A positive electrode material

Abstract

The application discloses a kind of positive electrode materials, the positive electrode material includes several secondary particles, the secondary particle is composed of primary particle, the maximum groove depth of single secondary particle that constitutes positive electrode material is d, the spherical diameter of single secondary particle that constitutes positive electrode material is D, the average groove depth of single secondary particle that constitutes positive electrode material is m, the maximum groove depth d of single secondary particle and the spherical diameter D of single secondary particle satisfy 0.001≤d / D≤0.08;The average groove depth m of single secondary particle and the spherical diameter D of single secondary particle satisfy 0.001≤m / D≤0.05.The beneficial effects of the present application are: the primary particles contained in the positive electrode material of the application are arranged uniformly, and the depth of the groove of the secondary particle surrounded by the primary particles is relatively shallow, so that the positive electrode material has strong pressure resistance, thereby enhancing the cycle performance of the battery, reducing the occurrence of side reactions, ensuring the stability of the positive electrode material, and increasing the safety of battery use.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a positive electrode material. Background Art

[0002] Secondary particles in nickel-cobalt-manganese materials are composed of multiple primary particles, forming spherical particles. The arrangement and composition of the primary particles significantly influence the structure of the secondary spheres; the stability of the secondary particles also significantly impacts the battery's cycling performance and safety. Poor primary particle arrangement reduces the material's compaction density, which in turn reduces the battery's energy density. Furthermore, low compaction density increases electrolyte penetration and side reactions, further deteriorating the battery's cycling performance. Summary of the Invention

[0003] The main purpose of the present application is to provide a positive electrode material in which the primary particles constituting the secondary particles are arranged more uniformly.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A positive electrode material comprises a plurality of secondary particles, wherein the secondary particles are composed of primary particles, the maximum groove depth of a single secondary particle constituting the positive electrode material is d, the spherical diameter of a single secondary particle constituting the positive electrode material is D, the average groove depth of the single secondary particles constituting the positive electrode material is m, the maximum groove depth d of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.001≤d / D≤0.08; and the average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.001≤m / D≤0.05.

[0006] Excessively deep grooves in the individual secondary particles that make up the positive electrode material can easily cause cracking during cold pressing. This can also lead to uneven stress release during charge and discharge cycles, causing cracking and impacting battery performance. Furthermore, cracking in the positive electrode can exacerbate side reactions, further increasing the risk of gassing and potentially posing a safety hazard.

[0007] The average grooves of the secondary particles reflect the uniformity of the arrangement of the primary particles that make up the secondary particles, and also reflect the voltage resistance of the positive electrode material. The smaller the average grooves, the more uniform the arrangement of the primary particles that make up the secondary particles.

[0008] When the maximum groove depth and the average groove depth of the secondary particles of the positive electrode material are closer, it means that the structure of the positive electrode material is more uniform and the overall stress-bearing performance is better.

[0009] The test method for the maximum groove d is as follows: cross-section the secondary particle and magnify it by a certain multiple to achieve a single secondary particle in the entire image. The most prominent point of the two primary particles connected on the surface is the distance d from the groove between the two primary particles to the connecting line.

[0010] D is the mean of the major and minor axes of the secondary particles;

[0011] The average groove depth is measured for a single secondary particle, all grooves are measured and the average value is taken as m1 (no groove between two primary particles is not included in the statistics), and 30 or more secondary particles are measured, and the corresponding average value is m.

[0012] The above-mentioned positive electrode material, as a preferred embodiment, the maximum groove depth d of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.003≤d / D≤0.05; preferably, the maximum groove depth d of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.005≤d / D≤0.03.

[0013] In the above-mentioned positive electrode material, as a preferred embodiment, the average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.002≤m / D≤0.02.

[0014] In the above-mentioned positive electrode material, as a preferred embodiment, the relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is 1≤d / m≤5, preferably, 1.5≤d / m≤3.

[0015] In the above-mentioned positive electrode material, as a preferred embodiment, the maximum groove depth of the secondary particles is 0.2-1.2 μm, preferably 0.3-0.8 μm.

[0016] In the above-mentioned positive electrode material, as a preferred embodiment, the angles occupied by the two primary particles that form the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively, and the value of α is: 0<α≤30°, and the value of β is 0<β≤30°;

[0017] α is the angle between two tangent lines drawn from the center of the secondary particle to one of the primary particles that forms the maximum groove depth of the secondary particle;

[0018] β is the angle between two tangent lines drawn from the center of the secondary particle to another primary particle that forms the maximum groove depth of the secondary particle.

[0019] The above-mentioned positive electrode material, as a preferred embodiment, has a cross-section of the primary particles surrounding the surface of a single secondary particle (the cross-section is a cross-section obtained by cutting the secondary sphere) that is arc-shaped, and the arc angle of the largest primary particle surrounding the surface of the single secondary particle is γ, and the γ value is: 20°≤γ≤130°, preferably, the γ value is: 30°≤γ≤110°; more preferably, the γ value is: 45°≤γ≤90°;

[0020] γ is the fullness of the primary particles.

[0021] As a preferred embodiment, the above-mentioned positive electrode material has the general formula:

[0022] Li 1+a [Ni x Co y M z M1 b ]O2, of which 0.5 <x<1,0<y<0.3,0<z<0.3,0<a<0.2,0<b;

[0023] Wherein, M is one or two of Mn and / or Al; M1 is one or more of Zr, Mg, Ti, Te, Al, Ca, Sr, Sb, Nb, Pb, V, Ge, Se, W, Mo, Zn, and Ce.

[0024] The beneficial effects of the present invention are as follows: the primary particles contained in the positive electrode material of the present invention are arranged evenly, and the depth of the secondary particle grooves surrounded by the primary particles is shallow, so that the positive electrode material has strong pressure resistance, thereby enhancing the cycle performance of the battery.

