Ternary positive electrode material precursor and preparation method thereof, positive electrode material, and secondary battery

Abstract

The present application relates to the technical field of lithium-ion batteries, and provides a method for preparing a ternary positive electrode material precursor. In a protective atmosphere, a metal mixed salt solution, a complexing agent solution, a precipitant solution, and an interface inducing agent solution are respectively added to a first reaction container containing a base liquid by continuous feeding to react. When the precipitate reaches a predetermined particle size, the feeding of the interface inducing agent solution is stopped, and the obtained slurry is returned to the first reaction container for continuous reaction after dense concentration treatment. When the precipitate reaches a predetermined particle size, the dense concentration treatment is stopped, and the obtained slurry overflows into a second reaction container, and the slurry overflowing in the second reaction container is returned to the first reaction container for continuous reaction after dense concentration treatment. When the precipitate reaches a predetermined particle size, a qualified slurry is obtained. The method provided by the present application makes the growth rate of the precursor approximately uniform, and the precursor particles with high tap density, good sphericity, and regular primary particle size are prepared.

Description

Technical Field

[0001] The present application belongs to the technical field of lithium-ion batteries, and in particular relates to a ternary positive electrode material precursor and a preparation method thereof, as well as a positive electrode material and a secondary battery. Background Art

[0002] Ternary lithium-ion batteries have many advantages such as high energy density, high power density, good cycle performance, no memory effect, and green environmental protection. They are widely used in 3C products, electric vehicles, small energy storage products and other fields. With the continuous expansion of the scope of application, lithium-ion batteries must adapt to various environmental conditions in addition to cost, safety and energy density to broaden their wide application. However, the ambient temperature has a great influence on the performance of most rechargeable lithium batteries. The tolerance of the ternary positive electrode material, which is the core of the ternary lithium battery, in low or high temperature environments cannot meet the application requirements under extreme conditions. When the operating temperature is too low, the ion transmission is slow, the SCI membrane impedance increases, resulting in severe battery polarization and large internal resistance, and the battery output voltage and capacity drop sharply, causing the energy and power density to decay rapidly. However, when the temperature is too high, the positive electrode material is prone to various interfacial reactions with the electrolyte, the ion diffusion rate is also increased, and it is easy to cause thermal runaway. High temperature may also cause the dissolution and diffusion of nickel-cobalt-manganese oxides, so that the active material shuttled to the negative electrode side reacts with lithium metal, resulting in active material loss and capacity decay, which in turn causes safety problems. Therefore, when the temperature is below 0℃ or above 40℃, the energy density and power density of lithium batteries are very poor at low temperatures and drop rapidly at high temperatures, which makes the battery unable to meet the application requirements when operating at lower and higher temperatures, severely limiting the application of lithium batteries in high-cold / high-temperature areas.

[0003] In the prior art, for low-temperature lithium-ion batteries, positive and negative electrode materials with high ion conduction rate and conductivity, and electrolyte solvents with high conductivity and low crystallization temperature are usually used at low temperatures; while for lithium-ion batteries used at high temperatures, the surface of positive and negative electrode materials needs to be passivated from the design point of view to avoid more side reactions that lead to increased battery impedance and decreased cycle performance. Functional additives are usually added to the electrolyte to improve battery performance. However, there are few public reports on lithium-ion battery manufacturing technology for use in the full temperature range. The performance and life of low-temperature lithium-ion batteries in the current public documents will be reduced when used at high temperatures, while high-temperature lithium-ion batteries will experience lithium precipitation when used at low temperatures, and the safety performance of the battery will be greatly reduced.

[0004] Therefore, it is very necessary and challenging to develop a high-capacity, wide-temperature-range nickel-cobalt-manganese ternary cathode material precursor, which is of great significance to accelerate its industrialization process and meet the full-temperature-range usage requirements of lithium-ion battery energy storage materials. Summary of the invention

[0005] The purpose of the present application is to provide a ternary positive electrode material precursor and a preparation method thereof, aiming to solve the problem that the tolerance of the ternary positive electrode material in low or high temperature environments cannot meet the application requirements.

[0006] Another object of the present application is to provide a positive electrode material and a secondary battery containing the positive electrode material, so as to solve the technical problem that the existing secondary batteries are difficult to meet the use requirements in cold and high temperature areas.

[0007] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0008] In a first aspect, the present application provides a method for preparing a ternary cathode material precursor, comprising the following steps:

[0009] S1. preparing a metal mixed salt solution, a complexing agent solution, a precipitant solution and an interface inducing agent solution respectively, wherein the metal mixed salt solution contains nickel, cobalt and manganese;

[0010] S2. In a protective atmosphere, the metal mixed salt solution, the complexing agent solution, the precipitant solution and the interface inducing agent solution are added to the first reaction container containing the base solution by continuous feeding to carry out a co-precipitation reaction. When the precipitate reaches a first predetermined particle size, the feeding of the interface inducing agent solution is stopped to obtain an initial slurry;

[0011] S3, returning the initial slurry after the first dense concentration treatment to the first reaction container to be mixed with the metal mixed salt solution, the complexing agent solution and the precipitant solution added to the first reaction container to continue the co-precipitation reaction, and stopping the first dense concentration treatment when the precipitate reaches a second predetermined particle size to obtain an intermediate slurry;

[0012] S4, overflowing the intermediate slurry into the second reaction container, and returning the intermediate slurry overflowing in the second reaction container to the first reaction container after the second dense concentration treatment to be mixed with the metal mixed salt solution, complexing agent solution and precipitant solution added into the first reaction container to continue the precipitation reaction, and the solid content of the slurry formed after the second dense concentration treatment being returned is the same as the solid content of the slurry in the first reaction container being received, and when the precipitate reaches a third predetermined particle size, stop conveying the slurry formed after the second dense concentration treatment to the first reaction container, and stop adding the metal mixed salt solution, complexing agent solution and precipitant solution, so as to obtain a qualified slurry;

[0013] S5. Filter and wash the qualified slurry to obtain a ternary positive electrode material precursor.

[0014] In a second aspect, the present application provides a ternary positive electrode material precursor, which is prepared using the preparation method of the ternary positive electrode material precursor provided in the first aspect.

[0015] In a third aspect, the present application provides a positive electrode material, which is prepared by mixing the ternary positive electrode material precursor of the present application with a lithium salt.

[0016] In a fourth aspect, the present application provides a secondary battery, and the secondary battery includes the positive electrode material of the present application.

