Cathode material precursor, single crystal cathode material, and manufacturing method, lithium-ion battery

Abstract

Cathode material precursor, single crystal cathode material and manufacturing method, lithium-ion battery, wherein the general chemical formula of the single crystal cathode material is Li x Ni a Co b Mn c N d O2, where 0.98 ≤ x ≤ 1.1, 0.50 ≤ a ≤ 0.98, 0

Description

[Technical Field]

[0001] This application relates to the field of cathode material technology, and more particularly to cathode material precursors, single-crystal cathode materials, manufacturing methods, and lithium-ion batteries. [Background technology]

[0002] Lithium-ion cathode materials are mainly divided into lithium iron phosphate and ternary materials. Lithium iron phosphate is superior to ternary materials in terms of cost, cycle life, and thermal stability, and is therefore applied to commercial vehicles, mid-range and low-end passenger cars, and energy storage. Ternary materials have high energy density and excellent low-temperature performance, and are applied to mid-range and high-end passenger cars.

[0003] Conventional polycrystalline ternary cathode materials are constructed by tightly aggregating primary particles (hundreds of nanometers) to form spherical secondary particles (usually >10 μm in diameter). During the charge-discharge process, the shrinkage of the crystal lattice easily generates localized stress along the grain boundaries, causing the material structure to collapse, forming fine cracks and rapidly reducing the capacitance of the cathode material. Single crystallization is one way to improve the cycle performance of ternary materials. Single-crystal ternary materials are composed of dispersed primary particles (generally several micrometers in diameter, and most particles are single crystal grains with the same orientation), and there are no secondary spherical particles. Because grain boundaries are eliminated, cracking of the cathode material during the charge-discharge process can be suppressed, resulting in excellent stability. However, single-crystal ternary materials also face other problems. Due to the long diffusion pathway of Li in single-crystal ternary materials, the transmission power of Li is slow, resulting in a high DC internal resistance (DCR) and poor rate characteristics. Furthermore, although single-crystal grains can suppress particle cracking, phenomena such as crystal plane slippage and displacement still occur during the cycle process, leading to the formation of even finer cracks.

[0004] Ternary single-crystal cathode materials are generally manufactured by high-temperature sintering from precursor compounds containing Ni / Co / Mn and lithium salts. During the sintering process, the formation of the cathode material is usually very slow and the growth rate is non-uniform, leading to stress concentration within the formed cathode material. Furthermore, ion diffusion is limited, resulting in concentration differences in the elemental distribution within the ternary material and mismatched crystal lattice parameters within the material. This inhibits lithium ion transmission, increasing the resistance of the cathode material and degrading its rate characteristics. Additionally, minute stresses in the internal crystal lattice cause cracking and pulverization during the cathode material's cycling process, reducing its cycling performance.

[0005] Therefore, improving the rate characteristics of single-crystal cathode materials, reducing resistance, and further enhancing cycle performance are currently technical problems that need to be solved. [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of this application is to provide a cathode material precursor, a single-crystal cathode material, a manufacturing method, and a lithium-ion battery. The single-crystal cathode material provided in this application has low crystal lattice distortion, which reduces the diffusion energy barrier of lithium ions between microcrystals and improves the Li ion diffusion coefficient. As a result, the single-crystal cathode material exhibits a low DCR, has excellent rate characteristics, and reduces the occurrence of phenomena such as crystal plane slip and displacement. This suppresses the occurrence of fine cracks, improves the structural stability of the single-crystal cathode material, and further improves the cycle performance of the single-crystal cathode material. [Means for solving the problem]

[0007] In a first embodiment, the embodiment of the present application provides a single-crystal cathode material, the general chemical formula of the single-crystal cathode material is Li x Ni a Co b Mn c N dO2, where 0.98 ≦ x ≦ 1.1, 0.50 ≦ a ≦ 0.98, 0 < b ≦ 0.20, 0 < c ≦ 0.30, 0 ≦ d ≦ 0.10, and a + b + c + d = 1. N contains at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y. When observing the single-crystalline cathode material with a scanning electron microscope, 10 points are randomly selected for EDS point scanning to measure the Ni, Co, and Mn contents at a magnification of 3K. In the EDS spectrum results of the single-crystalline cathode material, the standard deviation of the mass contents of various elements of Ni, Co, and Mn in the single-crystalline cathode material is all ≦ 0.03. The lattice strain of the single-crystalline cathode material is ε, and ε < 0.2%.

[0008] In some embodiments, the single-crystalline cathode material contains SO4 2- and the content of SO4 2- is δ, where 0 ppm ≦ δ ≦ 800 ppm.

[0009] In some embodiments, the single-crystalline cathode material contains at least one single crystal grain with the same orientation, where the average particle size of the single crystal grain is 1 μm to 5 μm.

[0010] In some embodiments, the size of the crystal grains of the single-crystalline cathode material is D, and 150 nm < D < 250 nm.

[0011] In some embodiments, the average particle size D 50 of the single-crystalline cathode material is 1.5 μm to 5 μm.

[0012] In some embodiments, the better tap density (tap density measured by a tap density tester from Bettersize) of the single-crystalline cathode material is > 1.5 g / cm 3 .

[0013] In some embodiments, the range of the mass content of each of the elements Ni, Co, and Mn in the single-crystal cathode material is all ≤ 0.08.

[0014] In a second aspect, an embodiment of the present application provides a cathode material precursor, and the chemical general formula of the cathode material precursor is Ni a Co b Mn c N d O e where 0.50 ≤ a ≤ 0.98, 0 < b ≤ 0.20, 0 < c ≤ 0.30, 0 ≤ d ≤ 0.10, a + b + c + d = 1, 1 ≤ e ≤ 1.15, and N contains at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y. The weighted average diameter of the surface area of the cathode material precursor is D[3,2] < 2.0 μm, and the standard deviation of the mass content of each of the elements Ni, Co, and Mn in the cathode material precursor is all ≤ 0.05.

[0015] In some embodiments, the range of the mass content of each of the elements Ni, Co, and Mn in the cathode material precursor is all ≤ 0.12.

[0016] In some embodiments, the cathode material precursor includes secondary particles, and the secondary particles include a plurality of aggregated primary particles.

[0017] In some embodiments, the cathode material precursor includes secondary particles, the secondary particles include a plurality of aggregated primary particles, and the primary particles are spherical.

[0018] In some embodiments, the cathode material precursor includes secondary particles, the secondary particles include a plurality of aggregated primary particles, and the particle diameter of the primary particles is 20 nm to 1000 nm.

[0019] In some embodiments, the average particle diameter D 50 of the cathode material precursor is < 3.5 μm.

[0020] In some embodiments, the specific surface area of ​​the cathode material precursor is >5m². 2 It is / g.

[0021] In some embodiments, the better tap density of the cathode material precursor is >1 g / cm³ 3 That is the case.

[0022] In a third embodiment, the embodiment of the present application provides a method for manufacturing a single-crystal cathode material, comprising the following steps. A mixed solution containing nickel salt, cobalt salt, and manganese salt is subjected to atomization treatment, followed by thermal decomposition to obtain a cathode material precursor. The surface area weighted average diameter of the cathode material precursor is D[3,2] < 2.0 μm, and the standard deviations of the mass content of each element Ni, Co, and Mn in the cathode material precursor are all ≤ 0.05. After mixing the cathode material precursor with a lithium source, sintering is performed in an oxygen-containing atmosphere to obtain a single-crystal cathode material. The standard deviations of the mass content of each element Ni, Co, and Mn in the single-crystal cathode material are all ≤ 0.03, and the crystal lattice strain of the single-crystal cathode material is ε and ε < 0.2%.

[0023] In some embodiments, the cathode material precursor is SO4 2- Including the SO4 2- The content is η, where 0 ppm ≤ η ≤ 1800 ppm.

[0024] In some embodiments, the nickel salt comprises at least one of nickel chloride, nickel sulfate, nickel nitrate, nickel carbonate, nickel oxalate, and nickel acetate.

[0025] In some embodiments, the cobalt salt comprises at least one of cobalt chloride, cobalt oxalate, cobalt carbonate, cobalt sulfate, cobalt nitrate, and cobalt acetate.

[0026] In some embodiments, the manganese salt includes at least one of manganese chloride, manganese carbonate, manganese sulfate, manganese oxalate, manganese nitrate, and manganese acetate.

[0027] In some embodiments, the molar ratio of Ni, Co, and Mn in the mixed solution is (50~98):(0~20):(0~30), and the contents of Co and Mn in the mixed solution are not zero.

[0028] In some embodiments, the total metal concentration in the mixed solution is 200 g / L to 500 g / L.

[0029] In some embodiments, the mixed solution further includes a dopant containing N element, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y.

[0030] In some embodiments, the chemical general formula of the cathode material precursor is Ni a Co b Mn c N d O e where 0.50≦a≦0.98, 0<b≦0.20, 0<c≦0.30, 0≦d≦0.10, a + b + c + d = 1, 1≦e≦1.15, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y.

[0031] In some embodiments, the range of the mass content of each element of Ni, Co, and Mn in the cathode material precursor is all ≦0.12.

[0032] In some embodiments, the flow rate of the mixed solution is 100 L / h to 900 L / h.

[0033] In some embodiments, the pressure of the atomization treatment is 0.4 MPa to 0.8 MPa.

[0034] In some embodiments, the temperature of the primary sintering is 500°C to 850°C.

[0035] In some embodiments, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium ethaneate, lithium sulfate, lithium chloride, lithium nitrate, and lithium oxalate.

[0036] In some embodiments, the molar ratio of lithium in the lithium source to the total amount of nickel, cobalt, and manganese in the cathode material precursor is 0.98 to 1.10.

[0037] In some embodiments, the sintering temperature is 750°C to 950°C.

[0038] In some embodiments, the sintering time is 10 to 30 hours.

[0039] In a fourth embodiment, an embodiment of the present application provides a lithium-ion battery comprising a single-crystal cathode material manufactured by the single-crystal cathode material described in the first embodiment or by the method for manufacturing the single-crystal cathode material described in the third embodiment. [Effects of the Invention]

[0040] Compared to the prior art, the technical solution of this application has at least the following beneficial effects. The single-crystal cathode material provided in this application was subjected to EDS point scanning at 10 randomly selected points to measure the Ni, Co, and Mn content. The EDS spectral results of the single-crystal cathode material showed that the standard deviations of the mass content of each element, Ni, Co, and Mn, were all ≤0.03, indicating high uniformity in the distribution of Ni, Co, and Mn elements within the single-crystal cathode material. This is advantageous in reducing defects in the crystal structure of the single-crystal cathode material. The crystal lattice strain of the single-crystal cathode material is ε < 0.2%, which lowers the diffusion energy barrier of lithium ions between microcrystals and improves the Li ion diffusion coefficient. This allows the single-crystal cathode material to exhibit excellent rate characteristics and a low DCR. Furthermore, the low crystal lattice strain suppresses the occurrence of fine cracks within the single-crystal cathode material, further improving the cycle performance of the single-crystal cathode material.

