Ternary precursor, preparation method thereof and cathode material

Abstract

The application provides a ternary precursor, a preparation method of the ternary precursor and a positive electrode material, and the ternary precursor is a nickel-cobalt-manganese hydroxide; the ternary precursor comprises a core layer, a connecting ring layer and a shell layer from inside to outside, the connecting ring layer is a dense structure, the core layer comprises a center layer and an intermediate layer from inside to outside, and the average thicknesses of the center layer, the intermediate layer and the shell layer are all greater than the average thickness of the connecting ring layer. The ternary precursor provided by the application is dense in structure by controlling the intermediate layer, the connecting ring layer and the shell layer to be dense in structure, so that the particle growth of the ternary precursor material is connected without a fault, the particle consistency of the ternary precursor material can be enhanced, the connecting strength and the compression resistance of the inner layer and the outer layer of the core-shell structure can be improved, and the particle structure of the ternary precursor material is more stable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a ternary precursor, a preparation method thereof and a positive electrode material. BACKGROUND

[0002] With the rapid development of the world automobile industry, green new energy vehicles gradually become the future development direction of the industry. New energy vehicles use lithium batteries as the core power. How to improve the endurance and energy storage capacity of lithium batteries, the unit volume energy density of lithium battery materials, the safety performance and service life of batteries has become the trend and the direction of technology. As an important component of the positive electrode material of lithium batteries, ternary precursor materials have always been the core of technology. In order to ensure the performance of the battery, the ternary precursor and positive electrode material products on the market are gradually developing towards high nickel and structural stability.

[0003] At present, the high-nickel ternary precursor material product is mostly of core-shell structure. This ternary precursor material still has certain defects, specifically:

[0004] Generally, a porous ring layer structure is arranged at the connection of the core-shell of the ternary precursor material or the core-shell structure is arranged as a porous material with loose pore structure inside, so as to facilitate the conduction of lithium ions. At this time, the interface between the core and the shell of the ternary precursor material is provided with a porous gap ring layer connected by fine particles, that is, the ternary precursor material has a loose porous gap structure inside. When the ternary precursor material is sintered to prepare the positive electrode material, the fine loose particles of the porous gap ring layer will migrate outward, resulting in that only particles with larger size can be used to connect the core layer and the shell layer, the internal structure of the material is not uniform, the consistency is poor, and finally a hollow structure of holes with different sizes and irregular multi-layer hollow ring layers is formed in the positive electrode material. And when the thickness of the connecting ring layer is large, the holes and the hollow structure of the multi-layer hollow ring layer formed in the positive electrode material will cause the positive electrode material to have low compaction ability, insufficient compression resistance, insufficient particle structure strength, and easy structure peeling, cracking or collapse between the grain boundaries under the conditions of high voltage or large current charging and discharging, thereby causing the capacity of the battery to be greatly attenuated during high-temperature cycling and the service life of the battery to be shortened.

[0005] Therefore, it is particularly important to make the internal structure of the material grow consistently and to arrange a stable structure of the connecting ring layer between the core layer and the shell layer which has both good compression resistance and satisfies the conduction ability of lithium ions. SUMMARY

[0006] In view of at least one of the problems of low compaction ability, insufficient compression resistance and insufficient particle structure strength of the traditional ternary precursor positive electrode material, the present application provides a ternary precursor, a preparation method thereof and a positive electrode material, which can improve the particle compression resistance and structural stability of the ternary precursor material.

[0007] According to an aspect of the present application, there is provided a ternary precursor, the chemical formula of which is Ni x Co y Mn z M a (OH)2, wherein 0.75≤x<1, 0≤y<0.18, 0≤z<0.20, 0≤a<0.1, x+y+z+a=1; M is at least one of Al, Ti, Zr, Mo, Cr, W, B, Mg, Ba, Nb and Sr.

[0008] In the above technical solution of the present application, the ternary precursor is of a core-shell structure, which specifically comprises a core layer, a connecting ring layer and a shell layer from inside to outside, wherein the core layer comprises a center layer and an intermediate layer from inside to outside. By controlling the connecting ring layer to be of a dense structure, the connecting strength and the compression resistance of the core layer and the shell layer can be improved, so that the particle structure of the ternary precursor material is more stable. At the same time, by controlling the average thickness of the center layer, the intermediate layer and the shell layer to be greater than the average thickness of the connecting ring layer, the thickness of the dense connecting ring layer is as small as possible, which can reduce the influence of the dense connecting ring layer on the lithium ion conductivity. Moreover, the ternary precursor provided in the present solution is a high-nickel product, and the internal particles of the ternary precursor grow uniformly without fault radiation, and the particle compression resistance and structural stability are high, which can significantly improve the energy density of the battery when used in the battery.

[0009] In a further preferred solution, the center layer is of a loose structure, and the intermediate layer and the shell layer are both of a dense structure; the average thickness of the connecting ring layer is less than 0.5 μm; the porosity of the connecting ring layer is less than or equal to 8%; the porosity of the center layer is less than or equal to 9%, the porosity of the intermediate layer is less than or equal to 8%, and the porosity of the shell layer is less than or equal to 6%.

[0010] More preferably, the porosity of the connecting ring layer is greater than or equal to 0.03% and less than or equal to 3.68%, and the average thickness of the connecting ring layer is less than or equal to 0.20 μm.

[0011] By controlling the intermediate layer, the connecting ring layer and the shell layer to be of a dense structure, the particles of the ternary precursor material grow without fault radiation and are tightly connected, which can enhance the consistency of the particles of the ternary precursor material, improve the connecting strength and the compression resistance of the inner and outer layers of the core-shell structure, and make the particle structure of the ternary precursor material more stable. Since the center layer is of a loose structure, it is beneficial to buffer the volume strain force in the battery cycle charging and discharging process when applied to the battery, reduce the resistance, and improve the battery cycle performance and safety performance.

[0012] And, in the porosity range of the connecting ring layer in the present scheme, the compactness inside the ternary precursor material particle can be improved, so that the ternary precursor material particle is uniform, the consistency inside the ternary precursor material is enhanced, thereby improving the compression resistance and structural strength of the ternary precursor material particle, while the influence on the lithium ion conductivity can be minimized, and when used in a battery, the battery cycle performance can be better.

[0013] Preferably, the porosity of the connecting ring layer is greater than or equal to 0.03% and less than or equal to 2.11%, the porosity of the center layer is 2.44%-7.96%, the porosity of the intermediate layer is less than or equal to 2.46%, and the porosity of the shell layer is less than or equal to 1.88%. At this time, the compression resistance and structural strength of the ternary precursor material particle can be further improved.

[0014] In a further preferred scheme, the average radius of the center layer is 0.48-0.72 μm; the average thickness of the intermediate layer is 0.72-1.08 μm; the average thickness of the shell layer is 2.72-4.08 μm; and the average thickness of the connecting ring layer is less than or equal to 0.20 μm.

[0015] The size thickness of the center layer of the ternary precursor needs to be strictly controlled. If the thickness is too large, the positive electrode material prepared after sintering of the ternary precursor will have a center hole that is too large, causing the material structure to collapse or crack during charging and discharging. If the thickness is too small, it is not conducive to buffering the stress generated by the volume change during the charging and discharging process. In the present scheme, the volume of the loose center layer inside the ternary precursor particle is moderate, which is conducive to buffering the volume strain force during the cyclic charging and discharging process, reducing the resistance, and improving the rate performance. Furthermore, by controlling the thickness of the intermediate layer and the shell layer, and controlling the thickness of the connecting ring layer to be as small as possible, the ternary precursor particle grows uniformly without faults, further enhancing the structural stability.

[0016] In a further preferred scheme, the average thickness of the connecting ring layer is 0.08-0.12 μm, and the particle size D50 of the ternary precursor is 8.0-12.0 μm. In the particle size range of the present scheme, the strength of the core-shell structure of the ternary precursor can be made as large as possible, while not affecting the lithium ion conductivity and conductivity performance of the ternary positive electrode material after the ternary precursor is made.

[0017] Preferably, the particle size D50 of the ternary precursor is 9.0-11.0 μm, and the structural strength and lithium ion conductivity of the ternary positive electrode material prepared at this time are better.

[0018] In a further preferred scheme, the primary particles constituting the intermediate layer and the connecting ring layer are needle-like or strip-like, the primary particles constituting the shell layer are plate-like or strip-like; the primary particles constituting the center layer are fine needles or strips; and the primary particles constituting the intermediate layer, the connecting ring layer and the shell layer grow radially.

[0019] The dense intermediate layer, the dense connecting ring layer and the dense shell layer of the present scheme are radially grown, and the particles are arranged in a tight and orderly manner along the radial direction of the core layer. When used as a positive electrode material of a battery, the radial structure can provide lithium ion deintercalation channels, improve the rate performance, and improve the lithium ion conductivity, thereby improving the battery performance.

[0020] Preferably, the size of the primary particles constituting the core layer and the intermediate layer is smaller than the size of the primary particles constituting the shell layer, that is, the size of the primary particles constituting the core layer is smaller than the size of the primary particles constituting the shell layer. This is conducive to the radial extension of the shell layer particles along the core layer particles, thereby facilitating the conduction of lithium ions.

