Positive electrode material precursor, preparation method therefor, and use thereof

Abstract

A positive electrode material precursor, a preparation method therefor, and a use thereof. The positive electrode material precursor has a core-shell structure, comprising an inner core, an outer shell, and an intermediate layer located between the inner core and the outer shell. The inner core is formed by stacking a first sheet material, the first sheet material being formed by stacking multiple layers of primary sheet material; the intermediate layer is formed by stacking the primary sheet material; the outer shell is formed by stacking a second sheet material, the second sheet material being formed by stacking multiple layers of the primary sheet material. The number of primary sheet material layers in the second sheet material is less than the number of primary sheet material layers in the first sheet material. The positive electrode material precursor has a specific surface area of ​​10m2 / g-20m2 / g. The precursor has a unique structure with a compact inner core and outer shell and a loose intermediate layer, resulting in a large specific surface area. When used to prepare positive electrode materials, said precursor has high tap density and sintering yield, and can achieve excellent cycle stability and rate performance in batteries.

Description

Positive electrode material precursor, preparation method and application thereof

[0001] The present application claims priority to the Chinese patent application No. 202410894673.X, filed on July 4, 2024, and entitled "Positive electrode material precursor, preparation method and application thereof", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a positive electrode material precursor, a preparation method and application thereof. BACKGROUND

[0003] The performance of the positive electrode material is largely determined by the precursor. Since the precursor inside the particles is compact, the specific surface area of the positive electrode material corresponding to the compact precursor is small, which results in a small contact area between the positive electrode material and the electrolyte, thereby leading to a low rate performance of the battery. Although the specific surface area of the precursor can be increased by refining the primary particles, the refined primary particles are easy to break, and the debris generated by the breaking will be over-fired in the sintering process. In addition, the sintered positive electrode material is easy to break due to the low strength of the broken primary particles in the sintering process. The over-fired debris and the broken positive electrode material are easy to react with the electrolyte in the battery charging and discharging process, thereby reducing the electrical performance of the battery and posing a safety hazard.

[0004] SUMMARY

[0005] Therefore, it is necessary to provide a positive electrode material precursor, a preparation method and application thereof in view of the above problems. The precursor has a unique structure with a compact inner core and shell and a loose intermediate layer, has a large specific surface area, has high tap density and sintering yield when used for preparing a positive electrode material, and can realize excellent cycle stability and rate performance when the positive electrode material prepared therefrom is used in a battery.

[0006] A positive electrode material precursor, the positive electrode material precursor has a core-shell structure, comprising an inner core, a shell and an intermediate layer between the inner core and the shell;

[0007] The inner core is composed of a first sheet material, and the first sheet material is composed of a plurality of layers of primary sheet materials.

[0008] The intermediate layer is composed of a primary sheet material.

[0009] The shell is composed of a second sheet material, and the second sheet material is composed of a plurality of layers of primary sheet materials. The number of layers of the primary sheet materials in the second sheet material is less than the number of layers of the primary sheet materials in the first sheet material.

[0010] The specific surface area of the positive electrode material precursor is 10 m 2 / g-20 m2 / g.

[0011] In one of the embodiments, the number of layers of the primary sheet-like material in the first sheet-like material is greater than or equal to 5.

[0012] In one of the embodiments, the porosity of the inner core is less than the porosity of the outer shell, and the porosity of the outer shell is less than the porosity of the intermediate layer.

[0013] In one of the embodiments, the positive electrode material precursor satisfies at least one of the following conditions:

[0014] (1) the porosity of the positive electrode material precursor is 5%-10%;

[0015] (2) the porosity of the inner core is less than or equal to 2%;

[0016] (3) the porosity of the intermediate layer is 10%-12%;

[0017] (4) the porosity of the outer shell is 5%-8%.

[0018] In one of the embodiments, the positive electrode material precursor further satisfies at least one of the following conditions:

[0019] (1) the average thickness of the first sheet-like material is 130 nm-170 nm;

[0020] (2) the average thickness of the primary sheet-like material in the intermediate layer is less than or equal to 60 nm;

[0021] (3) the average thickness of the second sheet-like material is 70 nm-120 nm;

[0022] (4) the diameter of the inner core is 3 μm-7 μm;

[0023] (5) the thickness of the intermediate layer is 1 μm-2.5 μm;

[0024] (6) the thickness of the outer shell is 1 μm-4 μm;

[0025] (7) the diameter of the positive electrode material precursor is 7 μm-20 μm.

[0026] In one of the embodiments, in the X-ray diffraction pattern of the positive electrode material precursor, at least one of the following conditions is satisfied:

[0027] (1) the diffraction peak intensity of the (001) crystal plane is greater than or equal to 7000 cps, and the average grain size of the positive electrode material precursor along the direction perpendicular to the (001) crystal plane is greater than or equal to 10 nm;

[0028] (2), the diffraction peak intensity of (101) crystal surface is greater than or equal to 7000cps, and the average grain size of the positive electrode material precursor along the direction perpendicular to (101) crystal surface is greater than or equal to 10nm;

[0029] (3), the diffraction peak intensity of (100) crystal surface is greater than or equal to 4000cps, and the average grain size of the positive electrode material precursor along the direction perpendicular to (100) crystal surface is greater than or equal to 25nm.

[0030] In one embodiment, the chemical formula of the positive electrode material precursor is Ni x Co y Mn z (OH)2, wherein 0.5≤x≤0.95, 0≤y≤0.25, 0≤z≤0.25, x+y+z=1 and y, z are not zero at the same time.