[0041] The positive electrode material precursor provided in this application has a surface area weighted average diameter D[3,2] < 2.0 μm, exhibits high reaction activity, and is advantageous in improving reaction efficiency and mass transfer efficiency in the subsequent process of manufacturing the positive electrode material. Furthermore, the standard deviations of the mass content of each element, Ni, Co, and Mn, in the positive electrode material precursor obtained by the above manufacturing method are all ≤ 0.05, indicating high uniformity of the distribution of Ni, Co, and Mn elements in the positive electrode material precursor. By using this positive electrode material precursor to manufacture a positive electrode material, the uniformity of the distribution of Ni, Co, and Mn elements in the positive electrode material can be improved. The positive electrode material manufactured using this positive electrode material precursor has fewer defects in the crystal structure and low crystal lattice stress.

[0042] The present invention provides a method for producing a single-crystal cathode material, which involves atomizing a mixed solution containing a nickel salt, a cobalt salt, and a manganese salt, followed by thermal decomposition to obtain a cathode material precursor. The surface area weighted average diameter of the cathode material precursor is D[3,2] < 2.0 μm, indicating high reaction activity, which is advantageous for improving reaction efficiency and mass transfer efficiency in the subsequent high-temperature sintering process of the cathode material precursor and lithium source. Furthermore, the standard deviations of the mass content of each element, Ni, Co, and Mn, in the cathode material precursor obtained by the above production method are all ≤ 0.05, indicating high uniformity of the distribution of Ni, Co, and Mn in the cathode material precursor. Moreover, in the single-crystal cathode material produced by subsequently sintering the above cathode material precursor with a lithium source, the standard deviations of the mass content of each element, Ni, Co, and Mn, are... The metric deviations are all ≤0.03, indicating high uniformity in the distribution of Ni, Co, and Mn elements within the single-crystal cathode material. This is advantageous in reducing defects in the crystal structure of the single-crystal cathode material. Furthermore, the crystal lattice strain of the single-crystal cathode material is low, with ε < 0.2%. This reduces the diffusion energy barrier for lithium ions between microcrystals, improving the Li ion diffusion coefficient. This allows the single-crystal cathode material to exhibit excellent rate characteristics and a low DCR. In addition, the low crystal lattice strain suppresses the occurrence of fine cracks within the single-crystal cathode material, further improving the cycle performance of the single-crystal cathode material. [Brief explanation of the drawing]

[0043] The present application will be further described below with reference to the drawings and embodiments. [Figure 1] This is an SEM morphological view of the cathode material precursor manufactured in Example 1 of the present application. [Figure 2] This is another SEM morphological view of the cathode material precursor manufactured in Example 1 of this application. [Figure 3] This is the EDS spectrum result of the cathode material precursor manufactured in Example 1 of the present application. [Figure 4] This is the Williamsone-Hall analysis fitting curve for the single-crystal cathode material manufactured in Example 1 of this application.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] To better understand the technical solution of the present application, the embodiments of the present application will be described in detail below with reference to the drawings.

[0045] Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0046] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0047] It should be understood that the term " / and / or" used in this specification is only for explaining the relationship between related objects and indicates that three types of relationships may exist. For example, A and / or B includes three cases: when A exists alone, when A and B exist simultaneously, and when B exists alone. Also, in this specification, the character " / " generally indicates that the related objects before and after are in an "or" relationship.

[0048] In a first aspect, the embodiment of the present application provides a single crystal cathode material, and the chemical general formula of the single crystal cathode material is Li x Ni a Co b Mn c N d O2, where 0.98 ≦ x ≦ 1.1, 0.50 ≦ a ≦ 0.98, 0 < b ≦ 0.20, 0 < c ≦ 0.30, 0 ≦ d ≦ 0.10, a + b + c + d = 1, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn and Y, When observing the single-crystal cathode material with a scanning electron microscope, 10 random points are selected from the single-crystal cathode material at a magnification of 3K and EDS point scanning is performed to measure the Ni, Co, and Mn content. In the EDS spectral results of the single-crystal cathode material, the standard deviations of the mass content of each element, Ni, Co, and Mn, are all ≤0.03. The crystal lattice strain of the single-crystal cathode material is ε, and ε < 0.2%.

[0049] The single-crystal cathode material provided in this application was subjected to EDS point scanning at 10 randomly selected points to measure the Ni, Co, and Mn content. The EDS spectral results of the single-crystal cathode material showed that the standard deviations of the mass content of each element, Ni, Co, and Mn, were all ≤0.03, indicating high uniformity in the distribution of Ni, Co, and Mn elements within the single-crystal cathode material. This is advantageous in reducing defects in the crystal structure of the single-crystal cathode material. The crystal lattice strain of the single-crystal cathode material is ε < 0.2%, which lowers the diffusion energy barrier of lithium ions between microcrystals and improves the Li ion diffusion coefficient. This allows the single-crystal cathode material to exhibit excellent rate characteristics and a low DCR. Furthermore, the low crystal lattice strain suppresses the occurrence of fine cracks within the single-crystal cathode material, further improving the cycle performance of the single-crystal cathode material.

[0050] Specifically, the possible values ​​of x are not limited to 0.98, 0.99, 1.0, 1.01, 1.03, 1.05, 1.08, 1.09, or 1.1.

[0051] The possible values ​​for a may be 0.50, 0.55, 0.60, 0.63, 0.70, 0.75, 0.80, 0.85, 0.88, 0.90, 0.95, or 0.98, for example; the possible values ​​for b may be 0.01, 0.05, 0.08, 0.10, 0.11, 0.13, 0.15, 0.18, or 0.20, for example; the possible values ​​for c may be 0.01, 0.05, 0.10, 0.15, 0.18, 0.20, 0.23, 0.27, or 0.30, for example; and the possible values ​​for d may be 0, 0.01, 0.03, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.10, for example, and are not limited thereto.

[0052] Specifically, the standard deviations of the mass content of each element, Ni, Co, and Mn, in the single-crystal cathode material may be, but are not limited to, 0.01, 0.015, 0.02, 0.025, 0.026, 0.028, or 0.03.

[0053] In some embodiments, the range of mass content of each element, Ni, Co, and Mn, in the single-crystal cathode material is ≤0.08, and may specifically be 0.01, 0.02, 0.028, 0.03, 0.05, 0.057, 0.06, 0.07, 0.075, or 0.08, and may, of course, be other values ​​within the above range, and is not limited thereto.

[0054] As can be understood, the smaller the standard deviation and range of the mass content of each element, Ni, Co, and Mn, in a single-crystal cathode material, the higher the uniformity of the distribution of Ni, Co, and Mn in the single-crystal cathode material. The standard deviation and range of the mass content of each element, Ni, Co, and Mn, in the single-crystal cathode material of this application are within the above range, demonstrating that the distribution of Ni, Co, and Mn in the single-crystal cathode material of this application is uniform, which is advantageous in reducing crystal lattice defects in the single-crystal cathode material, lowering crystal lattice stress, and improving the cycle performance and rate characteristics of the single-crystal cathode material.

[0055] The crystal lattice strain of the single-crystal cathode material may be, but is not limited to, 0.01%, 0.03%, 0.05%, 0.08%, 0.10%, 0.11%, 0.12%, 0.15%, 0.18%, or 0.19%.

[0056] In some embodiments, the single-crystal cathode material further comprises a coating layer comprising a metal oxide or a lithium-ion conductor, wherein the metal in the metal oxide comprises at least one of Al, Ti, Zr, Y, Nb, Mg, W, B, Ce, Co, and Mn. The coating layer can reduce direct contact between the single-crystal cathode material and the electrolyte, reduce the occurrence of side reactions between the material and the electrolyte, and further improve the electrochemical performance of the single-crystal cathode material.

[0057] In some embodiments, free SO4 on the surface of the single-crystal cathode material 2- The content is 1000 ppm or less, preferably ≤800 ppm. SO4 in single crystal cathode material 2- The content may specifically be 0 ppm, 5 ppm, 10 ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, or 1000 ppm, etc. Free SO4 2- When the content is within the above range, the cathode material has better rate and cycle characteristics. Conventional ternary precursor materials use NiSO4, CoSO4, and MnSO4 as raw materials in the manufacturing process, so the coprecipitation precursor retains a high content of sulfate ions. Since sulfate ions are difficult to decompose, the sulfate ion content on the surface of the corresponding cathode material formed by subsequent sintering is high (usually >1000 ppm). Free sulfate ions adversely affect the electrochemical performance of the cathode material. Free SO4 on the surface 2- If the content is high, SO@ 2- It binds to Li ions, trapping some of them, causing a deterioration in the material's capacity and rate, and also releasing SO4 from the surface. 2- This also affects the stability of the SEI film.

[0058] SO4 free on the surface of the single-crystal cathode material 2- The content is due to the release of SO4 on the surface of the cathode material precursor. 2- It has a high content and very strong inheritance properties, and is a cathode material precursor with SO4 2- The higher the content, the more free SO4 is released on the surface of the single-crystal cathode material. 2- The content of SO4 increases. Free SO4 is released on the surface of the cathode material precursor provided in this application. 2- The content is ≤1000 ppm, and the amount of free SO4 on the surface is ≤1000 ppm. 2- It is easy to manufacture cathode materials with a content of ≤800 ppm.

[0059] SO4 in single-crystal cathode material precursors 2- To reduce the content, in some examples, the Ni salt, Mn salt, Co salt, and N salt each independently contain at least one of the chloride, nitrate, oxalate, and acetate salts. The nitrates, chlorides, oxalates, and acetates of nickel, cobalt, and manganese decompose very readily at high temperatures, leaving no obvious residue, and therefore do not fundamentally affect the performance of the cathode material. SO4 in metal salt mixed solution 2- By controlling the content of SO4 2- It is possible to manufacture cathode material precursors with a content of SO4 close to zero. However, this requires a high purity of raw materials, leading to increased raw material costs. 2- Using Ni, Co, Mn, and N sources in a ternary recovery material containing impurities as metal sources, SO4 2- Manufacturing cathode material precursors by controlling the content of [a specific element] is more economical.

[0060] In some examples, in the metal salt mixed solution, the total mass of Ni, Co, and Mn elements is used as the basis for SO4 2- The content is ≤800 ppm, and furthermore, the SO4 released on the surface 2- It is advantageous to manufacture single-crystal cathode materials with a low content of [substance name], and to further improve the capacity and rate characteristics of the single-crystal cathode material.

