Positive electrode material, method for preparing the same, and secondary battery and electric device including the same

Abstract

The present application provides a positive electrode material, comprising a base material particle of formula (I): Li 1+a [Ni x Co y Mn z M b W c ]O2(I) wherein M comprises one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Al, Ca, Zn and Sr, 0.6

Description

Technical Field

[0001] This application relates to the technical field of lithium batteries, and particularly to a cathode material, a preparation method thereof, a secondary battery including the cathode material, and an electrical device. Background Art

[0002] Lithium-ion batteries have been increasingly favored in the battery industry due to their advantages of light weight, long life, and environmental friendliness. The cathode material of lithium-ion batteries has always been the focus of research and development in the industry. Currently, the mainstream cathode materials of lithium-ion batteries, with their characteristics of high capacity and high energy density, meet the requirements of increasingly high energy density and are more favored. However, such cathode materials have problems such as poor capacity, possible particle cracking and pulverization during cycling, poor cycling performance, high lithium impurity content and easy gas generation, and poor safety performance.

[0003] Therefore, there is a need in the art for a cathode material with good performance that can improve at least one of the above problems. Summary of the Invention

[0004] This application is made in view of the above problems, and its purpose is to provide a cathode material including substrate particles with a chemical composition of formula (I):

[0005] Li 1+a [Ni x Co y Mn z M b W c O2 (I)

[0006] Wherein, M includes one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Al, Ca, Zn, and Sr, 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, 0 < a < 0.2, 0 < b < 0.1, 0 < c < 0.1, and x + y + z + b + c = 1; and W is enriched at the grain boundaries of the substrate particles. The cathode material of this application has good comprehensive performance: high discharge specific capacity, good cycling performance, low lithium impurity content, and less gas generation.

[0007] In any embodiment, formula (I) satisfies one or more of the following conditions (1) to (8):

[0008] (1) M includes one or more of Zr, Al, Mg, and Ti;

[0009] (2) 0.8 ≤ x < 1;

[0010] (3) 0 < a < 0.08;

[0011] (4) 0 < b < 0.018;

[0012] (5)0 <c<0.0013;

[0013] (6) b:c = 0.076 to 384, optionally b:c = 5 to 69, and more preferably b:c = 13 to 69;

[0014] (7) (1+a):(x+y+z)=1.01~1.25, optionally (1+a):(x+y+z)=1.05~1.15;

[0015] (8) The doping weight of element M is greater than or equal to the doping weight of element W. Optionally, the weight ratio of element M to element tungsten (W) is 1:(0.1 to 1), and more preferably 1:(0.1 to 0.5). A cathode material that satisfies one or more of the above conditions has better performance.

[0016] In any embodiment, the W content in the substrate particles, within a 40 nm thickness from the grain boundary, is at least 80% by weight, optionally at least 90% by weight, based on the total weight of W in the substrate particles. Almost all the W doped in the material is concentrated at the grain boundaries, which is beneficial for increasing compaction density and improving various properties.

[0017] In any embodiment, based on the total weight of the substrate particles, the W content in the substrate particles is 100–200,000 ppm, optionally 100–3,000 ppm, and more preferably 500–2,500 ppm. This is beneficial for improving particle integrity and cycle performance, etc.

[0018] In any embodiment, the volumetric particle size distribution radius (D) of the positive electrode material v 90-D v 10) / D v The value of 50 is 1.1 to 1.8, optionally 1.2 to 1.5, and more preferably 1.25 to 1.45. This is beneficial for achieving higher compaction density and increasing capacity, etc.

[0019] In any embodiment, the cathode material further includes a coating layer disposed on the surface of the substrate particles, the coating layer comprising at least one of W, Co, Al, and B elements; optionally, the coating layer comprises at least W and / or B elements; more preferably, the coating layer comprises W, Co, Al, and B elements. This further improves the material's cycle performance, which is beneficial for reducing the content of impure lithium and improving safety performance.

[0020] In any embodiment, the covering layer satisfies one or more of the following conditions (1) to (5):

[0021] (1) The coating layer contains 100 ppm to 2000 ppm, optionally 500 ppm to 1000 ppm of W element, based on the total weight of the substrate particles;

[0022] (2) The coating layer contains 100 ppm to 16000 ppm, optionally 1000 ppm to 13000 ppm of Co element, based on the total weight of the substrate particles;

[0023] (3) The coating layer contains 100 ppm to 3000 ppm, optionally 500 ppm to 2000 ppm of Al element, based on the total weight of the substrate particles;

[0024] (4) The coating layer contains 100 ppm to 2000 ppm, optionally 500 ppm to 1500 ppm of B element, based on the total weight of the substrate particles;

[0025] (5) The coating layer contains W, Co, Al and B elements and the total amount of these four elements is 1000 to 22000 ppm, preferably 1000 to 15000 ppm, based on the total weight of the substrate particles. Coating various elements within such a range is more conducive to improving the performance of the material.

[0026] The second aspect of the present application provides a method for preparing a cathode material, the cathode material comprising substrate particles having a chemical composition of formula (I):

[0027] Li 1+a [Ni x Co y Mn z M b W c O2 (I)

[0028] Wherein, M includes one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Al, Ca, Zn and Sr, 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, 0 < a < 0.2, 0 < b < 0.1, 0 < c < 0.1, x + y + z + b + c = 1; and W is enriched at the grain boundaries of the substrate particles;

[0029] The method includes the following steps:

[0030] - S0: Provide a precursor material with a chemical composition of Ni x Co y Mn z (OH)2, 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, and x + y + z = 1,

[0031] -S1: The precursor material is ground and mixed with the W source compound, and then the Li source compound and the M source compound are added and mixed thoroughly. The mixture is then sintered to obtain the substrate particles. The cathode material prepared by the method of this application has good comprehensive performance: high capacity, good cycle performance, low impurity lithium content, and safety performance.

[0032] In any embodiment, the particle size of the W source compound is 20–500 nm, optionally 50–300 nm; and / or the W source compound includes one or more of WO3, H2WO4, Li2WO4, (NH4)2WO4, MgWO4, and Zr(WO3)2; optionally, it includes one or more of WO3, H2WO4, and Li2WO4; and / or the amount of W added is 100–200,000 ppm, optionally 100–3,000 ppm, more preferably 500–2,500 ppm, based on the total weight of the precursor material. Using the above-mentioned W source compound and its particle size is more conducive to the doping of W into the grain boundaries of the material during high-temperature sintering.

[0033] In any embodiment, the M-source compound includes sulfates, nitrates, chlorides, carbonates, oxides, hydroxides, oxalates, and acetates containing the M element, optionally as oxides of the M element; optionally, the M element is one or more of Zr, Al, Mg, and Ti; optionally, the amount of the M element added is 100–5000 ppm, optionally 500–3000 ppm, based on the total weight of the precursor material. These M-containing compounds are more conducive to uniformly doping the M element into the layered material lattice at high temperatures, and such an addition amount is more beneficial to improving the material's performance.

[0034] In any implementation, step S1 satisfies at least one of the following conditions:

[0035] (1) The weight ratio of M to W is 1:(0.1 to 1), or optionally 1:(0.1 to 0.5);

[0036] (2) The ratio between the molar amount of Li atoms and the total molar amount of Ni, Co and Mn atoms is 1.01 to 1.25, and optionally 1.05 to 1.15.

[0037] This results in a cathode material with high discharge specific capacity and good cycle performance.

[0038] In any embodiment, the grinding and mixing is performed using mechanical grinding or ball milling; optionally, the grinding and mixing is performed in a ball mill, preferably a heated ball mill; optionally, the grinding speed is 500–3000 r / min, preferably 1000–2000 r / min, or 800–1500 r / min; optionally, the grinding and mixing is performed at a temperature of 30–100°C, preferably 40–60°C. Using the above process conditions can promote the uniform mixing and stable adhesion of the W source compound and the precursor material, which is beneficial for W doping enrichment at grain boundaries.

[0039] In any embodiment, the method further includes the step of forming a coating layer on the surface of the substrate particles, which includes:

[0040] -S2: Sintering the substrate particles obtained from S1 with a W-containing compound and / or a Co-containing compound; and / or

[0041] -S3: The substrate particles obtained from S1 or the sinter obtained from S2 are mixed with an Al-containing compound and / or a B-containing compound and then sintered.

