Lithium-ion battery positive electrode sheet, lithium-ion battery comprising same, and electric device

Abstract

This application provides a positive electrode sheet for a lithium-ion battery, comprising a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer comprises a mixture of positive active materials consisting of: first positive active material polycrystalline particles with a particle size of 11.0–20.0 μm; second positive active material polycrystalline particles with a particle size of 6.0–10.5 μm; and third positive active material single crystal particles with a particle size of 1.1–5.2 μm. The number of first positive active material polycrystalline particles is 'a', the number of second positive active material polycrystalline particles is 'b', and the number of third positive active material single crystal particles is 'c', with (a+b)∶c ranging from 5.7∶4.3 to 7.7∶2.3. This application also provides a lithium-ion battery, a battery module, a battery pack, and a power-consuming device comprising this positive electrode sheet.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to a lithium-ion battery positive electrode, a lithium-ion battery comprising the same, and an electrical device thereof. Background Technology

[0002] In recent years, with the increasingly widespread application of lithium-ion batteries, they have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other fields. Due to the significant development of lithium-ion batteries, higher requirements have been placed on their energy density and processing performance.

[0003] The compaction density of the positive electrode active material in existing lithium-ion battery positive electrode sheets still falls short of its ultimate compaction density. Simply increasing the roller pressure to improve the compaction density may result in excessive elongation of the electrode sheet under high active material loading. Excessive elongation can lead to brittle fracture during winding or hot pressing. Therefore, it is still necessary to develop lithium-ion battery positive electrode sheets that achieve both low elongation and high compaction density under high active material loading. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode sheet for lithium-ion batteries that can achieve high electrode compaction density with low electrode elongation even with a high active material loading.

[0005] To achieve the above objectives, a first aspect of this application provides a positive electrode sheet for a lithium-ion battery, comprising a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer comprising a mixture of positive electrode active materials composed of the following substances:

[0006] Polycrystalline particles of the first positive electrode active material with a particle size of 11.0–20.0 μm;

[0007] Polycrystalline particles of the second positive electrode active material with a particle size of 6.0–10.5 μm; and

[0008] Single-crystal particles of the third positive electrode active material with a particle size of 1.1–5.2 μm.

[0009] Wherein, the number of polycrystalline particles of the first positive electrode active material is a, the number of polycrystalline particles of the second positive electrode active material is b, and the number of single crystal particles of the third positive electrode active material is c, and (a+b):c is in the range of 5.7:4.3 to 7.7:2.3.

[0010] Therefore, this application combines three positive electrode active materials with different particle sizes in a specific ratio, so that the positive electrode sheet can still obtain high compaction density under high positive electrode material loading and low elongation.

[0011] In any embodiment, (a+b):c is in the range of 6.1:3.9 to 7.2:2.8. By further selecting the ratio of the three positive electrode active material particles, the compaction density of the positive electrode sheet can be further improved.

[0012] In any embodiment, the first polycrystalline positive electrode material, the second polycrystalline positive electrode material, and the third single-crystal positive electrode material are all ternary positive electrode active materials. Optionally, the first polycrystalline positive electrode material, the second polycrystalline positive electrode material, and the third single-crystal positive electrode material may have the same or different chemical compositions, and all of them have the chemical formula LiNi. a Co b M (1-a-b) O2, where: 0.8≤a<1.0, 0<b<0.2, and a+b<1.0, and M is selected from one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, and Nb. By selecting ternary materials as the positive electrode active material and choosing specific chemical compositions, it is beneficial to obtain higher specific capacity and initial coulombic efficiency, as well as battery cycle life.

[0013] In any embodiment, the pore volume of the positive electrode film is 1.2 mm. 3 / g~4.0mm 3 Within the range of / g. By controlling the pore volume of the positive electrode film, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0014] In any embodiment, the shear stress of the positive electrode sheet is in the range of 0.65 MPa to 0.85 MPa. Such a positive electrode sheet can ensure good toughness after stretching under high rolling pressure and is not prone to brittle fracture.