[0021] Preferably, the length of the primary particles constituting the shell layer is 0.6-1.0 μm, the length of the primary particles constituting the core layer and the intermediate layer is 0.38-0.96 μm, and the length of the primary particles constituting the connecting ring layer is 0.32-0.92 μm. At this time, the diffusion resistance of lithium ions can be further reduced, which is conducive to the conduction of lithium ions.

[0022] In a further preferred scheme, in the X-ray diffraction spectrum of the ternary precursor, there is a half-peak width α of a 001 peak with a diffraction angle in the range of 19.2±1°, and there is a half-peak width β of a 101 peak with a diffraction angle in the range of 38.5±1°; wherein the half-peak width ratio β / α of the 101 peak to the 001 peak is 1.2-1.6:1, and the peak intensity ratio I of the 001 peak to the 101 peak is 1.0-1.8:1.

[0023] Preferably, the peak intensity ratio I of the 001 peak to the 101 peak is 1.2-1.6:1.

[0024] In the present scheme, the half-peak width of the 001 peak of the ternary precursor particle is small, the peak intensity value is high, the 001 crystal face of the particle grows first, the exposed area of the 001 crystal face is minimized, the particle has high crystallinity, the growth mode of the primary particle is affected, the particles are uniformly arranged and tightly and radially grown, and the ternary precursor formed has excellent structural stability. Moreover, the 001 peak intensity of the ternary precursor is greater than the 101 peak intensity, the crystallinity of the particle at the 001 peak is more advantageous, and when the ternary precursor is formed into a positive electrode material, it can exhibit excellent output characteristics, cycle performance and rate performance, thereby improving the battery capacity.

[0025] In a further preferred scheme, the specific surface area of the ternary precursor is 4-10 m 2 / g, the tap density is 2.0-2.3 g / cm 3 , and the particle size distribution (D90-D10) / D50≤0.70. When used in a battery, the ternary precursor has a large number of pores inside, can be in full contact with the electrolyte, and is conducive to improving the conductivity of the battery.

[0026] Preferably, the specific surface area of the ternary precursor is 6.5-8.5 m 2 / g, and the tap density is 2.0-2.2 g / cm 3 , (D90-D10) / D50≤0.67, at which point the battery conductivity can be further improved.

[0027] According to another aspect of the present application, a preparation method of a ternary precursor is provided, comprising the following steps:

[0028] The first reaction: a ternary mixed solution containing nickel, cobalt and manganese is added into a reaction kettle, and a pH regulator and a complexing agent are added to adjust the reaction solution to a first pH value and a first ammonia concentration, and a protective gas is introduced for the first reaction, and the seed particle size D50 after the first reaction is completed is 2.0-4.0 μm;

[0029] The second reaction: after the first reaction is completed, the reaction solution is adjusted to a second pH value and a second ammonia concentration for the second reaction, and the particle size D50 of the ternary precursor obtained after the second reaction is completed is 8-12 μm.

[0030] In the above technical solution of the present application, the first reaction is carried out under certain reaction conditions, the particles including a loose central layer and a dense intermediate layer are formed after the first reaction is completed, and then the reaction conditions are changed for the second reaction, and a dense connecting ring layer and a dense shell layer are formed on the outer layer of the central layer and the intermediate layer during the second reaction, until the ternary precursor material with a seamless and few-hole dense connecting ring layer in the inside, a dense intermediate layer and a dense shell layer is formed. The primary particles of the intermediate layer, the connecting ring layer and the shell layer of the ternary precursor material prepared by the method are orderly arranged and grow radially tightly, avoiding the existence of micro primary particles in the particle interior, reducing the porous gap of the particle arrangement, forming a dense structure of the orderly arranged few-hole seamless connecting ring layer, making the particle growth tightly connected without fault, and improving the particle compression resistance and structural strength.

[0031] In a further preferred scheme, the molar ratio of nickel, cobalt and manganese in the ternary mixed solution is x:y:z, wherein 0.75≤x<1.0, 0≤y<0.18, 0≤z<0.20, and x+y+z=1.

[0032] Preferably, the total concentration of nickel, cobalt and manganese metal ions in the ternary mixed solution is 90-130 g / L.

[0033] More preferably, doping is also possible, and the doping element M is at least one of Al, Ti, Zr, Mo, Cr, W, B, Mg, Ba, Nb and Sr. The doping element can be in the form of sulfate or chloride.

[0034] The ternary precursor prepared in this scheme is a high-nickel product, which has the advantages of good cycle performance, large energy density, stability and safety performance.

[0035] In a further preferred aspect, the first pH value is gradually decreased during the first reaction process, and the second pH value is gradually increased during the second reaction process.

[0036] The decrease of the pH during the first reaction process is conducive to the gradual formation of the loose center layer and the dense intermediate layer, and the increase of the pH during the second reaction process, in combination with the gradual increase of the second ammonia concentration during the second reaction process, is conducive to the rapid growth of the fine particles, the gradual formation of the dense structure of the ordered arrangement of the particles, the dense connection ring layer and the dense shell layer, the reduction of the inter-particle porosity, and the enhancement of the consistency and connectivity of the particles, thereby obtaining the seamless and less-porous connection ring layer of the ternary precursor material.

[0037] Preferably, the first pH value and the second pH value are both 10.0-12.5. At this time, it is conducive to the rapid growth of the particles in the center layer, the intermediate layer, the connection ring layer and the shell layer, so as to reduce the inter-particle porosity, improve the connection strength, and further improve the compression resistance and structural stability of the prepared ternary precursor.

[0038] Preferably, the second reaction end-point pH is 0.3-0.8 higher than the second reaction initial pH. By controlling the degree of increase of the pH, the particles can be grown in stages and in layers, and the consistency and connection strength of the particles can be improved.

[0039] Preferably, the pH regulator comprises one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate and soda ash. These alkaline substances can be used as the pH regulator to effectively regulate the pH, and the raw materials are widely available and simple to obtain.

[0040] Preferably, the pH regulator is a sodium hydroxide aqueous solution with a mass fraction of 25%-60%. The use of the sodium hydroxide aqueous solution with the concentration range in this aspect can effectively regulate the pH of the reaction solution, so as to facilitate the tight radial growth of the particles.

[0041] Preferably, the first ammonia concentration and the second ammonia concentration are both 3.5-8.5 g / L. By controlling the ammonia concentration, the particles can be further grown in a tight radial manner to form a dense structure and improve the stability.

[0042] Preferably, the end-point ammonia concentration value of the second ammonia concentration is 1.0-4.0 g / L higher than the initial ammonia concentration value of the second ammonia concentration. By controlling the degree of increase of the ammonia concentration, the particles can be grown uniformly, and the consistency and connection strength of the particles can be improved.

[0043] Preferably, the complexing agent comprises one or more of ammonia, EDTA, ethylenediamine, sodium citrate and urea. The use of these complexing agents can further accelerate the growth rate of the particles.

[0044] Preferably, the complexing agent is ammonia water with a mass fraction of 15%-45%. The ammonia water with the concentration range of the present solution can effectively control the ammonia concentration of the reaction solution, so as to facilitate the close radial growth of the particles.

[0045] In a further preferred solution, the reaction temperature in the first reaction and the second reaction is the same; the reaction temperature of the first reaction and the second reaction is kept unchanged, which is conducive to the uniform growth of the structure of each layer of the ternary precursor.

[0046] Preferably, the reaction temperature in the first reaction and the second reaction is 50-70℃.

[0047] In a further preferred solution, the reaction is carried out with stirring in the first reaction and the second reaction, and the stirring speed in the first reaction is kept unchanged, and the stirring speed in the second reaction is gradually reduced as the reaction proceeds.

[0048] Keeping the stirring speed unchanged in the first reaction is conducive to the formation of a loose central layer for buffering the volume strain force in the cyclic charging and discharging process; gradually reducing the stirring speed in the second reaction reduces the supersaturation of the reaction solution, which is conducive to the growth of the crystal on the interface, thereby quickly forming a dense connecting ring layer and a dense shell layer, and improving the compression resistance of the ternary precursor particles.

[0049] Preferably, the stirring speed in the first reaction is 200-240r / min, the stirring speed in the second reaction is 50-230r / min, and the stirring speed at the end of the second reaction is reduced to 50-110r / min, which is conducive to the growth of the central layer, the intermediate layer, the connecting ring layer and the shell layer.

[0050] In a further preferred solution, the particle size D50 of the crystal seed after the first reaction is 2.4-3.6μm, and the material after the first reaction includes the central layer and the intermediate layer. In the particle size range of the present solution, the central layer can present a loose structure, the size of the central hole of the ternary precursor can be controlled by controlling the appropriate size of the central layer, the structure with too large hole is prone to cracking and collapse, which is conducive to buffering the volume strain force of the inner and outer layers in the cyclic charging and discharging process, and a dense intermediate layer can be formed outside the loose central layer to improve the structural strength of the material.

[0051] In a further preferred solution, the particle size D50 of the ternary precursor after the second reaction is 9.0-11.0μm. After a certain period of the first reaction, the particle size reaches the above requirement, and the reaction is stopped to obtain a ternary precursor material with a seamless and few-hole connecting ring layer dense structure, which has good compression resistance and is conducive to improving the cycle life and charging and discharging efficiency of the battery.

[0052] Preferably, the ternary precursor particle size D50 after the second reaction is 9.5-10.5 μm, which is further beneficial to obtain a ternary precursor material with a compact structure and strong compression resistance.