[0025] The maximum groove depth and average groove depth of the secondary particles of the positive electrode material described in the present invention are relatively close, that is, the structure of the positive electrode material described in the present application is relatively uniform, the overall stress-bearing performance is relatively good, and no cracking will occur when subjected to stress, thereby reducing the occurrence of side reactions and increasing the safety of battery use.

[0026] The particles of the positive electrode material of the present invention have relatively large accumulated stress and are subjected to relatively uniform stress, which further reduces the cracking of the positive electrode material caused by stress and ensures the stability of the positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a cross-sectional scan of the positive electrode material described in Example 17 and a schematic diagram of angles α, β and γ. DETAILED DESCRIPTION

[0028] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to examples. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0029] The present application describes a positive electrode material, wherein the positive electrode material includes a plurality of secondary particles, wherein the secondary particles are composed of primary particles, the maximum groove depth of a single secondary particle constituting the positive electrode material is d, the spherical diameter of a single secondary particle constituting the positive electrode material is D, and the average groove depth of the single secondary particles constituting the positive electrode material is m;

[0030] The maximum groove depth d of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.001≤d / D≤0.08;

[0031] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.001≤m / D≤0.05; the relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is 1≤d / m≤5;

[0032] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively, and the value of α is: 0<α≤30°, and the value of β is 0<β≤30°;

[0033] Where: α is the angle between two tangent lines drawn from the center of the secondary particle to one of the primary particles with the maximum groove depth of the secondary particle;

[0034] β is the angle between two tangent lines drawn from the center of the secondary particle to another primary particle that forms the maximum groove depth of the secondary particle.

[0035] The cross section of the primary particles surrounding the surface of a single secondary particle is arc-shaped, and the arc angle of the largest primary particle surrounding the surface of the single secondary particle is γ, and the γ value is: 20°≤γ≤130°.

[0036] The testing method for the performance parameters of the positive electrode material described in the embodiment of this application is:

[0037] (1) The test method for the capacity retention rate after 300 cycles of high temperature cycling is:

[0038] The positive electrode material is coated into a pole piece, the negative electrode is made of graphite, and is composed of a polyethylene separator and an electrolyte (the electrolyte is LiPF6 and the solvent is EC / DMC) to form a battery. Under the condition of charge and discharge at a rate of 1C, the battery is cycled, and the capacity of each cycle is compared with the capacity of the first cycle to confirm the capacity retention rate. At 45°C, the capacity retention rate is calculated after 300 cycles.

[0039] (2) Test method for 300-cycle DCR growth:

[0040] 300-week DCR growth rate = (300th week DCR value - 1st week DCR value) / 1st week DCR value × 100%.

[0041] DCR = (V1-V2) / I1C, V1 is the static voltage before 1C discharge, V2 is the voltage after 1C discharge for 30 seconds, and I1C is the constant current of 1C.

[0042] (3) 7D gas production test method:

[0043] The battery assembled above (the battery assembled in step (1)) was fully charged at a rate of 1C to the cut-off voltage at 25°C, and then charged at a constant voltage at the cut-off voltage until the current was less than 0.05C.

[0044] The volume of the fully charged battery before storage is tested and recorded as V0;

[0045] Place the fully charged battery in a 70±2°C oven. After 7 days, remove the battery and immediately measure its post-storage volume, which is recorded as V1.

[0046] 7D gas production: (V1-V0) / V0×100%.

[0047] (4) Maximum compaction test method

[0048] Prepare the electrode and cut it. By adjusting the rolling pressure, press the positive electrode to a certain thickness. Fold the rolled electrode in half and then unfold it. Observe in a lighted place whether the fold is light-transmitting. If it is not light-transmitting or a break occurs, adjust the pressure again until it is just light-transmitting. The maximum compaction is calculated at this time.

[0049] The preparation method of the positive electrode material described in this application is as follows:

[0050] S1: placing the precursor particles, the lithium source, and the dopant (the doping element used in Example 1 is Nb) in a device and mixing them uniformly to obtain a first mixture;

[0051] S2: sintering the first mixture in an oxidizing atmosphere to obtain a first sintered product;

[0052] S3: crushing the first sintered product, washing it with water, and drying it to obtain a dried product;

[0053] S4: directly placing the dried product in a furnace and sintering it in an oxidizing atmosphere to obtain a second sintered product.

[0054] Example 1

[0055] The positive electrode material described in Example 1 includes a plurality of secondary particles, each of which is composed of primary particles. The maximum groove depth of a single secondary particle constituting the positive electrode material is d, the spherical diameter of a single secondary particle constituting the positive electrode material is D, and the average groove depth of the single secondary particles constituting the positive electrode material is m. The maximum groove depth d of a single secondary particle and the spherical diameter D of a single secondary particle satisfy a relationship d / D of 0.01; the average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy a relationship m / D of 0.005. The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m of 2.

[0056] The maximum groove depth of the secondary particle can be 0.6um, and the angles occupied by the two primary particles that form the maximum groove depth of a single secondary particle in the secondary particle are α and β respectively, the value of α is 15°, and the value of β is 10°; α is the angle between two tangents drawn from the center of the secondary particle to one of the primary particles that form the maximum groove depth of the secondary particle; β is the angle between two tangents drawn from the center of the secondary particle to the other primary particle that forms the maximum groove depth of the secondary particle.

[0057] The cross section of the primary particles surrounding the surface of a single secondary particle is arc-shaped, and the arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, the γ value is: 95°, and γ is: the fullness of the primary particle.

[0058] The structural formula of the positive electrode material obtained in Example 1 is: LiNi 0.8 Co 0.1 Mn 0.08 Nb 0.02 O2.