[0015] In any embodiment, in the positive electrode active material mixture, the first positive electrode active material polycrystalline particles have a Dv50 of 12–16 μm and a total mass of A; the second positive electrode active material polycrystalline particles have a Dv50 of 8–10 μm and a total mass of B; the third positive electrode active material single crystal particles have a Dv50 of 2.5–4 μm and a total mass of C; (A+B):C is in the range of 6:4–8:2, optionally in the range of 6.5:3.5–7.5:2.5. By controlling the mass ratio of these three positive electrode active material particles, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0016] In any embodiment, the compaction density (CPD-1T) of the positive electrode active material mixture under 1 ton of pressure is 3.0 g / cm³. 3 ~3.2g / cm 3 Within the above range. By controlling the compaction density of the positive electrode active material mixture under 1 ton of pressure within the above range, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0017] In any embodiment, the BET specific surface area of ​​the positive electrode active material mixture is 0.5 m². 2 / g~0.7m 2 Within the range of / g. By controlling the BET specific surface area of ​​the positive electrode active material mixture within the above range, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0018] In any embodiment, the SPAN value of the positive electrode active material mixture is in the range of 1.70 to 2.20, where SPAN = (Dv90 - Dv10) / Dv50. By controlling the SPAN value of the positive electrode active material mixture within the above range, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0019] In any embodiment, the Dv99 of the positive electrode active material mixture is in the range of 18 μm to 21 μm. By controlling the Dv99 of the positive electrode active material mixture within the above range, the compaction density of the positive electrode sheet can be improved.

[0020] In any embodiment, the SPAN value of the first positive electrode active material polycrystalline particles satisfies SPAN ≤ 1.20, and optionally, 0.50 ≤ SPAN ≤ 1.00. By controlling the SPAN value of the first positive electrode active material polycrystalline particles within the above range, sufficient filling space can be provided and a higher specific capacity can be achieved for the positive electrode sheet.

[0021] In any embodiment, the SPAN value of the second positive electrode active material polycrystalline particles satisfies SPAN ≥ 1.20, and optionally, 1.30 ≤ SPAN ≤ 1.50. By controlling the SPAN value of the second positive electrode active material polycrystalline particles within the above range, the pores and spaces can be fully filled, thereby increasing the compaction density of the positive electrode sheet.

[0022] In any embodiment, the SPAN value of the third positive electrode active material single crystal particles satisfies SPAN ≤ 1.70, and optionally, 1.10 ≤ SPAN ≤ 1.40. By controlling the SPAN value of the third positive electrode active material single crystal particles within the above range, higher compressive strength can be provided for the positive electrode sheet.

[0023] In any embodiment, the tap density (TPD) of the third positive electrode active material single crystal particles is ≤1.8 g / cm³. 3 Optionally, 1.2 g / cm³ 3 ≤TPD≤1.5g / cm 3 When the tap density of the single crystal particles of the third positive electrode active material is within the above range, it has a highly dispersed morphology, which can further improve the space utilization of the positive electrode sheet and increase the compaction density of the electrode sheet.

[0024] A second aspect of this application also provides a lithium-ion battery, which includes the positive electrode sheet of the first aspect of this application.

[0025] A third aspect of this application provides a battery module including the lithium-ion battery of the second aspect of this application.

[0026] A fourth aspect of this application provides a battery pack that includes the battery module of the third aspect of this application.

[0027] The fifth aspect of this application provides an electrical device including at least one selected from the second aspect of this application, the third aspect of this application, or the fourth aspect of this application. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the positive electrode sheet of Example 1.

[0029] Figure 2 This is a schematic diagram of a lithium-ion battery according to one embodiment of this application.

[0030] Figure 3 yes Figure 2 An exploded view of a lithium-ion battery according to an embodiment of this application is shown.

[0031] Figure 4 This is a schematic diagram of a battery module according to one embodiment of this application.

[0032] Figure 5 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0033] Figure 6 yes Figure 5 An exploded view of a battery pack according to one embodiment of this application is shown.

[0034] Figure 7 This is a schematic diagram of an electrical device using a lithium-ion battery as a power source according to an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Lithium-ion battery; 51 Casing; 52 Electrode assembly; 53 Top cover assembly Detailed Implementation

[0037] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the lithium-ion battery positive electrode sheet, the lithium-ion battery comprising it, the battery module, the battery pack, and the power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0038] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0039] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0040] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0041] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0042] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0043] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: 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).

