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 has a single-crystal structure, and the particle size distribution curve function f(x) of the metal oxide precursor represents the volume fraction corresponding to the x particle size, where 0.214 μm ≤ a ≤ 0.260 μm, 1.78 μm ≤ b ≤ 3.1 μm, 8.2 μm ≤ c ≤ 31.2 μm, and ε, μ1, and μ2 are all error coefficients, where -1.5 ≤ ε ≤ 1.5, -0.35 ≤ μ1 ≤ 0.35, and -3 ≤ μ2 ≤ 10. The metal oxide precursor described in the examples of this application has a particle size of 1.2 g / cm³. 3 -3.5g / cm 3 It has a high tap density, which is advantageous for improving the filling rate and compaction density of the positive electrode material, and further improves the volumetric capacity of the battery.

Description

Cross-reference to related applications

[0001] This application claims the priority of a Chinese patent application with the application number 2,023,118,679,548 and the invention title "Metal Oxide Precursor and Its Manufacturing Method and Application", which was filed with the China National Intellectual Property Administration on December 29, 2023, and all of its contents are incorporated herein by reference.

Technical Field

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

Background Art

[0003] [[ID=!7]] The descriptions herein only provide background information related to this application and do not necessarily constitute prior art. Metal oxide precursors produced by conventional spray pyrolysis have relatively uniform particle sizes, relatively small sizes, relatively serious aggregation phenomena, relatively low tap densities of the metal oxide precursors. When used to manufacture cathode materials, they not only cause problems such as relatively small filling amounts in crucibles and too high energy consumption, but also have relatively low volume specific capacities of the cathode materials. In addition, under different manufacturing conditions, the particle size distribution curves of metal oxide precursors with different elements and ratios have inconsistencies and no significant regularity, making it difficult to improve the tap density of the metal oxide precursors.

Summary of the Invention

[0004] One of the objectives of the embodiments of this application is to provide a metal oxide precursor and its manufacturing method and application to solve the problem of the low tap density of the metal oxide precursor.

[0005] The technical solutions adopted in the embodiments of this application are as follows.

[0006] In a first aspect, a metal oxide precursor is provided. The metal oxide precursor has a single crystal structure. The particle size distribution curve function f(x) of the metal oxide precursor represents the volume fraction corresponding to the particle size x and satisfies the following conditions. (1) When a ≤ x ≤ b,

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[0007] In some embodiments, the particle size distribution function f(x) of the metal oxide precursor exhibits a unimodal normal particle size distribution curve.

[0008] In some embodiments, the peak value of the particle size distribution curve function f(x) of the metal oxide precursor is f(x) max The answer is 5-10.

[0009] In some embodiments, the full width at half maximum of the particle size distribution curve function f(x) of the metal oxide precursor is 3 μm to 5 μm.

[0010] In some embodiments, the cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D n n%=Σf(x), and the particle size distribution curve function is D 25 In this case, 0.5 μm ≤ x ≤ 2.0 μm.

[0011] In some embodiments, the cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D n n%=Σf(x), and the cumulative particle size distribution curve function is D 50 In this case, 1.2 μm ≤ x ≤ 3.8 μm.

[0012] In some embodiments, the cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D n where n% = Σf(x), and when the cumulative particle size distribution curve function is D 75 it is 2 μm ≤ x ≤ 5 μm.

[0013] In some embodiments, in the particle size distribution curve function f(x) of the metal oxide precursor, the particle size distribution span value is 1.0 - 2.5.

[0014] In some embodiments, the chemical formula of the metal oxide precursor is Mn y M 1-y O2, where 0.1 ≤ y ≤ 0.9, and M is at least one selected from Ni, Fe, Cu, Zn, Co, Ti, Mg, Al.

[0015] In some embodiments, the metal oxide precursor is cubic crystal system.

[0016] In some embodiments, the tap density of the metal oxide precursor is 1.2 g / cm 3 -3.5 g / cm 3 .

[0017] In a second aspect, the present application provides a method for manufacturing the above metal oxide precursor selected from spray pyrolysis method.

[0018] In some embodiments, the pyrolysis temperature of the spray pyrolysis method is 550°C - 950°C.

[0019] In some embodiments, the atomization pressure of the spray pyrolysis method is 0.35 MPa - 0.7 MPa.

[0020] In some embodiments, the liquid supply flow rate obtained by the spray pyrolysis method is 0.3 m 3 / h - 0.8 m 3 / 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 application 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, wherein the positive electrode material layer comprises the positive electrode material described above.