[0059] Example 2

[0060] The difference between the positive electrode material described in Example 2 and the positive electrode material described in Example 1 is that:

[0061] The maximum groove depth of the secondary particles described in Example 2 is 0.2 μm;

[0062] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 2 and the spherical diameter D of a single secondary particle satisfy d / D=0.001;

[0063] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.001;

[0064] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 1;

[0065] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 20° and the value of β is 18°.

[0066] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 89°.

[0067] Example 3

[0068] The difference between the positive electrode material described in Example 3 and the positive electrode material described in Example 1 is that:

[0069] The maximum groove depth of the secondary particles described in Example 3 is 0.4 μm;

[0070] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 3 and the spherical diameter D of a single secondary particle satisfy d / D=0.003;

[0071] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.001;

[0072] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 3;

[0073] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 22° and the value of β is 16°.

[0074] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 88°.

[0075] Example 4

[0076] The difference between the positive electrode material described in Example 4 and the positive electrode material described in Example 1 is that:

[0077] The maximum groove depth of the secondary particles described in Example 4 is 0.6 μm;

[0078] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 4 and the spherical diameter D of a single secondary particle satisfy d / D=0.005;

[0079] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.002;

[0080] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m is 2.5;

[0081] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 18° and the value of β is 15°.

[0082] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 80°.

[0083] Example 5

[0084] The difference between the positive electrode material described in Example 5 and the positive electrode material described in Example 1 is that:

[0085] The maximum groove depth of the secondary particles described in Example 5 is 0.8 μm;

[0086] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 5 and the spherical diameter D of a single secondary particle satisfy d / D=0.08;

[0087] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.03;

[0088] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 2.7;

[0089] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 17° and the value of β is 16°.

[0090] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 92°.

[0091] Example 6

[0092] The difference between the positive electrode material described in Example 6 and the positive electrode material described in Example 1 is that:

[0093] The maximum groove depth of the secondary particles described in Example 6 is 0.4 μm;

[0094] The maximum groove depth d of a single secondary particle of the positive electrode material described in Example 6 and the spherical diameter D of a single secondary particle satisfy d / D=0.02;

[0095] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.01;

[0096] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0097] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 14° and the value of β is 16°.

[0098] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 85°.

[0099] Example 7

[0100] The difference between the positive electrode material described in Example 7 and the positive electrode material described in Example 1 is that:

[0101] The maximum groove depth of the secondary particles described in Example 7 is 0.7 μm;

[0102] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 7 and the spherical diameter D of a single secondary particle satisfy d / D=0.03;

[0103] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0104] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.5;

[0105] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 13° and the value of β is 18°.

[0106] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 88°.

[0107] Example 8

[0108] The difference between the positive electrode material described in Example 8 and the positive electrode material described in Example 1 is that:

[0109] The maximum groove depth of the secondary particles described in Example 8 is 1.2 μm;

[0110] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 8 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0111] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0112] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0113] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 16°, and the value of β is 16°.

[0114] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 79°.

[0115] Example 9

[0116] The difference between the positive electrode material described in Example 9 and the positive electrode material described in Example 1 is that:

[0117] The maximum groove depth of the secondary particles described in Example 9 is 0.8 μm;

[0118] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 9 and the spherical diameter D of a single secondary particle satisfy d / D=0.05;

[0119] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0120] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m is 2.5;

[0121] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 20° and the value of β is 13°.

[0122] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 91°.

[0123] Example 10

[0124] The difference between the positive electrode material described in Example 10 and the positive electrode material described in Example 1 is that:

[0125] The maximum groove depth of the secondary particles described in Example 10 is 1.0 μm;

[0126] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 10 and the spherical diameter D of a single secondary particle satisfy d / D=0.06;

[0127] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.015;

[0128] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 4;

[0129] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 19° and the value of β is 17°.

[0130] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 86°.

[0131] Example 11

[0132] The positive electrode material described in Example 11 differs from the positive electrode material described in Example 1 in that:

[0133] The maximum groove depth of the secondary particles described in Example 11 is 1.0 μm;

[0134] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 11 and the spherical diameter D of a single secondary particle satisfy d / D=0.07;

[0135] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.04;

[0136] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.75;

[0137] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 16° and the value of β is 17°.

[0138] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 84°.

[0139] Example 12

[0140] The difference between the positive electrode material described in Example 12 and the positive electrode material described in Example 1 is that:

[0141] The maximum groove depth of the secondary particles described in Example 12 is 0.4 μm;

[0142] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 12 and the spherical diameter D of a single secondary particle satisfy d / D=0.08;

[0143] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.05;

[0144] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.6;

[0145] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 13° and the value of β is 18°.

[0146] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 93°.

[0147] The properties of the positive electrode materials described in Examples 1-12 are shown in Table 1:

[0148] Table 1

[0149]

[0150]

[0151] It can be seen from Table 1 that: as d / D increases, the maximum compaction decreases (specifically, Example 1, Example 5, and Example 9 can be compared); the cycle performance will first increase and then decrease, specifically it will be better at 0.01, and then the cycle performance will decrease, which can be specifically compared (Example 1, Example 2, Example 3, Example 5 groups); the 7D gas production and 300-cycle DCR growth will gradually increase with the increase of d / D; compared with Example 5 and Example 12, the smaller the m / D, the lower the 7D gas production and 300-cycle DCR growth will be.

[0152] Example 13

[0153] The difference between the positive electrode material described in Example 13 and the positive electrode material described in Example 1 is that:

[0154] The maximum groove depth of the secondary particles described in Example 13 is 0.4 μm.

[0155] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 13 and the spherical diameter D of a single secondary particle satisfy d / D=0.01;

[0156] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.005;

[0157] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0158] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively, and the value of α is 30° and the value of β is 30°;

[0159] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 84°.

