Ternary positive electrode material precursor, preparation method and application thereof

Abstract

The application provides a ternary positive electrode material precursor, a preparation method and application thereof. The ternary positive electrode material precursor is a spherical secondary particle with a core-shell structure, and the core-shell structure comprises a precursor core and a precursor shell. The precursor core comprises a nickel-cobalt-manganese carbonate, and the precursor shell comprises a nickel-cobalt-manganese hydroxide primary particle. The surface of the nickel-cobalt-manganese hydroxide primary particle is loaded with ion conductive particles. The ternary positive electrode material precursor of the application adopts a core-shell structure, which can promote the formation of a local lithiumation reaction environment when the precursor is subjected to a high-temperature solid-phase reaction with coarse lithium hydroxide, and the ion conductive particles on the surface of the shell can significantly improve the migration rate of lithium ions at the solid-phase interface, thereby achieving uniform distribution of lithium elements in the precursor particles and significantly improving the cycle life, rate performance and low-temperature resistance of lithium batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium battery materials technology, and more specifically, to a ternary cathode material precursor, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, as efficient and clean energy storage devices, are widely used in electric vehicles, consumer electronics, and energy storage systems. Among them, ternary cathode materials (such as NCM and NCA) have become a research hotspot due to their high energy density and good overall performance. However, their large-scale industrial production still faces many challenges, especially in balancing low cost and high performance during material preparation.

[0003] Currently, the preparation of ternary cathode materials typically involves a high-temperature solid-state reaction between hydroxide or carbonate precursors and a lithium source (such as lithium hydroxide or lithium carbonate). However, traditional methods require high particle size and purity of the lithium source, necessitating the use of fine-particle, high-purity lithium hydroxide to ensure uniform lithiation, significantly increasing production costs. Furthermore, coarse-particle lithium hydroxide, due to its long diffusion path and low reactivity, easily leads to uneven lithiation, thus affecting the electrochemical performance of the material, such as capacity decay, reduced cycle life, and decreased rate performance.

[0004] To address the issue of lithiation uniformity, existing technologies typically employ nanoscale lithium sources, liquid-phase assisted sintering, or multiple calcination processes. However, these methods are complex, energy-intensive, and unsuitable for industrial production. Furthermore, inert phases (such as rock salt phases) tend to form on the surface of cathode materials after high-temperature sintering, hindering lithium-ion diffusion and affecting rate performance and low-temperature power characteristics. Although coating the surface with a fast-ion conductor layer (such as Li₂ZrO₃ or Li₃PO₄) can improve interfacial ion transport, the additional coating step increases process complexity.

[0005] Therefore, there is an urgent need to develop a precursor structure that enables simple and efficient preparation of ternary cathode materials in order to solve the above-mentioned technical problems. Summary of the Invention

[0006] The main objective of this invention is to provide a ternary cathode material precursor, its preparation method, and its application, in order to solve the problem of uneven lithiation inside the ternary cathode material caused by the low lithium diffusion rate when using a ternary cathode material precursor in the preparation of ternary cathode materials with coarse-particle lithium hydroxide.

[0007] To achieve the above object, according to one aspect of the present invention, a ternary cathode material precursor is provided, which is a spherical secondary particle with a core-shell structure. The core-shell structure includes a precursor inner core and a precursor outer shell; wherein, the precursor inner core includes nickel cobalt manganese carbonate; the precursor outer shell includes primary particles of nickel cobalt manganese hydroxide; ion conductive particles are loaded on the surface of the primary particles of nickel cobalt manganese hydroxide, and the ion conductive particles contain metal elements.

[0008] Further, the chemical formula of the ternary cathode material precursor is Ni x , z , x , y , y , z Co y Mn z (OH)2M@Ni x Co y Mn z CO3, where 0.6 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, M is one or more of Ni, Co, Mn, W, Al, Mg, Ca; and / or, the porosity of the precursor inner core is 1.84 - 9.31%; and / or, the porosity of the precursor outer shell is 10 - 50%; and / or, in the ternary cathode material precursor, the volume percentage content of the precursor inner core is 10 - 30%; and / or, the Dv50 of the ternary cathode material precursor is 2.0 - 6.0 μm; and / or, the BET specific surface area of the ternary cathode material precursor is 5 - 30 m 2 / g; and / or, the tap density of the ternary cathode material precursor is 1.3 - 2.1 g / cm 3 ; and / or, the primary particles of nickel cobalt manganese hydroxide are formed by stacking nickel cobalt manganese hydroxide sheets. The nickel cobalt manganese hydroxide sheets have a length direction, a width direction and a thickness direction. The nickel cobalt manganese hydroxide sheets are stacked along a plane perpendicular to the length direction to form the primary particles of nickel cobalt manganese hydroxide; wherein, the size of the nickel cobalt manganese hydroxide sheets along the length direction is 160 - 200 nm, the size along the width direction is 85 - 108 nm, and the size along the thickness direction is 40 - 50 nm; and / or, the size of the primary particles of nickel cobalt manganese hydroxide along the length direction is 160 - 200 nm, the size along the width direction is 350 - 420 nm, and the size along the thickness direction is 350 - 420 nm.

[0009] Further, the chemical formula of the precursor inner core is Ni x Co y Mn z CO3, where 0.6 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3; and / or, the chemical formula of the precursor outer shell is Ni x Co y Mn z(OH)2M, where 0.6 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, and M is the metal element of the ionic conductive particles; and / or, the ratio of the size of the nickel-cobalt-manganese hydroxide primary particles to the nickel-cobalt-manganese hydroxide flakes in the thickness direction is (8 - 10):1.

[0010] According to another aspect of the present invention, there is also provided a method for preparing the above ternary cathode material precursor, including the following steps: Step S1, mixing a first precipitant solution, a complexing agent solution, and deionized water to obtain a precipitation bottom liquid; Step S2, under a protective atmosphere, introducing a nickel-manganese solution, a first ion solution, and a complexing agent solution into the precipitation bottom liquid at the same flow rate respectively, and at the same time introducing the first precipitant solution into the precipitation bottom liquid for pre-precipitation to obtain a pre-precipitation slurry; Step S3, keeping the flow rates of the nickel-manganese solution, the first ion solution, the first precipitant solution, and the complexing agent solution unchanged, and introducing the first ion solution and the second ion solution into the pre-precipitation slurry continuously and alternately at the same flow rate as the nickel-manganese solution for the first co-precipitation reaction to obtain a first precipitate and a first co-precipitation mixture, and stopping the reaction when the particle size D50 of the first precipitate is 1.5 - 2.2 μm to obtain a core slurry;

[0011] Step S4, keeping the flow rates unchanged, continuing to introduce the nickel-manganese solution, a second precipitant solution, a complexing agent solution, and the second ion solution into the core slurry, and at the same time introducing the third ion solution and the second ion solution into the core slurry continuously and alternately at the same flow rate as the nickel-manganese solution for the second co-precipitation reaction to obtain a second precipitate and a second co-precipitation mixture; stopping the reaction when the particle size D50 of the second precipitate is 2.5 - 6.0 μm to obtain a first core-shell slurry; filtering the first core-shell slurry to obtain the second precipitate, and adding the second precipitate to the second ion solution for aging to obtain a second core-shell slurry; Step S5, keeping the flow rates unchanged, continuing to introduce a complexing agent into the second core-shell slurry, and at the same time introducing a fourth ion solution into the second core-shell slurry at the same flow rate as the complexing agent for the third co-precipitation reaction to obtain a third core-shell slurry; washing and drying the third core-shell slurry in sequence to obtain the ternary cathode material precursor; the molar concentration of the first ion solution < the molar concentration of the second ion solution; the molar concentration of the second ion solution < the molar concentration of the third ion solution; the molar concentration of the fourth ion solution < the molar concentration of the first ion solution.

[0012] Further, the complexing agent solution includes one or more of ammonia, citric acid, tartrate, and EDTA; and / or, the molar concentration of the complexing agent in the complexing agent solution is 10-20 mol / L; and / or, independently, the first ionic solution, the second ionic solution, the third ionic solution, and the fourth ionic solution each include a metal salt, the metal element of which includes one or more of cobalt, nickel, manganese, tungsten, aluminum, magnesium, and calcium, and the metal salt is added in the form of one or more of sulfate, carbonate, and nitrate; and / or, in step S1, the first precipitant solution includes one or more of sodium carbonate aqueous solution, potassium carbonate aqueous solution, and ammonium carbonate aqueous solution; and / or, the weight percentage of the first precipitant in the first precipitant solution is 32-40 wt.%; and / or, the pH value of the precipitation bottom solution is 8.5-10.5; and / or, the weight concentration of the complexing agent in the precipitation bottom solution is 0.5-2.5 g / L.

[0013] Further, in step S2, the pre-precipitation time is 0.5~2h; and / or, the flow rate ratio of the first precipitant solution to the nickel-manganese solution is (0.9~1.0):1; and / or, the protective atmosphere includes nitrogen and / or argon; and / or, the sum of the molar concentrations of metal ions in the nickel-manganese solution is 1.8~2.2mol / L; and / or, the molar ratio of nickel ions to manganese ions in the nickel-manganese solution is (60~80):(10~30); and / or, the nickel-manganese solution also includes cobalt ions, and the molar ratio of nickel ions, cobalt ions, and manganese ions is (60~80):(7~10):(10~30); and / or, the molar concentration of the first ion solution is 1. The concentration of the first ion solution is 8~2.2 mol / L; and / or, in step S3, the molar concentration of the second ion solution is 2.0~2.4 mol / L; and / or, the time interval between the continuous alternating addition of the first ion solution and the second ion solution is 5~10 min; and / or, in the first coprecipitation mixture, the molar concentration of the complexing agent is 0.5~1.2 mol / L; and / or, step S3 further includes adjusting the flow rate of the first precipitant solution so that the pH value of the first coprecipitation mixture is 6.5~8.5; and / or, and / or, the first coprecipitation reaction is carried out under the first stirring, the temperature of the first stirring is 40~80℃, and the rotation speed is 300~800 rpm.