[0061] In some embodiments, the single-crystal cathode material comprises at least one single crystal grain having the same orientation, wherein the average particle size of the single crystal grain is 1 μm to 5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0062] The cathode material single crystal particles of this application contain at least one single crystal grain with the same orientation, and the single particle satisfying the above conditions has an average particle diameter of 1 to 5 μm as measured and read by EBSD testing. It can stably achieve filling its own height and can prevent the occurrence of cracks due to causes such as particle compression after the particles reach their closest-packed deposition. The particles having the same orientation can alleviate stress strain during the charge-discharge cycle process of the cathode particles, significantly reducing particle cracking during the cycle process, and thereby greatly improving the structural stability of the cathode particles.

[0063] Furthermore, the orientation of the crystal grains of the positive electrode material is tested at least by electron backscatter diffraction (EBSD). 100 single crystal grains with the same orientation are randomly selected, and the particle size of each crystal grain is measured. The arithmetic mean is taken as the average particle size of the single crystal grains.

[0064] The difference between single-crystal cathode materials and polycrystalline ternary cathode materials (i.e., polycrystalline secondary particles) is that the smallest particles in polycrystalline secondary particles are secondary particles formed by the aggregation of primary particles. In single-crystal cathode materials, the smallest particles are typically monomeric primary particles at the micrometer level. Generally, in addition to EBSD testing, it is possible to determine whether the cathode product obtained is a single-crystal material by characterization methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Compared to conventional single-crystal cathode materials, SEM is also important and is a reliable characterization method, and the external shape of the single-crystal particles generally shows a regular or irregular polyhedral shape with no significant particle aggregation. TEM is a supplementary second characterization method, and it is used to observe whether the orientation of the crystal planes of the obtained product matches, and further characterization is performed by referring to limited-field electron diffraction (SAED). All of the above methods can be used to determine whether or not it is a single-crystal cathode material. For ease of understanding, the single-crystal cathode material of the present invention can be understood as a cathode material particle comprising at least one single crystal grain having the same orientation, wherein the average particle size of the single crystal grain is 1 μm to 5 μm.

[0065] As can be understood, a single crystal grain in this application may be a single particle composed of one primary particle. The above single-crystal cathode material may contain a small amount of "quasi-secondary particles" formed by the bonding of several single particles. A "primary particle" is the smallest particle unit that can be identified when the cathode active material is observed with a scanning electron microscope, and a "secondary particle" is a secondary structure formed by the aggregation of multiple primary particles, exhibiting a rounded, spherical shape. A "quasi-secondary particle" is formed by the bonding of several single particles, and typically the particle diameter of a single particle in the above quasi-secondary particle is usually 1 μm to 5 μm, and generally, the degree to which the particles are rounded is lower than that of the above conventional "secondary particles".

[0066] Note that it should be noted that the "single-crystalline cathode material" known to those skilled in the art is not a "single crystal" in the strict sense. Crystallographically, an ideal single crystal is a crystal having exactly the same arrangement and direction. However, limited to impurities, strains, and crystal defects, ideal single crystals are very rare and difficult to produce even in laboratories. Therefore, the single-crystalline cathode materials well-known in the industry are actually "quasi-single-crystalline form" cathode materials, which show large particle sizes of quasi-single crystals in terms of dimensions and are distinguished from polycrystals composed of a plurality of small primary particles.

[0067] In some embodiments, the size of the crystal grains of the single-crystalline cathode material is D, where 150 nm < D < 250 nm. Specifically, the size of the crystal grains of the single-crystalline cathode material may be, for example, 151 nm, 155 nm, 160 nm, 170 nm, 185 nm, 190 nm, 200 nm, 205 nm, 230 nm, or 245 nm, etc., and is not limited herein. If the size of the crystal grains of the single-crystalline cathode material is less than 150 nm, the cycle stability of the single-crystalline cathode material is poor. If the size of the crystal grains of the single-crystalline cathode material is greater than 250 nm, the capacity and rate performance of the single-crystalline cathode material are inferior. Controlling the size of the crystal grains of the single-crystalline cathode material within the above range is advantageous for improving the electrochemical performance of the single-crystalline cathode material.

[0068] Note that the calculation method of the crystal grain size is generally calculated by the Scherrer equation using the full width at half maximum. This method assumes that the stress of the crystal lattice is 0 and the broadening of the diffraction peak is completely due to the crystal particle size. However, in reality, the crystal lattice stress inside the single-crystalline cathode material cannot be completely ignored, and many factors cause stress concentration inside the single-crystalline cathode material. Therefore, the crystal grain size calculated by the Scherrer equation has its inherent limitations. In this application, the Williamson-Hall method is used to separate the broadening of the diffraction peak caused by the size of the microcrystals and the broadening of the diffraction peak caused by the stress of the crystal lattice. Therefore, the calculated crystallite size can better reflect the electrochemical performance of the reaction material.

[0069] In some embodiments, the average particle size D of the single-crystalline cathode material50 The particle size is 1.5 μm to 5 μm, and specifically may be 1.5 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm, and of course may be other values ​​within the above range, and is not limited thereto. Controlling the particle size of the single-crystal cathode material within the above range is advantageous for improving the structural stability, thermal stability, and long-cycle stability of the single-crystal cathode material.

[0070] In some embodiments, the better tap density of the single-crystal cathode material is >1.5 g / cm³. 3 Specifically, it is 1.55 g / cm³. 3 1.58 g / cm³ 3 , 1.62 g / cm³ 3 1.63 g / cm³ 3 1.65 g / cm³ 3 1.70 g / cm³ 3 Or 1.75 g / cm³ 3 It may be any other value, and of course, it may be any other value within the above range, and is not limited thereto. When the tap density of the single crystal cathode material is controlled within the above range, it is advantageous to improve the energy density of the battery made of the single crystal cathode material.

[0071] In some embodiments, the compacted desity of the single-crystal cathode material is >3.0 g / cm³. 3 Specifically, it is 3.1 g / cm³. 3 3.2 g / cm³ 3 3.3 g / cm³ 3 3.5 g / cm³ 3 3.7 g / cm³ 3 3.9 g / cm³ 3 Or 4.1 g / cm³ 3 It could be any other value within the above range, and is not limited thereto.

[0072] In a second embodiment, the embodiment of the present application provides a cathode material precursor, the general chemical formula of the cathode material precursor is Ni a Co b Mn c N d Oe where 0.50 ≦ a ≦ 0.98, 0 < b ≦ 0.20, 0 < c ≦ 0.30, 0 ≦ d ≦ 0.10, a + b + c + d = 1, 1 ≦ e ≦ 1.15, N contains at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y, The volume - weighted average diameter of the surface area of the cathode material precursor is D[3,2] < 2.0 μm, and the standard deviation of the mass content of each type of element of Ni, Co, and Mn in the cathode material precursor is all ≦ 0.05.

[0073] In the prior art, in the reaction process between the cathode material precursor and the lithium salt, it is limited to the ion diffusion rate and the temperature gradient. There are differences in the crystal growth rate of each micro - region inside the material, and there are also differences in the unit cell parameters, which causes the accumulation of crystal lattice stress inside the material. The crystal lattice stress increases the diffusion energy barrier between each crystal plane / grain boundary of Li ions, reduces the diffusion coefficient of Li ions, and ultimately increases the DCR of the material. The morphology and structural characteristics of the cathode material precursor have good inheritance for the cathode material. Therefore, the composition and structure of the cathode material precursor directly affect the performance of the final cathode material. The cathode material precursor provided in the present application has a volume - weighted average diameter of the surface area of the cathode material precursor of D[3,2] < 2.0 μm, high reaction activity, which is beneficial to improving the reaction efficiency and mass transfer efficiency in the process of subsequently manufacturing the cathode material from the cathode material precursor. Also, the standard deviation of the mass content of each type of element of Ni, Co, and Mn in the cathode material precursor obtained by the above manufacturing method is all ≦ 0.05, indicating a high uniformity in the distribution of Ni, Co, and Mn elements in the cathode material precursor. Using this cathode material precursor to manufacture a cathode material can improve the uniformity of the distribution of Ni, Co, and Mn elements in the cathode material. The cathode material manufactured from this cathode material precursor has few defects in the crystal structure and small crystal lattice stress.

[0074] In some embodiments, the cathode material precursor contains SO4 2- including, and the SO4 2-The content is η, where 0 ppm ≤ η ≤ 1800 ppm.

[0075] As can be understood, SO4 on the precursor surface 2- It is difficult to decompose and difficult to dope inside the positive electrode material, and therefore free SO4 remains on the surface of the positive electrode material. 2- The content and the amount of SO4 released in the precursor 2- The content of may have a certain degree of inheritance, and SO4 in the precursor 2- The higher the content, the more free SO4 is present on the surface of the ternary cathode material. 2- The content of SO4 increases. Free SO4 is released on the surface of the cathode material precursor provided in this application. 2- The content is ≤1800 ppm, and the amount of free SO4 on the surface is ≤1800 ppm. 2- The content of SO4 makes it easy to manufacture cathode materials with a content of ≤800 ppm. 2- To reduce the content, in some examples, the Ni salt, Mn salt, Co salt, and N salt each independently contain at least one of the chloride, nitrate, oxalate, and acetate salts, thus avoiding the use of nickel sulfate, cobalt sulfate, and manganese sulfate. The nitrates, chlorides, oxalates, and acetates of nickel, cobalt, and manganese decompose very readily at high temperatures, leaving no obvious residue, and therefore do not fundamentally affect the performance of the cathode material. SO4 in metal salt mixed solution 2- By controlling the content of SO4 2- It is possible to manufacture cathode material precursors with a content of SO4 close to zero. However, this requires a high purity of raw materials, leading to increased raw material costs. 2- In a ternary recovery material containing impurities, the Ni source, Co source, Mn source, and N source are used as metal sources, and SO4 is used in the metal source. 2- Manufacturing cathode material precursors by controlling the content of [a specific element] is more economical.

[0076] In some examples, in the metal salt mixed solution, the total mass of Ni, Co, and Mn elements is used as the basis for SO4 2-The content of it is ≤ 1800 ppm. Specifically, it may be 500 ppm, 800 ppm, 1200 ppm, 1600 ppm, 1700 ppm, 1800 ppm, etc., and is not limited herein.

[0077] Industrially, generally, the average particle size D 50 is used to characterize the particle size of the cathode material precursor. However, the reaction between the cathode material precursor and the lithium salt is a process related to the contact area. Therefore, the Sauter average particle size, that is, the surface area weighted average diameter D[3,2], is more suitable for actually characterizing the particle size of the cathode material precursor. The larger D[3,2] is, the smaller the surface activity of the cathode material precursor becomes, and the slower the reaction rate with the lithium salt is.