[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 this application are that, when the particle size distribution curve of the metal oxide precursor satisfies a specific functional relationship, it has a unimodal normal state particle size distribution curve and a wide particle size distribution, while the metal oxide precursor has a high tap density, which is advantageous when used in the manufacture of cathode materials, as it improves the saggar filling amount and reduces energy consumption. Furthermore, the wide particle size distribution characteristic of the metal oxide precursor is easily inherited by the cathode material, allowing the cathode material to have a high packing rate and compaction density, which is advantageous in improving the volume-specific capacity of the battery. On the other hand, metal oxide precursors that satisfy the specific particle size distribution curve functional relationship according to this application can be widely applied to different elements, proportions, and manufacturing conditions, and all can achieve a high tap density effect.

[0025] The beneficial effect of the method for producing a metal oxide precursor according to the embodiment of the present application is that the metal oxide precursor can be produced by spray pyrolysis, the produced metal oxide precursor has a single crystal structure, and the particle size distribution of the single crystal structure in the precursor satisfies the particle size distribution curve function f(x), which is advantageous for improving the high tap density of the metal oxide precursor, and can be widely applied to different elements, proportions, and production conditions.

[0026] The beneficial effect of the cathode material according to the embodiment of the present application is that by using the metal oxide precursor of the embodiment of the present application in the manufacture of the cathode material, the cathode material inherits the broad particle size distribution characteristics of the metal oxide precursor, achieves high packing efficiency and compaction density, and improves the volumetric specific capacity of batteries such as sodium ions.

[0027] The beneficial effect of the positive electrode sheet according to the embodiment of the present invention is that, because the positive electrode material layer of the positive electrode sheet contains a positive electrode material having the high packing density and compaction density described above, it improves the electrochemical performance of the positive electrode sheet, such as energy density and cycle stability.

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

[0029] To more clearly explain the technical concepts in the embodiments of this application, the following drawings, which may be used to describe the embodiments or exemplary technologies, are briefly introduced below. 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 particle size distribution curve diagram of a metal oxide precursor in an embodiment of the present invention.

[0031] Figure 2 is a scanning electron microscope image of the metal oxide precursor produced in Example 1.

[0032] Figure 3 shows the particle size distribution curve of the metal oxide precursor produced in Example 1.

[0033] Figure 4 is a scanning electron microscope image of the metal oxide precursor produced in Example 2.

[0034] Figure 5 shows the particle size distribution curve of the metal oxide precursor produced in Example 2.

[0035] Figure 6 shows the particle size distribution curve of the metal oxide precursor produced in Example 3.

[0036] Figure 7 is a scanning electron microscope image of the metal oxide precursor produced in Comparative Example 1.

[0037] Figure 8 shows the particle size distribution curve of the metal oxide precursor produced in Comparative Example 1.

[0038] Figure 9 shows the particle size distribution curve of the metal oxide precursor produced in Comparative Example 2.

[0039] Figure 10 shows the charge-discharge performance test curves of the positive electrode materials manufactured in Examples 1-3 and Comparative Examples 1 and 2, where A is the charge-discharge performance curve of the positive electrode material manufactured in Example 1, B is the charge-discharge performance curve of the positive electrode material manufactured in Example 2, C is the charge-discharge performance curve of the positive electrode material manufactured in Example 3, D is the charge-discharge performance curve of the positive electrode material manufactured in Comparative Example 1, and E is the charge-discharge performance curve of the positive electrode material manufactured in Comparative Example 2. [Modes for carrying out the invention]

[0040] To further clarify the purpose, technical proposal, 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.

[0041] 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.

[0042] 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. In the text, terms used in the description of the embodiments of this application are for the purpose of describing a particular embodiment or example 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, including any combination and all combinations of related column items, which include any two, any more, or all combinations of related column items.

[0043] To illustrate the technical proposal described in this application, a detailed explanation follows with reference to specific drawings and embodiments.

[0044] Some embodiments of the present invention provide a metal oxide precursor having a single-crystal structure, where the particle size distribution curve function f(x) of the metal oxide precursor shows the corresponding volume fraction at particle size x, and satisfies the following conditions:

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[0045] In the particle size distribution curve function f(x) of the metal oxide precursor in the embodiments of this application, the unit of particle size x is μm by default. When calculating f(x), it is not necessary to substitute the μm unit, and only the numerical value of x needs to be substituted. The unit of the corresponding volume fraction f(x) obtained by calculating with an arbitrary x particle size is %. Furthermore, the particle size of the metal oxide precursor refers to the macroscopic form. When detecting the particle size distribution in the usual way, the particle size distribution in the dispersion pool includes the aggregated state. Single-crystal precursors have structural integrity and are easy to sinter as single-crystal cathodes. Single-crystal structures have fewer grain boundaries, which is advantageous for improving electron and ionic conductivity, further improving battery rate characteristics. Also, there are fewer defects due to fewer grain boundaries, resulting in higher strength and stability, reducing the occurrence of side reactions at grain boundaries, and improving the battery cycle life. The chemical composition and structure inside the single-crystal structure are more uniform, contributing to the uniform progress of electrochemical reactions.