[0014] Further, in step S4, the second precipitant solution includes one or more of sodium hydroxide aqueous solution, potassium hydroxide, and calcium hydroxide; and / or, the weight percentage of the second precipitant in the second precipitant solution is 32~40 wt.%; and / or, step S4 further includes adjusting the flow rate of the second precipitant solution so that the pH value of the second coprecipitate mixture is 10.5~12.0; and / or, the time interval between the continuous alternating addition of the third ionic solution and the second ionic solution is 5~10 min; and / or, the mass concentration of the complexing agent in the second coprecipitate mixture is 0.2~0.5 g / L; and / or, the third ionic solution... The molar concentration of the fourth ion solution is 2.2~2.6 mol / L; and / or, the second coprecipitation reaction is carried out under the second stirring, the temperature of the second stirring is 40~80℃, and the rotation speed is 300~800 rpm; and / or, in step S5, the molar concentration of the fourth ion solution is 0.8~1.2 mol / L; and / or, the pH value of the third core-shell slurry is 10.5~11.5; and / or, in the third core-shell slurry, the mass concentration of the complexing agent is 0.8~1.2 g / L; and / or, the third coprecipitation reaction is carried out under the third stirring, the temperature of the third stirring is 30~90℃, the time is 1~2 h, and the rotation speed is 800~1200 rpm.

[0015] According to another aspect of the present invention, a ternary cathode material is also provided, wherein the raw materials of the ternary cathode material include the above-mentioned ternary cathode material precursor.

[0016] According to another aspect of the present invention, a method for preparing the above-mentioned ternary cathode material is also provided, comprising the following steps: mixing a ternary cathode material precursor with lithium hydroxide, and performing a first sintering and a second sintering sequentially to obtain a ternary cathode material, wherein the particle size Dv50 of the lithium hydroxide is 200~800μm.

[0017] According to another aspect of the present invention, a positive electrode sheet is also provided, comprising a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, wherein the positive active material layer comprises the ternary positive electrode material described above.

[0018] According to another aspect of the present invention, a lithium-ion battery is also provided, comprising the above-described positive electrode.

[0019] Applying the technical solution of this invention, the ternary cathode material precursor adopts a core-shell structure with spherical secondary particles. Its core is composed of nickel-cobalt-manganese carbonate, and its shell is assembled from nickel-cobalt-manganese hydroxide primary particles. Ion-conducting particles are loaded on the surface of the hydroxide primary particles. This structure enables the carbonate in the core to decompose and generate carbon dioxide gas during high-temperature solid-phase reaction with coarse-particle lithium hydroxide, which locally promotes the formation of the lithiation reaction environment. At the same time, the ion-conducting particles on the shell surface can significantly improve the migration rate of lithium ions at the solid-phase interface, thereby achieving uniform distribution of lithium elements in the precursor particles and significantly improving the cycle life, rate performance, and low-temperature performance of the lithium battery. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 A cross-sectional view of a ternary cathode material precursor according to Embodiment 1 of the present invention is shown;

[0022] Figure 2 A cross-sectional view of the core of a ternary cathode material precursor according to Embodiment 1 of the present invention is shown;

[0023] Figure 3 A morphology diagram of the ternary cathode material precursor according to Embodiment 1 of the present invention is shown;

[0024] Figure 4 A morphology diagram of the first sintered product according to Embodiment 1 of the present invention is shown;

[0025] Figure 5 The morphology of the ternary cathode material precursor according to Comparative Example 1 is shown;

[0026] Figure 6 The morphology diagram of the sintered product according to Comparative Example 1 is shown. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] As described in the background section of this invention, existing technologies suffer from uneven lithiation within the ternary cathode material due to the low lithium diffusion rate when the ternary cathode material precursor is prepared with coarse-grained lithium hydroxide. To address this issue, in a typical embodiment of this invention, a ternary cathode material precursor is provided. The ternary cathode material precursor is a core-shell structured spherical secondary particle, comprising a precursor core and a precursor shell. The precursor core comprises nickel-cobalt-manganese carbonate; the precursor shell comprises nickel-cobalt-manganese hydroxide primary particles; and the surface of the nickel-cobalt-manganese hydroxide primary particles is loaded with ionic conductivity particles, which contain metal elements.

[0029] In the ternary cathode material precursor, nickel cobalt manganese carbonate serves as the precursor core, while primary nickel cobalt manganese hydroxide particles loaded with ionic conductivity particles on the surface agglomerate to form the precursor shell. The precursor core is coated with the precursor shell, forming spherical secondary particles with a core-shell structure.

[0030] The ternary cathode material precursor adopts core-shell structured spherical secondary particles. Its core is nickel-cobalt-manganese carbonate, and its outer shell consists of primary nickel-cobalt-manganese hydroxide particles, with ionicly conductive particles loaded on the surface of these primary hydroxide particles. This structure significantly improves the electrochemical performance of the ternary cathode material obtained through sintering. During high-temperature solid-state lithiation (i.e., sintering) with existing coarse-grained lithium hydroxide (particle size D50 of 200~800μm), the carbon dioxide generated by the thermal decomposition of the precursor's core carbonate can locally promote the in-situ formation of lithium carbonate on the surface, reducing the lithium-ion diffusion hindrance caused by the large size of the lithium source particles. Simultaneously, the ionicly conductive particles loaded on the outer shell provide active sites for lithium ions, promoting the in-situ construction of a lithium-ion conductor layer by lithium carbonate. This significantly improves the migration rate and uniformity of lithium ions on the precursor particle surface and at grain boundaries, effectively overcoming the problem of uneven lithiation caused by the large particle size and low reactivity of coarse-grained lithium hydroxide.

[0031] The aforementioned structure of the ternary cathode material precursor can achieve uniform distribution of lithium elements within the particles without relying on fine-particle lithium sources or complex processes, thereby improving the structural integrity and electrochemical performance of the cathode material. It can provide a higher-performance precursor material for the large-scale preparation of high-nickel ternary cathode materials under low-cost and high-safety lithium source conditions.

[0032] In a preferred embodiment, the chemical formula of the ternary cathode material precursor is Ni. x Co y Mn z (OH)2M@Ni x Co y Mn zCO3, where 0.6 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, M is one or more of Ni, Co, Mn, W, Al, Mg, Ca; and / or, the porosity of the inner core of the precursor is 1.84 - 9.31%; and / or, the porosity of the outer shell of the precursor is 10 - 50%; and / or, in the ternary cathode material precursor, the volume percentage content of the inner core of the precursor is 10 - 30%; and / or, the Dv50 of the ternary cathode material precursor is 2.0 - 6.0 μm; and / or, the BET specific surface area of the ternary cathode material precursor is 5 - 30 m 2 / g; and / or, the tap density of the ternary cathode material precursor is 1.3 - 2.1 g / cm 3 .

[0033] For the precursor of the ternary cathode material with the above chemical formula, the proportion of each element is limited within the above range, which is beneficial to further optimize the balance among the structural stability, lithium ion diffusion kinetics and thermal safety of the material, so that it is easier to realize the formation of high-performance cathode materials under the conditions of low-cost coarse-grained lithium hydroxide lithiation. Among them, M represents the element of the ion-conducting particles loaded on the surface of the primary particles of nickel-cobalt-manganese hydroxide. The above types of ion-conducting particles are more conducive to providing a higher conduction network for lithium ions, and further promoting the defects of slow diffusion rate and uneven migration of coarse-grained lithium hydroxide in the subsequent preparation process of the cathode material. Loading the ion-conducting particles on the primary particles of nickel-cobalt-manganese hydroxide to form intergranular defects between the primary particles is more conducive to the formation of an ion conduction network in the outer shell of the precursor, and further improves the migration rate and uniformity of lithium ions on the surface and grain boundaries of the precursor particles.

[0034] Controlling the porosity of the inner core of the precursor within the above range is more helpful for the effective diffusion of carbon dioxide gas generated by subsequent sintering to the voids of the precursor, promoting the in-situ generation of lithium carbonate intermediate phase in the voids of the precursor and the preliminary penetration of lithium ions. Limiting the size of the primary particles of nickel-cobalt-manganese hydroxide in the thickness direction within the above range further shortens the diffusion path of lithium ions migrating from the surface to the inner core and improves the transmission efficiency of the ion transport network. The outer shell porosity within the above range is more conducive to the formation of a high-porosity layered channel structure in the outer shell, significantly increasing the reaction interface area and shortening the lithium ion diffusion path. Limiting the volume percentage content of the inner core of the precursor within the above range is more conducive to the coordinated improvement of lithium diffusion path optimization and the structural stability of the cathode material during subsequent lithiumation sintering. Limiting the particle size, specific surface area and tap density of the ternary cathode material precursor within the above range is more conducive to balancing the moderate particle size, sufficient surface active sites and reasonable particle packing density of the ternary cathode material precursor, thereby further improving the uniformity and mass transfer efficiency of the contact between coarse-grained lithium hydroxide and the precursor during solid-phase lithiation.