[0042] By coating the substrate particles using the above coating steps, the material properties are further improved.

[0043] In any implementation, step S2 satisfies one or more of the following conditions:

[0044] (1) The W-containing compound includes one or more of WO3, H2WO4, Li2WO4, (NH4)2WO4, MgWO4, and Zr(WO3)2;

[0045] (2) The amount of W added is 100–2000 ppm, optionally 500–1000 ppm, based on the total weight of the precursor material. This is beneficial for a more uniform W-containing coating layer and for improving material properties.

[0046] In any implementation, step S2 satisfies one or more of the following conditions:

[0047] (1) The Co-containing compound includes one or more of Co3O4, Co(OH)2, CoO, CoOOH, Co(CH3COO)2, CoC2O4, and CoCO3;

[0048] (2) The amount of Co added is 100 to 16,000 ppm, preferably 1,000 to 13,000 ppm, based on the total weight of the precursor material. This is more conducive to reducing surface lithium impurities and improving cycle performance.

[0049] In any embodiment, in step S3, the Al-containing compound includes one or more of Al₂O₃, Al(OH)₃, Al₂(SO₄)₃, AlCl₃, and Al(NO₃)₃; and / or the amount of Al added is 100–3000 ppm, preferably 500–2000 ppm, based on the total weight of the precursor material. This can further improve the interfacial stability of the material particles, reduce interfacial side reactions, and thus be more conducive to improving the recycling, storage, and safety performance of the material.

[0050] In any embodiment, in step S3, the B-containing compound includes one or more of BCl3, B2(SO4)3, B(NO3)3, BN, B2O3, BF3, BBr3, BI3, H2BO5P, H3BO3, C5H6B(OH)2, C3H9B3O6, (C2H5O)3B, and (C3H7O)3B, and / or the amount of B added is 100–2000 ppm, preferably 500–1500 ppm, based on the total weight of the precursor material. This can further reduce the impure lithium content on the material surface, while increasing the material capacity. Furthermore, it can further improve the interfacial side reactions of the material, enhancing its cycling, storage, and safety performance.

[0051] In any embodiment, the volumetric particle size distribution radius of the precursor material is 1.1 to 1.8, optionally 1.2 to 1.5; and / or the D of the precursor material v The thickness of the cathode material is 5μm to 15μm, optionally 5μm to 10μm. This is beneficial for obtaining cathode materials with a higher compaction density, thereby facilitating the achievement of higher capacity.

[0052] A third aspect of this application provides a secondary battery, comprising the positive electrode material of the first aspect or the positive electrode material obtained by the method of the second aspect.

[0053] A fourth aspect of this application provides an electrical device comprising a secondary battery selected from those described in claim 19.

[0054] The cathode material of this application has good overall performance: high capacity, good cycle performance, low amount of impure lithium and low gas production. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of a secondary battery according to one embodiment of this application.

[0056] Figure 2 yes Figure 1 An exploded view of a secondary battery according to one embodiment of this application is shown.

[0057] Figure 3This is a schematic diagram of a battery module according to one embodiment of this application.

[0058] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0059] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0060] Figure 6 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0061] Explanation of reference numerals in the attached figures:

[0062] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Casing; 52 Electrode assembly; 53 Top cover assembly Detailed Implementation

[0063] The following detailed description, with appropriate reference to the accompanying drawings, discloses the positive electrode material and its preparation method, as well as embodiments of the positive electrode sheet, secondary battery, and electrical device comprising the positive electrode material. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0064] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0065] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0066] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0067] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0068] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0069] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or present) and B is false (or absent); A is false (or absent) while B is true (or present); or both A and B are true (or present).

[0070] Lithium-ion batteries (lithium secondary batteries) are increasingly favored by the battery industry for their advantages of light weight, long life, and environmental friendliness. The positive electrode material of lithium-ion batteries has always been the focus of research and development in the industry as its key material. Currently, the mainstream positive electrode materials of lithium-ion batteries are lithium cobalt oxide, lithium iron phosphate, lithium manganate, and nickel cobalt manganese ternary materials, and emerging materials such as NCA (nickel cobalt aluminum) series and LOL (lithium-rich manganese solid solution) have been added, and have been widely commercialized. Among them, ternary materials, especially NCA materials, with their characteristics of high capacity and high energy density, meet the requirements of increasingly high energy density and are more favored.

[0071] However, the ternary positive electrode materials in the prior art are prone to cracks and pulverization of material particles during the process of lithium deintercalation and intercalation, resulting in poor cycle performance, and the existing materials also have high lithium impurity content, gas production and expansion, so the storage and safety performance are poor.

[0072] In view of the above deficiencies of such materials in the prior art, this application provides a positive electrode material and its preparation method. The positive electrode material of this application has a high capacity, and also has improved material structure stability and particle integrity to enhance long cycle performance, and at the same time has a reduced lithium impurity content and gas production, thereby improving storage and safety performance.

[0073] cathode materials

[0074] In one embodiment of this application, a positive electrode material is proposed, including substrate particles with a chemical composition of formula (I):

[0075] Li 1+a [Ni x Co y Mn z M b W c O2 (I)

[0076] Wherein, M includes one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Al, Ca, Zn, and Sr, 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, 0 < a < 0.2, 0 < b < 0.1, 0 < c < 0.1, x + y + z + b + c = 1; and W is enriched at the grain boundaries of the substrate particles.

[0077] The positive electrode material of the present application has good comprehensive performance: high discharge specific capacity, good cycling performance, low amount of lithium impurities, and less gas generation.

[0078] In the positive electrode material of the present application, element M and tungsten (W) are simultaneously doped, and W is enriched at the grain boundaries in the substrate particles, which makes the material have good lattice structure stability and particle integrity, and thus has ideal comprehensive performance: good discharge specific capacity, improved cycling performance, reduced amount of lithium impurities, higher tap density, and improved safety performance.

[0079] For the doped element M, an element with a relative atomic mass < 150 or a stable valence state > +3 is selected as element M. Such an element M has a small atomic mass and radius, has an appropriate electrostatic repulsive force with W, and has a relatively fast migration speed into the interior of the material during the sintering process, thereby inhibiting the migration of W into the interior of the material and making W more likely to be enriched at the grain boundaries.

[0080] In this article, the "grain boundary" is the boundary between individual primary particles in a secondary particle.

[0081] In this article, fine particle units without agglomeration (e.g., single crystal particles) are called "primary particles", and particles formed after the agglomeration of primary particles are called "secondary particles". In this article, the substrate particles are secondary particles. When observed under a scanning electron microscope, the spherical ones are secondary particles, and the nanosheets that make up the secondary particles are primary particles.

[0082] In this article, element W is enriched at the grain boundaries, that is, element W is doped on the surfaces of individual primary particles in the substrate particles. In some embodiments, element M is uniformly doped in the crystal structure of the substrate particles. In this article, "uniform doping" means being completely uniformly distributed inside the material particles (or in the crystal structure).

[0083] In some embodiments, in formula (I), M is selected from one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Al, Ca, Zn, and Sr.

[0084] In some embodiments, in formula (I), M includes one or more of Zr, Al, Mg, and Ti. Doping with these elements as element M is more helpful for stabilizing the crystal structure of the material, promoting the enrichment of W at the grain boundaries, and thus improving the material performance. Further, in some embodiments, M is selected from one or more of Zr, Al, Mg, and Ti.

[0085] In some embodiments, in formula (I), 0.8 ≤ x < 1 and / or 0 < a < 0.08. In the present application, the coefficients x and a can be conventional, but further controlling these values can help improve the material performance.

[0086] In some embodiments, in formula (I), 0 < b < 0.018 and / or 0 < c < 0.0013. This helps to improve the cycling performance of the material, reduce the amount of lithium impurities and gas generation, and improve the safety performance.

[0087] In some embodiments, in formula (I), 0 < y < 0.1; and / or 0 < z < 0.1. In the present application, the values of the coefficients y and z are conventional and not critical, and they can be within the above ranges.

[0088] In some embodiments, in formula (I), b:c = 0.076 to 384, optionally b:c = 5 to 69, more optionally b:c = 13 to 69. Such a cathode material has better performance.