[0046] The particle size distribution in the metal oxide precursor of the embodiment of the present application satisfies the above particle size distribution curve function f(x). The relationship between f(x) and the tap density of the precursor indicates that the particle size corresponding to the peak position represents the most common particle size. A wide particle size distribution indicates that the particle sizes have diversity, which is advantageous for filling voids and improving the tap density under vibration conditions. For a ≦ x ≦ b, f(x) shows a particle size distribution smaller than the median diameter. For b < x ≦ c, f(x) shows a particle size distribution larger than the median diameter. For x c, it shows particle sizes outside the f(x) distribution. This function can reflect the particle size distribution characteristics of the product of the present application. The three peak values of x, namely X = a and X = c, represent the minimum and maximum particle size values in the sample respectively, and X = b is the highest point of the particle size distribution curve, indicating that the particles of this particle size account for the largest proportion in the sample. In a symmetric distribution, the peak value is the value corresponding to D 50 and in an asymmetric distribution, D 50The values ​​may vary slightly. When x=b, a large value of b may indicate larger median diameter particles, more depositional voids, and lower tap density. Conversely, a small peak particle size may indicate finer particles, tighter deposition, and higher tap density. For X=a and X=c, a larger difference between the maximum and minimum particle sizes indicates greater particle diversity. Larger particles contribute to supporting the depositional structure and prevent excessive compaction, while smaller particles contribute to filling voids and increasing tap density. Here, a represents the minimum particle size; if the minimum particle size value is too small, inter-particle adhesion increases, potentially affecting fluidity and processing performance. If the minimum particle size is appropriately small, it contributes to filling voids and increases tap density. b represents the maximum particle size; a large maximum particle size increases deposited voids, decreases tap density, and may affect reaction uniformity, but appropriately large particles can contribute to supporting the depositional structure and prevent excessive compaction. c represents the peak particle size. If the median diameter value is too large, the tap density decreases, affecting the energy density of the battery and reducing conductivity. If the median diameter value is too small, aggregation is more likely during processing, affecting the uniformity of the slurry and the coating process. A moderate median diameter value is preferable because it allows for a balance between tap density, conductivity, and cycle stability.

[0047] In some embodiments, the particle size distribution curve function f(x) of the metal oxide precursor exhibits a unimodal normal particle size distribution curve. The particle size distribution curve of the metal oxide precursor in the embodiments of this application, when satisfying a specific functional relationship, has a unimodal normal particle size distribution curve and a broad particle size distribution. On the one hand, this is advantageous for improving the high tap density of the metal oxide precursor. When used in the manufacture of cathode materials, it is advantageous for improving the sagger filling amount and reducing energy consumption. Furthermore, the broad particle size distribution characteristic of the metal oxide precursor is easily inherited by the cathode material, giving the cathode material a high packing rate and compaction density, which is advantageous for improving the volume-specific capacity of the battery. On the other hand, metal oxide precursors that satisfy the specific particle size distribution curve functional relationship in the embodiments of this application can be widely applied to different elements, proportions, and manufacturing conditions, and all can achieve a high tap density effect.

[0048] In some embodiments, the tap density of the metal oxide precursor is 1.2 g / cm³. 3 -3.5g / cm 3 In this case, the metal oxide precursor is 1.2 g / cm³. 3 -3.5g / cm 3 The high tap density of the metal oxide precursor is advantageous when used in the manufacture of cathode materials, as it improves the saggar filling volume and reduces energy consumption. Furthermore, the broad particle size distribution characteristics of the metal oxide precursor are easily inherited by the cathode material, resulting in a cathode material with high packing efficiency and compaction density, which is advantageous for improving the volume-specific capacity of the battery. For example, the high tap density of the metal oxide precursor is 1.2 g / cm³. 3 1.5 g / cm³ 3 1.8 g / cm³ 3 2.0 g / cm³ 3 2.5 g / cm³ 3 , 3g / cm³ 3 3.5 g / cm³ 3 These may be typical but non-restrictive arbitrary point values ​​or interval values ​​between any two point values.

[0049] As shown in Figure 1, this is a particle size distribution curve diagram of a metal oxide precursor in one embodiment, and the highest point of the particle size distribution curve function f(x) of the metal oxide precursor is the peak value f(x). max And f(x) max The value is 5-10. For example, the peak value of the particle size distribution curve function f(x) of a metal oxide precursor is f(x). max f(x) may be any typical but non-restrictive point value such as 5, 6, 7, 8, 9, 10, or an interval value between any two point values. If the peak value is too large, it causes a large amount of voids during the deposition process, affecting the tap density and reducing the energy density. If the peak value is too small, interparticle aggregation progresses, which is unfavorable for producing and coating a uniform slurry. max A value of 5-10 contributes to optimizing tap density and interparticle packing effect, thereby improving energy density and structural stability.

