Ultra-high nickel positive electrode material precursor, preparation method thereof, positive electrode material and battery

Abstract

This invention discloses an ultra-high nickel cathode material precursor, its preparation method, cathode material, and battery, belonging to the field of battery technology. The preparation of the ultra-high nickel cathode material precursor includes the following steps: adding a mixed metal sulfate solution, a sodium gallate solution, a complexing agent, and a precipitant to a base solution for co-precipitation reaction until the particle size of the resulting particles reaches a preset value; the complexing agent is an oxalic acid solution; and the precipitant is a sodium hydroxide solution. This application achieves gallium doping during the precursor preparation reaction stage by co-precipitating gallium with other raw materials in the reaction system using a sodium gallate solution, thus avoiding Ga doping. 3+ The first precipitation allows for molecular-level mixing of metal elements, resulting in a hydroxide precursor with a more uniform elemental distribution. This is beneficial for improving the stability of the layered structure of the high-nickel precursor material, expanding the interlayer spacing, and thus enhancing the material's cycle stability.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to an ultra-high nickel cathode material precursor, its preparation method, cathode material, and battery. Background Technology

[0002] In recent years, lithium-ion batteries have become a research hotspot in the field of chemical power sources due to their advantages such as high voltage, high power, stable discharge voltage, wide applicability, broad operating range, and long service life. Since the capacity of a lithium-ion battery is ultimately determined by the cathode material, research on cathode materials is crucial for improving the overall performance of lithium-ion batteries. Layered NCM ternary cathode materials have been widely used in many fields such as digital devices, laptops, and electric vehicles in recent years due to their advantages such as high specific capacity, low cost, long cycle life, and no memory effect. Among the many ternary cathode materials, high-nickel ternary cathode materials (LiNi...) are particularly noteworthy. 1-x-y Co x Mn y O2 (1-xy > 0.6) has advantages such as high specific capacity, high compaction density, good rate performance, and low cost, which can meet the requirements of low cobalt and high energy density of next-generation power batteries, and is one of the promising ternary cathode materials.

[0003] The main raw material for producing ternary cathode materials is the ternary precursor. The sphericity, crystallinity, elemental ratio, specific surface area, and particle size of the ternary precursor will affect the performance of the ternary cathode material. In addition to being related to ammonia concentration, stirring intensity, reaction temperature, pH value, reaction time, solid content, and impurity content, the various physical and chemical properties of the precursor are also related to the synthesis process.

[0004] In NCM ternary precursors, nickel is primarily an electrochemically active element. Increasing nickel content helps improve the material's capacity, thereby increasing energy density. Cobalt reduces electrochemical polarization and improves rate performance; however, excessive cobalt can reduce reversible capacity. Manganese ensures structural and thermal stability, reducing costs and improving safety; however, excessive manganese can disrupt the material's original layered structure. In short, higher nickel content results in greater battery energy density, significantly increasing battery life after a single charge and extending the driving range of vehicle power batteries. High-nickel power batteries have solved the problem of battery lightweighting, offering far superior space-saving capabilities compared to ordinary ternary batteries. Furthermore, the increased nickel content reduces cobalt usage, thus lowering production costs to some extent.

[0005] However, high-nickel ternary precursors are prone to phase transitions under high voltage cycling, resulting in poor cycling performance, and these problems have also greatly reduced their large-scale commercial production to some extent.

[0006] The cycle performance of lithium-ion battery cathode materials is mainly related to the material's structure and surface properties. Researchers have found that these materials can be modified through elemental doping or surface modification. For example, ion doping, surface coating, and electrolyte additives can improve the poor cycle performance of high-nickel ternary cathode materials. Some elemental doping can replace Ni in the cathode material. 2+ The position of the element, thereby reducing Li + / Ni 2+ The mixing phenomenon can also increase the interlayer spacing of the crystal structure, thereby reducing the Li + It reduces migration resistance; at the same time, it can also enhance crystal structure stability or increase specific capacity, thereby improving the cycle stability of ternary lithium-ion batteries.

[0007] In existing technologies, common doping elements include magnesium (Mg), aluminum (Al), titanium (Ti), zirconium (Zr), and fluorine (F), with some also using gallium (Ga). Doping of metallic elements is mostly achieved during the sintering stage, but this process often results in uneven doping, making it difficult to guarantee the final effect.

[0008] In view of this, the present invention is proposed. Summary of the Invention

[0009] One of the objectives of this invention is to provide a method for preparing an ultra-high nickel cathode material precursor. This method can obtain an ultra-high nickel cathode material precursor with relatively uniform elemental distribution, which is beneficial to improving the stability of the layered structure of the high nickel precursor material, expanding the interlayer spacing of the material, and thus improving the cycle stability of the material.

[0010] The second objective of this invention is to provide an ultra-high nickel cathode material precursor prepared by the above-described preparation method.

[0011] The third objective of this invention is to provide a cathode material further obtained from the above-mentioned precursor.

[0012] The fourth objective of this invention is to provide a battery having the above-mentioned positive electrode material.