[0053] According to another aspect of the present application, a battery positive electrode material is provided, which is prepared using the ternary precursor of any one of the above. The ternary precursor used in the present application has a seamless and low-pore connection ring layer compact structure, which specifically comprises a four-layer structure of a loose center layer, a compact intermediate layer, a seamless and low-pore compact connection ring layer, and a compact shell layer from inside to outside. The prepared battery positive electrode material is beneficial to buffer the volume strain force during the cycle charging and discharging process of the battery, reduce the resistance, enhance the compression resistance, and is beneficial to improve the cycle service life, the first charging and discharging efficiency, and the battery energy density.

[0054] According to another aspect of the present application, a battery positive electrode is provided, which comprises the battery positive electrode material described above. The battery positive electrode prepared by the battery positive electrode material described above is beneficial to improve the use effect of the battery.

[0055] According to another aspect of the present application, a lithium ion battery is provided, which comprises the battery positive electrode described above. The lithium ion battery assembled by the battery positive electrode described above has the advantages of small resistance, long service life, high battery energy density, etc.

[0056] According to another aspect of the present application, an electrical equipment is provided, which comprises the lithium ion battery described above. The lithium ion battery described above can be used to stably supply power to the corresponding electrical equipment, and ensure the continuous and stable operation of the equipment.

[0057] In summary, the ternary precursor and the preparation method thereof, and the positive electrode material provided by the present application at least have the following advantages

[0058] Advantages:

[0059] 1. The primary particles of the intermediate layer, the connection ring layer, and the shell layer of the ternary precursor particle are orderly arranged and grow radially, avoiding the disorderly connection of the fine primary particles inside the particle, and reducing the problem of insufficient compression resistance caused by the existence of porous gaps during particle arrangement.

[0060] 2. The ternary precursor particle retains the connection ring layer while making the connection ring layer as narrow as possible, forming a low-porosity ordered arrangement low-pore seamless compact structure, so that the particle growth is tightly connected without faults, the particle consistency of the material is enhanced, the connection force between the inner layer and the outer layer is enhanced, and the particle structure is more stable.

[0061] 3. During the cycle charging and discharging process, the positive electrode material prepared from the ternary precursor has high structural stability due to the high compactness of the inside and outside of the material particles, the side reactions of the electrolyte on the surface of the positive electrode active material can be reduced by using the compact structure, the gas production is effectively inhibited, and the cycle performance of the positive electrode active material is improved; the inside and outside of the particles are in a compact structure of uniform connection and radial growth, the particle growth has no fault, can provide an orderly and smooth lithium ion deintercalation channel and overcome the gap caused by the different volume changes of the core and the shell during the charging and discharging process, and the compact structure can enhance the particle structure strength, the particles are not easy to crack or collapse, the compression resistance of the particles is enhanced, which is further beneficial to improve the cycle service life and the first charge and discharge efficiency, thereby improving the energy density of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0063] Figure 1 is a structural schematic diagram of the ternary precursor provided by the embodiment of the present application;

[0064] Figure 2 is a sectional structural schematic diagram of the ternary precursor provided by the embodiment of the present application;

[0065] Figure 3 is a sectional view of the ternary precursor provided by the embodiment 1 of the present application;

[0066] Figure 4 is a sectional view of the ternary precursor provided by the embodiment 2 of the present application;

[0067] Figure 5 is a sectional view of the ternary precursor provided by the embodiment 3 of the present application;

[0068] Figure 6 is a sectional view of the ternary precursor provided by the embodiment 4 of the present application;

[0069] Figure 7 is a sectional view of the ternary precursor provided by the comparative example 1 of the present application;

[0070] Figure 8 is a sectional view of the ternary precursor provided by the comparative example 2 of the present application;

[0071] Figure 9 is a sectional view of the ternary precursor provided by the comparative example 3 of the present application;

[0072] Figure 10 is a cross-sectional view of the ternary precursor provided by Comparative Example 4 of the present application;

[0073] Figure 11 is an XRD pattern of the ternary precursor provided by Examples 1-4 of the present application;

[0074] Figures 1-2 In the center layer 100, the intermediate layer 200, the connecting ring layer 300, and the shell layer 400. DETAILED DESCRIPTION

[0075] It should be understood that the specific examples given herein are for explanatory purposes only and are not intended to be limiting.

[0076] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one ordinarily skilled in the art that the specific details need not be employed to practice the present application. In other instances, well-known steps or operations have not been described in detail in order to avoid obscuring the present application.

[0077] Reference Figures 1-2 As shown in the figure, the chemical general formula of the ternary precursor provided by the embodiments of the present application is Ni x Co y Mn z M a (OH)2, wherein 0.75≤x<1, 0≤y<0.18, 0≤z<0.20, 0≤a<0.1, x+y+z+a=1; M is at least one of Al, Ti, Zr, Mo, Cr, W, B, Mg, Ba, Nb and Sr; the ternary precursor comprises a core layer (including the center layer 100, the intermediate layer 200) from the inside to the outside, the connecting ring layer 300 and the shell layer 400, the center layer 100 is a loose structure, the intermediate layer 200, the connecting ring layer 300 and the shell layer 400 are all dense structures, and the average thickness of the center layer 100, the intermediate layer 200 and the shell layer 400 is all greater than the average thickness of the connecting ring layer 300.

[0078] The center layer with a loose porous structure is beneficial to buffer the volume strain force in the cyclic charge and discharge process, while the intermediate layer, the connecting ring layer and the shell layer are all dense structures with no gaps and few pores, so that the ternary precursor particle grows uniformly, the internal consistency is enhanced, and the particle compression resistance and structural strength can be improved.

[0079] In order to evaluate the characteristics of porosity, according to the SEM image of the prepared ternary precursor sample, the image analysis software (ImageJ) is used to directly calculate the pore area and cross-sectional area of each region, and the porosity of different regions is calculated by "porosity = pore area of each region / cross-sectional area of each region x 100%", and the porosity in this paper is characterized by this method.

[0080] In some alternative embodiments, the average thickness of the connecting ring layer is less than 0.5 μm; the porosity of the connecting ring layer is less than or equal to 8%; the porosity of the center layer is less than or equal to 9%, the porosity of the intermediate layer is less than or equal to 8%, and the porosity of the shell layer is less than or equal to 6%.

[0081] In some alternative embodiments, the porosity of the connecting ring layer is greater than 0.03% and less than or equal to 3.68%, and the average thickness of the connecting ring layer is less than or equal to 0.2 μm; and the porosity of the connecting ring layer is preferably greater than 0.03% and less than or equal to 2.11%, the porosity of the center layer is 2.44%-7.96%, the porosity of the intermediate layer is less than or equal to 2.46%, and the porosity of the shell layer is less than or equal to 1.88%. For example, the porosity of the connecting ring layer can be 0.03%, 0.10%, 0.30%, 0.50%, 0.70%, 0.80%, 1.00%, 1.20%, 1.50%, 1.80%, 2.00%, 2.20%, 2.50%, 2.80%, 3.00%, 3.20%, 3.33%, 3.68%, or any value between 0 and 3.68%; the average thickness of the connecting ring layer can be 0.01 μm, 0.05 μm, 0.08 μm, 0.1 μm, 0.12 μm, 0.15 μm, 0.20 μm, or any value less than or equal to 0.2 μm; the porosity of the center layer can be 2.44%, 3.44%, 4.44%, 5.44%, 6.44%, 7.96%, or any value between 2.44% and 7.96%; the porosity of the intermediate layer can be any value less than or equal to 2.46%; and the porosity of the shell layer can be any value less than or equal to 1.88%.

[0082] On the one hand, the loose center layer can be used in combination with the dense intermediate layer, the dense connecting ring layer, and the dense shell layer to improve the compression resistance and structural strength of the ternary precursor; on the other hand, the core-shell structure ternary precursor can also have good lithium ion conductivity, which is conducive to improving the battery performance.

[0083] In some alternative embodiments, the average radius of the center layer is 0.48-0.72 μm; the average thickness of the intermediate layer is 0.72-1.08 μm; the average thickness of the shell layer is 2.72-4.08 μm; and the average thickness of the connecting ring layer is less than or equal to 0.20 μm, and the average thickness of the connecting ring layer is preferably 0.08-0.12 μm. By adjusting the thickness of the center layer, the intermediate layer, the connecting ring layer, and the shell layer included in the ternary precursor, the volume strain force in the cyclic charge and discharge process can be buffered, the resistance can be reduced, and the cycle performance and safety performance can be improved.

[0084] For example, the average radius of the center layer can be 0.48 μm, 0.50 μm, 0.55 μm, 0.60 μm, 0.70 μm, 0.72 μm, or any value between 0.48 μm and 0.72 μm; the average thickness of the intermediate layer can be 0.72 μm, 0.75 μm, 0.8 μm, 0.85 μm, 0.90 μm, 0.95 μm, 1.0 μm, 1.05 μm, 1.08 μm, or any value between 0.72 μm and 1.08 μm; the average thickness of the shell layer can be 2.72 μm, 2.8 μm, 2.9 μm, 3.0 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4.0 μm, 4.05 μm, 4.08 μm, or any value between 2.72 μm and 4.08 μm; the average thickness of the connecting ring layer can be 0.01 μm, 0.05 μm, 0.08 μm, 0.1 μm, 0.12 μm, 0.15 μm, 0.20 μm, or any value less than or equal to 0.2 μm.