[0078] In addition, the surface area weighted average diameter D[3,2] of the cathode material precursor in the present application can be directly measured by a Malvern 3000 laser particle size analyzer. Specifically, the formula D[3,2] = (Σy 3 N d ) / (Σy 2 N d ) is calculated and obtained. Here, y is the particle size, and N d is the number of particles with the particle size y.

[0079] Specifically, the surface area weighted average diameter D[3,2] of the cathode material precursor may be 1.98 μm, 1.95 μm, 1.8 μm, 1.75 μm, 1.64 μm, 1.5 μm, 1.3 μm, 1.2 μm, 1.1 μm, 0.8 μm, 0.9 μm, 0.5 μm, etc., and is not limited herein. Controlling the surface area weighted average diameter D[3,2] of the cathode material precursor within the above range is advantageous for improving the reaction activity of the cathode material precursor and the reaction efficiency and mass transfer efficiency in the process of subsequent sintering of the cathode material precursor with the lithium source.

[0080] The standard deviations of the mass content of each element, Ni, Co, and Mn, in the cathode material precursor may be, but are not limited to, 0.001, 0.005, 0.009, 0.01, 0.013, 0.02, 0.025, 0.03, 0.036, 0.04, 0.044, 0.045, 0.047, or 0.049.

[0081] In some embodiments, the range of mass content of each element, Ni, Co, and Mn, in the positive electrode material precursor is ≤0.12, and may specifically be 0.01, 0.015, 0.018, 0.02, 0.029, 0.03, 0.035, 0.048, 0.059, 0.06, 0.08, 0.097, 0.10, 0.105, 0.11, 0.112, 0.115, or 0.119, and may, of course, be other values ​​within the above range, and is not limited thereto.

[0082] As can be understood, the standard deviation and range of the mass content of each element, Ni, Co, and Mn, in the cathode material can reflect the degree of uniformity of the distribution of Ni, Co, and Mn elements in the cathode material precursor. The lower the standard deviation and range of the mass content of each element, the more uniform the distribution of Ni, Co, and Mn elements in the cathode material precursor. Furthermore, the uniformity of the distribution of Ni, Co, and Mn elements in the cathode material precursor and the uniformity of the distribution of Ni, Co, and Mn elements in the single-crystal cathode material have good inheritance properties. The more uniform the distribution of Ni, Co, and Mn elements in the cathode material precursor, the more uniform the distribution of Ni, Co, and Mn elements in the single-crystal cathode material produced from that cathode material precursor.

[0083] Therefore, controlling the standard deviation and range of the mass content of each element, Ni, Co, and Mn, in the cathode material precursor within the above range is advantageous in improving the uniformity of the distribution of Ni, Co, and Mn elements in the single-crystal cathode material. This results in high uniformity of the distribution of Ni, Co, and Mn elements in the single-crystal cathode material, fewer defects in the crystal structure of the single-crystal cathode material, and low crystal lattice distortion.

[0084] In some embodiments, the cathode material precursor comprises secondary particles, the secondary particles comprising a plurality of aggregated primary particles.

[0085] In some embodiments, the cathode material precursor comprises secondary particles, the secondary particles comprising a plurality of aggregated primary particles, and the primary particles exhibit a spherical shape.

[0086] In some embodiments, the cathode material precursor includes secondary particles, which include a plurality of aggregated primary particles, the particle size of which is 20 nm to 1000 nm, specifically 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 500 nm, 800 nm, or 1000 nm, but is not limited to the listed values, and other unlisted values ​​within that range are also applicable. If the particle size of the primary particles is greater than 1000 nm, the reaction activity of the cathode material precursor surface is poor, the lattice distortion of the manufactured single-crystal cathode material is large, and the cycle performance and rate characteristics of the single-crystal cathode material are poor. If the primary particles are smaller than 20 nm, the tap density of the cathode material precursor is low, resulting in a low tap density of the manufactured single-crystal cathode material. Controlling the particle size of the primary particles within the above range is advantageous for improving the cycle performance and rate characteristics of the single-crystal cathode material manufactured from the cathode material precursor.

[0087] In some embodiments, the average particle size D of the positive electrode material precursor 50 The particle size D of the positive electrode material precursor is <3.5 μm, and may specifically be 0.5 μm, 0.8 μm, 1.2 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.2 μm, or 3.5 μm, and of course may be other values ​​within the above range, and is not limited thereto. 50 Controlling this within the above range is advantageous for improving the reaction activity of the cathode material precursor.

[0088] In some embodiments, the specific surface area of ​​the positive electrode material precursor is ≥ 5 m². 2 It is / g, specifically 5m 2 / g, 6m 2 / g, 8 m 2 / g, 10 m 2 / g, 12 m 2 / g, 15 m 2 / g, 20 m 2 / g, 25 m 2 / g, 50 m 2 / g or 100 m 2 It may be / g etc., and of course other values within the above range may also be used, and it is not limited here. The larger the specific surface area of the positive electrode material precursor, the higher the reaction activity of the positive electrode material precursor, which is advantageous for the reaction between the lithium source and the positive electrode material precursor, and can reduce the defects in the crystal lattice of the single crystal positive electrode material manufactured from the positive electrode material precursor.

[0089] In some embodiments, the better tap density of the positive electrode material precursor is >1 g / cm 3 Specifically, it is 1.1 g / cm 3 1.2 g / cm 3 1.3 g / cm 3 1.8 g / cm 3 2.3 g / cm 3 2.5 g / cm 3 or 3 g / cm 3 etc., and of course other values within the above range may also be used, and it is not limited here. When controlling the tap density of the positive electrode material precursor within the above range, it is advantageous to improve the tap density of the manufactured single crystal positive electrode material, thereby improving the energy density of the battery.

[0090] In the third aspect, the embodiments of the present application provide a method for manufacturing a single crystal positive electrode material, including the following steps.

[0091] In step S100, after performing atomization treatment on a mixed solution containing nickel salt, cobalt salt and manganese salt, thermal decomposition is performed to obtain a positive electrode material precursor. The surface area weighted average diameter of the positive electrode material precursor is D[3,2]<2.0 μm, and the standard deviation of the mass content of each element of Ni, Co and Mn in the positive electrode material precursor is all ≦0.05. In step S200, the cathode material precursor and lithium source are mixed, and then sintered in an oxygen-containing atmosphere to obtain a cathode material. The standard deviations of the mass content of each element, Ni, Co, and Mn, in the single-crystal cathode material are all ≤0.03, and the crystal lattice strain of the single-crystal cathode material is ε and ε < 0.2%.

[0092] The present invention provides a method for producing a single-crystal cathode material, which involves atomizing a mixed solution containing a nickel salt, a cobalt salt, and a manganese salt, followed by thermal decomposition to obtain a cathode material precursor. The surface area weighted average diameter of the cathode material precursor is D[3,2] < 2.0 μm, indicating high reaction activity, which is advantageous for improving the reaction efficiency and mass transfer efficiency of the cathode material precursor and lithium source in the subsequent high-temperature sintering process. Furthermore, the standard deviations of the mass content of each element, Ni, Co, and Mn, in the cathode material precursor obtained by the above production method are all ≤ 0.05, indicating high uniformity of the distribution of Ni, Co, and Mn in the cathode material precursor. Moreover, in the single-crystal cathode material produced by subsequently sintering the above cathode material precursor with a lithium source, the standard deviation of the mass content of each element, Ni, Co, and Mn, is... The deviations are all ≤0.03, indicating high uniformity in the distribution of Ni, Co, and Mn elements within the single-crystal cathode material. This is advantageous in reducing defects in the crystal structure of the single-crystal cathode material. Furthermore, the crystal lattice strain of the single-crystal cathode material is low, with ε < 0.2%. This reduces the diffusion energy barrier for lithium ions between microcrystals, improving the Li ion diffusion coefficient. This allows the single-crystal cathode material to exhibit excellent rate characteristics and a low DCR. In addition, the low crystal lattice strain suppresses the occurrence of fine cracks within the single-crystal cathode material, further improving the cycle performance of the single-crystal cathode material.

[0093] In step S100, a mixed solution containing nickel salt, cobalt salt, and manganese salt is subjected to atomization, followed by thermal decomposition to obtain a positive electrode material precursor. The surface area weighted average diameter of the positive electrode material precursor is D[3,2] < 2.0 μm, and the standard deviations of the mass content of each element, Ni, Co, and Mn, in the positive electrode material precursor are all ≤ 0.05.

[0094] Specifically, the surface area weighted average diameter D[3,2] of the positive electrode material precursor may be 1.98 μm, 1.95 μm, 1.8 μm, 1.75 μm, 1.64 μm, 1.5 μm, 1.3 μm, 1.2 μm, 1.1 μm, 0.8 μm, 0.9 μm, or 0.5 μm, and is not limited thereto. Controlling the surface area weighted average diameter D[3,2] of the positive electrode material precursor within the above range is advantageous for increasing the reaction activity of the positive electrode material precursor and improving the reaction efficiency and mass transfer efficiency in the subsequent sintering process of the positive electrode material precursor with the lithium source. The surface area weighted average diameter D[3,2] of the precursor is mainly related to the thermal decomposition temperature, and as the thermal decomposition temperature increases, the surface area weighted average diameter D[3,2] increases and the reaction activity of the precursor decreases.

[0095] The standard deviations of the mass content of each element, Ni, Co, and Mn, in the cathode material precursor may be, but are not limited to, 0.001, 0.005, 0.009, 0.01, 0.013, 0.02, 0.025, 0.03, 0.036, 0.01, 0.044, 0.045, 0.047, or 0.049.

[0096] In some embodiments, the nickel salt comprises at least one of nickel chloride, nickel sulfate, nickel nitrate, nickel carbonate, nickel oxalate, and nickel acetate.

[0097] In some embodiments, the cobalt salt comprises at least one of cobalt chloride, cobalt oxalate, cobalt carbonate, cobalt sulfate, cobalt nitrate, and cobalt acetate.

[0098] In some embodiments, the manganese salt comprises at least one of manganese chloride, manganese carbonate, manganese sulfate, manganese oxalate, manganese nitrate, and manganese acetate.

[0099] In some embodiments, the molar ratio of Ni, Co, and Mn in the mixed solution is (50-98):(0-20):(0-30), and the content of Co and Mn in the mixed solution is not 0. Specifically, the molar ratio of Ni, Co, and Mn in the mixed solution may be, but is not limited to, 50:0.1:0.1, 60:10:30, 65:15:20, 65:5:30, 70:5:25, 70:10:20, 80:5:15, 85:10:5, or 98:1:1.

