A nickel-cobalt-manganese ternary hydroxide, a preparation method thereof, a lithium-rich manganese-based positive electrode material and a lithium ion battery

Abstract

This invention provides a nickel-cobalt-manganese ternary hydroxide and its preparation method, a lithium-rich manganese-based cathode material, and a lithium-ion battery, belonging to the field of lithium batteries. The preparation method of this invention is carried out under a protective gas atmosphere and includes the following steps: mixing a metal salt solution, a precipitant solution, and a complexing agent solution separately by passing them into a base liquid; then performing a precipitation reaction and post-treatment on the resulting system to obtain the nickel-cobalt-manganese ternary hydroxide; the metal salt in the metal salt solution is a nickel salt, a cobalt salt, and a manganese salt; the precipitation reaction includes sequential nucleation, growth, and aging; at 25°C, the pH value of the system during nucleation is 11.5~12.5, and the pH value of the system during growth is 11~12; the flow rate of the metal salt solution during nucleation is 40~60% of the flow rate of the metal salt solution during growth. Through the synergistic control of high pH, ​​low flow rate nucleation, and suitable pH, normal flow rate growth, a dense spherical precursor is prepared.

Description

Technical Field

[0001] This invention relates to the field of lithium batteries, specifically to a nickel-cobalt-manganese ternary hydroxide and its preparation method, a lithium-rich manganese-based cathode material, and a lithium-ion battery. Background Technology

[0002] Lithium-rich manganese-based cathode materials (xLi2MnO3·(1-x)LiTMO2, TM=Ni, Co, Mn, etc.) are considered key materials for the next generation of high-energy-density lithium-ion batteries due to their ultra-high specific capacity (>250 mAh / g). Their performance is highly dependent on the physical and chemical properties of the precursor materials.

[0003] Currently, the chemical composition of Ni is generally prepared by the industry through conventional co-precipitation methods. a Co b Mn c The precursor of (OH)₂ has a main content of Ni, Co, and Mn, with the following percentage molar ratios: 0.10≤a≤0.50, 0.00≤b≤0.40, and 0.50≤c≤0.80. Within the particle size range of 2.0~6.0 μm, existing products typically exhibit low tap density (≤1.45 g / cm³). 3 The corresponding cathode material compaction density is <2.9 g / cm³. 3 This results in low battery volumetric energy density and a high specific surface area (BET≥20 m²). 2 The problem is that the primary particles are thin (<220 nm, insufficient structural strength, which affects the stability of the battery) and have many side reactions, resulting in poor battery cycle life. Summary of the Invention

[0004] This invention provides a nickel-cobalt-manganese ternary hydroxide and its preparation method, a lithium-rich manganese-based cathode material, and a lithium-ion battery. The nickel-cobalt-manganese ternary hydroxide prepared by this invention has high tap density, small specific surface area, and high thickness of lamellar particles.

[0005] This invention provides a method for preparing a nickel-cobalt-manganese ternary hydroxide, wherein the preparation method is carried out under a protective gas and includes the following steps: The metal salt solution, precipitant solution, and complexing agent solution were respectively introduced into the bottom liquid for mixing. Then, the resulting system underwent precipitation reaction and post-treatment to obtain the nickel-cobalt-manganese ternary hydroxide. The metal salts in the metal salt solution are nickel salts, cobalt salts, and manganese salts; The precipitation reaction includes nucleation, growth, and aging occurring sequentially. At 25°C, the pH value of the system during nucleation is 11.5~12.5, and the pH value of the system during growth is 11~12; The flow rate of the metal salt solution during nucleation is 40-60% of the flow rate of the metal salt solution during growth.

[0006] Preferably, the concentration of the metal salt in the metal salt solution is 1.5~2.5 mol / L; The nickel salt includes one or both of nickel sulfate and nickel acetate; the cobalt salt includes one or both of cobalt sulfate and cobalt acetate; the manganese salt includes one or both of manganese sulfate and manganese acetate.

[0007] Preferably, the complexing agent solution includes one or more of ammonia water, ammonium sulfate solution, ammonium chloride solution and ethylenediamine solution; The concentration of the complexing agent solution is 0.2~20 g / L.

[0008] Preferably, the precipitant solution includes a NaOH solution; the concentration of the precipitant solution is 4~10.5 mol / L.