[0085] In some optional embodiments, the particle size D50 of the ternary precursor is 8.0-12.0 μm, and the particle size D50 of the ternary precursor is preferably 9.0-11.0 μm. For example, the particle size D50 of the ternary precursor can be 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11.0 μm, 11.5 μm, 12.0 μm, or any value between 8.0 μm and 12.0 μm.

[0086] In some optional embodiments, based on the growth mechanism of the particles, the loose center layer is irregularly spherical, and the surface is needle strip-shaped; the primary particles constituting the intermediate layer and the connecting ring layer are needle strip-shaped or strip-shaped, the primary particles constituting the shell layer are strip-shaped or strip-shaped, and the primary particles constituting the center layer are fine needles or strip-shaped; the primary particles constituting the intermediate layer, the connecting ring layer, and the shell layer grow radially along the center layer. Thus, the ternary precursor particles grow uniformly, without faults, radially, and closely and orderly, which is conducive to smoother lithium ion channels of the battery.

[0087] In some optional embodiments, the size of the primary particles constituting the center layer and the intermediate layer is smaller than the size of the primary particles constituting the shell layer, that is, the size of the primary particles of the core layer is smaller than the size of the primary particles of the shell layer, which is conducive to the radial, close, and orderly growth of the shell layer particles along the core layer particles.

[0088] In some alternative embodiments, the length of the primary particles constituting the shell layer is 0.6-1.0 μm, the length of the primary particles constituting the core layer and the intermediate layer is 0.38-0.96 μm; and the length of the primary particles constituting the connecting ring layer is 0.32-0.92 μm. For example, the length of the primary particles constituting the shell layer can be 0.6 μm, 0.70 μm, 0.80 μm, 0.90 μm, 1.0 μm, or any value between 0.6 μm and 1.0 μm; the length of the primary particles constituting the core layer can be 0.38 μm, 0.40 μm, 0.5 μm, 0.6 μm, 0.70 μm, 0.80 μm, 0.90 μm, 0.96 μm, or any value between 0.38 μm and 0.96 μm. The length of the primary particles constituting the connecting ring layer can be 0.32 μm, 0.40 μm, 0.50 μm, 0.60 μm, 0.70 μm, 0.80 μm, 0.90 μm, 0.92 μm, or any value between 0.32 μm and 0.92 μm.

[0089] In some alternative embodiments, by X-ray diffraction (XRD) analysis, in the X-ray diffraction pattern of the ternary precursor, there is a peak (001) with a diffraction angle 2θ = 19.2 ± 1° range, a half-peak width (FWHM) α, and a peak (101) with a 2θ = 38.5 ± 1° range, a half-peak width β; the ratio of the half-peak width β of the 101 peak to the half-peak width α of the 001 peak is 1.2-1.6:1, i.e. β / α is 1.2-1.6:1; the peak intensity ratio I(001 / 101) is 1.0-1.8:1, preferably 1.2-1.6:1.

[0090] For example, β / α can be 1.2, 1.3, 1.4, 1.5, 1.6, or any value between 1.2 and 1.6; the peak intensity ratio I(001 / 101) can be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or any value between 1.0 and 1.8.

[0091] Preferably, the closer the ratio of the peak intensity ratio I(001 / 101) to the half-peak width ratio β / α is to 1:1, the more compact the structure of the intermediate layer, the connecting ring layer and the shell layer included in the ternary precursor, and the higher the consistency of the ternary precursor material particles, thereby improving the connection strength and pressure resistance of the inner and outer layers of the core-shell structure.

[0092] In some alternative embodiments, the specific surface area BET of the ternary precursor is 4-10 m 2 / g, and the specific surface area BET is preferably 6.5-8.5 m 2 / g; the tap density TD is 2.0-2.3 g / cm 3 , and the tap density TD is preferably 2.0-2.2 g / cm 3; a particle size distribution (D90-D10) / D50 of 0.10 pm, 0.20 pm, 0.30 pm, 0.40 pm, 0.50 pm, 0.60 pm, 0.70 pm, or any value between 0 and 0.70 pm. 2 / g, 5 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, 9 m 2 / g, 10 m 2 / g, or 4 m 2 / g to 10 m 2 / g; the TD can be any value between 2.0 g / cm 3 , 2.05 g / cm 3 , 2.1 g / cm 3 , 2.15 g / cm 3 , 2.2 g / cm 3 , 2.25 g / cm 3 , 2.3 g / cm 3 , or any value between 2.0 g / cm 3 and 2.3 g / cm 3 ; the (D90-D10) / D50 can be 0.10 pm, 0.20 pm, 0.30 pm, 0.40 pm, 0.50 pm, 0.60 pm, 0.70 pm, or any value between 0 and 0.70 pm.

[0093] The embodiment of the present application also provides a preparation method of a ternary precursor, comprising the following steps: a first reaction: adding a ternary mixed solution containing nickel, cobalt and manganese into a reaction kettle, and adding a pH regulator and a complexing agent to adjust the reaction solution to be at a first pH value and a first ammonia concentration, and passing a protective gas to perform the first reaction, and the seed particle size D50 after the first reaction is completed is 2.0-4.0 pm; a second reaction: adjusting the reaction solution to be at a second pH value and a second ammonia concentration after the first reaction is completed to perform the second reaction, and the particle size D50 of the ternary precursor obtained after the second reaction is completed is 8-12 pm.

[0094] The particles between the inner core and shell of the ternary precursor material obtained by the preparation method can be effectively and uniformly connected, the particles at the connection ring layer are closely arranged and grown, the primary particles are uniformly connected, the particle growth connection strength is better, the consistency is better, and the radial growth is better.

[0095] In some alternative embodiments, the total concentration of nickel, cobalt and manganese metal ions in the ternary mixed solution is 90-130 g / L. For example, the total concentration of nickel, cobalt and manganese metal ions can be 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L, 130 g / L or any value between 90 g / L and 130 g / L.

[0096] In some alternative embodiments, the protective gas can be an inert gas or nitrogen to avoid impurities participating in the reaction.

[0097] In some alternative embodiments, the ternary mixed solution is a Ni, Co and Mn ternary solution (molar ratio Ni:Co:Mn = x:y:z, wherein 0.75≤x<1.0, 0≤y<0.18, 0≤z<0.20, and x+y+z = 1). The ternary precursor prepared by the present scheme is a high-nickel product, which has the advantages of good cycle performance, large energy density, and good stability and safety performance.

[0098] More preferably, the doping element M is at least one of Al, Ti, Zr, Mo, Cr, W, B, Mg, Ba, Nb and Sr. The doping element can be in the form of a sulfate or a chloride.

[0099] In some alternative embodiments, the first pH value is gradually decreased during the first reaction process; the second pH value is gradually increased during the second reaction process to maintain a high-pH reaction; and the second ammonia concentration is gradually increased during the second reaction process. This is conducive to the rapid growth of fine particles, the formation of a dense and less porous connecting ring layer with orderly arranged particles, and the close radial growth of primary particles, thereby enhancing the consistency and connectivity of the particles.

[0100] In some alternative embodiments, the first pH value and the second pH value are both 10.0-12.5. For example, the first pH value and the second pH value can both be 10.0, 10.5, 11.0, 11.5, 12.0, 12.5 or any value between 10.0 and 12.5.

[0101] In some alternative embodiments, the second reaction end-point pH is 0.3-0.8 higher than the second reaction initial pH. For example, the second reaction end-point pH can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or any value between 0.3 and 0.8 higher than the second reaction initial pH.

[0102] In some alternative embodiments, the pH regulator comprises one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate and soda ash.

[0103] In some alternative embodiments, the pH adjusting agent is a sodium hydroxide aqueous solution with a mass fraction of 25%-60%.

[0104] In some alternative embodiments, the first ammonia concentration and the second ammonia concentration are both 3.5-8.5 g / L. For example, the first ammonia concentration and the second ammonia concentration can both be 3.5 g / L, 4.0 g / L, 4.5 g / L, 5.0 g / L, 5.5 g / L, 6.0 g / L, 6.5 g / L, 7.0 g / L, 7.5 g / L, 8.0 g / L, 8.5 g / L, or any value between 3.5 g / L and 8.5 g / L.

[0105] In some alternative embodiments, the end point ammonia concentration value of the second ammonia concentration is 1.0-4.0 g / L higher than the initial ammonia concentration value of the second ammonia concentration, i.e., the second reaction end point ammonia concentration is 1.0-4.0 g / L higher than the second reaction initial ammonia concentration. For example, the second reaction end point ammonia concentration can be 1.0 g / L, 1.5 g / L, 2.0 g / L, 2.5 g / L, 3.0 g / L, 3.5 g / L, 4.0 g / L, or any value between 1.0 g / L and 4.0 g / L higher than the second reaction initial ammonia concentration.

[0106] In some alternative embodiments, the complexing agent comprises one or more of ammonia, EDTA, ethylenediamine, sodium citrate, and urea.

[0107] In some alternative embodiments, the complexing agent is ammonia water with a mass fraction of 15%-45%.

[0108] In some alternative embodiments, the reaction temperature during the first reaction and the second reaction is the same.

