Lithium-containing oxide precursor, preparation method, positive electrode material, and secondary battery

Abstract

The application discloses a lithium-containing oxide precursor, a preparation method, a positive electrode material and a secondary battery, wherein the lithium-containing oxide precursor has a powder rate of less than or equal to 20%, and the powder rate refers to the number ratio of secondary particles with a particle size of less than or equal to 1 micrometer. The lithium-containing oxide precursor has a low powder rate, which is beneficial to improving the cycle stability of the positive electrode material. The lithium-containing oxide precursor is sintered to prepare the positive electrode material, and no or only a small amount of lithium carbonate is needed, so that the lithium mixing process can be simplified, the distribution of lithium elements is more uniform, the loading capacity is improved, and the sintering cost of the positive electrode end is reduced.

Description

Technical Field

[0001] This invention relates to the field of cathode material precursor technology, and more specifically, to lithium oxide precursors, preparation methods, cathode materials, and secondary batteries. Background Technology

[0002] With the rapid development of electric vehicles and energy storage systems, the energy density and cycle life of lithium-ion batteries are facing increasingly stringent challenges. As the core component of lithium batteries, the composition, morphology, and elemental distribution of the cathode material's precursor directly determine the electrochemical performance of the final product. Traditional cathode material preparation often employs a co-precipitation method combined with a post-mixing lithium process: first, nickel, cobalt, and manganese hydroxide or oxide precursors are prepared through co-precipitation, then mixed with a lithium source using mechanical methods such as high-energy ball milling, followed by high-temperature sintering. However, this process route has two fundamental contradictions: first, the precipitation conditions of nickel, cobalt, and manganese during co-precipitation are difficult to simultaneously accommodate the solubility characteristics of lithium ions, preventing lithium from participating in precipitation during the precursor formation stage, necessitating the introduction of lithium through post-mixing; second, post-mixing mechanical mixing cannot achieve atomically uniform distribution of lithium within the particles, easily leading to localized lithium excess or deficiency, causing problems such as cation mixing and structural collapse, severely affecting the material's rate performance and cycle stability.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a lithium oxide precursor, a preparation method, a cathode material, and a secondary battery. The lithium oxide precursor with low micron powder content is beneficial for obtaining a cathode material with low micron powder content and less agglomeration, and it is also beneficial for increasing the packing weight.

[0005] This invention is implemented as follows: In a first aspect, the present invention provides a lithium oxide precursor, wherein the micronization rate of the lithium oxide precursor is ≤20%, and the micronization rate refers to the percentage of secondary particles with a particle size of less than or equal to 1 μm.

[0006] In an optional embodiment, the lithium oxide precursor satisfies one or more of the following conditions; ① The specific surface area of ​​the lithium oxide precursor is 10-30 m². 2 / g; preferably, the specific surface area is 15-25 m². 2 / g; ② The surface density of the lithium oxide precursor is 10-25%; ③ The sphericity of the secondary particles in the lithium oxide precursor is ≥80%; ④ The tap density of the lithium oxide precursor is 1.0-1.5 g / cm³. 3 ; ⑤ The D50 of the lithium oxide precursor is 3-15 μm; ⑥ The lithium oxide precursor includes secondary particles formed by the aggregation of primary particles, wherein the primary particles are nanoparticles.

[0007] In an optional embodiment, the chemical formula of the lithium oxide precursor is Li. x Ni a Co b Mn c Me d O 1+0.5x Where 0.6≤x≤1.05, 0<a<1, 0≤b<1, 0≤c<1, a+b+c+d =1, and Me is selected from at least one of Na, K, Ca, Sr, Y, Ti, Zr, Nb, Sb, Fe, Cu, Zn, B, and W.

[0008] In an optional embodiment, the lithium oxide precursor has diffraction peaks at 18.0°~22.0°, 36.0°~40.0°, 42.0°~46.0°, and 62.0°~66.0° in a powder X-ray diffraction pattern using Cu-Kα rays.

[0009] In a second aspect, the present invention provides a method for preparing the lithium oxide precursor described in the first aspect, wherein a mixed salt solution including metal elements is subjected to spray pyrolysis to obtain the lithium oxide precursor, wherein the metal ions include nickel and lithium; preferably, all metal elements also include at least one of manganese and cobalt.