[0031] A preparation method of the positive electrode material precursor as described above, comprising the following steps:

[0032] Mixing ammonia solution and sodium hydroxide solution to prepare a first reaction bottom solution and a second reaction bottom solution respectively, the ammonia concentration of the first reaction bottom solution and the second reaction bottom solution is c1, c2 respectively, c1

[0033] In the first reaction bottom solution, ammonia solution, sodium hydroxide solution and mixed salt solution are passed through in parallel to carry out the first reaction to prepare the inner core, wherein the flow rate of the mixed salt solution is 200L / h-400L / h, the ammonia concentration of the reaction solution during the first reaction is c1, and the reaction temperature is T1;

[0034] Mixing the inner core with the second reaction bottom solution, and passing ammonia solution, sodium hydroxide solution and mixed salt solution through in parallel to carry out the second reaction to prepare the intermediate, wherein the flow rate of the mixed salt solution is 1000L / h-1500L / h, the ammonia concentration of the reaction solution during the second reaction is c2, and the reaction temperature is T2;

[0035] Continue to pass ammonia solution, sodium hydroxide solution and mixed salt solution through in parallel to carry out the third reaction to prepare the positive electrode material precursor, wherein the flow rate of the mixed salt solution is 400L / h-800L / h, the ammonia concentration of the reaction solution during the third reaction is c1, and the reaction temperature is T3, and T2

[0036] In one embodiment, the first reaction, the second reaction and the third reaction satisfy at least one of the following conditions:

[0037] (1), the pH of the first reaction bottom solution is greater than the pH of the second reaction bottom solution;

[0038] (2) the pH of the reaction solution in the first reaction is greater than the pH of the reaction solution in the second reaction;

[0039] (3) the pH of the reaction solution at the end of the second reaction is equal to the pH of the reaction solution in the third reaction;

[0040] (4) the stirring speed in the first reaction is greater than the stirring speed in the second reaction;

[0041] (5) the stirring speed in the second reaction is greater than the stirring speed in the third reaction.

[0042] In one embodiment, the preparation method satisfies at least one of the following conditions:

[0043] (1) the pH of the first reaction solution is 12.1-12.3, and c1 is 1 g / L-4 g / L;

[0044] (2) the pH of the second reaction solution is 11.1-11.3, and c2 is 5 g / L-8 g / L;

[0045] (3) in the first reaction step, T1 is 55-60°C, the stirring speed is 400-500 r / min, the pH of the reaction solution is 11.5-12.3, and the diameter of the inner core is 3-7 μm;

[0046] (4) in the second reaction step, T2 is 40-50°C, the stirring speed is 200-350 r / min, the pH of the reaction solution at the end of the reaction is 10.5-10.6, and the diameter of the intermediate is 5-12 μm;

[0047] (5) in the third reaction step, T3 is 50-55°C, the stirring speed is 180-200 r / min, the pH of the reaction solution is 10.5-10.6, and the diameter of the positive material precursor is 7-20 μm.

[0048] In one embodiment, the preparation method further satisfies at least one of the following conditions:

[0049] (1) the concentration of the ammonia solution is 5-15 mol / L;

[0050] (2) the concentration of the sodium hydroxide solution is 9-12 mol / L;

[0051] (3) the concentration of the mixed salt solution is 1.5-2.5 mol / L;

[0052] (4) In the first reaction step, the pH of the reaction solution is maintained at 12.1-12.3 for 1-4 hours, and then reduced to 11.5-11.8 for 6-8 hours.

[0053] (5) In the step of mixing the core with the second reaction substrate, the solid content is 10g / L-100g / L;

[0054] (6) The preparation method is carried out in a protective atmosphere with an oxygen content of less than or equal to 0.1% and a pressure of 0.2MPa-0.7MPa.

[0055] A cathode material is obtained from a cathode material precursor as described above.

[0056] A positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on the surface of the positive current collector, wherein the positive electrode material layer includes the positive electrode material as described above.

[0057] A battery comprising a positive electrode as described above.

[0058] The cathode material precursor described in this application has three different spatial structures composed of primary sheet-like materials from the inside out, giving the precursor a unique structure with a compact core and outer shell and a loose middle layer, while also achieving a specific surface area as high as 10m². 2 / g-20m 2 / g, on the one hand, can not only effectively avoid the problem of primary sheet materials peeling off into crystal nuclei and causing overburning under external force, but also facilitate the diffusion of ions during the preparation of cathode materials, thereby improving the sintering yield; on the other hand, it can increase the tap density of the precursor, which is beneficial to improving the structural strength of the cathode material, buffering the volume change of the cathode material during charging and discharging, and increasing the contact area between the cathode material and the electrolyte, thereby improving the cycle stability and rate performance of the battery. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0060] Figure 1 is a cross-sectional electron microscope image of the cathode material precursor prepared in Example 1, wherein region a is the core, region b is the intermediate layer, and region c is the outer shell.

[0061] Figure 2 is a surface electron microscope image of the core obtained in Example 1;

[0062] Figure 3 is a surface electron microscope image of the intermediate prepared in Example 1;

[0063] Figure 4 is a surface electron microscope image of the positive electrode material precursor prepared in Example 1;

[0064] Figure 5 is an X-ray diffraction pattern of the positive electrode material precursor prepared in Example 1;

[0065] Figure 6 is a cross-section electron microscope image of the positive electrode material precursor prepared in Comparative Example 1;

[0066] Figure 7 is a surface electron microscope image of the positive electrode material precursor prepared in Comparative Example 1. DETAILED DESCRIPTION

[0067] For the purpose of promoting an understanding of the present application, the present application will be described in greater detail below. It should be understood, however, that the present application can be embodied in many different forms and should not be construed as limited to the embodiments or examples set forth herein. Rather, these embodiments or examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0068] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments or examples only and is not intended to be limiting of the present application.

[0069] The present application provides a positive electrode material precursor, which has a core-shell structure comprising an inner core, an outer shell and an intermediate layer between the inner core and the outer shell.

[0070] The inner core is composed of a first sheet material accumulation, and the first sheet material is composed of a plurality of layers of primary sheet material; the intermediate layer is composed of a primary sheet material accumulation; the outer shell is composed of a second sheet material accumulation, and the second sheet material is composed of a plurality of layers of primary sheet material, and the number of layers of primary sheet material in the second sheet material is less than the number of layers of primary sheet material in the first sheet material; the specific surface area of the positive electrode material precursor is 10 m 2 / g-20 m 2 / g.

[0071] The positive electrode material precursor described in the present application has three different spatial structures composed of primary sheet material from the inside to the outside, which makes the precursor have a unique structure of a compact inner core and outer shell and a loose intermediate layer, and the specific surface area is as high as 10 m 2 / g-20 m 2On the one hand, not only can the problem of peeling off into crystal nucleus and overburning of the primary flaky material under the action of external force be effectively avoided, but also the ion diffusion in the preparation process of the positive electrode material is facilitated, thereby improving the sintering yield; on the other hand, the tap density of the precursor can be improved, which is beneficial to improving the structural strength of the positive electrode material, buffering the volume change of the positive electrode material in the charging and discharging process, and at the same time, the contact area of the positive electrode material and the electrolyte can be improved, thereby improving the cycle stability and rate performance of the battery.

