WO2025077884A1 - Lithium-ion secondary battery, positive electrode active material composition, positive electrode sheet and device - Google Patents

Abstract

The present invention belongs to the technical field of batteries, and relates to a lithium-ion secondary battery, a positive electrode active material composition, a positive electrode sheet and a device. The lithium-ion secondary battery comprises a positive electrode active material composition. The positive electrode active material composition comprises three lithium nickel cobalt manganese oxides with different volume average particle sizes Dv50, and a ratio of volume average particle sizes Dv50 of the three lithium nickel cobalt manganese oxides is controlled to be (3-2.2):(2.1-1.5):1. By means of three-stage mixing, the compaction density of the positive electrode active material composition can be increased, and the energy density of the lithium-ion secondary battery is increased.

Description

Lithium ion secondary battery, positive electrode active material composition, positive electrode sheet and equipment

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Chinese patent application 2023113270845, entitled “Positive Electrode Active Material Composition, Positive Electrode Sheet, Battery and Electrical Equipment” filed on October 13, 2023, the entire contents of which are incorporated herein by reference.

Technical Field

The present application relates to the technical field of lithium batteries, and in particular to a positive electrode active material composition, a positive electrode sheet, a battery and an electrical device.

Background Art

In recent years, lithium-ion batteries have made great progress. They can be widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as electric vehicles, power tools, military equipment, aerospace and other fields. Among them, when lithium-ion batteries are used in electric vehicles such as electric bicycles, electric motorcycles and electric vehicles, as the market has higher and higher requirements for the endurance of electric vehicles, how to improve the energy density of batteries needs to be further solved.

Summary of the invention

In view of this, the present application provides a positive electrode active material composition, a positive electrode plate, a battery and an electrical device, which can increase the compaction density of the positive electrode active material composition and increase the energy density of the battery.

The first aspect of the present application provides a lithium-ion secondary battery, including a positive electrode plate, the positive electrode plate includes a positive electrode active material composition, the positive electrode active material composition includes a first lithium nickel cobalt manganese oxide, a second lithium nickel cobalt manganese oxide and a third lithium nickel cobalt manganese oxide, each of which has a volume average particle size Dv50 in the range of 1 μm-8.8 μm, and the volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is (3-2.2):(2.1-1.5):1.

In the technical solution of the embodiment of the present application, the positive electrode active material composition of the lithium-ion secondary battery provides three lithium nickel cobalt manganese oxides with different volume average particle sizes Dv50, which are mixed, and the volume average particle size Dv50 of the lithium nickel cobalt manganese oxides is distributed in the range of 1μm-8.8μm, and by controlling the ratio of the volume average particle sizes Dv50 of the three lithium nickel cobalt manganese, the particle size difference range of the volume average particle sizes Dv50 of the three lithium nickel cobalt manganese can be accurately controlled, so that the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles is improved, the three-level coordination effect of the positive electrode active material composition is better, the compaction density of the positive electrode active material composition is improved, the energy density of the positive electrode active material composition can be improved, and the energy density of the lithium-ion secondary battery is improved.

In any embodiment, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is in the range of 1.5 μm-8.8 μm. In the embodiment of the present application, the positive electrode active material composition within this range has a higher compaction density and higher cycle stability.

In the technical solution of the embodiment of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 3μm-8.8μm; the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 2μm-8μm; the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1μm-4μm. By controlling the range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides, the difference range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides can be further controlled, so that the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles is higher, the three-level coordination effect of the positive electrode active material composition is better, so that the compaction density of the positive electrode active material composition is improved, and the energy density of the positive electrode active material composition can be improved.

In any embodiment, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 4 μm-6 μm. In the technical solution of the embodiment of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is further adjusted so that the first lithium nickel The cobalt manganese oxide has a better mixing effect with the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide, so that the compaction density of the positive electrode active material composition is better, and the energy density and cycle stability of the positive electrode active material composition can be improved.

In any embodiment, the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 3 μm-5 μm. In the technical solution of the embodiment of the present application, by adjusting the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide, the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide, and the third lithium nickel cobalt manganese oxide are mixed better, so that the compaction density of the positive electrode active material composition is better. The energy density and cycle stability of the positive electrode active material composition can be improved.

In any embodiment, the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1.5 μm-3 μm. In the technical solution of the embodiment of the present application, by adjusting the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide, the mixing effect of the third lithium nickel cobalt manganese oxide with the second lithium nickel cobalt manganese oxide and the first lithium nickel cobalt manganese oxide is better, so that the compaction density of the positive electrode active material composition is better. The energy density and cycle stability of the positive electrode active material composition can be improved.

In any embodiment, the mass ratio of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is (2.5-5): 1. In the technical solution of the embodiment of the present application, by controlling the mass of the first lithium nickel cobalt manganese oxide with the largest volume average particle size Dv50 to be greater than the mass of the second lithium nickel cobalt manganese oxide with a larger volume average particle size Dv50, and controlling the ratio of the average particle sizes Dv50 of the two lithium nickel cobalt manganese oxides, the gap formed by the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is greater than the gap formed by only the second lithium nickel cobalt manganese oxide, so that more gaps can be filled in the third lithium nickel cobalt manganese oxide, the effect of the triple mixed grading is improved, and the compaction density of the positive electrode active material is improved. In the technical solution of the embodiment of the present application, the overall volume occupancy ratio of the gaps formed between the lithium nickel cobalt manganese oxide particles can be increased, and the compaction density of the positive electrode active material can be increased.

In any embodiment, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is 60%-97.6%. In the technical solution of the embodiment of the present application, by controlling the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the positive electrode active material to be larger, the gap volume formed by the first nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the positive electrode active material composition is larger, which is conducive to increasing the third lithium nickel cobalt manganese oxide with the smallest average particle size Dv50 to fill in the gap formed by the first nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide, thereby increasing the compaction density of the positive electrode active material.

In any embodiment, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is 70%-80%. By controlling the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the positive electrode active material to be within the range of 70%-80%, the overall volume occupancy ratio of the gaps formed between the lithium nickel cobalt manganese oxide particles is increased, so that the triple mixed gradation of the lithium nickel cobalt manganese oxide in the positive electrode active material is optimized, and the compaction density of the positive electrode active material is optimized.

In any embodiment, the volume distribution particle size Dv10 of the first lithium nickel cobalt manganese oxide is 1 μm-3 μm, the volume distribution particle size Dv90 is 6 μm-11 μm, and the volume distribution particle size Dv99 is 10 μm-17 μm. By controlling the range values of the volume distribution particle sizes Dv10, Dv90 and Dv99 of the first lithium nickel cobalt manganese oxide within the corresponding range, the distribution of the volume distribution particle size Dv10, the volume average particle size Dv50, the volume distribution particle size Dv90 and the volume distribution particle size Dv99 of the first lithium nickel cobalt manganese oxide is determined, so that the compaction density of the positive active material composition is increased and the energy density of the positive active material is increased.

In any embodiment, the volume distribution particle size Dv10 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 10%; the volume average particle size Dv50 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 50%; the volume distribution particle size Dv90 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 90%; the volume distribution particle size Dv99 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 99%. The volume distribution particle size Dv10, the volume average particle size Dv50, the volume distribution particle size Dv90 and the volume distribution particle size Dv99 are common knowledge in the art, have meanings known in the art, and can be measured by methods and instruments in the art.

In any embodiment, the volume distribution particle size Dv10 of the second lithium nickel cobalt manganese oxide is 1 μm-3 μm, the volume distribution particle size Dv90 is 4 μm-10 μm, and the volume distribution particle size Dv99 is 4 μm-12 μm. By controlling the range values of the volume distribution particle sizes Dv10, Dv90 and Dv99 of the second lithium nickel cobalt manganese oxide within the corresponding range, the distribution of the volume distribution particle size Dv10, the volume average particle size Dv50, the volume distribution particle size Dv90 and the volume distribution particle size Dv99 of the second lithium nickel cobalt manganese oxide is determined, so that the compaction density of the positive active material composition is increased and the energy density of the positive active material is increased.

In any embodiment, the volume average particle size Dv10 of the third lithium nickel cobalt manganese oxide is 1 μm-2 μm, the volume distribution particle size Dv90 is 3 μm-6 μm, and the volume distribution particle size Dv99 is 4 μm-8 μm. By controlling the range values of the volume distribution particle sizes Dv10, Dv90 and Dv99 of the third lithium nickel cobalt manganese oxide within the corresponding range, the distribution of the volume distribution particle size Dv10, the volume average particle size Dv50, the volume distribution particle size Dv90 and the volume distribution particle size Dv99 of the third lithium nickel cobalt manganese oxide is determined, so that the compaction density of the positive active material composition is increased and the energy density of the positive active material is increased.