[0009] Preferably, the ammonia value of the base solution is 0.2~2.0 g / L, and the pH value is 11.5~12.5 / 25℃.

[0010] Preferably, during the nucleation process, the flow rate ratio of the metal salt solution, the precipitant solution, and the complexing agent solution is 2:1:0.3~0.5.

[0011] Preferably, the precipitation reaction is carried out at a temperature of 40~60℃; During the nucleation process, the ammonia value of the system is 0.2~1.2 g / L, the time is 20~70h, and the D50 of the nucleated particles is 1.3~2.0 μm. During the growth process, the flow rate ratio of the metal salt solution, precipitant solution, and complexing agent solution is 2:0.9~1.1:0.3~0.5, the hourly inflow of the metal salt solution is 5~10% of the effective volume of the reactor, and the ammonia value of the system is 0.2~2g / L. The growth period is 30-200 hours. The D50 of the particles obtained from the growth is 2.3~5.6 μm.

[0012] This invention also provides a nickel-cobalt-manganese ternary hydroxide prepared by the preparation method described above, with a chemical composition of Ni a Co b Mn c (OH)₂, 0.10≤a≤0.50, 0.00<b≤0.40, 0.50≤c≤0.80, D50 is 2.3~5.7μm, tap density ≥1.45g / cm³ 3 BET specific surface area ≤ 22.00 m² 2 / g; The nickel-cobalt-manganese ternary hydroxide is an aggregate of lamellar particles with an average thickness >220 nm.

[0013] The present invention also provides a lithium-rich manganese-based cathode material, the raw materials for which include the nickel-cobalt-manganese ternary hydroxide, lithium source, dopant and coating agent as described in the above technical solution.

[0014] The present invention also provides a lithium-ion battery, characterized in that the positive electrode of the lithium-ion battery comprises the lithium-rich manganese-based positive electrode material described in the above technical solution.

[0015] This invention successfully prepared a dense spherical precursor (i.e., nickel-cobalt-manganese ternary hydroxide) with "thick lath" primary particles (>270 nm) through the synergistic control of "high pH, ​​low flow rate nucleation" and "suitable pH, normal flow rate growth": During the nucleation period, a high pH (11.5~12.5) + low metal salt solution flow rate (40~60% of the flow rate of the metal salt solution during growth) was used to form a dense crystal nucleus, laying the foundation for the growth of thick lath primary particles (>210 nm). The low flow rate in the early nucleation process can avoid excessive agglomeration caused by high flow rate, while the synthesis environment during the growth period allows the lath particles to fill the gaps (i.e., the pores formed when primary particles grow crosswise, into which other primary particles fall and grow), thereby increasing the tap density (≥1.45 g / cm³). 3 Thick, plate-like particles and smaller pores are associated with low BET (≤19 m). 2 The key to / g).

[0016] The preparation method of this invention is carried out entirely in a protective gas atmosphere, preventing the formation of Mn. 2+ Isooxidation ensures product composition uniformity and extremely high batch stability. It is worth noting that if the inert atmosphere protection is insufficient during post-processing, pyramid-shaped impurity particles will appear on the surface of the nickel-cobalt-manganese ternary hydroxide. Analysis shows these particles to be Mn3O4 and manganese hydroxide, among others. These impurities disrupt the material's uniformity, leading to a significant decrease in the initial efficiency and cycle life of the final cathode material. However, the preparation method of this invention, conducted entirely in a protective gas atmosphere, effectively avoids the formation of such impurities, ensuring excellent batch consistency and electrochemical performance.

[0017] The tap density of the nickel-cobalt-manganese ternary hydroxide prepared by this invention is significantly increased to 1.50 g / cm³. 3 The specific surface area of ​​BET decreased to 18 m². 2The lithium-ion battery prepared from the nickel-cobalt-manganese ternary hydroxide of this invention, after activation at 0.1C rate and within a voltage range of 2.0-4.8V, exhibits an initial discharge specific capacity exceeding 295 mAh / g. After 50 cycles at 1C rate and within a voltage range of 2.0-4.6V, its capacity retention is significantly superior to conventional materials, reaching over 93%. The nickel-cobalt-manganese ternary hydroxide prepared by this invention demonstrates good structural stability after sintering, exhibiting high capacity and excellent cycle life at a high voltage of 4.8V, thus enhancing the product's market competitiveness.

