Positive electrode material and preparation method thereof, and lithium ion battery

Abstract

The present application relates to a positive electrode material, a preparation method thereof, and a lithium-ion battery. The positive electrode material includes primary particles, wherein nucleation sites are distributed inside the primary particles, and the nucleation sites include nanoparticles containing at least one of Al, Pb, B, P, Ti, V, Mg, and Zr. The primary particles of the present application have nucleation sites distributed inside and / or on the surface. The presence of the nucleation sites can prevent the agglomeration of the material, buffer the volume change during the charge and discharge process, and enhance the reactive sites on the surface and / or inside the material, thereby increasing the interfacial reaction rate, accelerating the lithium ion transmission rate, and promoting the migration rate of lithium ions into the particle interior, thereby exhibiting excellent performance of high efficiency, high capacity, and long cycle life.

Description

Technical Field

[0001] The present application relates to the technical field of positive electrode materials, and in particular to a positive electrode material and a preparation method thereof, and a lithium-ion battery. Background Art

[0002] In recent years, lithium-ion batteries (LIBs) have been widely used in modern portable electronic devices and have a broad market in hybrid vehicles and pure electric vehicles due to their high specific energy, high operating voltage, long cycle life, no memory effect and environmental friendliness. The positive electrode material is often the bottleneck affecting the energy density of the battery. Layered LiNi 1-x-y Co x M y O2 ternary cathode material combines the advantages of LiCoO2, LiNiO2 and LiMO2, and has the characteristics of high discharge capacity, good cycle life and low cost. It is a cathode material with great application prospects. High nickel cathode materials (Ni≥80%), such as LiNi 0.8 Co 0.1 Mn 0.1 O2 and LiNi 0.8 Co 0.15 Al 0.05 O2 has a high reversible specific capacity (>200mAh / g) and good cycle stability, and is suitable as a positive electrode material for high specific energy power batteries.

[0003] However, high nickel ternary materials also have certain defects:

[0004] 1) Unstable surface properties. Residual lithium on the surface of nickel-rich ternary materials is easily exposed to the air to form impurity phases such as Li2CO3 and LiOH, which increases the alkalinity of the material particles. This will not only bring difficulties to the subsequent coating process, but the insulating impurity phase will also increase the interfacial impedance of the material. In addition, in a deeper delithiation state, the high-valent transition metal ions on the surface of the particles are highly oxidizing and easily react with the electrolyte, resulting in capacity loss. Finally, repeated electrochemical reactions will induce degradation of the surface structure of nickel-rich materials and deteriorate the electrochemical performance.

[0005] 2) Structural defects and lithium nickel mixing. Due to thermodynamic factors, it is difficult to prepare nickel-rich ternary materials that meet the stoichiometric composition. Some Ni 2+ It is easy to migrate to the lithium layer to occupy the lithium site, causing Li + / Ni 2+ Cation mixing. Severe lithium-nickel mixing can affect lithium ion intercalation and deintercalation and electrochemical performance. This structural defect can increase the material's internal resistance and reduce electrochemical activity.

[0006] 3) Intergranular cracks and microstrain. In electrochemical reactions, repeated phase transitions are often accompanied by changes in lattice parameters and the generation of microstress. Newly generated cracks, exposed to the electrolyte, undergo continuous side reactions, forming additional insulating films and even causing pulverization of the electrode material, thereby increasing the material's impedance and reducing its dynamic performance.

[0007] In order to solve the above problems, researchers have carried out a lot of research work. The modification strategies of nickel-rich ternary cathode materials mainly include: surface interface engineering, bulk doping and morphology control. Although these strategies have improved the capacity or cycle stability of the materials to varying degrees, in general, it is still difficult to achieve high discharge specific capacity and structural stability at the same time. Since each transition metal ion has different properties, there is a trade-off between specific capacity, structural stability and thermodynamic stability in nickel-rich ternary cathode materials. Therefore, it is necessary to seek more effective ways to realize the industrial application of nickel-rich ternary cathode materials. Summary of the Invention

[0008] The purpose of this application is to provide a positive electrode material and a preparation method thereof, and a lithium-ion battery, which can reduce the specific surface area of ​​the material, increase the capacity of the positive electrode material while maintaining good safety performance and cycle performance.

[0009] In order to achieve the above-mentioned objectives, in a first aspect, the present application provides a positive electrode material, which includes primary particles, and nucleation sites are distributed inside the primary particles, and the nucleation sites include nanoparticles containing at least one of Al, Pb, B, P, Ti, V, Mg and Zr.

[0010] In one possible embodiment, the positive electrode material further includes at least one of the following features (1) to (8):

[0011] (1) The nucleation sites include at least one of metal oxides and non-metal oxides;

[0012] (2) the nucleation sites include at least one of metal oxides and non-metal oxides, and the nucleation sites include at least one of Al2O3, PbO2, B2O3, P2O5, TiO2, V2O5, MgO and ZrO2;

[0013] (3) The nucleation sites are also distributed on the surface of the primary particles;

[0014] (4) The median particle size of the nucleation sites is 2 nm to 5 nm;

[0015] (5) Crystallization ions are also distributed inside the primary particles;

[0016] (6) Crystallization ions are further distributed inside the primary particles, and the crystallization ions include at least one of aluminum ions, titanium ions, boron ions, and carbon ions;

[0017] (7) The positive electrode material includes secondary particles, and the secondary particles include a plurality of the primary particles;

[0018] (8) The positive electrode material includes secondary particles, and the secondary particles include a plurality of primary particles stacked together.

[0019] In one possible embodiment, the positive electrode material further includes at least one of the following features (1) to (3):

[0020] (1) The content of residual hydroxide in the positive electrode material is less than or equal to 0.2 wt%;

[0021] (2) The content of residual carbonate in the positive electrode material is less than or equal to 0.2 wt%;

[0022] (3) In the XRD test of the positive electrode material, the Bragg diffraction peak intensity ratio R of the (003) crystal plane and the (104) crystal plane of the positive electrode material, wherein, And 1.3≤R≤1.6.