[0109] In some alternative embodiments, the reaction temperature during the first reaction and the second reaction is 50-70℃. For example, the reaction temperature during the first reaction and the second reaction can be 50℃, 55℃, 60℃, 65℃, 70℃, or any value between 50℃ and 70℃.

[0110] In some alternative embodiments, the first reaction and the second reaction are carried out while stirring, and the stirring speed during the first reaction is maintained constant, and the stirring speed during the second reaction is gradually reduced as the reaction proceeds.

[0111] In some alternative embodiments, the stirring speed of the first reaction is 200-240 r / min, the stirring speed of the second reaction is 50-230 r / min, and the stirring speed at the end of the second reaction is gradually reduced to 50-110 r / min in stages. For example, the stirring speed of the first reaction can be 200 r / min, 205 r / min, 210 r / min, 215 r / min, 220 r / min, 225 r / min, 230 r / min, 235 r / min, 240 r / min, or any value between 200 r / min and 240 r / min; the stirring speed of the second reaction can be 50 r / min, 70 r / min, 100 r / min, 120 r / min, 150 r / min, 170 r / min, 200 r / min, 230 r / min, or any value between 50 r / min and 230 r / min; and the stirring speed at the end of the second reaction can be reduced to 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min, 110 r / min, or any value between 50 r / min and 110 r / min.

[0112] In the above preparation method, the pH of the second reaction is gradually increased, and the pH at the end of the second reaction is 0.3-0.8 higher than the initial pH of the second reaction, and the ammonia concentration of the second reaction is gradually increased, and the ammonia concentration at the end of the second reaction is 1.0-4.0 g / L higher than the initial ammonia concentration of the second reaction. Thus, by increasing the pH of the system during the second reaction and increasing the ammonia concentration, the growth of fine particles at the beginning of the second reaction is affected, thereby forming a dense and less porous connecting ring layer with ordered particle arrangement, avoiding the formation of a gap porous connecting ring layer connected by fine particles, and facilitating the tight radioactive growth of primary particles, reducing the gap between the particles, and enhancing the consistency and connectivity of the particles. Moreover, the second reaction gradually reduces the stirring intensity and increases the pH, reducing the supersaturation of the solution, which is conducive to the growth of crystals on the interface and the stability of the crystal particles, thereby forming a dense structure to enhance the compression resistance and improve the structural stability.

[0113] In some alternative embodiments, the crystal seed particle size D50 after the first reaction is 2.0-4.0 μm, preferably 2.4-3.6 μm. For example, the crystal seed particle size D50 after the first reaction can be 2 μm, 2.4 μm, 2.5 μm, 3 μm, 3.5 μm, 3.6 μm, 4 μm, or any value between 2 μm and 4 μm.

[0114] In some optional embodiments, the particle size D50 of the ternary precursor after the second reaction is 8-12 μm, preferably 9-11 μm, and more preferably 9.5-10.5 μm. For example, the particle size D50 of the ternary precursor after the second reaction can be 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, or any value between 8 μm and 12 μm.

[0115] In some optional embodiments, the feeding flow rate of the ternary mixed solution during the first reaction and the second reaction is 1% / h-10% / h of the effective volume of the reactor. The feeding flow rate of 1% / h-10% / h means that the feeding flow rate of the ternary mixed solution is 1% / h-10% / h of the effective volume of the reactor, i.e., the volume of the ternary mixed solution added per hour accounts for 1% -10% of the effective volume of the reactor. By controlling the flow rate of the ternary metal during each reaction stage, the reaction rate can be accelerated, and the pH and ammonia concentration can be adjusted, which is beneficial to the formation of the ternary precursor with a loose center layer, a dense intermediate layer, a connecting ring layer, and a shell layer structure.

[0116] In some optional embodiments, the preparation method of the ternary precursor of the present application comprises the following steps:

[0117] 1. First reaction: by configuring ternary mixed solution of nickel, cobalt, and manganese metal raw materials in a certain proportion and concentration, liquid alkali (pH regulator), ammonia complexing agent, and inert gas nitrogen protection, controlling a certain reaction time, and reducing pH, a ternary precursor material including a center layer and an intermediate layer is formed.

[0118] 2. Second reaction: using the seed dry material obtained in the first reaction, the reaction conditions are adjusted, and the inert gas protection is used, the pH and ammonia concentration are adjusted, the reaction atmosphere affects the growth mode of the fine particles in the connecting ring layer with gaps in the internal particles, so that the gap porous connecting ring layer of the fine particle connection is optimized to become an ordered dense few-hole connecting ring layer. After a certain period of reaction, the required particle size is reached, and the reaction is stopped to obtain a ternary precursor material with a high-nickel seamless few-hole connecting ring layer dense structure.

[0119] Subsequently, the slurry obtained by the reaction is subjected to solid-liquid separation, aging, dewatering and drying, and screening, thereby obtaining the target product.

[0120] The preparation method is designed to optimize the connection between the fine particle core layer and the shell layer of the ternary precursor, so that the fine particle connection becomes uniform primary particle connection, the particles grow uniformly in a radial manner, the consistency is improved, and the connection between the inner and outer layers is enhanced. Secondly, the porous ring layer with gaps in the particles is optimized to form a dense structure of an ordered arrangement of a non-gap and a few-hole ring layer. The radial increase of the inner and outer layers is beneficial to provide lithium ion deintercalation channels, no fault channel, and more smoothness. Thirdly, the appropriate size of the loose center layer is controlled to control the size of the center hole, prevent the structure from cracking and collapsing due to the large hole, and be beneficial to buffer the volume strain force of the inner and outer layers in the cyclic charge and discharge process.

[0121] The application also provides a battery positive electrode material prepared by using the ternary precursor of any one of the above. For example, the battery positive electrode material can be prepared by mixing the ternary precursor with a lithium salt and then sintering.

[0122] The application also provides a battery positive electrode comprising the battery positive electrode material described above.

[0123] The application also provides a lithium ion battery comprising the battery positive electrode described above.

[0124] The application also provides an electrical equipment comprising the lithium ion battery described above. The electrical equipment can be powered by the lithium ion battery of the application or can charge the lithium ion battery of the application.

[0125] In order to make the purpose, technical scheme and beneficial effects of the application clearer, the application will be further described in detail below in combination with specific embodiments, but the specific embodiments described are only used to explain the application and do not limit the application.

[0126] Example 1

[0127] A positive electrode material precursor with a dense structure of a non-gap and a few-hole connection ring layer is prepared, and the chemical formula is Ni 0.80 Co 0.10 Mn 0.10 (OH)2.

[0128] 1. Select materials: use nickel sulfate, cobalt sulfate and manganese sulfate. The metal raw materials are mixed metal salt solutions with a total concentration of 110 g / L, and the molar ratio of nickel, cobalt and manganese is 0.80:0.10:0.10.

[0129] 2. First step: pure water as the base liquid in 1# reactor, add ammonia and liquid alkali to adjust ammonia concentration and pH, adjust the ammonia concentration of the system to 4.5 g / L, and the pH to 11.7; the reaction temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min. Under the protection of inert gas or nitrogen, the nickel-cobalt-manganese ternary metal mixed solution is fed into the 1# reactor, and liquid alkali and ammonia are added to maintain the reaction conditions for co-precipitation reaction. The flow rate of the ternary metal is 4% of the effective volume of the reactor per hour, and the pH is controlled to decrease during the reaction process to form a loose central layer of a certain size, and the final pH is adjusted to 11.0. When the particle size D50 reaches 3.04 μm, the feeding is stopped, and a ternary precursor material with a loose central layer and a dense intermediate layer structure is obtained.

[0130] 3. Second step: the dewatered dry base material of the first step is transferred to the 2# reactor, and pure water, ammonia and liquid alkali are added to adjust the ammonia concentration and pH value. The ammonia concentration of the system is controlled at 4.5 g / L, and the pH is 10.8. The temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min. Under the protection of inert gas or nitrogen, the ternary metal mixed solution is fed into the 2# reactor, and ammonia solution and sodium hydroxide solution are added to maintain the reaction conditions for co-precipitation reaction. The initial ternary metal flow rate is 2% of the effective volume of the reactor per hour, and the final ternary metal flow rate is 6% of the effective volume of the reactor per hour. The stirring speed gradually decreases during the reaction process, and the final speed is 100 r / min. The pH of the reaction system increases, and the ammonia concentration rises. The final pH is 11.2, and the final ammonia concentration is 6.0 g / L. When the particle size D50 of the slurry reaches 11.00 μm, the feeding is stopped.

[0131] Post-processing: After the reaction is stopped, the material is washed with an appropriate amount of dilute alkali and pure water, dried, sieved through a 400-mesh screen, and packaged and sealed. A ternary precursor with a seamless and few-hole connecting ring layer dense structure is obtained. Figure 3 A cross-sectional view of the ternary precursor obtained in Example 1.

[0132] Example 2

[0133] A positive electrode material precursor with a seamless and few-hole connecting ring layer dense structure is prepared, and the chemical formula is Ni 0.845 Co 0.10 Mn 0.05 Zr 0.005 (OH)2.

[0134] 1. Material selection: nickel sulfate, cobalt sulfate and manganese sulfate are used. The metal raw materials are prepared into a ternary mixed metal salt solution with a total concentration of 110 g / L, with the molar ratio of nickel, cobalt and manganese being 0.845:0.10:0.05; zirconium sulfate, sodium citrate and sulfuric acid are configured into a zirconium solution with a concentration of 1.71 g / L.