[0018] This invention achieves the comprehensive technical goals of high performance, low cost, and long lifespan from precursor to battery, and solves the key bottlenecks of existing technologies. Attached Figure Description

[0019] Figure 1 Here is a SEM image of the precursor obtained in Example 1; Figure 2 Here is a SEM image of the precursor obtained in Comparative Example 1; Figure 3 Here is a SEM image of the precursor obtained in Comparative Example 2; Figure 4 The image shows the SEM image of the precursor obtained in Comparative Example 3. Detailed Implementation

[0020] This invention provides a method for preparing a nickel-cobalt-manganese ternary hydroxide, wherein the preparation method is carried out under a protective gas and includes the following steps: The metal salt solution, precipitant solution, and complexing agent solution were respectively introduced into the bottom liquid for mixing. Then, the resulting system underwent precipitation reaction and post-treatment to obtain the nickel-cobalt-manganese ternary hydroxide. The metal salts in the metal salt solution are nickel salts, cobalt salts, and manganese salts; The precipitation reaction includes nucleation, growth, and aging occurring sequentially. At 25°C, the pH value of the system during nucleation is 11.5~12.5, and the pH value of the system during growth is 11~12; The flow rate of the metal salt solution during nucleation is 40-60% of the flow rate of the metal salt solution during growth.

[0021] In this invention, during the nucleation process, the flow rate ratio of the metal salt solution, the precipitant solution, and the complexing agent solution is preferably 2:1:0.3~0.5, and in a specific embodiment of this invention, it can be 2:1:0.4.

[0022] In this invention, the concentration of the metal salt in the metal salt solution is preferably 1.5~2.5 mol / L, and in specific embodiments of this invention, it can be 1.6mol / L, 1.7mol / L, 1.8mol / L, 1.9mol / L, 2mol / L, 2.1mol / L, 2.2mol / L, 2.3mol / L, or 2.4mol / L; the metal salt in the metal salt solution is a nickel salt, a cobalt salt, and a manganese salt; the nickel salt preferably includes one or two of nickel sulfate and nickel acetate; the cobalt salt preferably includes one or two of cobalt sulfate and cobalt acetate; the manganese salt preferably includes one or two of manganese sulfate and manganese acetate.

[0023] In this invention, the concentration of the complexing agent solution is preferably 0.2~20 g / L, and in specific embodiments of this invention, it can be 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, 13 mol / L, 14 mol / L, 15 mol / L, 16 mol / L, 17 mol / L, 18 mol / L, or 19 mol / L; the complexing agent solution preferably includes one or more of ammonia water, ammonium sulfate solution, ammonium chloride solution, and ethylenediamine solution.

[0024] In this invention, the concentration of the precipitant solution is preferably 4~10.5 mol / L, and in specific embodiments of this invention it can be 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L; the precipitant solution includes NaOH solution.

[0025] In this invention, the base liquid is preferably obtained by mixing a complexing agent solution and a precipitant solution.

[0026] In this invention, the ammonia value of the base solution is preferably 0.2~2.0 g / L, and in specific embodiments of this invention, it can be 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.7 g / L, 1.8 g / L, or 1.9 g / L; the pH value is preferably 11.5~12.5 at 25°C. In this invention, the ammonia value is defined as the ammonia value of the solution converted from the amount of HCl standard solution consumed during acid-base titration = C. HCl V HCl / V 被滴定溶液 ×17).

[0027] In this invention, the temperature of the precipitation reaction is preferably 40~60℃, and in specific embodiments of this invention it can be 45, 50 or 55℃.

[0028] In this invention, the flow rate of the metal salt solution during nucleation is 40-60% of the flow rate of the metal salt solution during growth; in specific embodiments of this invention, it can be 45%, 50%, or 55%. The precipitation reaction includes nucleation, growth and aging in sequence; the precipitation reaction is carried out in a protective gas.

[0029] In this invention, the nucleation is preferably carried out under stirring conditions, and the stirring speed is preferably 650~950 rpm. In specific embodiments of this invention, it can be 700 rpm, 750 rpm, 800 rpm, 850 rpm or 900 rpm.

[0030] In this invention, the pH value of the system during nucleation is 11.5~12.5 / 25℃, and in a specific embodiment of this invention it can be 12.