[0089] In some embodiments, formula (I) satisfies (1 + a):(x + y + z) = 1.01 to 1.25, optionally (1 + a):(x + y + z) = 1.05 to 1.15, and then the performance of the cathode material is better.

[0090] In some embodiments, the doping weight of element M is ≥ the doping weight of element W. Optionally, the weight ratio of element M to element W is 1:(0.1 to 1), more optionally 1:(0.1 to 0.5). When the contents of element M and element W satisfy the above relationship, it is more beneficial for element W to be enriched at the grain boundaries, improve the structural stability and particle integrity of the material, and enhance the migration ability of active ions (such as Li + ) in the material, improve the cycling stability, increase the tap density, reduce the amount of lithium impurities, and improve the safety performance.

[0091] In some embodiments, in the substrate particles, the content of W within a thickness of 40 nm from the grain boundary is at least 80%, optionally at least 90%. In the cathode material of the present application, the doped element W is almost entirely enriched at the grain boundaries, which is beneficial to improving the structural integrity and stability of the material particles, increasing the tap density, and improving the performance.

[0092] In some embodiments, based on the total weight of the substrate particles, the amount of W is 100 to 200000 ppm, optionally 100 to 3000 ppm, more optionally 500 to 2500 ppm. This is beneficial to improving particle integrity and cycling performance, etc., while ensuring that the material has good electrochemical performance.

[0093] In this article, the doping amount of element W refers to the amount of element W in the substrate particles.

[0094] In some embodiments, the amount of M is 100 to 5000 ppm, optionally 500 to 3000 ppm, based on the total weight of the substrate particles. Including M within such a range is more conducive to the enrichment of W at grain boundaries and helps the material achieve desired properties.

[0095] In some embodiments, the volumetric particle size distribution of the cathode material has a diameter (D) v 90-D v 10) / D v The particle size distribution (VPD) of the cathode material is 1.1 to 1.8, optionally 1.2 to 1.5, and more preferably 1.25 to 1.45. The cathode material of this application has a volumetric particle size distribution within the above range, which is more conducive to achieving a higher compaction density (e.g., a compaction density ≥3.45 g / cc, or even ≥3.50 g / cc, under 5 tons of pressure), thereby improving energy density and specific capacity.

[0096] In this paper, "volume particle size distribution radius" is defined as (D v 90-D v 10) / D v The value of 50, where D v 90. D v 10 and D v 50 represents the average particle size corresponding to 90%, 10%, and 50% of the particles in the volumetric distribution, respectively. The particle size distribution spacing reflects the width of the particle size distribution—the larger the spacing, the wider the particle size distribution. D v 90. D v 10 and D v 50 can be measured using conventional methods and instruments in the art (e.g., using a laser particle size analyzer).

[0097] This paper uses the parameter "compacted density" to quantitatively evaluate the hardness of cathode material particles and the compacted density of cathode sheets. Compacted density can be tested using any suitable method known to those skilled in the art. In this paper, a certain mass m of cathode material is placed in a cylindrical mold with an inner radius R. Different pressures are applied using a press to test the particle size distribution under different pressures until a bimodal distribution appears at a certain pressure (indicating the presence of a large number of compressed particles in the tested material). The density at that pressure is then termed the compacted density. A higher compacted density value indicates a higher volumetric energy density of the material particles. The compacted density is calculated using the following formula:

[0098] Compacted density = m / (π·R) 2 ·ΔH)

[0099] Where m is the mass of the material being tested added to the mold, R is the inner radius of the mold, and ΔH is the height difference before and after pressure is applied.

[0100] In some embodiments, the cathode material of this application further includes a coating layer disposed on the surface of the substrate particles, the coating layer comprising at least one of W, Co, Al, and B elements. The cathode material comprising a coating layer containing at least one of the above elements can effectively reduce surface lithium content and / or suppress interfacial side reactions, further improving at least one of the capacity, cycle performance, and safety performance of the cathode material.

[0101] In this document, "mixed lithium" has the meaning commonly understood by those skilled in the art, referring to lithium source compounds or their byproducts that did not fully react during the high-temperature sintering process of a material. Its accumulation on the material surface not only increases the migration resistance of active ions, leading to a decrease in capacity, but may also generate gases (such as CO2), increasing safety risks. Generally, mixed lithium includes (but is not limited to) lithium carbonate and / or lithium hydroxide. The content of mixed lithium can be determined using any method known to those skilled in the art, such as acid-base titration.

[0102] In some embodiments, the coating layer comprises W and / or B elements; this is more beneficial for improving the material's capacity and cycling performance. In some embodiments, the coating layer comprises W, Co, Al, and B elements. This further improves the material's capacity and cycling performance, and helps reduce the content of impure lithium and improve safety performance. The W and / or Co coating layer can optimize the enrichment of W at grain boundaries, reduce surface impure lithium, improve interface stability, and improve cycling performance; the B and / or Al coating layer helps to increase the material's specific capacity, mitigate interfacial side reactions, and facilitate the material's cycling performance.

[0103] In some embodiments, the coating layer contains 100 ppm to 2000 ppm, optionally 500 ppm to 1000 ppm of W element, based on the total weight of the substrate particles. In some embodiments, the coating layer contains 100 ppm to 16000 ppm, optionally 1000 ppm to 13000 ppm of Co element, based on the total weight of the substrate particles. In some embodiments, the coating layer contains 100 ppm to 3000 ppm, optionally 500 ppm to 2000 ppm of Al element, based on the total weight of the substrate particles. In some embodiments, the coating layer contains 100 ppm to 2000 ppm, optionally 500 ppm to 1500 ppm of B element, based on the total weight of the substrate particles. Coating various elements within such a range is more beneficial for improving the material's properties.

[0104] In some embodiments, the coating layer contains W, Co, Al and B elements, and the total amount of these four elements is 1,000 to 22,000 ppm, preferably 1,000 to 15,000 ppm, based on the total weight of the substrate particles.

[0105] The presence and thickness of the coating layer can be confirmed by conventional methods and instruments. For example, it can be observed through a scanning electron microscope, a transmission electron microscope, etc. In the microscope field of view, the coating layer can be seen as an independent layer outside the substrate particles. The content of various elements in the coating layer can also be determined by conventional methods and instruments. For example, it can be quantitatively obtained by using the EDS element distribution test of a scanning electron microscope.

[0106] In some embodiments, the coating layer has a conventional thickness range in the art; optionally, the thickness of the coating layer is 0.001 μm to 1 μm, and optionally 0.01 μm to 0.5 μm. When the thickness of the coating layer is within the above range, it is more beneficial for the cathode material to have better electrochemical performance and volumetric energy density.

[0107] Preparation method

[0108] Another aspect of the present invention provides a method for preparing the cathode material of formula (I),

[0109] Li 1+a [Ni x Co y Mn z M b W c O2 (I)

[0110] where M includes one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Al, Ca, Zn, and Sr, 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, 0 < a < 0.2, 0 < b < 0.1, 0 < c < 0.1, and x + y + z + b + c = 1; and W is enriched at the grain boundaries of the substrate particles;

[0111] The method includes the following steps:

[0112] - S0: Provide a precursor material with a chemical composition of Ni x Co y Mn z (OH)2, 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, and x + y + z = 1;

[0113] - S1: Grind and mix the precursor material with a W-source compound, then add a Li-source compound and a M-source compound thereto and mix well, and sinter the mixture to obtain the substrate particles. The cathode material prepared by the method of the present application has good comprehensive properties: high capacity, good cycle performance, low amount of impurity lithium, and safety performance.

[0114] In some embodiments, in formula (I), M is selected from one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Al, Ca, Zn, and Sr. In some embodiments, the particle size of the W source compound is 20–500 nm, optionally 50–300 nm. In the method of this application, using a W source compound with the above-mentioned particle size range makes it easier for W to be doped into the grain boundaries of the material during sintering.

[0115] In some embodiments, the W source compound includes one or more of WO3, H2WO4, Li2WO4, (NH4)2WO4, MgWO4, and Zr(WO3)2; optionally, it includes one or more of WO3, H2WO4, and Li2WO4. These W source compounds more readily promote W doping at the grain boundaries of the material during high-temperature sintering. Further, in some embodiments, the W source compound is selected from one or more of WO3, H2WO4, Li2WO4, (NH4)2WO4, MgWO4, and Zr(WO3)2; optionally, it is selected from one or more of WO3, H2WO4, and Li2WO4.