[0035] In some embodiments, the primary nickel-cobalt-manganese hydroxide particles are formed by stacking nickel-cobalt-manganese hydroxide sheets. The nickel-cobalt-manganese hydroxide sheets have a length direction, a width direction, and a thickness direction. The nickel-cobalt-manganese hydroxide sheets are stacked perpendicular to the plane where the length direction is located to form the primary nickel-cobalt-manganese hydroxide particles. Among them, the size of the nickel-cobalt-manganese hydroxide sheets in the length direction is 160-200 nm, the size in the width direction is 85-108 nm, and the size in the thickness direction is 40-50 nm; and / or, the size of the primary nickel-cobalt-manganese hydroxide particles in the length direction is 160-200 nm, the size in the width direction is 350-420 nm, and the size in the thickness direction is 350-420 nm.

[0036] The primary nickel-cobalt-manganese hydroxide particles are formed by stacking sheet-like structures. Since the stacked nickel-cobalt-manganese hydroxide sheets have a high active exposure surface, it is more conducive to the uniform diffusion of lithium ions, improving the migration efficiency of lithium ions, and further improving the electrochemical performance of the battery. In some embodiments, the curvature of the precursor shell is 0.031-0.245.

[0037] To further improve the balance of the precursor core-shell structure, be more conducive to the uniform diffusion of lithium ions, and improve the migration efficiency of lithium ions. In some embodiments, the porosity of the precursor inner core is 4.85-5.92%; and / or, the porosity of the precursor shell is 17.2-28%; and / or, in the ternary cathode material precursor, the volume percentage content of the precursor inner core is 17.2-28%; and / or, ionic conductive particles are loaded on the surface of the primary nickel-cobalt-manganese hydroxide particles; and / or, the Dv50 of the ternary cathode material precursor is 3.2-3.85 μm; and / or, the tap density of the ternary cathode material precursor is 1.76-1.94 g / cm 3 .

[0038] In a preferred embodiment, the chemical formula of the precursor inner core is Ni x Co y Mn z CO3, where 0.6 ≤ x ≤ 0.7, 0.05 ≤ y ≤ 0.1, 0 < z < 0.3; and / or, the chemical formula of the precursor shell is Ni x Co y Mn z (OH)2M, where 0.6 ≤ x ≤ 0.7, 0.05 ≤ y ≤ 0.1, 0 < z < 0.3, and M is the metal element of the ionic conductive particles; and / or, the ratio of the size of the primary nickel-cobalt-manganese hydroxide particles to the size of the nickel-cobalt-manganese hydroxide sheets in the thickness direction is (8-10):1.

[0039] Stacking nickel-cobalt-manganese hydroxide sheets with the aforementioned thickness-direction dimension ratio creates a high-porosity, low-curvature interlayer channel network, which is more conducive to electrolyte penetration and rapid lithium-ion diffusion during charge and discharge, significantly improving the material's rate performance and low-temperature power characteristics. Simultaneously, this thickness-direction dimension ratio range effectively suppresses excessive agglomeration and abnormal grain growth during sintering, better maintaining the integrity of the core-shell structure, thereby extending cycle life and reducing the risk of interfacial side reactions.

[0040] In another typical embodiment of the present invention, a method for preparing the above-mentioned ternary cathode material precursor is also provided, comprising the following steps: Step S1, mixing a first precipitant solution, a complexing agent solution, and deionized water to obtain a precipitate base solution; Step S2, under a protective atmosphere, introducing a nickel-manganese solution and a first ion solution into the precipitate base solution at the same flow rate, while simultaneously introducing the first precipitant solution and the complexing agent solution into the precipitate base solution for preprecipitation to obtain a preprecipitate slurry; Step S3, keeping the flow rates of the nickel-manganese solution, the first ion solution, the first precipitant solution, and the complexing agent solution constant, continuously and alternately introducing the first ion solution and the second ion solution into the preprecipitate slurry at the same flow rate as the nickel-manganese solution to carry out a first coprecipitation reaction to obtain a first precipitate, obtaining a first coprecipitate mixture, stopping the reaction when the particle size D50 of the first precipitate is 1.5~2.2μm to obtain a core slurry.

[0041] Step S4: Maintaining a constant flow rate, continue to introduce nickel-manganese solution, second precipitant solution, complexing agent solution, and second ion solution into the core slurry. Simultaneously, alternately introduce the third ion solution and the second ion solution at the same flow rate as the nickel-manganese solution to carry out the second coprecipitation reaction, obtaining the second precipitate and a second coprecipitate mixture. Stop the reaction when the particle size D50 of the second precipitate is 2.5~6.0 μm, obtaining the first core-shell slurry. Filter the first core-shell slurry to obtain the second precipitate, and add the second ion solution for aging. A second core-shell slurry is obtained; in step S5, while keeping the flow rate constant, a complexing agent is continuously introduced into the second core-shell slurry, and a fourth ion solution is introduced at the same flow rate as the complexing agent to carry out the third coprecipitation reaction, thereby obtaining a third core-shell slurry; the third core-shell slurry is washed and dried sequentially to obtain a ternary cathode material precursor; the molar concentration of the first ion solution is less than the molar concentration of the second ion solution; the molar concentration of the second ion solution is less than the molar concentration of the third ion solution; the molar concentration of the fourth ion solution is less than the molar concentration of the first ion solution.

[0042] First, the first precipitant solution, complexing agent solution, and deionized water are mixed to obtain a precipitation base solution. Under a protective atmosphere, the nickel-manganese solution, the first ion solution, and the complexing agent solution are introduced into the precipitation base solution at the same flow rate, while the first precipitant solution is introduced simultaneously for pre-precipitation. Pre-precipitation provides a large number of fine, uniform, and consistent growth sites (crystal nuclei) for the subsequent stepwise precipitation reaction, ensuring that the final product particles have a concentrated particle size distribution, regular morphology, and high tap density, and effectively avoiding component segregation caused by homogeneous nucleation lag, resulting in a pre-precipitated slurry. The first ion solution and the second ion solution are continuously and alternately added to the pre-precipitated slurry at the same flow rate as the nickel-manganese solution. During the core formation stage, a lower concentration of the first ion solution is alternately added with a medium concentration of the second ion solution. Since different cobalt concentrations have different precipitation rates, cobalt can be selectively deposited at the grain boundaries of the basic carbonate core, forming a micro-defect structure, enhancing the connectivity of the subsequent lithium-ion diffusion path, and carrying out the first co-precipitation reaction to obtain the core slurry.

[0043] The reaction is carried out by continuously and alternately introducing the first ion solution and the second ion solution. The first ion solution can be introduced first, or the second ion solution can be introduced first. The reaction is stopped when the particle size D50 of the first precipitate is 1.5~2.2μm.

[0044] Then, while keeping the flow rate constant, nickel-manganese solution, second precipitant solution, complexing agent solution, and second ion solution are continuously introduced into the core slurry. At the same time, third ion solution and second ion solution are continuously and alternately added at the same flow rate as nickel-manganese solution. During the shell growth stage, a higher concentration of third ion solution is used to work synergistically with the second ion solution. Different concentrations of conductive ions result in different precipitation rates. On the one hand, the same concentration of nickel-manganese solution synergistically co-precipitates with the nickel-manganese solution. On the other hand, the high concentration of excess conductive ions will precipitate onto the particle surface, thereby forming active sites and guiding the lithiation process of crude lithium. This promotes the directional stacking of hydroxide nanosheets and the construction of interconnected channels, and carries out the second co-precipitation reaction to obtain the first core-shell slurry.

[0045] The reaction is carried out by continuously and alternately introducing the third ion solution and the second ion solution. The third ion solution can be introduced first, or the second ion solution can be introduced first. The reaction is stopped when the particle size D50 of the second precipitate is 2.5~6.0μm.

[0046] Finally, while keeping the flow rate constant, continue to introduce the second core-shell slurry complexing agent, and at the same flow rate, introduce the fourth ion solution. Introducing the fourth ion solution with the lowest concentration in the final coating stage enables the conductive ions to form a protective layer on the particle surface, which helps to protect the electrical performance of the subsequent cathode material, improve power and low-temperature performance, and carry out the third co-precipitation reaction to achieve uniform loading of high ionic conductivity particles on the shell surface, thus obtaining the third core-shell slurry.

[0047] The use of four ionic solutions of different concentrations creates a gradient precipitation process for cobalt. A slight excess of cobalt precipitates on the surface of the primary particles, forming intergranular defects between the primary particles within the outer shell pores. In the core region, slow deposition of the low-concentration ionic solution creates a slight excess of cobalt within the grains, constructing defect channels conducive to lithium-ion diffusion. The intermediate layer grows rapidly and accumulates at the interface under the influence of the high-concentration ionic solution, enhancing structural stability. The outermost layer is uniformly covered by a thin layer formed by an extremely low-concentration fourth ionic solution, suppressing surface side reactions. This concentration gradient design, synergistically with the co-precipitation process, effectively solves the problem of high diffusion resistance and incomplete lithiation caused by uneven cobalt distribution during the subsequent lithiation of coarse-grained lithium hydroxide, significantly improving the lithiation uniformity and electrochemical performance of the material.

[0048] This invention, by gradient-controlled sequential and alternating feeding of ion solutions, not only minimizes the hindrance in lithiation reaction caused by uneven ion distribution in traditional processes, but also provides an in-situ ion transport channel for the subsequent high-temperature solid-state reaction of coarse-particle lithium hydroxide without relying on external coating agents. This significantly improves the diffusion uniformity and reaction efficiency of the lithium source, while maintaining the high tap density and structural stability of the precursor. Compared with conventional processes, this invention solves the problem of uneven diffusion when using low-cost coarse-particle lithium hydroxide as a lithium source. During the molten lithiation process, it can increase the lithium diffusion rate, enabling uniform lithiation and laying the structural foundation for obtaining ternary cathode materials with high consistency and high rate performance through subsequent sintering.