[0160] Example 14

[0161] The difference between the positive electrode material described in Example 14 and the positive electrode material described in Example 13 is that:

[0162] The maximum groove depth of the secondary particles described in Example 14 can be 0.6 μm;

[0163] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively, with the value of α being 10° and the value of β being 9°;

[0164] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 83°.

[0165] Example 15

[0166] The difference between the positive electrode material described in Example 15 and the positive electrode material described in Example 13 is that:

[0167] The maximum groove depth of the secondary particles described in Example 15 can be 0.7 μm;

[0168] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively, with the value of α being 10° and the value of β being 30°;

[0169] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 89°.

[0170] Example 16

[0171] The difference between the positive electrode material described in Example 16 and the positive electrode material described in Example 13 is that:

[0172] The maximum groove depth of the secondary particles described in Example 16 can be 0.8 μm;

[0173] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively, with the value of α being 10° and the value of β being 20°;

[0174] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 80°.

[0175] Example 17

[0176] The difference between the positive electrode material described in Example 17 and the positive electrode material described in Example 13 is that:

[0177] The maximum groove depth of the secondary particles described in Example 17 can be 0.8 μm;

[0178] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 7° and the value of β is 9°.

[0179] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 88°.

[0180] Example 18

[0181] The difference between the positive electrode material described in Example 18 and the positive electrode material described in Example 13 is that:

[0182] The maximum groove depth of the secondary particles described in Example 18 can be 0.6 μm;

[0183] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 12° and the value of β is 17°.

[0184] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 20°.

[0185] Example 19

[0186] The difference between the positive electrode material described in Example 19 and the positive electrode material described in Example 13 is that:

[0187] The maximum groove depth of the secondary particles described in Example 19 can be 1.0 μm;

[0188] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 16° and the value of β is 14°.

[0189] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 30°.

[0190] Example 20

[0191] The difference between the positive electrode material described in Example 20 and the positive electrode material described in Example 13 is that:

[0192] The maximum groove depth of the secondary particles described in Example 20 can be 0.7 μm;

[0193] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 19° and the value of β is 16°.

[0194] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 45°.

[0195] Example 21

[0196] The difference between the positive electrode material described in Example 21 and the positive electrode material described in Example 13 is that:

[0197] The maximum groove depth of the secondary particles described in Example 21 can be 0.8 μm;

[0198] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 21° and the value of β is 16°.

[0199] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 130°.

[0200] Example 22

[0201] The difference between the positive electrode material described in Example 22 and the positive electrode material described in Example 13 is that:

[0202] The maximum groove depth of the secondary particles described in Example 22 can be 0.5 μm;

[0203] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 19° and the value of β is 18°.

[0204] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 120°.

[0205] Example 23

[0206] The difference between the positive electrode material described in Example 23 and the positive electrode material described in Example 13 is that:

[0207] The maximum groove depth of the secondary particles described in Example 23 can be 0.6 μm;

[0208] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 22° and the value of β is 14°.

[0209] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 73°.

[0210] The properties of the positive electrode materials described in Examples 13-23 of the present application are shown in Table 2:

[0211] Table 2

[0212]

[0213] Table 2 shows that as the α and β angles increase, the 300-cycle high-temperature capacity retention decreases from Examples 13 to 17. In particular, from Examples 14 to 16, a larger β angle decreases the 300-cycle high-temperature capacity retention. From Examples 16 and 18 to 23, it can be seen that as the γ angle increases, the 300-cycle DCR increases gradually.

[0214] Example 24

[0215] The difference between the positive electrode material described in Example 24 and the positive electrode material described in Example 1 is that:

[0216] The maximum groove depth of the secondary particles described in Example 24 can be 0.6 μm;

[0217] The doping element used in the positive electrode material of Example 24 is Zr;

[0218] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 24 and the spherical diameter D of a single secondary particle satisfy d / D=0.02;

[0219] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.01;

[0220] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0221] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 18° and the value of β is 20°.

[0222] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 50°.

[0223] The molecular formula of the positive electrode material in Example 24 is LiNi 0.8 Co 0.1 Mn 0.0 Zr 0.02 O2.

[0224] Example 25

[0225] The difference between the positive electrode material described in Example 25 and the positive electrode material described in Example 1 is that:

[0226] The maximum groove depth of the secondary particles described in Example 25 can be 0.7 μm;

[0227] The doping element used in the positive electrode material of Example 25 is Ti;

[0228] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 25 and the spherical diameter D of a single secondary particle satisfy d / D=0.03;

[0229] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0230] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.5;

[0231] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 19° and the value of β is 14°.

[0232] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 61°.

[0233] The molecular formula of the positive electrode material in Example 25 is: LiNi 0.8 Co 0.1 Mn 0.08 Ti 0.02 O2.

[0234] Example 26

[0235] The difference between the positive electrode material described in Example 26 and the positive electrode material described in Example 1 is that:

[0236] The maximum groove depth of the secondary particles described in Example 26 can be 0.6 μm;

[0237] The doping element used in the positive electrode material of Example 26 is Sr;

[0238] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 26 and the spherical diameter D of a single secondary particle satisfy d / D=0.08;

[0239] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.05;

[0240] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.6;

[0241] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 16° and the value of β is 18°.

[0242] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 64°.

[0243] The molecular formula of the positive electrode material in Example 26 is: LiNi 0.8 Co 0.1 Mn 0.08 Sr 0.02 O2.

[0244] Example 27

[0245] The difference between the positive electrode material described in Example 27 and the positive electrode material described in Example 1 is that:

[0246] The maximum groove depth of the secondary particles described in Example 27 can be 0.8 μm;

[0247] The doping element used in the positive electrode material of Example 27 is Al;

[0248] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 27 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0249] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0250] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0251] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 18° and the value of β is 21°.