[0010] In an optional embodiment, the preparation method satisfies one or more of the following conditions; A. The nickel and lithium elements exist in the mixed salt solution in the form of nitrates; B. The manganese or cobalt element exists in the mixed salt solution in the form of nitrate; C. The total concentration of metal elements in the mixed salt solution is 110~190g / L; D. The mixed salt solution further includes at least one of Na, K, Ca, Sr, Y, Ti, Zr, Nb, Sb, Fe, Cu, Zn, B, and W; E. The ratio of the amount of lithium ions in the mixed salt solution to the sum of the amounts of other metal elements is ≤1.

[0011] In an optional embodiment, the spray pyrolysis temperature is 600-780°C; And / or, the spray pyrolysis pressure is 0.2-0.4 MPa, the feed rate is 2-10 L / h, and the carrier gas flow rate is 30-50 L / min; And / or, the spray pyrolysis is performed using a two-fluid spray gun.

[0012] Thirdly, the present invention provides a cathode material obtained by sintering a material comprising the lithium oxide precursor described in the first aspect or the lithium oxide precursor prepared by the preparation method described in the second aspect.

[0013] In an optional embodiment, the sintering includes a first-stage sintering and a second-stage sintering, wherein the first-stage sintering temperature is 700-800℃ and the time is 1.5-2.5h; the second-stage sintering temperature is 950-1000℃ and the time is 10-14h. And / or, the sintering includes a first-stage sintering and a second-stage sintering, wherein the heating rate of the first-stage sintering and the second-stage sintering is 4-6℃ / min; And / or, the sintering atmosphere includes oxygen and an inert gas, wherein the volume fraction of oxygen is 20-21%; And / or, the material may also include lithium carbonate.

[0014] Fourthly, the present invention provides a secondary battery comprising the positive electrode material described in the foregoing embodiments.

[0015] The present invention has the following beneficial effects: The lithium oxide precursor in this application has a low micronization rate, which helps to reduce the micronization in the single crystal cathode material prepared from it, thereby significantly improving the cycle stability of the cathode material. The cathode material prepared by sintering the lithium oxide precursor in this application does not require or only requires a small amount of lithium carbonate mixing, which simplifies the lithium mixing process, makes the lithium element distribution more uniform, increases the amount of material packed, and reduces the sintering cost of the cathode end. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 SEM image (1.00K) of the lithium oxide precursor prepared in Example 1. Figure 2 SEM image (10.0K) of the lithium oxide precursor prepared in Example 1. Figure 3 The image shows the XRD pattern of the lithium oxide precursor prepared in Example 1. Figure 4 SEM image of the cathode material prepared in Example 1; Figure 5 SEM image of the lithium oxide precursor prepared in Comparative Example 1; Figure 6 The image shows the SEM image of the cathode material prepared in Comparative Example 1. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0019] This invention provides a lithium oxide precursor, wherein the micronization rate of the lithium oxide precursor is ≤20%, for example, any number or value between 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 20%, or less than 20%, and the micronization rate refers to the percentage of secondary particles with a particle size of less than or equal to 1 μm.

[0020] The lithium oxide precursor in this application has a low micronization rate, which helps to reduce the amount of micronized powder in the single-crystal cathode material prepared from it, thereby significantly improving the cycle stability of the cathode material. Sintering the lithium oxide precursor of this application to prepare the cathode material eliminates the need for or requires only a small amount of lithium carbonate mixing, simplifying the lithium mixing process, resulting in a more uniform lithium distribution, increasing the amount of material packed, and reducing the sintering cost at the cathode end.

[0021] In an optional embodiment, the specific surface area of ​​the lithium oxide precursor is 10-30 m². 2 / g, for example 10 m² / g, 12 m² / g, 15 m² / g, 18 m² / g, 20 m² / g, 22 m² / g, 25 m² / g, 27 m² / g, 29 m² / g, 30 m² / g; preferably, the specific surface area is 15-25 m² / g. 2 / g. Lithium oxide precursors have a large specific surface area, which is beneficial for sintering to obtain single-crystal cathode materials with less agglomeration. At the same time, the prepared cathode materials have a large specific surface area. Cathode materials with large specific surface area and less agglomeration can provide more electrochemical reaction sites and obtain higher specific capacity. In addition, lithium oxide precursors with large specific surface area can also improve sintering efficiency, so that single-crystal cathode materials can be obtained without gas crushing of the precursor.

[0022] In an optional embodiment, the surface density of the lithium oxide precursor is 10-25%, for example 10%, 12%, 14%, 16%, 18%, 20%, 22%, 23%, 24%, 25%; during spray pyrolysis, a moderately dense shell is formed, which can suppress excessive hollowing or structural collapse caused by the escape of internal gas during high-temperature pyrolysis, thereby maintaining the integrity of the spherical morphology and mechanical stability.