[0049] In a preferred embodiment, the complexing agent solution includes one or more of ammonia, citric acid, tartrate, and EDTA (ethylenediaminetetraacetic acid); and / or, the molar concentration of the complexing agent in the complexing agent solution is 10-20 mol / L; independently, the first ionic solution, the second ionic solution, the third ionic solution, and the fourth ionic solution each include a metal salt, the metal element of which includes one or more of cobalt, nickel, manganese, tungsten, aluminum, magnesium, and calcium, and the metal salt is added in the form of one or more of sulfate, carbonate, and nitrate.

[0050] The aforementioned complexing agents can further promote the stable dissolution and uniform coordination of metal ions. Limiting the molar concentration of the complexing agent within the aforementioned range makes it easier to control the complexation equilibrium of the reaction system, avoiding premature precipitation or metal ion release, thus more conducive to the formation of a uniform core-shell structure precursor. The aforementioned first precipitant solutions can further reduce particle aggregation caused by local pH abrupt changes. Limiting the weight percentage of the first precipitant solution within the aforementioned range makes it easier to achieve mild and continuous carbonate ion release, which is more conducive to the slow nucleation of the basic complex carbonate core and the development of its pore structure.

[0051] All of the above-mentioned metal elements can be precipitated in the precursor core and shell. When the metal element is cobalt, nickel, or manganese, the metal element is deposited on the surface of the precipitate as ionic conductivity particles in a small excess form on the basis of the co-precipitation reaction. When the metal element is not cobalt, nickel, or manganese, the metal element does not co-precipitate with cobalt, nickel, or manganese, but is directly deposited on the surface of the primary particles of nickel cobalt manganese hydroxide as ionic conductivity particles.

[0052] In a preferred embodiment, in step S1, the first precipitant solution includes one or more of sodium carbonate aqueous solution, potassium carbonate aqueous solution, and ammonium carbonate aqueous solution; and / or, the weight percentage of the first precipitant in the first precipitant solution is 32~40 wt.%; and / or, the pH value of the precipitation bottom solution is 8.5~10.5; and / or, the weight percentage of the complexing agent in the precipitation bottom solution is 1.5~3.5 g / L; and / or, the mass concentration of the first precipitant in the precipitation bottom solution is 0.5~2.5 g / L.

[0053] The pH value of the precipitation substrate within the above range can further inhibit the non-selective precipitation of metal hydroxides. This range is more favorable for the preferential formation of carbonate precursors rather than hydroxides than traditional alkaline substrates. When the weight percentage of the complexing agent in the precipitation substrate is within the above range, it can make it easier to maintain the solubility stability of metal ions, while avoiding gradient imbalance caused by excessive ammonia volatilization to a greater extent. When the mass concentration of the first precipitant in the precipitation substrate is within the above range, it can further reduce the initial nucleation rate, which is more conducive to the formation of uniformly sized and densely structured nuclei.

[0054] In a preferred embodiment, in step S2, the pre-precipitation time is 0.5~2h; and / or, the flow rate ratio of the first precipitant solution to the nickel-manganese solution is (0.9~1.0):1; and / or, the protective atmosphere includes nitrogen and / or argon; and / or, the sum of the molar concentrations of metal ions in the nickel-manganese solution is 1.8~2.2mol / L; and / or, the molar ratio of nickel ions to manganese ions in the nickel-manganese solution is (60~70):28; and / or, the nickel-manganese solution also includes cobalt ions, and the molar ratio of nickel ions, cobalt ions and manganese ions is (60~70):(5~10):28; and / or, the molar concentration of the first ion solution is 1.8~2.2mol / L; and / or, the molar concentration of the second ion solution is 2.0~2.4mol / L.

[0055] The aforementioned protective atmosphere can further promote the structural stability of the precursor during co-precipitation, reduce lattice distortion caused by surface oxidation or localized alkaline corrosion, and better maintain the pore integrity of the basic carbonate core. Limiting the molar concentration of the nickel-manganese solution to the above range can further promote the synergistic control of the precipitation reaction rate and nucleation density, which is more conducive to obtaining a secondary spherical structure with uniform particle size and stable tap density.

[0056] Limiting the molar ratio of nickel to manganese ions in the nickel-manganese solution to the aforementioned range can further promote the improvement of cation order in the layered structure, reduce the risk of Jahn-Teller distortion and structural collapse during cycling caused by excessive manganese content, and better maintain the structural stability of the material under high voltage, making it easier to maintain capacity retention during long cycles. In the nickel-manganese solution, the aforementioned molar ratio of nickel, cobalt, and manganese ions can further promote the gradient distribution of cobalt at the core-shell interface, reduce the electronic conductivity imbalance caused by excessive cobalt enrichment in the shell, and better induce the selective deposition of high ionic conductivity particles at primary grain boundaries, making it easier to form a continuous fast ion conductor network during the pre-sintering stage, improving rate performance and low-temperature power response.

[0057] The first and second ion solutions within the aforementioned concentration range form a more suitable concentration gradient difference, which can further promote the gradient precipitation distribution of cobalt at the core-shell interface of the precursor, making it easier for ion-conducting particles to selectively deposit at the primary grain boundaries, thereby constructing a continuous and open lithium-ion transport channel.

[0058] In a preferred embodiment, in step S3, the time interval between the continuous alternating addition of the first ionic solution and the second ionic solution is 5-10 min; and / or, the molar concentration of the complexing agent in the first coprecipitation mixture is 0.5-1.2 mol / L; and / or, step S3 further includes adjusting the flow rate of the first precipitant solution so that the pH value of the first coprecipitation mixture is 6.5-8.5; and / or, the first coprecipitation reaction is carried out under a first stirring, the temperature of the first stirring is 40-80℃, and the rotation speed is 300-800 rpm.

[0059] The 5-10 minute intervals within the aforementioned range facilitate the formation of periodic concentration fluctuations, inducing dynamic supersaturation changes, resulting in a slower nucleation rate and more uniform particle size distribution. In the first coprecipitation mixture, controlling the molar concentration of the complexing agent within the aforementioned range further reduces excessive complexation of metal ions by ammonia molecules, minimizing nucleation delays or excessive grain growth. This allows nickel, manganese, and cobalt ions to more easily precipitate under weak complexation conditions, thus promoting the formation of primary particles with uniform size and distribution. Simultaneously, this concentration range facilitates synergistic effects with low-concentration precipitants, inhibiting particle agglomeration and improving slurry stability. The aforementioned pH value in the first coprecipitation mixture further promotes slow and uniform nucleation of the carbonate phase, reducing the formation of hydroxide impurities due to excessively high pH. The first coprecipitation reaction under these conditions is more conducive to the spheroidization and uniform packing of precursor nuclei.

[0060] To achieve similar effects, the concentration of the third ion solution and the conditions of the second coprecipitation reaction are limited as described above, thereby further improving the controllability of the gradient precipitation of conductive ions, further enhancing the uniform distribution of conductive ions in the outer layer of the core and the crystal growth orientation, and forming a high-density conductive ion enrichment structure. Furthermore, limiting the sum of the molar concentrations of the complexing agent in the first coprecipitation mixture and the metal ions in the nickel-manganese solution to the above range further facilitates the uniform deposition of conductive ions on the surface of the core voids, forming a cobalt-enriched structure.

[0061] In a preferred embodiment, in step S4, the second precipitant solution includes one or more of sodium hydroxide aqueous solution, potassium hydroxide, and calcium hydroxide; and / or, the weight percentage of the second precipitant in the second precipitant solution is 32-40 wt.%; and / or, step S4 further includes adjusting the flow rate of the second precipitant solution so that the pH value of the second coprecipitate mixture is 10.5-12.0; and / or, the time interval between the continuous alternating addition of the third ionic solution and the second ionic solution is 5-10 min; and / or, the mass concentration of the complexing agent in the second coprecipitate mixture is 0.2-0.5 g / L; and / or, the molar concentration of the third ionic solution is 2.2-2.6 mol / L; and / or, the second coprecipitation reaction is carried out under a second stirring, the temperature of the second stirring is 40-80°C, and the rotation speed is 300-800 rpm.

[0062] The aforementioned types of second precipitant solutions can further promote the directional and uniform coating of the hydroxide shell on the surface of the basic carbonate core, significantly improving the integrity of the core-shell structure and the interfacial bonding strength. The concentrations of the second precipitant solutions within the aforementioned range make it easier to control the shell growth rate and crystal orientation, thereby obtaining more regularly arranged primary hydroxide particles. This facilitates the synergistic construction of a composite structure consisting of a highly porous core and a highly channeled shell, significantly enhancing lithium-ion transport efficiency and material cycle stability.

[0063] In a preferred embodiment, in step S5, the molar concentration of the fourth ion solution is 0.8~1.2 mol / L; and / or, the pH value of the third core-shell slurry is 10.5~11.5; and / or, the mass concentration of the complexing agent in the third core-shell slurry is 0.8~1.2 g / L; and / or, the third coprecipitation reaction is carried out under a third stirring, the temperature of the third stirring is 30~90℃, the time is 1~2 h, and the rotation speed is 800~1200 rpm.

[0064] The fourth ion solution within the aforementioned concentration range can further promote the uniform deposition of conductive ions on the surface of primary particles, and further promote the selective enrichment of conductive ions at the grain boundaries and surface defects of primary particles. By limiting the complexing agent or pH value in the third core-shell slurry within the aforementioned range, a more suitable environment is provided for the micro-deposition of conductive ions, which is more conducive to the uniform micro-deposition of conductive ions on the surface of primary particles. The third co-deposition reaction under the above conditions can further promote the diffusion, migration, and crystallization of conductive ions on the particle surface, thereby accelerating the transformation of the precipitate from an amorphous state to a partially crystalline state, making it easier to form regular lithium-ion channels in the shell, and enhancing the migration effect of lithium ions.