[0072] Preferably, the specific surface area of the positive electrode material precursor is 10 m 2 / g-15 m 2 / g.

[0073] In an embodiment, the number of layers of the primary flaky material in the first flaky material is greater than or equal to 5, and preferably the number of layers is 6-10, and it can be understood that the number of layers of the primary flaky material in the second flaky material is less than 5, and further preferably, the average thickness of the first flaky material is 130 nm-170 nm, and more preferably 140 nm-160 nm, and / or the average thickness of the second flaky material is 70 nm-120 nm, and more preferably 80 nm-110 nm, and / or the average thickness of the primary flaky material in the intermediate layer is less than or equal to 60 nm, and more preferably 40 nm-60 nm, by adjusting the number of layers of the primary flaky material in the first flaky material and the second flaky material, the thickness size of the primary flaky material in the first flaky material, the second flaky material and the intermediate layer, the structure of the precursor can be further accurately controlled, the structural stability is improved, and at the same time, the high specific surface area of the precursor is ensured.

[0074] In an embodiment, the porosity of the core is less than the porosity of the shell, and the porosity of the shell is less than the porosity of the intermediate layer, and preferably, the porosity of the positive electrode material precursor is 5%-10%, and more preferably 5%-8%, and further preferably, the porosity of the core is less than or equal to 2%, and more preferably 1.5%-2%, and / or the porosity of the intermediate layer is 10%-12%, and more preferably 10.5%-11.5%, and / or the porosity of the shell is 5%-8%, and more preferably 5.5%-7.5%, by adjusting the porosity between the precursor and the core, the intermediate layer and the shell, the unique structure of the compact core and the loose intermediate layer can be further optimized, the sintering yield of the positive electrode material is improved, and at the same time, the cycle stability and rate performance of the battery are improved.

[0075] In an embodiment, the diameter of the positive electrode material precursor is 7-20 μm, more preferably 10-15 μm, preferably, the diameter of the core is 3-7 μm, more preferably 4-6 μm, and / or the thickness of the intermediate layer is 1-2.5 μm, more preferably 1.5-2 μm, and / or the thickness of the shell is 1-4 μm, more preferably 1-2.5 μm. By adjusting the size of the precursor and the thickness of the core, the intermediate layer and the shell, the structure of the precursor can be further optimized, and the activity and stability of the precursor can be improved.

[0076] In an embodiment, in the X-ray diffraction pattern of the positive electrode material precursor, the diffraction peak intensity of the (001) crystal plane is greater than or equal to 7000 cps, preferably 7500-9000 cps; and the average grain size of the positive electrode material precursor along the direction perpendicular to the (001) crystal plane is greater than or equal to 10 nm, preferably 10-15 nm.

[0077] In an embodiment, in the X-ray diffraction pattern of the positive electrode material precursor, the diffraction peak intensity of the (101) crystal plane is greater than or equal to 7000 cps, preferably 7000-8500 cps; and the average grain size of the positive electrode material precursor along the direction perpendicular to the (101) crystal plane is greater than or equal to 10 nm, preferably 10-15 nm.

[0078] In an embodiment, in the X-ray diffraction pattern of the positive electrode material precursor, the diffraction peak intensity of the (100) crystal plane is greater than or equal to 4000 cps, preferably 4000-6000 cps; and the average grain size of the positive electrode material precursor along the direction perpendicular to the (100) crystal plane is greater than or equal to 25 nm, preferably 30-40 nm.

[0079] By adjusting the diffraction peak intensity of the (001) crystal plane, the (101) crystal plane and the (100) crystal plane and the corresponding grain size, the structural stability can be improved.

[0080] In an embodiment, the chemical formula of the positive electrode material precursor is Ni x Co y Mn z (OH)2, wherein 0.5≤x≤0.95, 0≤y≤0.25, 0≤z≤0.25, x+y+z=1 and y and z are not simultaneously 0, preferably 0.8≤x≤0.94, 0.03≤y≤0.1, 0.03≤z≤0.1. It can be understood that the positive electrode material precursor can also contain doping elements, which are not limited in the present application.

[0081] The application provides a preparation method of the positive electrode material precursor, comprising the following steps:

[0082] S1, preparing ammonia water solution, sodium hydroxide solution and mixed salt solution;

[0083] S2, mixing the ammonia water solution and the sodium hydroxide solution to prepare a first reaction bottom solution and a second reaction bottom solution respectively, the ammonia concentration of the first reaction bottom solution and the second reaction bottom solution is c1 and c2 respectively, c1 < c2;

[0084] S3, flowing the ammonia water solution, the sodium hydroxide solution and the mixed salt solution into the first reaction bottom solution to perform a first reaction to prepare a core, wherein the flow rate of the mixed salt solution is 200 L / h-400 L / h, the ammonia concentration of the reaction solution in the first reaction process is c1, and the reaction temperature is T1;

[0085] S4, mixing the core with the second reaction bottom solution, and flowing the ammonia water solution, the sodium hydroxide solution and the mixed salt solution into the core to perform a second reaction to prepare an intermediate, wherein the flow rate of the mixed salt solution is 1000 L / h-1500 L / h, the ammonia concentration of the reaction solution in the second reaction process is c2, and the reaction temperature is T2;

[0086] S5, continuously flowing the ammonia water solution, the sodium hydroxide solution and the mixed salt solution into the intermediate to perform a third reaction to prepare the positive electrode material precursor, wherein the flow rate of the mixed salt solution is 400 L / h-800 L / h, the ammonia concentration of the reaction solution in the third reaction process is c1, and the reaction temperature is T3, and T2 < T3 < T1.

[0087] In step S1, the concentration of the ammonia water solution is 5 mol / L-15 mol / L, preferably 7 mol / L-12 mol / L; and / or, the concentration of the sodium hydroxide solution is 9 mol / L-12 mol / L, preferably 10 mol / L-11 mol / L; and / or, the concentration of the mixed salt solution is 1.5 mol / L-2.5 mol / L, preferably 1.8 mol / L-2 mol / L.