[0017] The first aspect of the present application provides a method for preparing a ternary positive electrode material precursor. First, a seed crystal of the precursor is prepared by a coprecipitation reaction. When the precipitate reaches a first predetermined particle size, a first dense concentration treatment is performed, so that the solid content in the precursor slurry in the first reaction container gradually increases, so that the coprecipitation reaction enters a seed crystal stabilization period; after the precipitate reaches a second predetermined particle size, the first dense concentration treatment is stopped, the slurry in the first reaction container overflows into the second reaction container, and the precursor material in the second reaction container is concentrated by a thickener, and the concentrated slurry in the thickener is transported back to the reaction container. The first reaction container is provided, and the solid content of the slurry formed after the second dense concentration treatment being returned is controlled to be the same as the solid content of the slurry in the first reaction container being received, so as to ensure that the precursor slurry in the first reaction container has a stable solid content. Under the condition of a certain solid content, the growth rate of the precursor in the first reaction container can be approximately uniform, so that the crystal structure of the precursor can be regulated, and the purpose of controlling the arrangement and stacking of the primary particles of the ternary positive electrode material precursor can be achieved, thereby preparing precursor particles with high tap density, good sphericity and regular primary particle size.

[0018] The ternary cathode material precursor provided in the second aspect of the present application is prepared by the preparation method of the present application. The precursor is a micron-sized secondary spherical particle formed by assembling primary particles. The primary particles on the surface of the secondary particles are arranged regularly and in rows. In particular, the primary particles are alternately arranged in an orderly manner and have certain gaps. When this ternary cathode material precursor is used to make the cathode material of a lithium-ion battery, it can significantly improve the initial charge and discharge performance, cycle performance and effective operating temperature range of the lithium-ion battery.

[0019] The cathode material provided in the third aspect of the present application is prepared by mixing the ternary cathode material precursor of the present application with lithium salt. The primary particles on the surface of the secondary spherical particles of the ternary cathode material precursor product of the present application are arranged regularly and in a row. In particular, the primary particles are alternately ordered and have certain gaps, which is beneficial to the ternary cathode material precursor in the mixed lithium roasting process, promoting the transmission of lithium ions, and accelerating the mass transfer of lithium ions inside the particles during charging and discharging. More ions reach the particle surface per unit time, allowing lithium ions to be quickly embedded and removed, thereby having high electronic conductivity and ionic conductivity, thereby improving the capacity of the cathode material. In addition, the lattice dimension anisotropy of the orderly grown nano-scale needle-shaped primary particles will be improved, and the dense and orderly structure forms a stable interface during the charging and discharging process, which can effectively offset the anisotropic contraction and expansion of the primary particles caused by temperature changes or voltage changes. The increase in internal stress caused by the expansion and contraction, avoid the erosion of the electrolyte on the inside of the particles; on the other hand, smaller grains have a larger grain boundary contact area, and the internal stress can be more evenly dispersed, thereby inhibiting the rapid formation of cracks, greatly improving the stability of the cathode material.

[0020] The secondary battery provided in the fourth aspect of the present application, because it includes a positive electrode material prepared using the ternary positive electrode material precursor of the present application, enables the lithium-ion battery to have excellent initial charge and discharge performance, cycle performance, and effective operating temperature range, and can meet the use requirements of high-cold and high-temperature areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 is a SEM image of the ternary cathode material precursor provided in Example 1 of the present application;

[0023] Figure 2 is a SEM image of the ternary cathode material precursor provided in Example 2 of the present application;

[0024] Figure 3 This is a SEM image of the ternary cathode material precursor provided in Comparative Example 1 of the present application;

[0025] Figure 4 This is a particle size distribution diagram of the ternary positive electrode material precursor provided in Example 1 of the present application. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0027] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0028] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0029] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0030] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0031] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0032] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0033] A first aspect of an embodiment of the present application provides a method for preparing a ternary cathode material precursor, comprising the following steps:

[0034] S1. preparing a metal mixed salt solution, a complexing agent solution, a precipitant solution and an interface inducing agent solution respectively, wherein the metal mixed salt solution contains nickel, cobalt and manganese;

[0035] S2. In a protective atmosphere, the metal mixed salt solution, the complexing agent solution, the precipitant solution and the interface inducing agent solution are respectively added to the base liquid in the first reaction container containing the base liquid by continuous feeding to carry out a co-precipitation reaction. When the precipitate reaches a first predetermined particle size, the feeding of the interface inducing agent solution is stopped to obtain an initial slurry;

[0036] S3, returning the initial slurry after the first dense concentration treatment to the first reaction container to be mixed with the metal mixed salt solution, the complexing agent solution and the precipitant solution added to the first reaction container to continue the co-precipitation reaction, and stopping the first dense concentration treatment when the precipitate reaches a second predetermined particle size to obtain an intermediate slurry;

[0037] S4, overflowing the intermediate slurry into the second reaction container, and returning the intermediate slurry overflowing in the second reaction container to the first reaction container after the second dense concentration treatment to be mixed with the metal mixed salt solution, complexing agent solution and precipitant solution added into the first reaction container to continue the precipitation reaction, and the solid content of the slurry formed after the second dense concentration treatment being returned is the same as the solid content of the slurry in the first reaction container being received, and when the precipitate reaches a third predetermined particle size, stop conveying the slurry formed after the second dense concentration treatment to the first reaction container, and stop adding the metal mixed salt solution, complexing agent solution and precipitant solution, so as to obtain a qualified slurry;

[0038] S5. Filter and wash the qualified slurry to obtain a ternary positive electrode material precursor.

[0039] The first aspect of the present application provides a method for preparing a ternary positive electrode material precursor. First, a seed crystal of the precursor is prepared by a coprecipitation reaction. When the precipitate reaches a first predetermined particle size, a first dense concentration treatment is performed, so that the solid content in the precursor slurry in the first reaction container gradually increases, so that the coprecipitation reaction enters a seed crystal stabilization period; after the precipitate reaches a second predetermined particle size, the first dense concentration treatment is stopped, the slurry in the first reaction container overflows into the second reaction container, and the precursor material in the second reaction container is concentrated by a thickener, and the concentrated slurry in the thickener is transported back to the reaction container. The first reaction container is provided, and the solid content of the slurry after the first dense concentration treatment is controlled to be the same as the solid content of the slurry in the first reaction container when the slurry returned after the second dense concentration treatment is received, so as to ensure that the precursor slurry in the first reaction container has a stable solid content. Under the condition of a certain solid content, the growth rate of the precursor in the first reaction container can be approximately uniform, so that the crystal structure of the precursor can be regulated, and the purpose of controlling the arrangement and stacking of the primary particles of the ternary positive electrode material precursor can be achieved, thereby preparing precursor particles with high tap density, good sphericity and regular primary particle size.

[0040] The embodiment of the present application adopts a staged continuous precipitation reaction method. By monitoring the particle size of the slurry during the reaction, the initial slurry is added back to the first reaction container after the first dense concentration treatment for continued growth, and then the reaction slurry after the first dense concentration treatment overflows into the second reaction container, and then the slurry after the second dense concentration treatment is added back to the first reaction container for continued growth until the precipitate reaches a predetermined particle size, so that the growth conditions of large and small particles of the prepared precursor particles are the same and the growth cycles are close, thereby preparing precursor particles with consistent crystal structure.