[0023] In an optional embodiment, the sphericity of the secondary particles in the lithium oxide precursor is ≥80%, for example, 80%, 82%, 85%, 88%, 90%, 92%, 94%, 96%, 97%, or 98%. Higher sphericity ensures excellent particle flowability and tap density, which can improve the volumetric energy density of the battery.

[0024] In an optional embodiment, the tap density of the lithium oxide precursor is 1.0-1.5 g / cm³. 3 For example, 1.0 g / cm³, 1.1 g / cm³, 1.2 g / cm³, 1.3 g / cm³, 1.4 g / cm³, 1.45 g / cm³, 1.48 g / cm³, 1.49 g / cm³, and 1.5 g / cm³ are beneficial for increasing the amount of material that can be packed into the pot.

[0025] In an optional embodiment, the D50 of the lithium oxide precursor is 3-15 μm, preferably 7-11 μm, such as 3 μm, 4 μm, 6 μm, 8 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm; which is beneficial for obtaining cathode materials with the target particle size.

[0026] In an optional embodiment, the lithium oxide precursor includes secondary particles formed by the aggregation of primary particles, wherein the primary particles are nanoparticles. These nanoparticles enable the precursor to be sintered into a single-crystal cathode material without gas fragmentation, improving the agglomeration of the single-crystal cathode material, enhancing dispersibility, thereby shortening the lithium-ion diffusion path and improving rate performance. High sphericity ensures excellent particle flowability and tap density, which can improve the volumetric energy density of the battery.

[0027] In an optional embodiment, the chemical formula of the lithium oxide precursor is Li. x Ni a Co b Mn c Me d O 1+0.5xWhere 0.6≤x≤1.05, 0<a<1, 0≤b<1, 0≤c<1, a+b+c+d =1, and Me is selected from at least one of Na, K, Ca, Sr, Y, Ti, Zr, Nb, Sb, Fe, Cu, Zn, B, and W.

[0028] In an optional implementation, x can be any value from 0.6, 0.7, 0.8, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, or 1.05, or a value between any of the above values.

[0029] In an optional implementation, a can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or any number less than 1, or a value between any of these values.

[0030] In an optional implementation, b can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or any number less than 1, or a value between any of these values.

[0031] In an optional implementation, c can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or any number less than 1, or a value between any of these values.

[0032] In an optional embodiment, the lithium oxide precursor has diffraction peaks at 18.0~22.0, 36.0~40.0, 42.0~46.0, and 62.0~66.0 in a powder X-ray diffraction pattern obtained by using Cu-Kα rays.

[0033] The present invention also provides a method for preparing the lithium oxide precursor described in the foregoing embodiments, wherein a mixed salt solution containing metal elements is subjected to spray pyrolysis to obtain the lithium oxide precursor, wherein the metal ions include nickel and lithium; preferably, all metal elements also include at least one of manganese and cobalt, and more preferably, all metal elements also include at least one of Na, K, Ca, Sr, Y, Ti, Zr, Nb, Sb, Fe, Cu, Zn, B and W.

[0034] Spray pyrolysis has the advantages of high efficiency, short process and good environmental protection. It can instantly complete the drying and pyrolysis processes, and obtain the precursor powder from the mixed salt solution in one step. After the lithium oxide precursor powder is sintered into the positive electrode material, it has excellent comprehensive performance in terms of capacity, first efficiency, rate and cycle life.

[0035] In this application, a mixed salt solution is used as a raw material for spray pyrolysis. The components in the mixed salt solution are mixed at the atomic level, which is beneficial to the uniform distribution of lithium in the lithium oxide precursor. The uniform lithium distribution can improve the diffusion rate of lithium ions in the material, reduce the obstacles to ion migration, and improve rate performance and cycle performance.

[0036] In an optional embodiment, the nickel and lithium elements are present in the mixed salt solution in the form of nitrates.

[0037] In an optional embodiment, the manganese or cobalt element is present in the mixed salt solution in the form of nitrate.

[0038] The nickel, cobalt, manganese, and lithium ions are added to the mixed salt solution in the form of nitrates. Nitrates have high water solubility and thermal decomposition activity, which can achieve uniform mixing and synchronous decomposition of each metal component at the molecular scale during spray pyrolysis, ensuring the uniformity of the precursor chemical composition and the uniform distribution of lithium.

[0039] In an optional embodiment, the total concentration of metal ions in the mixed salt solution is 110-190 g / L, preferably 140-180 g / L, for example 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 185 g / L, 188 g / L, or 190 g / L.