[0023] In one possible embodiment, the positive electrode material includes at least one of the following features (1) to (6);

[0024] (1) The general chemical formula of the positive electrode material is:

[0025] Li a Ni x Co y Mn 1-x-y O2 (Ⅰ)

[0026] In formula (I), 0.95≦a﹤1.05, 0.8≦x﹤0.95, 0.05≦y≦0.2;

[0027] (2) The ionic conductivity of the positive electrode material is greater than or equal to 1.12·10 -9 cm 2 / s;

[0028] (3) The particle strength of the positive electrode material is greater than or equal to 35 MPa;

[0029] (4) The median particle size of the positive electrode material is 3 μm to 4.5 μm;

[0030] (5) The specific surface area of ​​the positive electrode material is 0.4 m 2 / g~0.5m 2 / g;

[0031] (6) The moisture content of the positive electrode material is less than or equal to 400 ppm.

[0032] In a second aspect, an embodiment of the present application provides a method for preparing a positive electrode material, comprising the following steps:

[0033] Mixing a mixture containing a lithium source, a nickel source, a cobalt source, a manganese source and an M compound with a surfactant to obtain a first precursor;

[0034] Subjecting the first precursor to a spray pyrolysis treatment to obtain a second precursor;

[0035] The second precursor is heat-treated to obtain a positive electrode material.

[0036] In one possible embodiment, the preparation method includes at least one of the following features (1) to (15):

[0037] (1) The lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium acetate, lithium oxalate, lithium sulfate, lithium chloride and lithium nitrate;

[0038] (2) The median particle size of the lithium source is 3 μm to 5 μm;

[0039] (3) The nickel source comprises at least one of nickel carbonate, nickel acetate, nickel oxalate, nickel nitrate, nickel chloride and nickel nitrate;

[0040] (4) The median particle size of the nickel source is 3 μm to 5 μm;

[0041] (5) The cobalt source includes at least one of cobalt carbonate, cobalt acetate, cobalt oxalate, cobalt sulfate, cobalt chloride and cobalt nitrate;

[0042] (6) The median particle size of the cobalt source is 3 μm to 5 μm;

[0043] (7) The manganese source includes at least one of manganese carbonate, manganese acetate, manganese oxalate, manganese sulfate, manganese chloride and manganese nitrate;

[0044] (8) The median particle size of the manganese source is 3 μm to 5 μm;

[0045] (9) The M element in the M compound includes at least one of Al, Pb, B, P, Ti, V, Mg and Zr;

[0046] (10) The M compound includes at least one of carbonate, acetate, nitrate, hydrochloride, sulfate and hydroxide;

[0047] (11) The median particle size of the M compound is 1 nm to 3 nm;

[0048] (12) The mass proportion of the M compound in the first precursor is 500 ppm to 3000 ppm;

[0049] (13) The stoichiometric ratio of the lithium source, nickel source and manganese source is Li a Ni x Co y Mn 1-x-y O2, 0.95≦a﹤1.05, 0.8≦x﹤0.95, 0.05≦y≦0.2;

[0050] (14) The surfactant comprises at least one of sodium alginate, polyvinyl pyrrolidone, polyethylene glycol, polyacrylonitrile and chitosan;

[0051] (15) The mass ratio of the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound to the surfactant is 1: (0.01-0.05).

[0052] In one possible implementation, the method includes at least one of the following features (1) to (6):

[0053] (1) before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, a complexing agent is added;

[0054] (2) before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, a complexing agent is added, wherein the complexing agent comprises at least one of phosphate, alcoholamine salt, aminocarboxylate, hydroxycarboxylate, organic phosphate and polyacrylate;

[0055] (3) before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, a complexing agent is added, and the mass of the complexing agent is 1% to 5% of the mass of the first precursor;

[0056] (4) the step of adding an additive before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant;

[0057] (5) before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, an additive is added, wherein the additive comprises at least one of a titanium-boron alloy, a titanium-carbon alloy and a titanium alloy compound;

[0058] (6) Before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, the step of adding an additive is included, and the mass of the additive is 0.1% to 0.3% of the mass of the first precursor.

[0059] In one possible implementation, the method includes at least one of the following features (1) to (4):

[0060] (1) The solvent of the spray pyrolysis treatment includes at least one of water and ethanol;

[0061] (2) The solvent for the spray pyrolysis treatment includes at least one of water and ethanol, and the solid content of the first precursor in the solvent is 20% to 70%;

[0062] (3) The temperature of the spray pyrolysis treatment is 500° C. to 800° C.;

[0063] (4) The injection rate of the spray pyrolysis treatment is 20 mL / min to 80 mL / min.

[0064] In one possible implementation, the method includes at least one of the following features (1) to (4):

[0065] (1) The atmosphere of the heat treatment includes at least one of air and oxygen;

[0066] (2) The temperature of the heat treatment is 700° C. to 1000° C.;

[0067] (3) The heating rate of the heat treatment is 1°C / min to 5°C / min;

[0068] (4) The heat treatment holding time is 10h to 24h.

[0069] In a third aspect, the present application provides a lithium-ion battery, which includes the positive electrode material described in the first aspect or the positive electrode material prepared by the method described in the second aspect.

[0070] Compared with the prior art, the present application has the following beneficial effects: in the positive electrode material of the present application, nucleation sites are distributed inside the primary particles, and the nucleation sites include nanoparticles containing at least one element of Al, Pb, B, P, Ti, V, Mg and Zr. The presence of the above-mentioned nucleation sites can avoid the agglomeration of the material, and can enhance the reaction active sites inside the material, increase the interface reaction rate, accelerate the lithium ion transmission rate, and promote the migration rate of lithium ions to the interior of the particles, so that the positive electrode material has excellent performance of high efficiency, high capacity and long cycle. In addition, the presence of the above-mentioned nucleation sites significantly improves the electrical conductivity of the positive electrode material, thereby improving the ion transmission ability of the material, improving the structural stability of the material during the charge and discharge process, and is beneficial to buffering the volume change of the positive electrode material during the charge and discharge process. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0072] Figure 1 This is a flow chart for preparing the positive electrode material of this application;

[0073] Figure 2 These are scanning electron microscope images of the cathode material of Example 3 of the present application at different magnifications;

[0074] Figure 3 The scanning electron microscope images of the positive electrode material of Comparative Example 1 at different magnifications are shown;

[0075] Figure 4 This is a comparison chart of the first-week charge-discharge curves of the positive electrode materials of Example 3 and Comparative Example 1 of the present application;

[0076] Figure 5 The capacity retention rate of the positive electrode material 1C after 50 cycles of Example 3 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0077] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0078] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0079] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0080] In order to facilitate understanding of the present application, specific terms are appropriately defined in the present application. Unless otherwise defined herein, the scientific terms and technical terms used in the present application have the meanings commonly understood by those skilled in the art to which the present application belongs.