[0050] In some embodiments, the full width at half maximum of the particle size distribution curve function f(x) of the metal oxide precursor is the half-peak value f(x)max When it is / 2, it is the difference between the corresponding particle size x1 and particle size x2 in the particle size distribution curve function f(x), where particle size x1 and particle size x2 are independently selected from any value between 0.6 μm and 6 μm.

[0051] In some examples, the full width at half maximum (FWHM) of the particle size distribution curve function f(x) of the metal oxide precursor is 3 μm–5 μm. Exemplarily, the FWHM of the particle size distribution curve function f(x) of the metal oxide precursor may be any typical but non-restrictive point value such as 3 μm, 4 μm, or 5 μm, or an interval value between any two points. FWHM indicates particle size consistency; a smaller FWHM indicates particle size uniformity, while a larger FWHM indicates particle size diversity. Within a FWHM of 3–5 μm, particle size exhibits a certain diversity, with smaller particles filling voids, achieving high tap density, and further improving battery capacity and energy density.

[0052] In some embodiments, the cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D n Therefore, n% = Σf(x), where f(x) is the percentage of volume occupied by the particle size when the particle size is x μm, and D n n% is the particle size corresponding to the time when x is maximum in the accumulation process, given that the cumulative volume percentage is n%. min This is the total volume fraction when accumulated from ) to f(x). The cumulative particle size distribution curve function is D 25 In this case, 0.5 μm ≤ x ≤ 2.0 μm. Note that particle size distribution is the volume percentage of particles of different particle sizes in a powder sample measured by specific instruments and methods, and D n In this case, n is the percentage. 25 This is the particle size corresponding when the cumulative particle size distribution number of the metal oxide precursor reaches 25%. 25 This indicates that 25% of the particle volume is smaller than this particle size, i.e., it represents the content of smaller particles. 25If the size is too large, it indicates a low proportion of small particles, which can reduce the reaction surface area and potentially decrease the battery's initial discharge capacity. 25 If the value is too small, it indicates a high proportion of small particles, which can increase the reaction surface area and improve the initial volume, but it also increases side reactions and affects the cycle lifetime. 25 The x-value is within the range of 0.5 μm ≤ x ≤ 2.0 μm, which can improve the initial capacity, reduce side reactions, and extend the cycle life.

[0053] In some embodiments, the cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D n Therefore, n%=Σf(x), and the cumulative particle size distribution curve function is D 50 In this case, 1.2 μm ≤ x ≤ 3.8 μm. Note that D 50 This is the particle size corresponding when the cumulative particle size distribution number of the metal oxide precursor reaches 50%. 50 Regarding the median diameter, D 50 If the specific surface area is too large, it can lead to insufficient specific surface area, poor conductivity, low electrode density, and structural stability problems, potentially reducing the overall performance and lifespan of the battery. 50 If the size is too small, it can improve reaction activity and specific surface area, but it can lead to problems such as increased side reactions, particle aggregation, and decreased mechanical strength. 50 The x-value is within the range of 1.2 μm ≤ x ≤ 3.8 μm, ensuring sufficient specific surface area and reaction activity while avoiding excessive side reactions. Simultaneously, it improves tap density and conductivity, thereby enhancing the battery's energy density and rate performance.

[0054] In some embodiments, the cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D n Therefore, n%=Σf(x), and the cumulative particle size distribution curve function is D 75 In this case, 2μm ≤ x ≤ 5μm. Note that D 75 This is the particle size corresponding when the cumulative particle size distribution number of the metal oxide precursor reaches 75%. 75Regarding (the amount of large particles), D 75 The size is too large, the proportion of large particles is high, and the voids are large during deposition, resulting in a low tap density, which affects the energy density. D 75 If the particles are too small, the proportion of larger particles is low, which improves tap density and energy density, but smaller particles are more prone to deformation and stress concentration during volume changes, causing structural deformation or fracture of the material and further affecting structural stability. 75 This falls within the range of 2μm ≤ x ≤ 5μm, which allows for improved energy density while maintaining structural stability.

[0055] In some embodiments, the particle size distribution span value in the particle size distribution curve function f(x) of the metal oxide precursor is 1.0-2.5. Illustratively, the particle size distribution span value in the particle size distribution curve function f(x) of the metal oxide precursor may be any typical but non-restrictive point value or an interval value between any two points, such as 1.0, 1.5, 2.0, 2.5. Note that the particle size distribution span value is K 90 =(D 90 -D 10 ) / D 50 And here, D 10 This is the particle size corresponding when the cumulative particle size distribution number of the metal oxide precursor reaches 10%, and D 90 This is the particle size corresponding when the cumulative particle size distribution number of the metal oxide precursor reaches 90%. 10 If the size is too large, the proportion of very small particles will be relatively low, reducing the surface area and affecting the initial discharge capacity. 10 If the size is too small, the proportion of very small particles will be relatively high, causing aggregation, increasing side reactions, and reducing cycle lifetime. 90 If the value is too large, it can lead to problems such as uneven particle distribution, insufficient specific surface area, low compaction density, poor mechanical performance, and large volume changes, affecting the electrochemical performance and cycle stability of the battery. 90 If the value is too small, it can improve the specific surface area and initial capacity, but it can lead to an increase in side reactions, causing problems such as capacity decay and reduced cycle stability.