[0040] In an optional embodiment, the mixed salt solution further includes at least one of Na, K, Ca, Sr, Y, Ti, Zr, Nb, Sb, Fe, Cu, Zn, B, and W.

[0041] In an optional embodiment, the ratio of the amount of lithium ions in the mixed salt solution to the sum of the amounts of other metal elements is ≤1, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, 0.97, 0.99, or 1.0; to prevent excess lithium from forming a low-melting-point residual phase during the pyrolysis stage and thus damaging the integrity of the primary particle morphology.

[0042] In an optional embodiment, the spray pyrolysis temperature is 600-780℃, for example 600℃, 650℃, 680℃, 700℃, 750℃, 780℃; this ensures that the nitrate solution droplets complete sufficient dehydration, decomposition, and preliminary oxidation during the falling process to form a lithium oxide precursor, avoiding incomplete pyrolysis and residual nitrate ions due to excessively low temperatures, or lithium volatilization and abnormal grain growth due to excessively high temperatures.

[0043] In an optional embodiment, the spray pyrolysis pressure is 0.2-0.4 MPa, for example 0.20 MPa, 0.22 MPa, 0.24 MPa, 0.26 MPa, 0.27 MPa, 0.28 MPa, 0.29 MPa, 0.295 MPa, 0.30 MPa, 0.32 MPa, 0.34 MPa, 0.36 MPa, 0.38 MPa, or 0.40 MPa; the feed rate is 2-10 L / h, for example 2 L / h, 3 L / h, 4 L / h, 5 L / h, 6 L / h, 7 L / h, 8 L / h, 9 L / h, or 10 L / h; and the carrier gas flow rate is 30-50 L / min, for example 30 L / min, 35 L / min, 40 L / min, 45 L / min, or 50 L / min. By limiting the spray pyrolysis pressure, feed rate, and carrier gas flow rate, the droplet atomization particle size, pyrolysis residence time, and heat and mass transfer rate are controlled, so that the droplets can be uniformly heated and pyrolyzed in the furnace, ensuring that the secondary particles have high sphericity, low micronization rate, and moderate surface density.

[0044] In an optional embodiment, the spray pyrolysis is performed using a two-fluid spray gun, which utilizes the shearing action of compressed gas and liquid to achieve stable and controllable atomization, generating micron-sized droplets with narrow particle size distribution and good monodispersity. This is beneficial for obtaining lithium oxide precursors with uniform morphology, high sphericity, and concentrated particle size.

[0045] The present invention also provides a cathode material, which is obtained by sintering a material comprising a lithium oxide precursor as described in any one of the foregoing embodiments or a lithium oxide precursor prepared by any one of the foregoing embodiments.

[0046] The prepared cathode material can inherit the atomic-level uniform distribution characteristics of lithium and transition metals in the precursor, so that the sintered cathode material has high layered structure integrity, less cation mixing, and uniform lithium distribution.

[0047] In an optional embodiment, the sintering includes a first-stage sintering and a second-stage sintering. The first-stage sintering temperature is 700-800℃, for example, 700℃, 710℃, 725℃, 740℃, 760℃, 775℃, 785℃, 790℃, 795℃, or 800℃, and the sintering time is 1.5-2.5 hours, for example, 1.5 hours, 1.6 hours, 1.8 hours, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.45 hours, or 2.5 hours. The second-stage sintering temperature is 950-1000℃, for example, 950℃, 955℃, 960℃, 970℃, 980℃, 985℃, 990℃, 995℃, 998℃, or 1000℃, and the sintering time is 10-14 hours, for example, 10 hours, 10.5 hours, 11 hours, or 11.5 hours. h, 12 h, 12.5 h, 13 h, 13.5 h, 13.8 h, 14 h; the first stage of sintering completes the removal of organic residues, the initial rearrangement of low-valence metal oxides and the formation of crystal nuclei; the second stage of sintering drives the full growth of crystals and the ordering of layered structures, ensuring a high degree of single crystallization, less agglomeration and stable electrochemical reaction interface.

[0048] In an optional embodiment, the sintering includes a first-stage sintering and a second-stage sintering, with the heating rate of the first-stage and second-stage sintering being 4-6℃ / min, for example 4℃ / min, 4.3℃ / min, 4.7℃ / min, 5.0℃ / min, 5.3℃ / min, 5.6℃ / min, 5.8℃ / min, 5.9℃ / min, 5.95℃ / min, and 6℃ / min. This can avoid excessively rapid heating that could lead to excessive temperature differences between the inside and outside of the particles, resulting in cracking or structural stress accumulation, maintaining morphological integrity, reducing breakage and micro-powder generation, while also considering efficiency.