[0088] It can be understood that the mixed salt solution at least contains Ni, Co and Mn, and can also contain other doping elements, and the application does not make any limitation in this regard.

[0089] In step S2, preferably, the pH of the first reaction bottom solution is greater than the pH of the second reaction bottom solution, and further preferably, the pH of the first reaction bottom solution is 12.1-12.3, and c1 is 1 g / L-4 g / L; and / or, the pH of the second reaction bottom solution is 11.1-11.3, and c2 is 5 g / L-8 g / L, by adjusting the ammonia concentration and the pH of the reaction bottom solution, the stable reaction can be accurately controlled.

[0090] In an embodiment, under a protective atmosphere, with an oxygen content less than 0.1%, a pressure of 0.2-0.7 MPa, the ammonia solution and the sodium hydroxide solution are mixed to form a first reaction bottom liquid at a temperature of 50-60°C and a stirring speed of 450-500 r / min.

[0091] In an embodiment, under a protective atmosphere, with an oxygen content less than 0.1%, a pressure of 0.2-0.7 MPa, the ammonia solution and the sodium hydroxide solution are mixed to form a second reaction bottom liquid at a temperature of 40-50°C and a stirring speed of 350-400 r / min.

[0092] In steps S3-S5, by synergistically regulating the ammonia concentration, the flow rate of the mixed salt solution, and the reaction temperature of the third-order reaction, the primary sheet-like material generated by the reaction forms three different spatial structures from the inside to the outside, so that the precursor prepared by the third-order reaction has a unique structure with a compact inner core and outer shell and a loose intermediate layer, and the precursor has a high specific surface area of 10-20 m 2 / g. 2 / g. In addition, the preparation method provided by the application has the advantages of simple reaction process, easy control, high repeatability, and wide application prospect.

[0093] In an embodiment, the pH of the reaction liquid in the first reaction process is greater than the pH of the reaction liquid in the second reaction process, and / or the pH of the reaction liquid at the end of the second reaction is equal to the pH of the reaction liquid in the third reaction process. By regulating the pH relationship in the three-stage reaction, the morphology and size of the product can be accurately controlled, thereby further optimizing the spatial structure of the precursor.

[0094] In an embodiment, the stirring speed in the first reaction is greater than the stirring speed in the second reaction, and / or the stirring speed in the second reaction is greater than the stirring speed in the third reaction. By regulating the stirring speed relationship in the three-stage reaction, the morphology and size of the product can be accurately controlled, thereby further optimizing the spatial structure of the precursor.

[0095] Preferably, in the first reaction step, T1 is 55-60°C, the stirring speed is 400-500 r / min, and the pH of the reaction liquid is 11.5-12.3. By regulating the temperature, pH, and stirring speed of the first reaction, the formation of the multi-layer primary sheet-like material structure in the inner core can be further accurately controlled, and the diameter of the inner core can be ensured to be 3-7 μm.

[0096] Further preferably, in the first reaction step, the pH of the reaction solution is first maintained at 12.1-12.3 for 1-4 hours, and then reduced to 11.5-11.8 for 6-8 hours; the stirring speed is first maintained at 450-500 r / min for 5-10 hours, and then reduced to 400-450 r / min, which is conducive to further accurate control of the formation of the multi-layer primary sheet material structure of the inner core.

[0097] It should be noted that the present application does not limit the order of preparation of the first reaction and the second reaction bottom solution. The second reaction bottom solution can be prepared first and then the first reaction is performed, or the first reaction can be performed first and then the second reaction bottom solution is prepared.

[0098] It can be understood that when the first reaction is performed first and then the second reaction bottom solution is prepared, the second reaction bottom solution can be prepared first and then the second reaction is performed, or the inner core can be directly mixed with the ammonia solution and the sodium hydroxide solution to form a mixed dispersion liquid that can be subjected to the second reaction. Since the inner core has little effect on the ammonia concentration and the pH of the reaction, the pH of the reaction solution at the beginning of the second reaction step is the pH of the second reaction bottom solution.

[0099] As a preference, in the second reaction step, T2 is 40-50°C, the stirring speed is 200-350 r / min, and the pH of the reaction solution at the end of the reaction is 10.5-10.6. Further preferably, the pH of the reaction solution is reduced to 10.5-10.6 within 20 hours, and the solid content is 10-100 g / L. By adjusting the temperature, pH, stirring speed, and solid content of the second reaction, it is conducive to further accurate control of the formation of the unique structure of the inner core being compact and the surface layer being loose, and to ensure that the diameter of the intermediate reaches 5-12 μm.

[0100] It should be noted that during the second reaction, the stirring speed can be accurately adjusted according to the particle size of the reaction product, which is not limited by the present application.

[0101] As a preference, in the third reaction step, T3 is 50-55°C, the stirring speed is 180-200 r / min, and the pH of the reaction solution is 10.5-10.6. Specifically, the temperature is increased from T2 to T3 within 10 hours, and the ammonia concentration is reduced from c2 to c1 within 10 hours, which is conducive to further accurate control of the formation of the unique structure of the positive material precursor, in which the inner core and the outer shell are compact and the intermediate layer is loose, and to ensure that the diameter of the positive material precursor reaches 7-20 μm.

[0102] In an embodiment, the above reaction processes are all carried out in a protective atmosphere to ensure that the oxygen content is less than or equal to 0.1%, and the pressure is preferably 0.2-0.7 MPa.

[0103] In an embodiment, the product prepared in the third reaction is further subjected to aging, washing, pressure filtration, drying, sieving, demagnetization, packaging and the like, and finally a positive electrode material precursor product is obtained.

[0104] The application provides a positive electrode material prepared from the positive electrode material precursor as described above. The positive electrode material has a stable crystal structure, a high yield, and is less likely to cause grain cracking and the like during charging and discharging, which is beneficial to improving the cycle stability and rate capability of the battery.

[0105] It should be noted that the application does not limit the preparation method of the positive electrode material, and the positive electrode material can be prepared by using a conventional sintering process.

[0106] The application also provides a positive electrode sheet, which comprises a positive electrode current collector and a positive electrode material layer arranged on the surface of the positive electrode current collector, and the positive electrode material layer comprises the positive electrode material described in the application.