[0031] In this invention, the ammonia value of the nucleation system is preferably 0.2~1.2 g / L, and the time is preferably 20~70h. In specific embodiments of this invention, the ammonia value can be 0.3g / L, 0.4g / L, 0.5g / L, 0.6g / L, 0.7g / L, 0.8g / L, 0.9g / L, 1g / L, or 1.1g / L, and the time can be 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h, or 65h. The D50 of the nucleated particles is preferably 1.3~2.0μm, and in specific embodiments of this invention, it can be 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, or 1.9μm.

[0032] In this invention, the growth is preferably carried out under stirring conditions, and the stirring speed is preferably 650~950 rpm. In specific embodiments of this invention, it can be 700 rpm, 750 rpm, 800 rpm, 850 rpm or 900 rpm.

[0033] In this invention, during the growth process, the flow rate of the metal salt solution is preferably 4-10% of the effective volume of the reactor, and the ammonia concentration of the system is preferably 0.2-2 g / L. In specific embodiments of this invention, it can be 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.7 g / L, 1.8 g / L, or 1.9 g / L. The pH value is preferably 11-12 at 25°C, and in specific embodiments of this invention, it can be 11.5.

[0034] In this invention, the time for increasing the flow rate of the metal salt solution during nucleation to the flow rate during growth is preferably 2-10 hours, and in specific embodiments of this invention, it can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or 9 hours. The process of increasing the flow rate affects particle growth; controlling the time of flow rate increase within the above range is beneficial for obtaining particles with high tap density, small specific surface area, and high thickness of lath-like particles.

[0035] In this invention, the growth time is preferably 30-200 hours, and in specific embodiments of this invention, it can be 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, 100 hours, 110 hours, 120 hours, 130 hours, 140 hours, 150 hours, 160 hours, 170 hours, 180 hours, or 190 hours.

[0036] In this invention, the D50 of the grown particles is 2.3~5.6μm, and in specific embodiments of this invention, it can be 2.5μm, 2.8μm, 3μm, 3.2μm, 3.5μm, 4μm, 4.5μm, 4.8μm, 5μm or 5.5μm.

[0037] In this invention, the nucleation and growth process further includes: the reaction system is also discharged through a concentrator; the volumes of the introduced solution and the discharged solution are kept consistent.

[0038] In this invention, the stirring speed during aging is 300~500 rpm, and in specific embodiments of this invention, it can be 350 rpm, 400 rpm, or 450 rpm; the aging time is 1~6 hours, and in specific embodiments of this invention, it can be 2 hours, 3 hours, 4 hours, or 5 hours.

[0039] In this invention, the post-processing includes separating the aged system and then sequentially washing the resulting solid with water, washing with alkali, drying, sieving, removing iron, and packaging.

[0040] In this invention, the separation method preferably includes centrifugation and filtration. In specific embodiments of this invention, a filter press, centrifuge, or integrated machine can be used for separation.

[0041] In this invention, the water temperature used for the water washing is preferably 50~80℃; the alkaline solution used for the alkaline washing preferably includes a sodium hydroxide solution with a concentration of 0.5~2.0 mol / L, and the temperature of the alkaline solution is preferably 50~80℃.

[0042] This invention also provides a nickel-cobalt-manganese ternary hydroxide prepared by the preparation method described above, characterized in that its chemical composition is Ni a Co b Mnc(OH)₂ (0.10≤a≤0.50, 0.00≤b≤0.40, 0.50≤c≤0.80), D50 is 2.3~5.7μm, tap density ≥1.45g / cm³ 3 BET specific surface area ≤ 22.00 m² 2 / g.

[0043] In this invention, the nickel-cobalt-manganese ternary hydroxide is an aggregate of lamellar particles, and the average thickness of the lamellar particles is >220 nm.

[0044] The present invention also provides a lithium-rich manganese-based cathode material, the raw materials for which include the nickel-cobalt-manganese ternary hydroxide, lithium source, dopant and coating agent as described in the above technical solution.

[0045] In this invention, the lithium source preferably includes one or more of lithium carbonate, lithium hydroxide, and lithium oxide; The chemical composition of the lithium-rich manganese-based cathode material is Li 1+a [(Ni x Co y Mn z ) 1-b-c-d M1 b M2 c M3 d ]O 2.5 - δ X δ ; a>0, 0.10≤x≤0.50, 0.00≤y≤0.40, 0.50≤z≤0.80, M1, M2 and M3 are cationic additive element placeholders and b+c+d<1, X is anionic additive, δ is the amount added; In this invention, M1 is preferably Mg, M2 is preferably Al, and M3 is preferably Ti; the total mass of M1, M2, and M3 preferably accounts for 0.3 to 2.5% of the mass of the lithium-rich manganese-based cathode material.