[0049] In an optional embodiment, the sintering atmosphere includes oxygen and an inert gas, wherein the volume fraction of oxygen is 20-21%, for example 20.0%, 20.1%, 20.2%, 20.3%, 20.4%, 20.5%, 20.6%, 20.7%, 20.8%, or 21%; this is beneficial for the full oxidation of transition metals, promotes the stable construction of the layered oxygen framework, and inhibits the formation of cation vacancies or oxygen deficiencies under a reducing atmosphere.

[0050] In an optional embodiment, the material further includes lithium carbonate. In the case where the lithium content in the lithium oxide precursor is slightly lower than the stoichiometry (i.e., x≤1.05), the lithium source is supplemented to ensure the lithium stoichiometry of the final product. At the same time, the slow decomposition characteristics of lithium carbonate at high temperature are utilized to assist the redistribution of lithium in the crystal lattice and defect repair.

[0051] The present invention also provides a secondary battery comprising the positive electrode material described in the foregoing embodiments.

[0052] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0053] Example 1: This embodiment provides a method for preparing a lithium oxide precursor, which specifically includes the following steps: 1. According to the molar percentage of each metal element Ni:Co:Mn = 60:10:30 (mol%), nickel nitrate, cobalt nitrate, manganese nitrate and lithium nitrate are added to pure water in sequence, and the remainder is made up with pure water. Stir to make it fully dissolved to obtain a nitrate solution with a metal ion concentration of 150 g / L (Ni+Co+Mn), where nLi / n(Ni+Co+Mn) = 0.95.

[0054] 2. The nitrate solution obtained in step 1 is fed into a tank and dispersed into atomized droplets at a feed rate of 3 L / h through a two-fluid atomizer with an atomization pressure of 0.25 MPa. The carrier gas flow rate is 35 L / min. The atomized droplets are fed into a spray pyrolysis furnace for pyrolysis to obtain the desired oxide powder. The pyrolysis temperature is 680℃. The pyrolyzed powder product and vapor are separated and recovered using a bag filter.

[0055] Li prepared in Example 1 0.95 Ni 0.60 Co 0.10 Mn 0.30 O 1.48 Scanning electron microscopy of precursor materials, such as Figure 1 , 2 As shown, XRD is as follows Figure 3 As shown, the precursor material has a sphericity of up to 85.5% and a micronization rate of 11%.

[0056] The cathode material was prepared using the lithium-ion cathode material precursor prepared in Example 1. The preparation method was as follows: the precursor and lithium carbonate were weighed out at a molar ratio of lithium / transition metal = 1.05:1, mixed, and then fed into a high-speed mixer. The mixture was mixed at 750 rpm for 0.5 h. The uniformly mixed material was placed in a sagger and spread evenly in a box furnace for sintering. The air flow rate was 20 L / min, and the oxygen content was 20-21%. The temperature of the box furnace was set at 750 °C for the first stage and maintained for 2 h; the temperature was set at 970 °C for the second stage and maintained for 12 h. The heating rate for each stage was 5 °C / min. After sintering, the material was cooled to room temperature in the furnace, crushed, and sieved through a 400-mesh sieve to obtain the cathode material.

[0057] SEM images of the obtained cathode material are shown below. Figure 4 As shown, the cathode material is a single crystal with a rounded shape, a smooth and continuous surface, and no sharp edges or irregular protrusions. This is beneficial for improving the tap density and flowability of the material, while reducing particle scratches and stress concentration during the electrode preparation process, thereby improving the uniformity of slurry dispersion and the coating quality of the electrode sheet.

[0058] Example 2: This embodiment provides a method for preparing a lithium oxide precursor, which specifically includes the following steps: I. According to the molar percentage of each metal element Ni:Co:Mn = 62:7:31 (mol%), nickel nitrate, cobalt nitrate, manganese nitrate and lithium nitrate are added to pure water in sequence and stirred until fully dissolved to obtain a nitrate solution with a metal ion concentration of 150 g / L (Ni+Co+Mn), where nLi / n(Ni+Co+Mn) = 0.95.