[0107] In an embodiment, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. The composite current collector comprises a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material on a polymer material base material. Alternatively, the metal material comprises at least one of, but is not limited to, aluminum, aluminum gold, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. Alternatively, the polymer material base material comprises at least one of, but is not limited to, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0108] In an embodiment, the positive electrode material layer mainly comprises the positive electrode material described in the application, a binder and a conductive agent. Alternatively, the conductive agent comprises at least one of, but is not limited to, carbon black, carbon nanotubes, graphene and carbon nanofibers, wherein the carbon black comprises superconducting carbon, acetylene black or ketjen black.

[0109] It should be noted that the application does not limit the preparation method of the positive electrode sheet, and the positive electrode sheet can be prepared by using a conventional process. For example, the positive electrode material, the conductive agent, the binder and any other components are dispersed in a solvent to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after the processes such as drying and cold pressing, the positive electrode sheet is obtained. Alternatively, the solvent comprises, but is not limited to, N-methyl pyrrolidone.

[0110] The application provides a battery comprising the positive plate as described above. It can be understood that the battery is mainly composed of the positive plate, a negative plate, a separator and an electrolyte, wherein the negative plate, the separator and the electrolyte can adopt any conventional commercially available negative plate or negative material, separator and electrolyte, and the application does not limit this; the battery includes but is not limited to a lithium ion battery, a sodium ion battery and the like.

[0111] Hereinafter, the positive material precursor, the preparation method and the application thereof will be further described through the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the application, and should not be regarded as limiting the scope of the application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are adopted. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be obtained on the market.

[0112] Example 1

[0113] (1) An ammonia solution with a concentration of 10 mol / L, a sodium hydroxide solution with a concentration of 10 mol / L and a mixed salt solution with a concentration of 2 mol / L are prepared, wherein the mixed salt solution is prepared by dissolving soluble nickel sulfate, soluble cobalt sulfate and soluble manganese sulfate in water according to a molar ratio of Ni:Co:Mn=92:4:4.

[0114] (2) Under a nitrogen atmosphere, the oxygen content in the reaction kettle is controlled to be 0.1%, and the pressure is 0.2 MPa. The ammonia solution and the sodium hydroxide solution are introduced into the reaction kettle and stirred at 460 r / min to form a first reaction bottom liquid at 55°C, wherein the ammonia concentration in the first reaction bottom liquid is 3.5 g / L, and the pH is 12.3.

[0115] (3) Under the condition of 55°C, the mixed salt solution, the sodium hydroxide solution and the ammonia solution are introduced into the reaction kettle containing the first reaction bottom liquid in parallel. The pH of the reaction solution is maintained at 12.3 for 3 h, and then decreased to 11.6 for 8 h. At the same time, the stirring speed of 460 r / min is maintained for 8 h, and then decreased to 420 r / min. The ammonia concentration is maintained at 3.5 g / L during the reaction process. The flow rate of the mixed salt solution is 300 L / h. Until the reaction product grows to the target particle size of 5 μm, the reaction is stopped.

[0116] (4) The reaction product is transferred to another reaction kettle, and the ammonia solution and the sodium hydroxide solution are introduced and stirred at 350 r / min under the condition of 46°C, so that the solid content is 60 g / L, the pH is 11.1, and the ammonia concentration is 6 g / L.

[0117] (5) under the condition of 46℃, the mixed salt solution, the sodium hydroxide solution and the ammonia solution are continuously fed into the reactor, the pH is controlled to decrease from 11.1 to 10.5 in 20h, the ammonia concentration is kept at 6g / L, the flow rate of the mixed salt solution is 1200L / h, when the particle size of the reaction product is about 5.5±0.5μm, the stirring speed is 300r / min; when the particle size of the reaction product is about 6.5±0.5μm, the stirring speed is 250r / min; when the particle size of the reaction product is about 7.5±0.5μm, the stirring speed is 200r / min, until the reaction product grows to the target particle size of 8μm.

[0118] (6) the mixed salt solution, the sodium hydroxide solution and the ammonia solution are continuously fed into the reactor, the pH is controlled to keep at 10.5, the temperature is increased from 46℃ to 50℃ in 10h, the ammonia concentration is decreased from 6g / L to 3.5g / L in 10h, the flow rate of the mixed salt solution is 500L / h, the stirring speed is 180r / min, until the reaction product grows to the target particle size of 10μm, the reaction is ended.

[0119] (7) the reaction product is subjected to the processes of aging, washing, pressure filtration, drying, sieving, demagnetization and packaging to obtain the positive electrode material precursor, the chemical formula of the precursor is Ni 0.92 Co 0.04 Mn 0.04 (OH)2.

[0120] Example 2

[0121] Example 2 is different from Example 1 in that the solid content in step (4) is 40g / L, and the flow rate of the mixed salt solution in step (5) is 1300L / h.

[0122] Example 3

[0123] Example 3 is different from Example 1 in that the target particle size in step (3) is 7μm, the solid content in step (4) is 20g / L, and the flow rate of the mixed salt solution in step (5) is 1500L / h.

[0124] Example 4

[0125] (1) the ammonia solution with a concentration of 5mol / L, the sodium hydroxide solution with a concentration of 9mol / L and the mixed salt solution with a concentration of 1.5mol / L are prepared, wherein the mixed salt solution is prepared by dissolving soluble nickel sulfate, soluble cobalt sulfate and soluble manganese sulfate in water according to the molar ratio of Ni:Co:Mn=90:5:5.

[0126] (2) Under the atmosphere of nitrogen, the oxygen content in the reactor is controlled to be 0.05%, and the pressure is controlled to be 0.3 MPa. Ammonia solution and sodium hydroxide solution are introduced into the reactor and stirred at 480 r / min to form a first reaction bottom solution. The ammonia concentration in the first reaction bottom solution is 3.8 g / L, and the pH is 12.2 at 58°C.

[0127] (3) At 58°C, the mixed salt solution, sodium hydroxide solution and ammonia solution are introduced into the reactor containing the first reaction bottom solution. The pH of the reaction solution is maintained at 12.2 for 2 h, and then decreased to 11.7 for 6 h. The stirring speed is maintained at 480 r / min for 6 h, and then decreased to 430 r / min. The ammonia concentration is maintained at 3.8 g / L. The flow rate of the mixed salt solution is 400 L / h. The reaction is stopped when the target particle size of the reaction product reaches 4.5 μm.