In any embodiment, the first lithium nickel cobalt manganese oxide includes a material with a chemical formula of Li _x1 (Ni _a1 Co _b1 Mn _c1 ) _d1 M _1-d1 O _y1 A z ₁ , the second lithium nickel cobalt manganese oxide includes a material with a chemical formula of Li _x2 (Ni _a2 Co _b2 Mn _c2 ) _d2 M _1-d2 O _y2 A _z2 , and the third lithium nickel cobalt manganese oxide includes a material with a chemical formula of Li _x3 (Ni _a3 Co _b3 Mn _c3 ) _d3 M _1-d3 O _y3 A _z3 , wherein 0.95≤x1≤1.1, 0.3≤a1≤0.7, 0.01≤b1≤0.15, 0.15≤c1≤0.55, a1+b1+c1＝1, 0.95≤d1≤1, 1.9≤y1≤2.1, 0≤z1≤0.1; 0.95≤x2≤1.1, 0.3≤a2≤0.7, 0.01≤b2≤0.15, 0.15≤c2≤0.55, a2+b2+c2＝1, 0.95≤d2≤1, 1.9 ≤y2≤2.1, 0≤z2≤0.1; 0.95≤x3≤1.3, 0.3≤a3≤0.7, 0.06≤b3≤0.20, 0.1≤c3≤0.5, a3+b3+c3＝1, 0.95≤d3≤1, 1.9≤y3≤2.1, 0≤z3≤0.1; M includes one or more of Zr, Sr, B, Ti, Mg, Sn, Mo, W, Sb, Nb, La and Al, and A includes one or more of S, N, F, Cl, Br and I. The first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide all include lithium nickel cobalt manganese oxide, a doping modification material of lithium nickel cobalt manganese oxide, and a surface coating modification material of lithium nickel cobalt manganese oxide. _The surface modification material may be any one or more of MgO, ZrO2, _TiO2 , _Al2O3 , _AlPO4 , _AlF3 , _LiAlO2 , _LiTiO2 and other materials coated on the surface of lithium nickel cobalt manganese oxide, and the technical solution of the present application does not limit the surface modification material. The first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and _the third lithium nickel cobalt manganese oxide may be the same or different, or the first lithium nickel cobalt manganese oxide may be the same as the second lithium nickel cobalt manganese oxide and different from the third lithium nickel cobalt manganese oxide; or the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide may be the same as the first lithium nickel cobalt manganese oxide and different from the first lithium nickel cobalt manganese oxide; the first lithium nickel cobalt manganese oxide may be the same as the third lithium nickel cobalt manganese oxide and different from the second lithium nickel cobalt manganese oxide.

In any embodiment, b1:b2:b3 is 1:(0.5-3):(1-4). By controlling the ratio of the molar content of cobalt element in the nickel-cobalt-manganese transition metal element (hereinafter referred to as cobalt content) in the three nickel-cobalt-manganese oxides, the cobalt content in the third lithium nickel-cobalt-manganese oxide is higher, and the product average particle size Dv50 of the third lithium nickel-cobalt-manganese oxide is smaller. On the one hand, it is beneficial to improve the compaction density of the positive electrode active material composition; on the other hand, the cobalt content in the third lithium nickel-cobalt-manganese oxide is higher, so that the impedance of the third lithium nickel-cobalt-manganese oxide as a negative electrode active material is small, thereby reducing the impedance of the negative electrode active material composition assembled into a battery during the cycle process, reducing the heat generated during the cycle process, improving the power performance of the negative electrode active material, and improving the rate performance of the negative electrode active material.

In any embodiment, b1:b2:b3 is 1:(0.5-1.5):(1-2.5).

In any embodiment, the crystal of one or more of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is a single crystal. The stability of the positive electrode active material can be improved, so that the stability of the positive electrode active material composition is higher, and the cycle stability of the positive electrode active material is increased.

In any embodiment, the compaction density of the positive electrode active material composition is 3 g/cm ³ -4 g/cm ³ . The compaction density of the positive electrode active material composition is relatively large, which is beneficial to improving the energy density of the positive electrode active material composition.

In any embodiment, the positive electrode active material composition has a compaction density of 3.4 g/cm ³ to 3.8 g/cm ³ at a pressure of 2.94×10 ⁴ N.

In any embodiment, the specific surface area of the positive electrode active material composition is ^0.6m2 /g- ^1.0m2 /g. In the embodiment of the present application, the specific surface area of the positive electrode active material composition is small, so that when the positive electrode active material composition is used in a battery, the side reactions during the battery cycle are small, which is beneficial to improve the cycle stability of the battery.

In any embodiment, the positive electrode active material composition has a specific surface area of 0.8 ^{m 2} /g to 0.9 ^{m 2} /g.

According to a second aspect of the present application, a positive electrode active material composition is provided, comprising a first lithium nickel cobalt manganese oxide, a second lithium nickel cobalt manganese oxide and a third lithium nickel cobalt manganese oxide with a volume average particle size Dv50 in the range of 1 μm-8.8 μm, and the volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is (3-2.2):(2.1-1.5):1.

In the technical solution of the embodiment of the present application, the positive electrode active material composition provides three lithium nickel cobalt manganese oxides with different volume average particle sizes Dv50, which are mixed, and the volume average particle size Dv50 of the lithium nickel cobalt manganese oxide is distributed in the range of 1 μm-8.8 μm, and by controlling the ratio of the volume average particle sizes Dv50 of the three lithium nickel cobalt manganese, the volume of the three lithium nickel cobalt manganese can be accurately controlled. The particle size difference range of the average particle size Dv50 increases the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles, and the three-level coordination effect of the positive electrode active material composition is better, which increases the compaction density of the positive electrode active material composition and can increase the energy density of the positive electrode active material composition.

In any embodiment, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is in the range of 1.5 μm-8.8 μm. In the embodiment of the present application, the positive electrode active material composition within this range has a higher compaction density and higher cycle stability.

In the technical solution of the embodiment of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 3μm-8.8μm; the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 2μm-8μm; the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1μm-4μm. By controlling the range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides, the difference range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides can be further controlled, so that the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles is higher, the three-level coordination effect of the positive electrode active material composition is better, so that the compaction density of the positive electrode active material composition is improved, and the energy density of the positive electrode active material composition can be improved.

In any embodiment, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 4 μm-6 μm. In the technical solution of the embodiment of the present application, by further adjusting the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide have a better mixing effect, so that the compaction density of the positive electrode active material composition is better. At the same time, the energy density and cycle stability of the positive electrode active material composition can be improved.

In any embodiment, the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 3 μm-5 μm. In the technical solution of the embodiment of the present application, by adjusting the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide, the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide, and the third lithium nickel cobalt manganese oxide are mixed better, so that the compaction density of the positive electrode active material composition is better. The energy density and cycle stability of the positive electrode active material composition can be improved.

In any embodiment, the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1.5 μm-3 μm. In the technical solution of the embodiment of the present application, by adjusting the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide, the mixing effect of the third lithium nickel cobalt manganese oxide with the second lithium nickel cobalt manganese oxide and the first lithium nickel cobalt manganese oxide is better, so that the compaction density of the positive electrode active material composition is better. The energy density and cycle stability of the positive electrode active material composition can be improved.

In any embodiment, the mass ratio of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is (2.5-5): 1. In the technical solution of the embodiment of the present application, by controlling the mass of the first lithium nickel cobalt manganese oxide with the largest volume average particle size Dv50 to be greater than the mass of the second lithium nickel cobalt manganese oxide with a larger volume average particle size Dv50, and controlling the ratio of the average particle sizes Dv50 of the two lithium nickel cobalt manganese oxides, the gap formed by the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is greater than the gap formed by only the second lithium nickel cobalt manganese oxide, so that more gaps can be filled in the third lithium nickel cobalt manganese oxide, the effect of the triple mixed grading is improved, and the compaction density of the positive electrode active material is improved. In the technical solution of the embodiment of the present application, the overall volume occupancy ratio of the gaps formed between the lithium nickel cobalt manganese oxide particles can be increased, and the compaction density of the positive electrode active material can be increased.