[0065] In another typical embodiment of the present invention, a ternary cathode material is also provided, the raw material of which includes the above-mentioned ternary cathode material precursor. Because it is obtained using the precursor of the present invention, the resulting ternary cathode material has a dense secondary spherical morphology, low grain boundary resistance, and stable surface structure, significantly improving the material's rate performance, cycle stability, and low-temperature discharge capability.

[0066] In another typical embodiment of the present invention, a method for preparing the above-mentioned ternary cathode material is also provided, comprising the following steps: mixing the ternary cathode material precursor with lithium hydroxide, and performing a first sintering and a second sintering in sequence to obtain the ternary cathode material, wherein the particle size Dv50 of the lithium hydroxide is 200~800μm.

[0067] The ternary cathode material precursor is mixed with lithium hydroxide and sintered. The carbon dioxide released during the thermal decomposition of the basic carbonate core of the precursor in the first sintering stage, along with the ionic conductivity particles and intergranular defects in the hydroxide shell structure, promotes the optimization of the lithium-ion diffusion path in the solid-state reaction. This effectively alleviates the problem of uneven lithium distribution caused by the low diffusion rate of coarse-particle lithium sources. The second sintering process results in the in-situ formation of a small amount of lithium carbonate on the surface of the successively sintered products, providing active sites for the subsequent construction of the fast-ion conductor layer, thereby improving the interfacial lithium-ion transport capability without additional coating.

[0068] Because the precursor of this invention is used for sintering, even coarse lithium hydroxide particles with a particle size D50 of 200~800μm can still achieve a uniform distribution of lithium ions on its surface, thereby improving the electrochemical performance of the battery while reducing the cost of lithium hydroxide.

[0069] To further improve sintering stability, increase sintering yield, and minimize side reactions, in some embodiments, the molar ratio of the ternary cathode material precursor to lithium hydroxide is (1.01~1.2):1; and / or, the primary sintering temperature is 400~600℃ and the time is 4~8h; and / or, the primary sintering is carried out in a first sintering atmosphere, which includes an oxygen atmosphere and / or an air atmosphere; and / or, the secondary sintering temperature is 800~950℃ and the time is 8~15h; and / or, the secondary sintering is carried out in a second sintering atmosphere, which includes oxygen, air, and carbon dioxide, with a carbon dioxide volume percentage of 0.5~1%.

[0070] In another typical embodiment of the present invention, a positive electrode sheet is also provided, comprising a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, wherein the positive active material layer comprises the aforementioned ternary positive electrode material. Due to the use of the ternary positive electrode material prepared according to the present invention, the highly porous core and channelized shell in its core-shell structure synergistically promote rapid lithium-ion transport, and the fast ion conductor coating layer formed in situ on the surface effectively suppresses interfacial side reactions, significantly improving the rate performance and cycle stability of the electrode sheet.

[0071] In another typical embodiment of the present invention, a lithium-ion battery is also provided, including the above-mentioned positive electrode sheet. Due to the use of the above-mentioned positive electrode sheet, the battery's energy density, rate performance, and long cycle life are significantly improved. Simultaneously, it exhibits stable electrochemical response under low-temperature and high-power conditions, which is beneficial for improving the battery's energy density and process adaptability, making it suitable for applications with stringent safety and cycle stability requirements, such as electric vehicles and energy storage systems.

[0072] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0073] Example 1

[0074] Preparation of ternary cathode material precursors:

[0075] Step S1: Control the reactor temperature at 50℃ and the rotation speed at 500r / min. In a 100L reactor under nitrogen protection, first add deionized water, then add a complexing agent solution (14mol / L ammonia water), and then add the first precipitant solution (sodium carbonate solution, 32wt.%) until the concentration of the complexing agent reaches 3.2g / L and the pH reaches 8.5~9.0, to obtain the precipitate bottom liquid.

[0076] Step S2: Dissolve nickel sulfate, cobalt sulfate, and manganese sulfate in water to prepare a 2.1 mol / L nickel-manganese solution with a molar ratio of nickel:cobalt:manganese of 65:7:28. Control the temperature of the precipitation bottom solution at 50°C and set the rotation speed to 500 r / min. Use a metering pump to pass the nickel-manganese solution (flow rate of 5 L / h), the first ion solution (cobalt sulfate solution, 2.1 mol / L, flow rate of 5 L / h), the first precipitant solution (flow rate of 4.75 L / h), and the complexing agent solution (flow rate of 5 L / h) into the precipitation bottom solution for 1 hour of pre-precipitation to obtain a pre-precipitated slurry.

[0077] Step S3: Keeping the flow rates of the nickel-manganese solution, the first ion solution, the first precipitant solution, and the complexing agent solution constant, under the first stirring conditions of 50°C and 500 rpm, the first ion solution and the second ion solution (cobalt sulfate solution, 2.3 mol / L) are continuously and alternately added to the pre-precipitated slurry with an alternation interval of 5 min to obtain the first precipitate and the first coprecipitate mixture. At the same time, the flow rate of the first precipitant solution is adjusted so that the mass concentration of the complexing agent in the first coprecipitate mixture is reduced to 1.0 g / L and the pH is reduced to 7.0. During this period, the inert gas is switched to a nitrogen-oxygen mixture with an oxygen content of 1.8%. The particle size D50 of the first precipitate is tested online until it reaches 1.5 μm, at which point the reaction is stopped to obtain the core slurry with a solid content of 103 g / L.

[0078] Step S4: Control the reactor temperature at 50℃ and the rotation speed at 800 r / min for the second stirring. Keep the flow rate constant and continue to introduce nickel-manganese solution, second precipitant solution (40 wt.% sodium hydroxide aqueous solution), complexing agent solution, and second ion solution into the core slurry. Simultaneously, continuously and alternately introduce third ion solution (cobalt sulfate solution, 2.5 mol / L) and second ion solution at the same flow rate, with an alternation interval of 5 min, to obtain the second precipitate and the second coprecipitate mixture. At the same time, adjust the flow rate of the second precipitant solution so that the complexing agent concentration in the second coprecipitate mixture reaches 0.35 g / L and the pH reaches 11.5. During this period, the inert gas is switched to a nitrogen-oxygen mixture with an oxygen content of 1.8%. The particle size D50 of the second precipitate is tested online until it reaches 3.4 μm, at which point the reaction is stopped, and the first core-shell slurry with a solid content of 200 g / L is obtained. After filtering the first core-shell slurry, it is transferred to the second ion solution and aged for 1 h to obtain the second core-shell slurry.

[0079] Step S5: The second core-shell slurry is placed in a reactor under a nitrogen atmosphere at 60°C and 1500 r / min for the third stirring. While maintaining a constant flow rate, a complexing agent solution, a fourth ion solution (cobalt sulfate solution, 1 mol / L), and a second precipitate solution are continuously introduced into the second core-shell slurry. The stirring speed is reduced to 1000 r / min, and a third coprecipitation reaction is carried out for 2 hours. Simultaneously, the flow rate of the second precipitate solution is adjusted so that the complexing agent concentration in the second coprecipitate mixture reaches 1.2 g / L, and the pH is 11.8–12, yielding the third core-shell slurry. The third core-shell slurry is then subjected to aging, filtration, washing, and drying to obtain the ternary cathode material precursor.

[0080] Preparation of ternary cathode materials:

[0081] Step S5: According to the molar ratio of lithium hydroxide:(nickel+cobalt+manganese)=1.08:1, lithium hydroxide (particle size D50 is 600μm) and the ternary cathode material precursor are added to a high-speed mixer. Strontium carbonate and zirconium oxide are added in a weight ratio of 1:1. The weight ratio of strontium carbonate to the ternary cathode material precursor is 0.2%:1. The mixture is thoroughly mixed to obtain a pre-sintered mixture. The pre-sintered mixture is loaded into a sagger to form a 5cm high material layer. The material layer is cut into squares with an upper surface of 2cm×2cm using a mold. The spacing between two adjacent blocks is 0.3cm. The blocks are then placed in an atmosphere kiln and sintered at 850℃ in an oxygen atmosphere for 10 hours. After passing through a two-stage roller coarse crusher with an upper layer gap of 7mm and a lower layer gap of 2mm, the mixture is subjected to air jet pulverization to obtain the first sintered product.

[0082] The first sintering product, tungsten oxide, and alumina were added to a high-speed mixer with a weight ratio of 1:0.05%:0.10%. After being mixed evenly, the mixture was placed in a kiln for a second sintering under an oxygen atmosphere at a sintering temperature of 720℃ for 6 hours. After cooling, demagnetization, and sieving, the ternary cathode material was obtained.

[0083] Example 2

[0084] The difference from Example 1 is that,

[0085] In step S1, the molar concentration of ammonia is 10 mol / L, and the molar concentration of sodium carbonate solution is 15 mol / L.

[0086] In step S3, the molar concentration of the first ion solution is 1.8 mol / L and the molar concentration of the second ion solution is 2.0 mol / L. The first ion solution and the second ion solution are continuously and alternately added to the pre-precipitated slurry with an alternation interval of 8 min to obtain the core slurry.

[0087] In step S4, the molar concentration of the third ion solution is 2.2 mol / L, and the weight percentage of the sodium hydroxide solution is 35 wt.%.

[0088] In step S5, the molar concentration of the fourth ion solution is 0.8 mol / L.