[0252] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 56°.

[0253] The molecular formula of the positive electrode material in Example 27 is LiNi 0.8 Co 0.1 Mn 0.08 Al 0.02 O2.

[0254] Example 28

[0255] The difference between the positive electrode material described in Example 28 and the positive electrode material described in Example 1 is that:

[0256] The maximum groove depth of the secondary particles described in Example 28 can be 0.5 μm;

[0257] The doping element used in the positive electrode material of Example 28 is Mo;

[0258] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 28 and the spherical diameter D of a single secondary particle satisfy d / D=0.075;

[0259] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.015;

[0260] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 5;

[0261] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 21° and the value of β is 24°.

[0262] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 65°.

[0263] The molecular formula of the positive electrode material in Example 28 is LiNi 0.8 Co 0.1 Mn 0.08 Mo 0.02 O2.

[0264] The properties of the positive electrode materials described in Examples 24-28 of the present application are shown in Table 3:

[0265] Table 3

[0266]

[0267] Example 29

[0268] The difference between the positive electrode material described in Example 29 and the positive electrode material described in Example 1 is that:

[0269] The maximum groove depth of the secondary particles described in Example 29 can be 0.4 μm;

[0270] The precursor of the positive electrode material in Example 29 is Ni 0.87 Co 0.1 Mn 0.03 (OH)2;

[0271] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 29 and the spherical diameter D of a single secondary particle satisfy d / D=0.065;

[0272] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.013;

[0273] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 5;

[0274] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 17° and the value of β is 19°.

[0275] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 63°.

[0276] Example 30

[0277] The difference between the positive electrode material described in Example 30 and the positive electrode material described in Example 1 is that:

[0278] The maximum groove depth of the secondary particles described in Example 30 can be 0.2 μm;

[0279] The precursor of the positive electrode material used in Example 30 is Ni 0.9 Co 0.08 Mn 0.02 (OH)2;

[0280] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 30 and the spherical diameter D of a single secondary particle satisfy d / D=0.045;

[0281] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.015;

[0282] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 3;

[0283] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 26° and the value of β is 21°.

[0284] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 62°.

[0285] Example 31

[0286] The difference between the positive electrode material described in Example 31 and the positive electrode material described in Example 1 is that:

[0287] The maximum groove depth of the secondary particles described in Example 31 can be 0.8 μm;

[0288] The precursor of the positive electrode material used in Example 31 is Ni 0.92 Co 0.05 Mn 0.03 (OH)2;

[0289] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 31 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0290] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0291] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0292] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 19° and the value of β is 16°.

[0293] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 54°.

[0294] Example 32

[0295] The difference between the positive electrode material described in Example 32 and the positive electrode material described in Example 1 is that:

[0296] The maximum groove depth of the secondary particles described in Example 32 can be 0.6 μm;

[0297] The precursor of the positive electrode material used in Example 32 is Ni 0.94 Co 0.04 Mn 0.02 (OH)2;

[0298] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 32 and the spherical diameter D of a single secondary particle satisfy d / D=0.055;

[0299] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.011;

[0300] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 5;

[0301] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 19° and the value of β is 26°.

[0302] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 67°.

[0303] Example 33

[0304] The difference between the positive electrode material described in Example 33 and the positive electrode material described in Example 1 is that:

[0305] The maximum groove depth of the secondary particles described in Example 33 can be 0.7 μm;

[0306] The precursor of the positive electrode material used in Example 33 is Ni 0.97 Co 0.02 Mn 0.01 (OH)2;

[0307] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 33 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0308] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0309] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0310] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 21° and the value of β is 24°.

[0311] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 53°.

[0312] Example 34

[0313] The difference between the positive electrode material described in Example 34 and the positive electrode material described in Example 1 is that:

[0314] The maximum groove depth of the secondary particles described in Example 34 can be 0.6 μm;

[0315] The precursor of the positive electrode material used in Example 34 is Ni 0.51 Co 0.26 Mn 0.23 (OH)2;

[0316] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 34 and the spherical diameter D of a single secondary particle satisfy d / D=0.01;

[0317] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.005;

[0318] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0319] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 17° and the value of β is 14°.

[0320] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 65°.

[0321] Example 35

[0322] The difference between the positive electrode material described in Example 35 and the positive electrode material described in Example 1 is that:

[0323] The maximum groove depth of the secondary particles described in Example 35 can be 0.8 μm;

[0324] The precursor of the positive electrode material used in Example 35 is Ni 0.60 Co 0.21 Mn 0.18 (OH)2;

[0325] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 35 and the spherical diameter D of a single secondary particle satisfy d / D=0.01;

[0326] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.005;

[0327] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0328] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 18° and the value of β is 17°.

[0329] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 61°.

[0330] Example 36

[0331] The difference between the positive electrode material described in Example 36 and the positive electrode material described in Example 1 is that:

[0332] The maximum groove depth of the secondary particles described in Example 36 can be 0.4 μm;

[0333] The precursor of the positive electrode material used in Example 36 is Ni 0.72 Co 0.2 Mn 0.08 (OH)2;

[0334] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 36 and the spherical diameter D of a single secondary particle satisfy d / D=0.01;

[0335] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.005;

[0336] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0337] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 21° and the value of β is 16°.

[0338] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 59°.

[0339] Example 37

[0340] The difference between the positive electrode material described in Example 37 and the positive electrode material described in Example 1 is that:

[0341] The maximum groove depth of the secondary particles described in Example 37 can be 0.3 μm;

[0342] The precursor of the positive electrode material used in Example 37 is Ni 0.82 Co 0.1 Al 0.08 (OH)2;

[0343] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 37 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0344] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0345] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0346] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 7° and the value of β is 8°.

[0347] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 55°.