[0013] This application can be implemented as follows:

[0014] In a first aspect, this application provides a method for preparing an ultra-high nickel cathode material precursor, which includes the following steps: adding a mixed metal sulfate solution, a sodium gallate solution, a complexing agent, and a precipitant to a base solution for co-precipitation reaction until the particle size of the particles obtained from the reaction reaches a preset value.

[0015] The complexing agent is oxalic acid solution; the precipitant is sodium hydroxide solution.

[0016] In an optional embodiment, the mixed metal sulfate solution has at least one of the following characteristics:

[0017] Feature 1: Mixed metal sulfate solutions include nickel-containing sulfate solutions, cobalt-containing sulfate solutions, and manganese-containing sulfate solutions;

[0018] Feature 2: The total concentration of mixed metals in the mixed metal sulfate solution is 1.5-3 mol / L.

[0019] In an optional embodiment, the preparation of the sodium metagabate solution includes mixing water, sodium hydroxide, and gallium sulfate.

[0020] In an optional embodiment, the concentration of the oxalic acid solution is 0.25-1.5 mol / L; and / or, the concentration of sodium hydroxide in the precipitant is 20-40 wt%.

[0021] In an optional embodiment, the base liquid includes at least one of the following characteristics:

[0022] Feature 1: The base liquid includes water, a complexing agent, and a precipitant;

[0023] Feature 2: The volume of water in the bottom liquid is 40-60% of the volume of the reaction vessel;

[0024] Feature 3: The complexing agent in the base solution is oxalic acid solution, with a concentration of 0.25-1.5 mol / L;

[0025] Feature 4: The precipitant in the bottom liquid is a sodium hydroxide solution;

[0026] Feature 5: The pH value of the base solution is 11.6-12.0.

[0027] In an optional embodiment, the coprecipitation reaction has at least one of the following characteristics:

[0028] Feature 1: The reaction takes place under a protective gas atmosphere;

[0029] Feature 2: The coprecipitation reaction is carried out by adding a mixed metal sulfate solution, a sodium gallate solution, a complexing agent, and a precipitant to the bottom solution in a co-current flow under stirring conditions;

[0030] Feature 3: The reaction temperature is 50-65℃;

[0031] Feature 4: For the first 4 hours of the reaction, the flow rate of the mixed metal sulfate solution is 2 L / h. The mixed metal sulfate solution includes nickel-containing sulfate solution, cobalt-containing sulfate solution, and manganese-containing sulfate solution; the total concentration of the mixed metals in the mixed metal sulfate solution is 1.5-3 mol / L; the precipitant is an oxalic acid solution with a concentration of 0.25-1.5 mol / L, and the oxalate concentration is 0.5 mol / L when the precipitant is added to the reaction vessel. The precipitant is a sodium hydroxide solution, and the addition of the precipitant is to control the pH of the reaction system in the reaction vessel to be 11.6-12.0; the concentration of the sodium gallate solution is 0.1-0.5 mol / L, and the flow rate of the sodium gallate solution is 0.3 L / h.

[0032] After 4 hours of reaction, the pH of the reaction system was decreased at a rate of 0.05 ppm per hour until the pH of the reaction system dropped to 11.0-11.4.

[0033] In an optional embodiment, post-treatment is also included after the co-precipitation reaction;

[0034] Post-processing includes: solid-liquid separation, centrifugal washing, demagnetization, drying, sieving, and mixing of the slurry obtained from the co-precipitation reaction;

[0035] Post-processing includes at least one of the following features:

[0036] Feature 1: Centrifugal washing includes: washing with 1-3 mol / L sodium hydroxide alkali for 10-30 min to remove excess sulfate ions; then washing with hot water at 70-100℃ for 20-60 min to remove excess sodium ions;

[0037] Feature 2: When the Na content in the solid sample after centrifugation and washing is ≤100ppm and the S content is ≤1000ppm, the sample is demagnetized.

[0038] Feature 3: When the magnetic foreign matter in the demagnetized sample is ≤100μg / kg, the sample is dried at 80-120℃;

[0039] Feature 4: When the sample moisture content is dried to ≤0.8%, the sample is sieved.

[0040] Secondly, this application provides an ultra-high nickel cathode material precursor, which is prepared by any of the preparation methods described in the foregoing embodiments.

[0041] Ultra-high nickel cathode material precursors have at least one of the following characteristics:

[0042] Feature 1: The general chemical formula of the ultra-high nickel cathode material precursor is Ni 1-x-y-z Co x Mn y Gaz (OH)2, where 1-xyz > 0.9;

[0043] Feature 2: The primary particles of the ultra-high nickel cathode material precursor are in the form of thin sheets;

[0044] Feature 3: The primary particles of the ultra-high nickel cathode material precursor have a length of 50-70 nm;

[0045] Feature 4: The width of the primary particles in the ultra-high nickel cathode material precursor is 10-20 nm;

[0046] Feature 5: The secondary particles of the ultra-high nickel cathode material precursor are spherical or near-spherical, with a particle size of 2.5-3.5 μm;

[0047] Feature 6: The average particle size of the ultra-high nickel cathode material precursor is 2-3 μm.