[0041] In some embodiments, in step S1, the molar concentration of the metal ions in the metal mixed salt solution is 1.5-2.5 mol / L. The metal mixed salt solution is a soluble inorganic salt mixed solution of nickel ions, cobalt ions and manganese ions. The embodiment of the present application adjusts the concentration of the metal mixed salt solution to regulate the granulation speed and growth speed of the precursor grains. Within this concentration range, it is beneficial for each metal raw material to fully contact and react with the complexing agent and the precipitant to generate a precursor crystal nucleus. Specifically, the total molar concentration of the nickel source, cobalt source and manganese source in the metal mixed salt solution can be 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.3 mol / L, 2.5 mol / L and other typical but non-limiting values.

[0042] In some embodiments, in step S1, the molar concentration of the precipitant solution is 5-12 mol / L. The precipitant can react with metal ions to generate a ternary cathode material precursor. The embodiment of the present application can adjust the growth rate of the precursor crystal nucleus by optimizing and controlling the concentration of the precipitant solution. If the concentration is too low, it is not conducive to the contact reaction between the various metal raw material components and the precipitant to form a crystal nucleus; if the concentration is too high, it will cause premature nucleation of the grains, which is not conducive to the control of the precursor crystal structure. Specifically, the molar concentration of the precipitant solution can be 5 mol / L, 7 mol / L, 8 mol / L, 10 mol / L, 12 mol / L and other typical but non-limiting values.

[0043] In some embodiments, in step S1, the molar concentration of the complexing agent solution is 4-8 mol / L. During the coprecipitation reaction, the metal ions first undergo a complexation reaction with the complexing agent, and then undergo a coprecipitation reaction with the precipitant to generate a nickel-cobalt-manganese ternary positive electrode material precursor. The embodiment of the present application adjusts the concentration of the complexing agent solution so that the coprecipitation reaction proceeds slowly, thereby adjusting the growth rate of the precursor crystal nucleus, and then obtaining a regular, dense, and uniform arrangement of primary particles. Specifically, the molar concentration of the complexing agent solution can be typical but non-restrictive values ​​such as 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, and 8 mol / L.

[0044] In some embodiments, in step S1, the mass concentration of the interface inducer solution is 5-25g / L. It should be understood that the collective shape of the primary particles is mainly affected by the difference in interfacial energy of different crystal faces, the balance of thermodynamic and kinetic growth mechanisms. The interface inducer added in the embodiment of the present application can adjust the interfacial energy of different crystal faces, and then can regulate the main driving force of the anisotropic growth of nanoparticles, thereby obtaining a ternary positive electrode material precursor with regular arrangement of primary particles and high sphericity of secondary particles. Specifically, the mass concentration of the interface inducer solution is 5g / L, 8g / L, 12g / L, 15g / L, 20g / L, 25g / L and other typical but non-limiting values.

[0045] In some embodiments, in step S1, the interface inducer is at least one of sodium glutamate, sodium arginine and sodium glycine. The preferred interface inducer molecules of the present application embodiment have both acidic -COOH and basic functional groups -NH2, can be ionized in water, have strong hydrophilicity and chelation, can encapsulate nickel ions, and improve the stability of nickel ions in solution. Further, the nickel ions complexed by the interface inducer will repel water molecules, thereby promoting the desolvation process of hydrated nickel ions, reducing the nucleation barrier, and limiting the diffusion of nickel ions, preferentially forming nickel hydroxide, and then gradually adsorbing cobalt and manganese to form nickel-cobalt-manganese composite hydroxides. In this process, the growth advantage crystal plane (101 crystal plane) of nickel hydroxide will be highlighted, thereby achieving the purpose of refining primary particles.

[0046] In some embodiments, in step S1, the precipitant is at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide. The preferred precipitant of the present application can ensure the complete coprecipitation reaction and is conducive to promoting the formation and precipitation of crystal nuclei.

[0047] In some embodiments, in step S1, the complexing agent is at least one of ammonia water, ammonium chloride and ammonium sulfate. The ammonium ions provided by the preferred complexing agent of the present application can react with metal ions to adjust the growth rate of the precursor nucleus, thereby obtaining precursor particles with regular primary particle arrangement and stable formation.

[0048] In some embodiments, in step S1, the metal mixed salt solution is at least one of sulfate, chloride and nitrate.

[0049] In some embodiments, in step S1, the molar ratio of nickel ions, cobalt ions and manganese ions in the metal mixed salt solution is 40-98: 1-30: 1-40. The present application regulates the molar ratio of nickel ions, cobalt ions and manganese ions in the metal mixed salt solution to obtain the desired precursor by coprecipitation reaction.

[0050] In some embodiments, in step S2, the first predetermined particle size D50 is 3-6 μm. The solid content in the initial slurry is 30-70 g / L. When the particle size D50 to be precipitated in the initial slurry obtained by the co-precipitation reaction reaches the first predetermined particle size, the addition of the interface inducer solution is stopped, and the solid content of the slurry is 30-70 g / L. D50 represents the particle size corresponding to 50% of the cumulative particle size distribution percentage of a sample. The preferred range of the first predetermined particle size D50 in the embodiment of the present application is conducive to the subsequent reaction. If the first predetermined particle size is too small, it will affect the assembly structure of the primary particles, and then affect the initial charge and discharge performance and cycle performance of the prepared battery; if the first predetermined particle size is too large, the size of the primary particles will be too large, which is not conducive to the regular arrangement on the surface of the secondary particles, and then affect the effective operating temperature of the battery.

[0051] In some embodiments, in step S2, the metal mixed salt solution, the precipitant solution, the complexing agent solution and the interface inducing agent solution are fed independently. The embodiment of the present application adopts a continuous feeding method to make the precipitation reaction continue, continuously react to generate new precursors and make the generated precursors maintain a certain particle size growth rate, so that the growth conditions of the precursors are the same and the growth cycles are close, thereby ensuring the consistency of the growth of the ternary positive electrode material precursor.

[0052] In some embodiments, in step S2, the feeding rate ratio of the interface inducing agent solution to the metal mixed salt solution is 0.02-0.1:1. The feeding rate ratio of the metal mixed salt solution, the precipitant solution and the complexing agent solution is 0.4-0.67:0.17-0.4:0.03-0.063. The embodiment of the present application regulates the flow rate of each component so that the molar amount of the metal mixed salt solution, the precipitant solution and the complexing agent solution per unit time conforms to the stoichiometric ratio of the precipitation reaction. For example, the molar amount of the metal mixed salt solution, the precipitant solution and the complexing agent solution per unit time is 1:2:0.25, thereby achieving the regulation of the growth rate of the precursor grains.