[0059] 2. The nitrate solution obtained in step 1 is fed into a tank and dispersed into atomized droplets at a feed rate of 3 L / h through a two-fluid atomizer with an atomization pressure of 0.25 MPa. The carrier gas flow rate is 35 L / min. The atomized droplets are fed into a spray pyrolysis furnace for pyrolysis to obtain the desired oxide powder. The pyrolysis temperature is 680℃. The pyrolyzed powder product and vapor are separated and recovered using a bag filter.

[0060] Li prepared in Example 2 0.95 Ni 0.62 Co 0.07 Mn 0.31 O 1.48 The precursor material has a sphericity of 80.4% and a micronization rate of 14%.

[0061] The cathode material was prepared using the lithium-ion cathode material precursor prepared in Example 2. The preparation method was the same as in Example 1, except that the precursor was replaced with the precursor prepared in Example 2.

[0062] Example 3: This embodiment provides a method for preparing a lithium oxide precursor, which specifically includes the following steps: 2. According to the molar percentage of each metal element Ni:Co:Mn = 70:7:23 (mol%), nickel nitrate, cobalt nitrate, manganese nitrate and lithium nitrate are added to pure water in sequence and stirred until fully dissolved to obtain a nitrate solution with a metal ion concentration of 130 g / L (Ni+Co+Mn), where nLi / n(Ni+Co+Mn) = 1.00.

[0063] 2. The nitrate solution obtained in step 1 is fed into a tank and dispersed into atomized droplets at a feed rate of 3 L / h through a two-fluid atomizer with an atomization pressure of 0.25 MPa. The carrier gas flow rate is 40 L / min. The atomized droplets are fed into a spray pyrolysis furnace for pyrolysis to obtain the desired oxide powder. The pyrolysis temperature is 720℃. The pyrolyzed powder product and steam are separated and recovered using a bag filter.

[0064] LiNi prepared in Example 3 0.70 Co0.07 Mn 0.23 O 1.5 The precursor material has a sphericity of 81.7% and a micronization rate of 18%.

[0065] The cathode material was prepared using the lithium-ion cathode material precursor prepared in Example 3. The preparation method was the same as in Example 1, except that the precursor was replaced with the precursor prepared in Example 3.

[0066] Example 4: This embodiment provides a method for preparing a lithium oxide precursor, which specifically includes the following steps: 3. According to the molar percentage of each metal element Ni:Co:Mn = 60:10:30 (mol%), nickel nitrate, cobalt nitrate, manganese nitrate and lithium nitrate are added to pure water in sequence, and the remainder is made up with pure water. Stir to make it fully dissolved to obtain a nitrate solution with a metal ion concentration of 140 g / L (Ni+Co+Mn), where nLi / n(Ni+Co+Mn) = 1.01.

[0067] 2. The nitrate solution obtained in step 1 is fed into a tank and dispersed into atomized droplets at a feed rate of 4 L / h through a two-fluid atomizer with an atomization pressure of 0.25 MPa. The carrier gas flow rate is 40 L / min. The atomized droplets are fed into a spray pyrolysis furnace for pyrolysis to obtain the desired oxide powder. The pyrolysis temperature is 700℃. The pyrolysis powder product and steam are separated and recovered using a bag filter.

[0068] The Li prepared in Example 4 1.01 Ni 0.60 Co 0.10 Mn 0.30 O 1.51 The precursor material has a sphericity of 82.4% and a micronization rate of 17%.

[0069] The cathode material was prepared using the lithium-ion cathode material precursor prepared in Example 4. The preparation method was as follows: the precursor was placed in a sagger and spread evenly in a box furnace for sintering. The air flow rate was 20 L / min and the oxygen content was 20-21%. The temperature of the box furnace was set at 750°C in the first stage and maintained for 2 h; the temperature was set at 970°C in the second stage and maintained for 12 h. The heating rate in each stage was 5°C / min. After sintering, the cathode material was obtained by cooling to room temperature with the furnace, crushing, and sieving through a 400-mesh sieve.

[0070] Comparative Example 1 This comparative example first provides a method for preparing a lithium-ion battery cathode material precursor, specifically including the following steps: 1. According to the molar percentage of each metal element Ni:Co:Mn = 60:10:30 (mol%), nickel nitrate, cobalt nitrate, manganese nitrate and lithium nitrate are added to pure water in sequence and stirred until fully dissolved to obtain a nitrate solution with a metal ion concentration of 180 g / L (Ni+Co+Mn), where nLi / n(Ni+Co+Mn) = 1.00.

