Positive electrode active material, positive electrode sheet, secondary battery, and electric device

Abstract

The application provides a positive electrode active material, which comprises agglomerate material, the chemical formula of the agglomerate material is Li a Ni x Co y M 1‑x‑y O 2‑b , wherein 0.6≤a≤1.2, 0.6≤x≤1, 0≤y≤0.4, -0.1≤b≤0.1, M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Mo; the primary particle size of the agglomerate material is 100-600 nm; the particle size distribution of the agglomerate material satisfies (Dv90-Dv10) / Dv50≥1.6; and the positive electrode active material can improve the compaction density of the electrode sheet, improve the energy density of the battery, and meet the demand of high-energy-density batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary batteries, in particular to a positive electrode active material, a positive electrode sheet, a secondary battery and an electric device. BACKGROUND

[0002] Since the secondary battery was commercialized, it has rapidly become an energy storage device used in various fields of life and has attracted extensive interest of experts and researchers due to its advantages such as high energy density, high battery voltage, long cycle life and no memory effect. With the development of electronic and electrical equipment, especially the rapid development of electric vehicles, the existing secondary batteries cannot meet the use requirements in terms of energy density and rate performance, so it is urgent to find and prepare materials with high energy density. SUMMARY

[0003] The present application is carried out in view of the above-mentioned problems, and aims to provide a positive electrode active material. The present application improves the compaction density of the electrode sheet by controlling the particle size distribution and primary particle size of the material, improves the energy density of the battery, and the battery has excellent rate performance, meeting the use requirements of new batteries.

[0004] The first aspect of the present application provides a positive electrode active material, which comprises an agglomerate material, the chemical formula of the agglomerate material is Li a Ni x Co y M 1-x-y O 2-b , wherein 0.6≤a≤1.2, 0.6≤x≤1, 0≤y≤0.4, -0.1≤b≤0.1, M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Mo; the primary particle size of the agglomerate material is 100-600 nm, and the particle size distribution of the agglomerate material satisfies (Dv90-Dv10) / Dv50≥1.6.

[0005] The agglomerate material has a large particle size distribution, and the large and small particles in the agglomerate material cooperate to fill the gaps, so that the particles in the positive electrode active material are more densely packed, the compaction density of the electrode sheet is improved, the energy density of the lithium ion battery is improved, and the size of the primary particles of the agglomerate material is controlled within a suitable range, the migration distance of lithium ions is shortened, a large number of active sites of lithium ions are exposed, the specific capacity of the agglomerate material is improved, the battery has excellent rate performance, and the energy density of the material is improved.

[0006] In any embodiment, the chemical formula of the agglomerate material is Li a Ni x Co y M 1-x-yIn O2, 0.6≤a≤1.2, 0.8≤x≤1, 0≤y≤0.2, -0.1≤b≤0.1, optionally, 0.8≤a≤1.2, 0.93≤x≤0.98, 0≤y≤0.07, -0.1≤b≤0.1.

[0007] The positive electrode active material has high gravimetric capacity and good structural stability, and can make the battery have high energy density and excellent rate performance.

[0008] In any embodiment, the primary particle size of the agglomerate material is 200-500 nm.

[0009] The primary particle size of the agglomerate material is within a suitable range, which exposes more lithium ion reaction active sites, improves the gravimetric capacity of the agglomerate material, and improves the energy density of the battery. The primary particle size within the suitable range can also reduce the side reaction between the electrolyte and the material and reduce the loss of irreversible capacity.

[0010] In any embodiment, the particle size Dv50 of the agglomerate material is 6-15 μm, and optionally 7-13 μm.

[0011] The particle size Dv50 of the agglomerate material is within a suitable range, which is beneficial to make the positive electrode sheet have high compaction density and improve the energy density of the battery. At the same time, the agglomerate material has a suitable Dv50, which can improve the ion conductivity and electronic conductivity of the material, and the battery has excellent rate performance.

[0012] In any embodiment, the particle size distribution of the agglomerate material is monomodal, and the monomodal peak is located at 6-15 μm, and optionally 7-13 μm.

[0013] The particle size distribution of the agglomerate material is monomodal, and the monomodal peak is within a suitable range, which is beneficial to make the positive electrode sheet have high compaction density and improve the energy density of the battery. At the same time, the monomodal peak within the suitable range indicates that the material has a suitable particle size, which can improve the ion conductivity and electronic conductivity of the material and improve the rate performance of the battery.

[0014] In any embodiment, the particle size distribution of the agglomerate material satisfies 1.6≤(Dv90-Dv10) / Dv50≤2.3, and optionally, the particle size distribution of the agglomerate material satisfies 1.8≤(Dv90-Dv10) / Dv50≤2.1.

[0015] The particle size distribution of the agglomerate material is within a suitable range, which on the one hand can improve the compaction density of the sheet and the energy density of the battery through the size particle grading, and on the other hand, the suitable particle size distribution can reduce the influence of too large or too small particles in the material on the compaction density.

[0016] In any embodiment, the specific surface area of the agglomerate material is 0.5m 2 / g-0.9m 2 / g.

[0017] The specific surface area of the agglomerate material is within a suitable range, shortens the lithium ion migration distance, improves the rate performance of the battery, in addition, a suitable specific surface area can also expose more lithium ion reaction active sites, increase the gram capacity of the pole piece, and improve the energy density of the battery, while a suitable range of specific surface area can also reduce the side reaction between the electrolyte and the material, and reduce the loss of irreversible capacity.

[0018] In any embodiment, the agglomerate material includes first agglomerates and second agglomerates, the particle size Dv50 of the first agglomerates is 9-15pm, and the particle size Dv50 of the second agglomerates is 4-8pm.

[0019] The particle size Dv50 of the first agglomerates and the second agglomerates is within a suitable range, so that the agglomerate material has a suitable particle size distribution, the large and small gaps between the particles can be effectively filled, the agglomerate material is tightly packed, the compaction density of the pole piece is improved, and the energy density of the battery is improved.

[0020] In any embodiment, the chemical formula of the first agglomerate is Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 , and the chemical formula of the second agglomerate is Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2 , x1≥x2,

[0021] Wherein 0.6≤a1≤1.2, 0.6≤x1≤1, 0≤y1≤0.4, -0.1≤b1≤0.1, 0.6≤a2≤1.2, 0.4≤x2≤1, 0≤y2≤0.6, -0.1≤b2≤0.1, M1, M2 each independently includes one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Mo.

[0022] The first agglomerate has a large Dv50, the first agglomerate has relatively few lithium ion reaction active sites, and by increasing the nickel content, the purpose of high gram capacity can be achieved, and the energy density of the battery is improved. The second agglomerate has a small particle size Dv50, the second agglomerate has relatively many lithium ion reaction active sites, and in the case of relatively low nickel content, the purpose of high gram capacity can be achieved. Through the cooperation of the particle size Dv50 and the nickel content of the first agglomerate and the second agglomerate, the energy density of the battery is improved.

[0023] In any embodiment, the first agglomerate has a chemical formula of Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 wherein 0.8≤a1≤1.2, 0.94≤x1≤0.98, 0≤y1≤0.06, -0.1≤b1≤0.1.

[0024] In any embodiment, the second agglomerate has a chemical formula of Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2 wherein 0.8≤a2≤1.2, 0.93≤x2≤0.96, 0≤y2≤0.07, -0.1≤b2≤0.1.

[0025] In any embodiment, the primary particle size of the first agglomerate is greater than the primary particle size of the second agglomerate.

[0026] With the premise that the particle size Dv50 of the first agglomerate is greater than the particle size Dv50 of the second agglomerate, controlling the primary particle size of the first agglomerate to be greater than the primary particle size of the second agglomerate can improve the compaction density of the first agglomerate, while the primary particle size of the second agglomerate is relatively small, shortening the transmission distance of lithium ions, improving the ion conductivity and electronic conductivity of the second agglomerate, and exposing more active sites for lithium ion reaction, thereby comprehensively improving the energy density and rate performance of the battery.

[0027] In any embodiment, the primary particle size of the first agglomerate is 100-1000 nm, and the primary particle size of the second agglomerate is 100-300 nm.

[0028] The appropriate primary particle size range of the first agglomerate can improve the compaction density of the pole piece and improve the energy density of the battery, while the appropriate primary particle size range of the second agglomerate is conducive to the development of the specific capacity of the second agglomerate and the improvement of the rate performance of the battery.