[0044] To achieve high cell mass and volumetric energy density, two approaches can be taken: increasing the specific capacity of the positive electrode active material and increasing the compaction density of the positive electrode sheet under high active material loading. However, simply increasing the roller pressure to improve the compaction density of the positive electrode sheet can easily lead to particle crushing and slippage of the positive electrode active material, resulting in a large elongation of the positive electrode sheet, such as greater than or equal to 0.8%. Excessive elongation can cause brittle fracture during winding or hot pressing. Therefore, it is still necessary to develop lithium-ion battery positive electrode sheets with low elongation and high compaction density under high active material loading.

[0045] The inventors of this application have discovered that when two types of polycrystalline positive electrode active materials with specific particle size ranges are mixed with one type of single-crystal positive electrode active material with specific particle size range in a specific ratio as positive electrode active materials, the resulting positive electrode sheet can achieve high solid density at low elongation.

[0046] In this application, the terms "single crystal" and "polycrystalline" have the common meaning in the field of cathode active material technology. Generally speaking, polycrystalline cathode active material particles refer to spherical aggregates formed by the accumulation of a large number of small crystallites, while single crystal cathode active material particles refer to monomers or aggregates formed by a single or several small crystallites with clear boundaries. "Single crystal" and "polycrystalline" can be confirmed by methods known in the art, such as observing the particle morphology by scanning electron microscopy.

[0047] In one embodiment of this application, a positive electrode sheet for a lithium-ion battery is provided, comprising a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, wherein the positive electrode film layer comprises a mixture of positive electrode active materials composed of the following substances:

[0048] Polycrystalline particles of the first positive electrode active material with a particle size of 11.0–20.0 μm;

[0049] Polycrystalline particles of the second positive electrode active material with a particle size of 6.0–10.5 μm; and

[0050] Single-crystal particles of the third positive electrode active material with a particle size of 1.1–5.2 μm.

[0051] Wherein, the number of polycrystalline particles of the first positive electrode active material is a, the number of polycrystalline particles of the second positive electrode active material is b, and the number of single crystal particles of the third positive electrode active material is c, and (a+b):c is in the range of 5.7:4.3 to 7.7:2.3.

[0052] In this application, particle size refers to the distance between the two furthest points on a particle in a scanning electron microscope (SEM) image. Particle size can be measured using equipment and methods known in the art. For example, a scanning electron microscope (e.g., ZEISS Sigma 300) can be used to obtain a scanning electron microscope image of the positive electrode sheet, referring to JY / T010-1996.

[0053] In this application, the number of particles is determined by randomly selecting 10 regions on the positive electrode sheet and taking SEM images of each region. The number of particles within the specified particle size range in each test region is counted from the SEM images, and the average number of particles in each test region is calculated.

[0054] Although the mechanism is not yet clear, the applicant unexpectedly discovered that by combining two polycrystalline positive electrode active materials with different particle sizes and one single-crystal positive electrode active material in a specific ratio, the porosity and volume utilization between particles can be significantly improved, thereby enhancing the compressive strength of the positive electrode sheet. Therefore, the positive electrode sheet can still achieve high compaction density at low elongation even with a high positive electrode active material loading. Not wanting to be confined by theory, it is now considered that the first positive electrode active material polycrystalline particles with a particle size of 11.0–20.0 μm serve as the framework of the positive electrode film. Excessively large particle sizes can easily lead to cracks at the particle edges and limit the specific capacity, while excessively small particle sizes offer no framework effect. The second positive electrode active material polycrystalline particles with a particle size of 6.0–10.5 μm serve as a primary filler, improving space utilization and simultaneously enhancing the specific capacity. Single-crystal particles of the third cathode active material, with a particle size of 1.1–5.2 μm, are used as a secondary filler. Due to their high dispersibility and compressive strength, they can fully fill the pores left by the polycrystalline particles of the first and second cathode active materials. Furthermore, setting the ratio of the three materials (a+b):c within the range of 5.7:4.3 to 7.7:2.3 maximizes the balance between specific capacity and compaction density. Such dense packing is less prone to particle displacement / slippage under high pressure, thus preventing excessive electrode stretching and increased brittleness. If the ratio is too small, it will affect the battery capacity; if it is too large, it will be difficult to improve the compaction density.