[0135] 2. First step: pure water, ammonia and liquid alkali are used to adjust the ammonia concentration and pH in the 1# reactor, the ammonia concentration of the system is adjusted to 4.5 g / L, and the pH is adjusted to 11.7; the reaction temperature is raised to 60°C, the stirring speed is controlled at 220 r / min, under the protection of inert gas or nitrogen, the nickel-cobalt-manganese ternary metal mixed solution and the zirconium solution are fed into the 1# reactor, and the liquid alkali and ammonia water used to maintain the reaction conditions are supplemented to carry out the coprecipitation reaction. The flow rate of the ternary metal is 4% of the effective volume of the reactor per hour, the flow rate of the zirconium solution is 2.0% per hour, the pH is adjusted downward during the reaction process, a loose central layer of a certain size is formed, and the final pH is adjusted to 11.0. When the particle size D50 reaches 2.96 μm, the feeding is stopped, and a ternary precursor material with a loose central layer and a dense intermediate layer structure is obtained.

[0136] 3. Second step: the dewatered dry base material of the slurry of the first step is transferred into the 2# reactor, pure water is supplemented, ammonia and liquid alkali are added, the ammonia concentration and pH value are adjusted, the ammonia concentration of the system is controlled at 4.5 g / L, the pH is 10.8, the temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min. Under the protection of inert gas or nitrogen, the ternary metal mixed solution and the zirconium solution are fed into the 2# reactor, and the ammonia solution and sodium hydroxide solution used to maintain the reaction conditions are supplemented to carry out the coprecipitation reaction; the flow rate of the ternary metal is increased in steps, the initial flow rate of the ternary metal is 2% of the effective volume of the reactor per hour, the initial flow rate of the zirconium solution is 1% per hour, the final flow rate of the ternary metal is 6.5% of the effective volume of the reactor per hour, the final flow rate of the zirconium solution is 3.25% per hour, the stirring speed is gradually reduced during the reaction process, and the final speed is 100 r / min; the pH of the reaction system is raised, and the ammonia concentration is increased, the final pH is 11.3, and the final ammonia concentration is 6.5 g / L. When the particle size D50 of the slurry reaches 10.06 μm, the feeding is stopped.

[0137] Post-treatment: after the reaction is stopped, the material is washed with an appropriate amount of dilute alkali and pure water, dried, sieved through a 400-mesh sieve, and packaged and sealed. Thus a ternary precursor with a seamless and few-hole connecting ring layer dense structure is obtained. Figure 4 The cross-sectional view of the ternary precursor obtained in Example 2.

[0138] Example 3

[0139] A positive electrode material precursor with a seamless and few-hole connecting ring layer dense structure is prepared, and the chemical formula is Ni 0.90 Co 0.05 Mn 0.05 (OH)2.

[0140] 1. Selection of materials: nickel sulfate, cobalt sulfate and manganese sulfate are used. The metal raw materials are mixed into a ternary mixed metal salt solution with a total concentration of 110 g / L, with a molar ratio of nickel, cobalt and manganese of 0.90:0.05:0.05.

[0141] 2. First step: pure water, ammonia and liquid alkali are added to 1# reactor to adjust the ammonia concentration and pH, the ammonia concentration of the system is adjusted to 4.5 g / L, and the pH is 11.7; the reaction temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min; under the protection of inert gas or nitrogen, the nickel-cobalt-manganese ternary metal mixed solution is fed into 1# reactor, and liquid alkali and ammonia are added to maintain the reaction conditions for co-precipitation reaction. The flow rate of the ternary metal is 4% of the effective volume of the reactor per hour, and the pH is adjusted downward during the reaction process to form a loose central layer with a certain size, and the final pH is adjusted to 11.0. When the particle size D50 reaches 2.54 μm, the feeding is stopped, and a ternary precursor material with a loose central layer and a dense intermediate layer structure is obtained.

[0142] 3. Second step: the dewatered dry base material of the first step is transferred to 2# reactor, and pure water, ammonia and liquid alkali are added to adjust the ammonia concentration and pH, the ammonia concentration of the system is 4.5 g / L, and the pH is 10.8; the temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min; under the protection of inert gas or nitrogen, the ternary metal mixed solution is fed into 2# reactor, and ammonia solution and sodium hydroxide solution are added to maintain the reaction conditions for co-precipitation reaction; the flow rate of the ternary metal increases in steps, the initial flow rate of the ternary metal is 2% of the effective volume of the reactor per hour, and the final flow rate of the ternary metal is 7% of the effective volume of the reactor per hour; the stirring speed gradually decreases during the reaction process, and the final speed is 100 r / min; the pH of the reaction system is raised, and the ammonia concentration is increased, and the final pH is 11.4 and the final ammonia concentration is 7.0 g / L. When the particle size D50 of the slurry reaches 10.27 μm, the feeding is stopped.

[0143] Post-processing: after the reaction is stopped, the material is washed with appropriate amount of dilute alkali and pure water, dried, sieved through 400 mesh screen, and packaged and sealed. A ternary precursor material with a seamless and few-hole connecting ring layer dense structure is obtained. Figure 5 The cross-sectional view of the ternary precursor obtained in Example 3.

[0144] Example 4

[0145] A positive electrode material precursor with a seamless and few-hole connecting ring layer dense structure is prepared, and the chemical formula is Ni 0.95 Co 0.02 Mn 0.03 (OH)2.

[0146] 1. Selection of materials: nickel sulfate, cobalt sulfate and manganese sulfate are used. The metal raw materials are mixed into a ternary mixed metal salt solution with a total concentration of 110 g / L in a molar ratio of nickel, cobalt and manganese of 0.95:0.02:0.03.

[0147] 2. First step: pure water is used as the base solution in a 1# reactor, ammonia water and liquid alkali are added to adjust the ammonia concentration and pH, the ammonia concentration of the system is adjusted to 4.5 g / L, and the pH is 11.7; the reaction temperature is raised to 60°C, the stirring speed is controlled at 220 r / min, under the protection of inert gas or nitrogen, the nickel-cobalt-manganese ternary metal mixed solution is introduced into the 1# reactor, and liquid alkali and ammonia water are added to maintain the reaction conditions for co-precipitation reaction. The flow rate of the ternary metal is 4% of the effective volume of the reactor per hour, the pH is adjusted downward during the reaction process, a loose central layer of a certain size is formed, and the final pH is adjusted to 11.0. When the particle size D50 reaches 2.94 μm, the feeding is stopped. A ternary precursor material with a loose central layer and a dense intermediate layer structure is obtained.

[0148] 3. Second step: the dewatered dry base material from the first step is transferred to a 2# reactor, pure water, ammonia water and liquid alkali are added to adjust the ammonia concentration and pH, the ammonia concentration of the system is 4.5 g / L, and the pH is 10.8, the temperature is raised to 60°C, the stirring speed is controlled at 220 r / min, under the protection of inert gas argon, the ternary metal mixed solution is introduced into the 2# reactor, and ammonia water solution and sodium hydroxide solution are added to maintain the reaction conditions for co-precipitation reaction; the flow rate of the ternary metal is increased in steps, the initial flow rate of the ternary metal is 2% of the effective volume of the reactor per hour, and the final flow rate of the ternary metal is 7.5% of the effective volume of the reactor per hour, the stirring speed is gradually reduced during the reaction process, and the final speed is 100 r / min; the pH of the reaction system is increased, and the ammonia concentration is increased, the final pH is 11.5, and the final ammonia concentration is 7.5 g / L. When the particle size D50 of the slurry reaches 9.87 μm, the feeding is stopped.

[0149] Post-treatment: after the reaction is stopped, the material is washed with an appropriate amount of dilute alkali and pure water, dried, sieved through a 400 mesh sieve, packaged and sealed. A ternary precursor material with a seamless and few-pore ring layer structure is obtained. Figure 6 The cross-sectional view of the ternary precursor obtained in Example 4.

[0150] Comparative Example 1

[0151] A positive electrode material precursor with a gap-porous ring layer structure connected by fine particles is prepared, and the chemical formula is Ni 0.80 Co 0.10 Mn 0.10 (OH)2.

[0152] 1. Selection of materials: using nickel sulfate, cobalt sulfate and manganese sulfate. The metal raw materials are mixed into a ternary mixed metal salt solution with a total concentration of 110 g / L, with a molar ratio of nickel, cobalt and manganese of 0.80:0.10:0.10.

[0153] 2. First step: pure water, ammonia and liquid alkali are added to 1# reactor to adjust the ammonia concentration and pH, the ammonia concentration of the system is adjusted to 4.5 g / L, and the pH is 11.7; the reaction temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min; the nickel-cobalt-manganese ternary metal mixed solution is introduced into 1# reactor, and liquid alkali and ammonia are added to maintain the reaction conditions for co-precipitation reaction. The ternary metal flow rate is 4.0% of the effective volume of the reactor per hour, the final pH is adjusted to 11.0, and when the particle size D50 reaches 3.42 μm, the feeding is stopped, and a ternary precursor material with a loose central layer and a tight intermediate layer structure is obtained.