[0029] In any embodiment, the particle size distribution of the first agglomerate and the second agglomerate satisfies (Dv90-Dv10) / Dv50≤1.50.

[0030] The particle size distribution of the first agglomerate and the second agglomerate is within an appropriate range, which reduces the influence of the presence of a large number of particles with large particle sizes or small particle sizes in the material on the compaction density.

[0031] In any embodiment, the particle size distribution of the first agglomerate satisfies 0.50≤(Dv90-Dv10) / Dv50≤1.30, and the particle size distribution of the second agglomerate satisfies 1.30≤(Dv90-Dv10) / Dv50≤1.50.

[0032] The particle size distribution of the first agglomerate in a suitable range can provide sufficient filling space, and the particle size distribution of the second agglomerate in a suitable range can sufficiently fill the space between the first agglomerates, and the mutual cooperation of the two can improve the compaction density.

[0033] In any embodiment, the mass ratio of the first agglomerate to the second agglomerate is 1:1-9:1.

[0034] The particle size Dv50 of the first agglomerate is relatively large, and the first agglomerate plays a role of skeleton, and the particle size Dv50 of the second agglomerate is relatively small, and the second agglomerate plays a role of filling the gap between the skeleton. The mass ratio of the first agglomerate to the second agglomerate in a suitable range makes the positive electrode active material have a suitable particle size distribution, which can improve the compaction density of the electrode sheet and improve the energy density of the battery.

[0035] The second aspect of the present application provides a positive electrode sheet, comprising a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises the positive electrode active material of the first aspect.

[0036] The positive electrode sheet has high compaction density, area density and low elongation, which improves the gram capacity of the electrode sheet and improves the use performance and processing performance of the electrode sheet.

[0037] In any embodiment, the mass content of the positive electrode active material is 95%-99.5%, based on the total mass of the positive electrode film layer.

[0038] The mass content of the positive electrode active material in the above range can improve the gram capacity of the electrode sheet and improve the energy density of the battery.

[0039] In any embodiment, when the compaction density of the positive electrode sheet is 3.5g / cm 3 -3.8g / cm 3 , the length direction elongation of the positive electrode sheet is 7%-8%.

[0040] The length direction elongation of the electrode sheet in the above range improves the flexibility of the electrode sheet, reduces the possibility of brittle fracture in the process of winding or hot pressing of the electrode sheet, and improves the use performance of the electrode sheet.

[0041] In any embodiment, the coating area density of the positive electrode film layer is 21.5mg / cm 2 -32.5mg / cm 2 .

[0042] The coating surface density of the positive electrode film layer within the above range can increase the gram capacity of the electrode tab, and increase the energy density of the battery.

[0043] In any embodiment, the positive electrode tab has a compaction density of 3.5 g / cm 3 - 3.8 g / cm 3 .

[0044] The compaction density of the positive electrode tab within the above range can increase the gram capacity of the electrode tab, and increase the energy density of the battery.

[0045] A third aspect of the present application provides a secondary battery comprising the positive electrode tab of the second aspect of the present application.

[0046] In any embodiment, the secondary battery comprises a lithium ion battery.

[0047] A fourth aspect of the present application provides an electric device comprising the secondary battery of the third aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 is a schematic diagram of a secondary battery according to an embodiment of the present application;

[0049] Figure 2 is an exploded view of the secondary battery according to an embodiment of the present application shown in FIG. 1; Figure 1

[0050] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application;

[0051] Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0052] Figure 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4; Figure 4

[0053] is a schematic diagram of an electric device using the secondary battery according to an embodiment of the present application as a power source. Figure 6 BRIEF DESCRIPTION OF REFERENCE NUMERALS

[0054] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 cover plate.

[0055] DETAILED DESCRIPTION

[0056] ​​Hereinafter, specific embodiments of the binder, the production method, the electrode, the battery, and the electric device of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters known to those skilled in the art, repeated description of substantially identical configurations, is omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0057] The ranges disclosed herein are defined by their lower and upper limits. Ranges can be inclusive or exclusive of their endpoints, and all ranges and sub-ranges are combinable. For example, if a range is listed as 60-120 and 80-110, it is understood that 60-110 and 80-120 are also expressly stated. Moreover, if a range is listed as 1-2 and 3-5, it is understood that 1-5, 1-3, 2-5, and 2-3 are also expressly stated. In the present application, unless otherwise indicated, a numerical range "a-b" is intended to indicate any and all sub-ranges between (and including) the minimum value a and the maximum value b in which each and every value from a to b is encompassed. For example, the numerical range "0-5" is intended to indicate the entire range of values from 0 to 5, inclusive of all integer and fractional values therebetween. Additionally, if a parameter is stated to be an integer ≥ 2, it is understood that the parameter is also disclosed to be, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0058] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0059] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0060] If not specified otherwise, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0061] If not specified otherwise, the terms "comprising" and "including" as used in the present application are open-ended and also include the case where the listed steps / compositions are the only steps / compositions. For example, the terms "comprising" and "including" can mean that the method can further comprise other steps / compositions not listed, or can mean that the method only comprises the listed steps / compositions.

[0062] If not specified otherwise, the term "or" as used in the present application is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following are satisfied by 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).

[0063] The compaction density, platform voltage and gravimetric capacity of ternary materials are widely concerned. The positive electrode tab of the ternary material generally uses a compaction density ≤3.3 g / cm 3 When the compaction density > 3.3 g / cm 3 , the high-nickel ternary positive electrode tab uses excessive compaction, which is easy to cause secondary particle structure rupture or cracks, and the exposed fresh interface will react with the electrolyte, accelerate the degradation of the battery, and reduce the service life and safety performance of the battery. When the compaction of the ternary positive electrode tab is too low, the contribution to the improvement of the energy density of the battery is not great, the energy density is reduced, and the battery endurance is reduced. Therefore, it is necessary to develop a positive active material with high compaction density and high energy density to meet the use needs of new batteries.

[0064] [Positive active material]

[0065] Based on this, the present application provides a positive active material, which comprises an agglomerate material, the chemical formula of the agglomerate material is Li a Ni x Co y M 1-x-y O 2-bWhere 0.6≤a≤1, 0.6≤x≤1, 0≤y≤0.4, -0.1≤b≤0.1, and M includes one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, and Mo; the primary particle size of the agglomerate material is 100–600 nm, and the particle size distribution of the agglomerate material satisfies (Dv90-Dv10) / Dv50≥1.6.

[0066] In this paper, the term "aggregate" refers to an aggregate formed by primary particles combining under the influence of interaction forces, and the particles within the aggregate are called primary particles.

[0067] In this article, the term "primary particle" refers to a particle before it agglomerates.

[0068] The primary particle size can be measured using methods known in the art. As an example, after cold pressing, the sample is cut open using an Ar particle beam to expose the end face, and images of the end face are obtained using a scanning electron microscope (SEM). The size of the primary particles in the sample is measured based on the SEM images. At least three samples are measured, with at least 50 data points for each sample, and the average of these data points is taken as the primary particle size of the sample.

[0069] In this paper, the term "Dv90" refers to the particle size that reaches 90% of the total volume in the particle size distribution of powder particles based on volume.

[0070] In this paper, the term "Dv10" refers to the particle size that reaches 10% of the total volume in the particle size distribution of powder particles based on volume.

[0071] In this paper, the term "Dv50" refers to the particle size that accounts for 50% of the total volume of a powder particle in its volumetric particle size distribution.

[0072] The test methods for particle volume distribution sizes Dv10, Dv50, and Dv90 described above can be performed using methods known in the art. For example, particle size distribution can be determined using a Malvern 3000 instrument, in accordance with GB / T 19077-2016 / ISO 13320:2009, laser diffraction method.

[0073] In some implementations, M includes Mn or Al.

[0074] Mn or Al can provide support and stability during charging and discharging, which helps improve safety performance.

[0075] In some implementations, M includes Sb or Nb.

[0076] Sb or Nb can refine the grain size, making the primary particle size of the material smaller, thereby further improving the material's specific capacity and rate performance.

[0077] In some implementations, M includes Sr.

[0078] Sr is a flux. Under the premise of obtaining a suitable particle size, the flux can reduce the sintering temperature and reduce the formation of rock salt phase, thereby improving the capacity and cycle life of the material and improving the cycle life of the battery.