[0053] In some embodiments, in step S2, the base liquid includes: the mass concentration of ammonium ions is 2-5g / L, the mass concentration of the interface inducer is 0.5-2.5g / L, and the pH is 11-12. The embodiment of the present application can better control the coprecipitation reaction process by adding the base liquid, which is conducive to the uniform dispersion and mixing of the components, provides a buffering effect, and prepares precursor particles with high tap density, good sphericity, and regular primary particle size. The concentration of ammonium ions added in the base liquid makes the structure of the prepared precursor particles more compact. Specifically, the mass concentration of ammonium ions in the base liquid can be typical but non-limiting values ​​such as 2g / L, 3g / L, 4g / L, and 5g / L. The mass concentration of the interface inducer can be typical but non-limiting values ​​such as 0.5g / L, 1g / L, 1.5g / L, and 2.5g / L. Specifically, the pH value in the base liquid can be 11-11.2, 11.5-11.7, 11.8-12, etc.

[0054] In some embodiments, in step S2, the volume of the base liquid is 1 / 3-1 / 2 of the effective volume of the first reaction container. Specifically, the amount of base liquid added can be typical but non-limiting values ​​such as 1 / 3, 2 / 5, 1 / 2 of the effective volume of the first reaction container.

[0055] In some embodiments, in step S2, the conditions of the coprecipitation reaction are: temperature of 50-70°C, time of 6-10h, pH of 11-12, stirring speed of 220-300rpm, and mass concentration of ammonium ions of 2-5g / L. During the coprecipitation reaction, by controlling the reaction time, pH, stirring speed and concentration of ammonium ions, the stability of the reaction system is ensured, thereby fully ensuring the formation effect and quality of the ternary cathode material precursor, and being conducive to obtaining precursor particles with high tap density, good sphericity and regular primary particle size. Specifically, the reaction time can be 6h, 8h, 10h, etc., the stirring speed can be 220rpm, 250rpm, 300rpm, etc., the concentration of ammonium ions can be 2g / L, 4g / L, 5g / L, etc., and the pH value is preferably 11-11.2.

[0056] Specifically, the reaction is regulated by monitoring the D50 particle size of the precipitate during the coprecipitation reaction, and the pH value during the coprecipitation reaction can be regulated by the feeding rate of the precipitant solution, and the mass concentration of ammonium ions can be regulated by the feeding rate of the complexing agent solution.

[0057] In some embodiments, in step S2, the protective atmosphere is selected from at least one of argon atmosphere, helium atmosphere, and nitrogen atmosphere. Providing a protective atmosphere is beneficial to preventing metal raw materials such as nickel source, cobalt source, and manganese source from being oxidized, ensuring that no impurities are introduced during the co-precipitation reaction, and ensuring that the crystal nucleus purity of the obtained ternary positive electrode material precursor is high.

[0058] In some embodiments, in step S3, the second predetermined particle size D50 is 5-10 μm, and the solid content of the slurry after the first dense concentration treatment is 120-250 g / L. After the initial slurry is treated with the first dense concentration, it is returned to the first reactor to continue the coprecipitation reaction. When the precipitate reaches the second predetermined particle size, the first dense concentration treatment is stopped, and the solid content in the slurry is 120-250 g / L. By densely concentrating the initial slurry, the solid content in the slurry is gradually increased, so that the coprecipitation reaction enters the seed stabilization period, which is conducive to the assembly of primary particles into spherical secondary particles.

[0059] In some embodiments, in step S4, the third predetermined particle size D50 is 8-18 μm. The target value of the third predetermined particle size D50 preferred in the embodiment of the present application ensures the reactivity and tap density of the ternary positive electrode precursor material. Figure 4 , which is a schematic diagram of the particle size distribution of the ternary cathode material precursor prepared in Example 1. Specifically, the morphology of the ternary cathode material precursor prepared in Example 1 under an electron microscope is as follows: Figure 1As shown, the secondary particles of the ternary positive electrode material precursor are spherical, and the primary particles on the surface of the secondary spherical particles are arranged regularly and in rows, especially the primary particles are alternated in an orderly manner and leave certain gaps.

[0060] In some embodiments, in step S4, the solid content of the slurry in the first reaction container when receiving the slurry returned after the second dense concentration treatment is 120-250 g / L. The present application can adjust the flow rate of the slurry returned to the first reaction container after the second dense concentration treatment by setting the solid content of the slurry in the first reaction container when receiving the slurry returned after the second dense concentration treatment, thereby stably controlling the solid content of the slurry in the first reaction container, so that the growth rate of the precursor in the first reaction container can be approximately uniform, thereby achieving the purpose of controlling the crystal structure of the precursor and the arrangement and sphericity of the primary particles.

[0061] In some embodiments, the method for preparing a ternary positive electrode material precursor also includes step S6, after obtaining qualified slurry, exchanging the roles of the first reaction container and the second reaction container, and adding a metal mixed salt solution, a complexing agent solution and a precipitant solution to the second reaction container in a protective atmosphere by continuous feeding to carry out a co-precipitation reaction, and repeating the overflow and second dense concentration steps until the precipitate of the slurry in the second reaction container reaches a third predetermined particle size.

[0062] It should be noted that, in the embodiment of the present application, in steps S1-S5, the function of the first reaction container is mainly to carry out a co-precipitation reaction to obtain a slurry of a predetermined particle size, and the function of the second reaction container is to receive the slurry overflowing after the first dense concentration treatment, and then carry out a second dense concentration treatment on the received slurry overflowing after the first dense concentration treatment and return it to the first reaction container to continue the precipitation reaction, that is, the second reaction container mainly serves as an overflow container.

[0063] In the embodiment of the present application, the preparation process of the ternary positive electrode material precursor is a cyclic process. After qualified slurry is obtained in the first reaction container, the roles of the first reaction container and the second reaction container are exchanged. In other words, the second reaction container is subjected to a co-precipitation reaction, and the first reaction container is used to receive the slurry overflowing after the first dense concentration treatment.