[0081] The present application provides a positive electrode material, which includes primary particles, wherein nucleation sites are distributed inside the primary particles, and the primary particles contain nanoparticles of at least one of Al, Pb, B, P, Ti, V, Mg and Zr.

[0082] In the above scheme, in the positive electrode material of the present application, nucleation sites are distributed inside the primary particles, and the nucleation sites include nanoparticles containing at least one of Al, Pb, B, P, Ti, V, Mg and Zr. The presence of the above nucleation sites can avoid the agglomeration of the material, and can enhance the reaction active sites inside the material, increase the interface reaction rate, accelerate the lithium ion transmission rate, and promote the migration rate of lithium ions to the interior of the particles, so that the positive electrode material has excellent performance of high efficiency, high capacity and long cycle. In addition, the presence of the above nucleation sites significantly improves the electrical conductivity of the positive electrode material, thereby improving the ion transmission ability of the material, improving the structural stability of the material during the charge and discharge process, and is beneficial to buffering the volume change of the positive electrode material during the charge and discharge process.

[0083] In this application, nucleation sites refer to regularly ordered groups formed on the surface or inside the material. These groups can preferentially bind to ions in the solution and enrich them. After reaching a certain critical size, they become crystal nuclei that can exist stably and grow spontaneously. The existence of the above-mentioned crystal nuclei can promote the transmission of lithium ions.

[0084] In some embodiments, the nucleation sites are distributed in a discrete manner within or on the surface of the primary particles.

[0085] In some embodiments, the nucleation sites include at least one of a metal oxide and a non-metal oxide.

[0086] In some embodiments, the nucleation sites include at least one of Al2O3, PbO2, B2O3, P2O5, TiO2, V2O5, MgO, and ZrO2.

[0087] In some embodiments, the nucleation sites are also distributed on the surface of the primary particles, that is, the nucleation sites may be distributed only inside the primary particles, or the nucleation sites may be distributed simultaneously inside and on the surface of the primary particles.

[0088] In some embodiments, the median particle size of the nucleation sites is between 2 nm and 5 nm. Specifically, it can be 2 nm, 3 nm, 4 nm, 5 nm, or other values ​​within the above range, which are not limited herein. If the median particle size of the nucleation sites is greater than 5 nm, the nucleation sites on the surface of the primary particles are prone to forming a coating layer, resulting in a decrease in the conductivity of the material. If the median particle size of the nucleation sites is less than 2 nm, the effect of improving the conductivity of the material is limited.

[0089] In some embodiments, crystallization ions are further distributed within the primary particles, and the crystallization ions include at least one of aluminum ions, titanium ions, boron ions, and ions. The presence of these crystallization ions can facilitate heterogeneous nucleation of the material particles, thereby increasing the crystallization rate of the material. Furthermore, the presence of the crystallization ions can further refine the crystalline structure of the material, thereby reducing the diameter of the crystal spheres.

[0090] In some embodiments, the positive electrode material includes secondary particles. It can be understood that the primary particles are single fine grains, and the secondary particles are particles formed by the agglomeration of primary particles. Preferably, the secondary particles are aggregates formed by the agglomeration of primary particles after coating. The positive electrode material of the present application can be primary particles, secondary particles, or a mixture of primary particles and secondary particles.

[0091] In some embodiments, the content of residual alkali hydroxide in the positive electrode material is less than or equal to 0.2 wt%. Specifically, the content of residual alkali hydroxide in the positive electrode material can be 0.05 wt%, 0.1 wt%, 0.15 wt% and 0.2 wt%, etc., or other values ​​within the above range, which are not limited here.

[0092] In some embodiments, the content of residual alkali carbonate in the positive electrode material is less than or equal to 0.2 wt%. Specifically, the content of residual alkali carbonate in the positive electrode material can be 0.05 wt%, 0.1 wt%, 0.15 wt% and 0.2 wt%, etc., or other values ​​within the above range, which are not limited here.

[0093] Controlling the mass content of residual hydroxide and residual carbonate in the positive electrode material within the above range is beneficial to improving the processing performance of the positive electrode material and reducing the gas production of the battery prepared with the positive electrode material.

[0094] In the XRD test of the positive electrode material, the Bragg diffraction peak intensity ratio R of the (003) crystal plane and the (104) crystal plane of the positive electrode material is And 1.4≤R≤1.6. Specifically, the R value can be 1.4, 1.5, 1.6, etc., or other values ​​within the above range, which are not limited here. Controlling the R value within the above range can reduce the degree of lithium-nickel mixing in the material.

[0095] In some embodiments, the positive electrode material has the general chemical formula Li a Ni x Co y Mn 1-x-y O2, 0.95≦a﹤1.05, 0.8≦x﹤0.95, 0.05≦y≦0.2.

[0096] In some embodiments, the ionic conductivity of the positive electrode material is greater than or equal to 1.12·10-9 cm 2 / s, specifically, the ionic conductivity of the positive electrode material can be 1.12·10 -9 cm 2 / s, 1.12·10 -8 cm 2 / s, 1.10 -8 cm 2 / s and 5.10 -7 cm 2 / s, etc., and may also be other values ​​within the above range, which are not limited here. The ionic conductivity within the above range is beneficial to improving the conductivity of the positive electrode material.

[0097] In some embodiments, the particle strength of the positive electrode material is greater than or equal to 35 MPa. Specifically, the particle strength of the positive electrode material can be 35 MPa, 40 MPa, 45 MPa, 60 MPa, 55 MPa, and 60 MPa, etc., or other values ​​within the above range, which are not limited here.

[0098] In some embodiments, the median particle size of the positive electrode material is 3 μm to 4.5 μm. Specifically, the median particle size of the positive electrode material can be 3 μm, 3.2 μm, 3.5 μm, 3.7 μm, 3.9 μm, 4.0 μm, 4.2 μm, 4.4 μm and 4.5 μm, etc., or other values ​​within the above range, which are not limited here.