[0079] The chemical formula of agglomerate materials can be determined using methods known in the art. As an example, the chemical formula of the agglomerate material can be determined by measuring the proportion of each element in the material using inductively coupled plasma spectrometry (ICP) (e.g., Spectroblue type).

[0080] In some embodiments, the primary particle size of the agglomerate material can be any value or a range of any two of 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, and 600 nm.

[0081] In some embodiments, the particle size distribution of the agglomerate material satisfies any one of the following: (Dv90-Dv10) / Dv50≥1.6, (Dv90-Dv10) / Dv50≥1.7, (Dv90-Dv10) / Dv50≥1.8, (Dv90-Dv10) / Dv50≥1.9, (Dv90-Dv10) / Dv50≥2, (Dv90-Dv10) / Dv50≥2.1, (Dv90-Dv10) / Dv50≥2.2, (Dv90-Dv10) / Dv50≥2.3, (Dv90-Dv10) / Dv50≥2.4.

[0082] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In this context, 'a' is any value from 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, or a range consisting of any two of these values.

[0083] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In the expression, x is any value from 0.6, 0.7, 0.8, 0.85, 0.9, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, or a range consisting of any two of these values.

[0084] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In the given equation, y is any value from 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.1, 0.15, 0.2, 0.3, 0.4, or a range consisting of any two of these values.

[0085] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In this context, b is any value among -0.1, 0, and 0.1, or a range consisting of any two of these values.

[0086] By controlling the particle size distribution of the agglomerate material, the particles of varying sizes cooperate to fill the gaps, improving the interparticle void space and volume utilization. This results in a denser particle packing in the positive electrode active material, enhancing the electrode's compressive strength and compaction density, thereby increasing the energy density of the lithium-ion battery. Simultaneously, by controlling the primary particle size of the agglomerate material within a suitable range, the migration distance of lithium ions is shortened, and a large number of lithium-ion active sites are exposed, increasing the specific capacity of the material. This leads to excellent rate performance and improved energy density. Furthermore, the close packing of the agglomerate material prevents particle displacement under high pressure, resulting in a lower elongation and improved flexibility of the electrode.

[0087] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In the given condition, 0.6≤a≤1.2, 0.8≤x≤1, 0≤y≤0.2, and -0.1≤b≤0.1.

[0088] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In this context, 'a' is any value from 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, or a range consisting of any two of these values.

[0089] In some implementations, the chemical formula Li a Ni x Co y M1-x-y O 2-b In the expression, x is any value from 0.8, 0.85, 0.9, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, or a range consisting of any two of these values.

[0090] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In the expression, y is any value from 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.1, 0.15, 0.2, or a range consisting of any two of these values.

[0091] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In this context, b is any value among -0.1, 0, and 0.1, or a range consisting of any two of these values.

[0092] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In the given condition, 0.8≤a≤1.2, 0.93≤x≤0.98, 0≤y≤0.07, and -0.1≤b≤0.1.

[0093] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In this context, 'a' is any value from 0.8, 0.9, 1.0, 1.1, 1.2, or a range consisting of any two of these values.

[0094] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In the expression, x is any value from 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, or a range consisting of any two of these values.

[0095] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-bIn the given information, y is any value from 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, or a range consisting of any two of these values.

[0096] In some implementations, the chemical formula Li a Ni x Co y M 1-x-y O 2-b In this context, b is any value among -0.1, 0, and 0.1, or a range consisting of any two of these values.

[0097] Within the aforementioned chemical formula range, aggregates exhibit high specific capacity, resulting in batteries with high energy density.

[0098] In some embodiments, the primary particle size of the agglomerate material is 200-500 nm.

[0099] In some embodiments, the primary particle size of the agglomerate material is any value of 200 nm, 300 nm, 400 nm, 500 nm, or a range consisting of any two of these values.

[0100] When the primary particle size of agglomerated materials is within a suitable range, more lithium-ion reactive sites are exposed, which increases the specific capacity of the agglomerated materials, improves the energy density of the battery, and reduces side reactions between the electrolyte and the materials, thus reducing irreversible capacity loss.

[0101] In some embodiments, the particle size Dv50 of the agglomerate material is 6-15 μm. In some embodiments, the particle size Dv50 of the agglomerate material is any value or a range of any two values ​​from 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, and 15 μm.

[0102] When the particle size Dv50 of agglomerate materials is within a suitable range, it is beneficial to enable the positive electrode sheet to have a high compaction density, thereby improving the energy density of the battery. At the same time, an appropriate Dv50 of agglomerate materials can improve the ion conductivity and electronic conductivity of the material, thereby improving the rate performance of the battery.

[0103] In some embodiments, the particle size Dv50 of the agglomerate material is 7-13 μm. In some embodiments, the particle size Dv50 of the agglomerate material is any value or a range of any two of the following: 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm.

[0104] When the particle size Dv50 of the agglomerate material is within a suitable range, it is beneficial to enable the positive electrode sheet to have a high compaction density and improve the energy density of the battery.

[0105] In some embodiments, the particle size distribution of the aggregated material, as determined by particle size analysis laser diffraction, is unimodal, with the peak position located at 6-15 μm.

[0106] In this paper, particle size distribution was determined by laser diffraction method according to GB / T 19077-2016 / ISO 13320:2009, using Malvern 3000 equipment. The particle size distribution map based on volume distribution was obtained, and the peak position of the single peak was determined from the particle size distribution map.

[0107] In some implementations, the peak position of a single peak is located at any value or a range of any two values ​​among 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, and 15μm.

[0108] The particle size distribution of agglomerated materials is unimodal, and the peak position is within a suitable range, which is beneficial to enable the positive electrode sheet to have a high compaction density and improve the energy density of the battery. At the same time, the unimodal peak position within a suitable range indicates that the material has a suitable particle size, which can improve the material's ion conductivity and electronic conductivity, and improve the rate performance of the battery.

[0109] In some embodiments, the peak position of a single peak is located between 7 and 13 μm. In some embodiments, the peak position of a single peak is located within any value of 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, or 13 μm, or within a range of any two of these values.

[0110] A single peak position within a suitable range is beneficial for the positive electrode sheet to have a high compaction density, thereby increasing the energy density of the battery.

[0111] In some embodiments, the particle size distribution of the agglomerate material satisfies 1.6 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.3. In some embodiments, the particle size distribution of the agglomerate material satisfies 1.6 ≤ (Dv90 - Dv10) / Dv50 ≤ 1.7, 1.6 ≤ (Dv90 - Dv10) / Dv50 ≤ 1.8, 1.6 ≤ (Dv90 - Dv10) / Dv50 ≤ 1.9, 1.6 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.0, 1.6 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.1, 1.6 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.2, 1.6 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.3. Dv10) / Dv50≤2.3, 1.7≤(Dv90-Dv10) / Dv50≤1.8, 1.7≤(Dv90-Dv10) / Dv50≤1.9, 1.7≤(Dv90-Dv10) / Dv50≤2.0, 1 .7≤(Dv90-Dv10) / Dv50≤2.1, 1.7≤(Dv90-Dv10) / Dv50≤2.2, 1.7≤(Dv90-Dv10) / Dv50≤2.3, 1.8≤(Dv90-Dv10) / D v50≤1.9, 1.8≤(Dv90-Dv10) / Dv50≤2.0, 1.8≤(Dv90-Dv10) / Dv50≤2.1, 1.8≤(Dv90-Dv10) / Dv50≤2.2, 1.8≤(Dv9 0-Dv10) / Dv50≤2.3, 1.9≤(Dv90-Dv10) / Dv50≤2.0, 1.9≤(Dv90-Dv10) / Dv50≤2.1, 1.9≤(Dv90-Dv10) / Dv50≤2.2 Any one of the following: 1.9≤(Dv90-Dv10) / Dv50≤2.3, 2.0≤(Dv90-Dv10) / Dv50≤2.1, 2.0≤(Dv90-Dv10) / Dv50≤2.2, 2.0≤(Dv90-Dv10) / Dv50≤2.3, 2.1≤(Dv90-Dv10) / Dv50≤2.2, 2.1≤(Dv90-Dv10) / Dv50≤2.3, 2.2≤(Dv90-Dv10) / Dv50≤2.3.

[0112] When the particle size distribution of agglomerated materials is within a suitable range, on the one hand, the compaction density of the electrode can be improved through particle size gradation, thereby increasing the energy density of the battery. On the other hand, a suitable particle size distribution reduces the impact of excessively large or small particles on the compaction density and also avoids the pulverization of excessively small particles during cycling, which would lead to cell deterioration. In addition, excessively large or small particles can also affect the preparation of the positive electrode slurry, making the slurry prone to gelation and affecting its processing performance.