[0064] It should be noted that the first reaction container and the second reaction container for adding the four reactants can be reactors commonly used in current production, and the size can be 5-10m 3, or it can be an improved reactor. For example, the first reactor is provided with a feed port for each of the four solutions of metal mixed salt solution, precipitant solution, complexing agent solution and interface inducing agent, and the feed ports of the four solutions and the inlet port of the protective gas are independently set; in addition, a feed port connected to a thickener is also provided, and an overflow port with a piston is provided on the upper left of the feed port. In a specific embodiment of the present application, after the precipitation reaches the second predetermined particle size, the precursor liquid in the first reaction container overflows directly from the overflow port of the first reaction container to the second reaction container, and the slurry in the second reaction container is returned to the first reaction container through the pipeline connected to the thickener after the first thickening treatment, so that the co-precipitation reaction is carried out in a staged continuous reaction. At the same time, the four solutions of metal mixed salt solution, precipitant solution, complexing agent solution and interface inducing agent are fed independently, and the four solutions do not contact each other before reaching the reaction container, so as to avoid the reaction liquid from reacting prematurely to generate impurities before reaching the reaction container due to mixed feeding. Further, the protective gas is continuously introduced into the reactor in the form of airflow, and the protective gas is independently introduced. The reaction container has a certain sealing property. After the protective gas is continuously introduced, a certain positive pressure can be formed inside the reaction container to prevent the outside air from entering, so as to prevent the reaction liquid in the reaction container from contacting with the air and then being oxidized. In the specific embodiment of the present application, the feeding position of the metal mixed salt solution, complexing agent solution, precipitant solution and interface inducing agent and the feeding port of the slurry returned to the first reaction container are all located at the upper end of the bottom blade of the first reaction container, located at the same horizontal position, and have the same tube type, are evenly distributed with each other, and the angle between the two is 72°. It can be understood that the structures of the first reaction container and the second reaction container can be consistent, and the role conversion can be realized to realize the cyclical coprecipitation reaction.

[0065] The second aspect of the embodiment of the present application provides a ternary cathode material precursor, which is prepared by the preparation method of the ternary cathode material precursor provided by the first aspect of the present application. The precursor is a micron-sized secondary spherical particle formed by assembling primary particles, and the primary particles on the surface of the secondary particles are arranged regularly and in rows, and in particular, the primary particles are alternately arranged in an orderly manner and have certain gaps.

[0066] Compared with the prior art ternary cathode material precursors in which large flake or thick strip primary particles are directly agglomerated to form secondary spherical particles, the primary particles on the surface of the secondary spherical particles of the ternary cathode material precursor product provided by the present invention are arranged regularly and in rows, and in particular, gaps are generated between the primary particles, thereby increasing the lithium ion diffusion channel. When this ternary cathode material precursor is used to make the cathode material of a lithium ion battery, it can significantly improve the initial charge and discharge performance, cycle performance and effective operating temperature range of the lithium ion battery.

[0067] In some embodiments, the ternary cathode material precursor is formed by stacking primary particles of nano-scale fine needles with a length of 200-600nm and a width of 50-150nm, and the particles are spherical structures. The ternary cathode material precursor prepared in this application has the advantages of excellent properties and simple synthesis, is suitable for mass production, and is suitable for a wide temperature range environment. It is suitable for general commercial ternary cathode materials and has certain commercial prospects.

[0068] A third aspect of an embodiment of the present application provides a positive electrode material, which is prepared by mixing a ternary positive electrode material precursor of the present application with a lithium salt.

[0069] Because the primary particles on the surface of the secondary spherical particles of the ternary positive electrode material precursor product of this application are arranged regularly and in rows, especially the alternation between the primary particles is orderly and has certain gaps, which is beneficial to the ternary positive electrode material precursor in the mixed lithium roasting process, promoting the transmission of lithium ions, and accelerating the mass transfer of lithium ions inside the particles during charging and discharging. More ions reach the particle surface per unit time, allowing lithium ions to be quickly embedded and removed, thereby having high electronic conductivity and ionic conductivity, thereby improving the capacity of the positive electrode material. In addition, the lattice dimension anisotropy of the orderly grown nano-scale needle-shaped primary particles will be improved, and the dense and orderly structure forms a stable interface during the charging and discharging process, which can effectively offset the anisotropic contraction and expansion of the primary particles caused by temperature changes or voltage changes. The increase in internal stress caused by the expansion and avoidance of the electrolyte to the inside of the particles; on the other hand, smaller grains have a larger grain boundary contact area, and the internal stress can be more evenly dispersed, thereby inhibiting the rapid formation of cracks, greatly improving the stability of the positive electrode material.

[0070] A fourth aspect of an embodiment of the present application provides a secondary battery, comprising the positive electrode material of the present application.

[0071] The secondary battery provided by the present application includes a positive electrode material prepared using the ternary positive electrode material precursor of the present application, so that the lithium-ion battery has excellent initial charge and discharge performance, cycle performance, and effective operating temperature range, and can meet the use requirements in high-cold and high-heat areas.

[0072] The following describes the invention in conjunction with specific embodiments.

[0073] Example 1

[0074] The embodiments of the present application provide a ternary cathode material precursor and a method for preparing the same.

[0075] A method for preparing a ternary cathode material precursor comprises the following steps:

[0076] S1. Prepare the following solution:

[0077] Metal mixed salt solution: obtained by dissolving nickel sulfate, cobalt sulfate and manganese sulfate in water; wherein the total molar concentration of the three elements of nickel, cobalt and manganese is 2 mol / L, and the molar ratio of nickel, cobalt and manganese is 80:10:10.

[0078] Complexing agent solution: obtained by adding ammonia water into water, with a molar concentration of 7 mol / L.

[0079] Precipitant solution: obtained by dissolving sodium hydroxide in water, with a molar concentration of 11 mol / L.

[0080] Interfacial inducer solution: Sodium glutamate is dissolved in water, and its mass concentration is 10 g / L.

[0081] S2. In a nitrogen atmosphere, the metal mixed salt solution, complexing agent solution, precipitant solution and interface inducer solution prepared in the above step S1 are fed at a uniform speed by metering pumps respectively, and are added into the first reaction container containing a base liquid (the volume of the base liquid is 1 / 3 of the effective volume of the first reaction container, the base liquid contains sodium hydroxide, ammonia water and sodium glutamate, wherein the mass concentration of ammonium ions is 2g / L, the mass concentration of sodium glutamate is 2.5g / L, and the pH of the base liquid is 11-11.2) for coprecipitation reaction, and the interface inducer solution is added into the first reaction container for coprecipitation reaction. The feeding speed ratio of the mixed metal salt solution is 0.1:1, the feeding speed ratio of the mixed metal salt solution, the precipitant solution and the complexing agent solution is 0.5:0.18:0.04, and the conditions for controlling the coprecipitation reaction are: temperature of 60°C, pH of 11-11.2, stirring speed of 220rpm, ammonium ion concentration of 4.5-5g / L, and when the particle size D50 of the precipitate reaches 4.5μm, the feeding of the interface inducing agent solution is stopped to obtain an initial slurry, and the solid content in the initial slurry is 60g / L;