[0100] In some embodiments, the total metal concentration in the mixed solution is 200 g / L to 500 g / L, specifically 200 g / L, 220 g / L, 260 g / L, 300 g / L, 350 g / L, 400 g / L, 450 g / L, 480 g / L, or 500 g / L, and may, of course, be other values ​​within the above range, but is not limited thereto. The applicant has found that the metal concentration in the mixture can affect the manufacturing efficiency of the precursor and the degree of the thermal decomposition reaction. If the metal concentration in the mixture is too high, the reaction of the precursor may be incomplete, leading not only to structural instability but also to an ideal uniformity in the distribution of particle elements. If the metal concentration in the mixture is too low, not only does the manufacturing efficiency decrease, but when the mixture evaporates rapidly at high temperatures, many hollow spherical particles and fragmentation are likely to occur, resulting in an ideal particle size distribution. Furthermore, many fine particles that affect the performance of the material are generated, along with a relatively small amount of larger particles. These larger particles tend to have an uneven distribution of elements and affect the surface area-weighted average diameter D[3,2] of the single-crystal cathode material precursor.

[0101] In some embodiments, the mixed solution further comprises a dopant containing element N, where N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y.

[0102] In some embodiments, the ultrasonic stirring step is further included before atomization of the mixture, and the ultrasonic stirring includes heating and ultrasonic stirring of the mixture in a reaction vessel having an ultrasonic stirring function.

[0103] In some embodiments, the ultrasonic stirring temperature is 50°C to 70°C.

[0104] In some embodiments, the ultrasonic frequency of the ultrasonic stirring is 30 kHz to 50 kHz, and the ultrasonic stirring time is 0.5 hours to 2 hours.

[0105] By heating and ultrasonic stirring before atomization, the chemical elements in the mixture can be further thoroughly mixed and homogenized, allowing for the rapid acquisition of more uniform atomized droplets. This results in a more uniform distribution of elements on the surface of the precursor particles during thermal decomposition, and a smaller average standard deviation value for mass content.

[0106] In some embodiments, a surfactant is added before atomizing the mixture, and the surfactant includes polyethylene glycol.

[0107] As can be understood, when polyethylene glycol dissolves in water and reaches a certain concentration, it reduces the surface tension of the system, decreases the overall particle size of the cathode material precursor particles, and also makes the elemental distribution more uniform, thereby reducing the surface area weighted average diameter D[3,2] of the single-crystal cathode material precursor.

[0108] In some embodiments, the surfactant constitutes 0.5% to 5% of the total mass of the mixture. Within this range, the surfactant can stably obtain precursor particles that are smooth in shape, uniform, and have excellent dispersibility. If the concentration is too low, the effect of the surfactant is not significantly beneficial, and if it is too high, it not only affects the overall concentration of the mixture but also causes the precipitation of Ni, Co, and Mn metal ions.

[0109] In some embodiments, it further includes an ultrasonic stirring step before the atomization treatment of the mixed solution. The mixed solution is put into a reaction kettle with ultrasonic stirring function and heated to 50°C to 70°C. At the same time, the ultrasonic frequency of ultrasonic stirring is adjusted to 30 - 50KHz. After ultrasonic stirring in the reaction kettle for 0.5h - 2h, the heating function is turned off, and polyethylene glycol with 0.5% - 5% of the total mass of the mixed solution is added, and then ultrasonic stirring is carried out for another 0.5h - 1h. In some embodiments, the chemical general formula of the cathode material precursor is Ni a Co b Mn c N d O e where 0.50 ≦ a ≦ 0.98, 0 < b ≦ 0.20, 0 < c ≦ 0.30, 0 ≦ d ≦ 0.10, a + b + c + d = 1, 1 ≦ e ≦ 1.15, and N contains at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y.

[0110] In some embodiments, the range of the mass content of each element of Ni, Co, and Mn in the cathode material precursor is all ≦ 0.12. Specifically, it may be 0.01, 0.015, 0.018, 0.02, 0.029, 0.03, 0.035, 0.048, 0.059, 0.06, 0.08, 0.097, 0.10, 0.105, 0.11, 0.112, 0.115, or 0.119, etc. Of course, it may also be other values within the above range, and it is not limited here.

[0111] As can be understood, the standard deviation and range of the mass content of each element, Ni, Co, and Mn, in the cathode material can reflect the degree of uniformity of the distribution of Ni, Co, and Mn elements in the cathode material precursor. The lower the standard deviation and range of the mass content of each element, the more uniform the distribution of Ni, Co, and Mn elements in the cathode material precursor. Furthermore, the uniformity of the distribution of Ni, Co, and Mn elements in the cathode material precursor and the uniformity of the distribution of Ni, Co, and Mn elements in the single-crystal cathode material have good inheritance properties. The more uniform the distribution of Ni, Co, and Mn elements in the cathode material precursor, the more uniform the distribution of Ni, Co, and Mn elements in the single-crystal cathode material produced from that cathode material precursor.

[0112] Controlling the standard deviation and range of the mass content of each element, Ni, Co, and Mn, in the cathode material precursor within the above range is advantageous in improving the uniformity of the distribution of Ni, Co, and Mn elements in the single-crystal cathode material. This results in high uniformity of the distribution of Ni, Co, and Mn elements in the single-crystal cathode material, fewer defects in the crystal structure of the single-crystal cathode material, and low crystal lattice distortion.

[0113] In some embodiments, the flow rate of the mixed solution is 100 L / h to 900 L / h, and may be, specifically, 100 L / h, 200 L / h, 300 L / h, 400 L / h, 500 L / h, 600 L / h, 700 L / h, 800 L / h, or 900 L / h, and is not limited thereto. The higher the flow rate of the mixed solution, the faster the synthesis rate of the precursor, but the worse the uniformity of the Ni / Co / Mn distribution. When the flow rate is lower than 100 L / h, the synthesis efficiency of the precursor is low, the manufacturing cost is high, and the flow rate of the mixed solution is higher than 900 L / h, the standard deviation and variance of the mass content of each element, Ni, Co, and Mn, in the precursor increase significantly, the uniformity of the distribution of Ni, Co, and Mn elements in the manufactured single-crystal cathode material decreases, and the crystal lattice distortion increases.

[0114] In some embodiments, the pressure of the atomization process is 0.4 MPa to 0.8 MPa, specifically 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.75 MPa, or 0.8 MPa, and of course, it may be any other value within the above range, and is not limited thereto.

[0115] In some embodiments, the thermal decomposition temperature is 500°C to 850°C, specifically 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C, but is not limited to the listed values, and other unlisted values ​​within that range are also applicable. As the thermal decomposition temperature increases, the surface area weighted average diameter D[3,2] of the cathode material precursor decreases, causing a decrease in precursor activity. When the thermal decomposition temperature is higher than 850°C, the surface area weighted average diameter D[3,2] of the cathode material precursor is greater than 2.0 μm, at which point the reaction activity of the cathode material precursor is poor, resulting in many defects in the subsequently manufactured single-crystal cathode material, a crystal lattice strain ε exceeding 0.2%, and causing the single-crystal cathode material to exhibit low rate characteristics, high DCR, and low cycle performance. Therefore, it is advantageous to appropriately lower the thermal decomposition temperature of the precursor to improve the reaction activity of the precursor and improve the rate and DCR of the cathode material. However, if the thermal decomposition temperature obtained during production is less than 500°C, the decomposition of the metal salts Ni, Co, and Mn is not complete, and the precursor Cl - NO3 - CO3 2- This can lead to excessively high anion content, and in the subsequent manufacturing process of the cathode material, these residual anions suppress the formation of single crystals and corrode the sintering furnace.

[0116] In step S200, the cathode material precursor and lithium source are mixed, and then sintered in an oxygen-containing atmosphere to obtain a cathode material. The standard deviations of the mass content of each element, Ni, Co, and Mn, in the single-crystal cathode material are all ≤0.03, and the crystal lattice strain of the single-crystal cathode material is ε and ε < 0.2%.

[0117] In some embodiments, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium ethaneate, lithium sulfate, lithium chloride, lithium nitrate, and lithium oxalate.

[0118] In some embodiments, the molar ratio of lithium in the lithium source to the sum of nickel, cobalt, and manganese in the cathode material precursor is 0.98 to 1.10, specifically 0.98, 0.99, 1.01, 1.03, 1.05, 1.06, 1.08, 1.09, or 1.10, and is not limited to other values ​​within the above range.

[0119] In some embodiments, the sintering reaction temperature is 750°C to 950°C, specifically 750°C, 760°C, 780°C, 800°C, 850°C, 900°C, 920°C, or 950°C, and is not limited to other values ​​within the above range. The sintering temperature is closely related to the Ni content; the higher the Ni content, the lower the sintering temperature. Furthermore, an appropriate sintering temperature is advantageous in reducing crystal structure defects and decreasing crystal lattice strain, thereby improving the electrochemical performance of the single-crystal cathode material.

[0120] In some embodiments, the sintering reaction time is 10h to 30h, specifically 10h, 12h, 15h, 16h, 18h, 20h, 24h, 28h, or 30h, and of course, it may be any other value within the above range, and is not limited thereto.

[0121] In a fourth embodiment, an embodiment of the present application provides a lithium-ion battery, the lithium-ion battery comprising a cathode material manufactured by the single-crystal cathode material described in the first embodiment or by the method for manufacturing the single-crystal cathode material described in the third embodiment.

[0122] The beneficial effects of this application will be further explained below with reference to examples and comparative examples. (Example 1) (1) Molar ratio (n Ni :nCo :n Mn Nickel chloride, cobalt chloride, and manganese chloride are weighed using a ratio of 0.67:0.05:0.28 and added to water to prepare a mixed solution. The total metal concentration in the mixed solution is controlled to 300 g / L. The mixed solution is placed in a reaction vessel with an ultrasonic stirring function and heated to 60°C. At the same time, the ultrasonic frequency of the ultrasonic stirring is adjusted to 33 kHz. After ultrasonic stirring in the reaction vessel for 1 hour, the heating function is turned off, and 1% of the total mass of the mixed solution is added as polyethylene glycol. Ultrasonic stirring is continued for another 0.5 hours, and the total mass of elements Ni, Co, and Mn is used as the basis for SO4 2- The content was 900 ppm. (2) After atomizing the above mixed solution into droplets, it was placed in an air atmosphere and thermally decomposed in a firing furnace at 650°C, with the flow rate of the mixed solution controlled to 200 L / h and the atomization pressure to 0.6 MPa. (3) The thermal decomposition products are pulverized with airflow to obtain a cathode material precursor (Ni 0.67 Co 0.05 Mn 0.28 O) was obtained. (4) Molar ratio (n Ni+Co+Mn :n Li The cathode material precursor was weighed in a 1:1 ratio and uniformly mixed with lithium carbonate. The mixture was then heated to 920°C in an oxygen atmosphere and sintered for 20 hours to obtain a single-crystal cathode material.