[0048] Thirdly, this application provides a cathode material, the precursor of which is the ultra-high nickel cathode material precursor of the aforementioned embodiments.

[0049] Fourthly, this application provides a battery having the positive electrode material of the aforementioned embodiments.

[0050] The beneficial effects of this application include:

[0051] This application achieves gallium doping during the precursor preparation reaction stage by co-precipitating gallium with other raw materials in the reaction system using a sodium gallate solution, thus avoiding Ga doping. 3+ The first precipitation allows for molecular-level mixing of metal elements, resulting in a hydroxide precursor with a more uniform elemental distribution. This is beneficial for improving the stability of the layered structure of the high-nickel precursor material, expanding the interlayer spacing, and thus enhancing the material's cycle stability.

[0052] Trivalent gallium itself is not electrochemically active, but it forms Ga-O bonds, creating a pillar effect in the crystal. Furthermore, stronger Ga-O bond energies not only enhance the stability of the layered structure but also increase the interlayer spacing, promoting Li... + This facilitates the transport of Ga elements, thereby improving the cycling stability of the material. Furthermore, Ga doping has no effect on the morphology or particle size of the ternary precursor, nor does it alter its inherent structure.

[0053] The obtained precursor can be further processed into cathode material, and then into battery. The corresponding battery can have better specific capacity and capacity retention. Attached Figure Description

[0054] 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.

[0055] Figure 1 This is a SEM image of the precursor obtained in Example 1 of this application;

[0056] Figure 2 Here is a SEM image of the precursor obtained in Comparative Example 1 of this application;

[0057] Figure 3 Here is a SEM image of the precursor obtained in Comparative Example 2 of this application;

[0058] Figure 4 This is a SEM image of the precursor obtained in Comparative Example 3 of this application. Detailed Implementation

[0059] 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.

[0060] The following provides a detailed description of the ultra-high nickel cathode material precursor, its preparation method, cathode material, and battery provided in this application.

[0061] Compared to aluminum (ionic radius: 0.057 nm), a commonly used doping element, trivalent gallium has a larger ionic radius (ionic radius: 0.062 nm). Although trivalent gallium itself is not electrochemically active, it forms Ga-O bonds, creating a pillar effect in the crystal. Furthermore, the stronger Ga-O bond energy not only enhances the layered structure stability of the material but also widens the interlayer spacing, promoting Li... + This facilitates the transport of Ga elements, thereby improving the cycling stability of the material. Furthermore, Ga doping has no effect on the morphology or particle size of the ternary precursor, nor does it alter its inherent structure.

[0062] Currently, some existing technologies offer gallium doping schemes that are difficult to form hydroxide precursors with a relatively uniform distribution of metal elements.

[0063] The inventors proposed through research that, based on the stability constants of different metal ions and ammonia complexes in Table 1, Ga... 3+ The stability constant of the -ammonia complex is missing, from which it can be inferred that Ga3+ Complexes with ammonia are unstable in aqueous solution and readily decompose; or Ga 3+ It will directly combine with hydroxide ions in ammonia solution to form hydroxide precipitates. That is, using ammonia as a complexing agent and gallium sulfate solution alone cannot achieve the purpose of co-precipitation between the various metal ions, thus failing to obtain a hydroxide precursor with a relatively uniform distribution of the various metal elements.

[0064] Furthermore, based on the stability constants of different metal ions and oxalic acid complexes in Table 2, oxalic acid can form stable complexes with the metals listed in the table. Theoretically, this could improve the uniformity of transition metal distribution, thereby enhancing electrochemical performance. However, since the stability constants of Ga-oxalic acid complexes differ significantly from those of Ni-oxalic acid, Co-oxalic acid, or Mn-oxalic acid complexes, further treatment of the gallium sulfate solution is required to achieve co-precipitation with Ni, Co, and Mn metals.

[0065] From Table 3, the solubility constants K of different metal hydroxides are... sp In terms of K values, Ga(OH)3 has a smaller K value compared to Ni(OH)2, Co(OH)2, and Mn(OH)2. SP Trivalent gallium will first combine with hydroxide ions to form gallium hydroxide. As an amphoteric hydroxide, gallium hydroxide has the same properties as aluminum hydroxide.

[0066] Table 1. Stability constants of complexes of different metal ions with ammonia.

[0067]

[0068] Table 2 Stability constants of complexes of different metal ions with oxalic acid

[0069]

[0070]

[0071] Table 3 Solubility product constants Ksp of different metal oxides

[0072] metal oxides <![CDATA[Solubility product constant K sp > <![CDATA[Precipitation equilibrium constant (K M = 1 / K sp )]]> <![CDATA[Mn(OH)2]]> <![CDATA[1.9×10 -13 ]]> <![CDATA[5.26×10 14 ]]> <![CDATA[Ni(OH)2]]> <![CDATA[5.48×10 -16 ]]> <![CDATA[1.83×10 17 ]]> <![CDATA[Co(OH)2]]> <![CDATA[1.9×10 -15 ]]> <![CDATA[5.26×10 16 ]]> <![CDATA[Al(OH)3]]> <![CDATA[1.3×10 -33 ]]> <![CDATA[7.69×10 34 ]]> <![CDATA[Ga(OH)3]]> <![CDATA[7.28×10 -36 ]]> <![CDATA[1.37×10 37 ]]>

[0073] Based on this, this application creatively proposes to perform doping during the precursor preparation reaction stage, using sodium gallate solution and other substances in the reaction system (such as metal sulfate solution, complexing agent, and precipitant) to participate in the co-precipitation reaction. This method can, to some extent, avoid Ga… 3+ The first precipitation allows for molecular-level mixing of metal elements, ultimately synthesizing a hydroxide precursor with a relatively uniform distribution of metal elements.