[0071] 2. The nitrate solution obtained in step one is fed into a tank and dispersed into droplets at a feed rate of 5 L / h using a two-fluid atomizer with an atomization pressure of 0.25 MPa. The carrier gas flow rate is 40 L / min. The atomized droplets are then fed into a spray pyrolysis furnace for pyrolysis to obtain the desired oxide powder. The pyrolysis temperature is 800 °C. The pyrolysis powder product and vapor are separated and recovered using a bag filter. The prepared LiNi 0.60 Co 0.10 Mn 0.30 O 1.5 Scanning electron microscopy of precursor materials, such as Figure 5 As shown, the precursor powder ratio of the lithium-ion cathode material obtained in this comparative example is 25%.

[0072] The cathode material was prepared using the lithium-ion cathode material precursor prepared in Comparative Example 1, and the preparation method was the same as in Example 1. The SEM images of the prepared cathode material are shown below. Figure 6 As shown.

[0073] Some performance parameters of the cathode material precursors obtained in the examples and comparative examples were tested. The test methods are as follows, and the test results are shown in Table 1.

[0074] The proportion of micronized particles: Select an appropriate SEM image, measure the major axis length of all complete secondary particles in the SEM image, and count the ratio of particles smaller than 1μm to the total number of particles. The major axis length refers to the maximum distance between any two points on the outer periphery of the secondary particle.

[0075] Surface density: Multiple (5) SEM images of the cathode material precursor were taken at a certain magnification (5000x) using a field emission scanning electron microscope (HITACHISU8100). The surface density of each SEM image was analyzed using the calculation formula: Surface density = 100% - Surface porosity. The average of the surface density of several (5) SEM images was then taken as the final surface density.

[0076] Surface porosity: Adjust the scanning electron microscope (SEM) to a suitable magnification and take an SEM image of the surface of the secondary particles of the cathode material precursor. Then, analyze the surface SEM image using image analysis software and calculate the porosity. For example, the magnification of the surface SEM image can be 7.0K, 9.0K, 10.0K, 13K, 20K, or 30K, etc. The specific magnification is preferably such that there is only one complete or nearly complete single secondary particle sphere in the SEM field of view.

[0077] Sphericity: Calculated using the projected area and perimeter of lithium oxide precursor particles in a 1000x electron microscope using the Metis software, and according to... Calculated.

[0078] Tap density: Test method: The tap density was determined by a powder tap density tester (model: Dandong Baite BT-302) in accordance with the national standard GB / T 5162-2021 Determination of tap density of metal powder.

[0079] D50: Volume average particle size Dv50 and Span are determined by referring to GB / T19077-2016 and conveniently using a laser particle size analyzer. The Mastersizer 3000 laser particle size analyzer from Marvin Instruments Co., Ltd. can be used as the testing instrument.

[0080] Table 1 Summary of parameters of the precursors prepared in Examples 1-4 and Comparative Example 1

[0081] The positive electrode material obtained from the examples and comparative examples, conductive carbon black (Super P), and binder PVDF were mixed at a mass ratio of 8:1:1. An appropriate amount of NMP was added as a solvent, and the mixture was magnetically stirred for 4 hours to form a uniform slurry. The slurry was uniformly coated onto aluminum foil, vacuum dried at 80°C for 12 hours, and then rolled and punched into positive electrode discs with a diameter of 12 mm.

[0082] Using lithium metal sheets as the negative electrode and Celgard 2400 as the separator, the electrolyte was 1M LiPF6 dissolved in EC / DMC (volume ratio 1:1). In a high-purity argon glove box (O2 < 0.1 ppm, H2O < 0.1 ppm), the negative electrode shell, positive electrode sheet, separator, lithium sheet, gasket, spring, and positive electrode shell were assembled sequentially and sealed to obtain a button cell. Electrochemical performance was tested at 25°C using a Blue Electric testing system, with a voltage range of 3.0–4.45 V. Cycling performance was tested at a 1C rate (1C = 190 mA / g) within the same voltage range.

[0083] The test results are shown in Table 2.

[0084] Table 2 Comparison of electrochemical data of cathode materials prepared from precursors in Examples 1-4 and Comparative Example 1