[0123] The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.8 μm, and the better tap density is 1.95 g / cm³. 3 That was the case.

[0124] Figure 1 is an SEM morphological view of the cathode material precursor manufactured in Example 1 of the present application, and Figure 2 is another SEM morphological view of the cathode material precursor manufactured in Example 1 of the present application. As shown in Figures 1 and 2, the cathode material precursor contains secondary particles, and the secondary particles contain aggregated primary particles.

[0125] When the cathode material precursor manufactured in Example 1 of this application was observed with a scanning electron microscope, 10 random points were selected from the cathode material precursor at a magnification of 3K and EDS point scanning was performed to measure the Ni, Co, and Mn content. As shown in Figure 3, the EDS spectrum results of the cathode material precursor showed that the range of Ni content was 0.095 with a standard deviation of 0.036, the range of Co content was 0.029 with a standard deviation of 0.009, and the range of Mn content was 0.081 with a standard deviation of 0.030. This demonstrated high uniformity in the distribution of Ni, Co, and Mn in the cathode material precursor manufactured in Example 1. Furthermore, when detected by ion chromatography, free SO4 was found on the surface of the precursor. 2- The content was 504 ppm.

[0126] Figure 4 shows the Williamsone-Hall analysis fitting curve of the single-crystal cathode material manufactured in Example 1 of this application. As shown in Figure 4, by analyzing the data in Figure 4, it can be calculated that the crystal lattice strain of the single-crystal cathode material is 0.11%. Details of other performance parameters of the cathode material precursor and the single-crystal cathode material are shown in Tables 1 and 2.

[0127] (Example 2) The difference from Example 1 was that (2) after atomizing the above mixed solution into droplets, it was placed in an air atmosphere and thermally decomposed in a firing furnace at 750°C, with the flow rate of the mixed solution controlled to 200 L / h and the atomization pressure to 0.6 MPa. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.7 μm, and the better tap density is 1.85 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0128] (Example 3) The difference from Example 1 was that (2) after atomizing the above mixed solution into droplets, it was placed in an air atmosphere and thermally decomposed in a firing furnace at 650°C, with the flow rate of the mixed solution controlled to 100 L / h and the atomization pressure to 0.6 MPa. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 4.0 μm, and the better tap density is 2.12 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0129] (Example 4) The difference from Example 1 was that (2) after atomizing the above mixed solution into droplets, it was placed in an air atmosphere and thermally decomposed in a firing furnace at 500°C, with the flow rate of the mixed solution controlled to 500 L / h and the atomization pressure to 0.6 MPa. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.8 μm, and the better tap density is 1.90 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0130] (Example 5) The difference from Example 1 is (4) molar ratio (n Ni+Co+Mn :n Li The method involved weighing the cathode material precursor in a 1:1 ratio, uniformly mixing it with lithium carbonate, and then heating it to 950°C in an oxygen atmosphere for 20 hours to obtain a single-crystal cathode material. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50The particle size is 4.5 μm, and the better tap density is 2.2 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0131] (Example 6) The difference from Example 1 is (4) molar ratio (n Ni+Co+Mn :n Li The method involved weighing the cathode material precursor in a 1:1 ratio, uniformly mixing it with lithium carbonate, and then heating it to 950°C in an oxygen atmosphere for 20 hours to obtain a single-crystal cathode material. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.0 μm, and the better tap density is 1.68 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0132] (Example 7) (1) Molar ratio (n Ni :n Co :n Mn Nickel chloride, cobalt chloride, and manganese chloride were weighed using a ratio of 0.88:0.06:0.04 and added to water to prepare a mixed solution. The total metal concentration in the mixed solution was controlled to 300 g / L, and the total mass of elements Ni, Co, and Mn was used as the basis for SO4 2- The content was ≤1780 ppm. (2) After atomizing the above mixed solution into droplets, it was placed in an air atmosphere and thermally decomposed in a firing furnace at 600°C, with the flow rate of the mixed solution controlled to 200 L / h and the atomization pressure to 0.6 MPa. (3) The thermal decomposition products are pulverized with airflow to obtain a cathode material precursor (Ni 0.88 Co 0.06 Mn 0.04 O) was obtained. (4) Molar ratio (n Ni+Co+Mn :n LiThe cathode material precursor was weighed in a 1:1 ratio and uniformly mixed with lithium carbonate. The mixture was then heated to 850°C in an oxygen atmosphere and sintered for 15 hours to obtain a single-crystal cathode material. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.88 Co 0.06 Mn 0.04 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.2 μm, and the better tap density is 1.77 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0133] (Example 8) (1) Molar ratio (n Ni :n Co :n Mn :n Al Nickel chloride, cobalt chloride, manganese chloride, and aluminum chloride were weighed using a ratio of 0.88:0.06:0.03:0.03 and added to water to prepare a mixed solution. The total metal concentration in the mixed solution was controlled to 300 g / L. (2) After atomizing the above mixed solution into droplets, it was placed in an air atmosphere and thermally decomposed in a firing furnace at 600°C, with the flow rate of the mixed solution controlled to 200 L / h and the atomization pressure to 0.6 MPa. (3) The thermal decomposition products are pulverized with airflow to obtain a cathode material precursor (Ni 0.88 Co 0.06 Mn 0.04 Al 0.03 O) was obtained. (4) Molar ratio (n Ni+Co+Mn+Al :n Li The cathode material precursor was weighed in a 1:1 ratio and uniformly mixed with lithium hydroxide. The mixture was then heated to 850°C in an oxygen atmosphere and sintered for 15 hours to obtain the cathode material. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.88 Co 0.06 Mn 0.03 Al 0.03 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.2 μm, and the better tap density is 1.78 g / cm³.3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0134] (Example 9) The difference from Example 1 is that (1) the total mass of elements Ni, Co, and Mn is used as the basis, and SO4 2- The content was 200 ppm. When detected by ion chromatography, free SO4 was found on the surface of the precursor produced in this example. 2- The content was 100 ppm. The single-crystal cathode material produced in this example has the general chemical formula LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.8 μm, and the better tap density is 1.95 g / cm³. 3 The results were as follows. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0135] (Example 10) The difference from Example 1 is (1) molar ratio (n Ni :n Co :n Mn Nickel chloride, cobalt chloride, and manganese chloride are weighed using a ratio of 0.67:0.05:0.28 and added to water to prepare a mixed solution. The total metal concentration in the mixed solution is controlled to 500 g / L, and 5% polyethylene glycol of the total mass of the mixed solution is added. Based on the total mass of elements Ni, Co, and Mn, SO4 is used. 2- The content was 900 ppm. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.8 μm, and the better tap density is 1.83 g / cm³. 3 The results were as follows. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0136] (Example 11) The difference from Example 1 is (1) molar ratio (n Ni :n Co :n Mn Nickel chloride, cobalt chloride, and manganese chloride are weighed using a ratio of 0.67:0.05:0.28 and added to water to prepare a mixed solution. The total metal concentration in the mixed solution is controlled to 200 g / L. The mixed solution is placed in a reaction vessel with an ultrasonic stirring function and heated to 60°C. At the same time, the ultrasonic frequency of the ultrasonic stirring is adjusted to 33 kHz, and ultrasonic stirring is performed in the reaction vessel for 1 hour. The total mass of elements Ni, Co, and Mn is used as the reference for SO4 2- The content was 900 ppm. The single-crystal cathode material manufactured in this embodiment has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 4.1 μm, and the better tap density is 1.82 g / cm³. 3 The results were as follows. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0137] (Comparative Example 1) The difference from Example 1 was that (2) after atomizing the above mixed solution into droplets, it was placed in an air atmosphere and thermally decomposed in a firing furnace at 880°C, with the flow rate of the mixed solution controlled to 200 L / h and the atomization pressure to 0.6 MPa. The single-crystal cathode material produced in this comparative example has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size of the positive electrode material D 50 The particle size is 3.82 μm, and the better tap density is 1.86 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0138] (Comparative Example 2) The difference from Example 1 was that (2) after atomizing the above mixed solution into droplets, it was placed in an air atmosphere and thermally decomposed in a firing furnace at 650°C, with the flow rate of the mixed solution controlled to 1000 L / h and the atomization pressure to 0.6 MPa. The single-crystal cathode material produced in this comparative example has a general chemical formula of LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50 The particle size is 3.72 μm, and the better tap density is 1.90 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0139] (Comparative Example 3) The difference from Example 1 is (4) molar ratio (n Ni+Co+Mn :n Li The method involved weighing the cathode material precursor in a 1:1 ratio, uniformly mixing it with lithium carbonate, and then sintering it in an oxygen atmosphere at 700°C for 20 hours to obtain the cathode material. The cathode material produced in this comparative example is a polycrystalline cathode material, and its general chemical formula is LiNi 0.67 Co 0.05 Mn 0.28 O2, with an average particle size D of the polycrystalline cathode material. 50 The particle size is 3.2 μm, and the better tap density is 1.8 g / cm³. 3 That was the case. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0140] (Comparative Example 4) Refer to Example 2 of CN113488642A for Ni 0.88 Co 0.06 Mn 0.03 Al 0.03 (OH)2 quaternary precursors and corresponding cathode materials were fabricated. (1) Preparation of Solution 1: Nickel:cobalt:manganese hexahydrate, manganese sulfate monohydrate, and cobalt sulfate heptahydrate are weighed in a molar ratio of nickel:cobalt:manganese = 0.88:0.06:0.03, dissolved in deionized water, and a transition metal salt solution with a mass concentration of 2 mol / L is prepared, which is called Solution 1. (2) Preparation of the second solution: Weigh aluminum nitrate nonahydrate and dissolve it in deionized water. Then, add concentrated ammonia water with a mass concentration of 25% dropwise to the aluminum salt solution, stirring constantly. Stop adding concentrated ammonia water when the pH is 8-9. Finally, adjust the volume until the aluminum hydroxide concentration reaches 0.11 mol / L. This is called the second solution. (3) Preparation of quaternary transition metal hydroxide precursor: An aqueous ammonia base solution was pre-added to the reaction vessel, the temperature of the reaction system was controlled to 55°C, and the speed of the stirring paddle was adjusted to 1000 rpm. The first solution was added to the reaction vessel at a rate of 35 L / h using meter pump No. 1, the second solution was added to the reaction vessel at a rate of 20 L / h using meter pump No. 2, aqueous ammonia solution was added using meter pump No. 3 to maintain the concentration of aqueous ammonia in the system at 0.5 mol / L, and a 4 mol / L sodium hydroxide solution was added using meter pump No. 4 to control the pH of the reaction system to 10.0 ± 0.5. The material was continuously added and reacted for 17 hours, and after aging for 10 hours, the final precipitate product was filtered and washed, dried in an oven at 110°C for 12 hours, broken up and sieved, and then Ni 0.88 Co 0.06 Mn 0.03 Al 0.03 (OH)2 hydroxide precursor was obtained. (4) Mix the hydroxide precursor and lithium hydroxide uniformly in a molar ratio of 1:1.05, sinter in an oxygen atmosphere at 500°C for 3 hours, then sinter at 850°C for 15 hours, and after cooling, pulverize the product and sift until the D50 is 12 μm, to obtain a single crystal cathode material LiNi 0.88 Co 0.06 Mn 0.03 Al 0.03 O2 was obtained. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0141] (Comparative Example 5) Refer to CN116230922A for Ni 0.8 Co 0.1 Mn 0.1 (OH)2 precursors and corresponding cathode materials were fabricated. (1) NiSO4, CoSO4, and MnSO4 were mixed in a Ni / Co / Mn molar ratio of 0.8:0.1:0.1 to prepare a solution. (2) Add the above solution to a reactor at 55°C and carry out a coprecipitation reaction for 36 hours using NaOH and NH3·H2O as precipitating and chelating agents, respectively, thereby Ni 0.8 Co 0.1 We obtained the Mn0.1(OH)2 precursor. (3) The precursor was dried at 80°C for 12 hours, and then dried at 110°C for another 12 hours. (4) The precursor and lithium hydroxide were added to a dry high-speed mixer in a molar ratio of 1:1.05 and mixed for 5 minutes. (5) The temperature was raised to 950°C at a heating rate of 2°C / min, held at 950°C for 5 hours, and then allowed to cool naturally to 900°C and held for 5 hours. During the heating and holding period, oxygen gas was continuously flowed at a flow rate of 10 mL / min. After the calcination was completed, it was allowed to cool naturally to room temperature, crushed, and classified to obtain LiNi 0.8 Co 0.1 Mn 0.1 We manufactured a single-crystal cathode material of O2. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0142] (Comparative Example 6) The difference from Example 1 is that (1) the total mass of elements Ni, Co, and Mn is used as the basis, and SO4 2- The content was 2000 ppm.