[0128] (4) The reaction product is transferred to another reactor. Ammonia solution and sodium hydroxide solution are introduced into the reactor and stirred at 300 r / min to form a second reaction bottom solution. The solid content of the second reaction bottom solution is 30 g / L, the pH is 11.2, and the ammonia concentration is 7 g / L at 45°C.

[0129] (5) At 45°C, the mixed salt solution, sodium hydroxide solution and ammonia solution are introduced into the reactor. The pH is decreased from 11.2 to 10.6 in 20 h. The ammonia concentration is maintained at 7 g / L. The flow rate of the mixed salt solution is 1300 L / h. When the particle size of the reaction product is about 5.5±0.5 μm, the stirring speed is 280 r / min. When the particle size of the reaction product is about 6.5±0.5 μm, the stirring speed is 240 r / min. When the particle size of the reaction product is about 7.5±0.5 μm, the stirring speed is 220 r / min. The reaction is stopped when the target particle size of the reaction product reaches 8.3 μm.

[0130] (6) The mixed salt solution, sodium hydroxide solution and ammonia solution are continuously introduced into the reactor. The pH is maintained at 10.6. The temperature is increased from 45°C to 52°C in 10 h. The ammonia concentration is decreased from 7 g / L to 3.8 g / L in 10 h. The flow rate of the mixed salt solution is 600 L / h. The stirring speed is 190 r / min. The reaction is stopped when the target particle size of the reaction product reaches 11 μm.

[0131] (7) The reaction product is subjected to aging, washing, pressure filtration, drying, sieving, demagnetization and packaging processes to obtain a positive electrode material precursor. The chemical formula of the precursor is Ni 0.9 Co 0.05 Mn 0.05 (OH)2.

[0132] Example 5

[0133] (1) prepare an ammonia solution with a concentration of 15 mol / L, a sodium hydroxide solution with a concentration of 12 mol / L, and a mixed salt solution with a concentration of 2.5 mol / L, wherein the mixed salt solution is prepared by dissolving soluble nickel sulfate, soluble cobalt sulfate, and soluble manganese sulfate in water according to a molar ratio of Ni:Co:Mn=88:9:3.

[0134] (2) under a nitrogen atmosphere, control the oxygen content in the reaction kettle to be 0.04%, and the pressure to be 0.5 MPa, and then pass the ammonia solution and the sodium hydroxide solution into the reaction kettle at 60°C and mix them under stirring at a speed of 500 r / min to form a first reaction bottom solution, wherein the ammonia concentration in the first reaction bottom solution is 4 g / L, and the pH is 12.1.

[0135] (3) under the condition of 60°C, pass the mixed salt solution, the sodium hydroxide solution, and the ammonia solution into the reaction kettle containing the first reaction bottom solution in parallel flow, and first maintain the pH of the reaction solution to be 12.1 for 3 h, and then reduce the pH to 11.8 for 7 h, while the stirring speed is first maintained at 500 r / min for 5 h, and then reduced to 440 r / min, the ammonia concentration is maintained at 4 g / L, the flow rate of the mixed salt solution is 380 L / h, and the reaction is stopped until the reaction product grows to a target particle size of 5.5 μm.

[0136] (4) transfer the reaction product to another reaction kettle, pass the ammonia solution and the sodium hydroxide solution into the reaction kettle at 43°C and mix them under stirring at a speed of 280 r / min, so that the solid content is 70 g / L, the pH is 11.3, and the ammonia concentration is 8 g / L.

[0137] (5) under the condition of 43°C, pass the mixed salt solution, the sodium hydroxide solution, and the ammonia solution into the reaction kettle in parallel flow, and control the pH to be reduced from 11.3 to 10.55 in 20 h, the ammonia concentration is maintained at 8 g / L, the flow rate of the mixed salt solution is 1000 L / h, the stirring speed is 320 r / min when the particle size of the reaction product is about 5.5±0.5 μm, the stirring speed is 280 r / min when the particle size of the reaction product is about 6.5±0.5 μm, the stirring speed is 240 r / min when the particle size of the reaction product is about 7.5±0.5 μm, and the reaction is stopped until the reaction product grows to a target particle size of 8.5 μm.

[0138] (6) continue to pass the mixed salt solution, the sodium hydroxide solution, and the ammonia solution into the reaction kettle in parallel flow, control the pH to be maintained at 10.55, the temperature to be increased from 43°C to 53°C in 10 h, the ammonia concentration to be reduced from 8 g / L to 4 g / L in 10 h, the flow rate of the mixed salt solution to be 700 L / h, and the stirring speed to be 200 r / min, and the reaction is ended until the reaction product grows to a target particle size of 12 μm.

[0139] (7) The reaction product is subjected to aging, washing, pressure filtration, drying, sieving, magnetic removal, and packaging procedures to obtain a positive electrode material precursor, the chemical formula of which is Ni 0.88 Co 0.09 Mn 0.03 (OH)2.

[0140] Example 6

[0141] Example 6 differs from Example 1 in that the molar ratio of Ni:Co:Mn in the mixed salt solution is 3:1:1. The chemical formula of the prepared precursor is Ni 0.6 Co 0.2 Mn 0.2 (OH)2.

[0142] Example 7

[0143] Example 7 differs from Example 1 in that the flow rate of the mixed salt solution in step (3) is 250 L / h, and the ammonia concentration is 3.8 g / L, and the flow rate of the mixed salt solution in step (6) is 450 L / h, and the ammonia concentration is 3.8 g / L.

[0144] Example 8

[0145] Example 8 differs from Example 1 in that the stirring speed in step (3) is first maintained at 420 r / min for 8 h, and then reduced to 400 r / min, and the flow rate of the mixed salt solution is 400 L / h.

[0146] Example 9

[0147] Example 9 differs from Example 1 in that the solid content in step (4) is 30 g / L, and the flow rate of the mixed salt solution in step (5) is 1400 L / h.

[0148] Example 10

[0149] Example 10 differs from Example 1 in that the flow rate of the mixed salt solution in step (6) is 800 L / h.

[0150] Comparative Example 1

[0151] Comparative Example 1 differs from Example 1 in that the ammonia concentration in step (4) is 3.5 g / L, and the temperature is 55℃, the ammonia concentration in step (5) is 3.5 g / L, and the temperature is 55℃, and the flow rate of the mixed salt solution is 600 L / h.