[0085] Brief analysis of experimental data: The precursor prepared in this embodiment has a low micronization rate, resulting in a single-crystal cathode material with rounded shape and an extremely low micronization rate. This leads to excellent overall performance in terms of initial efficiency, capacity, rate capability, and cycle life. The reasons for these superior performances are analyzed as follows: First, the one-step spray pyrolysis method achieves molecular-level mixing of the lithium source and transition metal salt in the solution stage. After pyrolysis, lithium elements are uniformly distributed at the atomic level within the particles. During sintering, lithium ions are orderly embedded along the lattice channels, forming a highly complete layered structure. Second, the low micronization rate of the precursor helps reduce micronization in the single-crystal cathode material, thereby significantly improving the cycle stability of the product. In addition, the lithium oxide precursor in this application avoids the mechanical damage and impurity contamination introduced by the traditional lithium mixing-ball milling process. The residual lithium content (Li2CO3, LiOH) on the material surface is significantly reduced, further reducing gas expansion and impedance growth problems. In summary, the atomically uniform distribution of the lithium source, the rounded and smooth particle morphology, and the high surface activity jointly ensure that the cathode material of this embodiment possesses both high capacity and long cycle life.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lithium oxide precursor, characterized in that, The micronization rate of the lithium oxide precursor is ≤20%, where the micronization rate refers to the percentage of secondary particles with a particle size of 1 μm or less.

2. The lithium oxide precursor according to claim 1, characterized in that, The lithium oxide precursor satisfies one or more of the following conditions; ① The specific surface area of ​​the lithium oxide precursor is 10-30 m². 2 / g; preferably, the specific surface area is 15-25 m². 2 / g; ② The surface density of the lithium oxide precursor is 10-25%; ③ The sphericity of the secondary particles in the lithium oxide precursor is ≥80%; ④ The tap density of the lithium oxide precursor is 1.0-1.5 g / cm³. 3 ; ⑤ The D50 of the lithium oxide precursor is 3-15 μm; ⑥ The lithium oxide precursor includes secondary particles formed by the aggregation of primary particles, wherein the primary particles are nanoparticles.

3. The lithium oxide precursor according to claim 1, characterized in that, The chemical formula of the lithium oxide precursor is Li x Ni a Co b Mn c Me d O 1+0.5x Where 0.6≤x≤1.05, 0<a<1, 0≤b<1, 0≤c<1, a+b+c+d=1, and Me is selected from at least one of Na, K, Ca, Sr, Y, Ti, Zr, Nb, Sb, Fe, Cu, Zn, B, and W.

4. The lithium oxide precursor according to claim 1, characterized in that, The lithium oxide precursor exhibits diffraction peaks at 18.0°~22.0°, 36.0°~40.0°, 42.0°~46.0°, and 62.0°~66.0° in powder X-ray diffraction patterns using Cu-Kα rays.

5. A method for preparing a lithium oxide precursor according to any one of claims 1-4, characterized in that, The lithium oxide precursor is obtained by spray pyrolysis of a mixed salt solution containing metal ions, wherein the metal ions include nickel and lithium; preferably, all metal elements also include at least one of manganese and cobalt.

6. The method for preparing the lithium oxide precursor according to claim 5, characterized in that, The preparation method satisfies one or more of the following conditions; A. The nickel and lithium elements exist in the mixed salt solution in the form of nitrates; B. The manganese or cobalt element exists in the mixed salt solution in the form of nitrate; C. The total concentration of metal elements in the mixed salt solution is 110~190g / L; D. The mixed salt solution further includes at least one of Na, K, Ca, Sr, Y, Ti, Zr, Nb, Sb, Fe, Cu, Zn, B, and W; E. The ratio of the amount of lithium in the mixed salt solution to the sum of the amounts of other metal elements is ≤1.

7. The method for preparing the lithium oxide precursor according to claim 5, characterized in that, The spray pyrolysis temperature is 600-780℃; And / or, the spray pyrolysis pressure is 0.2-0.4 MPa, the feed rate is 2-10 L / h, and the carrier gas flow rate is 30-50 L / min; And / or, the spray pyrolysis is performed using a two-fluid spray gun.

8. A positive electrode material, characterized in that, The material is obtained by sintering a lithium oxide precursor, including any one of the lithium oxide precursors described in claims 1-4 or the lithium oxide precursor prepared by any one of the preparation methods described in claims 5-7.

9. The cathode material according to claim 8, characterized in that, The sintering process includes a first-stage sintering and a second-stage sintering. The first-stage sintering temperature is 700-800℃, and the time is 1.5-2.5 hours. The second-stage sintering temperature is 950-1000℃, and the time is 10-14 hours. And / or, the sintering includes a first-stage sintering and a second-stage sintering, wherein the heating rate of the first-stage sintering and the second-stage sintering is 4-6℃ / min; And / or, the sintering atmosphere includes oxygen and an inert gas, wherein the volume fraction of oxygen is 20-21%; And / or, the material may also include lithium carbonate.

10. A secondary battery, characterized in that, Includes the cathode material as described in claim 9.

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