[0113] In some embodiments, the particle size distribution of the agglomerate material satisfies 1.8 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.1. In some embodiments, the particle size distribution of the agglomerate material satisfies any one of the following: 1.8 ≤ (Dv90 - Dv10) / Dv50 ≤ 1.9, 1.8 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.0, 1.8 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.1, 1.9 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.0, 1.9 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.1, and 2.0 ≤ (Dv90 - Dv10) / Dv50 ≤ 2.1.

[0114] When the particle size distribution of the agglomerates is within a suitable range, the positive electrode sheet has a suitable compaction density, thereby improving the energy density of the battery.

[0115] In some embodiments, the specific surface area of ​​the agglomerate material is 0.5 m². 2 / g-0.9m 2 / g. In some embodiments, the specific surface area of ​​the agglomerate material can be 0.5m². 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 Any value in / g or a range consisting of any two of its values.

[0116] Specific surface area can be measured using any method known in the art. For example, GB / T 19587-2017, "Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method," can be referenced, and the measurement can be performed using the TriStar II 3020 equipment.

[0117] When the specific surface area of ​​agglomerated materials is within a suitable range, the lithium-ion migration distance is shortened, improving the rate performance of the battery. In addition, a suitable specific surface area can also expose more lithium-ion reactive sites, increasing the specific capacity of the electrode and the energy density of the battery. At the same time, a suitable specific surface area can also reduce side reactions between the electrolyte and the material, reducing irreversible capacity loss.

[0118] In some embodiments, the agglomerate material includes a first agglomerate and a second agglomerate, wherein the particle size Dv50 of the first agglomerate is 9-15 μm and the particle size Dv50 of the second agglomerate is 4-8 μm.

[0119] In some embodiments, the particle size Dv50 of the first agglomerate is any value of 9 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or a range of any two of these values.

[0120] In some embodiments, the particle size Dv50 of the second agglomerate is any value of 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or a range of any two of these values.

[0121] The particle size Dv50 of the first and second aggregates refers to the test method for the particle size Dv50 of the agglomerate material.

[0122] The first agglomerate with a relatively large particle size Dv50 can serve as the skeleton of the electrode. A suitable particle size Dv50 can prevent cracks from appearing at the edges of large particles and improve the battery's lifespan. The second agglomerate with a relatively small particle size Dv50 can serve as a filler for the skeleton of the first agglomerate, improving space utilization.

[0123] The particle size Dv50 of the first and second aggregates is within a suitable range, which makes the aggregate material have a suitable particle size distribution, and the gaps between the particles can be effectively filled. The aggregate material is tightly packed, which increases the compaction density of the electrode and the energy density of the battery.

[0124] In some embodiments, the chemical formula of the first aggregate is Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 The chemical formula of the second aggregate is Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2 x1≥x2,

[0125] Where 0.6≤a1≤1.2, 0.6≤x1≤1, 0≤y1≤0.4, -0.1≤b1≤0.1, 0.6≤a2≤1.2, 0.4≤x2≤1, 0≤y2≤0.6, -0.1≤b2≤0.1, and M1 and M2 each independently include one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, and Mo.

[0126] In some implementations, M1 or M2 each independently contains Mn or Al.

[0127] In some implementations, the chemical formula Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 In this context, a1 is any value from 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, or a range consisting of any two of these values.

[0128] In some implementations, the chemical formula Lia1 Ni x1 Co y M1 1-x1-y1 O 2-b1 In the given information, x1 is any value from 0.6, 0.7, 0.8, 0.85, 0.9, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, or a range consisting of any two of these values.

[0129] In some implementations, the chemical formula Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 In the given information, y1 is any value from 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.1, 0.15, 0.2, 0.3, 0.4, or a range consisting of any two of these values.

[0130] In some implementations, the chemical formula Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 In this context, b1 is any value among -0.1, 0, and 0.1, or a range consisting of any two of these values.

[0131] In some implementations, the chemical formula Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2 In this context, a2 is any value from 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, or a range consisting of any two of these values.

[0132] In some implementations, the chemical formula Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2 In the given information, x2 is any value from 0.4, 0.5, 0.6, 0.7, 0.8, 0.85, 0.9, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, or a range consisting of any two of these values.

[0133] In some implementations, the chemical formula Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2In the given information, y2 represents any value from 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, and 0.6, or a range consisting of any two of these values.

[0134] In some implementations, the chemical formula Li a2 Ni x2 Co y2 M1 1-x2-y2 O 2-b2 In the middle, b2 is

[0135] Any value from -0.1, 0, 0.1, or a range consisting of any two of these values.

[0136] The chemical formulas of the first and second aggregates are confirmed by referring to the test methods for confirming the chemical formulas of aggregate materials.

[0137] The first aggregate has a large particle size (Dv50) and relatively few lithium-ion reactive sites. By increasing the nickel content, a high specific capacity can be achieved, thus improving the battery's energy density. The second aggregate has a small particle size (Dv50) and relatively many lithium-ion reactive sites. Even with a relatively low nickel content, a high specific capacity can be achieved. Through the synergistic effect of the particle size (Dv50) of the first and second aggregates and the nickel content, the battery's energy density is improved.

[0138] In some embodiments, the first aggregate has the chemical formula Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 In the given condition, 0.8≤a1≤1.2, 0.94≤x1≤0.98, 0≤y1≤0.06, and -0.1≤b1≤0.1.

[0139] In some implementations, a1 is any value from 0.8, 0.9, 1.0, 1.1, 1.2 or a range of any two values ​​therein.

[0140] In some implementations, x1 is any value from 0.94, 0.95, 0.96, 0.97, 0.98 or a range of any two values ​​therein.

[0141] In some implementations, y1 is any value from 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, or a range of any two values ​​therein.

[0142] In some implementations, b1 is any value among -0.1, 0, 0.1, or a range consisting of any two of these values.

[0143] In some embodiments, the chemical formula of the second aggregate is Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2 In the given equation, 0.8≤a²≤1.2, 0.93≤x²≤0.96, 0≤y²≤0.07, and -0.1≤b²≤0.1.

[0144] In some implementations, a2 is any value from 0.8, 0.9, 1.0, 1.1, 1.2 or a range of any two values ​​therein.

[0145] In some implementations, x2 is any value from 0.93, 0.94, 0.95, 0.96 or a range of any two of these values.

[0146] In some implementations, y2 is any value from 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, or a range of any two values ​​therein.

[0147] In some implementations, b2 is any value among -0.1, 0, 0.1, or a range of any two of these values.

[0148] The chemical formulas of the first aggregate and the second aggregate are within the above range. The first aggregate and the second aggregate have high specific capacity, and the battery has high energy density.

[0149] In some implementations, the primary particle size of the first agglomerate is larger than that of the primary particle size of the second agglomerate.

[0150] With the particle size Dv50 of the first agglomerate being larger than that of the second agglomerate, controlling the primary particle size of the first agglomerate to be larger than that of the second agglomerate can increase the compaction density of the first agglomerate. At the same time, the primary particle size of the second agglomerate is relatively small, which shortens the lithium-ion transport distance, improves the ion conduction and electronic conduction properties of the second agglomerate, and exposes more active sites for lithium-ion reactions, thereby comprehensively improving the energy density and rate performance of the battery.

[0151] In some embodiments, the primary particle size of the first agglomerate is 100-1000 nm, and the primary particle size of the second agglomerate is 100-300 nm.

[0152] In some embodiments, the primary particle size of the first agglomerate is any value or a range of any two values ​​from 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, and 1000nm.

[0153] In some embodiments, the primary particle size of the second agglomerate is any value of 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, or a range consisting of any two of these values.

[0154] The primary particle size of the first and second aggregates was tested using the same method as for agglomerate materials.

[0155] A suitable primary particle size range for the first agglomerate can improve the compaction density of the electrode and increase the energy density of the battery. At the same time, a suitable primary particle size range for the second agglomerate is beneficial to the utilization of the specific capacity of the second agglomerate and to improving the rate performance of the battery.

[0156] In some embodiments, the particle size distribution of the first aggregate and the second aggregate satisfies (Dv90-Dv10) / Dv50≤1.50.