[0143] SO4 released on the surface of the precursor produced in this embodiment 2- The content was 1200 ppm. The single-crystal cathode material produced in this example has the general chemical formula LiNi 0.67 Co 0.05 Mn 0.28 O2, and the average particle size D of the single-crystal cathode material. 50The particle size is 3.8 μm, and the better tap density is 1.95 g / cm³. 3 The results were as follows. Details of other performance parameters for the cathode material precursor and single-crystal cathode material are shown in Tables 1 and 2.

[0144] Test method: (1) Using an energy-dispersive X-ray spectrometer (EDS) attached to a scanning electron microscope at a magnification of 3K, 10 random points were selected and scanned on the surface of an untreated cathode material precursor or single-crystal cathode material to measure the Ni, Co, and Mn content of the cathode material precursor or single-crystal cathode material. The standard deviation and range of the mass content of each element, Ni, Co, and Mn, were statistically analyzed to characterize the uniformity of the distribution of Ni, Co, and Mn elements. (2) The surface area weighted average diameter D[3,2] of the cathode material precursor was obtained by testing with a Malvern 3000 laser particle size analyzer.

[0145] (3) The crystal lattice strain and grain dimensions of the single-crystal cathode material were calculated from the XRD data using Williamsone-Hall analysis. The specific method is as follows: Measurements were performed using a Nippon Rikagaku X-ray diffractometer, with specific conditions of 0.75 degrees / minute, a step size of 0.02, and continuous scanning between 10 and 90 degrees within the range of 2θ. 4sinθ hkl With β on the horizontal axis, hkl cosθ hkl By plotting the values ​​on the vertical axis and performing linear fitting on the plotted curve, the strain ε and grain size D could be calculated from the slope and intercept. It is important to note that the full width at half maximum β used in the fitting is also important. hkl Therefore, it is necessary to eliminate the influence of the equipment, that is, β hkl =β 総 -β 機器 And of which β 総 This is the half-width value of the actual test, and β 機器 This represents the widening of the full width at half maximum (FWHM) due to the equipment, and this value can be calculated by XRD of a test standard silicon wafer. The β value of the test equipment used in this application is... 機器The value was 0.000103. Additionally, data from seven strong diffraction peaks—(003), (101), (102), (104), (015), (107), and (113)—were selected and fitted to improve the degree of linear fitting and reduce the actual test error.

[0146] β hkl cosθ hkl =kλ / D+4εsinθ hkl That's what I decided.

[0147] Here, β is the full width at half maximum, θ is the diffraction angle, both in radians, k is a constant of 0.89, λ is the X-ray wavelength of 0.154 nm, and D is the grain size in nm. ε is the crystal lattice strain, which is dimensionless.

[0148] (4) Using a BetterTap, a fixed amount of sample was weighed and tested for tap density by vibrating 3000 times at 300 times / min.

[0149] (5) Electrochemical performance test: The electrochemical performance of the materials was evaluated using a buckle-type half-cell, and the specific method is as follows: Single-crystal cathode material, conductive carbon black, and PVDF were weighed in a mass ratio of 93:5:2, and N-methyl-2-pyrrolidone (NMP) was added to a solid content of 50%. A viscous slurry was prepared using a high-speed disperser, uniformly applied to aluminum foil using a scraper, dried in an 80°C oven, and then roll-pressed to cut a cathode sheet with a diameter of 14 mm. A 16 mm lithium sheet was used as the anode sheet, a Celgard polypropylene film as the separator, and a 1 mol / L LiPF6 carbonate ester solution was used as the electrolyte. The assembly was carried out in a glove box filled with argon gas to obtain a buckle-type half-cell. Using the LAND battery test system, capacity and cycle performance tests were performed at 25°C and 3.0~4.3V, and the nominal capacity 1C was set to 200 mAh / g. Additionally, the voltage UA at the initial discharge time and the voltage data UB at 60s, and the discharge current IDis are recorded each week, and the formula for calculating the DC internal resistance is DCR=(UA -U B ) / I Dis That's what I decided.

[0150] (6) SO4 2- Content test: Dissolve 0.5 grams in 50 ml of water, filter with ultrasound for 5 minutes, and then analyze the filtrate using ion chromatography (Thermo Fisher ion chromatography ICS6000 HPIC) to obtain SO4. 2- The ion content was measured.

[0151] (7) Electron backscatter diffraction (EBSD) test: The cathode material sample was first embedded in a carbon-coated (PELCO) graphite block, and then the cross-section of the block was polished using an argon ion beam. Electron backscatter diffraction (EBSD) imaging was performed using a JEOL JSM-7000F scanning electron microscope. The step size of the EBSD graph was set to 250 nm (each pixel being 250 nm × 250 nm). The test results described above are shown in detail in Tables 1 to 3.

[0152] [Table 1]

[0153] [Table 2]

[0154] [Table 3]

[0155] As can be seen from the test data in Tables 1-3, the single-crystal cathode materials manufactured in Examples 1-8 all had a standard deviation of ≤0.03 for the mass content of each element (Ni, Co, and Mn) and a range of ≤0.08 for the mass content of each element (Ni, Co, and Mn). This indicates high uniformity in the distribution of Ni, Co, and Mn elements within the single-crystal cathode material, which is advantageous in reducing crystal structure defects in the single-crystal cathode material. The lattice strain of the single-crystal cathode material was ε < 0.2%, which lowers the diffusion energy barrier for lithium ions between microcrystals and improves the Li ion diffusion coefficient. This allows the single-crystal cathode material to exhibit excellent rate characteristics and a low DCR. Furthermore, the low crystal lattice strain suppresses the occurrence of fine cracks within the single-crystal cathode material, further improving the cycle performance of the single-crystal cathode material.

[0156] As can be seen from the data in Tables 1 and 2, the uniformity of the distribution of Ni, Co, and Mn elements in the cathode material precursor and the uniformity of the distribution of Ni, Co, and Mn elements in the single-crystal cathode material have good inheritance. The smaller the range and standard deviation of the mass content of each type of element (Ni, Co, and M) in the cathode material precursor, the smaller the range and standard deviation of the mass content of each type of element (Ni, Co, and Mn) in the single-crystal cathode material. Furthermore, the range and standard deviation of the Ni, Co, and Mn content in the single-crystal cathode material are always smaller than those of the precursor. This is because high-temperature sintering is required in the manufacturing process of the single-crystal cathode material, which further diffuses metal ions and thereby improves the uniformity of the distribution of Ni, Co, and Mn elements.

[0157] As can be seen from the test data in Tables 1-3, the single-crystal cathode material manufactured in Example 1 showed the best overall performance.

[0158] Comparing Example 1 and Example 2, the single-crystal cathode material of Example 1 exhibited good rate characteristics, low resistance, and high cycle performance. This was because, when manufacturing the cathode material precursor in Example 1, the temperature at which the mixed solution underwent thermal decomposition after atomization was appropriate, the surface area-weighted average diameter D[3,2] of the cathode material precursor was low, the reaction activity of the cathode material precursor was high, the crystal structure defects of the single-crystal cathode material were reduced, and the crystal lattice distortion of the single-crystal cathode material was low. Therefore, the single-crystal cathode material manufactured in Example 1 exhibited better rate characteristics, lower resistance, and better cycle performance.

[0159] Compared to Example 1, in Example 5, the sintering temperature increased during the sintering process of the cathode material precursor and lithium source, resulting in a lower range and standard deviation of the mass content of each element (Ni, Co, and Mn) in the single-crystal cathode material, a decrease in the crystal lattice strain ε of the single-crystal cathode material, and thus improved cycle performance. However, because the crystal grain size of the single-crystal cathode material was significantly larger and the diffusion path of Li ions was longer, the rate characteristics of the single-crystal cathode material produced in Example 5 were worse than those of Example 1.

[0160] Compared to Example 1, in Example 6, the sintering temperature decreased during the sintering process of the cathode material precursor and lithium source, resulting in smaller crystal grain dimensions for the single-crystal cathode material and an increased crystal lattice strain ε. Consequently, the cycle stability of the single-crystal cathode material in Example 6 was lower than that of Example 1.

[0161] Compared to Example 1, Example 9 shows a greater amount of free SO4 in the precursor and cathode materials. 2- The reduced content resulted in better rate and cycle performance.

[0162] Compared to Example 1, Example 10 did not perform ultrasonic stirring before the single-crystal cathode material precursor mixture was atomized, resulting in a higher range and standard deviation of mass content of each element (Ni, Co, and Mn) in the single-crystal cathode precursor, which affected its cycle and internal resistance.