[0082] S3, conveying the initial slurry obtained in the above step S2 to a thickener for a first dense thickening treatment, and then returning the slurry after the first dense thickening treatment to the first reaction container to continue the co-precipitation reaction with the metal mixed salt solution, complexing agent solution, and precipitant solution being added in the first reaction container. When the particle size D50 of the precipitate reaches 8 μm, stop the first dense thickening treatment, and stop conveying the slurry after the first dense thickening treatment to the first reaction container. At this time, the solid content of the slurry in the first reaction container is 200 g / L;

[0083] S4, overflow the slurry with a solid content of 200 g / L in the first reaction container after the above step S3 to the second reaction container, and transport the slurry overflowing in the second reaction container to the thickener for second dense thickening treatment, and then return the concentrated slurry after the second dense thickening treatment to the first reaction container to continue the precipitation reaction (at this time, the returned slurry has the same solid content as the slurry in the first reaction container that is receiving the returned slurry), and adjust the flow rate from the thickener to the first reactor container by monitoring the solid content in the first reaction container, wherein the solid content of the slurry in the first reaction container is set to 200 g / L, and when the particle size D50 of the precipitate reaches 12 μm, stop transporting the slurry after the second dense thickening treatment to the first reaction container, and stop adding the metal mixed salt solution, the complexing agent solution and the precipitant solution, to obtain and collect the qualified slurry after the reaction;

[0084] S5. The qualified slurry is filtered, washed, dried, batched, sieved, and demagnetized to obtain a ternary positive electrode material precursor.

[0085] A ternary positive electrode material precursor is prepared by the above preparation method.

[0086] The particle size D50 of the prepared ternary cathode material precursor was 12.0 μm and the specific surface area was 10.8 m 2 / g, tap density is 2.08g / cm 3 .

[0087] Example 2

[0088] The embodiments of the present application provide a ternary cathode material precursor and a method for preparing the same.

[0089] A method for preparing a ternary cathode material precursor comprises the following steps:

[0090] S1. Prepare the following solution:

[0091] Metal mixed salt solution: obtained by dissolving nickel sulfate, cobalt sulfate and manganese sulfate in water; wherein the total molar concentration of nickel, cobalt and manganese is 2.5 mol / L, and the molar ratio of nickel, cobalt and manganese is 80:10:10;

[0092] Complexing agent solvent: obtained by adding ammonia water into water, with a molar concentration of 8 mol / L;

[0093] Precipitant solution: obtained by dissolving sodium hydroxide in water, with a molar concentration of 8 mol / L;

[0094] Interfacial inducer solution: obtained by dissolving sodium arginine in water, with a mass concentration of 15 g / L.

[0095] S2. In a nitrogen atmosphere, the metal mixed salt solution, complexing agent solution, precipitant solution and interface inducer solution prepared in the above step S1 are fed at a uniform speed respectively by metering pumps, and are simultaneously added into the first reaction container containing a base liquid (the volume of the base liquid is 1 / 3 of the effective volume of the first reaction container, and the base liquid is a mixed solution including sodium hydroxide, ammonia water and sodium arginine, wherein the mass concentration of ammonium ions is 3 g / L, the mass concentration of sodium arginine is 1.5 g / L, and the pH is 11-11.2) for coprecipitation reaction. The interface inducer The feeding speed ratio of the solution to the metal mixed salt solution is 0.05:1, the feeding speed ratio of the metal mixed salt solution, the precipitant solution and the complexing agent solution is 0.4:0.25:0.03, and the conditions for controlling the coprecipitation reaction are: temperature of 55°C, pH of 11-11.2, stirring speed of 250rpm, ammonium ion concentration of 3-3.5g / L, and when the particle size D50 of the precipitate reaches 4μm, the feeding of the interface inducing agent solution is stopped to obtain an initial slurry, and the solid content in the initial slurry is 60g / L;

[0096] S3, conveying the initial slurry obtained in the above step 2 to a thickener for a first dense thickening treatment, and then returning the slurry after the first dense thickening treatment to the first reaction container to continue the co-precipitation reaction with the metal mixed salt solution, complexing agent solution, and precipitant solution being added in the first reaction container. When the particle size D50 of the precipitate reaches 6.5 μm, stop the first dense thickening treatment, and stop conveying the slurry after the first dense thickening treatment to the first reaction container. At this time, the solid content of the slurry in the first reaction container is 180 g / L;

[0097] S4, after the completion of the above step S3, the slurry with a solid content of 180 g / L in the first reaction container overflows into the second reaction container, and the slurry overflowing in the second reaction container is transported to the thickener for the second dense thickening treatment, and then the concentrated slurry after the second dense thickening treatment is returned to the first reaction container to continue the precipitation reaction (at this time, the returned slurry has the same solid content as the slurry in the first reaction container that is receiving the returned slurry), and the flow rate from the thickener to the first reactor container is adjusted by monitoring the solid content in the first reaction container, wherein the solid content of the slurry in the first reaction container is set to 180 g / L, and when the particle size D50 of the precipitate reaches 10 μm, the slurry transported after the second dense thickening treatment to the first reaction container is stopped, and the addition of the metal mixed salt solution, the complexing agent solution and the precipitant solution is stopped, and the qualified slurry after the reaction is completed is obtained and collected;

[0098] S5. The qualified slurry is filtered, washed, dried, batched, sieved, and demagnetized to obtain a ternary positive electrode material precursor.

[0099] A ternary positive electrode material precursor is prepared by the above preparation method.

[0100] The particle size D50 of the prepared ternary cathode material precursor was 10.0 μm and the specific surface area was 10.1 m 2 / g, tap density is 2.0g / cm 3 .

[0101] Example 3

[0102] The embodiments of the present application provide a ternary cathode material precursor and a method for preparing the same.

[0103] A method for preparing a ternary cathode material precursor comprises the following steps:

[0104] S1. Prepare the following solution:

[0105] Metal mixed salt solution: obtained by dissolving nickel sulfate, cobalt sulfate and manganese sulfate in water; wherein the total molar concentration of nickel, cobalt and manganese is 1.5 mol / L, and the molar ratio of nickel, cobalt and manganese is 80:10:10;

[0106] Complexing agent solvent: obtained by adding ammonia water into water, with a molar concentration of 4 mol / L;

[0107] Precipitant solution: obtained by dissolving sodium hydroxide in water, with a molar concentration of 5 mol / L;

[0108] Interfacial inducer solution: Sodium glycinate is dissolved in water, and its mass concentration is 20 g / L.