In any embodiment, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is 60%-97.6%. In the technical solution of the embodiment of the present application, by controlling the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the positive electrode active material to be larger, the gap volume formed by the first nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the positive electrode active material composition is larger, which is conducive to increasing the third lithium nickel cobalt manganese oxide with the smallest average particle size Dv50 to fill in the gap formed by the first nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide, thereby increasing the compaction density of the positive electrode active material.

The third aspect of the present application provides a positive electrode sheet, comprising the positive electrode active material composition of the second aspect of the present application. Since the positive electrode sheet of the present application comprises the positive electrode active material composition provided in the second aspect of the present application, it has at least the same advantages as the positive electrode active material composition.

The fourth aspect of the present application provides an electric device, comprising the lithium ion secondary battery of the first aspect of the present application, or/and the positive electrode active material composition of the second aspect, or/and the positive electrode sheet of the third aspect. Thus, it has at least the same advantages as the lithium ion secondary battery provided in the first aspect, or/and the positive electrode active material composition of the second aspect, or/and the positive electrode sheet of the third aspect.

The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a battery cell according to an embodiment of the present application;

FIG2 is a schematic diagram of an exploded structure of a battery according to an embodiment of the present application;

FIG3 is a schematic diagram of a partial structure of an electrical device according to an embodiment of the present application;

FIG4 is a scanning electron microscope image of a first lithium nickel cobalt manganese oxide according to an embodiment of the present application;

FIG. 5 is a scanning electron microscope image of a second lithium nickel cobalt manganese oxide according to an embodiment of the present application.

DETAILED DESCRIPTION

Below, the battery cells, batteries and electrical equipment of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

"Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values or not including end values, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, "include" and "comprising" may represent that other components not listed may also be included or only listed components may be included or only listed components may be included.

If not specifically stated, in this application, the term "or" is inclusive. 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 exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

The particle size of lithium nickel cobalt manganese oxide single crystal is in the micron level between 1-10μm, generally between 2μm-6μm. The particle size distribution range of lithium nickel cobalt manganese oxide in the form of morphology is small, and it is difficult to increase its compaction density by mixing particles of two different particle sizes, resulting in a low energy density of lithium nickel cobalt manganese oxide as a negative electrode active material. Therefore, it is difficult to increase the compaction density of lithium nickel cobalt manganese oxide particles with a particle size of micrometer level and a small particle size distribution range.

Based on this, the first aspect of the present application provides a lithium ion secondary battery, including a positive electrode plate, the positive electrode plate includes a positive electrode active material composition, the positive electrode active material composition includes a first lithium nickel cobalt manganese oxide, a second lithium nickel cobalt manganese oxide and a third lithium nickel cobalt manganese oxide, and the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is in the range of 1μm-8.8μm. The volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is (3-2.2):(2.1-1.5):1.

In the technical scheme of the embodiment of the present application, in the technical scheme of the embodiment of the present application, the three-dimensional positive electrode active material composition of the lithium-ion secondary battery provides three lithium nickel cobalt manganese oxides with three different volume average particle sizes Dv50, which are mixed, and the volume average particle size Dv50 of the lithium nickel cobalt manganese oxide is distributed in the range of 1μm-8.8μm, and by controlling the ratio of the volume average particle sizes Dv50 of the three lithium nickel cobalt manganese, the particle size difference range of the volume average particle sizes Dv50 of the three lithium nickel cobalt manganese can be accurately controlled, so that the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles is improved, the three-level coordination effect of the positive electrode active material composition is better, so that the compaction density of the positive electrode active material composition is improved, and the energy density of the lithium-ion secondary battery can be improved. Among them, the volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide can be 3:2.1:1, 2.8:2.1:1, 2.8:1.9:1, 2.6:1.8:1, 2.4:1.6:1, 2.2:1.5:1, etc., or a range consisting of any two of the above values, for example, (3-2.8):(2.1-1.5):1, (3-2.6):(1.9-1.5):1, (2.8-2.2):(1.8-1.5):1, etc. Among them, the product average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide can be in the range of 1μm-8μm, 1.5μm-8.8μm, 2μm-8.8μm, 2μm-8μm, 2μm-7μm, 2μm-6μm, etc.

In any embodiment, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is in the range of 1.5 μm-8.8 μm. In the embodiment of the present application, the positive electrode active material composition within this range has a higher compaction density and higher cycle stability.

In some embodiments of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 3μm-8.8μm; the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 2μm-8μm; the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1μm-4μm. In the embodiment of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is greater than the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide, and the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is greater than the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide. By controlling the range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides, the difference range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides can be further controlled, so that the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles is higher, the three-level coordination effect of the positive electrode active material composition is better, so that the compaction density of the positive electrode active material composition is improved, and the energy density of the positive electrode active material composition can be improved.

In some embodiments of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide can be 3μm, 3.2μm, 3.6μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.6μm, 5.8μm, 6μm, 6.2μm, 6.6μm, 6.9μm, 7μm, 7.2μm, 7.6μm, 7.8μm, 8μm, 8.2μm, 8.6μm, 8.8μm, etc., or a range consisting of any two of the above values, for example, 3μm-5μm, 5μm-8μm, 8μm-8.8μm, etc. The volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide can be 2μm, 2.2μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.6μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.6μm, 5.8μm, 6μm, 6.2μm, 6.6μm, 6.9μm, 7μm, 7.2μm, 7.6μm, 7.8μm, 8μm, etc., or a range composed of any two of the above values, for example, 2μm-3μm, 3μm-4μm, 4μm-8μm, etc. The volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide can be 1μm, 1.2μm, 1.6μm, 1.8μm, 2μm, 2.2μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.6μm, 3.8μm, 4μm, etc., or a range consisting of any two of the above values, for example, 1μm-2μm, 2μm-3μm, 3μm-4μm, etc. The above-mentioned volume average particle size Dv50 must satisfy: the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is greater than the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide, the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is greater than the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide, and the volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is (3-2.2):(2.1-1.5):1.

In the technical solution of the embodiment of the present application, the difference in volume average particle size Dv50 between the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide may be between 0.8 μm and 4.1 μm, for example, it may be 0.8 μm, 1 μm, 1.5 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.1 μm, etc.; the difference in volume average particle size Dv50 between the second lithium nickel cobalt manganese oxide and the first lithium nickel cobalt manganese oxide may be 4 μm-1.6 μm, for example, it may be 1.6 μm, 1 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.3 μm, 3.5 μm, 4 μm, etc.; but it is still under the premise that the ratio of volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is (3-2.2):(2.1-1.5):1.

In the technical solution of the embodiment of the present application, the positive electrode active material composition adopts three lithium nickel cobalt manganese oxides with different volume average particle sizes Dv50, which are mixed, and the volume average particle size Dv50 of the lithium nickel cobalt manganese oxide is distributed in the range of 1μm-8.8μm, and the distribution range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides is controlled, so that the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles is increased, so that the compaction density of the positive electrode active material composition is increased, and the energy density of the positive electrode active material composition can be improved.

In some embodiments of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 4μm-6μm. In the technical solution of the embodiment of the present application, by further regulating the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the mixing effect of the first lithium nickel cobalt manganese oxide with the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is better, so that the compaction density of the positive electrode active material composition is better. At the same time, the energy density and cycle stability of the positive electrode active material composition can be improved. Among them, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide can be 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.6μm, 5.8μm, 6μm, etc., or a range composed of any two of the above values, for example, 4μm-4.8μm, 4.8μm-5.2μm, 5.2μm-6μm, etc.

In some embodiments of the present application, the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 3μm-5μm. In the technical solution of the embodiment of the present application, by adjusting the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide, the mixing effect of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide, and the third lithium nickel cobalt manganese oxide is better, so that the compaction density of the positive electrode active material composition is better. The energy density and cycle stability of the positive electrode active material composition can be improved. Among them, the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide can be 3μm, 3.2μm, 3.6μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, etc., or a range composed of any two of the above values, for example, 3μm-3.6μm, 3.6μm-4.2μm, 4.2μm-5μm, etc.

In some embodiments of the present application, the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1.5μm-3μm. In the technical solution of the embodiment of the present application, by adjusting the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide, the mixing effect of the third lithium nickel cobalt manganese oxide with the second lithium nickel cobalt manganese oxide and the first lithium nickel cobalt manganese oxide is better, so that the compaction density of the positive electrode active material composition is better. The energy density and cycle stability of the positive electrode active material composition can be improved. Among them, the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide can be 1.5μm, 1.8μm, 2μm, 2.2μm, 2.6μm, 2.8μm, 3μm, etc., or a range composed of any two of the above values, for example, 1.5μm-2μm, 2μm-2.6μm, 2.6μm-3μm, etc.