[0099] In some embodiments, the specific surface area of ​​the positive electrode material is 0.4 m 2 / g~0.5m 2 / g, specifically, the specific surface area of ​​the positive electrode material is 0.4m 2 / g, 0.41m 2 / g, 0.42m 2 / g, 0.43m 2 / g, 0.44m 2 / g, 0.45m 2 / g, 0.46m 2 / g, 0.47m 2 / g, 0.48m 2 / g, 0.49m 2 / g and 0.5m 2 / g, etc., and may also be other values ​​within the above range, which are not limited here.

[0100] In some embodiments, the moisture content of the positive electrode material is less than or equal to 400 ppm. Specifically, the moisture content of the positive electrode material can be 400 ppm, 350 ppm, 300 ppm, 250 ppm, 200 ppm, 150 ppm, etc., or other values ​​within the above range, which are not limited herein. Ppm refers to mass concentration.

[0101] The present application also provides a method for preparing a positive electrode material, comprising the following steps:

[0102] Mixing a mixture containing a lithium source, a nickel source, a cobalt source, a manganese source and an M compound with a surfactant to obtain a first precursor;

[0103] The first precursor is subjected to spray pyrolysis treatment to obtain a second precursor;

[0104] The second precursor is heat-treated to obtain a positive electrode material.

[0105] In the above scheme, the present application mixes a mixture containing a lithium source, a nickel source, a cobalt source, a manganese source and an M compound with a surfactant, and the surfactant undergoes a colloid reaction in the above mixture to form a thermodynamically stable colloidal solution. By means of thermal Brownian motion in the colloidal solution, adsorption occurs between the materials in the mixture, and a close combination at the microscopic level can be achieved, thereby obtaining a first precursor. The first precursor is then subjected to a spray pyrolysis treatment so that the first precursor can instantly form primary particles (i.e., the second precursor). The preparation of primary particles by spray pyrolysis can reduce the grain boundary segregation phenomenon of the material (when forming a grain structure, at the interface between the grains, the ions deviate from the equilibrium concentration value, and grain boundary cracks will appear during the cycle, leading to the occurrence of side reactions), promote the reduction of grain boundary cracks and interface resistance of the material, and thus improve the electrical conductivity of the material. Finally, the second precursor is heat-treated to obtain the positive electrode material. In the positive electrode material of the present application, nucleation sites containing M elements are distributed inside the primary particles. The presence of the above-mentioned nucleation sites can avoid the agglomeration of the material, and can enhance the reaction active sites inside the material, increase the interfacial reaction rate, accelerate the lithium ion transmission rate, and promote the migration rate of lithium ions to the interior of the particles, so that the positive electrode material has excellent performance of high efficiency, high capacity and long cycle.

[0106] The preparation method of this application is described in detail below:

[0107] Step S101: mixing a mixture containing a lithium source, a nickel source, a cobalt source, a manganese source and an M compound with a surfactant to obtain a first precursor.

[0108] In some embodiments, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium acetate, lithium oxalate, lithium sulfate, lithium chloride, and lithium nitrate.

[0109] In some embodiments, the median particle size of the lithium source is 3 μm to 5 μm. Specifically, the median particle size of the lithium source can be 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc., or other values ​​within the above range, which are not limited here.

[0110] In some embodiments, the cobalt source includes at least one of cobalt carbonate, cobalt acetate, cobalt oxalate, cobalt sulfate, cobalt chloride, and cobalt nitrate.

[0111] In some embodiments, the median particle size of the cobalt source is 3 μm to 5 μm. Specifically, the median particle size of the cobalt source can be 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc., or other values ​​within the above range, which are not limited here.

[0112] In some embodiments, the manganese source includes at least one of manganese carbonate, manganese acetate, manganese oxalate, manganese sulfate, manganese chloride, and manganese nitrate.

[0113] In some embodiments, the median particle size of the manganese source is 3 to 5 μm. Specifically, the median particle size of the manganese source can be 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc., or other values ​​within the above range, which are not limited here.

[0114] In some embodiments, the nickel source includes at least one of nickel carbonate, nickel acetate, nickel oxalate, nickel nitrate, nickel chloride, and nickel nitrate.

[0115] In some embodiments, the median particle size of the nickel source is 3 μm to 5 μm. Specifically, the median particle size of the lithium source can be 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc., or other values ​​within the above range, which are not limited here.

[0116] In some embodiments, the M element in the M compound includes at least one of Al, Pb, B, P, Ti, V, Mg, and Zr.

[0117] In some embodiments, the M compound includes at least one of carbonate, acetate, nitrate, hydrochloride, and sulfate. For example, the M compound can be magnesium sulfate, zirconium hydroxide, magnesium acetate, titanium oxide, aluminum hydroxide, and the like.

[0118] In some embodiments, the median particle size of the M compound is 1 nm to 3 nm. Specifically, the median particle size of the M compound can be 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, etc., or other values ​​within the above range, which are not limited here.

[0119] In some embodiments, the mass proportion of the M compound in the first precursor is 500ppm to 3000ppm. Specifically, the mass proportion of the M compound in the first precursor can be 500ppm, 800ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm and 3000ppm, etc., or other values ​​within the above range, which are not limited here.

[0120] The present application helps to obtain primary particles with smaller particle sizes by controlling the particle size of the raw materials, thereby making the specific surface area of ​​the prepared material smaller, which is beneficial to improving the capacity of the material.

[0121] In some embodiments, the stoichiometric ratio of the lithium source, nickel source, cobalt source, and manganese source is Li a Ni x Co y Mn 1-x-y O2, 0.95≦a﹤1.05, 0.8≦x﹤0.95, 0.05≦y≦0.2.

[0122] In some embodiments, the surfactant includes at least one of sodium alginate, polyvinyl pyrrolidone, polyethylene glycol, and polyacrylonitrile. Such surfactants can reduce the surface tension of the solvent, thereby reducing the free energy of the system, allowing the molecules or ions to dissolve in each other, forming a uniform medium, and facilitating the formation of tightly bound primary particles.

[0123] In some embodiments, the mass ratio of the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound to the surfactant is 1:(0.01~0.05). Specifically, the mass ratio of the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound to the surfactant can be 1:0.01, 1:0.002, 1:0.03, 1:0.04 and 1:0.05, etc., or other values ​​within the above range, which are not limited here.

[0124] In some embodiments, before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, a step of adding a complexing agent is also included, that is, step S100 is: mixing the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound with the surfactant and the complexing agent to obtain a first precursor.