[0046] In this invention, the coating agent preferably includes Nb2O5, Ta2O5 and ZrO2; the mass of the coating agent accounts for 0.25~2.5% of the total mass of the raw materials.

[0047] In this invention, the D50 of the lithium-rich manganese-based cathode material is preferably 2.0~6.0 μm, and the tap density is preferably ≥1.70 g / cm³. 3 The preferred compaction density is ≥2.85 g / cm³. 3 The preferred specific surface area for BET is ≤1.5m². 2 / g.

[0048] In this invention, the preparation method of the lithium-rich manganese-based cathode material preferably includes the following steps: Nickel-cobalt-manganese ternary hydroxide, lithium source and dopant are mixed and sintered. The sintered product is then coated with a coating agent and heat-treated.

[0049] In this invention, the sintering is preferably carried out in oxygen; the sintering preferably includes a first sintering and a second sintering performed sequentially.

[0050] In this invention, the first sintering temperature is preferably 450~550℃ and the time is preferably 4~6h. In a specific embodiment of this invention, the first sintering temperature can be 500℃ and the time can be 5h. The heating rate to the first sintering temperature is preferably 2~5℃ / min. In a specific embodiment of this invention, it can be 3℃ / min or 4℃ / min.

[0051] In this invention, the second sintering temperature is preferably 820~950℃, and the time is preferably 12~18h. In a specific embodiment of this invention, the first sintering temperature can be 850℃ or 900℃, and the time can be 13h, 14h, 15h, 16h or 17h. The heating rate to the second sintering temperature is preferably 1~5℃ / min, and in a specific embodiment of this invention, it can be 2℃ / min, 3℃ / min or 4℃ / min.

[0052] In this invention, the heat treatment temperature is preferably 600°C and the time is preferably 6 hours.

[0053] The present invention also provides a lithium-ion battery, wherein the positive electrode of the lithium-ion battery comprises the lithium-rich manganese-based positive electrode material described in the above technical solution.

[0054] The following detailed description, in conjunction with embodiments, illustrates the nickel-cobalt-manganese ternary hydroxide and its preparation method, the lithium-rich manganese-based cathode material, and the lithium-ion battery provided by this invention. However, these descriptions should not be construed as limiting the scope of protection of this invention.

[0055] Example 1 Precursor P1 Ni 16.67 Co 16.67 Mn 66.66 Preparation of (OH)2 Add 80 L of pure water to the reactor, purge with nitrogen for protection, and start stirring at 900 rpm. Add 100 g / L ammonia solution to adjust the ammonia value of the bottom solution to 0.60 g / L, and add 420 g / L sodium hydroxide solution to adjust the pH to 12.10 / 25℃. Control the temperature at 50℃.

[0056] Nucleation stage: A mixed salt solution of 2.0 mol / L (with a molar ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 1:1:4), a 4 mol / L sodium hydroxide solution, and a 6.0 g / L ammonia solution are simultaneously introduced into the reactor at a flow rate ratio of salt:alkali:ammonia ≈ 2:1:0.3~0.5. The feed flow rate of the mixed metal salt solution is 3 L / h. The ammonia value of the reaction system is controlled at 0.40~0.80 g / L, pH=12.2~12.3 / 25℃, and the reaction continues until the precursor particle D50 reaches 1.70~2.00 μm.

[0057] Growth stage: The salt solution flow rate was uniformly restored to the growth stage set flow rate of 6 L / h within 5 hours. Simultaneously, a 2.0 mol / L mixed salt solution (with a molar ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 1:1:4), a 4 mol / L sodium hydroxide solution, and a 6.0 g / L ammonia solution were introduced at a flow rate ratio of salt:alkali:ammonia ≈ 2:1:0.3~0.5. Nitrogen gas was introduced throughout the process to maintain the ammonia concentration at 0.50~0.80 g / L, pH = 11.4~11.80 at 25℃. The reaction was continued for 100 hours, and feeding was stopped when the particle size D50 was measured to be 2.50~3.00 μm.