[0109] S2. In a nitrogen atmosphere, the metal mixed salt solution, complexing agent solution, precipitant solution and interface inducer solution prepared in the above step S1 are fed at a uniform speed respectively by metering pumps, and are simultaneously added into the first reaction container containing a base liquid (the volume of the base liquid is 1 / 2 of the effective volume of the first reaction container, and the base liquid is a mixed solution of sodium hydroxide, ammonia water and sodium glycinate, wherein the mass concentration of ammonium ions is 2 g / L, the mass concentration of sodium glycinate is 0.5 g / L, and the pH is 11-11.2) for coprecipitation reaction. The interface inducer The feeding speed ratio of the solution to the metal mixed salt solution is 0.02:1, the feeding speed ratio of the metal mixed salt solution, the precipitant solution and the complexing agent solution is 0.67:0.4:0.06, and the conditions for controlling the coprecipitation reaction are: temperature of 65°C, pH of 11-11.2, stirring speed of 300rpm, ammonium ion concentration of 4.5-5g / L, when the particle size D50 of the precipitate reaches 5μm, stop feeding the interface inducing agent solution to obtain an initial slurry, and the solid content in the initial slurry is 60g / L;

[0110] S3, conveying the initial slurry obtained in the above step S2 to a thickener for a first dense thickening treatment, and then returning the slurry after the first dense thickening treatment to the first reaction container to continue the co-precipitation reaction with the metal mixed salt solution, complexing agent solution, and precipitant solution being added in the first reaction container. When the particle size D50 of the precipitate reaches 8.5 μm, stop the first dense thickening treatment, and stop conveying the slurry after the first dense thickening treatment to the first reaction container. At this time, the solid content of the slurry in the first reaction container is 210 g / L;

[0111] S4, after the completion of the above step S3, the slurry with a solid content of 210 g / L in the first reaction container overflows into the second reaction container, and the slurry overflowing in the second reaction container is transported to the thickener for the second dense thickening treatment, and then the concentrated slurry after the first dense thickening treatment is returned to the first reaction container to continue the precipitation reaction (at this time, the returned slurry has the same solid content as the slurry in the first reaction container that is receiving the returned slurry), and the flow rate from the thickener to the first reactor container is adjusted by monitoring the solid content in the first reaction container, wherein the solid content of the slurry in the first reaction container is set to 210 g / L, and when the particle size D50 of the precipitate reaches 11 μm, the slurry after the second dense thickening treatment is stopped from being transported to the first reaction container, and the addition of the metal mixed salt solution, the complexing agent solution and the precipitant solution is stopped, and the qualified slurry after the reaction is completed is obtained and collected;

[0112] S5. The qualified slurry is filtered, washed, dried, batched, sieved, and demagnetized to obtain a ternary positive electrode material precursor.

[0113] A ternary positive electrode material precursor is prepared by the above preparation method.

[0114] The particle size D50 of the prepared ternary cathode material precursor was 11.0 μm and the specific surface area was 9.2 m 2 / g, tap density is 2.13g / cm 3 .

[0115] Comparative Example 1

[0116] This comparative example provides a ternary positive electrode material precursor and a preparation method thereof.

[0117] A ternary cathode material precursor Ni 0.80 Co 0.10 Mn 0.10 (OH)2. The preparation method of the ternary cathode material precursor is different from that of Example 1 in that: in step S1, no interface inducer solution is prepared, in step S2, no interface inducer solution is added during the coprecipitation reaction, and the base solution does not include an interface inducer.

[0118] Comparative Example 2

[0119] This comparative example provides a ternary positive electrode material precursor and a preparation method thereof.

[0120] A ternary cathode material precursor Ni 0.80 Co 0.10 Mn 0.10 (OH)2. The preparation method of the ternary positive electrode material precursor is different from that of Example 1 in that steps S3 and S4 are replaced by: the initial slurry with a solid content of 60 g / L obtained in step S2 overflows into the second reaction container, and the slurry overflowing in the second reaction container is transported to a thickener for thickening treatment, and then the slurry concentrated after the thickening treatment is returned to the first reaction container to continue the precipitation reaction (at this time, the returned slurry has the same solid content as the slurry in the first reaction container that is receiving the returned slurry), and the flow rate from the thickener to the first reactor container is adjusted by monitoring the solid content in the first reaction container, wherein the solid content in the first reaction container is set to 200 g / L, and when the particle size D50 of the precipitate reaches 12 μm, the thickening treatment of the slurry to the first reaction container is stopped, and the addition of the metal mixed salt solution, the complexing agent solution and the precipitant solution is stopped, and the qualified slurry after the reaction is completed is obtained and collected.

[0121] Comparative Example 3

[0122] This comparative example provides a ternary positive electrode material precursor and a preparation method thereof.

[0123] A ternary cathode material precursor Ni 0.80 Co 0.10 Mn 0.10 (OH)2. The method for preparing the ternary cathode material precursor is different from that of Example 1 in that the solid content of the slurry in the first reaction container in step S4 is set to 500 g / L.

[0124] Cathode Material:

[0125] The ternary positive electrode material precursors prepared in Examples 1-3 and Comparative Examples 1-3 are respectively mixed with lithium salt to prepare positive electrode materials, which specifically includes the following steps:

[0126] The ternary positive electrode material precursors prepared in Examples 1-3 and Comparative Examples 1-3 were respectively mixed with lithium hydroxide at a molar ratio of 1:1.05 to obtain a mixed material;

[0127] The mixed material is sintered at 750° C. to obtain a positive electrode material.

[0128] Secondary battery

[0129] The positive electrode materials prepared in Examples 1-3 and Comparative Examples 1-3 are used as positive electrodes of secondary batteries, and the secondary batteries are assembled into batteries according to the following method: 18650.

[0130] Performance testing and result analysis

[0131] (1) Taking the ternary positive electrode material precursors prepared in Examples 1-2 and Comparative Example 1 as examples, the SEM images of the ternary positive electrode material precursors obtained were analyzed respectively. Figure 1 is a SEM image of the ternary cathode material precursor provided in Example 1 of the present application, Figure 2 is a SEM image of the ternary cathode material precursor provided in Example 2 of the present application, Figure 3 This is the SEM image of the ternary positive electrode material precursor provided in Comparative Example 1 of the present application. It can be seen that the ternary positive electrode material precursor of Examples 1-2 is assembled from nano-scale fine needle-shaped primary particles to form micron-scale secondary spherical particles. The primary particles on the surface of the secondary spherical particles are arranged regularly, densely and uniformly, especially the primary particles are alternately arranged in an orderly manner and have certain gaps. The ternary positive electrode material precursor of Comparative Example 1 is also a spherical particle, but the primary particles on the surface of the secondary spherical particles are larger in size and loosely arranged.

[0132] further, Figure 4 This is the particle size distribution diagram of the ternary positive electrode material precursor provided in Example 1 of the present application. It can be seen that the ternary positive electrode material precursor obtained in Example 1 has a narrow particle size distribution, and the crystal form, structure and size of the precursor particles are basically consistent, which is conducive to assembling into spherical precursor particles with high tap density and good sphericity.

[0133] (2) The secondary batteries prepared in Examples 1-3 and Low Ratio 1-3 were subjected to the following performance tests, and the results are shown in Table 1 below.