[0163] Compared to Example 1, Example 11, without adding polyethylene glycol and performing ultrasonic stirring before the single-crystal cathode material precursor mixture was atomized, had a larger surface area weighted average diameter D[3,2] of the single-crystal cathode material, which made it possible for large particles to aggregate. Furthermore, the range and standard deviation of the mass content of each element, Ni, Co, and Mn, in the single-crystal cathode precursor was higher, which affected its cycle and internal resistance.

[0164] Compared to Example 1, the liberated SO4 in the cathode material of Comparative Example 6 2- It exceeded 1000 ppm. SO4 2- When the amount became excessive, the material's capacity, rate, and cycle characteristics decreased.

[0165] Compared to Example 1, Comparative Example 1 increased the thermal decomposition temperature during the manufacturing process of the cathode material precursor, thereby increasing the weighted average surface area diameter D[3,2] of the cathode material precursor to more than 2.0 μm. This resulted in poor reaction activity of the cathode material precursor, a high number of defects in the subsequently manufactured single-crystal cathode material, and a crystal lattice strain ε exceeding 0.2%. The single-crystal cathode material exhibited low rate characteristics, high DCR, and low cycle performance.

[0166] Compared to Example 1, the cathode material of Comparative Example 2 showed an increased atomization flow rate during the precursor manufacturing process, resulting in a significant increase in the standard deviation and variance of the mass content of each element, Ni, Co, and Mn, in the manufactured cathode material precursor. This led to a decrease in the uniformity of the distribution of Ni, Co, and Mn elements in the manufactured single-crystal cathode material, an increase in crystal lattice strain, and a crystal lattice strain ε exceeding 0.2%. Consequently, both the rate characteristics and cycle performance of the single-crystal cathode material manufactured in Comparative Example 2 were reduced.

[0167] Compared to Example 1, the cathode material of Comparative Example 3 had a sintering temperature that was too low during the sintering process of the precursor and lithium source, resulting in a polycrystalline cathode material. The crystal grain size of this cathode material was lower than 150 nm, and it had good rate characteristics, but the crystal lattice strain exceeded 0.2%, making it prone to cracking and pulverization during cycling, which reduced the structural stability of the cathode material and significantly decreased its cycle capacity.

[0168] Compared with Example 1, the standard deviation and dispersion of the mass contents of various elements of Ni, Co, and Mn in the cathode material precursor of Comparative Example 4 are significantly larger than those of Example 1. Therefore, the crystal lattice strain of the obtained single-crystal cathode material is significantly increased, and the crystal lattice strain exceeds 0.2%, thereby significantly degrading the rate performance and cycle performance of the single-crystal cathode material.

[0169] Similarly, the single-crystal cathode material produced in Comparative Example 5 has an overly large surface area weighted average diameter D[3,2] of the cathode material precursor, and the standard deviation and dispersion of the mass contents of various elements of Ni, Co, and Mn in the cathode material precursor are significantly larger than those of Example 1. Therefore, the crystal lattice strain of the produced single-crystal cathode material is significantly increased, and the crystal lattice strain exceeds 0.2%, thereby significantly degrading the rate performance and cycle performance of the cathode material.

[0170] The above are only preferred embodiments of the present application and do not limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present application should all be included within the protection scope of the present application.

[0171] [Cross-reference to related applications] This application claims the priority of a Chinese patent application with an application number of "202311331910.3" and an application title of "Cathode Material Precursor, Single-Crystal Cathode Material and Manufacturing Method, Lithium-Ion Battery", which was filed with the Chinese Patent Office on October 13, 2023, and all its contents are incorporated herein by reference.

Claims

1. A single-crystal cathode material, wherein the general chemical formula of the single-crystal cathode material is Li ｘ Ni ａ Co ｂ Mn ｃ N ｄ O ２ Here, 0.98 ≤ x ≤ 1.1, 0.50 ≤ a ≤ 0.98, 0 < b ≤ 0.20, 0 < c ≤ 0.30, 0 ≤ d ≤ 0.10, a + b + c + d = 1, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn and Y. When the single-crystal cathode material is observed with a scanning electron microscope, 10 points are randomly selected from the single-crystal cathode material at a magnification of 3K and EDS point scanning is performed to measure the Ni, Co, and Mn content. In the EDS spectral results of the single-crystal cathode material, the standard deviations of the mass content of each element, Ni, Co, and Mn, in the single-crystal cathode material are all ≤0.

03. The single-crystal cathode material is characterized in that the crystal lattice strain of the single-crystal cathode material is ε and ε < 0.2%.

2. The single-crystal cathode material contains SO ４ ２－ and the content of the SO ４ ２－ is δ, where 0 ppm ≤ δ ≤ 800 ppm. The single-crystal cathode material according to claim 1, characterized in that.

3. The single-crystal cathode material according to claim 1, wherein the single-crystal cathode material comprises at least one single crystal grain having the same orientation, and the average particle size of the single crystal grain is 1 μm to 5 μm.

4. The single-crystal cathode material according to claim 1, characterized in that the mass content range of each element, Ni, Co, and Mn, in the single-crystal cathode material is all ≤0.

08.

5. The single-crystal cathode material according to claim 1, further comprising a coating layer, wherein the coating layer comprises a metal oxide or a lithium ion conductor, wherein the metal in the metal oxide comprises at least one of Al, Ti, Zr, Y, Nb, Mg, W, B, Ce, Co, and Mn.

6. The aforementioned single-crystal cathode material is (1) The dimensions of the crystal grains of the single-crystal cathode material are D, and the characteristics are that 150 nm < D < 250 nm. (2) The average particle size D of the single-crystal cathode material ５０ It has the characteristic of being 1.5 μm to 5 μm in size. (3) The better tap density of the single-crystal cathode material is >1.5 g / cm³ ３ A single-crystal cathode material according to any one of claims 1 to 5, characterized in that it satisfies at least one of the following characteristics.

7. The aforementioned single-crystal cathode material is (1) The average particle size D of the single-crystal cathode material ５０ It has the characteristic of being 3.0 to 4.5 μm in size. (2) The compaction density of the single-crystal cathode material is 1.68 to 2.2 g / cm³. ３ The characteristic of being (3) The general chemical formula of the single-crystal cathode material is LiNi ０．６７ Co ０．０５ Mn ０．２８ O ２ LiNi ０．８８ Co ０．０６ Mn ０．０４ O ２ Or LiNi ０．８８ Co ０．０６ Mn ０．０３ Al ０．０３ O ２ The single-crystal cathode material according to claim 6, characterized in that it contains at least one of the features of including at least one of the following.

8. A cathode material precursor, wherein the general chemical formula of the cathode material precursor is Ni ａ Co ｂ Mn ｃ N ｄ O ｅ Here, 0.50 ≤ a ≤ 0.98, 0 < b ≤ 0.20, 0 < c ≤ 0.30, 0 ≤ d ≤ 0.10, a + b + c + d = 1, 1 ≤ e ≤ 1.15, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn and Y. A positive electrode material precursor characterized in that the weighted average diameter of the surface area of ​​the positive electrode material precursor is D[3,2] < 2.0 μm, and the standard deviations of the mass content of each element, Ni, Co, and Mn, in the positive electrode material precursor are all ≤ 0.

05.

9. The cathode material precursor is SO ４ ２－ Including the SO ４ ２－ The cathode material precursor according to claim 8, characterized in that the content of is η, where 0 ppm ≤ η ≤ 1800 ppm.

10. The positive electrode material precursor according to claim 8, characterized in that the range of mass content of each element, Ni, Co, and Mn, in the positive electrode material precursor is all ≤0.

12.

11. The aforementioned cathode material precursor is (1) The positive electrode material precursor has the technical characteristic of containing secondary particles, and the secondary particles contain a plurality of aggregated primary particles. (2) The positive electrode material precursor contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, and the primary particles have the technical characteristic of being spherical. (3) The cathode material precursor according to claim 8, characterized in that the cathode material precursor satisfies at least one of the following technical features: the cathode material precursor comprises secondary particles, the secondary particles comprise a plurality of aggregated primary particles, and the particle size of the primary particles is 20 nm to 1000 nm.

12. The aforementioned cathode material precursor is (1) The average particle size D of the positive electrode material precursor ５０ It has the technical characteristic of being <3.5 μm. (2) The specific surface area of ​​the cathode material precursor is >5 m² ２ The technical characteristic is that it is / g. (3) The better tap density of the cathode material precursor is >1 g / cm³ ３ The cathode material precursor according to claim 8, characterized in that it satisfies at least one of the technical features of being

13. A method for manufacturing a single-crystal cathode material, The process involves atomizing a mixed solution containing nickel salt, cobalt salt, and manganese salt, followed by thermal decomposition to obtain a positive electrode material precursor, wherein the surface area weighted average diameter of the positive electrode material precursor is D[3,2] < 2.0 μm, and the standard deviations of the mass content of each element Ni, Co, and Mn in the positive electrode material precursor are all ≤ 0.

05. A method for producing a single-crystal cathode material, comprising the steps of: mixing the cathode material precursor with a lithium source, sintering in an oxygen-containing atmosphere to obtain a single-crystal cathode material; wherein the standard deviations of the mass content of each element Ni, Co, and Mn in the single-crystal cathode material are all ≤0.03, and the crystal lattice strain of the single-crystal cathode material is ε and ε < 0.2%.

14. (1) The molar ratio of Ni, Co, and Mn in the mixed solution is (50-98):(0-20):(0-30), and the content of Co and Mn in the mixed solution is not 0. (2) The total metal concentration in the mixed solution is 200 g / L to 500 g / L. (3) The mixed solution further contains an N-containing dopant, wherein N contains at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y. (4) The general chemical formula of the cathode material precursor is Ni ａ Co ｂ Mn ｃ N ｄ O ｅ Here, 0.50 ≤ a ≤ 0.98, 0 < b ≤ 0.20, 0 < c ≤ 0.30, 0 ≤ d ≤ 0.10, a + b + c + d = 1, 1 ≤ e ≤ 1.15, and N has the characteristic of containing at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y. (5) The flow rate of the mixed solution is 100 L / h to 900 L / h. (6) The pressure of the atomization treatment is characterized by being 0.4 MPa to 0.8 MPa. The manufacturing method according to 13, characterized in that it includes at least one of the following features: (7) the temperature of the thermal decomposition is 500°C to 850°C.

15. A lithium-ion battery, characterized in that the lithium-ion battery includes a single-crystal cathode material described in any one of claims 1 to 12 or a single-crystal cathode material manufactured by a method for manufacturing a single-crystal cathode material described in any one of claims 13 or 14.

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