[0116] In some embodiments, the amount of W added is 100–3000 ppm, optionally 500–2500 ppm, based on the total weight of the substrate particles. The addition of W within this range is beneficial for improving the structural stability of the material, enhancing cycle performance, and achieving a higher specific capacity.

[0117] In some embodiments, the M-source compound includes sulfates, nitrates, chlorides, carbonates, oxides, hydroxides, oxalates, and acetates of element M, and optionally includes oxides of element M. Further, in some embodiments, the M-source compound is selected from sulfates, nitrates, chlorides, carbonates, oxides, hydroxides, oxalates, and acetates of element M, and optionally is an oxide of element M. In some embodiments, element M includes one or more of Zr, Al, Mg, and Ti. These compounds containing element M are more advantageous for uniformly doping element M into the layered material lattice at high temperatures and achieving structural stability of the material. Further, in some embodiments, element M is one or more of Zr, Al, Mg, and Ti.

[0118] In some embodiments, the amount of element M added is 100–5000 ppm, optionally 500–3000 ppm, based on the total weight of the substrate particles. This can improve the cycle stability and specific capacity of the cathode material.

[0119] In some embodiments, step S1 satisfies the ratio of M to W elements being 1:(0.1 to 1), optionally 1:(0.1 to 0.5). This results in a cathode material with better performance.

[0120] In some embodiments, the ratio of the molar amount of Li atoms to the total molar amount of Ni, Co, and Mn atoms in step S1 is 1.01 to 1.25, optionally 1.05 to 1.15. This results in a cathode material with high discharge specific capacity and good cycle performance (e.g., the material is less prone to irreversible phase transitions during cycling).

[0121] In this article, for the sake of simplicity, Me can be used to represent the total molar amount of Ni, Co, and Mn. The ratio between the molar amount of Li atoms and the total molar amount of Ni, Co, and Mn atoms can be expressed as "Li / Me".

[0122] The lithium source compound can be any conventional lithium source compound known to those skilled in the art. In some embodiments, the lithium source compound includes one or more of LiOH·H2O, Li2CO3, Li2SO4, LiNO3, LiC2O4, and CH3COOLi. Using the above-mentioned lithium source compound can help the cathode material to have a stable layered structure and ensure high electrochemical performance. Further, in some embodiments, the lithium source compound is selected from one or more of LiOH·H2O, Li2CO3, Li2SO4, LiNO3, LiC2O4, and CH3COOLi.

[0123] In some embodiments, the grinding and mixing is performed using mechanical milling or ball milling. In some embodiments, the grinding and mixing is performed in a ball mill, optionally a heated ball mill. In some embodiments, the ball mill speed is optionally 500–3000 r / min, optionally 1000–2000 r / min. In some embodiments, the grinding and mixing is performed at a temperature of 30–100°C, optionally 40–60°C. Using the above process conditions can promote the uniform mixing and stable adhesion of the W source compound and the precursor material, which is beneficial for W doping enrichment at grain boundaries.

[0124] In some embodiments, the sintering in step S1 is performed at a temperature of 650–950°C. In some embodiments, the sintering is performed for 10–20 hours. In some embodiments, the sintering is performed in air or an O2 atmosphere. Using the above process conditions, the desired cathode material can be obtained.

[0125] In some embodiments, the method of this application further includes the step of forming a coating layer on the surface of the substrate particles, which includes:

[0126] -S2: Sintering the substrate particles obtained from S1 with a W-containing compound and / or a Co-containing compound; and / or

[0127] -S3: The substrate particles obtained from S1 or the sinter obtained from S2 are mixed with an Al-containing compound and / or a B-containing compound and then sintered.

[0128] By coating the substrate particles using the above-described coating steps, the material properties are further improved. In the method of this application, the coating of different elements is carried out in separate steps. This is not only based on the sintering temperature requirements for achieving the best coating effect for different elements, but also to ensure that different elements are positioned in the coating layer in a manner more conducive to improving material properties. Compared to Al and / or B, the coating of W and / or Co is carried out first. That is, it is preferable that the coating containing W and / or Co is carried out directly on the surface of the substrate particles. In this way, the W element in the coating layer can supplement the insufficient W doping at the grain boundaries in step S1, thereby helping to improve the integrity and cycling performance of the particles. Co can reduce the impurity lithium content on the surface of the substrate particles, improve interface stability, and improve cycling performance. Coating the substrate particles with Al and / or B elements, whether coated or uncoated, is beneficial to reducing interfacial side reactions between the material and the electrolyte, increasing capacity, and improving the material's cycling performance.

[0129] In some embodiments, in step S2, the W-containing compound has a conventional particle size; optionally, the particle size of the W-containing compound is 0.01–5 μm, more preferably 0.05–1 μm, and even more preferably 0.1–1 μm. Using W-containing compound materials with such a particle size range allows for more uniform coating.

[0130] In some embodiments, in step S2, the substrate particles obtained from S1 are sintered after being mixed with at least a W-containing compound. In some embodiments, in step S2, the W-containing compound includes one or more of WO3, H2WO4, Li2WO4, (NH4)2WO4, MgWO4, and Zr(WO3)2. In some embodiments, in step S2, the W-containing compound is selected from one or more of WO3, H2WO4, Li2WO4, (NH4)2WO4, MgWO4, and Zr(WO3)2. Selecting these W-containing compounds is more conducive to forming a stable coating layer, avoiding direct contact between the electrolyte and the substrate particles, and suppressing interfacial side reactions.

[0131] In some embodiments, in step S2, the amount of W added is 100 to 2000 ppm, optionally 100 to 1000 ppm, based on the total weight of the precursor material. Adding W within this range is more beneficial for improving the material's cycling performance.

[0132] In some embodiments, in step S2, the Co-containing compound includes one or more of Co3O4, Co(OH)2, CoO, CoOOH, Co(CH3COO)2, CoC2O4, and CoCO3. In some embodiments, the Co-containing compound is selected from one or more of Co3O4, Co(OH)2, CoO, CoOOH, Co(CH3COO)2, CoC2O4, and CoCO3. The aforementioned Co-containing compounds are more beneficial for reducing surface lithium impurities and improving cycle performance.

[0133] In some embodiments, in step S2, the Co-containing compound has a conventional particle size; optionally, the Co-containing compound has a particle size of 0.01–10 μm, and optionally exists in the form of particles of 0.1–1 μm. The addition of a Co-containing compound within this particle size range results in better coating, which is more conducive to reducing the amount of impure lithium and improving the cycling performance of the material.

[0134] In some embodiments, in step S2, the amount of Co in the coating layer is 100–16000 ppm, preferably 1000–13000 ppm, based on the total weight of the cathode material. Using this amount of Co coating helps reduce impurities on the surface of the substrate particles and improves the cycle performance of the cathode material.

[0135] In some embodiments, in step S2, the sintering is performed at a temperature of 500–800°C, preferably 550–750°C. In some embodiments, the sintering is carried out for 5–15 hours, preferably 5–10 hours. In some embodiments, the sintering is performed in air or an O2 atmosphere. Using a sintering process is beneficial for partially removing W from the W-containing compound. 6+ Further doping into the grain boundaries of the cathode material substrate particles; at the same time, it also helps to coat the surface of the cathode material substrate particles with Co-containing compounds and interact with the impure lithium, thereby improving the material properties.

[0136] In some embodiments, in step S3, the B-containing compound includes one or more of BCl3, B2(SO4)3, B(NO3)3, BN, B2O3, BF3, BBr3, BI3, H2BO5P, H3BO3, C5H6B(OH)2, C3H9B3O6, (C2H5O)3B, and (C3H7O)3B. In some embodiments, the B-containing compound is selected from one or more of BCl3, B2(SO4)3, B(NO3)3, BN, B2O3, BF3, BBr3, BI3, H2BO5P, H3BO3, C5H6B(OH)2, C3H9B3O6, (C2H5O)3B, and (C3H7O)3B. In some embodiments, in step S3, the coating amount of B, based on the total weight of the cathode material, is 100–2000 ppm, preferably 500–1500 ppm. Coating with a B-containing compound can further reduce the impure lithium content on the material surface, while increasing the material's capacity. In addition, it can further improve the interfacial side reactions of the material, and enhance the material's cycle life, storage, and safety performance.

