Examples 1-6, Comparative Example 1 had excessively high liquid supply flow rate and thermal decomposition temperature, resulting in strong thermal motion of particles and increased collisions between particles, leading to severe aggregation of precursor particles and a dispersion degree of less than 0.467, resulting in poor performance stability. Comparative Example 2 had low liquid supply flow rate and thermal decomposition temperature, causing the wet particles to stick together in the initial stage, forming larger particles, and aggregation also occurred due to electrostatic forces, van der Waals forces, etc. between particles, resulting in a dispersion degree of less than 0.467, resulting in performance stability of only about 72%. In Comparative Example 3, the K value exceeded 0.917 and reached 0.95, the dispersion degree also decreased, and the cycle stability was poor.

[0113] The foregoing describes only preferred embodiments of the present application and does not limit it. Those skilled in the art will be able to modify and change the present application in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of this application.

Claims

1. A metal oxide precursor, The metal oxide precursor comprises dispersed single-crystal particles and aggregate particles that are partly composed of single-crystal particles. The degree of dispersion K of the metal oxide precursor is 0.467-0.917, and K=D 50 / (η×D 90 ) and here, D 50 This is the particle size that corresponds to the point when the cumulative particle size distribution percentage of the metal oxide precursor reaches 50%, and D 90 η is the particle size corresponding to the point when the cumulative particle size distribution percentage of the metal oxide precursor reaches 90%, and η is the volume deviation coefficient, where η = 0.

6. A metal oxide precursor characterized by the following features.

2. 1.5 μm ≤ D 50 The metal oxide precursor according to claim 1, characterized in that it is ≤4.0 μm.

3. 4μm≦D 90 The metal oxide precursor according to claim 1, characterized in that it is ≤10 μm.

4. The metal oxide precursor according to any one of claims 1 to 3, characterized in that the degree of dispersion K of the metal oxide precursor is 0.5 to 0.

9.

5. The metal oxide precursor according to claim 4, characterized in that the degree of dispersion K of the metal oxide precursor is 0.6-0.

8.

6. The specific surface area of ​​the metal oxide precursor is 4 m² 2 / g-12m 2 The metal oxide precursor according to claim 1, characterized in that it is / g.

7. The bulk density of the metal oxide precursor is 0.4 g / cm 3 -1.2 g / cm 3 The metal oxide precursor according to claim 1, characterized in that it is as described above.

8. The tap density of the metal oxide precursor is 1.0 g / cm³. 3 -2.5g / cm 3 The metal oxide precursor according to claim 1, characterized in that it is the same as described in claim 1.

9. The metal oxide precursor according to claim 1, characterized in that the equivalent diameter of the aggregate particles is 5 to 30 times the particle size of the single crystal particles.

10. In the metal oxide precursor, the degree of dispersion of a single aggregate particle K = S 2 / nS 1 And here, S 1 is the surface area of ​​a single single crystal particle in the aggregate particle, n is the number of single crystal particles in the aggregate particle, and S 2 is the surface area of ​​the aggregate particles. The metal oxide precursor according to feature 1.

11. The general chemical formula for the aforementioned metal oxide precursor is Mn a M 1-a O 2 The metal oxide precursor according to claim 1, characterized in that it is expressed as follows, where 0.1 ≤ a ≤ 0.9, and M is at least one selected from Ni, Fe, Cu, Zn, Co, Mg, Al, and Ti.

12. The metal oxide precursor according to claim 1, characterized in that the metal content of the metal oxide precursor is 70% or more.

13. A method for producing a metal oxide precursor according to any one of claims 1 to 12, selected from a spray pyrolysis method.

14. The method for producing a metal oxide precursor according to claim 13, characterized in that the thermal decomposition temperature of the spray pyrolysis method is 500°C to 1000°C.

15. The method for producing a metal oxide precursor according to claim 13, characterized in that the frequency of the supply device for the spray pyrolysis method is 25 Hz to 45 Hz.

16. The flow rate of the supply device for the spray pyrolysis method is 0.3 m³. 3 / h-0.7m 3 A method for producing a metal oxide precursor according to claim 13, characterized in that the value is / h.

17. A cathode material produced from a metal oxide precursor according to any one of claims 1 to 12 or a metal oxide precursor produced by the method described in any one of claims 13 to 16.

18. A positive electrode sheet comprising a positive electrode current collector and a positive electrode material layer provided on the surface of the positive electrode current collector, wherein the positive electrode material layer comprises the positive electrode material described in claim 17.

19. A secondary battery characterized by including the positive electrode sheet described in claim 18.

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