[0157] In some embodiments, the particle size distribution of the first agglomerate satisfies (Dv90-Dv10) / Dv50≤0.4, (Dv90-Dv10) / Dv50≤0.5, (Dv90-Dv10) / Dv50≤0.6, (Dv90-Dv10) / Dv50≤0.7, (Dv90-Dv10) / Dv50≤0.8, and (Dv90-Dv10) / Dv50≤0.5. Any one of the following: 0≤0.9, (Dv90-Dv10) / Dv50≤1.0, (Dv90-Dv10) / Dv50≤1.1, (Dv90-Dv10) / Dv50≤1.2, (Dv90-Dv10) / Dv50≤1.3, (Dv90-Dv10) / Dv50≤0.4, 0.6≤(Dv90-Dv10) / Dv50≤1.5.

[0158] In some embodiments, the particle size distribution of the second agglomerate satisfies (Dv90-Dv10) / Dv50≤0.4, (Dv90-Dv10) / Dv50≤0.5, (Dv90-Dv10) / Dv50≤0.6, (Dv90-Dv10) / Dv50≤0.7, (Dv90-Dv10) / Dv50≤0.8, and (Dv90-Dv10) / Dv50≤0.5. Any one of the following: 0≤0.9, (Dv90-Dv10) / Dv50≤1.0, (Dv90-Dv10) / Dv50≤1.1, (Dv90-Dv10) / Dv50≤1.2, (Dv90-Dv10) / Dv50≤1.3, (Dv90-Dv10) / Dv50≤0.4, 0.6≤(Dv90-Dv10) / Dv50≤1.5.

[0159] The particle size distribution of the first and second aggregates is referenced in the test method for aggregate materials.

[0160] The particle size distribution of the first and second aggregates is within a suitable range, which reduces the influence of large or small particles on the compaction density of the material, resulting in a battery with high compaction density and high energy density.

[0161] In some embodiments, the particle size distribution of the first agglomerate satisfies 0.50≤(Dv90-Dv10) / Dv50≤1.30, and the particle size distribution of the second agglomerate satisfies 1.30≤(Dv90-Dv10) / Dv50≤1.50.

[0162] In some embodiments, the particle size distribution of the first agglomerate satisfies the following conditions: 0.50≤(Dv90-Dv10) / Dv50≤0.6, 0.50≤(Dv90-Dv10) / Dv50≤0.7, 0.50≤(Dv90-Dv10) / Dv50≤0.8, 0.50≤(Dv90-Dv10) / Dv50≤0.9, 0.50≤(Dv90-Dv10) / Dv50≤1.0, 0.50≤(Dv90-Dv10) / Dv50≤1.1, 0.50≤(Dv90-Dv10) / Dv50≤1.2, 0.50≤(Dv90-Dv10) / Dv50≤1.3, 0.6. ≤(Dv90-Dv10) / Dv50≤0.7, 0.6≤(Dv90-Dv10) / Dv50≤0.8, 0.6≤(Dv90-D v10) / Dv50≤0.9, 0.6≤(Dv90-Dv10) / Dv50≤1.0, 0.6≤(Dv90-Dv10) / Dv5 0≤1.1, 0.6≤(Dv90-Dv10) / Dv50≤1.2, 0.6≤(Dv90-Dv10) / Dv50≤1.3, 0. 7≤(Dv90-Dv10) / Dv50≤0.8, 0.7≤(Dv90-Dv10) / Dv50≤0.9, 0.7≤(Dv90- Dv10) / Dv50≤1.0, 0.7≤(Dv90-Dv10) / Dv50≤1.1, 0.7≤(Dv90-Dv10) / Dv50≤1.2, 0.7≤(Dv90-Dv10) / Dv50≤1.3, 0.8≤(Dv90-Dv10) / Dv50≤0.9, 0 .8≤(Dv90-Dv10) / Dv50≤1.0, 0.8≤(Dv90-Dv10) / Dv50≤1.1, 0.8≤(Dv90 -Dv10) / Dv50≤1.2, 0.8≤(Dv90-Dv10) / Dv50≤1.3, 0.9≤(Dv90-Dv10) / D Any one of the following: v50≤1.0, 0.9≤(Dv90-Dv10) / Dv50≤1.1, 0.9≤(Dv90-Dv10) / Dv50≤1.2, 0.9≤(Dv90-Dv10) / Dv50≤1.3, 1≤(Dv90-Dv10) / Dv50≤1.1, 1≤(Dv90-Dv10) / Dv50≤1.2, 1≤(Dv90-Dv10) / Dv50≤1.3, 1.1≤(Dv90-Dv10) / Dv50≤1.2, 1.1≤(Dv90-Dv10) / Dv50≤1.3, 1.2≤(Dv90-Dv10) / Dv50≤1.3.

[0163] In some implementations, the particle size distribution of the second agglomerate satisfies 1.30≤(Dv90-Dv10) / Dv50≤1.50.

[0164] In some embodiments, the particle size distribution of the second agglomerate satisfies any one of 1.30≤(Dv90-Dv10) / Dv50≤1.40, 1.30≤(Dv90-Dv10) / Dv50≤1.5, or 1.40≤(Dv90-Dv10) / Dv50≤1.50.

[0165] The first agglomerate has a particle size distribution within a suitable range, which can provide sufficient filling space. The second agglomerate has a particle size distribution within a suitable range, which can fully fill the space between the first agglomerates. The cooperation between the two improves the compaction density and the energy density of the battery.

[0166] In some embodiments, the mass ratio of the first aggregate to the second aggregate is 1:1 to 9:1.

[0167] In some embodiments, the mass ratio of the first aggregate to the second aggregate is any value from 1:1, 2:1, 3:1, 4:1, 5:1, 5:1, 7:1, 8:1, 9:1, or a range of any two of these values.

[0168] The first agglomerate has a relatively large particle size (Dv50) and acts as a framework, while the second agglomerate has a relatively small particle size (Dv50) and fills the gaps in the framework. A suitable mass ratio of the first to second agglomerates ensures an appropriate particle size distribution in the positive electrode active material, which can improve the compaction density of the electrode and thus the energy density of the battery. Simultaneously, the smaller second agglomerates have relatively low mechanical strength and are more easily broken under the pressure of the rollers. A suitable mass ratio of the first to second agglomerates can improve the structural stability of the material and enhance the safety performance of the battery.

[0169] In some embodiments, the specific capacity of the positive electrode active material is 230-245 mAh / g.

[0170] The specific capacity of the positive electrode active material can be tested using any method known in the art. As an example, the secondary battery is discharged at a constant current of 0.33C to 2.8V and allowed to stand for 30 minutes; then charged at a constant current of 0.33C to 4.25V and then charged at a constant voltage of 0.05C until the voltage stabilizes, and allowed to stand for 30 minutes; finally, it is discharged at a constant current of 0.33C to 2.8V, at which point the discharge capacity is read, and the ratio of the initial discharge capacity of the secondary battery to the mass of the positive electrode active material is calculated and recorded as the specific capacity of the positive electrode active material, where 1C = 230mAh.

[0171] [Positive electrode plate]

[0172] The positive electrode includes a positive current collector and a positive electrode film layer formed on at least a portion of the surface of the positive current collector, the positive electrode film layer including the positive electrode active material in some embodiments.

[0173] This positive electrode has high compaction density, areal density and low elongation, which improves the specific capacity of the electrode and enhances its performance in use and processing.

[0174] In some embodiments, the mass content of the positive electrode active material is 95% to 99.5% based on the total mass of the positive electrode film. In some embodiments, the mass content of the positive electrode active material, based on the total mass of the positive electrode film, is any value or a range of any two of 95%, 96%, 97%, 98%, 99%, and 99.5%.

[0175] Within the above-mentioned range, the mass content of positive electrode active material can increase the specific capacity of the electrode and improve the energy density of the battery.

[0176] In some implementations, the compaction density of the positive electrode sheet is 3.5 g / cm³. 3 -3.8g / cm 3 At that time, the elongation of the positive electrode sheet in the longitudinal direction is 7% to 8%. In some embodiments, the elongation of the positive electrode sheet in the longitudinal direction is any value of 7%, 7.5%, 8%, or a range of any two of these values.

[0177] The elongation of the positive electrode sheet along its length can be tested using any method known in the art. As an example, take the positive electrode sheet before cold pressing, cut a 1m length, mark the two ends, adjust the pressure to the target compaction density, and after cold pressing, record the distance between the two ends of the positive electrode sheet as L. The elongation of the electrode sheet is (L-1) / 1*100%.