[0137] In some embodiments, in step S3, the substrate particles obtained from S1 or the product obtained from S2 are sintered after being mixed with at least the compound containing B.

[0138] In some embodiments, in step S3, the Al-containing compound includes one or more of Al₂O₃, Al(OH)₃, Al₂(SO₄)₃, AlCl₃, and Al(NO₃)₃. In some embodiments, the Al-containing compound is selected from one or more of Al₂O₃, Al(OH)₃, Al₂(SO₄)₃, AlCl₃, and Al(NO₃)₃. In some embodiments, in step S3, based on the total weight of the cathode material, the Al coating amount is 100–3000 ppm, preferably 500–2000 ppm. Coating with an Al-containing compound can further improve the interfacial stability of the material particles and reduce interfacial side reactions, thereby better improving the material's cycleability, storage, and safety performance.

[0139] In some embodiments, in step S3, the sintering is performed at a temperature of 200–500°C, optionally 200–400°C. In some embodiments, the sintering is performed for 5–15 hours, optionally 5–10 hours. In some embodiments, the sintering is performed in air or an O2 atmosphere. The sintering process of this invention facilitates the coating of B compounds and / or Al compounds onto the surface of the cathode material substrate particles, achieving a good coating effect.

[0140] In some embodiments, the precursor material is in particulate form, and the volumetric particle size distribution has a diameter of 1.1–1.8, optionally 1.2–1.5. In some embodiments, the precursor material has a D... v The particle size of the precursor material is 5μm to 15μm, optionally 5μm to 10μm. Using such precursor material particles is beneficial for obtaining cathode materials with a higher compaction density, thereby facilitating the achievement of higher capacity.

[0141] In some embodiments, the mixing in step S2 or step S3 can be carried out in suitable equipment known to those skilled in the art, such as a plow mixer, a high-speed mixer, or an inclined mixer.

[0142] Another aspect of this application provides a cathode material obtained according to the above method.

[0143] Secondary batteries and electrical appliances

[0144] Another aspect of this application provides a secondary battery, including the positive electrode material of this application, the positive electrode material obtained by the method of this application, or the positive electrode sheet of this application.

[0145] Secondary batteries include single-cell battery, battery module battery, and battery pack battery.

[0146] Another aspect of this application provides an electrical device, including the secondary battery of this application.

[0147] In addition, the battery cell, battery module, battery pack and power device of this application will be described below with appropriate reference to the accompanying drawings.

[0148] In one embodiment of this application, a secondary battery is provided.

[0149] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0150] [Positive electrode plate]

[0151] Another aspect of this application provides a positive electrode sheet, including the positive electrode material of this application or the positive electrode material obtained by the method of this application.

[0152] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including the positive electrode material of this application.

[0153] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0154] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0155] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0156] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0157] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive electrode material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0158] [Negative electrode plate]

[0159] The negative electrode includes a negative current collector and a negative electrode film layer optionally disposed on at least one surface of the negative current collector. The negative electrode film layer includes a negative electrode active material.

[0160] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0161] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0162] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0163] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0164] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0165] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0166] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0167] [Electrolytes]

[0168] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0169] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0170] In some embodiments, the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0171] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0172] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0173] [Isolation membrane]

[0174] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0175] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. In some embodiments, the separator may also have one or more coatings.

[0176] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0177] [Outer Packaging]

[0178] In some embodiments, the secondary battery may include an outer packaging for encapsulating the positive electrode, negative electrode, and electrolyte. As an example, the positive electrode, negative electrode, and separator may be stacked or wound to form a stacked or wound battery cell, with the cell encapsulated within the outer packaging; the electrolyte is the electrolyte described in the first aspect of this application, and the electrolyte is immersed in the battery cell. The number of cells in the secondary battery may be one or more, which can be adjusted according to requirements.

[0179] In one embodiment, this application provides an electrode assembly. In some embodiments, the positive electrode, negative electrode, and separator are fabricated into the electrode assembly using a winding process or a stacking process. An outer packaging can be used to encapsulate the aforementioned electrode assembly and electrolyte.

[0180] In some embodiments, the outer packaging of the secondary battery can be a soft pack, such as a pouch. The material of the soft pack can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS). In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 The example shown is a square-structured battery cell 5.

[0181] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0182] In some implementations, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0183] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0184] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0185] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0186] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0187] In addition, this application also provides an electrical device, which includes the secondary battery provided in this application. The secondary battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0188] As the electrical device, a single battery cell, a battery module, or a battery pack can be selected according to its usage requirements.

[0189] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0190] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0191] Example

[0192] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0193] Example 1

[0194] 1. Preparation of cathode materials

[0195] -S0: Provides precursor material Ni 0.9 Co 0.05 Mn 0.05 (OH)2, D v 50 is 8.5μm, (D v90 -D v10 ) / D v50 It is 1.35.

[0196] -S1: WO3 (particle size 50 nm) and the precursor material were ball-milled in a heated ball mill (2000 r / min, 60 °C) to obtain a mixture, wherein the amount of W added was 500 ppm (based on the total weight of the precursor material). LiOH·H2O, Al2O3, and the above mixture were mixed to achieve a Li / Me molar ratio of 1.15, and the amount of Al added was 500 ppm (based on the total weight of the precursor material). The weight ratio of M (Al) to W was 1:1. The mixture was then sintered at 750 °C for 20 h in an O2 atmosphere to obtain the substrate particles.

[0197] 2. Preparation of the positive electrode sheet

[0198] The prepared positive electrode material, polyvinylidene fluoride (PVDF), and conductive carbon (Super P) were added to methylpyrrolidone (NMP) in a weight ratio of 90:5:5. The mixture was stirred in a drying room to prepare a positive electrode slurry (solid content of 97.44%). The slurry was then spread on aluminum foil at a concentration of 176 mg / cm³. 2 The positive electrode slurry is coated with a loading amount and then dried and cold-pressed to form a positive electrode sheet.

[0199] 3. Preparation of negative electrode sheet

[0200] Artificial graphite (anode active material), hard carbon, acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC) (thickener) were thoroughly mixed in a deionized water solvent system at a weight ratio of 90:5:2:2:1 to obtain a cathode slurry with a solid content of 96.5%. This slurry was then subjected to a concentration of 124 mg / cm³. 2The loading amount is coated onto copper foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0201] 4. Separating membrane

[0202] Commercially available polyethylene (PE) diaphragm.

[0203] 5. Preparation of electrolyte

[0204] Lithium hexafluorophosphate (LiPF6) was added to a mixed solvent of dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylene carbonate (EC) in a volume ratio of 1:1:1 and dissolved thoroughly to obtain a usable electrolyte (lithium salt concentration of 1 mol / L).

[0205] 6. Preparation of batteries (full cells)

[0206] The obtained positive electrode (20.8cm) 2 ), separating membrane (22.4cm) 2 ), negative electrode plate (22.2cm) 2 Stack the cells in sequence, ensuring the separator is positioned between the positive and negative electrodes for isolation, and then wind them to obtain the bare cell. Place the bare cell in an outer package, inject 0.5g of electrolyte, and seal to obtain a full battery.

[0207] 7. Fabrication of coin cells:

[0208] The positive electrode sheet (1.54 cm) prepared in item 2 above is used. 2 A coin cell is assembled in a coin cell box using lithium foil as the negative electrode, a separator, and the aforementioned electrolyte.

[0209] II. Performance Testing

[0210] 1. Characterization of the chemical composition of the substrate particles:

[0211] A certain mass of powder was taken, digested with HF, and added to an ICP-OES instrument to detect the content of Li, Ni, Co, Mn, W and M elements, so as to obtain the specific molar ratio of the element content and the specific chemical composition (as shown in Table 1).

[0212] 2. Detection method for W enrichment sites in grain boundaries:

[0213] The substrate particles were cut into sections using focused ion beam sputtering. The cross-sections were then observed under a scanning electron microscope in conventional mode, and the selected particle cross-sections were randomly selected. The selected positions were then fixed, and the scanning electron microscope voltage was adjusted to 15 kV. Under this voltage, EDS elemental distribution showed that W elements were concentrated at the grain boundaries of the substrate particles.