[0055] In some embodiments, (a+b):c is in the range of 6.1:3.9 to 7.2:2.8, for example, 6.2:3.8. By further selecting the ratio of the three positive electrode active material particles, the compaction density of the positive electrode sheet can be further improved.

[0056] The ratio between the number of polycrystalline particles a of the first positive electrode active material and the number of polycrystalline particles b of the second positive electrode active material can be arbitrarily selected by those skilled in the art according to actual needs. For example, a:b can be in the range of 1:9 to 7.5:2.5.

[0057] The first polycrystalline positive electrode active material, the second polycrystalline positive electrode active material, and the third single-crystal positive electrode active material may have the chemical composition of conventional positive electrode active materials in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0058] In some embodiments, the first polycrystalline positive electrode material, the second polycrystalline positive electrode material, and the third single-crystal positive electrode material are all ternary positive electrode active materials. Optionally, the first polycrystalline positive electrode material, the second polycrystalline positive electrode material, and the third single-crystal positive electrode material have the same or different chemical compositions, and all have the chemical formula LiNi. a Co b M (1-a-b) O2, where: 0.8≤a<1.0, 0<b<0.2, and a+b<1.0, and M is selected from one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, and Nb. By selecting ternary materials as the positive electrode active material and choosing specific chemical compositions, it is beneficial to obtain higher specific capacity and initial coulombic efficiency, as well as battery cycle life.

[0059] In some embodiments, the pore volume of the positive electrode film is 1.2 mm. 3 / g~4.0mm 3 Within the range of / g, optionally within 1.2mm 3 / g~2.0mm 3 Within the range of / g. By controlling the pore volume of the positive electrode film, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0060] Pore ​​volume has a meaning known in the art. In this application, the pore volume of the positive electrode film can be measured using methods known in the art. As an example, refer to GB / T 21650.2-2008 / ISO 15901-2:2006 "Determination of pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption method" Part II: Analysis of mesopores and macropores by gas adsorption method, and use an AccuPycⅡ1340 true density meter for measurement.

[0061] In some embodiments, the shear stress of the positive electrode sheet is in the range of 0.65 MPa to 0.85 MPa. Such a positive electrode sheet has a high tensile strength, ensuring good toughness after stretching under high rolling pressure and preventing brittle fracture.

[0062] Shear stress has a meaning known in the art. In this application, shear stress is measured by the following method: Take the electrode to be tested, cut a sample with a width of 0.02m and a length of 0.1m, the edge of the sample having an exposed current collector area for welding the electrode tab; attach a double-sided adhesive tape with a width of 0.02m and a length of 0.09m to a steel plate with a width of 0.02m and a length of 0.2m, wherein one end of the double-sided adhesive tape is flush with one end of the steel plate; attach the electrode sample to the double-sided adhesive tape, with one end of the sample flush with one end of the double-sided adhesive tape; fix a paper strip with a width of 0.02m and a length of 0.15m to the exposed current collector surface of the electrode sample; fix the end of the steel plate without the electrode attached with the lower clamp of the tensile testing machine, fold the paper strip upwards and fix it with the upper clamp, turn on the tensile testing machine, and perform a continuous 180° stretch at a tensile speed of 0.05m / min; record the maximum load displayed by the tensile testing machine when the electrode breaks, which is recorded as the shear stress of the electrode.

[0063] In some embodiments, in the positive electrode active material mixture, the Dv50 of the first positive electrode active material polycrystalline particles is 12-16 μm, for example 12-13 μm or 13-16 μm, and the total mass is A; the Dv50 of the second positive electrode active material polycrystalline particles is 8-10 μm, for example 8-9 μm or 9-10 μm, and the total mass is B; the Dv50 of the third positive electrode active material single crystal particles is 2.5-4 μm, for example 2.5-3 μm or 3-4 μm, and the total mass is C; (A+B):C is in the range of 6:4 to 8:2, and optionally in the range of 6.5:3.5 to 7.5:2.5. By controlling the mass ratio of these three positive electrode active material particles, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0064] The ratio between the total mass A of the first positive electrode active material polycrystalline particles and the total mass B of the second positive electrode active material polycrystalline particles can be arbitrarily selected by those skilled in the art according to actual needs. For example, A:B can be in the range of 2:8 to 7:3.