[0178] Within the above-mentioned range, the elongation of the electrode in the longitudinal direction is increased, improving the flexibility of the electrode, reducing the possibility of brittle fracture during electrode winding or hot pressing, and improving the performance of the electrode.

[0179] In some embodiments, the coating surface density of the positive electrode film is 21.5 mg / cm². 2 -32.5mg / cm 2 In some embodiments, the coating areal density of the positive electrode film is 21.5 mg / cm³. 2 24mg / cm 2 26mg / cm 2 28mg / cm 2 30mg / cm 2 32mg / cm 2 32.5 mg / cm 2Any value in or a range consisting of any two values ​​in it.

[0180] The areal density of the positive electrode film layer is tested using any method known in the art. As an example, the areal density of the positive electrode film layer is determined by measuring the coating weight (g) and coating area (cm²) of the positive electrode film layer on one side. 2 (The number of sampling points is greater than 14). Specifically, the coating density of the positive electrode film is calculated as: coating weight of the positive electrode film on one side (g) / coating area of ​​the positive electrode film (cm²). 2 ).

[0181] The surface density of the positive electrode film within the above range can increase the specific capacity of the electrode and the energy density of the battery.

[0182] In some embodiments, the compaction density of the positive electrode sheet is 3.5 g / cm³. 3 -3.8g / cm 3 In some embodiments, the compaction density of the positive electrode sheet is 3.5 g / cm³. 3 3.6g / cm 3 3.7g / cm 3 3.8g / cm 3 Any value in or a range consisting of any two values ​​in it.

[0183] The compaction density of the positive electrode sheet can be tested using any method known in the art. As an example, the compaction density PD of the positive electrode sheet is determined by measuring the areal density (g / cm³) of the positive electrode film layer on one side. 2 The density is determined by the thickness of the positive electrode film on one side (cm) (number of sampling points > 14). Specifically, the compaction density PD of the positive electrode sheet = the density of the positive electrode film layer on one side (g / cm³). 2 ) / Positive electrode film thickness (cm).

[0184] Within the above-mentioned range, the compaction density of the positive electrode sheet can increase the specific capacity of the electrode sheet and thus increase the energy density of the battery.

[0185] The positive electrode active material layer may also include a conductive agent to improve the conductivity of the positive electrode. The conductive agent may be one or more of SuperP, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers.

[0186] The positive electrode active material layer may also include a binder to firmly bond the positive electrode active material and optional conductive agent to the positive electrode current collector. The binder may be at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0187] The positive electrode current collector can be made of conductive carbon sheet, metal foil, carbon-coated metal foil, porous metal plate, or composite current collector. The conductive carbon material of the conductive carbon sheet can be selected from one or more of Super P, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, carbon-coated metal foil, and porous metal plate can be independently selected from at least one of copper, aluminum, nickel, and stainless steel. The composite current collector can be a composite current collector formed by combining metal foil with a polymer base film.

[0188] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0189] [Negative electrode plate]

[0190] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0191] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0192] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0193] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0194] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0195] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0196] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0197] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0198] [Electrolytes]

[0199] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0200] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0201] In some embodiments, the electrolyte salt may 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0202] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0203] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0204] [Isolation membrane]

[0205] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0206] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0207] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0208] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0209] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0210] [Rechargeable Battery]

[0211] In some implementations, the energy density of the secondary battery is 360-510 Wh / kg.

[0212] In some embodiments, the energy density of the secondary battery is any value or a range of any two of the following: 360Wh / kg, 380Wh / kg, 400Wh / kg, 420Wh / kg, 440Wh / kg, 460Wh / kg, 480Wh / kg, 500Wh / kg, and 510Wh / kg.

[0213] The energy density of the secondary battery was tested using any method known in the art. As an example, the battery cell was left to stand at 25°C for 2 hours to ensure the cell temperature remained at 25°C. At 25°C, the cell was charged at 0.1C to the charging cutoff voltage, and then continued to be charged at this cutoff voltage under constant voltage until the current reached 0.05C, at which point charging was stopped (where C represents the rated capacity of the battery cell). The battery cell was then left to stand at 25°C for 1 hour. At 25°C, the cell was discharged at 0.1C to the discharge cutoff voltage, and the total discharge capacity C0 and total discharge energy E0 of the cell were recorded.

[0214] Battery cell weight measurement: Place the battery cell on an electronic balance until the weight stabilizes, and read the battery cell weight value M0.

[0215] Energy density calculation: The energy density of a battery cell is calculated as the discharge energy E0 of the battery cell divided by the weight M0 of the battery cell.

[0216] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 Here is an example of a square-structured secondary battery, 5. Figure 2 This is an exploded view of secondary battery 5.

[0217] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly 52 via a winding or stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. A non-Newtonian fluid electrolyte composition is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0218] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0219] Figure 3 This is battery module 3, shown as an example. (See reference...) Figure 3 In battery module 3, multiple secondary batteries 5 can be arranged sequentially along the length of battery module 3. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary batteries 5 can be fixed in place using fasteners.

[0220] Optionally, the battery module 3 may also include a housing with a receiving space in which a plurality of secondary batteries 5 are received.

[0221] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0222] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0223] [Electrical appliances]

[0224] In one embodiment of this application, an electrical device is provided, including at least one of a secondary battery, a battery module, or a battery pack according to any embodiment.

[0225] Electrical devices include at least one of the secondary batteries, battery modules, or battery packs provided in this application. The secondary batteries, battery modules, or battery packs can be the power source of the electrical device or the energy storage unit of the electrical device. Electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0226] As an electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0227] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0228] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0229] Example

[0230] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0231] Example 1

[0232] 1) Preparation of aggregate materials

[0233] First aggregate: Lithium hydroxide, Ni 0.94 Co 0.05 Mn 0.01 (OH)₂ was mixed evenly in a mixer and sintered at 750°C for 20 hours in an oxygen atmosphere to obtain the first agglomerate. Lithium hydroxide and Ni were added in this mixture. 0.94 Co 0.05 Mn 0.01 The molar ratio of (OH)2 is 1.04:1.

[0234] Second aggregate: Lithium hydroxide, Ni 0.93 Co 0.05 Mn 0.02 (OH)₂ was mixed evenly in a mixer and sintered at 800°C for 20 hours in an oxygen atmosphere to obtain a second agglomerate. The lithium hydroxide and Ni were added in this mixture. 0.93 Co 0.05 Mn 0.02 The molar ratio of (OH)2 is 1.05:1.

[0235] The first aggregate and the second aggregate were mixed in a mass ratio of 7:3 to form the aggregate material.

[0236] 2) Preparation of positive electrode sheet

[0237] The agglomerate material prepared in Example 1 was placed in a 5L stirred tank, and the conductive agent acetylene black (SP) and the binder polyvinylidene fluoride (PVDF) were added and premixed for 30 minutes. Then, the solvent N-methylpyrrolidone (NMP) was added and the mixture was rapidly stirred under vacuum to form a slurry. The mass ratio of agglomerate material:acetylene black:polyvinylidene fluoride was 96:2:2, and the solid content of the slurry was 70%. The slurry was uniformly coated on both sides onto a 12μm thick positive electrode current collector, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0238] 3) Preparation of negative electrode sheet

[0239] The negative electrode active materials, artificial graphite and hard carbon, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are thoroughly mixed in a deionized water solvent system at a weight ratio of 90:5:2:2:1. The mixture is then coated onto copper foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0240] Graphite (the negative electrode active material), silicon carbide, carbon black (SP), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were dissolved in deionized water at a weight ratio of 90:4:4:2. The mixture was stirred to obtain a uniformly dispersed negative electrode slurry. This slurry was then evenly coated onto the surface of a copper foil current collector. After drying, cold pressing, and cutting, the negative electrode sheet was obtained. Based on the total mass of graphite and silicon carbide, silicon carbide accounted for 30% of the total mass.

[0241] 4) Diaphragm

[0242] Polypropylene film is used as the separator.

[0243] 5) Preparation of electrolyte

[0244] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), the organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed evenly at a volume ratio of 3 / 7. LiPF6 lithium salt was then added and dissolved in the organic solvent and stirred evenly to obtain an electrolyte of 12.5% ​​by mass of LiPF6 lithium salt, thus obtaining the electrolyte of Example 1.