[0058] Aging and Post-treatment: Under nitrogen protection, the stirring speed was reduced to 400 rpm, and the mixture was aged for 3 hours. The slurry was then filtered and washed twice with 1.50 mol / L NaOH solution at 75°C and hot pure water at 75°C, following an alkali-water-alkali-water sequence, using 5 times and 35 times the dry weight of the slurry, respectively. The filter cake was vacuum dried at 120°C under a nitrogen atmosphere for at least 12 hours until the moisture content was <0.30%, yielding the precursor P1Ni. 16.67 Co 16.67 Mn 66.66 (OH)2.

[0059] Comparative Example 1 Preparation of precursor CP1 Add 80 L of pure water to the reactor, purge with nitrogen for protection, and start stirring at 900 rpm. Add 100 g / L ammonia solution to adjust the ammonia value of the bottom solution to 0.60 g / L, and add 420 g / L sodium hydroxide solution to adjust the pH to 12.10 / 25℃. Control the temperature at 50℃.

[0060] Nucleation stage: A 2.0 mol / L mixed salt solution (with a molar ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 1:1:4), a 4 mol / L sodium hydroxide solution, and a 6.0 g / L ammonia solution are simultaneously introduced into the reactor at a ratio of salt flow: alkali flow: ammonia flow ≈ 2:1:0.3~0.5. The feed flow rate of the mixed metal salt solution is 6 L / h. The ammonia value of the reaction system is controlled at 0.40~0.80 g / L, pH=12.0~12.3 / 25℃, and the reaction continues until the precursor particle D50 reaches 1.70~2.00 μm.

[0061] Growth stage: The salt solution flow rate was set to 6 L / h, and a mixed salt solution (with a molar ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 1:1:4), a 4 mol / L sodium hydroxide solution, and a 6.0 g / L ammonia solution were simultaneously introduced at a flow rate ratio of salt:alkali:ammonia ≈ 2:1:0.3~0.5. Nitrogen gas was introduced throughout the process to maintain the ammonia concentration at 0.50~0.80 g / L, pH = 11.4~11.80 at 25℃, and the reaction was continued for 100 h. Feeding was stopped when the particle size D50 was measured to be 2.50~3.00 μm.

[0062] Aging and Post-treatment: Under nitrogen protection, the stirring speed was reduced to 400 rpm, and the mixture was aged for 3 hours. The slurry was then filtered and washed twice with a 1.50 mol / L NaOH solution at 75°C and hot pure water at 75°C, following an alkali-water-alkali-water sequence, using 5 times and 35 times the dry weight of the slurry, respectively. The filter cake was vacuum dried at 120°C under a nitrogen atmosphere for at least 12 hours until the moisture content was <0.30%, yielding the precursor CP1.

[0063] Comparative Example 2 Preparation of precursor CP2 Add 80 L of pure water to the reactor, purge with nitrogen for protection, and start stirring at 900 rpm. Add 100 g / L ammonia solution to adjust the ammonia value of the bottom solution to 0.60 g / L, and add 420 g / L sodium hydroxide solution to adjust the pH to 12.10 / 25℃. Control the temperature at 50℃.

[0064] Nucleation stage: A 2.0 mol / L mixed salt solution (with a molar ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 1:1:4), a 4 mol / L sodium hydroxide solution, and a 6.0 g / L ammonia solution are simultaneously introduced into the reactor at a ratio of salt flow: alkali flow: ammonia flow ≈ 2:1:0.3~0.5. The feed flow rate of the mixed metal salt solution is 3 L / h. The ammonia value of the reaction system is controlled at 0.40~0.80 g / L, pH=12.0~12.3 / 25℃, and the reaction continues until the precursor particle D50 reaches 1.70~2.00 μm.

[0065] Growth stage: Within 5 hours, restore the salt solution flow rate to the set flow rate of 6 L / h for the growth period. Simultaneously introduce a 2.0 mol / L mixed salt solution (with a molar ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 1:1:4) along with a 4 mol / L sodium hydroxide solution and a 6.0 g / L ammonia solution at a flow rate ratio of approximately 2:1:0.3~0.5. Nitrogen gas is introduced throughout the process to maintain an ammonia concentration of 0.50~0.80 g / L, pH ≤ 12.3, and 25℃. Continue the reaction for 135~145 hours, stopping the feed when the particle size D50 reaches 2.50~3.00 μm.