[0089] Example 3

[0090] The difference from Example 1 is that,

[0091] In step S1, the molar concentration of ammonia is 20 mol / L, and the molar concentration of sodium carbonate solution is 20 mol / L.

[0092] In step S3, the molar concentration of the first ion solution is 2.2 mol / L and the molar concentration of the second ion solution is 2.4 mol / L. The first ion solution and the second ion solution are continuously and alternately added to the pre-precipitated slurry with an alternation interval of 10 min to obtain the core slurry.

[0093] In step S4, the molar concentration of the third ion solution is 2.5 mol / L, and the weight percentage of the sodium hydroxide solution is 32 wt.%.

[0094] In step S5, the molar concentration of the fourth ion solution is 1.2 mol / L.

[0095] Example 4

[0096] The difference from Example 1 is that,

[0097] In step S1, the concentration of the complexing agent in the precipitate reaches 0.5 g / L;

[0098] In step S3, the molar concentration of ammonia in the first coprecipitation mixture is 0.5 mol / L;

[0099] In step S4, the molar concentration of ammonia in the second coprecipitation mixture is 0.2 mol / L;

[0100] In step S5, the molar concentration of ammonia in the third core-shell slurry is 0.8 mol / L.

[0101] Example 5

[0102] The difference from Example 1 is that,

[0103] In step S1, the concentration of the complexing agent in the precipitate reaches 2 g / L;

[0104] In step S3, the molar concentration of ammonia in the first coprecipitation mixture is 1.2 mol / L;

[0105] In step S4, the molar concentration of ammonia in the second coprecipitation mixture is 0.5 mol / L;

[0106] In step S5, the molar concentration of ammonia in the third core-shell slurry is 1.2 mol / L.

[0107] Example 6

[0108] The difference from Example 1 is that,

[0109] In step S1, the pH value of the precipitation solution is 8.5;

[0110] In step S3, the pH value of the first coprecipitate mixture is 6.5;

[0111] In step S4, the pH value of the second coprecipitate mixture is 10.5;

[0112] In step S5, the pH value of the third core-shell slurry is 10.5.

[0113] Example 7

[0114] The difference from Example 1 is that,

[0115] In step S1, the pH value of the precipitation solution reaches 10.5;

[0116] In step S3, the pH value of the first coprecipitate mixture is 8.5;

[0117] In step S4, the pH value of the second coprecipitate mixture is 12.0;

[0118] In step S5, the pH value of the third core-shell slurry is 11.5.

[0119] Example 8

[0120] The difference from Example 1 is that,

[0121] The first ion solution, the second ion solution, the third ion solution, and the fourth ion solution all use tungsten nitrate solution;

[0122] In step S1, the first precipitant solution is an aqueous solution of ammonium carbonate;

[0123] In step S3, the D50 of the first precipitate is 1.5;

[0124] In step S4, the second precipitant solution is an aqueous solution of calcium hydroxide; the D50 of the second precipitate is 2.5.

[0125] Example 9

[0126] The difference from Example 1 is that,

[0127] The first ion solution, the second ion solution, the third ion solution, and the fourth ion solution all use calcium nitrate solution;

[0128] In step S1, the first precipitant solution is an aqueous solution of potassium carbonate;

[0129] In step S3, the D50 of the first precipitate is 2.2;

[0130] In step S4, the second precipitant solution is an aqueous solution of potassium hydroxide; the D50 of the second precipitate is 6.0.

[0131] Example 10

[0132] The difference from Example 1 is that,

[0133] In step S2, the protective atmosphere is argon; a nickel-manganese solution with a concentration of 1.8 mol / L is prepared according to a molar ratio of nickel:cobalt:manganese of 60:10:30; the flow rate of the nickel-manganese solution is 2.5 h / L, the flow rate of the first precipitant solution is 2.25 L / h, and the preprecipitation time is 2 h;

[0134] In step S3, the temperature of the first stirring is 40℃ and the speed is 800 rpm;

[0135] In step S4, the temperature of the second stirring is 40℃ and the rotation speed is 800 rpm;

[0136] In step S5, the temperature of the third stirring is 30℃ and the speed is 1200rpm.

[0137] Example 11

[0138] The difference from Example 1 is that,

[0139] In step S2, a nickel-manganese solution with a concentration of 2.2 mol / L is prepared according to a molar ratio of nickel:cobalt:manganese of 80:10:10; the flow rate of the nickel-manganese solution is 10 h / L, the flow rate of the first precipitant solution is 10 L / h, and the pre-precipitation time is 0.5 h.

[0140] In step S3, the temperature of the first stirring is 80℃ and the speed is 300 rpm;

[0141] In step S4, the temperature of the second stirring is 80℃ and the rotation speed is 300 rpm;

[0142] In step S5, the temperature of the third stirring is 90℃ and the speed is 800 rpm.

[0143] Comparative Example 1

[0144] Preparation of ternary cathode material precursors:

[0145] Step S1: Nickel sulfate, cobalt sulfate, and manganese sulfate are prepared into a nickel-cobalt-manganese solution at a molar ratio of 2.1 mol / L and 50:20:30. The solution is placed in a 100L reactor and kept at 60°C. The rotation speed is controlled at 1500 r / min. Deionized water, sodium hydroxide solution (40 wt.%), and ammonia water (14 mol / L) are continuously added to the nickel-cobalt-manganese solution to make the pH value of the nickel-cobalt-manganese solution 12.5~12.8 and the concentration of complexing agent in the nickel-cobalt-manganese solution reach 1.2 g / L, thus obtaining the first precipitation solution.

[0146] In step S2, under a nitrogen atmosphere, a first metal salt solution (nickel-cobalt-manganese solution, 2.1 mol / L), sodium hydroxide solution (40 wt.%), and ammonia (14 mol / L) are continuously added to the first precipitation solution. The pH of the first precipitation solution is gradually reduced to 12.0 over 4 hours, ensuring the concentration of the complexing agent in the first precipitation solution is controlled between 1.8 and 2.0 g / L. Online testing shows that the solid particle size D50 in the first precipitation solution increases to 2.0 μm. The rotation speed is then reduced to 1000 r / min until the solid particle size D50 increases to 3.4 μm, at which point the reaction is stopped, yielding a second precipitation solution. The second precipitation solution is then subjected to aging, filtration, washing, and drying to obtain the nickel-cobalt-manganese hydroxide precursor.

[0147] Preparation of ternary cathode materials:

[0148] Step S3: Lithium carbonate and nickel cobalt manganese hydroxide precursor are added to a high-speed mixer according to a molar ratio of lithium carbonate: nickel cobalt manganese hydroxide precursor = 1.01:1. Strontium carbonate and zirconium oxide are added in a weight ratio of 1:1. The weight ratio of strontium carbonate to ternary cathode material precursor is 0.2%:1. The mixture is thoroughly mixed to obtain a pre-sintered mixture. The pre-sintered mixture is loaded into a sagger to form a 5cm high material layer. The material layer is cut into squares with an upper surface area of ​​2cm × 2cm using a mold. The spacing between two adjacent blocks is 0.3cm. The blocks are then placed in an atmosphere furnace and sintered at 850℃ in an oxygen atmosphere for 10 hours to obtain a sintered product. The sintered product is then subjected to a two-stage coarse crusher with an upper layer gap of 7mm and a lower layer gap of 2mm, followed by air jet milling to control the particle size D50 to 3.0~4.0μm, thus obtaining the ternary cathode material.

[0149] Comparative Example 2

[0150] The difference from Comparative Example 1 is that,

[0151] In step S1, deionized water, sodium carbonate solution and ammonia water are continuously added to the nickel-cobalt-manganese solution to obtain the first precipitate solution;

[0152] In step S2, a first metal salt solution, sodium carbonate solution, and ammonia are continuously added to the first precipitation solution to obtain a second precipitation solution; the second precipitation solution is then aged, filtered, washed, and dried to obtain a nickel-cobalt-manganese carbonate precursor.

[0153] Comparative Example 3

[0154] Commercially available NCM622 cathode material.

[0155] Performance testing:

[0156] The ternary cathode material precursors and ternary cathode materials prepared in the above embodiments and comparative examples were analyzed and tested as follows, and the results are shown in Tables 1, 2, 3 and 4.

[0157] 1. Core porosity: According to GB / T 21650.1-2008 "Determination of pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption method - Part 1: Mercury porosimetry", a fully automated mercury porosimeter (AutoPore IV 9500, Micromeritics, USA) with a pressure range of 0.5~400MPa was used to measure the specific surface area and pore size distribution. The core corresponds to a pore size range of 0.01-0.1μm. The cumulative mercury ingress within this range was recorded, and the porosity was calculated. Each sample was tested 3 times, and the arithmetic mean was taken.

[0158] 2. Particle size Dv50: Online testing is conducted using an online particle size analyzer (Insitec, Malvern, UK) to test the solid phase of the slurry in the reactor. The reaction slurry is collected in real time, automatically dispersed, and then tested. The particle size value corresponding to the cumulative distribution reaching 50% is recorded in terms of volume distribution. The test is performed every 5 minutes.

[0159] Offline testing was conducted according to the method of GB / T 19077-2016 "Particle size analysis by laser diffraction", using a laser particle size analyzer (Mastersizer 3000, Malvern, UK) to perform offline testing on the solid phase of the slurry.

[0160] 3. BET specific surface area: The specific surface area was tested using a specific surface area meter (ASAP 2460, Micromeritics, USA) in accordance with the method of GB / T 19587-2017 "Determination of specific surface area of ​​solid substances by gas adsorption BET method".