[0065] In this application, the volume distribution particle size Dv50 of the positive electrode active material particles, as well as Dv10, Dv90, and Dv99 mentioned below, are well-known concepts in the art. Specifically, Dv10 is the particle size that reaches 10% of the total volume from the smallest particle size side in the volume-based particle size distribution. Dv50 is the particle size that reaches 50% of the total volume from the smallest particle size side in the volume-based particle size distribution. Dv90 is the particle size that reaches 90% of the total volume from the smallest particle size side in the volume-based particle size distribution. Dv99 is the particle size that reaches 99% of the total volume from the smallest particle size side in the volume-based particle size distribution. The testing methods for particle volume distribution particle sizes Dv10, Dv50, Dv90, and Dv99 can employ methods well-known in the art. As an example, particle size distribution can be determined using the laser diffraction method according to GB / T 19077-2016 / ISO 13320:2009, with the Malvern 3000 equipment.

[0066] In some embodiments, the compaction density (CPD-1T) of the positive electrode active material mixture under 1 ton of pressure is 3.0 g / cm³. 3 ~3.2g / cm 3 Within the range, optionally at 3.1 g / cm 3 ~3.2g / cm 3 Within the above range. By controlling the compaction density of the positive electrode active material mixture under 1 ton of pressure within the above range, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0067] In this application, the test method for the compaction density (CPD-1T) of the positive electrode active material mixture under 1 ton of pressure can employ methods known in the art. As an example, the determination can be performed using a UTM7305 electronic pressure testing machine, referring to GB / T 5162-2006 "Graphite Anode Materials for Lithium-ion Batteries".

[0068] In some embodiments, the BET specific surface area of ​​the positive electrode active material mixture is 0.5 m². 2 / g~0.7m 2 Within the range of / g, optionally within 0.59m 2 / g~0.63m 2 Within the range of / g. By controlling the BET specific surface area of ​​the positive electrode active material mixture within the above range, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0069] In this application, the BET specific surface area of ​​the positive electrode active material mixture can be determined using 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 referenced, and the determination can be performed using the TriStar II 3020 equipment.

[0070] In some embodiments, the SPAN value of the positive electrode active material mixture is in the range of 1.70 to 2.20, where SPAN = (Dv90 - Dv10) / Dv50. Optionally, the SPAN value of the positive electrode active material mixture is in the range of 1.75 to 2.10. By controlling the SPAN value of the positive electrode active material mixture within the above range, it is possible to ensure that the positive electrode sheet has a high compaction density at low elongation.

[0071] In some embodiments, the Dv99 of the positive electrode active material mixture is in the range of 18 μm to 21 μm, and optionally in the range of 19.5 μm to 21 μm. By controlling the Dv99 of the positive electrode active material mixture within the above range, the compaction density of the positive electrode sheet can be improved.

[0072] In some embodiments, the SPAN value of the first positive electrode active material polycrystalline particles satisfies SPAN ≤ 1.20, and optionally, 0.50 ≤ SPAN ≤ 1.00. By controlling the SPAN value of the first positive electrode active material polycrystalline particles within the above range, sufficient filling space can be provided and a higher specific capacity can be achieved for the positive electrode sheet.

[0073] In some embodiments, the SPAN value of the second positive electrode active material polycrystalline particles satisfies SPAN ≥ 1.20, and optionally, 1.30 ≤ SPAN ≤ 1.50. By controlling the SPAN value of the second positive electrode active material polycrystalline particles within the above range, the pores and spaces can be sufficiently filled, thereby increasing the compaction density of the positive electrode sheet.

[0074] In some embodiments, the SPAN value of the third positive electrode active material single crystal particles satisfies SPAN ≤ 1.70, and optionally, 1.10 ≤ SPAN ≤ 1.40. By controlling the SPAN value of the third positive electrode active material single crystal particles within the above range, higher compressive strength can be provided to the positive electrode sheet, thereby improving the compaction density of the positive electrode sheet.