[0152] Comparative Example 2

[0153] The difference between Comparative Example 2 and Example 1 is that step (4) is not performed, and after step (3), the mixed salt solution, the sodium hydroxide solution, and the ammonia solution are directly introduced into the reactor at 46°C, the pH is controlled to decrease from 11.6 to 10.5 in 20 h, and step (5) is performed.

[0154] Comparative Example 3

[0155] The difference between Comparative Example 3 and Example 1 is that the same raw materials are used, a first reaction is performed under the conditions of steps (4) and (5) to obtain a reaction product with a particle size of 5 μm, a second reaction is performed under the conditions of step (6) to obtain a reaction product with a particle size of 8 μm, and a third reaction is performed under the conditions of steps (2) and (3) to obtain a reaction product with a particle size of 12 μm.

[0156] The precursors prepared in Examples 1 to 10 and Comparative Examples 1 to 3 are subjected to characterization tests, and the results are shown in FIG. 1, FIG. 5, FIG. 6, and Table 1.

[0157] Table 1

[0158] The reaction products prepared in each step in the preparation processes of Examples 1 to 10 and Comparative Examples 1 to 3 are subjected to characterization tests, and the results are shown in FIG. 2, FIG. 3, FIG. 4, FIG. 7, and Table 2. It should be noted that the thickness and the number of layers of the flaky material in Table 2 refer to the average thickness and the average number of layers, i.e., 10 flaky materials are randomly selected in the electron microscope image, and the average thickness and the average number of layers are calculated.

[0159] Table 2

[0160] As can be seen from FIG. 1 to FIG. 7 and Table 1 and Table 2, the precursors prepared in Examples 1 to 10 all have a unique structure of a compact core and a compact outer shell and a loose intermediate layer, and have a large specific surface area. In Comparative Example 1, the ammonia concentration and the temperature are kept unchanged in steps (4) and (5), and the flow rate of the mixed salt solution in step (5) is only 600 L / h, so that the prepared precursor has a compact interior and a large thickness of the surface multi-layer flaky material, resulting in a small specific surface area of the precursor. In Comparative Example 2, step (4) is not performed, and the particle size of the intermediate layer and the outer layer grows slowly, resulting in a compact structure of the core, the intermediate layer, and the outer layer, and a small specific surface area. In Comparative Example 3, the preparation conditions are different, resulting in that the core is composed of two layers of flaky material with an average thickness of about 72 nm, the structure is loose, the intermediate layer is composed of a plurality of primary flaky materials with an average thickness of about 132 nm, and the structure is compact, and the outer shell is composed of a plurality of primary flaky materials with an average thickness of about 280 nm, and the structure is compact.

[0161] The precursors prepared in Examples 1 to 10 and Comparative Examples 1 to 3 are made into positive electrode materials and assembled into batteries to test the electrical properties.

[0162] The preparation method of the positive electrode material is that lithium hydroxide and the positive electrode material precursor are mixed, then sintered at 430 DEG C for 4h, and then sintered at 800 DEG C for 14h to obtain the positive electrode material, wherein the ratio of the molar content of lithium element in lithium hydroxide to the total molar amount of transition metal elements in the positive electrode material precursor is 1.1:1.

[0163] The preparation method of the battery is that the positive electrode material, the conductive agent carbon black (SP) and the binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 92:4:4 to coat the two functional surfaces of the aluminum foil to form a positive electrode material layer, thereby preparing a positive electrode sheet; the hard carbon, the conductive agent SP and the binder PVDF are mixed in a mass ratio of 4:4:92 to coat the two functional surfaces of the copper foil to form a negative electrode material layer, thereby preparing a negative electrode sheet; the positive electrode sheet, the separator and the negative electrode sheet are stacked to obtain an electrode assembly, the electrode assembly is placed in an aluminum plastic film, a commercial NaPF6 electrolyte is injected, and a battery is obtained.

[0164] The test method and conditions are that the tap density tester is used to test the tap density; the sintering yield refers to the proportion of the number of products meeting the quality requirements to the total number after sintering treatment; the rate performance is the capacity retention rate under high-rate charging and discharging, and the test result corresponds to the discharge specific capacity at 1C rate; the cycle stability is the ratio of the capacity after 100 cycles at 0.2C to the initial capacity, the test voltage is 2.8V-4.2V, and the temperature is 25 DEG C. The test results are shown in Table 3.

[0165] Table 3

[0166] According to Table 3, the precursors prepared in Examples 1 to 10 have high tap density, the positive electrode materials prepared by sintering have high sintering yield, and the batteries can achieve excellent cycle stability and rate performance. Although the precursors prepared in Comparative Examples 1 to 2 have high tap density, they are prone to cracking due to stress during sintering because of small specific surface area, resulting in low yield of the positive electrode materials prepared by sintering and poor rate performance and cycle stability; the precursor prepared in Comparative Example 3 has small tap density because the inner core is loose and the intermediate layer and the shell are compact, resulting in poor yield of the positive electrode material prepared by sintering and reduced rate performance and cycle stability.

[0167] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the present disclosure.

[0168] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific and detailed manner, but should not be construed as limiting the scope of the patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are all within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A positive electrode material precursor, wherein, The positive electrode material precursor has a core-shell structure, comprising an inner core, an outer shell, and an intermediate layer between the inner core and the outer shell; The inner core is composed of a first sheet material stack, and the first sheet material is composed of a plurality of layers of primary sheet material stacked together; The intermediate layer is composed of a primary sheet material stack; The outer shell is composed of a second sheet material stack, and the second sheet material is composed of a plurality of layers of primary sheet material stacked together, and the number of layers of primary sheet material in the second sheet material is less than the number of layers of primary sheet material in the first sheet material; The specific surface area of the positive electrode material precursor is 10 m 2 / g-20 m 2 / g.

2. The positive electrode material precursor according to claim 1, wherein, The number of layers of primary sheet material in the first sheet material is greater than or equal to 5.

3. The positive electrode material precursor of claim 1, wherein, The porosity of the inner core is less than the porosity of the outer shell, and the porosity of the outer shell is less than the porosity of the intermediate layer.