[0056] In some embodiments, the chemical formula of the metal oxide precursor is Mn y M 1-y It is represented as O2, where 0.1 ≤ y ≤ 0.9, and M is at least one selected from Ni, Fe, Cu, Zn, Co, Ti, Mg, and Al. 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.

[0057] In some embodiments, the metal oxide precursor is cubic, that is, the single crystal structure of the metal oxide precursor is cubic.

[0058] 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.

[0059] The metal oxide precursors in the embodiments of this application can be produced by spray pyrolysis, and the obtained metal oxide precursors have a single-crystal structure. Furthermore, the particle size distribution of the single-crystal structure in the precursor satisfies the particle size distribution curve function f(x), which is advantageous for improving the high tap density of the metal oxide precursors and can be widely applied to different elements, proportions, and production conditions.

[0060] Regarding the specific operation of the spray pyrolysis method, conventional methods can be referred to, and the embodiments of this application omit such a description.

[0061] In some embodiments, the pyrolysis temperature of the spray pyrolysis method is 550°C-950°C. Under these conditions, if the pyrolysis temperature is too low, the resulting particles may be large and unevenly distributed, potentially leading to low crystallinity. If the pyrolysis temperature is too high, the decomposition rate of the droplets increases, the particle size decreases, and the particle size distribution becomes more uniform. If the pyrolysis temperature is too high, it may lead to particle sintering and aggregation, resulting in larger particle size and a wider particle size distribution.

[0062] Note that the pyrolysis temperature is the operating temperature of the pyrolysis apparatus.

[0063] In some embodiments, the atomization pressure of the spray pyrolysis method is 0.35 MPa-0.7 MPa. Under these pyrolysis temperature conditions, the atomization pressure is high, the atomized droplets are small, and uniform small particles are easily formed during the pyrolysis process. However, if the atomization pressure is too high, some droplets may rapidly agglomerate during spraying, potentially forming a secondary agglomeration phenomenon. With a low atomization pressure, the atomized droplets are large, the size of the generated particles is large, and the particle size distribution is broad. Within the atomization pressure range of the present invention, the particle size is appropriate, the unimodal particle size distribution is broad, which is advantageous for improving tap density, and the agglomeration phenomenon is not evident.

[0064] In some embodiments, the feed flow rate in the spray pyrolysis method is 0.3 m 3 / h-0.8m 3 The rate is / h. Under these thermal decomposition temperature conditions, the liquid flow rate is too high and the atomization capacity of the nozzle is limited, so a large amount of liquid cannot be sufficiently dispersed into small droplets, and some droplets cannot be completely dried, forming large particles or agglomerating, which may result in an overly broad particle size distribution. At a low liquid flow rate, the droplets dry and decompose in sufficient time, forming relatively small and uniform particles. Within the liquid flow rate range of this application, the particle size is appropriate, the unimodal peak of the particle size distribution is broad, which is advantageous for improving tap density, and agglomeration is not evident.

[0065] For example, the pyrolysis temperature in the spray pyrolysis method may be any typical but non-limiting point value or an interval value between any two points, such as 550°C, 600°C, 650°C, 700°C, 800°C, 900°C, and 950°C; the atomization pressure may be any typical but non-limiting point value or an interval value between any two points, such as 0.35 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, and 0.7 MPa; and the feed liquid flow rate may be 0.3 m 3 / h, 0.4m 3 / h, 0.5m 3 / h, 0.6m 3 / h, 0.7m 3 / h, 0.8m 3This may be a typical but non-restrictive arbitrary point value such as / h, or an interval value between any two points.

[0066] By adjusting conditions such as thermal decomposition temperature, atomization pressure, and feed rate, it is advantageous to precisely control metal oxide precursors produced with different elements and proportions, and all of these can satisfy the specific particle size distribution curve function of the embodiment of this application, thereby achieving a high tap density effect.

[0067] While the manufacturing method satisfies the above-mentioned conditions such as thermal decomposition temperature, atomization pressure, and feed rate, other manufacturing methods that do not satisfy these conditions can still produce a specific particle size distribution curve in the metal oxide precursor under certain conditions, and the embodiments of this application are not limited to such methods.

[0068] The embodiments of this application further provide a cathode material manufactured from the above-mentioned metal oxide precursor.