[0075] In some embodiments, the tap density (TPD) of the third positive electrode active material single crystal particles is ≤1.8 g / cm³. 3 Optionally, 1.2 g / cm³ 3 ≤TPD≤1.5g / cm 3When the tap density of the single crystal particles of the third positive electrode active material is within the above range, it has a highly dispersed morphology, which can further improve the space utilization of the positive electrode sheet and increase the compaction density of the electrode sheet.

[0076] In this application, the test method for the tap density (TPD) of the positive electrode active material particles can be a method known in the art. As an example, GB / T 24533-2009 "Determination of Tap Density of Metal Powders" can be referred to, and the measurement can be performed using a Dandong Baite BT-300 tap density meter.

[0077] In addition, the lithium-ion battery, battery module, battery pack and power device of this application will be described below with appropriate reference to the accompanying drawings.

[0078] In one embodiment of this application, a lithium-ion battery is provided.

[0079] Typically, a lithium-ion battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and extracting. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0080] [Positive electrode plate]

[0081] As defined above, the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector.

[0082] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0083] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0084] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0085] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0086] 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.

[0087] [Negative electrode plate]

[0088] 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.

[0089] 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.

[0090] 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.).

[0091] 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.

[0092] 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).

[0093] 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.

[0094] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0095] 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.

[0096] [Electrolytes]

[0097] 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.

[0098] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] [Isolation membrane]

[0103] In some embodiments, the lithium-ion 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.

[0104] 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.

[0105] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0106] In some embodiments, the lithium-ion battery may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0107] In some implementations, the outer packaging of a lithium-ion battery can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of a lithium-ion 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.

[0108] This application does not impose any particular limitation on the shape of the lithium-ion battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 This is an example of a square-structured lithium-ion battery 5.

[0109] In some implementations, refer to Figure 3 The outer packaging may include a housing 51 and a top cover assembly 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 top cover assembly 53 can cover the opening to close the receiving cavity. Positive electrode sheets, negative electrode sheets, and a separator can be formed into electrode assemblies 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The lithium-ion 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.

[0110] In some implementations, lithium-ion batteries can be assembled into battery modules, and the number of lithium-ion batteries contained in a 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.

[0111] Figure 4 This is battery module 4, used as an example. (See reference...) Figure 4 In battery module 4, multiple lithium-ion batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple lithium-ion batteries 5 can be fixed in place using fasteners.

[0112] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple lithium-ion batteries 5 are housed.

[0113] 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.

[0114] Figure 5 and Figure 6 This is battery pack 1 as an example. (See reference...) Figure 5 and Figure 6 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.

[0115] In addition, this application also provides an electrical device, which includes at least one of the lithium-ion battery, battery module, or battery pack provided in this application. The lithium-ion battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0116] As the electrical device, a lithium-ion battery, battery module, or battery pack can be selected according to its usage requirements.

[0117] Figure 7 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 lithium-ion batteries for this device, a battery pack or battery module can be used.

[0118] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use lithium-ion batteries as their power source.

[0119] Example

[0120] 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.

[0121] Example 1

[0122] Polycrystalline particles of the first positive electrode active material with a Dv50 of 13 μm, polycrystalline particles of the second positive electrode active material with a Dv50 of 9 μm, and single-crystal particles of the third positive electrode active material with a Dv50 of 3 μm were sequentially added to a 5 L stirred tank according to the following mass ratios: A, B, C = (A+B):C = 7:3 and A:B = 2.5:7.7. After mixing for 10 min, samples were taken to test the SPAN value, Dv99, CPD-1T, and BET specific surface area of ​​the mixture. All three types of positive electrode active material particles used have the chemical formula LiNi. 0.92 Co 0.06 Mn 0.02 O2.

[0123] Then, acetylene black (SP) as the conductive agent and polyvinylidene fluoride (PVDF) as the binder are added and premixed for 30 minutes. Finally, N-methylpyrrolidone (NMP) as the solvent is added and the mixture is rapidly stirred under vacuum to form a slurry. The mass ratio of the positive electrode active material mixture to acetylene black to PVDF is 96:2:2, and the solid content of the slurry is 70% by weight. The slurry is uniformly coated on both sides of an aluminum foil with a thickness of 12 μm. The coated electrode is then dried in an oven at 100-130℃ for half an hour. The positive electrode active material loading of the electrode is 21.5 mg / cm³. 2 The positive electrode sheet was taken out and cold-pressed by rollers. The compaction density, elongation in the length direction, pore volume, and shear stress were measured.