[0066] Aging and Post-treatment: Under nitrogen protection, the stirring speed was reduced to 400 rpm, and the mixture was aged for 3 hours. The slurry was then filtered and washed twice with a 1.50 mol / L NaOH solution at 75°C and hot pure water at 75°C, following an alkali-water-alkali-water sequence, using 5 times and 35 times the dry weight of the washed slurry, respectively. The filter cake was vacuum dried at 120°C under a nitrogen atmosphere for at least 12 hours until the moisture content was <0.30%, yielding the precursor CP2.

[0067] Comparative Example 3 Preparation of precursor CP3 Add 80 L of pure water to the reactor, purge with nitrogen for protection, and start stirring at 900 rpm. Add 100 g / L ammonia solution to adjust the ammonia value of the bottom solution to 0.60 g / L, and add 420 g / L sodium hydroxide solution to adjust the pH to 12.10 / 25℃. Control the temperature at 50℃.

[0068] Nucleation stage: A 2.0 mol / L mixed salt solution (with a molar ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 1:1:4), a 4 mol / L sodium hydroxide solution, and a 6.0 g / L ammonia solution are simultaneously introduced into the reactor at a ratio of salt flow: alkali flow: ammonia flow ≈ 2:1:0.3~0.5. The feed flow rate of the mixed metal salt solution is 3 L / h. The ammonia value of the reaction system is controlled at 0.40~0.80 g / L, pH=11~11.4 / 25℃, and the reaction continues until the precursor particle D50 reaches 1.70~2.00 μm.

[0069] Growth stage: Within 5 hours, the salt solution flow rate was uniformly restored to the growth stage set flow rate of 6 L / h. Simultaneously, a 2.0 mol / L mixed salt solution (with a molar ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 1:1:4), a 4 mol / L sodium hydroxide solution, and a 6.0 g / L ammonia solution were introduced at a flow rate ratio of salt:alkali:ammonia ≈ 2:1:0.3~0.5. Nitrogen gas was introduced throughout the process, maintaining an ammonia concentration of 0.50~0.80 g / L, pH 11.4~11.80 at 25℃. The reaction continued for 24~26 hours, and feeding was stopped when the particle size D50 was measured to be 2.50~3.00 μm.

[0070] Aging and Post-treatment: Under nitrogen protection, the stirring speed was reduced to 400 rpm, and the mixture was aged for 3 hours. The slurry was then filtered and washed twice with a 1.50 mol / L NaOH solution at 75°C and hot pure water at 75°C, following an alkali-water-alkali-water sequence, using 5 times and 35 times the dry weight of the slurry, respectively. The filter cake was vacuum-dried at 120°C under a nitrogen atmosphere for at least 12 hours until the moisture content was <0.30%, yielding the precursor CP3.

[0071] Figure 1 Here is a SEM image of the precursor obtained in Example 1; Figure 2 Here is a SEM image of the precursor obtained in Comparative Example 1; Figure 3 Here is a SEM image of the precursor obtained in Comparative Example 2; Figure 4 The image shows the SEM image of the precursor obtained in Comparative Example 3.

[0072] Depend on Figures 1-4 It can be seen that as the pH decreases and the reaction time decreases during the nucleation stage, the amount of nucleation decreases, leading to faster growth, which in turn results in thinner primary particles and relatively larger pores.

[0073] Cathode material preparation and battery testing Precursors P1 / CP1 / CP2 / CP3 were mixed with lithium carbonate (Li2CO3) at a lithium to transition metal molar ratio n(Li) / n(TM) = 1.40, and a dopant of 0.5% (by mass of the precursor materials) was added. The dopant type was MgO + Al2O3 + TiO2 (mass ratio of MgO, Al2O3, and TiO2 was 3:1:1). Under an oxygen atmosphere, the temperature was first increased to 500℃ at 3℃ / min and held for 5 h, then increased to 900℃ at 5℃ / min and held for 12 h. After cooling, 0.50% Nb2O5 / Ta2O5 / ZrO2 was added for coating, and then heat-treated at 600℃ for 6 h to obtain the final cathode material C1 / CC1 / CC2 / CC3.

[0074] Electrochemical performance testing: The above-mentioned positive electrode material, conductive carbon black, and binder PVDF were mixed in a mass ratio of 90:5:5 to form a slurry, which was then coated onto aluminum foil. After drying and rolling, a positive electrode sheet was formed with a positive electrode areal density of 58 mg / cm³. 3 A CR2032 coin cell was assembled using lithium metal sheets as the negative electrode.