[0348] Example 38

[0349] The difference between the positive electrode material described in Example 38 and the positive electrode material described in Example 1 is that:

[0350] The maximum groove depth of the secondary particles described in Example 38 can be 0.4 μm;

[0351] The precursor of the positive electrode material used in Example 38 is Ni 0.61 Co 0.21 Al 0.18 (OH)2;

[0352] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 38 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0353] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0354] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0355] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 14° and the value of β is 19°.

[0356] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 60°.

[0357] Example 39

[0358] The difference between the positive electrode material described in Example 39 and the positive electrode material described in Example 1 is that:

[0359] The maximum groove depth of the secondary particles described in Example 39 can be 0.9 μm;

[0360] The precursor of the positive electrode material used in Example 39 is Ni 0.51 Co 0.26 Al 0.23 (OH)2;

[0361] The maximum groove depth d of a single secondary particle of the positive electrode material described in Example 39 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0362] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0363] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0364] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 9° and the value of β is 7°.

[0365] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 42°.

[0366] Example 40

[0367] The difference between the positive electrode material described in Example 40 and the positive electrode material described in Example 1 is that:

[0368] The maximum groove depth of the secondary particles described in Example 40 may be 1.0 μm;

[0369] The precursor of the positive electrode material in Example 40 is Ni 0.97 Co 0.02 Al 0.01 (OH)2;

[0370] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 40 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0371] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0372] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0373] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 19° and the value of β is 17°.

[0374] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 57°.

[0375] The properties of the positive electrode materials described in Examples 29 to 40 are shown in Table 4:

[0376] Table 4

[0377]

[0378]

[0379] As can be seen from Table 4, as the Ni content increases, the 300-cycle high-temperature cycle capacity retention rate gradually decreases from Example 34 to Example 36. As can be seen from Example 37 to Example 40, as the Ni content increases, the 300-cycle high-temperature cycle capacity retention rate gradually decreases.

[0380] Example 41

[0381] The difference between the positive electrode material described in Example 41 and the positive electrode material described in Example 1 is that:

[0382] The maximum groove depth of the secondary particles described in Example 41 can be 1.1 μm;

[0383] The doping elements used in the positive electrode material of Example 41 are Al and Ti;

[0384] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 41 and the spherical diameter D of a single secondary particle satisfy d / D=0.01;

[0385] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.005;

[0386] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0387] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 16° and the value of β is 19°.

[0388] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 61°.

[0389] The molecular formula of the positive electrode material in Example 41 is: LiNi 0.8 Co 0.1 Mn 0.08 Al 0.01 Ti 0.01 O2.

[0390] Example 42

[0391] The difference between the positive electrode material described in Example 42 and the positive electrode material described in Example 1 is that:

[0392] The maximum groove depth of the secondary particles described in Example 42 can be 1.2 μm;

[0393] The doping elements used in the positive electrode material of Example 42 are Al and Zr;

[0394] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 42 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0395] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0396] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0397] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 10° and the value of β is 13°.

[0398] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 90°.

[0399] The molecular formula of the positive electrode material in Example 42 is: LiNi 0.8 Co 0.1 Mn 0.08 Al 0.01 Zr 0.01 O2.

[0400] Example 43

[0401] The difference between the positive electrode material described in Example 43 and the positive electrode material described in Example 1 is that:

[0402] The maximum groove depth of the secondary particles described in Example 43 can be 0.6 μm;

[0403] The doping elements used in the positive electrode material of Example 43 are Sr and Nb;

[0404] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 43 and the spherical diameter D of a single secondary particle satisfy d / D=0.08;

[0405] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.05;

[0406] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.6;

[0407] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 18° and the value of β is 23°.

[0408] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 28°.

[0409] The molecular formula of the positive electrode material in Example 43 is: LiNi 0.8 Co 0.1 Mn 0.08 Sr 0.01 Nb 0.01 O2.

[0410] Example 44

[0411] The positive electrode material described in Example 44 differs from the positive electrode material described in Example 1 in that:

[0412] The maximum groove depth of the secondary particles described in Example 44 can be 0.7 μm;

[0413] The doping elements used in the positive electrode material of Example 44 are Sr and Ti;

[0414] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 44 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0415] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0416] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0417] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively, with the value of α being 25° and the value of β being 20°;

[0418] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 81°.

[0419] The molecular formula of the positive electrode material in Example 44 is: LiNi 0.8 Co 0.1 Mn 0.08 Sr 0.01 Ti 0.01 O2.

[0420] Example 45

[0421] The difference between the positive electrode material described in Example 45 and the positive electrode material described in Example 1 is that:

[0422] The maximum groove depth of the secondary particles described in Example 45 can be 0.6 μm;

[0423] The doping elements used in the positive electrode material of Example 45 are Mo and Nb;

[0424] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 45 and the spherical diameter D of a single secondary particle satisfy d / D=0.07;

[0425] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.05;

[0426] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.4;

[0427] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 13° and the value of β is 12°.

[0428] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 42°.

[0429] The molecular formula of the positive electrode material in Example 45 is: LiNi 0.8 Co 0.1 Mn 0.08 Nb 0.01 Mo 0.01 O2.

[0430] Example 46

[0431] The difference between the positive electrode material described in Example 46 and the positive electrode material described in Example 1 is that:

[0432] The maximum groove depth of the secondary particles described in Example 46 can be 0.4 μm;

[0433] The doping elements used in the positive electrode material of Example 46 are Al and Mo;

[0434] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 46 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0435] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.015;

[0436] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 2.7;

[0437] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 14° and the value of β is 12°.

[0438] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 37°.

[0439] The molecular formula of the positive electrode material in Example 46 is: LiNi 0.8 Co 0.1 Mn 0.08 Al 0.01 Mo 0.01 O2.