In some embodiments of the present application, the mass ratio of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is (2.5-5): 1. In the technical solution of the embodiment of the present application, by controlling the mass of the first lithium nickel cobalt manganese oxide with the largest volume average particle size Dv50 to be greater than the mass of the second lithium nickel cobalt manganese oxide with a larger volume average particle size Dv50, and controlling the ratio of the average particle sizes Dv50 of the two lithium nickel cobalt manganese oxides, the gap formed by the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is greater than the gap formed by only the second lithium nickel cobalt manganese oxide, so that the gap that can be filled with the third lithium nickel cobalt manganese oxide is increased, the effect of the triple mixed grading is improved, and the compaction density of the positive electrode active material is improved. In the technical solution of the embodiment of the present application, the overall volume occupancy ratio of the gap formed between the lithium nickel cobalt manganese oxide particles can be increased, and the compaction density of the positive electrode active material can be increased. Among them, the mass ratio of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide can be 2.5:1, 4:1, 4.2:1, 4.4:1, 4.5:1, 4.6:1, 4.8:1, 4.9:1, 5:1, etc., or a range consisting of any two of the above values, for example, (2.5-4):1, (4-4.4):1, (4.4-5):1, etc.

In some embodiments of the present application, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is 60%-97.6%. In the technical solution of the embodiment of the present application, by controlling the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second nickel cobalt manganese oxide in the positive electrode active material to be larger, the positive electrode active material The gap volume formed by the first nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the material composition is large, which is conducive to increasing the third lithium nickel cobalt manganese oxide with the smallest average particle size Dv50 to fill into the gap formed by the first nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide, thereby increasing the compaction density of the positive electrode active material. Wherein, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide can be 60%, 65%, 70%, 75%, 77%, 80%, 85%, 86%, 90%, 97.6%, etc., or a range composed of any two of the above values, for example, 60%-70%, 70%-85%, 85%-90%, 90%-97.6%, etc.

In some embodiments of the present application, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is 70%-80%. By controlling the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the positive electrode active material within the range of 70%-80%, the overall volume occupancy ratio of the gaps formed between the lithium nickel cobalt manganese oxide particles is increased, so that the triple mixed gradation of the lithium nickel cobalt manganese oxide in the positive electrode active material is optimized, and the compaction density of the positive electrode active material is optimized. Among them, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide can be 70%, 72%, 75%, 77%, 78%, 80%, etc., or a range composed of any two of the above values, for example, 70%-75%, 75%-78%, 78%-80%, etc.

In some embodiments of the present application, the volume distribution particle size Dv10 of the first lithium nickel cobalt manganese oxide is 1 μm-3 μm, the volume distribution particle size Dv90 is 6 μm-11 μm, and the volume distribution particle size Dv99 is 10 μm-17 μm. By controlling the range values of the volume distribution particle sizes Dv10, Dv90 and Dv99 of the first lithium nickel cobalt manganese oxide within the corresponding range, the distribution of the volume distribution particle sizes Dv10, Dv50, Dv90 and Dv99 of the first lithium nickel cobalt manganese oxide is determined, so that the compaction density of the positive electrode active material composition is increased, and the energy density of the positive electrode active material is increased. Among them, the volume distribution particle size Dv10 of the first lithium nickel cobalt manganese oxide can be 1μm, 2μm, 3μm, etc., the volume distribution particle size Dv90 can be 6μm, 7μm, 8μm, 9μm, 10μm, etc., and the volume distribution particle size Dv99 can be 10μm, 12μm, 13μm, 15μm, 17μm, etc.

In any embodiment, the volume distribution particle size Dv10 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 10%; the volume average particle size Dv50 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 50%; the volume distribution particle size Dv90 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 90%; the volume distribution particle size Dv99 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 99%. The volume distribution particle size Dv10, the volume average particle size Dv50, the volume distribution particle size Dv90 and the volume distribution particle size Dv99 are common knowledge in the art, have meanings known in the art, and can be measured by methods and instruments in the art.

In some embodiments of the present application, the volume distribution particle size Dv10 of the second lithium nickel cobalt manganese oxide is 1 μm-3 μm, the volume distribution particle size Dv90 is 4 μm-10 μm, and the volume distribution particle size Dv99 is 4 μm-12 μm. By controlling the range values of the volume distribution particle sizes Dv10, Dv90 and Dv99 of the second lithium nickel cobalt manganese oxide within the corresponding range, the distribution of the volume distribution particle size Dv10, the volume average particle size Dv50, the volume distribution particle size Dv90 and the volume distribution particle size Dv99 of the second lithium nickel cobalt manganese oxide is determined, so that the compaction density of the positive electrode active material composition is increased, and the energy density of the positive electrode active material is increased. Among them, the volume distribution particle size Dv10 of the second lithium nickel cobalt manganese oxide can be 1μm, 2μm, 3μm, etc., the volume distribution particle size Dv90 can be 4μm, 5μm, 7μm, 8μm, 9μm, 10μm, etc., and the volume distribution particle size Dv99 can be 4μm, 8μm, 10μm, 11μm, 12μm, etc.

In some embodiments of the present application, the volume average particle size Dv10 of the third lithium nickel cobalt manganese oxide is 1 μm-2 μm, the volume distribution particle size Dv90 is 3 μm-6 μm, and the volume distribution particle size Dv99 is 4 μm-8 μm. By controlling the range values of the volume distribution particle sizes Dv10, Dv90 and Dv99 of the third lithium nickel cobalt manganese oxide within the corresponding range, the distribution of the volume distribution particle size Dv10, the volume average particle size Dv50, the volume distribution particle size Dv90 and the volume distribution particle size Dv99 of the third lithium nickel cobalt manganese oxide is determined, so that the compaction density of the positive active material composition is increased, and the energy density of the positive active material is increased. Among them, the volume distribution particle size Dv10 of the third lithium nickel cobalt manganese oxide can be 1μm, 1.5μm, 2μm, etc., the volume distribution particle size Dv90 can be 3μm, 4μm, 5μm, 6μm, etc., and the volume distribution particle size Dv99 can be 4μm, 5μm, 6μm, 7μm, 8μm, etc.

In some embodiments of the present application, the first lithium nickel cobalt manganese oxide includes a material with a chemical formula of Li _x1 (Ni _a1 Co _b1 Mn _c1 ) _d1 M _1-d1 O _y1 Az ₁ , the second lithium nickel cobalt manganese oxide includes a material with a chemical formula of Li _x2 (Ni _a2 Co _b2 Mn _c2 ) _d2 M _1-d2 O _y2 A _z2 , and the third lithium nickel cobalt manganese oxide includes a material with a chemical formula of Li _x3 (Ni _a3 Co _b3 Mn _c3 ) _d3 M _1-d3 O _y3 A _z3 material, among which, 0.95≤x1≤1.1, 0.3≤a1≤0.7, 0.01≤b1≤0.15, 0.15≤c1≤0.55, a1+b1+c1=1, 0.95≤d1≤1, 1.9≤y1≤ 2.1, 0≤z1≤0.1; 0.95≤x2≤1.1, 0.3≤a2≤0.7, 0.01≤b2≤0.15, 0.15≤c2≤0.55, a2+b2+c2=1, 0.95≤d2≤1, 1.9 ≤y2≤2.1, 0≤z2≤0.1; 0.95≤x3≤1.3, 0.3≤a3≤0.7, 0.06≤b3≤0.20, 0.1≤c3≤0.5, a3+b3+c3＝1, 0.95≤d3≤1, 1.9≤y3≤2.1, 0≤z3≤0.1; M includes one or more of Zr, Sr, B, Ti, Mg, Sn, Mo, W, Sb, Nb, La and Al, and A includes one or more of S, N, F, Cl, Br and I. The first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide all include lithium nickel cobalt manganese oxide, a doping modification material of lithium nickel cobalt manganese oxide, and a surface coating modification material of lithium nickel cobalt manganese oxide. _The surface modification material may be any one or more of MgO, ZrO2, _TiO2 , _Al2O3 , _AlPO4 , _AlF3 , _LiAlO2 , _LiTiO2 and other materials coated on the surface of lithium nickel cobalt manganese oxide, and the technical solution of the present application does not limit the surface modification material. The first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and _the third lithium nickel cobalt manganese oxide may be the same or different, or the first lithium nickel cobalt manganese oxide may be the same as the second lithium nickel cobalt manganese oxide and different from the third lithium nickel cobalt manganese oxide; or the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide may be the same as the first lithium nickel cobalt manganese oxide and different from the first lithium nickel cobalt manganese oxide; the first lithium nickel cobalt manganese oxide may be the same as the third lithium nickel cobalt manganese oxide and different from the second lithium nickel cobalt manganese oxide. Among them, x1 and x2 can be 0.95, 1, 1.05, 1.1, etc., respectively, a1, a2, a3 can be 0.3, 0.4, 0.5, 0.7, etc., b1 can be 0.01, 0.05, 0.1, 0.15, etc., c1 and c2 can be 0.01, 0.2, 0.3, etc., respectively, d1, d2, d3 can be 0.95, 0.98, 1, etc., respectively, y1, y2, y3 can be 1.9, etc., respectively. , 1.95, 2, 2.05, 2.1, etc., z1, z2, z3 can be 0, 0.05, 0.1, etc. respectively; c3 can be 0.01, 0.1, 0.13, 0.15, 0.2, 0.3, 0.4, 0.5, etc., x3 can be 0.95, 1.0, 1.1, 1.2, 1.3, etc., b3 can be 0.06, 0.1, 0.15, 0.20, etc., b2 can be 0.01, 0.1, 0.2, 0.3, 0.5, etc.