[0214] The W content variation from the grain boundary to the interior of a primary particle was measured using EDS elemental line distribution. For the substrate particles of Example 1, a decreasing trend of W content was observed from the grain boundary to the interior of the primary particle: within the primary particle, the W content was 84% ​​within a 40 nm range from the grain boundary, based on the total weight of W in the substrate particles.

[0215] 3. Verification of uniform doping of element M in material particles:

[0216] The substrate particles were cut into sections using methods such as focused ion beam sputtering or metallographic sample preparation, and the internal cross-sectional morphology of the particles was observed under a scanning electron microscope in conventional mode. EDS elemental distribution analysis revealed that the nitrogen element was uniformly distributed across the cross-section of the substrate particles.

[0217] 4. Material compaction density test method

[0218] 2g of positive electrode material was placed in a cylindrical mold with an inner radius of 8mm. Different pressures were applied to the material in the mold using a press until a bimodal particle size distribution appeared at a certain pressure. The compaction density was calculated using the following formula:

[0219] Compacted density = m / (π·R) 2 ·ΔH)

[0220] Where m is the mass of the material being tested added to the mold, R is the inner radius of the mold, and ΔH is the height difference of the material before and after pressure is applied.

[0221] 5. Initial capacitance test method for coin cells:

[0222] Under a constant temperature environment of 25℃, charge at 0.1C to 4.3V, then charge at 4.3V with constant voltage until the current is ≤0.05mA, let stand for 2 minutes, and record the charging capacity at this time as C0. Then discharge at 0.1C to 2.8V, and the discharge capacity at this time is the initial capacity.

[0223] 6. Initial capacitance test method:

[0224] Under a constant temperature environment of 25℃, the newly made full battery is left to stand for 5 minutes, discharged at 1 / 3C to 2.8V, left to stand for 5 minutes, charged at 1 / 3C to 4.25V, and then charged at a constant voltage of 4.25V until the current is ≤0.05mA. After standing for 5 minutes, it is discharged at 1 / 3C to 2.8V. The discharge capacity at this time is the initial specific capacity.

[0225] 7. All-electric 25 / 45℃ cycle performance test:

[0226] Under a constant temperature environment of 25℃, the voltage was charged at 1C to 4.25V, then charged at 4.25V at a constant voltage until the current ≤0.05mA. After resting for 5 minutes, the voltage was discharged at 1C to 2.8V, which constitutes one cycle. The discharge capacity was recorded as D1. After 150 cycles, the discharge capacity D was measured. 150 Calculate the capacity retention rate using the following formula:

[0227] Capacity retention rate = (D 150 / D1)×100%, and record it in Table 1.

[0228] Under a constant temperature environment of 45℃, the above steps were followed to conduct the test and the capacity retention rate was calculated and recorded in Table 1.

[0229] 8. Lithium content test:

[0230] The impure lithium content of the material was determined by acid-base titration. 30g of sample was placed in 100ml of pure water, stirred for 30min, allowed to stand for 5min, filtered, and 10ml of the supernatant was titrated with 0.05mol / L hydrochloric acid standard solution. The pH electrode was used as the indicator electrode, and the endpoint was determined by the abrupt change in potential. The impure lithium content of the cathode material was then calculated.

[0231] 9. Gas saturation test of the entire battery:

[0232] Fully charged battery cells at 100% state of charge (SOC) were stored at 70°C for 30 days. The volume of the cells before and after storage was measured using the water displacement method. The specific steps are as follows:

[0233] The battery cell under test is left to stand and cool to room temperature. The weight of the battery cell is measured using a balance, and the reading is F1. Then, the battery cell is completely immersed in deionized water (density known to be 1 g / cm³). 3 In this case, if the balance reading is F2, then the buoyant force F on the battery cell is... 浮 =F1-F2; then according to Archimedes' principle F 浮 =ρgV 排 Calculate V 排 = (F1-F2) / ρg, which is the volume of the battery cell at this time.

[0234] The increase in cell volume after storage relative to cell volume before storage is the gas production rate; the ratio of gas production rate to cell capacity (the cell design capacity is 4Ah) is the gas production rate per unit capacity (mL / Ah), as shown in Table 2 below.

[0235] Example 2

[0236] Example 2 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 100 nm and the Li / Me molar ratio is modified to 1.1.

[0237] Example 3

[0238] Example 3 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 56 nm and the Li / Me molar ratio is modified to 1.05.

[0239] Example 4

[0240] Example 4 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 68 nm and the Li / Me molar ratio is modified to 1.2:1.

[0241] Example 5

[0242] Example 5 is basically the same as Example 1, except that the precursor in step S0 is composed of Ni. 0.64 Co 0.35 Mn 0.01 (OH)2, the particle size of the W source compound in step S1 is 77 nm.

[0243] Example 6

[0244] Example 6 is basically the same as Example 1, except that the precursor in step S0 is composed of Ni. 0.64 Co 0.01 Mn 0.35 The particle size of the W source compound in step (OH)2, S1 is 105 nm.

[0245] Example 7

[0246] Example 7 is basically the same as Example 1, except that the precursor in step S0 is composed of Ni. 0.8 Co 0.1 Mn 0.1 The particle size of the W source compound in step (OH)2, S1 is 89 nm.

[0247] Example 8

[0248] Example 8 is basically the same as Example 1, except that the precursor in step S0 is composed of Ni. 0.95 Co 0.025 Mn 0.025 The W source compound in step (OH)2,S1 has a particle size of 95 nm.

[0249] Example 9

[0250] Example 9 is basically the same as Example 1, except that the amount of Al added in step S1 is 29,000 ppm, the amount of W added is 900 ppm, and the particle size of the W source compound is 120 nm.

[0251] Example 10

[0252] Example 10 is basically the same as Example 1, except that the amount of Al added in step S1 is 15000 ppm, the amount of W added is 900 ppm, and the particle size of the W source compound is 85 nm.

[0253] Example 11

[0254] Example 11 is basically the same as Example 1, except that the amount of Al added in step S1 is 5500 ppm, the amount of W added is 19000 ppm, and the particle size of the W source compound is 90 nm.

[0255] Example 12

[0256] Example 12 is basically the same as Example 1, except that the amount of Al added in step S1 is 5500 ppm, the amount of W added is 89000 ppm, and the particle size of the W source compound is 110 nm.

[0257] Example 13

[0258] Example 13 is basically the same as Example 1, except that the amount of Al added in step S1 is 5500 ppm, the amount of W added is 155000 ppm, and the particle size of the W source compound is 90 nm.

[0259] Example 14

[0260] Example 14 is basically the same as Example 1, except that the Dv50 of the precursor in step S0 is 9.5, (D v90 -D v10 ) / D v50 The ratio of W to W in step S1 is 1.5; the W source compound in step S1 is replaced with H2WO4 (particle size 94nm), and the amount of W added is 1000ppm, based on the total weight of the precursor materials; the M source compound is ZrO2, and the weight ratio of M to W is 1:0.33.

[0261] Example 15

[0262] Example 15 is basically the same as Example 1, except that the Dv50 of the precursor in step S0 is 9, (D v90 -D v10 ) / D v50 The ratio is 1.2; in step S1, the W source compound is replaced with Li2WO4 (particle size 68nm), and the amount of W added is 1500ppm, based on the total weight of the precursor materials; the M source compound is TiO2, and the weight ratio of M to W is 1:0.3.

[0263] Example 16

[0264] Example 16 is basically the same as Example 1, except that: the W source compound in step S1 is replaced with Li2WO4 (particle size 72nm), the amount of W added is 1500ppm, based on the total weight of the precursor materials; the M source compound is MgO, and the weight ratio of M to W is 1:1.

[0265] Example 17

[0266] Example 17 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 78 nm, the amount of Al added is 100 ppm, and the amount of W added is 100 ppm, based on the total weight of the precursor materials.

[0267] Example 18

[0268] Example 18 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 90 nm, the amount of Al added is 2000 ppm, and the amount of W added is 2000 ppm, based on the total weight of the precursor materials.

[0269] Example 19

[0270] Example 19 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 60 nm, the amount of Al added is 1000 ppm, and the amount of W added is 1000 ppm, based on the total weight of the precursor materials.