[0074] For reference, this application provides a method for preparing an ultra-high nickel cathode material precursor, which includes the following steps: adding a mixed metal sulfate solution, a sodium gallate solution, a complexing agent, and a precipitant to a base solution for co-precipitation reaction until the particle size of the resulting particles reaches a preset value.

[0075] In this application, the base liquid includes water, a complexing agent, and a precipitant. That is, part of the complexing agent and precipitant are first prepared into the base liquid, and the remaining part of the complexing agent and precipitant are subsequently added to the base liquid in a co-current manner.

[0076] In some embodiments, the volume of water in the base solution can be 40-60% of the reaction vessel volume, such as 40%, 45%, 50%, 55%, or 60%, or any other value within the range of 40-60%. The complexing agent and precipitant in the base solution are the same as those subsequently required and flowing into the base solution.

[0077] For reference, the pH of the substrate solution can be 11.6-12.0, such as 11.6, 11.7, 11.8, 11.9, or 12.0, or any other value within the range of 11.6-12.0. The pH of the substrate solution can be adjusted using a precipitant.

[0078] The aforementioned mixed metal sulfate solution includes a nickel-containing sulfate solution, a cobalt-containing sulfate solution, and a manganese-containing sulfate solution. For example, the nickel-containing sulfate solution may be a NiSO4·6H2O solution, the cobalt-containing sulfate solution may be a CoSO4·7H2O solution, and the manganese-containing sulfate solution may be a MnSO4·H2O solution.

[0079] The total concentration of the mixed metals in a mixed metal sulfate solution can be 1.5-3 mol / L, such as 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L, or any other value within the range of 1.5-3 mol / L.

[0080] In some embodiments, the preparation of the sodium gallate solution includes mixing water, sodium hydroxide, and gallium sulfate. The gallium sulfate solution can be understood as a gallium sulfate solution (Ga₂(SO₄)₃ solution). A sodium gallate solution of a certain concentration can be prepared by simply dissolving soluble gallium sulfate in excess sodium hydroxide and water.

[0081] The concentration of sodium gallate solution is 0.1-0.5 mol / L, such as 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, or 0.5 mol / L, or any other value within the range of 0.1-0.5 mol / L.

[0082] In this application, the complexing agent is an oxalic acid solution. Exemplarily, the concentration of the oxalic acid solution can be 0.25-1.5 mol / L, such as 0.25 mol / L, 0.5 mol / L, 0.75 mol / L, 1 mol / L, 1.25 mol / L, or 1.5 mol / L, or any other value within the range of 0.25-1.5 mol / L.

[0083] The precipitant is a sodium hydroxide solution. The precipitant is mainly used to control the pH value of the reaction system or the base solution, and its dosage and concentration can be adjusted accordingly based on the pH value. The concentration of sodium hydroxide in the precipitant can be 20-40 wt%, such as 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%, or any other value within the range of 20-40 wt%.

[0084] In this application, the coprecipitation reaction can be carried out under a protective gas atmosphere (such as nitrogen, argon, or helium).

[0085] Preferably, the mixed metal sulfate solution, sodium gallate solution, complexing agent, and precipitant are added to the base liquid in a co-current manner under stirring conditions. The stirring speed can be 700-900 rpm, such as 700 rpm, 750 rpm, 800 rpm, 850 rpm, or 900 rpm, or any other value within the range of 700-900 rpm.

[0086] The temperature for the coprecipitation reaction can be 50-65℃, such as 50℃, 52℃, 55℃, 58℃, 60℃, 62℃ or 65℃, or any other value within the range of 50-65℃.

[0087] If the reaction temperature is below 50℃, the crystallinity of the material will be poor; if the reaction temperature is above 65℃, it will easily lead to Mn... 2+ Oxidation.

[0088] In some embodiments, a mixed metal sulfate solution, a sodium gallate solution, a complexing agent, and a precipitant may be added to the substrate in the following manner:

[0089] For the first 0-4 hours of the reaction, the flow rate of the mixed metal sulfate solution can be 0-2 L / h (the mixed metal sulfate solution includes nickel-containing sulfate solution, cobalt-containing sulfate solution, and manganese-containing sulfate solution; the total concentration of the mixed metals in the mixed metal sulfate solution is 1.5-3 mol / L); the flow rate of the sodium gallate solution can be 0-0.3 L / h (the concentration of the sodium gallate solution is 0.1-0.5 mol / L); an oxalic acid solution with a concentration of 0.25-1.5 mol / L is added to bring the oxalate concentration in the reaction vessel to 0.5 mol / L; and sodium hydroxide is added to control the pH of the reaction system to 11.6-12.0.