[0069] By using the metal oxide precursor of the embodiment of this application in the manufacture of a cathode material, the cathode material inherits the broad particle size distribution characteristics of the metal oxide precursor, achieving high packing efficiency and compaction density, and improving the volume-specific capacity of batteries such as sodium ions.

[0070] The method for manufacturing the positive electrode material will be described by referring to conventional methods, and this will not be explained in the embodiments of this application.

[0071] Embodiments of the present application further provide 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.

[0072] The positive electrode material layer of the positive electrode sheet in the embodiment of this application contains the positive electrode material having the high packing density and compaction density described above, thereby improving the electrochemical performance of the positive electrode sheet, such as energy density and cycle stability.

[0073] The embodiments of the present invention further provide a secondary battery including the above-described positive electrode sheet.

[0074] 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.

[0075] For example, the secondary battery may be a sodium-ion battery.

[0076] In some embodiments, 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, where 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, and 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).

[0077] 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.

[0078] The following specific examples will further illustrate the metal oxide precursor, its manufacturing method, and applications. However, as can be understood by those skilled in the art, the following examples are merely for explaining the embodiments of the present invention and do not limit the scope of the embodiments of the present invention. For those not specifying specific conditions in the examples, the operations were carried out according to normal conditions or the conditions proposed by the manufacturer. For reagents or equipment not specifying the manufacturer, all are ordinary products available commercially.

[0079] Example 1 Nickel salt, iron salt, and manganese salt were prepared into a mixed metal salt solution at a ratio where the molar ratio of metal atoms was 1:1:1. Next, under the conditions of a liquid supply flow rate of 0.38 m 3 / h and an atomization pressure of 0.35 MPa, the mixed metal salt solution was put into a firing furnace in the form of droplets. Under the condition of a thermal decomposition temperature of 550 °C, the droplets underwent processes such as evaporation, drying, thermal decomposition, and sintering to form a metal oxide precursor. The general formula of the manufactured metal oxide precursor product is represented as NFM111.

[0080] The surface morphology of the metal oxide precursor manufactured in this example is as shown in Figure 2. It can be seen that the metal oxide precursor has a single crystal structure, and the particle size distribution is wide, and the aggregation phenomenon is significantly improved.

[0081] The particle size distribution curve of the metal oxide precursor manufactured in this example is as shown in Figure 3. The particle size distribution curve of the metal oxide precursor is a normal curve with a single peak width distribution, and the particle size distribution curve function f(x) is such that when 0.243 ≤ x ≤ 2.421,

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Number

[0082] Example 2 Nickel salt, copper salt, iron salt, and manganese salt were prepared in a mixed metal salt solution at a molar ratio of metal atoms of 2:1:3:3. Next, at a liquid supply flow rate of 0.55 m 3 / h and an atomization pressure of 0.7 MPa, the mixed metal salt solution was put into a firing furnace in the form of droplets. Under the condition of a thermal decomposition temperature of 950 °C, the droplets underwent processes such as evaporation, drying, thermal decomposition, and sintering molding to form a metal oxide precursor. The general formula of the manufactured metal oxide precursor product is represented as NCFM2133.

[0083] The surface morphology of the metal oxide precursor manufactured in this example is as shown in Fig. 4. It can be seen that the metal oxide precursor has a single crystal structure, and the particle size distribution is wide, and the aggregation phenomenon is significantly improved.

[0084] The particle size distribution curve of the metal oxide precursor manufactured in this example is as shown in Fig. 5. The particle size distribution curve of the metal oxide precursor is a normal curve with a single peak width distribution. And the particle size distribution curve function f(x) is such that when 0.214 ≤ x ≤ 1.73,

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[0085] Example 3 Iron salt and manganese salt were prepared in a mixed metal salt solution at a molar ratio of metal atoms of 65:35. Next, at a liquid supply flow rate of 0.80 m 3 / h and an atomization pressure of 0.5 MPa, the mixed metal salt solution was put into a firing furnace in the form of droplets. Under the condition of a thermal decomposition temperature of 720 °C, the droplets underwent processes such as evaporation, drying, thermal decomposition, and sintering molding to form a metal oxide precursor. The general formula of the manufactured metal oxide precursor product is represented as FM6535.

[0086] The particle size distribution curve of the metal oxide precursor produced in this example is as shown in Fig. 6. The particle size distribution curve of the metal oxide precursor is a normal curve with a single peak width distribution. And the particle size distribution curve function f(x) is as follows when 0.255 ≦ x ≦ 3.08:

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[0087] Example 4 A nickel salt, a cobalt salt, and a manganese salt were prepared in a mixed metal salt solution at a ratio of 80:10:10 in terms of the molar ratio of metal atoms. Next, under the conditions of a liquid supply flow rate of 0.35 m 3 / h and an atomization pressure of 0.8 MPa, the mixed metal salt solution was put into a firing furnace in the form of droplets. Under the condition of a thermal decomposition temperature of 650 °C, the droplets underwent processes such as evaporation, drying, thermal decomposition, and sintering molding to form a metal oxide precursor. The general formula of the produced metal oxide precursor product is represented as NCM811.