In any embodiment, b1:b2:b3 is 1:(0.5-3):(1-4). By controlling the ratio of the molar content of cobalt element in nickel-cobalt-manganese transition metal elements (referred to as cobalt content) in the three nickel-cobalt-manganese oxides, the cobalt content in the third lithium nickel-cobalt-manganese oxide is higher, and the product average particle size Dv50 of the third lithium nickel-cobalt-manganese oxide is smaller. On the one hand, it is beneficial to improve the compaction density of the positive electrode active material composition; on the other hand, the cobalt content in the third lithium nickel-cobalt-manganese oxide is higher, so that the impedance of the third lithium nickel-cobalt-manganese oxide as a negative electrode active material is small, thereby reducing the impedance of the negative electrode active material composition assembled into a battery during the cycle process, reducing the heat generated during the cycle process, improving the power performance of the negative electrode active material, and improving the rate performance of the negative electrode active material. The third lithium nickel-cobalt-manganese oxide may also have the same cobalt content as the first lithium nickel-cobalt-manganese oxide. Among them, b1:b2:b3 can be 1:0.5:2.5, 1:0.5:1, 1:0.5:1.5, 1:0.5:1.8, 1:0.5:2, 1:1:2.5, 1:1.5:2, 1:1.5:2, 1:1.5:2.5, 1:1:1, 1:0.5:3, 1:0.5:4, 1:1.5:4, 1:1:3, 1:1:4, etc.

In any embodiment, b1:b2:b3 is 1:(0.5-1.5):(1-2.5). Among them, b1:b2:b3 can be 1:0.5:2.5, 1:0.5:1, 1:0.5:1.5, 1:0.5:1.8, 1:0.5:2, 1:1:2.5, 1:1.5:2, 1:1.5:2, etc.

In some embodiments of the present application, the crystals of one or more of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide, and the third lithium nickel cobalt manganese oxide are single crystals. The stability of the positive electrode active material can be improved, so that the stability of the positive electrode active material composition is higher, and the cycle stability of the positive electrode active material is increased.

In some embodiments of the present application, under a pressure of 2.94×10 ⁴ N, the compaction density of the positive electrode active material composition is 3g/cm ³ -4g/cm ³ . The compaction density of the positive electrode active material composition is relatively large, which is beneficial to improving the energy density of the positive electrode active material composition. Wherein, the compaction density of the positive electrode active material composition is 3g/cm ³ , 3.2g/cm ³ , 3.6g/cm ³ , 3.8g/cm ³ , 4g/cm ³ , etc., or a range consisting of any two of the above values, for example, 3g/cm ³ -3.2g/cm ³ , 3.2g/cm ³ -3.6g/cm ³ , 3.6g/cm ³ -4g/cm ³ , etc.

In some embodiments of the present application, the compaction density of the positive electrode active material composition is 3 g/cm ³ -3.5 g/cm ³ under a pressure of 2.94×10 ⁴ N. The compaction density of the positive electrode active material composition is 3 g/cm ³ , 3.1 g/cm ³ , 3.2 g/cm ³ , 3.3 g/cm ³ , 3.5 g/cm ³ , etc., or a range consisting of any two of the above values, for example, 3 g/cm ³ -3.2 g/cm ³ , 3.2 g/cm ³ -3.4 g/cm ³ , 3.4 g/cm ³ -3.5 g/cm ³ , etc.

In some embodiments of the present application, the specific surface area of the positive electrode active material composition is 0.6 m ² /g-1.0 ^{m 2} /g. The specific surface area of the positive electrode active material composition of the present application is small, so that when the positive electrode active material composition is used in a battery, the battery cycle process The side reactions are small, which is beneficial to improve the cycle stability of the battery. The specific surface area of the positive electrode active material composition is 0.6m2 ^/ g, ^0.8m2 /g, ^0.9m2 /g, ^1.0m2 /g, etc., or a range consisting of any two of the above values, for example, 0.6m2 ^/ g-0.8m2 ^/ g, 0.8m2 ^/ g-0.9m2 ^/ g, ^0.9m2/g - ^1.0m2 /g, etc.

In some embodiments of the present application, the specific surface area of the cathode active material composition is 0.8 ^{m 2} /g-0.9 ^{m 2} /g, wherein the specific surface area of the cathode active material composition is 0.8 ^{m 2} /g, 0.85 m 2 /g, 0.88 m ² /g, ^0.9 m ² /g, etc.

The second aspect of the present application provides a positive electrode active material composition including a first lithium nickel cobalt manganese oxide, a second lithium nickel cobalt manganese oxide and a third lithium nickel cobalt manganese oxide, wherein the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is in the range of 1 μm-8.8 μm. The volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is (3-2.2):(2.1-1.5):1.

In the technical scheme of the embodiment of the present application, in the technical scheme of the embodiment of the present application, the three-dimensional positive electrode active material composition of the lithium-ion secondary battery provides three lithium nickel cobalt manganese oxides with three different volume average particle sizes Dv50, which are mixed, and the volume average particle size Dv50 of the lithium nickel cobalt manganese oxide is distributed in the range of 1μm-8.8μm, and by controlling the ratio of the volume average particle sizes Dv50 of the three lithium nickel cobalt manganese, the particle size difference range of the volume average particle sizes Dv50 of the three lithium nickel cobalt manganese can be accurately controlled, so that the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles is improved, the three-level coordination effect of the positive electrode active material composition is better, so that the compaction density of the positive electrode active material composition is improved, and the energy density of the lithium-ion secondary battery can be improved. Among them, the volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide can be 3:2.1:1, 2.8:2.1:1, 2.8:1.9:1, 2.6:1.8:1, 2.4:1.6:1, 2.2:1.5:1, etc., or a range consisting of any two of the above values, for example, (3-2.8):(2.1-1.5):1, (3-2.6):(1.9-1.5):1, (2.8-2.2):(1.8-1.5):1, etc. Among them, the product average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide can be in the range of 1μm-8μm, 1.5μm-8.8μm, 2μm-8.8μm, 2μm-8μm, 2μm-7μm, 2μm-6μm, etc.

In any embodiment, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is in the range of 1.5 μm-8.8 μm. In the embodiment of the present application, the positive electrode active material composition within this range has a higher compaction density and higher cycle stability.

In some embodiments of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 3μm-8.8μm; the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 2μm-8μm; the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1μm-4μm. In the embodiment of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is greater than the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide, and the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is greater than the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide. By controlling the range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides, the difference range of the volume average particle size Dv50 of the three lithium nickel cobalt manganese oxides can be further controlled, so that the gap occupancy ratio formed between the lithium nickel cobalt manganese oxide particles is higher, the three-level coordination effect of the positive electrode active material composition is better, so that the compaction density of the positive electrode active material composition is improved, and the energy density of the positive electrode active material composition can be improved.