[0440] Example 47

[0441] The difference between the positive electrode material described in Example 47 and the positive electrode material described in Example 1 is that:

[0442] The maximum groove depth of the secondary particles described in Example 47 can be 0.5 μm;

[0443] The doping elements used in the positive electrode material of Example 47 are Mo and Zr;

[0444] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 47 and the spherical diameter D of a single secondary particle satisfy d / D=0.035;

[0445] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.01;

[0446] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 3.5;

[0447] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 17° and the value of β is 19°.

[0448] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 41°.

[0449] The molecular formula of the positive electrode material in Example 47 is: LiNi 0.8 Co 0.1 Mn 0.08 Mo 0.01 Zr 0.01 O2.

[0450] Example 48

[0451] The difference between the positive electrode material described in Example 48 and the positive electrode material described in Example 1 is that:

[0452] The maximum groove depth of the secondary particles described in Example 48 can be 0.4 μm;

[0453] The doping elements used in the positive electrode material of Example 48 are Mg and Zr;

[0454] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 48 and the spherical diameter D of a single secondary particle satisfy d / D=0.072;

[0455] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0456] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 3.6;

[0457] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 21° and the value of β is 23°.

[0458] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 110°.

[0459] The molecular formula of the positive electrode material in Example 48 is: LiNi 0.8 Co 0.1 Mn 0.08 Mg 0.015 Zr 0.005 O2.

[0460] The properties of the positive electrode materials described in Examples 41 to 48 are shown in Table 5:

[0461] Table 5

[0462]

[0463]

[0464] It can be seen from Table 5 that: from Example 42 and Example 44, it can be seen that as α and β increase, the 300-cycle high-temperature cycle capacity retention rate deteriorates; from Example 41 and Example 44, it can be seen that as d / D increases, the maximum compaction gradually decreases; from Example 44 and Example 48, it can be seen that as the Ni content increases, the 300-cycle high-temperature cycle capacity retention rate deteriorates.

[0465] Example 49

[0466] The difference between the positive electrode material described in Example 49 and the positive electrode material described in Example 1 is that:

[0467] The maximum groove depth of the secondary particles described in Example 49 can be 0.3 μm;

[0468] The precursor of the positive electrode material in Example 49 is Ni 0.8 Co 0.1 Al 0.08 Mg 0.02 (OH)2;

[0469] The molar ratio of the lithium source to the total of the metal Ni, Co, Al and Mg ions in Example 49 is 1.1;

[0470] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 49 and the spherical diameter D of a single secondary particle satisfy d / D=0.045;

[0471] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.03;

[0472] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.5;

[0473] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 20° and the value of β is 21°.

[0474] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 34°.

[0475] Example 50

[0476] The difference between the positive electrode material described in Example 50 and the positive electrode material described in Example 1 is that:

[0477] The maximum groove depth of the secondary particles described in Example 50 can be 0.8 μm;

[0478] The precursor of the positive electrode material used in Example 50 is Ni 0.8 Co 0.1 Mn 0.08 Al 0.02 (OH)2;

[0479] The molar ratio of the lithium source to the total of the metal Ni, Co, Al and Mn ions in Example 50 is 1.1;

[0480] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 50 and the spherical diameter D of a single secondary particle satisfy d / D=0.04;

[0481] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.01;

[0482] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 4;

[0483] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 16° and the value of β is 14°.

[0484] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 47°.

[0485] Example 51

[0486] The difference between the positive electrode material described in Example 51 and the positive electrode material described in Example 1 is that:

[0487] The maximum groove depth of the secondary particles described in Example 51 can be 0.3 μm;

[0488] The precursor of the positive electrode material used in Example 51 is Ni 0.5 Co 0.25 Mn 0.23 Al 0.01 Mo 0.01 (OH)2;

[0489] The molar ratio of the lithium source to the sum of the metal Ni, Co, Mn, Al, and Mo ions in Example 51 is 1.1;

[0490] The maximum groove depth d of a single secondary particle of the positive electrode material described in Example 51 and the spherical diameter D of a single secondary particle satisfy d / D=0.01;

[0491] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.005;

[0492] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0493] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 21° and the value of β is 17°.

[0494] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 37°.

[0495] The properties of the positive electrode materials described in Examples 49 to 51 are shown in Table 6:

[0496] Table 6

[0497]

[0498] It can be seen from Table 6 that when the lithium content increases, the 7D gas production and 300-cycle DCR of the positive electrode material are reduced, and it can be seen from Examples 50 and 51 that the smaller the m / D, the lower the 7D production and 300-cycle DCR.

[0499] Example 52

[0500] The difference between the positive electrode material described in Example 52 and the positive electrode material described in Example 1 is that:

[0501] The maximum groove depth of the secondary particles described in Example 52 can be 0.6 μm;

[0502] The maximum groove depth d of a single secondary particle of the positive electrode material described in Example 52 and the spherical diameter D of a single secondary particle satisfy d / D=0.09;

[0503] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.03;

[0504] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 3;

[0505] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 12° and the value of β is 15°.

[0506] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 37°.

[0507] Example 53

[0508] The difference between the positive electrode material described in Example 53 and the positive electrode material described in Example 1 is that:

[0509] The maximum groove depth of the secondary particles described in Example 53 may be 0.5 μm;

[0510] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 53 and the spherical diameter D of a single secondary particle satisfy d / D=0.08;

[0511] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D = 0.01;

[0512] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 8;

[0513] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 22° and the value of β is 21°.

[0514] The angle of the arc of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 45°.

[0515] Example 54

[0516] The difference between the positive electrode material described in Example 54 and the positive electrode material described in Example 1 is that:

[0517] The maximum groove depth of the secondary particles described in Example 54 can be 0.6 μm;

[0518] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 54 and the spherical diameter D of a single secondary particle satisfy d / D=0.08;

[0519] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0520] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 4;

[0521] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 35° and the value of β is 29°.