[0088] The particle size distribution of the metal oxide precursor produced in this example is a normal curve with a single peak width distribution. And the particle size distribution curve function f(x) is as follows when 0.257 ≦ x ≦ 1.89:

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[0089] Example 5 A nickel salt, a cobalt salt, a manganese salt, and a titanium salt are prepared in a mixed metal salt solution at a ratio where the molar ratio of metal atoms is 60:10:20:10. Next, at a liquid supply flow rate of 0.5 m 3 / h and an atomization pressure of 0.6 MPa, the mixed metal salt solution is put into a firing furnace in the form of droplets. Under the condition of a thermal decomposition temperature of 800 °C, the droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering and forming to form a metal oxide precursor. The general formula of the manufactured metal oxide precursor product is represented as NCMT6121.

[0090] The particle size distribution of the metal oxide precursor manufactured in this example is a normal curve of a single-peak width distribution. And the particle size distribution curve function f(x) is such that when 0.216 ≤ x ≤ 3.03,

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[0091] Comparative Example 1 A nickel salt, an iron salt, and a manganese salt are prepared in a mixed metal salt solution at a ratio where the molar ratio of metal atoms is 1:1:1. Next, at a liquid supply flow rate of 0.25 m 3 / h and an atomization pressure of 0.35 MPa, the mixed metal salt solution is put into a firing furnace in the form of droplets. Under the condition of a thermal decomposition temperature of 500 °C, the droplets undergo processes such as evaporation, drying, thermal decomposition, and sintering and forming to form a metal oxide precursor. The general formula of the manufactured metal oxide precursor product is represented as NFM111.

[0092] The surface morphology of the metal oxide precursor manufactured in this comparative example is as shown in Fig. 7, and it can be seen that the aggregation phenomenon of the metal oxide precursor is extremely serious.

[0093] The particle size distribution curve of the metal oxide precursor produced in this comparative example is shown in Figure 8. It can be seen that the particle size distribution of the metal oxide precursor is broad and exhibits a bimodal distribution, and does not satisfy the particle size distribution curve function f(x) of the example of the present application.

[0094] Comparative Example 2 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 0.85m 3 Under conditions of a feed flow rate of 1 / h and an atomization pressure of 0.7 MPa, a mixed metal salt solution is placed in a firing 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.

[0095] The particle size distribution curve of the metal oxide precursor produced in this comparative example is shown in Figure 9. It can be seen that the particle size distribution of the metal oxide precursor is broad and exhibits a bimodal distribution, and does not satisfy the particle size distribution curve function f(x) of the example of the present application.

[0096] Comparative Example 3 Nickel salt, cobalt salt, and manganese salt were prepared as a mixed metal salt solution in a ratio of 8:1:1 for the molar ratio of metal atoms, and then 0.3m 3 Under conditions of a feed flow rate of 1 / h and an atomization pressure of 0.2 MPa, a mixed metal salt solution is placed in a firing 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 NCM811.

[0097] The metal oxide precursor produced in this comparative example has a large particle size, and its irregular aggregation phenomenon is extremely severe.

[0098] The particle size distribution curve of the metal oxide precursor produced in this comparative example exhibits an extremely narrow unimodal distribution, and its particle size distribution curve function f(x) is given by the case 0.315≦x≦1.54.

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[0099] Based on the particle size distribution curves of the metal oxide precursors produced in Examples 1 - 5 and Comparative Examples 1 and 3, the measured particle size distribution parameters are shown in Table 1 below.

[0100]

Table 1

[0101] As can be seen from the above measurement results, when the particle size distribution of the single crystal particles in the metal oxide precursor of the example of the present application satisfies the particle size distribution curve function f(x) of the present application, the tap density of the produced metal oxide precursor is 1.2 g / cm 3 -3.5 g / cm 3 That is. Having a high tap density is advantageous for improving the packing rate and compaction density of the cathode material, and further improving the volume specific capacity of the battery.

[0102] Application Example The metal hydroxide precursors produced in Examples 1 - 5 and Comparative Examples 1 and 3 and sodium carbonate were mixed at a molar ratio of 1:1, then placed in a muffler furnace, heated to 900 °C at a heating rate of 5 °C / min under an air atmosphere, sintered at a constant temperature for 15 h, naturally cooled, and then pulverized and sieved to obtain a cathode material.

[0103] The produced cathode material was used to manufacture a sodium ion coin battery, and the charge-discharge performance was measured under voltage conditions of 2 V - 4.15 V. The measurement results are shown in Figure 10 and Table 2 below.