In some embodiments of the present application, the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide can be 3μm, 3.2μm, 3.6μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.6μm, 5.8μm, 6μm, 6.2μm, 6.6μm, 6.9μm, 7μm, 7.2μm, 7.6μm, 7.8μm, 8μm, 8.2μm, 8.6μm, 8.8μm, etc., or a range consisting of any two of the above values, for example, 3μm-5μm, 5μm-8μm, 8μm-8.8μm, etc. The volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide can be 2μm, 2.2μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.6μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.6μm, 5.8μm, 6μm, 6.2μm, 6.6μm, 6.9μm, 7μm, 7.2μm, 7.6μm, 7.8μm, 8μm, etc., or a range composed of any two of the above values, for example, 2μm-3μm, 3μm-4μm, 4μm-8μm, etc. The volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide may be 1 μm, 1.2 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.6 μm, 3.8 μm, 4 μm, etc., or a range consisting of any two of the above values, for example, 1 μm-2 μm, 2 μm-3 μm, 3 μm-4 μm, etc. The above volume average particle size Dv50 must satisfy: the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is greater than the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide, the volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is greater than the volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide, and the volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is . (3-2.2):(2.1-1.5):1.

In some embodiments of the present application, the mass ratio of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is (2.5-5): 1. In the technical solution of the embodiment of the present application, by controlling the mass of the first lithium nickel cobalt manganese oxide with the largest volume average particle size Dv50 to be greater than the mass of the second lithium nickel cobalt manganese oxide with a larger volume average particle size Dv50, and controlling the ratio of the average particle sizes Dv50 of the two lithium nickel cobalt manganese oxides, the gap formed by the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is greater than the gap formed by only the second lithium nickel cobalt manganese oxide, so that the gap that can be filled with the third lithium nickel cobalt manganese oxide is increased, the effect of the triple mixed grading is improved, and the compaction density of the positive electrode active material is improved. In the technical solution of the embodiment of the present application, the overall volume occupancy ratio of the gap formed between the lithium nickel cobalt manganese oxide particles can be increased, and the compaction density of the positive electrode active material can be increased. Among them, the mass ratio of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide can be 2.5:1, 4:1, 4.2:1, 4.4:1, 4.5:1, 4.6:1, 4.8:1, 4.9:1, 5:1, etc., or a range consisting of any two of the above values, for example, (2.5-4):1, (4-4.4):1, (4.4-5):1, etc.

In some embodiments of the present application, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is 60%-97.6%. In the technical solution of the embodiment of the present application, by controlling the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the positive electrode active material to be larger, the gap volume formed by the first nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide in the positive electrode active material composition is larger, which is conducive to increasing the third lithium nickel cobalt manganese oxide with the smallest average particle size Dv50 to fill in the gap formed by the first nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide, thereby increasing the compaction density of the positive electrode active material. Among them, based on the total mass of the positive electrode active material composition, the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide can be 60%, 65%, 70%, 75%, 77%, 80%, 85%, 86%, 90%, 97.6%, etc., or a range consisting of any two of the above values, for example, 60%-70%, 70%-85%, 85%-90%, 90%-97.6%, etc.

The third aspect of the present application provides a positive electrode sheet, comprising the positive electrode active material composition of the second aspect of the present application. Since the positive electrode sheet of the present application comprises the positive electrode active material composition provided in the second aspect of the present application, it has at least the same advantages as the positive electrode active material composition.

The fourth aspect of the present application provides an electric device, comprising the lithium ion secondary battery of the first aspect of the present application, or/and the positive electrode active material composition of the second aspect, or/and the positive electrode sheet of the third aspect. Thus, it has at least the same advantages as the lithium ion secondary battery provided in the first aspect, or/and the positive electrode active material composition of the second aspect, or/and the positive electrode sheet of the third aspect.

In addition, the battery cell, battery, and electric equipment of the present application will be described below with reference to the drawings as appropriate.

In the embodiments of the present application, a battery cell refers to the smallest unit that makes up a battery. The battery cell also includes an electrolyte and a separator. The separator is arranged between the positive electrode sheet and the negative electrode sheet, and mainly plays the role of preventing the positive and negative electrodes from short-circuiting, while allowing ions to pass through. During the battery charging and discharging process, the active ion Li ⁺ is embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet, and the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.

The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the positive electrode active material composition of the above embodiment of the present application.

As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

In some embodiments, the positive electrode 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 material base and a metal layer formed on at least one surface of the polymer material base. 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 material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the positive electrode film layer may also optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

In some embodiments, the positive electrode film layer may further include a conductive agent, for example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes the negative electrode active material of the above embodiment.

As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

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

In some embodiments, the negative electrode film layer may further 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).

In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the negative electrode film layer may further include other additives, such as a thickener (such as sodium carboxymethyl cellulose (CMC-Na)).

In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

The electrolyte plays a role in conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.

In some embodiments, the electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into a battery cell assembly by a winding process or a lamination process.

In some embodiments, as shown in FIG1 , the battery cell 10 may include an outer package. The outer package may be used to encapsulate the battery cell assembly 11 and the electrolyte. The outer package includes an end cap 12 , a housing 13 and other functional components.

The end cap 12 refers to a component that covers the opening of the shell 13 to isolate the internal environment of the battery cell 10 from the external environment. Without limitation, the shape of the end cap 12 can be adapted to the shape of the shell 13 to match the shell 13. Optionally, the end cap 12 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 12 is not easily deformed when squeezed and collided, so that the battery cell 10 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 12a can be provided on the end cap 12. The electrode terminal 12a can be used to electrically connect to the battery cell assembly 11 for outputting or inputting electrical energy of the battery cell 10. In some embodiments, the end cap 12 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 10 reaches a threshold. The material of the end cap 12 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose special restrictions on this. In some embodiments, an insulating member (not shown) may be provided inside the end cap 12 to isolate the electrical connection components in the housing 13 from the end cap 12 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, or the like.

The shell 13 is a component used to cooperate with the end cap 12 to form the internal environment of the battery cell 10, wherein the formed internal environment can be used to accommodate the battery cell assembly 11, electrolyte and other components. The shell 13 and the end cap 12 can be independent components, and an opening can be set on the shell 13, and the internal environment of the battery cell 10 is formed by covering the opening with the end cap 12 at the opening. Without limitation, the end cap 12 and the shell 13 can also be integrated. Specifically, the end cap 12 and the shell 13 can form a common connection surface before other components are put into the shell, and when the interior of the shell 13 needs to be encapsulated, the end cap 12 covers the shell 13. The shell 13 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 13 can be determined according to the specific shape and size of the battery cell assembly 11. The material of the shell 13 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

The housing 13 may contain one or more battery cell assemblies 11. The portions of the positive electrode sheet and the negative electrode sheet that do not have active materials each constitute a tab 11a. The positive tab and the negative tab may be located at one end of the main body or at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tab 11a connects the electrode terminal to form a current loop.

Referring to FIG. 2 , the battery 100 includes a box body 20 and a battery cell 10, and the battery cell 10 is contained in the box body 20. The box body 20 is used to provide a storage space for the battery cell 10, and the box body 20 can adopt a variety of structures. In some embodiments, the box body 20 can include a first part 21 and a second part 22, and the first part 21 and the second part 22 cover each other, and the first part 21 and the second part 22 jointly define a storage space for accommodating the battery cell 10. The second part 22 can be a hollow structure with one end open, and the first part 21 can be a plate-like structure, and the first part 21 covers the open side of the second part 22, so that the first part 21 and the second part 22 jointly define a storage space; the first part 21 and the second part 22 can also be hollow structures with one side open, and the open side of the first part 21 covers the open side of the second part 22. Of course, the box body 20 formed by the first part 21 and the second part 22 can be in a variety of shapes, such as a cylinder, a cuboid, etc.

In the battery 100, there may be multiple battery cells 10, and the multiple battery cells 10 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 10 are both connected in series and in parallel. The multiple battery cells 10 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 10 is accommodated in the box 20; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 10 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 20. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 10.

The battery 100 in the embodiment of the present application includes a lithium-ion battery as a battery cell 10. In other embodiments, the battery 100 may further include any one or more of a lithium-sulfur battery, a sodium-ion battery, and a magnesium-ion battery, but is not limited thereto. The battery cell 10 may be cylindrical, flat, rectangular, or in other shapes.

In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

In addition, the present application also provides an electrical device, the electrical device comprising the battery cell and/or the battery provided in the present application. At least one. A battery cell or battery pack can be used as a power source for an electrical device or as an energy storage unit for an electrical device. Electrical devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as 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., but are not limited thereto.

As an electrical device, a battery cell and/or a battery can be selected according to its usage requirements.

As shown in FIG3 , the electric device is a vehicle such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. A schematic diagram of the partial structure of an electric device of an embodiment is specifically provided. A battery 100 is arranged inside the electric device 1000, and the battery 100 can be arranged at the bottom, head, or tail of the electric device 1000. The battery 100 can be used to power the electric device 1000. For example, the battery 100 can be used as an operating power source for the electric device 1000. The electric device 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for the starting, navigation, and driving power requirements of the electric device 1000.