[0075] Testing System: Activation: Perform the first charge and discharge at a rate of 0.1C (1C = 250 mA / g) within a voltage range of 2.0 V to 4.8 V.

[0076] Cycling: Starting from week 2, constant current charge-discharge cycle tests were performed at a 1C rate within a voltage range of 2.0 V to 4.6 V.

[0077] Test results: Table 1. Characterization and electrical properties of precursor materials

[0078] Note: Primary particle thickness (nm): The average of the thicknesses of 10 primary particles of the same secondary particle.

[0079] The results show that, under the same testing standards, the cathode material provided by this invention outperforms the comparative sample in terms of capacity, compaction density, and cycle life. In particular, the compaction density and tap density of the cathode material exceed the limits of conventional samples. Furthermore, while thicker primary particles would normally result in a decrease in capacity, the capacity of this invention is improved.

[0080] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nickel-cobalt-manganese ternary hydroxide, characterized in that, The preparation method is carried out in a protective gas atmosphere and includes the following steps: The metal salt solution, precipitant solution, and complexing agent solution were respectively introduced into the bottom liquid for mixing. Then, the resulting system underwent precipitation reaction and post-treatment to obtain the nickel-cobalt-manganese ternary hydroxide. The metal salts in the metal salt solution are nickel salts, cobalt salts, and manganese salts; The precipitation reaction includes nucleation, growth, and aging occurring sequentially. At 25°C, the pH value of the system during nucleation is 11.5~12.5, and the pH value of the system during growth is 11~12; The flow rate of the metal salt solution during nucleation is 40-60% of the flow rate of the metal salt solution during growth.

2. The preparation method according to claim 1, characterized in that, The concentration of the metal salt in the metal salt solution is 1.5~2.5 mol / L; The nickel salt includes one or both of nickel sulfate and nickel acetate; the cobalt salt includes one or both of cobalt sulfate and cobalt acetate; the manganese salt includes one or both of manganese sulfate and manganese acetate.

3. The preparation method according to claim 1, characterized in that, The complexing agent solution includes one or more of ammonia water, ammonium sulfate solution, ammonium chloride solution, and ethylenediamine solution; The concentration of the complexing agent solution is 0.2~20 g / L.

4. The preparation method according to claim 1 or 3, characterized in that, The precipitant solution includes NaOH solution; the concentration of the precipitant solution is 4~10.5 mol / L.

5. The preparation method according to claim 1, characterized in that, The ammonia value of the base solution is 0.2~2.0 g / L, and the pH value is 11.5~12.5 / 25℃.

6. The preparation method according to claim 1, characterized in that, During the nucleation process, the flow rate ratio of the metal salt solution, precipitant solution, and complexing agent solution is 2:1:0.3~0.

5.

7. The preparation method according to claim 1, characterized in that, The precipitation reaction is carried out at a temperature of 40~60℃; During the nucleation process, the ammonia value of the system is 0.2~1.2 g / L, the time is 20~70h, and the D50 of the particles obtained by the nucleation process is 1.3~2.0 μm. During the growth process, the flow rate ratio of the metal salt solution, precipitant solution, and complexing agent solution is 2:0.9~1.1:0.3~0.5, the hourly inflow of the metal salt solution is 5~10% of the effective volume of the reactor, and the ammonia value of the system is 0.2~2g / L. The growth period is 30-200 hours. The D50 of the particles obtained from the growth is 2.3~5.6 μm.

8. The nickel-cobalt-manganese ternary hydroxide prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The chemical composition is Ni a Co b Mn c (OH)₂, 0.10≤a≤0.50, 0.00<b≤0.40, 0.50≤c≤0.80, D50 is 2.3~5.7μm, tap density ≥1.45g / cm³ 3 BET specific surface area ≤ 22.00 m² 2 / g; The nickel-cobalt-manganese ternary hydroxide is an aggregate of lamellar particles with an average thickness > 220 nm.

9. A lithium-rich manganese-based cathode material, characterized in that, The raw materials for preparation include the nickel-cobalt-manganese ternary hydroxide as described in claim 8, a lithium source, a dopant, and a coating agent.

10. A lithium-ion battery, characterized in that, The positive electrode of the lithium-ion battery comprises the lithium-rich manganese-based positive electrode material as described in claim 9.

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