[0104]

Table 2

[0105] As can be seen from Figure 10 and Table 2, the cathode materials produced in Examples 1-5 had high initial discharge ratio capacities under voltage conditions of 2V-4.15V, reaching a maximum of approximately 167.8mAh / g. Comparative Example 1 showed a significantly lower initial discharge ratio capacity compared to Example 1, and Comparative Example 2 showed a significantly inferior initial discharge ratio capacity compared to Example 2. Therefore, the metal oxide precursors of the examples of this application can satisfy a specific monomodal normal particle size distribution curve of 1.2g / cm³. 3 -3.5g / cm 3 In addition to having a high tap density, it can be widely applied to different elements, proportions, and manufacturing conditions, which is advantageous for improving the packing rate and compaction density of the positive electrode material, and further improves the volumetric capacity of sodium-ion batteries.

[0106] The technical features of the above embodiments can be combined in any way, and for the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as these combinations of technical features are inconsistent, they should be considered to fall within the scope described herein.

[0107] The foregoing are merely selectable embodiments of the present invention and do not limit it. To those skilled in the art, the present invention is subject to various modifications and changes. 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.

Claims

1. A metal oxide precursor, The metal oxide precursor has a single-crystal structure, and the particle size distribution curve function f(x) of the metal oxide precursor shows the corresponding volume fraction at particle size x, satisfying the following conditions: (1) When a ≤ x ≤ b, [Math 1] (2) When b < x ≤ c, [Math 2] (3) When x c, f(x) = 0, Of these, 0.214 μm ≤ a ≤ 0.260 μm, 1.78 μm ≤ b ≤ 3.1 μm, 8.2 μm ≤ c ≤ 31.2 μm, ε, μ １ , μ ２ These are all error coefficients, where -1.5 ≤ ε ≤ 1.5 and -0.35 ≤ μ １ ≤0.35, -3 ≤μ ２ A metal oxide precursor characterized by having a value of ≤10.

2. The metal oxide precursor according to claim 1, characterized in that the particle size distribution curve function f(x) of the metal oxide precursor exhibits a unimodal normal particle size distribution curve.

3. The peak value of the particle size distribution curve function f(x) of the aforementioned metal oxide precursor is f(x). ｍａｘ The metal oxide precursor according to claim 1, characterized in that the ratio is 5-10.

4. The metal oxide precursor according to claim 1, characterized in that the full width at half maximum of the particle size distribution curve function f(x) of the metal oxide precursor is 3 μm to 5 μm.

5. The cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D ｎ Therefore, n% = Σf(x), and the cumulative particle size distribution curve function is D ２５ The metal oxide precursor according to claim 1, characterized in that, in this case, 0.5 μm ≤ x ≤ 2.0 μm.

6. The cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D ｎ where n% = Σf(x), and when the cumulative particle size distribution curve function is D ５０ The metal oxide precursor according to claim 1, characterized in that 1.2 μm ≤ x ≤ 3.8 μm

7. The cumulative particle size distribution curve function corresponding to the particle size distribution curve function f(x) of the metal oxide precursor is D ｎ Therefore, n% = Σf(x), and the cumulative particle size distribution curve function is D ７５ The metal oxide precursor according to claim 1, characterized in that, in this case, 2 μm ≤ x ≤ 5 μm.

8. The metal oxide precursor according to claim 1, characterized in that the particle size distribution span value of the particle size distribution curve function f(x) of the metal oxide precursor is 1.0-2.

5.

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

10. The metal oxide precursor according to claim 1, characterized in that the metal oxide precursor is cubic.

11. The tap density of the metal oxide precursor is 1.2 g / cm³. ３ -3.5 g / cm ３ A metal oxide precursor according to any one of claims 1 to 10, characterized in that it is the metal oxide precursor described above.

12. A method for producing a metal oxide precursor according to any one of claims 1 to 11, selected from a spray pyrolysis method.

13. The method for producing a metal oxide precursor according to claim 12, characterized in that the thermal decomposition temperature of the spray pyrolysis method is 550°C to 950°C.

14. The method for producing a metal oxide precursor according to claim 12, characterized in that the atomization pressure of the spray pyrolysis method is 0.35 MPa - 0.7 MPa.

15. The feed liquid flow rate obtained by the aforementioned spray pyrolysis method was 0.3 m 3 / h-0.8m 3 A method for producing a metal oxide precursor according to claim 12, characterized in that the value is / h.

16. A cathode material produced from a metal oxide precursor according to any one of claims 1 to 11 or a metal oxide precursor produced by the method according to any one of claims 12 to 15.

17. It is a positive electrode sheet, 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 16.

18. A secondary battery characterized by including the positive electrode sheet described in claim 17.

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