[0124] Figure 1 A scanning electron microscope (SEM) image of the positive electrode sheet of Example 1 is shown. The image clearly shows that the positive electrode active material particles have three different sizes, and the smaller particles fully fill the gaps between the larger particles.

[0125] Comparative Example 1

[0126] Polycrystalline particles of the first positive electrode active material with a Dv50 of 11 μm, polycrystalline particles of the second positive electrode active material with a Dv50 of 6.5 μm, and single-crystal particles of the third positive electrode active material with a Dv50 of 4.5 μm were sequentially added to a 5 L stirred tank in a mass ratio of (A+B):C = 3:7. After mixing for 10 min, samples were taken to test the SPAN value, Dv99, CPD-1T, and BET specific surface area of ​​the mixture. All three types of positive electrode active material particles used have the chemical formula LiNi. 0.92 Co 0.06 Mn 0.02 O2.

[0127] Then, acetylene black (SP) as the conductive agent and polyvinylidene fluoride (PVDF) as the binder are added and premixed for 30 minutes. Finally, N-methylpyrrolidone (NMP) as the solvent is added and the mixture is rapidly stirred under vacuum to form a slurry. The mass ratio of the positive electrode active material mixture to acetylene black to PVDF is 96:2:2, and the solid content of the slurry is 70% by weight. The slurry is uniformly coated on both sides of an aluminum foil with a thickness of 12 μm. The coated electrode is then dried in an oven at 100-130℃ for half an hour. The positive electrode active material loading of the electrode is 21.5 mg / cm³. 2 The positive electrode sheet was taken out and cold-pressed by rollers to obtain data on compaction density and elongation in the length direction.

[0128] Examples 2 to 12 and Comparative Examples 2 to 4

[0129] As shown in Table 1, the size and amount of the first positive electrode active material polycrystalline particles, the second positive electrode active material polycrystalline particles, and the third positive electrode active material single crystal particles were changed respectively to prepare positive electrode sheets in the same manner as in Example 1 and then tested.

[0130] Test method:

[0131] 1. Particle size and number of positive electrode active materials

[0132] Ten regions were randomly selected on the positive electrode sheet, and scanning electron microscope (SEM) images of each region were obtained using a ZEISS Sigma 300 microscope, referring to JY / T010-1996. In the SEM images, the distance between the two furthest points on the particle was measured as the particle size.

[0133] The particle size is used to determine which type of positive electrode active material the particles in the SEM images belong to. The number of each type of particle in each test area is counted from the SEM images, and the average number of each particle in each test area is calculated as the number of positive electrode active material particles, thereby calculating the ratio (a+b):c.

[0134] 2. Compacted density

[0135] The compaction density PD of the positive electrode sheet is calculated using the formula PD = M / (d × A). In the formula, M is the mass of a small circular piece with a diameter of 40 mm cut from the positive electrode sheet, which is the average value obtained by weighing 10 times; d is the thickness of the positive electrode sheet, which is the average value obtained by measuring the thickness 10 times; and A is the area of ​​the small circular piece with a diameter of 40 mm.

[0136] 3. Elongation in the length direction

[0137] The elongation in the length direction of the electrode after cold pressing is calculated using the formula ΔEL% = (L2 - L1) / L1 × 100%. In this formula, L1 is the distance between the marks before cold pressing, which is 1000 mm, and L2 is the distance between the marks after cold pressing. The marks are formed as follows: In the central region of the electrode, three line segments extending 1000 mm in length are taken at different positions along the width direction of the electrode, and the two endpoints of each line segment are marked. L2 is recorded as the average of the measured distances between the two endpoints of each line segment after cold pressing.

[0138] 4. Pore volume

[0139] Referring to GB / T 21650.2-2008 / ISO 15901-2:2006 "Determination of Pore Size Distribution and Porosity of Solid Materials by Mercury Intrusion Porosimetry and Gas Adsorption Method", Part II: Analysis of Mesopores and Macropores by Gas Adsorption Method, the determination was performed using an AccuPycⅡ1340 true density meter.