[0271] Example 20

[0272] Example 20 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 120 nm, the amount of Al added is 5000 ppm, and the amount of W added is 1000 ppm, based on the total weight of the precursor materials.

[0273] Example 21

[0274] Example 21 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 150 nm, the amount of Al added is 5000 ppm, and the amount of W added is 500 ppm, based on the total weight of the precursor materials.

[0275] Example 22

[0276] Example 22 is basically the same as Example 1, except that the particle size of the W source compound in step S1 is 80 nm, the amount of Al added is 5000 ppm, and the amount of W added is 2500 ppm, based on the total weight of the precursor materials.

[0277] Comparative Example 1

[0278] Comparative Example 1 uses a cathode material from existing technologies, with a chemical composition of LiNi. 0.9 Co 0.05 Mn 0.05 O2, the remaining steps are the same as in Example 1.

[0279] Table 1 shows the relevant parameters of the substrate particles prepared in Examples 1-12:

[0280] Table 1

[0281]

[0282]

[0283] *The weight percentage (wt.%) of W within a 40 nm thickness from the grain boundary in a primary particle, based on the total weight of W doped in the substrate particles.

[0284] **Based on the total weight of the substrate particles.

[0285] ***Volume particle size distribution radius = (D v 90-D v 10) / D v 50.

[0286] Table 2 shows the performance test results of the cathode materials in Examples 1-22:

[0287] Table 2

[0288]

[0289]

[0290] As can be seen from Tables 1-2, compared with the comparative examples, the cathode material of the present invention has higher compaction density, higher capacity and better cycle performance (high capacity retention over a wide temperature range), and lower amount of impurities and less gas production, making it safer.

[0291] Example 23

[0292] Example 23 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, the following step S2 is performed:

[0293] S2: The substrate particles obtained in S1 are mixed with H2WO4 (particle size 0.05μm) to a W content of 2000ppm (based on the total weight of the substrate particles). The mixture is sintered at 700℃ for 15h in an O2 atmosphere to obtain a cathode material with a W-coated layer.

[0294] Example 24

[0295] Example 24 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, the following step S2 is performed:

[0296] S2: The substrate particles obtained in S1 are mixed with CoO (particle size 0.1 μm) to a Co addition amount of 16000 ppm (based on the total weight of the substrate particles). The mixture is sintered at 700 °C for 15 h in an O2 atmosphere to obtain a cathode material with a Co-coated layer.

[0297] Example 25

[0298] Example 25 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, the following step S3 is performed:

[0299] S3: Mix the substrate particles obtained in S1 with Al2O3, so that the amount of Al added is 3000ppm (based on the total weight of the substrate particles), and sinter the mixture at 500℃ for 5h in an O2 atmosphere to obtain a cathode material with an Al-coated layer.

[0300] Example 26

[0301] Example 26 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, the following step S3 is performed:

[0302] S3: Mix the substrate particles obtained in S1 with B2O3, so that the amount of B added is 2000ppm (based on the total weight of the substrate particles), and sinter the mixture at 500℃ for 5h in an O2 atmosphere to obtain a cathode material with a B-coated layer.

[0303] Example 27

[0304] Example 27 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, steps S2 and S3 as described below were performed:

[0305] S2: Mix the substrate particles obtained in S1 with H2WO4, so that the amount of W added is 2000ppm (based on the total weight of the substrate particles), and sinter the mixture at 700°C for 15h in an O2 atmosphere.

[0306] S3: The sintered material obtained in S2 is mixed with B2O3 to a B content of 2000 ppm. The mixture is then sintered at 500 °C for 5 h in an O2 atmosphere. A cathode material with a W and B coating is obtained.

[0307] Example 28

[0308] Example 28 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, steps S2 and S3 as described below were performed:

[0309] S2: Mix the substrate particles obtained in S1 with CoO, so that the amount of Co added is 16000ppm (based on the total weight of the substrate particles). Sinter the mixture at 700°C for 15h in an O2 atmosphere.

[0310] S3: The sintered material obtained in S2 is mixed with B2O3, and the amount of B added is 2000ppm (based on the total weight of the substrate particles). The mixture is sintered at 500℃ for 5h in an O2 atmosphere to obtain a cathode material with a coating containing Co and B.

[0311] Example 29

[0312] Example 29 is the same as Example 1 in step S1, except that after obtaining the substrate particles in step S1, steps S2 and S3 as described below were performed:

[0313] S2: The substrate particles obtained in S1 are mixed with CoO and H2WO4, with the amount of Co added being 16000ppm and the amount of W added being 2000ppm, both based on the total weight of the substrate particles. The mixture is sintered at 700℃ for 15h in an O2 atmosphere.

[0314] S3: The sintered material obtained in S2 is mixed with Al2O3 and B2O3, with the amount of Al added being 3000ppm and the amount of B added being 2000ppm, and the Al coating amount: B coating amount being 1.5:1. The mixture is sintered at 500℃ for 5h in an O2 atmosphere to obtain a positive electrode material with a coating layer.

[0315] Examples 30-44

[0316] The difference between this embodiment and embodiment 29 is that the content of the elements in steps S2 and S3 has been adjusted. For details of the content and performance test data, please refer to Tables 3-4 below.

[0317] The presence and thickness of the coating layer can be observed using scanning electron microscopy. Under the microscope, the coating layer appears as a layer independent of the substrate particles. The content of various elements in the coating layer is quantitatively determined using EDS elemental distribution analysis under scanning electron microscopy.

[0318] Table 3

[0319]

[0320] Table 4

[0321]

[0322]

[0323] As can be seen from Tables 3-4, after coating, the capacity and cycle performance of the cathode material of the present invention are further improved, the amount of surface impurities is reduced, and gas expansion is significantly improved, thereby improving the safety performance of the battery.

[0324] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A positive electrode material, comprising substrate particles with a chemical composition of formula (I): Li 1+a [Ni x Co y Mr z M b W c ]O2 (I) in, M includes one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Ca, Zn, and Sr, 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, 0 < a < 0.2, 0 < b < 0.1, 0 < c < 0.1, x + y + z + b + c = 1; and W is enriched at the grain boundaries of the substrate particles; the weight ratio of M element to W element is 1:(0.1 - 1); based on the total weight of the substrate particles, the content of W in the substrate particles is 100 - 3000 ppm; the content of W within a thickness of 40 nm from the grain boundary is at least 80 wt%, based on the total weight of W in the substrate particles.

2. The positive electrode material according to claim 1, wherein the formula (I) satisfies one or more of the following conditions (1) to (7): (1) M includes one or more of Zr, Al, Mg, and Ti; （2）0.8≤x<1； （3）0<a<0.08； （4）0<b<0.018； （5）0<c<0.0013； (6) (1 + a):(x + y + z) = 1.01 - 1.25; (7) The weight ratio of M element to W element is 1:(0.1 - 0.5).

3. The positive electrode material according to claim 1 or 2, wherein b:c = 5 - 69.

4. The positive electrode material according to claim 1 or 2, wherein b:c = 13 - 69.

5. The positive electrode material according to claim 1 or 2, wherein (1 + a):(x + y + z) = 1.05 - 1.

15.

6. The positive electrode material according to claim 1 or 2, wherein in the substrate particles, the content of W within a thickness of 40 nm from the grain boundary is at least 90 wt%, based on the total weight of W in the substrate particles.

7. The positive electrode material according to claim 1 or 2, wherein based on the total weight of the substrate particles, the content of W in the substrate particles is 500 - 2500 ppm.

8. The cathode material according to claim 1 or 2, wherein the volumetric particle size distribution of the cathode material has a diameter (D) v 90-D v 10) / D v 50 is 1.1~1.

8.

9. The cathode material according to claim 1 or 2, wherein the volumetric particle size distribution of the cathode material has a diameter (D) v 90-D v 10) / D v 50 represents 1.2~1.

5.

10. The cathode material according to claim 1 or 2, wherein the volumetric particle size distribution of the cathode material has a diameter (D) v 90-D v 10) / D v 50 is 1.25~1.

45.

11. The positive electrode material according to claim 1 or 2, further comprising a coating layer provided on the surface of the substrate particles, the coating layer containing at least one of W, Co, Al, and B elements.