[0161] 4. Dimensions in length and width: Measured using a scanning electron microscope.

[0162] 5. Thickness dimension of nickel-cobalt-manganese hydroxide sheet: Cross-sectional measurement was performed using focused ion beam scanning electron microscopy (FIB-SEM). Precursor particles were embedded in epoxy resin, cured, and then cross-sectionally cut using FIB (Focused Ion Beam Helios G4 UC, FEI, USA). Backscattered electron images of the particle cross-section were captured under SEM (magnification 10,000-50,000x). The radial distance from the outer surface of the particle to the core boundary was measured. Twenty particles were randomly selected, and measurements were taken in four different directions for each particle; the arithmetic mean was calculated.

[0163] The thickness-direction dimensions of primary nickel-cobalt-manganese hydroxide particles were measured using a cross-sectional method with a transmission electron microscope (Talos F200X, FEI, USA). Specific steps included: preparing a thin cross-section (100 nm thick) of the precursor particles using a fibrillation-in-the-brush (FIB) method; observing the cross-section under high-resolution SEM (50,000-100,000x magnification) or TEM; and randomly measuring 50 primary particles and taking the arithmetic mean.

[0164] Thickness of nickel-cobalt-manganese hydroxide sheets: Measured using a scanning electron microscope (Sigma 300, Zeiss, Germany) according to GB / T 33834-2017 "Microbeam Analysis Scanning Electron Microscopy Image Analysis Method". The precursor sample was dispersed on conductive adhesive and sputtered with gold. The sheet-like morphology of the precursor shell surface was observed under SEM (magnification 50,000-100,000). The dimensions of the sheet-like structure perpendicular to the sheet surface were measured. Fifty sheet-like structures were randomly measured, and the arithmetic mean was taken.

[0165] 6. Volume Percentage: The core volume percentage was determined using focused ion beam scanning electron microscopy (FIB-SEM) combined with image analysis. Precursor particles were embedded in epoxy resin, cured, and then cross-sectionally cut using FIB. Backscattered electron images of the particle cross-section were captured using SEM (magnification 5000–20000x). Image analysis software was used to calculate the percentage of the core region area to the total particle area. Twenty particles were randomly selected for measurement, and the arithmetic mean was taken.

[0166] The percentage of void volume in the outer shell = 100% - the percentage of core volume - the percentage of primary particle volume in the outer shell. The percentage of primary particle volume in the outer shell is obtained by analyzing the FIB-SEM cross-sectional image and calculating the percentage of area occupied by primary particles.

[0167] 7. Tap density: The tap density was tested according to the method of GB / T 5162-2021 "Determination of tap density of metal powders" using a tap density tester (PT-TD200, Pintek, China).

[0168] 8. Rockwell hardness: Tested using a hardness tester (574R, Wilson, USA).

[0169] 9. Electrochemical performance:

[0170] A constant current charge-discharge method was used, and a coin cell testing system was employed for testing. The positive electrode material, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 90:5:5. N-methylpyrrolidone (NMP) was added and ground into a uniform slurry, which was then coated onto aluminum foil and vacuum dried at 120°C for 12 hours. The slurry was then cut into 12mm diameter discs to obtain the positive electrode sheet. A 15.6mm diameter, 0.6mm thick lithium metal sheet was used as the negative electrode. A 19mm diameter Celgard 2400 polypropylene separator was used. 1M LiPF6 was dissolved in EC / DMC / EMC (volume ratio 1:1:1), and 2wt.% VC was added to obtain the electrolyte. The above battery components were assembled into CR2032 coin cells in an argon-filled glove box (H2O < 0.1ppm, O2 < 0.1ppm). Testing was conducted using a coin cell testing system (CT-4008T, Neware, China).

[0171] Rate performance: The test temperature was 25±2℃, and the voltage range was 2.8-4.3V. The material was charged at constant current rates of 0.1C, 0.5C, 1C, and 2C to 4.3V, and then charged at constant voltage until the current dropped to 0.05C. It was then discharged at constant current rates of 0.1C, 0.5C, 1C, and 2C to 2.8V, where the 1C current density was set according to the material's theoretical capacity. Each rate was repeated three times, and the arithmetic mean was taken. 1C / 0.1C retention rate = 1C discharge capacity ÷ 0.1C discharge capacity × 100%.

[0172] Cycle life: The test temperature was 25±2℃, and the voltage range was 2.8~4.3V. First, the battery was charged at a constant current of 0.1C to 4.3V, then charged at a constant voltage until the current dropped to 0.05C, followed by a constant current discharge of 0.1C to 2.8V. This process was repeated three times for activation. Then, the battery was charged at a constant current of 1C to 4.3V, then charged at a constant voltage until the current dropped to 0.05C, and finally discharged at a constant current of 1C to 2.8V, for a total of 500 cycles. The 1C current density was set according to the theoretical capacity of the material. The discharge capacity of each cycle was recorded, and the capacity retention rate was calculated as: discharge capacity in week n ÷ discharge capacity in week 1 × 100%. The capacity retention rate at week 500 was also recorded. Three batteries of each sample were tested repeatedly, and the arithmetic mean was taken.

[0173] Low-temperature power: The test temperature was 25±2℃, and the voltage range was 2.8~4.3V. The battery was first charged at a constant current of 0.2C to 4.3V, then charged at a constant voltage until the current dropped to 0.05C, followed by a constant current discharge at 0.2C to 2.8V. This process was repeated three times for activation. Afterward, the battery was charged at a constant current of 0.2C to 4.3V, then charged at a constant voltage until the current dropped to 0.05C. It was then placed in a -20±2℃ low-temperature chamber (MC-710, ESPEC Japan) and left to stand for 4 hours. It was then discharged at -20℃ at a constant current of 0.2C to 2.8V, and the low-temperature discharge capacity was recorded. Simultaneously, it was discharged at 25±2℃ at a constant current of 0.2C to 2.8V, and the room temperature discharge capacity was recorded as a baseline. The low-temperature power retention rate was calculated as: Low-temperature discharge capacity ÷ Room temperature discharge capacity × 100%. Three batteries were tested for each sample, and the arithmetic mean was taken.

[0174] Table 1

[0175]

[0176] Table 2

[0177]

[0178] Table 3

[0179]

[0180] Table 4

[0181]

[0182] A cross-sectional view of the ternary cathode material precursor obtained in Example 1 is shown below. Figure 1 As can be seen, the precursor exhibits a clear core-shell structure, with a distinct interface between the core and shell. The shell is composed of tightly stacked nickel-cobalt-manganese hydroxide primary particles, with uniform thickness, completely covering the core surface. Uniformly distributed ionic conductivity particles are visible on the shell surface and at the grain boundaries of the primary particles. See the cross-sectional view of the precursor core in Example 1. Figure 2 As can be seen, the core exhibits a loose, porous structure with uniformly distributed pores. This porous structure is naturally formed during the co-precipitation process of carbonates, providing abundant channels for the inward diffusion of lithium ions during subsequent sintering. The morphology of the ternary cathode material precursor obtained in Example 1 is shown in the figure. Figure 3 As can be seen, the precursor consists of spherical or near-spherical secondary particles. The particle surface is composed of stacked, plate-like primary particles of nickel-cobalt-manganese hydroxide. The plate-like structures are arranged in an interlaced manner, forming abundant surface pores, which is beneficial for the wetting and penetration of the lithium salt melt. The morphology of the first sintered product obtained in Example 1 is shown in the figure. Figure 4As can be seen, after pre-sintering and high-temperature sintering, the particles still maintain a complete spherical morphology, with a smooth and dense surface, and no obvious cracks or breakage. The lithium element is evenly distributed inside the particles, proving that the precursor structure of this invention effectively promotes the uniform diffusion of lithium ions.

[0183] The morphology of the ternary cathode material precursor obtained in Comparative Example 1 is shown in the figure. Figure 5 As can be seen, the precursor exhibits a spherical morphology, with its surface composed of densely packed primary hydroxide particles, exhibiting few surface pores and no ionic conductivity particle loading. The morphology of the sintered product obtained in Comparative Example 1 is shown in the figure. Figure 6 It can be seen that after sintering, some sintering necks and local melting phenomena appear on the surface of the particles, but the morphology is still close to that of the initial precursor, indicating that lithium ions have not been fully diffused into the entire particle.

[0184] As can be seen, Comparative Example 1, due to the use of a pure hydroxide precursor, lacks porous channels generated by carbonate decomposition within the particles, and without ionicly conductive particles to guide lithium-ion diffusion, lithium ions can only slowly diffuse from the particle surface inwards relying on concentration gradients. This results in insufficient lithiation in the central region of large particles, affecting the material's capacity utilization and cycle stability. While Comparative Example 2, although generating porous channels through carbonate core decomposition which facilitates lithium-ion diffusion, suffers from insufficient mechanical strength due to the overall carbonate structure of the precursor, making it prone to particle breakage and collapse during sintering. Furthermore, the lack of a hydroxide shell for protection and ionicly conductive particles for guidance leads to poor structural integrity and cycle stability in the cathode material. Although Comparative Example 3 employs a mature commercial production process, it is still limited by the conventional precursor structure, resulting in insufficient lithiation uniformity. Its rate performance and low-temperature performance are inferior to those of the embodiments of this invention.