In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the electrical device 1000, but also serve as a driving power source for the electrical device 1000, replacing or partially replacing fuel or natural gas to provide driving power for the electrical device 1000.

Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

Example 1

1) Preparation of positive electrode active material composition:

1.1) Preparation of positive electrode active material precursor: Nickel sulfate, manganese sulfate and cobalt sulfate are prepared into a 1 mol/L solution by molar ratio, and the precursor nickel cobalt manganese hydroxide is prepared by hydroxide coprecipitation technology. The precursor nickel cobalt manganese hydroxide product is controlled by controlling the molar ratio of nickel sulfate, manganese sulfate and cobalt sulfate. Specifically, the precursors Ni _0.55 Co _0.05 Mn _0.40 (OH) ₂ , Ni _0.55 Co _0.12 Mn _0.33 (OH) ₂ and Ni _0.55 Co _0.15 Mn _0.30 (OH) ₂ are obtained.

1.2) Preparation of the first lithium nickel cobalt manganese oxide: Precursor Ni _0.55 Co _0.05 Mn _0.40 (OH) ₂ and lithium carbonate containing Li compound were mixed at a molar ratio of 1:1.07, and then sintered at 900°C, and mechanically ground after cooling to obtain lithium nickel cobalt manganese oxide A. The lithium nickel cobalt manganese oxide A was mixed with 600ppm Al ₂ O ₃ and 1000ppm ZrO ₂ , and then sintered at 400°C to form a coating layer of Al ₂ O ₃ and ZrO ₂ on the surface of the lithium nickel cobalt manganese oxide, thereby obtaining a surface-modified single crystal first lithium nickel cobalt manganese oxide. Specifically as shown in Figure 4, the first lithium nickel cobalt manganese oxide LiNi _0.55 Co _0.05 Mn _0.40 O ₂ /Al ₂ O ₃ /ZrO ₂ has a volume average particle size Dv50 of 3 μm, a volume distribution particle size Dv10 of 2 μm, a volume distribution particle size Dv90 of 10 μm, and a volume distribution particle size Dv99 of 16 μm. In other embodiments, the volume distribution particle size Dv10 may also be 1-3 μm, the volume distribution particle size Dv90 of 6-11 μm, and the volume distribution particle size Dv99 of 10-17 μm.

1.3) Preparation of the second lithium nickel cobalt manganese oxide: The above-mentioned precursor Ni _0.55 Co _0.12 Mn _0.33 (OH) ₂ and the lithium-containing compound lithium carbonate are mixed at a molar ratio of 1:1.05, and then sintered at 850°C, cooled, and ground to obtain a single crystal lithium nickel cobalt manganese oxide B. The above-mentioned single crystal lithium nickel cobalt manganese oxide B is mixed with 600ppm Al ₂ O ₃ and 1000ppm WO ₃ , and then sintered at 450°C to form a coating layer of Al ₂ O ₃ and WO ₃ on the surface of the lithium nickel cobalt manganese oxide, so as to obtain a surface-modified second lithium nickel cobalt manganese oxide. The second lithium nickel cobalt manganese oxide LiNi _0.55 Co _0.12 Mn _0.33 O ₂ /Al ₂ O ₃ /WO ₃ , as shown in Figure 5, has a volume average particle size Dv50 of 2.1 μm, a volume distribution particle size Dv10 of 2 μm, a volume distribution particle size Dv90 of 8 μm, and a volume distribution particle size Dv99 of 10 μm. In other embodiments, the volume distribution particle size Dv10 may also be 1-3 μm, the volume distribution particle size Dv90 of 4-10 μm, and the volume distribution particle size Dv99 of 4-12 μm.

1.4) Preparation of the third lithium nickel cobalt manganese oxide: The above-mentioned precursor Ni _0.55 Co _0.15 Mn _0.30 (OH) ₂ and the lithium-containing compound lithium carbonate are mixed at a molar ratio of 1:1.07, and then sintered at 800°C, cooled, and ground to obtain a single crystal lithium nickel cobalt manganese oxide C. The above-mentioned single crystal lithium nickel cobalt manganese oxide C is mixed with 1200ppm Al ₂ O ₃ , 1000ppm Sb ₂ O ₅ , and 1000ppm ZrO ₂ , and then sintered at 450°C to form a coating layer of Al ₂ O ₃ , Sb ₂ O ₅ and ZrO ₂ on the surface of the lithium nickel cobalt manganese oxide, so as to obtain a surface-modified single crystal third lithium nickel cobalt manganese oxide with a volume average particle size Dv50 of 2μm. The third lithium nickel cobalt manganese oxide LiNi _0.55 Co _0.15 Mn _0.30 O ₂ /Sb ₂ O ₅ /ZrO ₂ , the volume distribution particle size Dv10 is 2μm, the volume distribution particle size Dv90 is 8μm, and the volume distribution particle size Dv99 is 10μm. In other embodiments, the volume distribution particle size Dv10 may also be 1-3μm, the volume distribution particle size Dv90 is 4-10μm, and the volume distribution particle size Dv99 is 4-12μm.

1.5) The first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide, and the third lithium nickel cobalt manganese oxide are mixed in a mass ratio of 48:12:40 to obtain a positive electrode active material composition.

The present application does not limit the preparation method of the positive electrode active material precursor, the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide. In other embodiments, other preparation methods may be used, or the existing first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide may be used.

2) Preparation of positive electrode.

The positive electrode active material composition, conductive carbon black SP and binder polyvinylidene fluoride (PVDF) prepared above are dispersed in a solvent N,N-dimethylpyrrolidone (NMP) at a weight ratio of 98:1:1 and mixed evenly to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet is obtained.

3) Preparation of negative electrode materials.

The negative electrode active material graphite, the thickener sodium carboxymethyl cellulose, the binder styrene butadiene rubber, and the conductive agent acetylene black are mixed in a mass ratio of 97:1:1:1, and deionized water is added to obtain a negative electrode slurry under the action of a vacuum mixer; the negative electrode slurry is evenly coated on a copper foil; the copper foil is dried at room temperature and then transferred to a 120°C oven for drying for 1 hour, and then supercooled pressed and cut to obtain a negative electrode sheet.

4) Preparation of electrolyte.

The organic solvent is a mixed solution containing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), wherein the volume ratio of EC, EMC and DEC is 20:20:60. In an argon atmosphere glove box with a water content of <10ppm, fully dried lithium salt is dissolved in the organic solvent and mixed evenly to obtain an electrolyte. The concentration of the lithium salt is 1 mol/L.

5) Isolation film.

A 12μm thick polypropylene isolation film was selected.

6) Preparation of lithium-ion batteries.

The positive electrode sheet, isolation film and negative electrode sheet are stacked in order, so that the isolation film is placed between the positive and negative electrode sheets to play an isolating role. Then, they are wound into a square bare battery cell, loaded with aluminum-plastic film, and then baked at 80°C to remove water. Then, the corresponding non-aqueous electrolyte is injected and sealed. After standing, hot and cold pressing, formation, clamping, capacity division and other processes, the finished battery is obtained.

7)Performance testing.

7.1) Test of compaction density.

1) Take a cathode active material composition powder with a mass of m and place it in a compaction density test mold. The cross-sectional area S of the mold containing the powder is 1.37 cm ² ; place the mold in a compaction density instrument UTM7305 of Shenzhen Sansi Zongheng, set the pressure to 2.94×10 ⁴ N, and test the thickness h of the powder under the pressure. The compaction density can be calculated by ρ=m/v=m/(s·h).

7.2) Volume distribution particle size test.

Equipment model: Malvern 3000 (MasterSizer 3000) laser particle size analyzer, reference standard process: GB/T19077-2016/ISO 13320:2009, specific test process: take an appropriate amount of sample to be tested (the sample concentration is guaranteed to be 8-12% shading), add 20ml of deionized water, and simultaneously ultraviolet for 5min (53KHz/120W) to ensure that the sample is completely dispersed, and then measure the sample according to GB/T19077-2016/ISO 13320:2009 standard.

7.3) Energy density test.