[0125] In some embodiments, the complexing agent includes at least one of phosphate, alcoholamine salt, aminocarboxylate, hydroxycarboxylate, organic phosphate, and polyacrylate. The addition of the complexing agent can cause adsorption between the materials in the solution, thereby achieving close microscopic bonding.

[0126] In some embodiments, the mass of the complexing agent is 1% to 5% of the mass of the first precursor. Specifically, the mass of the complexing agent is 1%, 2%, 3%, 4% and 5% of the mass of the first precursor, etc., and can also be other values ​​within the above range, which is not limited here.

[0127] In some embodiments, the step of adding an additive is further included before the mixture containing the lithium source, nickel source, cobalt source, manganese source, and M compound is mixed with the surfactant. Specifically, step S100 is: mixing the mixture containing the lithium source, nickel source, cobalt source, manganese source, and M compound with the surfactant, complexing agent, and additive to obtain a first precursor.

[0128] In some embodiments, the additive includes at least one of an aluminum-titanium-boron alloy, an aluminum-titanium-carbon alloy, and an aluminum-titanium alloy compound. The addition of the above-mentioned additives can cause the M compound to heterogeneously nucleate at a higher temperature, reduce the energy required for material nucleation, increase the crystallization rate, make the nucleation site more easily formed inside the material, and simultaneously allow the reactants to crystallize at high temperatures, thereby shortening the processing cycle and improving the product texture. The additive can further refine the crystalline structure of the first precursor, that is, adding the additive can increase the crystallinity of the first precursor, reduce the diameter of the spherulites, and control a certain morphology. Reducing the diameter of the spherulites of the first precursor and controlling a certain morphology can reduce the specific surface area of ​​the material, thereby increasing the capacity of the material. Compared with the selection of metal additives, the alloy selected in this application has a significant grain refinement effect and high refinement efficiency. After addition, a uniform nucleation center is formed, which quickly exerts a refinement effect. In addition, the addition of the alloy can also improve the processing performance and mechanical properties of the material, and improve the stability of product quality.

[0129] In some embodiments, the mass of the additive is 0.1% to 0.3% of the mass of the first precursor. Specifically, the mass of the additive is 0.1%, 0.2%, and 0.3% of the mass of the first precursor, etc. It can also be other values ​​within the above range, which is not limited here.

[0130] Step S200: spray pyrolysis the first precursor to obtain a second precursor.

[0131] In some embodiments, the solvent of the spray pyrolysis process includes at least one of water and ethanol.

[0132] In some embodiments, the solid content of the first precursor in the solvent is 20% to 70%. Specifically, the solid content of the first precursor in the solvent can be 20%, 30%, 40%, 50%, 60% and 70%, etc., or other values ​​within the above range, which are not limited here. Controlling the solid content of the first precursor in the solvent within the above range is beneficial to controlling the particle size and shape of the material, thereby reducing agglomeration.

[0133] In some embodiments, the spray pyrolysis temperature is between 500°C and 800°C. Specifically, the spray pyrolysis temperature can be 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, and 800°C, or other values ​​within the above range, without limitation. Controlling the spray pyrolysis temperature within the above range helps ensure optimal material performance. If the temperature is below 500°C, particle adhesion is likely to occur; if the temperature exceeds 800°C, the particle size becomes larger, affecting the electrochemical performance of the material.

[0134] In some embodiments, the injection rate of the spray pyrolysis treatment is 20 mL / min to 80 mL / min. Specifically, the injection rate of the spray pyrolysis treatment can be 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min and 80 mL / min, etc., or other values ​​within the above range, which are not limited here. Controlling the injection rate of the spray pyrolysis treatment within the above range can reduce the adhesion of the material.

[0135] Step S300: heat-treating the second precursor to obtain a positive electrode material.

[0136] In some embodiments, the heat treatment atmosphere includes at least one of air and oxygen.

[0137] In some embodiments, the heat treatment temperature is 700°C to 1000°C. Specifically, the heat treatment temperature can be 700°C, 750°C, 800°C, 850°C, 900°C, 950°C and 1000°C, etc., or other values ​​within the above range, which are not limited here.

[0138] In some embodiments, the heating rate of the heat treatment is 1°C / min to 5°C / min. Specifically, the heating rate of the heat treatment can be 1°C / min, 2°C / min, 3°C / min, 4°C / min and 5°C / min, etc., or other values ​​within the above range, which are not limited here.

[0139] In some embodiments, the holding time of the heat treatment is 10 hours to 24 hours. Specifically, the holding time of the heat treatment can be 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, and 24 hours, etc., or other values ​​within the above range, which are not limited here.

[0140] An embodiment of the present application also provides a lithium-ion battery, comprising a positive electrode plate, a negative electrode plate, a separator, a non-aqueous electrolyte and a casing, wherein the positive electrode plate comprises a current collector and a positive electrode material such as the above-mentioned positive electrode material or a positive electrode material prepared by the above-mentioned method for preparing the positive electrode material, coated on the current collector.

[0141] The following further illustrates the embodiments of the present application in multiple embodiments. The embodiments of the present application are not limited to the following specific embodiments. Within the scope of the unchanged main rights, appropriate changes can be made to the implementation.

[0142] Example 1

[0143] 1) According to the stoichiometric ratio of LiNi 0.8 Co 0.1 Mn 0.1 O2 weighed 27.49 g of lithium sulfate (D50 was 3.5 nm to 4 nm), 61.9 g of nickel sulfate (D50 was 3.5 nm to 4 nm), 7.75 g of cobalt sulfate (D50 was 3.5 nm to 4 nm), and 3.76 g of manganese sulfate (D50 was 3.5 nm to 4 nm), and the above materials were mixed with 0.31 g of magnesium sulfate (D50 was 1.5 nm to 2 nm), 5.24 g of citric acid, 0.524 g of titanium boride alloy, and 1.01 g of sodium alginate to obtain a first precursor;

[0144] 2) The first precursor was placed in a stirring tank, 1000 mL of deionized water was added, and the mixture was stirred for 3 h before spray pyrolysis at a temperature of 700° C. and a feed rate of 20 mL / min to obtain a second precursor.

[0145] 3) The second precursor was calcined at 700° C. for 15 h in an oxygen atmosphere in an atmosphere furnace with a heating rate of 2° C. / min, and then cooled to room temperature to obtain a positive electrode material.