[0185] As can be seen from the above, compared with the comparative example, the ternary cathode material precursor of the present invention adopts a core-shell structure with spherical secondary particles. Its core is composed of nickel-cobalt-manganese carbonate, and its outer shell is assembled from nickel-cobalt-manganese hydroxide primary particles, with ionic conductivity particles loaded on the surface of the hydroxide primary particles. When this structure undergoes a high-temperature solid-state reaction with coarse-grained lithium hydroxide, the carbonate in the core decomposes upon heating to generate carbon dioxide gas, locally promoting the formation of the lithiation reaction environment. Simultaneously, the ionic conductivity particles on the outer shell significantly enhance the migration rate of lithium ions at the solid-state interface, thereby effectively overcoming the problem of uneven lithiation caused by the large particle size and long diffusion path of coarse-grained lithium hydroxide, achieving a uniform distribution of lithium in the precursor particles. Furthermore, the above preparation method does not rely on fine-particle lithium sources, effectively improving the structural consistency and electrochemical performance of the cathode material while simplifying the raw material preparation process.

[0186] Furthermore, it can be seen that the overall effect is better when all process parameters are within the preferred range of the present invention.

[0187] 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 ternary cathode material precursor, characterized in that, The ternary cathode material precursor is a core-shell structured spherical secondary particle, wherein the core-shell structure includes a precursor core and a precursor shell; wherein... The precursor core comprises nickel cobalt manganese carbonate; The precursor shell comprises nickel-cobalt-manganese hydroxide primary particles; The nickel-cobalt-manganese hydroxide primary particles are surface-loaded with ion-conducting particles, which contain metallic elements.

2. The ternary cathode material precursor according to claim 1, characterized in that, The chemical formula of the ternary cathode material precursor is Ni x Co y Mn z (OH)2M@Ni x Co y Mn z CO3, where 0.6 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, M is one or more of Ni, Co, Mn, W, Al, Mg, Ca; and / or, The porosity of the precursor core is 1.84~9.31%; and / or, The porosity of the precursor shell is 10-50%; and / or, In the ternary cathode material precursor, the volume percentage of the precursor core is 10-30%; and / or, The particle size Dv50 of the ternary cathode material precursor is 2.0~6.0 μm; and / or, The BET specific surface area of ​​the ternary cathode material precursor is 5~30m². 2 / g; and / or, The tap density of the ternary cathode material precursor is 1.3~2.1 g / cm³. 3 ; and / or, The primary nickel-cobalt-manganese hydroxide particles are formed by stacking nickel-cobalt-manganese hydroxide sheets. These sheets have a length direction, a width direction, and a thickness direction. The sheets are stacked along a plane perpendicular to the length direction to form the primary nickel-cobalt-manganese hydroxide particles. The nickel-cobalt-manganese hydroxide sheet has a length dimension of 160-200 nm, a width dimension of 85-108 nm, and a thickness dimension of 40-50 nm; and / or, The primary particles of the nickel-cobalt-manganese hydroxide have a length dimension of 160-200 nm, a width dimension of 350-420 nm, and a thickness dimension of 350-420 nm.

3. The ternary cathode material precursor according to claim 2, characterized in that, The chemical formula of the precursor inner core is Ni x Co y Mn z CO3, where 0.6 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3; and / or, The chemical formula of the precursor shell is Ni x Co y Mn z (OH)2M, where 0.6 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, and M is the metal element of the ionic conductive particles; and / or, The ratio of the size of the nickel cobalt manganese hydroxide primary particles to the size of the nickel cobalt manganese hydroxide sheet along the thickness direction is (8~10):

1.

4. The method for preparing the ternary cathode material precursor according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step S1: Mix the first precipitant solution, the complexing agent solution, and deionized water to obtain the precipitate bottom solution; Step S2: Under a protective atmosphere, the nickel-manganese solution, the first ion solution, and the complexing agent solution are introduced into the precipitation bottom liquid at the same flow rate, while the first precipitant solution is introduced into the precipitation bottom liquid to perform pre-precipitation and obtain a pre-precipitated slurry. Step S3: Keeping the flow rates of the nickel-manganese solution, the first ion solution, the first precipitant solution, and the complexing agent solution constant, the first ion solution and the second ion solution are continuously and alternately introduced into the pre-precipitated slurry at the same flow rate as the nickel-manganese solution to carry out the first coprecipitation reaction, so as to obtain the first precipitate and the first coprecipitate mixture. The reaction is stopped when the particle size D50 of the first precipitate is 1.5~2.2μm, and the core slurry is obtained. Step S4: Maintaining a constant flow rate, continue to introduce the nickel-manganese solution, the second precipitant solution, the complexing agent solution, and the second ion solution into the core slurry. Simultaneously, alternately introduce the third ion solution and the second ion solution at the same flow rate as the nickel-manganese solution to carry out a second coprecipitation reaction, thereby obtaining a second precipitate and a second coprecipitate mixture. Stop the reaction when the particle size D50 of the second precipitate is 2.5~6.0μm to obtain the first core-shell slurry. Filter the first core-shell slurry to obtain the second precipitate, and add the second ion solution to age it to obtain the second core-shell slurry. Step S5: Keeping the flow rate constant, continue to introduce the complexing agent into the second core-shell slurry, and simultaneously introduce the fourth ion solution at the same flow rate as the complexing agent to carry out the third coprecipitation reaction, thereby obtaining the third core-shell slurry; wash and dry the third core-shell slurry in sequence to obtain the ternary cathode material precursor; The molar concentration of the first ion solution is less than the molar concentration of the second ion solution; the molar concentration of the second ion solution is less than the molar concentration of the third ion solution; and the molar concentration of the fourth ion solution is less than the molar concentration of the first ion solution.

5. The method for preparing the ternary cathode material precursor according to claim 4, characterized in that, The complexing agent solution comprises one or more of ammonia, citric acid, tartrate, and EDTA; and / or, the molar concentration of the complexing agent in the complexing agent solution is 10-20 mol / L; and / or, Independently, the first ionic solution, the second ionic solution, the third ionic solution, and the fourth ionic solution each contain a metal salt, wherein the metal element of the metal salt includes one or more of cobalt, nickel, manganese, tungsten, aluminum, magnesium, and calcium, and the metal salt is added in the form of one or more of sulfate, carbonate, and nitrate; and / or, In step S1 The first precipitant solution comprises one or more of sodium carbonate aqueous solution, potassium carbonate aqueous solution, and ammonium carbonate aqueous solution; and / or, the weight percentage of the first precipitant in the first precipitant solution is 32~40 wt.%; and / or, The pH of the precipitation solution is 8.5~10.5; and / or, the weight concentration of the complexing agent in the precipitation solution is 0.5~2.5 g / L; and / or, In step S2 The pre-precipitation time is 0.5~2h; and / or, The flow rate ratio of the first precipitant solution to the nickel-manganese solution is (0.9~1.0):1; and / or, The protective atmosphere includes nitrogen and / or argon; and / or, In the nickel-manganese solution, the sum of the molar concentrations of the metal ions is 1.8~2.2 mol / L; and / or, in the nickel-manganese solution, the molar ratio of nickel ions to manganese ions is (60~80):(10~30); and / or, the nickel-manganese solution further includes cobalt ions, and the molar ratio of nickel ions, cobalt ions, and manganese ions is (60~80):(7~10):(10~30); and / or, The molar concentration of the first ion solution is 1.8~2.2 mol / L; and / or, In step S3 The molar concentration of the second ion solution is 2.0~2.4 mol / L; and / or, The time interval between the continuous alternating addition of the first ionic solution and the second ionic solution is 5-10 min; and / or, In the first coprecipitation mixture, the molar concentration of the complexing agent is 0.5~1.2 mol / L; and / or, Step S3 further includes adjusting the flow rate of the first precipitant solution to achieve a pH value of 6.5-8.5 for the first co-precipitate mixture; and / or, And / or, the first coprecipitation reaction is carried out under a first stirring, the temperature of the first stirring being 40~80℃ and the rotation speed being 300~800rpm.

6. The method for preparing the ternary cathode material precursor according to claim 4, characterized in that, In step S4 The second precipitant solution comprises one or more of sodium hydroxide aqueous solution, potassium hydroxide, and calcium hydroxide; and / or, the weight percentage of the second precipitant in the second precipitant solution is 32-40 wt.%; and / or, Step S4 further includes adjusting the flow rate of the second precipitant solution so that the pH value of the second coprecipitate mixture is 10.5~12.0; and / or, The time interval between the continuous alternating addition of the third ion solution and the second ion solution is 5-10 minutes; and / or, In the second coprecipitation mixture, the mass concentration of the complexing agent is 0.2~0.5 g / L; and / or, The molar concentration of the third ion solution is 2.2~2.6 mol / L; and / or, The second coprecipitation reaction is carried out under a second stirring, the temperature of which is 40~80℃ and the stirring speed is 300~800rpm; and / or, In step S5 The molar concentration of the fourth ion solution is 0.8~1.2 mol / L; and / or, The pH value of the third core-shell slurry is 10.5~11.5; and / or, the mass concentration of the complexing agent in the third core-shell slurry is 0.8~1.2 g / L; and / or, The third coprecipitation reaction is carried out under a third stirring, the temperature of which is 30~90℃, the time is 1~2h, and the speed is 800~1200rpm.

7. A ternary cathode material, characterized in that, The raw materials for the ternary cathode material include the ternary cathode material precursor as described in any one of claims 1 to 3.

8. The method for preparing the ternary cathode material according to claim 7, characterized in that, Includes the following steps: The ternary cathode material precursor is mixed with lithium hydroxide and subjected to a first sintering and a second sintering to obtain the ternary cathode material, wherein the particle size Dv50 of the lithium hydroxide is 200~800μm.

9. A positive electrode sheet, comprising a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, characterized in that, The positive electrode active material layer includes the ternary positive electrode material as described in claim 7 or 8.

10. A lithium-ion battery, characterized in that, Includes the positive electrode sheet as described in claim 9.

Images