[0134] Performance test: At room temperature (25°C), the above battery was subjected to a 0.1C charge and 0.1C discharge cycle test in the range of 3.0-4.25V, and the cycle discharge capacity was recorded.

[0135] High temperature storage test: At room temperature, fully charge the above batteries and place them in an oven with a set temperature. After standing for a set time, wait for the batteries to cool to room temperature before performing charge and discharge tests and recording the battery capacity retention rate.

[0136] Low temperature discharge test: At room temperature, fully charge the above batteries and place them in a set temperature oven. Set the temperature of the low temperature oven. After reaching the set temperature, put the fully charged batteries in. After the batteries return to room temperature, perform charge and discharge tests and record the battery capacity retention rate.

[0137] Table 1

[0138]

[0139] From the test results of Examples 1-3 and Comparative Examples 1-3 in Table 1, it can be seen that the cycle performance and discharge capacity of the lithium ion battery prepared in Examples 1-3 are much higher than those in Comparative Examples 1-3, and still have excellent capacity retention under low temperatures such as -20°C or high temperatures such as 80°C, meeting the use requirements in high-cold and high-heat areas. Compared with Comparative Example 1, the interface inducer added in Example 1 can effectively adjust the interface energy of different crystal faces of the precursor particles, thereby adjusting the growth and arrangement of the precursor particles, and can also reduce the nucleation energy barrier, achieve the refinement of the primary particles, and thus improve the discharge capacity and effective operating temperature range of the lithium ion battery. Relative to Comparative Example 2, Example 1 first performs a first dense concentration treatment on the obtained initial slurry to increase the solid content in the slurry, so that the reaction enters the seed stabilization period, and then overflows, so that the crystal structure of the precursor can be regulated, so that the dense and orderly structure of the lithium ion battery during the charge and discharge process forms a stable interface, which can effectively offset the damage to the battery caused by temperature changes. Compared with Comparative Example 3, Example 1 adjusts the flow rate of the slurry delivered to the first reaction container after the second dense concentration treatment by setting the solid content of the slurry in the first reaction container. Under the condition that the slurry in the first reaction container is stable, the growth rate of the precursor in the first reaction container can be approximately uniform, thereby achieving the regulation of the crystal structure of the precursor, so that the lithium-ion battery meets the use requirements of high-cold and high-heat areas.

[0140] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a ternary cathode material precursor, characterized in that: The following steps are involved: A metal mixed salt solution, a complexing agent solution, a precipitant solution and an interface inducing agent solution are prepared respectively, wherein the metal mixed salt solution contains nickel, cobalt and manganese; In a protective atmosphere, the metal mixed salt solution, the complexing agent solution, the precipitant solution and the interface inducer solution are added to a first reaction container containing a base solution by continuous feeding to perform a co-precipitation reaction, and when the precipitate reaches a first predetermined particle size, the feeding of the interface inducer solution is stopped to obtain an initial slurry; The initial slurry is returned to the first reaction container after the first dense concentration treatment to be mixed with the metal mixed salt solution, the complexing agent solution and the precipitant solution added to the first reaction container to continue the co-precipitation reaction, and when the precipitate reaches a second predetermined particle size, the first dense concentration treatment is stopped to obtain an intermediate slurry; The intermediate slurry overflows into the second reaction container, and the intermediate slurry overflowing in the second reaction container is returned to the first reaction container after the second dense concentration treatment to be mixed with the metal mixed salt solution, the complexing agent solution and the precipitant solution added to the first reaction container to continue the co-precipitation reaction, and the solid content of the slurry formed after the second dense concentration treatment being returned is the same as the solid content of the slurry in the first reaction container being received, and when the precipitate reaches a third predetermined particle size, the slurry formed after the second dense concentration treatment is stopped from being transported to the first reaction container, and the addition of the metal mixed salt solution, the complexing agent solution and the precipitant solution is stopped to obtain a qualified slurry; After obtaining the qualified slurry, the roles of the first reaction container and the second reaction container are exchanged, and in a protective atmosphere, the metal mixed salt solution, the complexing agent solution and the precipitant solution are added to the second reaction container in a continuous feeding manner to perform a co-precipitation reaction, and the overflow and second dense concentration steps are repeated until the precipitate of the slurry in the second reaction container reaches a third predetermined particle size, thereby obtaining a qualified slurry; The qualified slurry is filtered and washed to obtain the ternary positive electrode material precursor; Wherein, the interfacial inducer is at least one of sodium glutamate, sodium arginine and sodium glycine; and / or The precipitant is at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide; and / or The complexing agent is at least one of ammonia water, ammonium chloride and ammonium sulfate; and / or The molar ratio of nickel ions, cobalt ions and manganese ions in the metal mixed salt solution is 40-98:1-30:1-40.

2. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The molar concentration of metal ions in the metal mixed salt solution is 1.5-2.5 mol / L; and / or The molar concentration of the precipitant solution is 5-12 mol / L; and / or The molar concentration of the complexing agent solution is 4-8 mol / L; and / or The mass concentration of the interface inducing agent solution is 5-25 g / L; and / or The first predetermined particle size D50 is 3-6 μm; and / or The second predetermined particle size D50 is 5-10 μm; and / or The third predetermined particle size D50 is 8-18 μm; and / or The solid content in the initial slurry is 30-70 g / L; and / or The solid content of the slurry after the first dense concentration treatment is 120-250 g / L.

3. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The feeding speed ratio of the interface inducing agent solution to the metal mixed salt solution is 0.02-0.1:1; and / or The feeding speed ratio of the metal mixed salt solution, the precipitant solution and the complexing agent solution is 0.4-0.67:0.17-0.4:0.03-0.

063.

4. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The base solution comprises: 2-5 g / L ammonium ions, 0.5-2.5 g / L interface inducer, and a pH of 11-12; and / or The volume of the base liquid is 1 / 3-1 / 2 of the effective volume of the first reaction container; and / or The conditions of the coprecipitation reaction are: temperature of 50-70° C., pH of 11-12, stirring speed of 220-300 rpm, and mass concentration of ammonium ions of 2-5 g / L.

5. A ternary cathode material precursor, characterized in that: The ternary positive electrode material precursor is prepared by the preparation method of any one of claims 1 to 4.

6. The ternary cathode material precursor according to claim 5, characterized in that: The ternary positive electrode material precursor is formed by stacking nano-scale fine needle-shaped primary particles with a length of 200-600nm and a width of 50-150nm, and the particles are spherical in structure.

7. A positive electrode material, characterized in that: The positive electrode material is prepared by mixing a ternary positive electrode material precursor prepared by the preparation method according to any one of claims 1 to 4 with a lithium salt.

8. A secondary battery, characterized in that: The secondary battery comprises the positive electrode material according to claim 7.

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