[0146] Example 2

[0147] 1) According to the stoichiometric ratio Li 0.95 Ni 0.8 Co 0.15 Mn 0.05 O2 weighed 31.35g of lithium acetate (D50 is 3.5nm~4nm), 47.50g of nickel acetate (D50 is 3.5nm~4nm), 13.28g of cobalt acetate (D50 is 3.5nm~4nm), and 4.33g of manganese acetate (D50 is 3.5nm~4nm), and the above materials were mixed with 0.2g of zirconium hydroxide (D50 is 1.5nm~2nm), 4.91g of polyethylene glycol, 0.19g of titanium boride alloy, and 1.51g of sodium alginate to obtain a first precursor.

[0148] 2) The first precursor was placed in a stirring tank, 1000 mL of deionized water was added, and the mixture was stirred for 3 h before spray pyrolysis at a temperature of 750°C and a feed rate of 20 mL / min to obtain the second precursor.

[0149] 3) The second precursor was calcined at 700° C. for 15 h in an oxygen atmosphere in an atmosphere furnace with a heating rate of 2° C. / min, and then cooled to room temperature to obtain a positive electrode material.

[0150] Example 3

[0151] 1) According to the stoichiometric ratio Li 1.05 Ni 0.85 Co 0.05 Mn 0.1 O2 weighed 34.65g of lithium acetate (D50 is 3.5nm~4nm), 50.50g of nickel acetate (D50 is 3.5nm~4nm), 4.43g of cobalt acetate (D50 is 3.5nm~4nm), and 8.65g of manganese acetate (D50 is 3.5nm~4nm), and mixed the above materials with 0.1g of titanium oxide (D50 is 1nm~1.5nm), 4.957g of polyvinyl pyrrolidone, and 0.29g of aluminum-titanium-boron alloy to obtain a first precursor.

[0152] 2) The first precursor was placed in a stirring tank, 1000 mL of deionized water was added, and the mixture was stirred for 3 h before spray pyrolysis at a temperature of 800° C. and a feed rate of 20 mL / min to obtain a second precursor.

[0153] 3) The second precursor was calcined at 750° C. for 15 h in an oxygen atmosphere in an atmosphere furnace with a heating rate of 1° C. / min, and then cooled to room temperature to obtain a positive electrode material.

[0154] Example 4

[0155] 1) According to the stoichiometric ratio Li 0.97 Ni 0.83 Co 0.11 Mn 0.06 O2 weighed 17.92g of lithium carbonate (D50 is 3.5nm~4nm), 49.26g of nickel carbonate (D50 is 3.5nm~4nm), 10.06g of cobalt nitrate (D50 is 3.5nm~4nm), and 6.12g of manganese acetate (D50 is 3.5nm~4nm), and the above materials were mixed with 0.15g of magnesium acetate (D50 is 2nm~2.5nm), 0.4208g of polyacrylonitrile, 0.17g of titanium carbide alloy, and 2.01g of polyvinyl pyrrolidone to obtain a first precursor.

[0156] 2) The first precursor was placed in a stirring tank, 1000 mL of deionized water was added, and the mixture was stirred for 3 h before spray pyrolysis at a temperature of 800° C. and a feed rate of 20 mL / min to obtain a second precursor.

[0157] 3) The second precursor was calcined at 750° C. for 15 h in an oxygen atmosphere in an atmosphere furnace with a heating rate of 1° C. / min, and then cooled to room temperature to obtain a positive electrode material.

[0158] Example 5

[0159] (1) According to the stoichiometric ratio Li 1.01 Ni 0.8 Co 0.1 Mn 0.1 O2 weighed 12.09g of lithium hydroxide (D50 is 4nm~4.5nm), 73.08g of nickel nitrate (D50 is 4nm~4.5nm), 9.15g of cobalt nitrate (D50 is 4nm~4.5nm), and 9.38g of manganese nitrate (D50 is 4nm~4.5nm), and the above materials were mixed with 0.4g of aluminum hydroxide (D50 is 2.5nm~3nm), 0.5259g of polyacrylonitrile, 0.5259g of titanium carbide alloy, and 2.53g of polyvinyl pyrrolidone to obtain a first precursor.

[0160] (2) The first precursor was placed in a stirring tank, 1000 mL of deionized water was added, and the mixture was stirred for 3 h before spray pyrolysis at a temperature of 500 °C and a feed rate of 20 mL / min to obtain the second precursor.

[0161] (3) The second precursor was calcined at 750°C for 15 h in an oxygen atmosphere in an atmosphere furnace with a heating rate of 1°C / min, and then cooled to room temperature to obtain the positive electrode material.

[0162] Example 6

[0163] Different from Example 1, the temperature of the spray pyrolysis in step (2) is 480°C.

[0164] Example 7

[0165] Different from Example 1, the temperature of the spray pyrolysis in step (2) is 830°C.

[0166] Example 8

[0167] Different from Example 1, citric acid is not added in step (1).

[0168] Example 9

[0169] Different from Example 1, titanium boride is not added in step (1).

[0170] Example 10

[0171] 1) According to the stoichiometric ratio Li 1.01 Ni 0.8 Co 0.1 Mn 0.1O2 weighed 12.09g of lithium hydroxide (D50 is 3.5nm~4nm), 73.08g of nickel nitrate (D50 is 3.5nm~4nm), 9.15g of cobalt nitrate (D50 is 3.5nm~4nm), and 9.38g of manganese nitrate (D50 is 3.5nm~4nm), and the above materials were mixed with 0.4g of aluminum hydroxide (D50 is 1.2nm~1.5nm), 0.5259g of polyacrylonitrile, 0.5259g of titanium carbide alloy, and 2.53g of polyvinyl pyrrolidone to obtain a first precursor.

[0172] (2) The first precursor was placed in a stirring tank, 1000 mL of deionized water was added, and the mixture was stirred for 3 h before spray pyrolysis at a temperature of 500 °C and a feed rate of 20 mL / min to obtain the second precursor.

[0173] (3) The second precursor was calcined at 750°C for 15 h in an oxygen atmosphere in an atmosphere furnace with a heating rate of 1°C / min, and then cooled to room temperature to obtain the positive electrode material.