[0090] After 0-4 hours of reaction, the pH of the reaction system is decreased at a rate of 0.05-0.1% per hour until the pH of the reaction system drops to 11.0-11.4. This pH condition is maintained until the precursor particle size reaches the preset value (during this process, the flow rate and concentration of the mixed metal sulfate solution, sodium gallate solution, and complexing agent remain unchanged; the flow rate and / or concentration of the precipitant can be adjusted).

[0091] In a further embodiment, after 15 hours of reaction, the flow rate of the mixed metal sulfate solution can be adjusted to 2-4 L / h, and the flow rate of the sodium gallate solution to 0.3-0.5 L / h (other conditions remain unchanged from the previous stage); after 35 hours of reaction, the flow rate of the mixed metal sulfate solution can be adjusted to 4-6 L / h, and the flow rate of the sodium gallate solution to 0.5-1.0 L / h (other conditions remain unchanged from the previous stage). This method helps to increase production capacity.

[0092] Furthermore, post-treatment is performed after the coprecipitation reaction.

[0093] For reference, post-processing includes: solid-liquid separation, centrifugal washing, demagnetization, drying, sieving, and mixing of the slurry obtained from the co-precipitation reaction.

[0094] The centrifugal washing process includes: washing with 1-3 mol / L (e.g., 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 3 mol / L) sodium hydroxide solution for 10-30 min (e.g., 10 min, 15 min, 20 min, 25 min, or 30 min) to remove excess sulfate ions; and then washing with hot water at 70-100℃ (e.g., 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, or 100℃) for 20-60 min (e.g., 20 min, 30 min, 40 min, 50 min, or 60 min) to remove excess sodium ions.

[0095] When the Na content in the solid sample after centrifugation and washing is ≤100ppm and the S content is ≤1000ppm, the sample is demagnetized. When the magnetic foreign matter content in the demagnetized sample is ≤100μg / kg, the sample is dried at 80-120℃. When the sample moisture content is ≤0.8%, the sample is sieved using a vibrating screen (e.g., 325 mesh).

[0096] It should be noted that the processes and methods involved in the post-processing in this application can be referred to the relevant prior art, and will not be elaborated on here.

[0097] Accordingly, this application provides an ultra-high nickel cathode material precursor, which is prepared by the above-described preparation method.

[0098] Ultra-high nickel cathode material precursors have at least one of the following characteristics:

[0099] The chemical formula of the ultra-high nickel cathode material precursor is Ni. 1-x-y-z Co x Mn y Ga z (OH)2, where 1-xyz>0.9.

[0100] The primary particles of the ultra-high nickel cathode material precursor are in the form of thin sheets. For example, the length of the primary particles of the ultra-high nickel cathode material precursor can be 50-70 nm, such as 50 nm, 55 nm, 60 nm, 65 nm, or 70 nm, or any other value within the range of 50-70 nm. The width of the primary particles of the ultra-high nickel cathode material precursor can be 10-20 nm, such as 10 nm, 12 nm, 15 nm, 18 nm, or 20 nm, or any other value within the range of 10-20 nm.

[0101] The secondary particles of this ultra-high nickel cathode material precursor are spherical or near-spherical. The particle size of the secondary particles can be 2.5-3.5 μm, such as 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm or 3.5 μm, or any other value within the range of 2.5-3.5 μm.

[0102] The average particle size of the ultra-high nickel cathode material precursor can be 2-3 μm, such as 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm or 3 μm, or any other value within the range of 2-3 μm.

[0103] The aforementioned ultra-high nickel cathode material precursor exhibits good morphological consistency and sphericity, a large specific surface area, high tap density, uniform particle size distribution, and uniform elemental distribution.

[0104] In addition, this application also provides a cathode material, the precursor of which is the aforementioned ultra-high nickel cathode material precursor.

[0105] In some embodiments, the positive electrode material can be prepared by the following methods:

[0106] The above-mentioned ultra-high nickel cathode material precursor and lithium hydroxide are mixed evenly at a metal molar ratio of 1:1.02, sintered at 750°C for 10 hours in an oxygen atmosphere, and then taken out, ground and pulverized.

[0107] In other embodiments, the cathode material may be prepared using other methods and conditions, which are not limited here.

[0108] The gallium-doped ultra-high nickel cathode material precursor provided in this application produces cathode materials with better cycle stability after sintering than cathode materials obtained after sintering undoped gallium NCM precursors.

[0109] Furthermore, this application also provides a battery having the aforementioned positive electrode material. This battery exhibits good electrochemical performance.

[0110] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0111] Example 1

[0112] This embodiment provides a gallium-doped ternary hydroxide precursor, the preparation method of which is as follows:

[0113] Step (1): Calculate the corresponding sulfate mass according to the Ni:Co:Mn molar ratio of 95:4:1. Prepare an NCM salt solution with a total metal concentration of 2 mol / L using pure water, consisting of nickel, cobalt, and manganese sulfates (NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O). This solution is denoted as Solution A. The nickel, cobalt, and manganese salts used in the NCM salt solution are NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O.