[0154] 3. Second step: the dewatered dry material from the first step is transferred to 2# reactor, and pure water, ammonia and liquid alkali are added to adjust the ammonia concentration and pH, the ammonia concentration of the system is 4.5 g / L, the initial pH is 10.8, the temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min; the ternary metal mixed solution is introduced into 2# reactor, and ammonia solution and sodium hydroxide solution are added to maintain the reaction conditions for co-precipitation reaction; the initial ternary metal flow rate is 2% of the effective volume of the reactor per hour, and the final ternary metal flow rate is 6% of the effective volume of the reactor per hour; the stirring speed is gradually reduced during the reaction process, and the final stirring speed is 100 r / min; the pH of the system decreases during the reaction process, and the final pH is 10.7; the ammonia concentration remains unchanged; when the particle size D50 of the slurry reaches 9.02 μm, the feeding is stopped.

[0155] Post-processing: after the reaction is stopped, the material is washed with appropriate amount of dilute alkali and pure water, dried, sieved through 400 mesh screen, and packaged and sealed. A ternary precursor with a loose porous gap structure connecting ring layer is obtained. Figure 7 The cross-sectional view of the ternary precursor obtained in Comparative Example 1.

[0156] Comparative Example 2

[0157] A positive electrode material precursor with a porous gap ring layer structure is prepared, and the chemical formula is Ni 0.845 Co 0.10 Mn 0.05 Zr 0.005 (OH)2.

[0158] 1. Selection of materials: nickel sulfate, cobalt sulfate and manganese sulfate are used. The metal raw materials are mixed into a ternary mixed metal salt solution with a total concentration of 110 g / L in a molar ratio of nickel, cobalt and manganese of 0.845:0.10:0.05. Zirconium sulfate, sodium citrate and sulfuric acid are configured into a zirconium solution of 1.71 g / L.

[0159] 2 First step: pure water, ammonia and liquid alkali are added to 1# reactor to adjust the ammonia concentration and pH, the ammonia concentration of the system is adjusted to 4.5 g / L, and the pH is 11.7; the reaction temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min; the nickel-cobalt-manganese ternary metal mixed solution and the zirconium solution are fed into 1# reactor, and liquid alkali and ammonia are added to maintain the reaction conditions for co-precipitation reaction. The flow rate of the ternary metal is 4.0% of the effective volume of the reactor per hour, and the flow rate of the zirconium solution is 2.0% per hour. When the end point pH is adjusted to 11.0 and the particle size D50 reaches 3.8 μm, the feeding is stopped, and a ternary precursor material with a loose central layer and a tight intermediate layer structure is obtained.

[0160] 3. Second step: the dewatered dry base material of the first step is transferred to 2# reactor, and pure water, ammonia and liquid alkali are added to adjust the ammonia concentration and pH value, the ammonia concentration of the system is 4.5 g / L, the pH value at the beginning is 10.8, the temperature is raised to 60°C, and the stirring speed is controlled at 220 r / min. The ternary metal mixed solution and the zirconium solution are fed into 2# reactor, and ammonia solution and sodium hydroxide solution are added to maintain the reaction conditions for co-precipitation reaction. The flow rate of the ternary metal increases in stages, the initial flow rate of the ternary metal is 2% of the effective volume of the reactor per hour, the initial flow rate of the zirconium solution is 1.0% per hour, the final flow rate of the ternary metal is 6% of the effective volume of the reactor per hour, and the final flow rate of the zirconium solution is 3.0% per hour. The stirring speed gradually decreases during the reaction process, and the final speed is 100 r / min. The pH of the system decreases during the reaction process, and the final pH is 10.6. The ammonia concentration of the system decreases, and the final ammonia concentration is 4.0 g / L. When the particle size D50 of the slurry reaches 10.00 μm, the feeding is stopped.

[0161] Post-processing: after the reaction is stopped, the material is washed with appropriate amount of dilute alkali and pure water, dried, sieved through a 400 mesh screen, packaged and sealed. A ternary precursor with a loose and porous gap connecting ring layer is obtained. Figure 8 The cross-sectional view of the ternary precursor obtained in Comparative Example 2.

[0162] Comparative Example 3

[0163] A positive electrode material precursor with a tight and disordered arrangement inside and a gap porous ring structure outside is prepared, and the chemical formula is Ni 0.80 Co 0.10 Mn 0.10 (OH)2.

[0164] 1. Select materials: use nickel sulfate, cobalt sulfate and manganese sulfate. The molar ratio of nickel, cobalt and manganese in the raw metal is 0.80:0.10:0.10, and a ternary mixed metal salt solution with a total concentration of 110 g / L is prepared.

[0165] 2. First step: pure water, ammonia and liquid alkali are added to 1# reactor to adjust the ammonia concentration and pH, the ammonia concentration of the system is adjusted to 5.0 g / L, and the pH is 11.8; the reaction temperature is raised to 60℃, the stirring speed is controlled at 210 r / min, the nickel-cobalt-manganese ternary metal mixed solution is introduced into 1# reactor, and liquid alkali and ammonia are supplemented to maintain the reaction conditions for co-precipitation reaction. The flow rate of the ternary metal is maintained at 5% of the effective volume of the reactor per hour, and the process is continuously overflowed with mother liquor to control the particle size D50 in the range of 2.59-2.69 μm, and the internal compact and disordered arrangement of the ternary precursor material is obtained.

[0166] 3. Second step: the dewatered dry base material of the first step is transferred to 2# reactor, and pure water, ammonia and liquid alkali are added to adjust the ammonia concentration and pH, the ammonia concentration of the system is 5 g / L, and the pH is 10.8, the temperature is raised to 60℃, the stirring speed is controlled at 200 r / min, the ternary metal mixed solution is introduced into 2# reactor, and ammonia solution and sodium hydroxide solution are supplemented to maintain the reaction conditions for co-precipitation reaction; the flow rate of the ternary metal is increased in steps, the initial flow rate of the ternary metal is 2% of the effective volume of the reactor per hour, and the final flow rate of the ternary metal is 6% of the effective volume of the reactor per hour, the pH of the system decreases during the reaction process, and the final pH is 10.6; the ammonia concentration of the system decreases, and the final ammonia concentration is 4.0 g / L; when the particle size D50 reaches 10.00 μm, the feeding is stopped.

[0167] Post-processing: after the reaction is stopped, the material is washed with appropriate amount of dilute alkali and pure water, dried, sieved through 400 mesh screen, packaged and sealed. A ternary precursor with internal compact and disordered arrangement, external radiation and porous ring structure is obtained. Figure 9 The cross-sectional view of the ternary precursor obtained in Comparative Example 3.

[0168] Comparative Example 4

[0169] A positive electrode material precursor with no radial and no porous ring structure is prepared, and the chemical formula is Ni 0.80 Co 0.10 Mn 0.10 (OH)2.

[0170] 1. Select materials: use nickel sulfate, cobalt sulfate and manganese sulfate. The molar ratio of nickel, cobalt and manganese in the raw metal is 0.80:0.10:0.10, and a ternary mixed metal salt solution with a total concentration of 110 g / L is prepared.

[0171] 2. First step: pure water, ammonia water and liquid alkali are added to the first reactor to adjust the ammonia concentration and pH, the ammonia concentration of the system is adjusted to 5.0 g / L, and the pH is adjusted to 11.1; the reaction temperature is raised to 60°C, the stirring speed is controlled at 220 r / min, the nickel-cobalt-manganese ternary metal mixed solution is introduced into the first reactor, and liquid alkali and ammonia water are supplemented to maintain the reaction conditions for co-precipitation reaction. The flow rate of the ternary metal is maintained at 4% of the effective volume of the reactor per hour during the reaction process, and the overflow mother liquor is maintained throughout the process to keep the particle size D50 in the range of 2.0-4.0 μm, and a ternary precursor material with fine crack tight structure is obtained.

[0172] 3. Second step: 6 m 3 of slurry from the first step storage tank is transferred to the second reactor, ammonia water and liquid alkali are added to adjust the ammonia concentration and pH, the ammonia concentration of the system is adjusted to 5.0 g / L, and the pH is adjusted to 10.8; the reaction temperature is raised to 60°C, the stirring speed is controlled at 200 r / min, the nickel-cobalt-manganese ternary metal mixed solution is introduced into the second reactor under inert gas or nitrogen protection, and liquid alkali and ammonia water are supplemented to maintain the reaction conditions for co-precipitation reaction. During the reaction process, the flow rate of the ternary metal is maintained at 5% of the effective volume of the reactor per hour, the flow rate of the ternary metal is kept constant, the stirring speed is kept constant, and the pH and ammonia concentration are kept constant. When the slurry particle size D50 reaches 9.96 μm, the feeding is stopped, and a ternary precursor with no radial and no porous ring layer tight structure is obtained. Figure 10 The cross-sectional view of the ternary precursor obtained in Comparative Example 4.

[0173] Table 1 shows the structure characteristics of each layer of the ternary precursor in each example and each comparative example.

[0174]

[0175] Table 2 shows the primary particle length of each layer of the ternary precursor in each example and each comparative example.

[0176]

[0177] Table 3 shows the porosity and average thickness of each layer of the ternary precursor in each example and comparative example.

[0178]

[0179] Table 4 shows the physicochemical properties of the ternary precursor in each example and comparative example.