12. The positive electrode material according to claim 11, wherein the coating layer contains at least W element and / or B element.

13. The positive electrode material according to claim 11, wherein the coating layer includes W, Co, Al, and B elements.

14. The positive electrode material according to claim 11, wherein the coating layer satisfies one or more of the following conditions (1) to (5): (1) The coating layer contains 100 ppm - 2000 ppm of W element, based on the total weight of the substrate particles; (2) The coating layer contains 100 ppm - 16000 ppm of Co element, based on the total weight of the substrate particles; (3) The coating layer contains 100 ppm - 3000 ppm of Al element, based on the total weight of the substrate particles; (4) The coating layer contains 100 ppm - 2000 ppm of B element, based on the total weight of the substrate particles; (5) The coating layer contains elements W, Co, Al, and B, and the total amount of these four elements is 1000 - 22000 ppm, based on the total weight of the substrate particles.

15. The positive electrode material according to claim 11, wherein the coating layer satisfies one or more of the following conditions (1) to (5): (1) The coating layer contains 500 ppm - 1000 ppm of element W, based on the total weight of the substrate particles; (2) The coating layer contains 1000 ppm - 13000 ppm of element Co, based on the total weight of the substrate particles; (3) The coating layer contains 500 ppm - 2000 ppm of element Al, based on the total weight of the substrate particles; (4) The coating layer contains 500 ppm - 1500 ppm of element B, based on the total weight of the substrate particles; (5) The coating layer contains elements W, Co, Al, and B, and the total amount of these four elements is 1000 - 15000 ppm, based on the total weight of the substrate particles.

16. A method for preparing a positive electrode material, the positive electrode material comprising substrate particles having a chemical composition of formula (I): Li 1+a [Ni x Co y Mr z M b W c ]O2 (I) in, M includes one or more of Mo, Zr, Al, Ti, Sb, Nb, Te, Mg, Ca, Zn, and Sr, 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, 0 < a < 0.2, 0 < b < 0.1, 0 < c < 0.1, x + y + z + b + c = 1; and W is enriched at the grain boundaries of the substrate particles; the weight ratio of element M to element W is 1:(0.1 - 1); based on the total weight of the substrate particles, the content of W in the substrate particles is 100 - 3000 ppm; the content of W within a thickness of 40 nm from the grain boundaries is at least 80 wt%, based on the total weight of W in the substrate particles; The method includes the following steps: -S0: Provide a precursor material with a chemical composition of Ni x Co y Mn z (OH)2, where 0.6 ≤ x < 1, 0 < y < 0.4, 0 < z < 0.4, and x + y + z = 1 - S1: Grind and mix the precursor material with a W source compound, then add a Li source compound and an M source compound thereto and mix well, and sinter the mixture to obtain the substrate particles.

17. The method according to claim 16, wherein the particle size of the W source compound particles is 20 - 500 nm; and / or wherein the W source compound includes one or more of WO3, H2WO4, Li2WO4, (NH4)2WO4, MgWO4, and Zr(WO3)2; and / or wherein the addition amount of element W is 100 - 3000 ppm, based on the total weight of the precursor material.

18. The method according to claim 16, wherein the particle size of the W source compound particles is 50 - 300 nm; and / or wherein the W source compound includes one or more of WO3, H2WO4, and Li2WO4; and / or wherein the addition amount of element W is 500 - 2500 ppm, based on the total weight of the precursor material.

19. The method according to any one of claims 16 to 18, wherein the M source compound comprises sulfates, nitrates, chlorides, carbonates, oxides, hydroxides, oxalates, and acetates containing the M element.

20. The method according to any one of claims 16 to 18, wherein the M source compound is an oxide of element M.

21. The method according to any one of claims 16 to 18, wherein the M element in the M source compound is one or more of Zr, Al, Mg and Ti.

22. The method according to any one of claims 16 to 18, wherein the amount of the M element added in the M source compound is 100 to 5000 ppm, based on the total weight of the precursor material.

23. The method according to any one of claims 16 to 18, wherein the amount of the M element added in the M source compound is 500 to 3000 ppm, based on the total weight of the precursor material.

24. The method according to any one of claims 16 to 18, wherein step S1 satisfies at least one of the following conditions: (1) The weight ratio of added M element to W element is 1:(0.1~0.5); (2) Make the ratio between the molar amount of Li atoms and the total molar amount of Ni, Co and Mn atoms 1.01~1.

25.

25. The method according to any one of claims 16 to 18, wherein in step S1 the ratio between the molar amount of Li atoms and the total molar amount of Ni, Co, and Mn atoms is 1.05 to 1.

15.

26. The method according to any one of claims 16 to 18, wherein the grinding and mixing is performed by mechanical grinding or ball milling.

27. The method according to any one of claims 16 to 18, wherein the grinding and mixing are carried out in a ball mill.

28. The method according to any one of claims 16 to 18, wherein the grinding speed is 500 to 3000 r / min.

29. The method according to any one of claims 16 to 18, wherein the grinding speed is 1000 to 2000 r / min.

30. The method according to any one of claims 16 to 18, wherein the grinding speed is 800 to 1500 r / min.

31. The method according to any one of claims 16 to 18, wherein the grinding and mixing are carried out at a temperature of 30 to 100°C.

32. The method according to any one of claims 16 to 18, wherein the grinding and mixing are carried out at a temperature of 40 to 60°C.

33. The method according to any one of claims 16 to 18, further comprising the step of forming a coating layer on the surface of the substrate particles, comprising: -S2: The substrate particles obtained from S1 are mixed with W-containing compounds and / or Co-containing compounds and then sintered; and / or -S3: The substrate particles obtained from S1 or the sinter obtained from S2 are mixed with an Al-containing compound and / or a B-containing compound and then sintered.

34. The method of claim 33, wherein step S2 satisfies one or more of the following conditions: (1) The W-containing compound includes one or more of WO3, H2WO4, Li2WO4, (NH4)2WO4, MgWO4, and Zr(WO3)2; (2) The amount of W added is 100~2000ppm, based on the total weight of the precursor material.

35. The method according to claim 33, wherein step S2 satisfies that the amount of W added is 500~1000 ppm, based on the total weight of the precursor material.

36. The method of claim 33, wherein step S2 satisfies one or more of the following conditions: (1) The Co-containing compound includes one or more of Co3O4, Co(OH)2, CoO, CoOOH, Co(CH3COO)2, CoC2O4, and CoCO3; (2) The amount of Co added is 100~16000ppm, based on the total weight of the precursor material.

37. The method of claim 33, wherein step S2 satisfies that the amount of Co added is 1000~13000 ppm, based on the total weight of the precursor material.

38. The method according to claim 33, wherein in step S3, the Al-containing compound comprises one or more of Al₂O₃, Al(OH)₃, Al₂(SO₄)₃, AlCl₃, and Al(NO₃)₃; and / or The amount of Al added is 100~3000ppm, based on the total weight of the precursor materials.

39. The method according to claim 33, wherein in step S3, the amount of Al added is 500 to 2000 ppm, based on the total weight of the precursor material.

40. The method according to claim 33, wherein in step S3, the B-containing compound comprises one or more of BCl3, B2(SO4)3, B(NO3)3, BN, B2O3, BF3, BBr3, BI3, H2BO5P, H3BO3, C5H6B(OH)2, C3H9B3O6, (C2H5O)3B, and (C3H7O)3B, and / or The amount of B added is 100~2000ppm, based on the total weight of the precursor materials.

41. The method according to claim 33, wherein in step S3, the amount of B added is 500 to 1500 ppm, based on the total weight of the precursor material.

42. The method according to any one of claims 16-18, 34-41, wherein the volumetric particle size distribution radius of the precursor material is 1.1-1.8; and / or The precursor material D v 50 represents 5μm to 15μm.

43. The method according to any one of claims 16-18, 34-41, wherein the volumetric particle size distribution radius of the precursor material is 1.2-1.5; and / or The precursor material D v 50 represents 5μm to 10μm.

44. A secondary battery comprising the positive electrode material according to any one of claims 1 to 15 or the positive electrode material obtained by the method according to any one of claims 16 to 43.

45. An electrical device comprising a secondary battery selected from the options of claim 44.

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