[0522] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 55°.

[0523] Example 55

[0524] The difference between the positive electrode material described in Example 55 and the positive electrode material described in Example 1 is that:

[0525] The maximum groove depth of the secondary particles described in Example 55 can be 0.7 μm;

[0526] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 55 and the spherical diameter D of a single secondary particle satisfy d / D=0.07;

[0527] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.02;

[0528] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 3.5;

[0529] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 31° and the value of β is 33°.

[0530] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 49°.

[0531] Example 56

[0532] The difference between the positive electrode material described in Example 56 and the positive electrode material described in Example 1 is that:

[0533] The maximum groove depth of the secondary particles described in Example 56 can be 0.4 μm;

[0534] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 56 and the spherical diameter D of a single secondary particle satisfy d / D=0.08;

[0535] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.06;

[0536] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m, which is 1.3;

[0537] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 22° and the value of β is 25°.

[0538] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 66°.

[0539] Example 57

[0540] The difference between the positive electrode material described in Example 57 and the positive electrode material described in Example 1 is that:

[0541] The maximum groove depth of the secondary particles described in Example 57 can be 0.8 μm;

[0542] The maximum groove depth d of a single secondary particle of the positive electrode material of Example 57 and the spherical diameter D of a single secondary particle satisfy d / D=0.06;

[0543] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.03;

[0544] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0545] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 27° and the value of β is 31°.

[0546] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 135°.

[0547] Example 58

[0548] The difference between the positive electrode material described in Example 58 and the positive electrode material described in Example 1 is that:

[0549] The maximum groove depth of the secondary particles described in Example 58 can be 0.6 μm;

[0550] The maximum groove depth d of a single secondary particle of the positive electrode material described in Example 58 and the spherical diameter D of a single secondary particle satisfy d / D=0.06;

[0551] The average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy m / D of 0.03;

[0552] The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is d / m = 2;

[0553] The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively. The value of α is 15° and the value of β is 18°.

[0554] The arc angle of the largest primary particle surrounding the surface of a single secondary particle is γ, and the γ value is: 13°.

[0555] The properties of the positive electrode materials described in Examples 52 to 58 are shown in Table 7:

[0556] Table 7

[0557]

[0558] As can be seen from Table 7: In Example 52, d / D is too large, resulting in a decrease in capacity retention and a decrease in maximum compaction (this conclusion is drawn by comparison with Example 19);

[0559] In Example 53, too large a d / m value will result in a decrease in the capacity retention rate (this conclusion is reached by comparing with Example 20);

[0560] In Examples 54 and 55, α and β are too large, which will cause the DCR to become larger (this conclusion is drawn by comparing with Example 26);

[0561] In Example 56, m / D is too large, which results in high gas production (this conclusion is drawn by comparison with Example 25);

[0562] In Example 57, γ is too large, which will cause both DCR and cycle capacity retention to deteriorate (this conclusion is reached by comparing with Example 10);

[0563] In Example 58, γ is too small, which results in a poor cycle capacity retention rate (this conclusion is reached by comparison with Example 10). The above is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and supplements without departing from the method of the present invention, and such improvements and supplements should also be considered within the scope of protection of the present invention.

Claims

1. A positive electrode material, characterized in that The positive electrode material includes a plurality of secondary particles, wherein the secondary particles are composed of primary particles, the maximum groove depth of a single secondary particle constituting the positive electrode material is d, the spherical diameter of a single secondary particle constituting the positive electrode material is D, the average groove depth of the single secondary particles constituting the positive electrode material is m, the maximum groove depth d of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.005≤d / D≤0.03; the average groove depth m of a single secondary particle and the spherical diameter D of a single secondary particle satisfy 0.001≤m / D≤0.005; The angles occupied by the two primary particles that enclose the maximum groove depth of a single secondary particle in the secondary particle are α and β, respectively, and the value of α is: 0<α≤10°, and the value of β is 0<β≤13°; α is the angle between two tangent lines drawn from the center of the secondary particle to one of the primary particles that forms the maximum groove depth of the secondary particle; β is the angle between two tangent lines drawn from the center of the secondary particle to another primary particle that forms the maximum groove depth of the secondary particle.

2. The positive electrode material according to claim 1, characterized in that The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is 1≤d / m≤5.

3. The positive electrode material according to claim 1, characterized in that The relationship between the maximum groove depth d of a single secondary particle and the average groove depth m of a single secondary particle is 1.5≤d / m≤3.

4. The positive electrode material according to claim 1, characterized in that The maximum groove depth of the secondary particles is 0.2-1.2 μm.

5. The positive electrode material according to claim 1, characterized in that The maximum groove depth of the secondary particles is 0.3-0.8 um.

6. The positive electrode material according to claim 1, characterized in that The cross section of the primary particles surrounding the surface of a single secondary particle is arc-shaped, and the arc angle of the largest primary particle surrounding the surface of the single secondary particle is γ, and the value of γ is: 20°≤γ≤130°; γ is the fullness of the primary particles.

7. The positive electrode material according to claim 1, characterized in that The γ value is: 30°≤γ≤110°.

8. The positive electrode material according to claim 7, characterized in that The γ value is: 45°≤γ≤90°.

9. The positive electrode material according to claim 1, characterized in that The general formula of the positive electrode material is: Li 1+a [Ni x Co y M z M1 b ]O2, of which 0.5 <x<1,0<y<0.3,0<z<0.3,0<a<0.2,0<b<0.2; Wherein, M is one or two of Mn and / or Al; M1 is one or more of Zr, Mg, Ti, Te, Al, Ca, Sr, Sb, Nb, Pb, V, Ge, Se, W, Mo, Zn, and Ce.

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