[0174] Example 11

[0175] (1) According to the stoichiometric ratio Li 1.01 Ni 0.8 Co 0.1 Mn 0.1 O2 weighed 12.09g of lithium hydroxide (D50 is 3.5nm~4nm), 73.08g of nickel nitrate (D50 is 3.5nm~4nm), 9.15g of cobalt nitrate (D50 is 3.5nm~4nm), and 9.38g of manganese nitrate (D50 is 3.5nm~4nm), and mixed the above materials with 0.4g of aluminum hydroxide (D50 is 5.5nm~6nm) to obtain a first precursor.

[0176] (2) The first precursor was placed in a stirring tank, 1000 mL of deionized water was added, and the mixture was stirred for 3 h before spray pyrolysis at a temperature of 500 °C and a feed rate of 20 mL / min to obtain the second precursor.

[0177] (3) The second precursor was calcined at 750°C for 15 h in an oxygen atmosphere in an atmosphere furnace with a heating rate of 1°C / min, and then cooled to room temperature to obtain the positive electrode material.

[0178] Comparative Example 1

[0179] Different from Example 1, magnesium sulfate and titanium boride are not added in step (1).

[0180] Comparative Example 2

[0181] Different from Example 2, zirconium hydroxide and titanium boride are not added in step (2).

[0182] Comparative Example 3

[0183] Different from Example 3, titanium oxide and aluminum titanium boron are not added in step (2).

[0184] Comparative Example 4

[0185] Different from Example 4, magnesium acetate and titanium carbide are not added in step (2).

[0186] Comparative Example 5

[0187] Different from Example 5, aluminum hydroxide and titanium carbide are not added in step (2).

[0188] Test method:

[0189] (1) The particle size of the material, including D50, was measured using a Malvern laser particle size analyzer MS 2000.

[0190] (2) The morphology of the positive electrode material is analyzed using a scanning electron microscope to obtain its scanning electron microscope image.

[0191] (3) The specific surface area of ​​the material was tested using Micromeritics Tristar 3020.

[0192] (4) The ionic conductivity of the material was tested using a conductivity tester (model: FT-8100C).

[0193] (5) Use a rapid moisture meter (model: Metrohm 831-860) to test the moisture content of the material.

[0194] (6) Perform XRD test on the positive electrode material synthesized above.

[0195] (7) The residual alkali content of the sample was tested using an automatic potentiometric titrator (model: METTLER TOLEDO G20).

[0196] (8) The electrochemical cycle performance was tested by the following method: 0.8 g of material, 0.1 g of conductive carbon black, and 0.1 g of polyvinylidene fluoride were weighed and placed in a ball mill, 15 mL of N-methylpyrrolidone was added, and the mixture was ball milled to form a uniform slurry, which was then evenly coated on aluminum foil and vacuum dried at 80 ° C for 12 h to obtain a positive electrode. The positive electrode sheets prepared in Example 1 and Comparative Example 1 were pressed into 12 mm discs and assembled into 2016 batteries in a glove box (H2O, O2 < 0.1 ppm), with the positive electrode sheet as the positive electrode, the metal lithium sheet as the counter electrode, the diaphragm as the PP diaphragm, and the electrolyte as 1 MLiPF6 / EC:DEC (1:1). After the assembled battery was left to stand for 12 h, its electrochemical performance was tested on a blue light system (voltage range of 3-4.3 V, temperature of 25 ° C).

[0197] Table 1. Physicochemical properties of cathode materials of Examples and Comparative Examples

[0198]

[0199]

[0200] Table 2. Electrochemical properties of cathode materials of Examples and Comparative Examples

[0201]

[0202] The electrochemical performance data of Example 1 and Comparative Example 1 are shown in Table 1. The electrochemical performance of Example 1 is significantly better than that of Comparative Example 1, indicating that the nucleation sites of the present application have significantly improved the electrochemical performance of the material, and the capacity and cycle efficiency after modification have been significantly improved. Figure 2 As shown by Figure 2 It can be seen that the discharge capacity of the positive electrode material containing nucleation sites in the present application is significantly better than that of Comparative Example 1.

[0203] The residual alkali and moisture data of Example 1 and Comparative Example 1 are shown in Table 2. The moisture and residual alkali of Example 1 are significantly lower than those of Comparative Example 1, indicating that the nucleation sites of the present application have significantly improved the surface properties of the material, which is beneficial to reducing the moisture and residual alkali on the surface of the material; in addition, after the prepared positive electrode material is placed in the atmospheric environment for a certain period of time, the modified material has no significant changes in moisture or residual alkali, while the moisture and residual alkali of the positive electrode material prepared in Comparative Example 1 increase significantly over time, and the surface properties also change significantly, indicating that the positive electrode material containing nucleation sites in the present application has good storage performance.

[0204] The SEM of Example 1 and Comparative Example 1 are as follows: Figure 3 As shown, Figure 3 a is the SEM image of the positive electrode material of Example 1, Figure 3 b is an SEM image of the positive electrode material of Comparative Example 1. It can be clearly seen that the surface of the positive electrode material of Comparative Example 1 is rougher than the surface of the positive electrode material containing nucleation sites in Example 1.

[0205] The coating process of Example 1 and Comparative Example 1 is as follows Figure 4 As shown, Figure 4 a is a coating process diagram of the positive electrode material of Example 1, Figure 4 b is a coating process diagram of the positive electrode material of comparative example 1. It can be clearly seen that the material of comparative example 1 has obvious agglomeration on the surface during the coating process, which affects the further processing of the positive electrode sheet and further deteriorates the electrochemical performance.

[0206] The lithium-nickel mixing degree test data of Example 1 and Comparative Example 1 are shown in Table 2. It can be seen that compared with Comparative Example 1, the lithium-nickel mixing degree of the positive electrode material of Example 1 is significantly reduced, and the lithium layer spacing is increased, which is beneficial to the improvement of electrochemical performance.

[0207] The materials of Example 1 are as follows Figure 5 As shown, Figure 5 a is the TEM image of the material, Figure 5 b is the SEM image of the material, from which it can be clearly seen that nucleation sites with particle sizes of 2nm to 5nm are evenly distributed on the surface and inside of the material.