[0114] A sodium gallate solution was prepared by using only pure water and sodium hydroxide to form gallium sulfate, denoted as solution B. Gallium sulfate is Ga₂(SO₄).

[0115] The mass concentration of the NCM ternary salt solution is 120 g / L, and the concentration of the gallium sulfate salt solution is 0.3 mol / L.

[0116] Step (2): Prepare an oxalic acid solution with a concentration of 0.5 mol / L as a complexing agent, denoted as solution C; prepare a sodium hydroxide solution (liquid alkali solution, mass concentration of 32%) with a concentration of 10.8 mol / L as a precipitating agent, denoted as solution D.

[0117] Step (3): Add 50% pure water to the reactor by volume, and purge with 0.4 m³ of water. 3 After adding nitrogen gas at a rate of 900 rpm as a protective gas, start the stirring and heating program: stir at 900 rpm and temperature at 55°C, then add oxalic acid solution until the oxalate concentration in the reactor is 0.5 mol / L; when the temperature rises to about 55°C, add sodium hydroxide solution to adjust the pH of the reaction system to 11.60-12.00.

[0118] In step (4), under the conditions of step (3), solutions A, B, C, and D are simultaneously pumped into the reactor in a parallel flow manner to carry out the precipitation reaction. Solution A and solution B are pumped into the reactor at flow rates of 2 L / h and 0.3 L / h, respectively. Simultaneously, the oxalic acid solution and liquid alkali solution from step (2) are pumped into the reactor to maintain a constant oxalate concentration and pH value in the reaction system. For the first 4 hours of the reaction, the reactor system undergoes nucleation under conditions of an oxalate concentration of 0.5 mol / L and a pH value of 11.60-12.00. After 4 hours, the pH value is decreased at a rate of 0.05 mol / h until the pH value in the reaction system drops to 11.00-11.40.

[0119] Step (5): After the reaction reaches 15 hours, adjust the flow rate of solution A to 4 L / h and the flow rate of solution B to 0.5 L / h; after the reaction reaches 35 hours, adjust the flow rate of solution A to 6 L / h and the flow rate of solution B to 1.0 L / h. The flow rates of solutions C and D are adjusted according to the actual situation to maintain a constant oxalate concentration and pH in the reaction system. Stop feeding when the slurry particle size reaches 3.0 ± 0.2 μm.

[0120] Step (6): Place the slurry obtained in step (5) into an aging kettle, then pump it to a centrifuge to dry it and form a filter cake. Then wash it with 1 mol / L sodium hydroxide for 10 min to remove excess sulfate ions, and then wash it with 70℃ hot water for 20 min to remove excess sodium ions. When Na≤100ppm and S≤1000ppm in the sample, the sample is demagnetized. When the magnetic foreign matter in the demagnetized sample is ≤100μg / kg, the sample is dried at 100℃. When the sample moisture content is ≤0.8%, it is sieved (through a 325 mesh vibrating sieve) for demagnetization, mixed, and gallium-doped NCM ternary cathode material precursor is obtained, denoted as product A.

[0121] The morphology of product A obtained in step (6) is characterized as follows: Figure 1As shown in the figure, it can be seen that the primary particles of the precursor prepared in this embodiment are in the form of thin sheets with consistent particle morphology and good sphericity.

[0122] Example 2

[0123] The difference between this embodiment and Embodiment 1 is that:

[0124] Step (1): The total metal concentration in solution A is 1.5 mol / L.

[0125] The NCM ternary salt solution has a mass concentration of 120 g / L, and the sodium gallate solution has a concentration of 0.1 mol / L.

[0126] Step (2): Prepare an oxalic acid solution with a concentration of 0.25 mol / L as a complexing agent, denoted as solution C; prepare a sodium hydroxide solution (liquid alkali solution, mass concentration of 20%) with a concentration of 10.8 mol / L as a precipitating agent, denoted as solution D.

[0127] Step (3): Add 40% pure water to the reactor, stir at 700 rpm and at 50°C, and then add oxalic acid solution until the oxalate concentration in the reactor is 0.5 mol / L.

[0128] Example 3

[0129] The difference between this embodiment and Embodiment 1 is that:

[0130] Step (1): The total metal concentration in solution A is 3 mol / L.

[0131] A sodium gallate solution was prepared by using only pure water and sodium hydroxide to form gallium sulfate, denoted as solution B. Gallium sulfate is Ga₂(SO₄).

[0132] The NCM ternary salt solution has a mass concentration of 120 g / L, and the sodium gallate solution has a concentration of 0.5 mol / L.

[0133] Step (2): Prepare an oxalic acid solution with a concentration of 1.5 mol / L as a complexing agent, denoted as solution C; prepare a sodium hydroxide solution (liquid alkali solution, mass concentration of 40%) with a concentration of 10.8 mol / L as a precipitating agent, denoted as solution D.

[0134] Step (3): Add 60% pure water to the reactor, stir at 800 rpm and at 65°C, and then add oxalic acid solution until the oxalate concentration in the reactor is 0.5 mol / L.