[0245] 6) Battery manufacturing

[0246] The positive electrode, separator, and negative electrode of Example 1 are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The cells are then wound to obtain a bare cell, tabs are welded to the bare cell, and the bare cell is placed in an aluminum shell. The shell is then baked at 80°C to remove water, followed by the injection of electrolyte and sealing to obtain a non-charged battery.

[0247] The uncharged battery then undergoes a series of processes including settling, hot and cold pressing, formation, shaping, and capacity testing to obtain the lithium-ion battery product of Example 1.

[0248] The preparation parameters in Examples 2 to 20 and Comparative Examples 1 to 3 are basically the same as those in Example 1. The specific parameters are shown in Table 1 and Table 2.

[0249] II. Testing Methods

[0250] 1. Characterization of positive electrode active materials

[0251] 1) Confirmation of the chemical formulas of the aggregate material, the first aggregate, and the second aggregate.

[0252] The proportion of each element in the sample is determined by using an inductively coupled plasma spectrometer (ICP) (e.g., Spectroblue type) to determine the chemical formula of the sample.

[0253] 2) Primary particle size of agglomerated materials, first agglomerate, and second agglomerate

[0254] SEM testing was employed: After cold-pressing the sample, it was cut open using an Ar particle beam to expose the end face, and images of the end face were acquired using a scanning electron microscope (SEM). The size of the primary particles in the sample was measured based on the SEM images. At least three samples were measured, with at least 50 data points for each sample. The average of these data points was taken as the primary particle size of the sample.

[0255] 3) Aggregate material, first aggregate, second aggregate D V 50 and (Dv90-Dv10) / Dv50

[0256] Volumetric particle sizes Dv10, Dv50, and Dv90 are well-known concepts in the art. Specifically, Dv10 refers to the particle size that, in a volumetric particle size distribution, reaches 10% of the total volume from the smallest particle size side, typically expressed in μm. Dv50 refers to the particle size that, in a volumetric particle size distribution, reaches 50% of the total volume from the smallest particle size side. Dv90 refers to the particle size that, in a volumetric particle size distribution, reaches 90% of the total volume from the smallest particle size side.

[0257] The test methods for particle volume distribution sizes Dv10, Dv50, and Dv90 described above can be performed using methods known in the art. For example, particle size distribution can be determined using a Malvern 3000 instrument, in accordance with GB / T 19077-2016 / ISO 13320:2009, laser diffraction method.

[0258] 4) Peak position of the single peak in the particle size distribution map

[0259] Particle size distribution was determined using laser diffraction method according to GB / T 19077-2016 / ISO 13320:2009, with the Malvern 3000 instrument. A particle size distribution map based on volume distribution was obtained, and the position of the single peak was determined from the particle size distribution map.

[0260] 5) Specific surface area of ​​aggregate materials

[0261] The BET method for determining specific surface area can be used with methods known in the art. As an example, GB / T 19587-2017 "Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method" can be referred to, and the determination can be performed using the TriStar II 3020 equipment.

[0262] 2. Positive electrode plate

[0263] 1) Coating surface density of the positive electrode film

[0264] The areal density of the positive electrode film is determined by measuring the coating weight (g) and coating area (cm²) of the positive electrode film on one side. 2 (The number of sampling points is greater than 14). Specifically, the coating density of the positive electrode film is calculated as: coating weight of the positive electrode film on one side (g) / coating area of ​​the positive electrode film (cm²). 2 ).

[0265] 2) Compacted density of the positive electrode sheet

[0266] The compaction density (PD) of the positive electrode sheet is determined by measuring the areal density (g / cm²) and thickness (cm) of the positive electrode film layer on one side (number of sampling points > 14). Specifically, the compaction density (PD) of the positive electrode sheet = areal density (g / cm²) of the positive electrode film layer on one side. 2 ) / Positive electrode film thickness (cm).

[0267] 3) Elongation of the positive electrode sheet in the longitudinal direction

[0268] Take the positive electrode sheet before cold pressing, cut a 1m length, mark the two ends, adjust the pressure to the target compaction density, after cold pressing, take the positive electrode sheet and record the distance between the two ends as L, the elongation of the electrode sheet is (L-1) / 1*100%.

[0269] 3. Battery

[0270] 1) Battery mass energy density

[0271] Battery cell capacity testing: The battery cell was left to stand at 25°C for 2 hours to ensure the temperature remained at 25°C. At 25°C, the battery cell was charged at 0.1C to the charging cutoff voltage, and then continued to be charged at this cutoff voltage under constant voltage until the current reached 0.05C, at which point charging was stopped (where C represents the rated capacity of the battery cell). The battery cell was then left to stand at 25°C for 1 hour. At 25°C, the battery cell was discharged at 0.1C to the discharge cutoff voltage, and the total discharge capacity C0 and total discharge energy E0 of the battery cell were recorded.

[0272] Battery cell weight measurement: Place the battery cell on an electronic balance until the weight stabilizes, and read the battery cell weight value M0.

[0273] Energy density calculation: The energy density of a battery cell is calculated as the discharge energy E0 of the battery cell divided by the weight M0 of the battery cell.

[0274] 2) The battery discharges at 4.5C when it is at 40% SOC.

[0275] The battery cells were discharged at a constant current of 0.33C to 2.8V and allowed to stand for 30 minutes; then charged at a constant current of 0.33C to 4.25V and then charged at a constant voltage of 0.05C until the voltage stabilized, and allowed to stand for 30 minutes; discharged at a constant current of 0.33C to 2.8V, at which point the initial capacity C0 was read, and allowed to stand for 30 minutes; charged at a constant current of 0.33C to 4.25V and then charged at a constant voltage of 0.05C until the voltage stabilized, and allowed to stand for 30 minutes; discharged at a constant current of 0.33C to 0.4C0Ah (40%) SOC and allowed to stand for 60 minutes; discharged at a constant current of 4.5C to 2.8V, and the discharge time was recorded.

[0276] III. Analysis of Test Results for Each Embodiment and Comparative Example

[0277] Batteries for each embodiment and comparative example were prepared according to the above method, and various performance parameters were measured. The results are shown in Tables 1, 2 and 3 below.

[0278] Table 1

[0279]

[0280]

[0281]

[0282]

[0283] Table 3

[0284]

[0285]

[0286] Based on the above results, the positive electrode active materials in Examples 1-20 include aggregate materials with the chemical formula LiNi. 0.937 Co 0.05 Mn 0.013 O2, LiNi 0.9375 Co 0.04 Mn 0.0225 O2, LiNi 0.9375 Co 0.0475 Mn 0.015 O2, LiNi 0.948 Co 0.042 Mn 0.01 O2, LiNi 0.95 Co 0.033 Mn 0.017 O2, LiNi 0.959 Co 0.039 Mn 0.002 O2, LiNi 0.96 Co 0.02 Mn 0.02 O2,

[0287] LiNi 0.967 Co 0.02 Mn 0.013 O2, LiNi 0.967 Co 0.0255 Mn 0.0075 O2, LiNi 0.95 Co 0.037 Mn 0.013 O2, LiNi 0.953 Co 0.033 Mn 0.014 O2, LiNi 0.96 Co 0.033 Mn 0.007 O2, LiNi 0.951 Co 0.029 Mn 0.02 O2, LiNi 0.936 Co 0.046 Mn 0.018 O2, LiNi 0.94 Co 0.04 Mn 0.02 O2, LiNi 0.94 Co 0.05 Mn 0.01 O2, LiNi 0.942 Co 0.044 Mn 0.014 O2, LiNi 0.945 Co 0.0325 Mn 0.0225 O2, LiNi 0.954Co 0.04 Mn 0.006 O2 or LiNi 0.955 Co 0.0275 Mn 0.0175 O2, the primary particle size of the aggregated material is 100-600 nm, and the particle size distribution of the aggregated material satisfies (Dv90-Dv10) / Dv50≥1.6.

[0288] As can be seen from the comparison between Examples 1-20 and Comparative Examples 1-3, the primary particle size of the agglomerate material is 100-600 nm, and the particle size distribution of the agglomerate material satisfies (Dv90-Dv10) / Dv50≥1.6, which can improve the compaction density of the electrode, improve the energy density of the battery, and the battery has excellent rate performance, meeting the requirements for the use of new batteries.

[0289] As can be seen from the comparison between Examples 8-10 and Examples 6-7, the primary particle size of the agglomerate material is 200-500 nm, which can further improve the energy density of the battery.