[0180]

[0181] According to the above Figures 2-11And Table 1-4 can be known that the interface between the core and the shell of the core-shell ternary precursor positive electrode material in Comparative Examples 1, 2 and 3 has a porous gap ring layer connected by needle-shaped micro-particles, the core has a radial structure, and the shell has a radial structure, and Comparative Example 4 has no connection ring inside and is compact without a radial structure. The strip-shaped primary particles between the core-shell layers in the ternary precursors in Examples 1-4 are uniformly and compactly connected without a fault, grow compactly and radially, the particles are highly consistent, and the porosity of the connection ring layer in Examples 1-4 is less than that of the connection ring layer in Comparative Examples. The compact structure of the seamless and low-porosity connection ring layer in Examples 1-4 enhances the compression resistance and is more stable.

[0182] It can be known from Table 4 that the TD of the ternary precursors in Examples 1-4 is 0.07-0.19 g / cm 3 higher than that of the ternary precursors in Comparative Examples 1-4.

[0183] Performance test

[0184] 2000 g of the ternary precursors prepared in Examples and Comparative Examples and LiOH·H2O were uniformly mixed by a high-speed mixer in a molar ratio of 1:1.03, sintered in an air atmosphere by using a box furnace, the sintering temperature was 780°C, the high-temperature sintering time was 12 h, and after cooling to room temperature, the sintered product was crushed and sieved to obtain a nickel-cobalt-manganese ternary positive electrode material.

[0185] The electrochemical performance was tested by using a button half-electricity: the above positive electrode material, conductive carbon black and binder PVDF (polyvinylidene fluoride) were mixed in a ratio of 8:1:1 to form a slurry, which was coated on an aluminum foil to form a positive electrode sheet, a metal lithium sheet was used as a negative electrode sheet, a 1 mol / L LiPF6 / EC:DMC (volume ratio 1:1) electrolyte was used, and a battery shell, a positive and negative electrode sheet, a separator, a spring and a gasket were assembled into a button battery in a vacuum glove box. The electrochemical performance was tested by using a blue electricity test system.

[0186] At room temperature, 1C cycle test was performed for 50 weeks under the condition of 3.0-4.3V, and the electrochemical performance is shown in Table 2.

[0187] Table 5 shows the electrochemical performance index of the ternary positive electrode material substance.

[0188]

[0189]

[0190] It can be known from the electrochemical performance in Table 5 that the compactness of the positive electrode material in Examples 1-4 is improved by 0.11 g / cm 3 -0.24 g / cm compared with Comparative Examples 1, 2 and 3.3 The particle compression resistance is enhanced; the cycle 50 week retention rate of the electrochemical performance of the positive electrode material in Examples 1-4 is improved by 2.80%-4.25% while the specific capacity is maintained, the first charge-discharge capacity is improved by 2.4 mAh / g-5.1 mAh / g, the first charge-discharge efficiency is improved by 1.33%-2.45%, which is beneficial to improve the energy density of the battery. Compared with the inner non-connected ring layer without radial compact structure material in Comparative Example 4, the cycle 50 week retention rate of the electrochemical performance of the positive electrode material in Examples 1-4 is improved by 6.61%-7.04%, the first charge-discharge capacity is improved by 24.4 mAh / g-25.3 mAh / g, and the first charge-discharge efficiency is improved by 8.57%-9.41%. It can be seen that the electrochemical performance of the radial compact structure ternary precursor material in Examples 1-4 is obviously improved compared with the electrochemical performance of the comparative example, and the ternary positive electrode material of the present application has better excellent performance.

[0191] The technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by the present description, as long as such a combination does not contradict.

[0192] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A ternary precursor, characterized in that, The ternary precursor is nickel-cobalt-manganese hydroxide; The ternary precursor comprises, from the inside out, a core layer, a connecting layer, and a shell layer; The connecting ring has a dense structure with a porosity of 0.03%-3.68% and an average thickness of less than 0.5μm; The core layer includes a central layer and an intermediate layer from the inside out, and the average thickness of the central layer, the intermediate layer and the shell layer is greater than the average thickness of the connecting ring layer; The central layer has a loose structure, while the intermediate layer and the shell layer both have a dense structure. The porosity of the central layer is less than or equal to 9%, the porosity of the intermediate layer is less than or equal to 8%, and the porosity of the shell layer is less than or equal to 6%. The average thickness of the intermediate layer is 0.72-1.08 μm; the average thickness of the shell layer is 2.72-4.08 μm.

2. The ternary precursor according to claim 1, characterized in that, The general chemical formula of the ternary precursor is Ni x Co y Mn z M a (OH)2, wherein 0.75≤x<1, 0≤y<0.18, 0≤z<0.20, 0≤a<0.1, x+y+z+a=1; wherein M is at least one of Al, Ti, Zr, Mo, Cr, W, B, Mg, Ba, Nb and Sr.

3. The ternary precursor according to claim 1 or 2, characterized in that, The porosity of the central layer is 2.44%-7.96%, the porosity of the intermediate layer is less than or equal to 2.46%, and the porosity of the shell layer is less than or equal to 1.88%; the average radius of the central layer is 0.48-0.72 μm. The average thickness of the connecting ring is less than or equal to 0.2 μm; The average particle size of the ternary precursor is 8-12 μm.

4. The ternary precursor according to claim 1 or 2, characterized in that, The primary particles constituting the intermediate layer and the connecting ring layer are needle-shaped or strip-shaped, the primary particles constituting the shell layer are plate-shaped or strip-shaped, and the primary particles constituting the central layer are fine needle-shaped or strip-shaped. The primary particles constituting the intermediate layer, the connecting ring layer, and the shell layer grow radially.

5. The ternary precursor according to claim 4, characterized in that, The size of the primary particles constituting the central layer and the intermediate layer is smaller than the size of the primary particles constituting the shell layer.

6. The ternary precursor according to claim 5, characterized in that, The primary particles constituting the shell layer have a length of 0.6-1.0 μm, the primary particles constituting the central layer and the intermediate layer have a length of 0.38-0.96 μm, and the primary particles constituting the connecting ring layer have a length of 0.32-0.92 μm.

7. The ternary precursor according to claim 1, 2, 5 or 6, characterized in that, In the X-ray diffraction pattern of the ternary precursor, there is a 001 peak with a diffraction angle in the range of 19.2±1° and a half-maximum width of α, and a 101 peak with a diffraction angle in the range of 38.5±1° and a half-maximum width of β. The half-width ratio β / α of the 101 peak and the 001 peak is 1.2-1.6:1, and the peak intensity ratio I of the 001 peak and the 101 peak is 1.0-1.8:

1.

8. The ternary precursor according to claim 7, characterized in that, The peak intensity ratio I between the 001 peak and the 101 peak is 1.2-1.6:

1.

9. The ternary precursor according to claim 1, 2, 5, 6 or 8, characterized in that, The specific surface area of ​​the ternary precursor is 4-10m². 2 / g, tap density is 2.0-2.3g / cm³ 3 Particle size distribution (D90-D10) / D50 ≤ 0.

70.

10. The ternary precursor according to claim 9, characterized in that, The specific surface area of ​​the ternary precursor is 6.5-8.5 m². 2 / g, tap density is 2.0-2.2g / cm³ 3 .

11. A method for preparing a ternary precursor as described in any one of claims 1-10, characterized in that, Includes the following steps: First reaction: A ternary mixed solution containing nickel, cobalt and manganese is added to the reaction vessel, and a pH adjuster and a complexing agent are added to adjust the reaction solution to a first pH value and a first ammonia concentration. A protective gas is introduced to carry out the first reaction. The seed particle size D50 after the first reaction is completed is 2.0-4.0 μm. Second reaction: After the first reaction is completed, the reaction solution is adjusted to a second pH value and a second ammonia concentration to carry out the second reaction. After the second reaction is completed, the particle size D50 of the ternary precursor is 8-12 μm.

12. The method for preparing the ternary precursor according to claim 11, characterized in that, The total concentration of nickel, cobalt, and manganese metal ions in the ternary mixed solution is 90-130 g / L.

13. The method for preparing the ternary precursor according to claim 11 or 12, characterized in that, In the first reaction, the first pH value is gradually decreased; in the second reaction, the second pH value is gradually increased; and in the second reaction, the second ammonia concentration is gradually increased.

14. The method for preparing the ternary precursor according to claim 13, characterized in that, Both the first pH value and the second pH value are 10.0-12.

5.

15. The method for preparing the ternary precursor according to claim 13, characterized in that, The final pH of the second reaction is 0.3-0.8 higher than the initial pH of the second reaction.

16. The method for preparing the ternary precursor according to claim 13, characterized in that, The concentrations of the first ammonia and the second ammonia are both 3.5-8.5 g / L.

17. The method for preparing the ternary precursor according to claim 13, characterized in that, The final ammonia concentration value of the second ammonia concentration is 1.0-4.0 g / L higher than the initial ammonia concentration value of the second ammonia concentration.

18. The method for preparing the ternary precursor according to claim 11 or 12, characterized in that, The stirring speed remains constant during the first reaction process, while the stirring speed gradually decreases during the second reaction process.

19. The method for preparing the ternary precursor according to claim 18, characterized in that, The stirring speed for the first reaction is 200-240 r / min, the stirring speed for the second reaction is 50-230 r / min, and the stirring speed is reduced to 50-110 r / min at the end of the second reaction.

20. A battery positive electrode material, characterized in that, It is prepared by sintering a mixture of the ternary precursor described in any one of claims 1 to 10 and a lithium salt.

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