[0135] The morphology tests of the precursors prepared in Examples 2 and 3 showed that the primary particles of the precursors were thin-film-shaped, with consistent particle morphology and good sphericity.

[0136] Comparative Example 1

[0137] The difference between this comparative example and Example 1 is that gallium doping is not performed, that is, there is no B solution in the co-flowing solution in step (4), and the NCM ternary cathode material precursor is obtained, which is denoted as product B.

[0138] The morphology of the obtained product B is characterized as follows: Figure 2 As shown in the figure, it can be seen that the morphology of the undoped NCM precursor is consistent with that of the doped precursor, which further illustrates that gallium doping does not change the morphology and particle size of the precursor.

[0139] Comparative Example 2

[0140] The difference between this comparative example and Example 1 is that ammonia was used as a complexing agent. An NCM ternary cathode material precursor was obtained, denoted as product C.

[0141] The morphology of the obtained product C is characterized as follows: Figure 3 As shown in the figure, the precursor particles obtained in this comparative example have poor morphological consistency and a large number of small particles are produced. This may be due to the use of ammonia as a complexing agent, where hydroxide ions in ammonia directly react with trivalent gallium to form hydroxides that precipitate separately.

[0142] Comparative Example 3

[0143] The difference between this comparative example and Example 1 is that a gallium hydroxide salt solution was directly prepared. Specifically, gallium sulfate was prepared separately using pure water to form a gallium sulfate salt solution, denoted as solution B. The concentration of the gallium sulfate salt solution was 0.3 mol / L. A gallium-doped NCM ternary cathode material precursor was obtained, denoted as product D.

[0144] The obtained product D was characterized by its morphology, such as... Figure 4 As shown in the figure, a small amount of small particles of the precursor obtained in this comparative example also appeared, indicating that oxalic acid, as a complexing agent, can cause metal ions to precipitate simultaneously to a certain extent. However, if gallium sulfate salt solution is prepared directly, a small amount of trivalent gallium will precipitate prematurely to form small particles of gallium hydroxide, resulting in uneven particle size.

[0145] Test case

[0146] The precursors prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were mixed with lithium hydroxide at a molar ratio of 1:1.02. After sintering at 750°C for 10 hours in an oxygen atmosphere, the mixture was removed, ground, and pulverized to obtain four cathode materials, which were denoted as E1, E2, E3, and E4, respectively.

[0147] Four positive electrode materials, E1, E2, E3, and E4, were mixed in a ratio of positive electrode material: conductive carbon: polyvinylidene fluoride (PVDF) of 90:5:5 to form slurries, which were then used to fabricate positive electrode sheets (with a compacted density of 3.3 g / cm³). 2 Lithium metal sheets were selected as the negative electrode material and assembled into 2025 button cells.

[0148] Using 1 mol / L LiPF6 / EC:DEC:DMC = 1:1:1 (V%) as the electrolyte (where EC is ethylene carbonate, DEC is diethyl carbonate, and DMC is dimethyl carbonate), after activation at 0.2C for three cycles, it was cycled 100 times at 0.2C. The discharge capacity at the first cycle and the discharge capacity at the 100th cycle were measured, and the capacity retention rate after 100 cycles was calculated. The charging voltage was 4.3V.

[0149] The capacity retention rate (%) after 100 cycles = discharge capacity at the 100th cycle / discharge capacity at the 1st cycle × 100%. The specific capacity and cycle retention rate of the material are shown in Table 4.

[0150] Table 4 Performance Comparison

[0151] Serial Number Specific capacity, mAh / g Capacity retention after 100 cycles Example 1 187.8 92％ Comparative Example 1 163.3 80％ Comparative Example 2 165.4 83％ Comparative Example 3 170.9 87％

[0152] As shown in Table 4, the precursor obtained in Example 1 exhibits significantly better specific capacity and cycle performance than Comparative Examples 1-3. This indicates that by changing the complexing agent and using a sodium gallate solution for co-precipitation, a more uniform precursor of the transition metal can be prepared to a certain extent, thereby improving the electrochemical performance of the material.

[0153] In summary, the solution provided in this application has at least the following advantages:

[0154] (1) Doping gallium in the reaction stage of the precursor is beneficial to achieve molecular-level mixing between metal elements and obtain a ternary precursor with a relatively uniform element distribution.

[0155] (2) Utilizing the amphoteric properties of gallium hydroxide, a gallium sulfate solution is first reacted with excess sodium hydroxide to generate a sodium gallate solution, which then participates in the co-precipitation reaction in the reaction system. This method can, to a certain extent, effectively avoid the Ga... 3+ The first to precipitate is the hydroxide precursor, which eventually synthesizes a relatively uniform distribution of metal elements.

[0156] (3) Using oxalic acid as a complexing agent and sodium hydroxide as a precipitant, a hydroxide precursor with a more uniform elemental distribution is synthesized to improve the electrochemical performance of the material;

[0157] (4) Gallium doping does not change the morphology and particle size of the ternary precursor. The resulting ultra-high nickel ternary precursor has good morphological consistency and sphericity, high tap density and uniform particle size distribution.