[0290] As can be seen from Examples 1 to 20, the particle size Dv50 of the agglomerate material is 6-15 μm, the electrode has high compaction density and low elongation, the battery has high energy density and excellent rate performance, and the overall electrochemical performance of the battery is improved.

[0291] As can be seen from the comparison between Examples 12, 14-16, 18-20 and Examples 11, 13, 17, the particle size Dv50 of the agglomerate material is 7-13 μm, which can further improve the energy density of the battery, and the battery has excellent rate performance.

[0292] As can be seen from Examples 1 to 20, the particle size distribution of the agglomerate material determined by particle size analysis laser diffraction is single-peaked, with the peak position located at 6-15 μm. The electrode has high areal density and low elongation, and the battery has high energy density and excellent rate performance, thus comprehensively improving the electrochemical performance of the battery.

[0293] As can be seen from the comparison between Examples 12, 14-16, 18-20 and Examples 11, 13, 17, the particle size distribution of the agglomerate material determined by the particle size analysis laser diffraction method is unimodal, with the peak position located at 7-13 μm, which can further improve the energy density of the battery, and the battery has excellent rate performance.

[0294] As can be seen from Examples 1 to 20, the particle size distribution of the agglomerate material satisfies 1.6≤(Dv90-Dv10) / Dv50≤2.3, the electrode has high areal density and low elongation, the battery has high energy density and excellent rate performance, and the overall electrochemical performance of the battery is improved.

[0295] A comparison between Examples 4 and 5 shows that the particle size distribution of the agglomerate material satisfies 1.8≤(Dv90-Dv10) / Dv50≤2.1, which can further improve the energy density of the battery.

[0296] As can be seen from Examples 1-20, the specific surface area of ​​the aggregate material is 0.5 m². 2 / g-0.9m 2 / g can give the electrode high areal density and low elongation, and the battery high energy density and excellent rate performance, thus comprehensively improving the electrochemical performance of the battery.

[0297] As can be seen from Examples 1 to 20, the elongation of the positive electrode sheet in the longitudinal direction is 7% to 8%, and the electrode sheet has a low elongation, which improves the processing performance of the electrode sheet.

[0298] As shown in Examples 1-20, the coating surface density of the positive electrode film is 21.5 mg / cm². 2 -32.5mg / cm 2 The electrodes have high areal density, and the battery has high energy density.

[0299] As shown in Examples 1-20, the compaction density of the positive electrode sheet is 3.5 g / cm³. 3 -3.8g / cm 3 The electrode has a high compaction density, and the battery has a high energy density.

[0300] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A positive electrode active material, characterized in that, The positive electrode active material includes an agglomerate material, the chemical formula of which is Li. a Ni x Co y M 1-x-y O 2-b Where 0.6≤a≤1.2, 0.6≤x≤1, 0≤y≤0.4, -0.1≤b≤0.1, and M includes one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, and Mo; the primary particle size of the agglomerate material is 100~600nm, and the particle size distribution of the agglomerate material satisfies (Dv90-Dv10) / Dv50≥1.

6.

2. The positive electrode active material according to claim 1, characterized in that, The chemical formula Li a Ni x Co y M 1-x-y O 2-b In the given condition, 0.6≤a≤1.2, 0.8≤x≤1, 0≤y≤0.2, and -0.1≤b≤0.

1.

3. The positive electrode active material according to claim 2, characterized in that, The chemical formula Li a Ni x Co y M 1-x-y O 2-b In the given condition, 0.8≤a≤1.2, 0.93≤x≤0.98, 0≤y≤0.07, and -0.1≤b≤0.

1.

4. The positive electrode active material according to any one of claims 1 to 3, characterized in that, The primary particle size of the agglomerate material is 200-500 nm.

5. The positive electrode active material according to any one of claims 1 to 4, characterized in that, The particle size Dv50 of the agglomerate material is 6-15 μm.

6. The positive electrode active material according to claim 5, characterized in that, The particle size Dv50 of the agglomerate material is 7-13 μm.

7. The positive electrode active material according to any one of claims 1 to 6, characterized in that, The particle size distribution of the aggregated material was determined by laser diffraction, and it was found to be unimodal with the peak position located at 6-15 μm.

8. The positive electrode active material according to claim 7, characterized in that, The particle size distribution of the aggregated material was determined by laser diffraction, and it was found to be unimodal with the peak located between 7 and 13 μm.

9. The positive electrode active material according to any one of claims 1 to 8, characterized in that, The particle size distribution of the agglomerate material satisfies 1.6≤(Dv90-Dv10) / Dv50≤2.

3.

10. The positive electrode active material according to claim 9, characterized in that, The particle size distribution of the agglomerate material satisfies 1.8≤(Dv90-Dv10) / Dv50≤2.

1.

11. The positive electrode active material according to any one of claims 1 to 10, characterized in that, The specific surface area of ​​the aggregate material is 0.5-0.9 m². 2 / g.

12. The positive electrode active material according to any one of claims 1 to 11, characterized in that, The agglomerate material includes a first agglomerate and a second agglomerate, wherein the particle size Dv50 of the first agglomerate is 9-15 μm and the particle size Dv50 of the second agglomerate is 4-8 μm.

13. The positive electrode active material according to claim 12, characterized in that, The chemical formula of the first aggregate is Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 The chemical formula of the second aggregate is Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2 x1≥x2, Where 0.6≤a1≤1.2, 0.6≤x1≤1, 0≤y1≤0.4, -0.1≤b1≤0.1, 0.6≤a2≤1.2, 0.4≤x2≤1, 0≤y2≤0.6, -0.1≤b2≤0.1, and M1 and M2 each independently include one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, and Mo.

14. The positive electrode active material according to claim 13, characterized in that, The chemical formula of the first aggregate is Li a1 Ni x1 Co y1 M1 1-x1-y1 O 2-b1 In the given condition, 0.8≤a1≤1.2, 0.94≤x1≤0.98, 0≤y1≤0.06, and -0.1≤b1≤0.

1.

15. The positive electrode active material according to claim 13 or 14, characterized in that, The chemical formula of the second aggregate is Li a2 Ni x2 Co y2 M2 1-x2-y2 O 2-b2 In the given equation, 0.8≤a²≤1.2, 0.93≤x²≤0.96, 0≤y²≤0.07, and -0.1≤b²≤0.

1.

16. The positive electrode active material according to any one of claims 12 to 15, characterized in that, The primary particle size of the first agglomerate is larger than that of the second agglomerate.

17. The positive electrode active material according to any one of claims 12 to 16, characterized in that, The primary particle size of the first agglomerate is 100-1000 nm, and the primary particle size of the second agglomerate is 100-300 nm.

18. The positive electrode active material according to any one of claims 12 to 17, characterized in that, The particle size distribution of the first aggregate and the second aggregate satisfies (Dv90-Dv10) / Dv50≤1.

50.

19. The positive electrode active material according to any one of claims 12 to 18, characterized in that, The particle size distribution of the first agglomerate satisfies 0.50≤(Dv90-Dv10) / Dv50≤1.30, and the particle size distribution of the second agglomerate satisfies 1.30≤(Dv90-Dv10) / Dv50≤1.

50.

20. The positive electrode active material according to any one of claims 12 to 19, characterized in that, The mass ratio of the first aggregate to the second aggregate is 1:1 to 9:

1.

21. A positive electrode sheet, comprising a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, said positive electrode film layer comprising the positive electrode active material according to any one of claims 1 to 20.

22. The positive electrode sheet according to claim 21, characterized in that, The mass content of the positive electrode active material is 95%~99.5%, based on the total mass of the positive electrode film.

23. The positive electrode sheet according to claim 21 or 22, characterized in that, The elongation of the positive electrode sheet in the longitudinal direction is 7%~8%.

24. The positive electrode sheet according to any one of claims 21 to 23, characterized in that, The areal density of the positive electrode film is 21.5 mg / cm³. 2 -32.5mg / cm 2 。 25. The positive electrode sheet according to any one of claims 21 to 24, characterized in that, The compaction density of the positive electrode sheet is 3.5 g / cm³. 3 -3.8 g / cm 3 .

26. A secondary battery, characterized in that, Includes a positive electrode sheet, wherein the positive electrode sheet is the positive electrode sheet according to any one of claims 21 to 25.

27. The secondary battery according to claim 26, characterized in that, The secondary battery includes a lithium-ion battery.

28. An electrical appliance, characterized in that, Includes the secondary battery as described in claim 26 or 27.

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