4. The positive electrode material precursor of claim 3, wherein, The positive electrode material precursor satisfies at least one of the following conditions: (1) The porosity of the positive electrode material precursor is 5%-10%; (2) The porosity of the inner core is less than or equal to 2%; (3) The porosity of the intermediate layer is 10%-12%; (4) The porosity of the outer shell is 5%-8%.

5. The positive electrode material precursor of claim 1, wherein, The positive electrode material precursor also satisfies at least one of the following conditions: (1) The average thickness of the first sheet material is 130nm-170nm; (2) The average thickness of the primary sheet material in the intermediate layer is less than or equal to 60nm; (3) The average thickness of the second sheet material is 70nm-120nm; (4) The diameter of the inner core is 3μm-7μm; (5) The thickness of the intermediate layer is 1μm-2.5μm; (6) The thickness of the outer shell is 1μm-4μm; (7) The diameter of the positive electrode material precursor is 7μm-20μm.

6. The positive electrode material precursor of claim 1, wherein, In the X-ray diffraction pattern of the positive electrode material precursor, at least one of the following conditions is satisfied: (1) The diffraction peak intensity of the (001) crystal plane is greater than or equal to 7000cps, and the average grain size of the positive electrode material precursor along the direction perpendicular to the (001) crystal plane is greater than or equal to 10nm; (2) The diffraction peak intensity of the (101) crystal plane is greater than or equal to 7000cps, and the average grain size of the positive electrode material precursor along the direction perpendicular to the (101) crystal plane is greater than or equal to 10nm; (3) The diffraction peak intensity of the (100) crystal plane is greater than or equal to 4000cps, and the average grain size of the positive electrode material precursor along the direction perpendicular to the (100) crystal plane is greater than or equal to 25nm.

7. The cathode material precursor of any one of claims 1 to 6, wherein, The chemical formula of the positive electrode material precursor is Ni x Co y Mn z (OH)2, wherein 0.5≤x≤0.95, 0≤y≤0.25, 0≤z≤0.25, x+y+z=1 and y and z are not simultaneously 0.

8. A method of preparing a cathode material precursor as claimed in any one of claims 1 to 7, wherein, The method comprises the following steps: Prepare an ammonia water solution, a sodium hydroxide solution, and a mixed salt solution; Mix the ammonia water solution and the sodium hydroxide solution to prepare a first reaction bottom liquid and a second reaction bottom liquid, respectively, and the ammonia concentrations of the first reaction bottom liquid and the second reaction bottom liquid are c1 and c2, respectively, c1 Pass the ammonia water solution, the sodium hydroxide solution, and the mixed salt solution into the first reaction bottom liquid in parallel to perform a first reaction, and prepare the inner core, wherein the flow rate of the mixed salt solution is 200L / h-400L / h, the ammonia concentration of the reaction solution during the first reaction is c1, and the reaction temperature is T1; mixing the inner core with the second reaction bottom solution, and continuously feeding ammonia water solution, sodium hydroxide solution and mixed salt solution to carry out a second reaction, to obtain an intermediate, wherein the flow rate of the mixed salt solution is 1000 L / h-1500 L / h, the ammonia concentration of the reaction solution during the second reaction is c2, and the reaction temperature is T2; continuously feeding ammonia water solution, sodium hydroxide solution and mixed salt solution to carry out a third reaction, to obtain the positive electrode material precursor, wherein the flow rate of the mixed salt solution is 400 L / h-800 L / h, the ammonia concentration of the reaction solution during the third reaction is c1, the reaction temperature is T3, and T2<T3<T1.

9. The method of claim 8, wherein the precursor of the cathode material is prepared by the steps of: The first reaction, the second reaction and the third reaction satisfy at least one of the following conditions: (1) the pH of the first reaction bottom solution is greater than the pH of the second reaction bottom solution; (2) the pH of the reaction solution during the first reaction is greater than the pH of the reaction solution during the second reaction; (3) the pH of the reaction solution at the end of the second reaction is equal to the pH of the reaction solution during the third reaction; (4) the stirring speed of the first reaction is greater than the stirring speed of the second reaction; (5) the stirring speed of the second reaction is greater than the stirring speed of the third reaction.

10. The method of claim 8 or claim 9, wherein the method further comprises: The preparation method satisfies at least one of the following conditions: (1) the pH of the first reaction bottom solution is 12.1-12.3, and c1 is 1 g / L-4 g / L; (2) the pH of the second reaction bottom solution is 11.1-11.3, and c2 is 5 g / L-8 g / L; (3) in the first reaction step, T1 is 55°C-60°C, the stirring speed is 400 r / min-500 r / min, the pH of the reaction solution is 11.5-12.3, and the diameter of the inner core is 3 μm-7 μm; (4) in the second reaction step, T2 is 40°C-50°C, the stirring speed is 200 r / min-350 r / min, the pH of the reaction solution at the end of the reaction is 10.5-10.6, and the diameter of the intermediate is 5 μm-12 μm; (5) in the third reaction step, T3 is 50°C-55°C, the stirring speed is 180 r / min-200 r / min, the pH of the reaction solution is 10.5-10.6, and the diameter of the positive electrode material precursor is 7 μm-20 μm.

11. The method of claim 8 to 10, wherein the method further comprises the step of: The preparation method further satisfies at least one of the following conditions: (1) the concentration of the ammonia water solution is 5 mol / L-15 mol / L; (2) the concentration of the sodium hydroxide solution is 9 mol / L-12 mol / L; (3) the concentration of the mixed salt solution is 1.5 mol / L-2.5 mol / L; (4) in the first reaction step, the pH of the reaction solution is maintained at 12.1-12.3 for 1 h-4 h, and then decreased to 11.5-11.8 for 6 h-8 h; (5) in the step of mixing the inner core with the second reaction bottom solution, the solid content is 10 g / L-100 g / L; (6) The preparation method is carried out in a protective atmosphere, the oxygen content is less than or equal to 0.1%, and the pressure is 0.2 MPa-0.7 MPa.

12. A positive electrode material, wherein, Prepared from the positive electrode material precursor according to any one of claims 1-7.

13. A positive electrode sheet, wherein A positive electrode sheet comprising a positive electrode current collector and a positive electrode material layer disposed on a surface of the positive electrode current collector, the positive electrode material layer comprising the positive electrode material according to claim 12.

14. A battery, wherein, A positive electrode sheet comprising the positive electrode sheet according to claim 13.

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