[0158] (5) Trivalent gallium itself is not electrochemically active, but it forms Ga-O bonds in the crystal, creating a pillar effect. Furthermore, stronger Ga-O bond energies not only enhance the stability of the layered structure of the material but also increase the interlayer spacing, promoting the growth of Li. + The transport of these components helps improve the cyclic stability of the material.

[0159] The above are merely preferred embodiments of the present invention and are not intended to limit the present 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 method for preparing an ultra-high nickel cathode material precursor, characterized in that, Includes the following steps: A mixed metal sulfate solution, sodium gallate solution, complexing agent, and precipitant are added to the base solution to carry out a co-precipitation reaction until the particle size of the resulting particles reaches the preset value. The mixed metal sulfate solution includes a nickel-containing sulfate solution, a cobalt-containing sulfate solution, and a manganese-containing sulfate solution. The preparation of the sodium gallate solution includes: mixing water, sodium hydroxide, and gallium sulfate; the complexing agent is oxalic acid solution; and the precipitant is sodium hydroxide solution. The coprecipitation reaction involves adding a mixed metal sulfate solution, a sodium gallate solution, a complexing agent, and a precipitant in a co-current stream to a base solution under stirring conditions. The reaction temperature is 50-65℃. For the first 4 hours of the reaction, the flow rate of the mixed metal sulfate solution is >0 and ≤2L / h. The mixed metal sulfate solution includes nickel-containing, cobalt-containing, and manganese-containing sulfate solutions. The total concentration of the mixed metals in the mixed metal sulfate solution is 1.5-3 mol / L. The complexing agent is an oxalic acid solution with a concentration of 0.25-1.5 mol / L, and the complexing agent is added to the reaction mixture in the reaction vessel. The concentration of oxalate in the system is 0.5 mol / L, and the precipitant is a sodium hydroxide solution. The precipitant is added to control the pH of the reaction system in the reaction vessel to be 11.6-12.

0. The concentration of sodium gallate solution is 0.1-0.5 mol / L, and the flow rate of sodium gallate solution is >0 and ≤0.3 L / h. After the reaction is carried out for 4 hours, the pH of the reaction system is decreased at a rate of 0.05-0.1 L / h until the pH of the reaction system drops to 11.0-11.

4.

2. The preparation method according to claim 1, characterized in that, The concentration of sodium hydroxide in the precipitant is 20-40 wt%.

3. The preparation method according to claim 1, characterized in that, The base liquid includes at least one of the following characteristics: Feature 1: The base liquid comprises water, a complexing agent, and a precipitating agent; Feature 2: The volume of water in the bottom liquid is 40-60% of the volume of the reaction vessel; Feature 3: The complexing agent in the base liquid is an oxalic acid solution, and the concentration of the oxalic acid solution is 0.25-1.5 mol / L; Feature 4: The precipitant in the bottom liquid is a sodium hydroxide solution; Feature 5: The pH value of the base liquid is 11.6-12.

0.

4. The preparation method according to claim 1, characterized in that, The coprecipitation reaction was carried out under a protective gas atmosphere.

5. The preparation method according to claim 1, characterized in that, It also includes post-treatment after the coprecipitation reaction; Post-processing includes: solid-liquid separation, centrifugal washing, demagnetization, drying, sieving, and mixing of the slurry obtained from the co-precipitation reaction; Post-processing includes at least one of the following features: Feature 1: Centrifugal washing includes: washing with 1-3 mol / L sodium hydroxide alkali for 10-30 min to remove excess sulfate ions; then washing with hot water at 70-100℃ for 20-60 min to remove excess sodium ions; Feature 2: When the Na content in the solid sample after centrifugation and washing is ≤100ppm and the S content is ≤1000ppm, the sample is demagnetized. Feature 3: When the magnetic foreign matter in the demagnetized sample is ≤100μg / kg, the sample is dried at 80-120℃; Feature 4: When the sample moisture content is dried to ≤0.8%, the sample is sieved.

6. A precursor for an ultra-high nickel cathode material, characterized in that, The ultra-high nickel cathode material precursor is prepared by the preparation method according to any one of claims 1-5; The ultra-high nickel cathode material precursor has at least one of the following characteristics: Feature 1: The chemical formula of the ultra-high nickel cathode material precursor is Ni 1-x-y-z Co x Mn y Ga z (OH)2, where 1-xyz > 0.9; Feature 2: The primary particles of the ultra-high nickel cathode material precursor are in the form of thin sheets; Feature 3: The length of the primary particles of the ultra-high nickel cathode material precursor is 50-70 nm; Feature 4: The width of the primary particles of the ultra-high nickel cathode material precursor is 10-20 nm; Feature 5: The secondary particles of the ultra-high nickel cathode material precursor are spherical or near-spherical, and the particle size of the secondary particles is 2.5-3.5μm; Feature 6: The average particle size of the ultra-high nickel cathode material precursor is 2-3 μm.

7. A positive electrode material, characterized in that, The precursor of the cathode material is the ultra-high nickel cathode material precursor as described in claim 6.

8. A battery, characterized in that, The battery has the positive electrode material as described in claim 7.

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