At 25°C, charge the lithium-ion battery to 4.5V at 1A constant current, then charge at constant voltage until the current is less than 0.5A. Then discharge the battery to 2.8V at 1A constant current, then discharge to 2.8V at 0.5A constant current, and finally discharge to 2.8V at 0.1A. Record the discharge capacity C (Ah) of the battery, and record the voltage value U (V) of the battery when the discharge reaches half of the capacity. At this time, weigh the battery and record the mass m ₀ (kg). Battery energy W = C × U, battery energy density = W/m ₀ .

7.4) Specific surface area test.

The specific surface area SSA of the positive electrode active material composition refers to GB/T 19587-2017 "Gas adsorption BET method to test the specific surface area of solid substances" and is tested using a specific surface area tester (such as TriStarⅡ3020) at a constant temperature and low temperature. After calculating the adsorption amount of gas on the solid surface at different relative pressures, the monolayer adsorption amount of the sample is obtained based on the Brownauer-Etter-Taylor (BET) multilayer adsorption theory, thereby calculating the specific surface area of the solid.

The cathode material compositions, processes and performance parameters of other embodiments and comparative examples are detailed in Table 1 and Table 2. The testing processes of other embodiments and comparative examples are the same as above.

Table 1 Positive electrode material compositions and parameters of various embodiments and comparative examples.

Table 2 Process and performance parameters of the positive electrode material compositions of various embodiments and comparative examples.


Note: The mass ratio of the first to the second represents the mass ratio of the first lithium nickel cobalt manganese oxide to the second lithium nickel cobalt manganese oxide; the total mass ratio of the first to the second represents the ratio of the sum of the masses of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide to the total mass of the positive electrode active material composition; the DV50 ratio represents the ratio of the volume average particle diameter DV50 of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide; the specific surface area represents the specific surface area of the positive electrode active material composition.

According to the test results in Table 1 and Table 2, the positive electrode active material compositions of Examples 1 to 13 are mixed by mixing three lithium nickel cobalt manganese oxides with different volume average particle sizes Dv50. Compared with Comparative Examples 3 to 5, which are mixed by mixing two lithium nickel cobalt manganese oxides with different volume average particle sizes Dv50, the specific surface area of the positive electrode active material compositions of Examples 1 to 13 of the present application is reduced, which can reduce the side reactions during the battery cycle; the compaction density is increased, and the energy density is increased. Based on Comparative Examples 1 and 2, the positive electrode active material compositions of Examples 1 to 13 are mixed by using three lithium nickel cobalt manganese oxides with different volume average particle sizes Dv50, and the ratio of the volume average particle sizes Dv50 of the three lithium nickel cobalt manganese oxides is controlled within the range of (3-2.2): (2.1-1.5): 1, so that the specific surface area of the positive electrode active material composition is reduced, the compaction density is increased, and the energy density is increased.

In the embodiment of the present application, the energy density of the battery is enhanced and has good electrical performance by controlling the mass ratio of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide to be (4-5): 1. The total mass ratio of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is controlled to be 60%-90%, so that the energy density of the battery is enhanced and has good electrical performance.

It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims (15)

A lithium-ion secondary battery, comprising a positive electrode plate, wherein the positive electrode plate comprises a positive electrode active material composition, and the positive electrode active material composition comprises: A first lithium nickel cobalt manganese oxide, a second lithium nickel cobalt manganese oxide and a third lithium nickel cobalt manganese oxide with a volume average particle size Dv50 ranging from 1 μm to 8.8 μm, wherein the volume average particle size Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is (3-2.2):(2.1-1.5):1; The volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 3 μm-8.8 μm; The volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 2 μm-8 μm; The volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1 μm-4 μm. The lithium-ion secondary battery according to claim 1, wherein the volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 4 μm-6 μm; or/and, The volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 3 μm-5 μm; or/and, The volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1.5 μm-3 μm. The lithium-ion secondary battery according to claim 1, wherein the mass ratio of the first lithium nickel cobalt manganese oxide to the second lithium nickel cobalt manganese oxide is (2.5-5):1. The positive electrode active material composition according to claim 1 or 3, wherein the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is 60%-97.6% based on the total mass of the positive electrode active material composition. The lithium ion secondary battery according to any one of claims 1 to 3, wherein the first lithium nickel cobalt manganese oxide comprises a material having a chemical formula of Li _x1 (Ni _a1 Co _b1 Mn _c1 ) _d1 M _1-d1 O _y1 Az ₁ , the second lithium nickel cobalt manganese oxide comprises a material having a chemical formula of Li _x2 (Ni _a2 Co _b2 Mn _c2 ) _d2 M _1-d2 O _y2 A _z2 , and the third lithium nickel cobalt manganese oxide comprises a material having a chemical formula of Li _x3 (Ni _a3 Co _b3 Mn _c3 ) _d3 M _1-d3 O _y3 A _z3 , wherein 0.95≤x1≤1.1, 0.3≤a1≤0.7, 0.01≤b1≤0.15, 0.15≤c1≤0.55, a1+b1+c1＝1, 0.95≤d1≤1, 1.9≤y1≤2.1, 0≤z1≤0.1; 0.95≤x2≤1.1, 0.3≤a2≤0.7, 0.01≤b2≤0.15, 0.15≤c2≤0.55, a2+b2+c2＝1, 0.95≤d2≤1, 1.9 ≤y2≤2.1, 0≤z2≤0.1; 0.95≤x3≤1.3, 0.3≤a3≤0.7, 0.06≤b3≤0.20, 0.1≤c3≤0.5, a3+b3+c3＝1, 0.95≤d3≤1, 1.9≤y3≤2.1, 0≤z3≤0.1; M includes one or more of Zr, Sr, B, Ti, Mg, Sn, Mo, W, Sb, Nb, La and Al, and A includes one or more of S, N, F, Cl, Br and I. The lithium ion secondary battery according to claim 5, wherein the ratio of b1:b2:b3 is 1:(0.5-3):(1-4). The lithium ion secondary battery according to any one of claims 1 to 3, wherein, under a pressure of 2.94×10 ⁴ N, the compaction density of the positive electrode active material composition is 3 g/cm ³ -4 g/cm ³ . The lithium ion secondary battery according to any one of claims 1 to 3, wherein the positive electrode active material composition has a specific surface area of 0.6 m ² /g to 1.0 ^{m 2} /g. The lithium-ion secondary battery according to any one of claims 1 to 3, wherein the volume distribution particle size Dv10 of the first lithium nickel cobalt manganese oxide is 1 μm-3 μm, the volume distribution particle size Dv90 is 6 μm-11 μm, and the volume distribution particle size Dv99 is 10 μm-17 μm; or/and, The volume distribution particle size Dv10 of the second lithium nickel cobalt manganese oxide is 1 μm-3 μm, the volume distribution particle size Dv90 is 4 μm-10 μm, and the volume distribution particle size Dv99 is 4 μm-12 μm; or/and, The volume distribution particle size Dv10 of the third lithium nickel cobalt manganese oxide is 1 μm-2 μm, the volume distribution particle size Dv90 is 3 μm-6 μm, and the volume distribution particle size Dv99 is 4 μm-8 μm. The lithium-ion secondary battery according to any one of claims 1 to 3, wherein the crystals of one or more of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide are single crystals. A positive electrode active material composition, comprising: The first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the first lithium nickel cobalt manganese oxide have a volume average particle size Dv50 in the range of 1 μm to 8.8 μm. Three lithium nickel cobalt manganese oxides, wherein the volume average particle diameter Dv50 ratio of the first lithium nickel cobalt manganese oxide, the second lithium nickel cobalt manganese oxide and the third lithium nickel cobalt manganese oxide is (3-2.2):(2.1-1.5):1; The volume average particle size Dv50 of the first lithium nickel cobalt manganese oxide is 3 μm-8.8 μm; The volume average particle size Dv50 of the second lithium nickel cobalt manganese oxide is 2 μm-8 μm; The volume average particle size Dv50 of the third lithium nickel cobalt manganese oxide is 1 μm-4 μm. The positive electrode active material composition according to claim 1, wherein the mass ratio of the first lithium nickel cobalt manganese oxide to the second lithium nickel cobalt manganese oxide is (2.5-5):1. The positive electrode active material composition according to claim 1 or 3, wherein the sum of the mass proportions of the first lithium nickel cobalt manganese oxide and the second lithium nickel cobalt manganese oxide is 60%-97.6% based on the total mass of the positive electrode active material composition. A positive electrode sheet, comprising the positive electrode active material composition according to any one of claims 11 to 13. An electrical device, comprising the lithium ion secondary battery according to any one of claims 1 to 10, or/and the positive electrode active material composition according to any one of claims 11 to 13, or/and the positive electrode sheet according to claim 14.