[0208] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A positive electrode material, characterized in that The general chemical formula of the positive electrode material is: Li a Ni x Co y Mr 1-x-y O2(Ⅰ) In formula (I), 0.95≤a<1.05, 0.8≤x<0.95, 0.05≤y≤0.2; the positive electrode material further comprises at least one element selected from Al, Pb, B, P, Ti, V, Mg and Zr; The positive electrode material includes primary particles, and nucleation sites are distributed inside and on the surface of the primary particles; wherein, on the surface of the primary particle, the nucleation sites include nanoparticles containing at least one element of Al, Pb, B, P, Ti, V, Mg and Zr; Nucleation sites with a median particle size of 2nm to 5nm are distributed on the surface of the positive electrode material, and the nucleation sites on the surface of the positive electrode material are in a granular structure.

2. The positive electrode material according to claim 1, characterized in that The positive electrode material further comprises at least one of the following features (1) to (6): (1) The nucleation sites include at least one of metal oxides and non-metal oxides; (2) The nucleation sites include at least one of metal oxides and non-metal oxides, and the nucleation sites include at least one of Al2O3, PbO2, B2O3, P2O5, TiO2, V2O5, MgO and ZrO2; (3) Crystalline ions are also distributed inside the primary particles; (4) Crystallization ions are further distributed inside the primary particles, and the crystallization ions include at least one of aluminum ions, titanium ions, boron ions, and carbon ions; (5) The positive electrode material includes secondary particles, and the secondary particles include a plurality of the primary particles; (6) The positive electrode material includes secondary particles, and the secondary particles include a plurality of stacked primary particles.

3. The positive electrode material according to claim 1, characterized in that The positive electrode material further comprises at least one of the following features (1) to (3): (1) The content of residual hydroxide in the positive electrode material is less than or equal to 0.2wt%; (2) The content of residual carbonate in the positive electrode material is less than or equal to 0.2 wt%; (3) In the XRD test of the positive electrode material, the Bragg diffraction peak intensity ratio R of the (003) crystal plane and the (104) crystal plane of the positive electrode material, wherein, And 1.3≤R≤1.

6.

4. The positive electrode material according to claim 1, characterized in that The positive electrode material includes at least one of the following features (1) to (5); (1) The ionic conductivity of the positive electrode material is greater than or equal to 1.12·10 -9 cm 2 / s; (2) The particle strength of the positive electrode material is greater than or equal to 35 MPa; (3) The median particle size of the positive electrode material is 3 μm to 4.5 μm; (4) The specific surface area of ​​the positive electrode material is 0.4 m 2 / g ~0.5 m 2 / g; (5) The mass concentration of water in the positive electrode material is less than or equal to 400 ppm.

5. A method for preparing the positive electrode material according to any one of claims 1 to 4, characterized in that: The steps include: A mixture containing a lithium source, a nickel source, a cobalt source, a manganese source and an M compound is mixed with a surfactant to obtain a first precursor, wherein the M element in the M compound includes at least one of Al, Pb, B, P, Ti, V, Mg and Zr, and the median particle size of the M compound is 1 nm to 3 nm; The first precursor is subjected to a spray pyrolysis treatment to obtain a second precursor, wherein the temperature of the spray pyrolysis treatment is 500° C. to 800° C.; heat-treating the second precursor to obtain a positive electrode material; The step of adding additives before mixing the mixture containing lithium source, nickel source, cobalt source, manganese source and M compound with surfactant includes at least one of titanium-boron alloy, titanium-carbon alloy and aluminum-titanium-boron alloy.

6. The preparation method according to claim 5, characterized in that The preparation method includes at least one of the following features (1) to (13): (1) The lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium acetate, lithium oxalate, lithium sulfate, lithium chloride and lithium nitrate; (2) The median particle size of the lithium source is 3 μm to 5 μm; (3) The nickel source includes at least one of nickel carbonate, nickel acetate, nickel oxalate, nickel nitrate, nickel chloride and nickel nitrate; (4) The median particle size of the nickel source is 3 μm to 5 μm; (5) The cobalt source includes at least one of cobalt carbonate, cobalt acetate, cobalt oxalate, cobalt sulfate, cobalt chloride and cobalt nitrate; (6) The median particle size of the cobalt source is 3 μm to 5 μm; (7) The manganese source includes at least one of manganese carbonate, manganese acetate, manganese oxalate, manganese sulfate, manganese chloride and manganese nitrate; (8) The median particle size of the manganese source is 3 μm to 5 μm; (9) The M compound includes at least one of carbonate, acetate, nitrate, hydrochloride, sulfate and hydroxide; (10) The mass ratio of the M compound in the first precursor is 500 ppm to 3000 ppm; (11) The stoichiometric ratio of the lithium source, nickel source and manganese source is Li a Ni x Co y Mn 1-x-y O2, 0.95≦a﹤1.05, 0.8≦x﹤0.95, 0.05≦y≦0.2; (12) The surfactant includes at least one of sodium alginate, polyvinyl pyrrolidone, polyethylene glycol, polyacrylonitrile and chitosan; (13) The mass ratio of the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound to the surfactant is 1: (0.01~0.05).

7. The preparation method according to claim 5, characterized in that The method includes at least one of the following features (1) to (4): (1) The method further includes adding a complexing agent before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant; (2) before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, a complexing agent is added, wherein the complexing agent comprises at least one of phosphate, alcohol amine salt, aminocarboxylate, hydroxycarboxylate, organic phosphate and polyacrylate; (3) Before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, a complexing agent is added, and the mass of the complexing agent is 1% to 5% of the mass of the first precursor; (4) Before the mixture containing the lithium source, nickel source, cobalt source, manganese source and M compound is mixed with the surfactant, the step of adding an additive is included, and the mass of the additive is 0.1% to 0.3% of the mass of the first precursor.

8. The preparation method according to claim 5, characterized in that The method includes at least one of the following features (1) to (3): (1) The solvent for the spray pyrolysis treatment includes at least one of water and ethanol; (2) The solvent for the spray pyrolysis treatment includes at least one of water and ethanol, and the solid content of the first precursor in the solvent is 20% to 70%; (3) The injection rate of the spray pyrolysis treatment is 20 mL / min~80 mL / min.

9. The preparation method according to claim 5, characterized in that The method includes at least one of the following features (1) to (4): (1) The heat treatment atmosphere includes at least one of air and oxygen; (2) The heat treatment temperature is 700°C to 1000°C; (3) The heating rate of the heat treatment is 1°C / min to 5°C / min; (4) The heat treatment holding time is 10h~24h.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the positive electrode material according to any one of claims 1 to 4 or the positive electrode material prepared by the method according to any one of claims 5 to 9.

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