[0140] 5. Shear stress

[0141] Take the electrode to be tested and cut a sample with a width of 0.02m and a length of 0.1m. The edge of the sample has an exposed current collector area for welding the electrode tab. Attach a double-sided tape with a width of 0.02m and a length of 0.09m to a steel plate with a width of 0.02m and a length of 0.2m, with one end of the double-sided tape flush with one end of the steel plate. Attach the electrode sample to the double-sided tape, with one end of the sample flush with one end of the tape. Fix a paper strip with a width of 0.02m and a length of 0.15m to the exposed current collector surface of the electrode sample. Fix the end of the steel plate without the electrode attached using the lower clamp of the tensile testing machine. Fold the paper strip upwards and fix it with the upper clamp. Turn on the tensile testing machine and perform a continuous 180° stretch at a tensile speed of 0.05m / min. Record the maximum load displayed by the tensile testing machine when the electrode breaks, which is recorded as the shear stress of the electrode.

[0142] 6. Particle volume distribution: Particle size Dv10, Dv50, Dv90, Dv99

[0143] Particle size distribution was determined using laser diffraction method according to GB / T 19077-2016 / ISO 13320:2009, and the equipment was Malvern 3000.

[0144] 7.CPD-1T

[0145] Referring to GB / T 5162-2006 "Graphite Anode Materials for Lithium-ion Batteries", the test was conducted using a UTM7305 electronic pressure testing machine.

[0146] 8. BET specific surface area

[0147] The determination was performed using the TriStar II 3020 instrument, in accordance with GB / T 19587-2017 "Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method".

[0148] 9. TPD

[0149] The tap density was determined using a Dandong Baite BT-300 tap density meter, in accordance with GB / T 24533-2009 "Determination of tap density of metal powder".

[0150] The measurement results of each parameter in Examples 1 to 12 and Comparative Examples 1 to 4 are shown in Table 1 below.

[0151]

[0152] Based on the above results, it can be seen that Examples 1-12 all achieved high compaction density at an electrode length elongation of less than 0.8%, resulting in a compaction density that can generally exceed 3.6 g / cm³. 3 .

[0153] In contrast, Comparative Example 2 used only two types of positive electrode active material particles, and although it achieved 3.62 g / cm³... 3 The compaction density was achieved, but the electrode elongation in the length direction reached as high as 0.85%. Comparative Examples 1, 3, and 4 also used a mixture of two types of large-diameter polycrystalline particles and one type of small-diameter single-crystal particle, but the Dv50 values ​​of each particle did not fall within the range specified in this application. Therefore, the electrode elongation in the length direction at high compaction density was all higher than 0.8%. Even though the (A+B):C values ​​of Comparative Examples 3 and 4 fell within the range specified in this application, they still failed to achieve an electrode elongation in the length direction higher than 3.6 g / cm³ at a length below 0.8%. 3 The compaction density.

[0154] 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 sheet for a lithium-ion battery, characterized in that, The device includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer comprising a mixture of positive electrode active materials composed of: The first positive electrode active material polycrystalline particles have a particle size of 11.0~20.0μm, and the Dv50 of the first positive electrode active material polycrystalline particles is 12~16μm; Polycrystalline particles of a second positive electrode active material with a particle size of 6.0~10.5μm, wherein the Dv50 of the polycrystalline particles of the second positive electrode active material is 8~10μm; and The third cathode active material single crystal particles have a particle size of 1.1~5.2μm, and the Dv50 of the third cathode active material single crystal particles is 2.5~4μm. Wherein, the number of polycrystalline particles of the first positive electrode active material is a, the number of polycrystalline particles of the second positive electrode active material is b, and the number of single crystal particles of the third positive electrode active material is c, and (a+b):c is in the range of 5.7:4.3 to 7.7:2.

3.

2. The positive electrode sheet according to claim 1, characterized in that, (a+b):c is in the range of 6.1:3.9 to 7.2:2.

8.

3. The positive electrode sheet according to claim 1 or 2, characterized in that, The ratio of a:b is 1:9 to 7.5:2.

5.

4. The positive electrode sheet according to claim 1 or 2, characterized in that, The first positive electrode active material polycrystalline particles, the second positive electrode active material polycrystalline particles, and the third positive electrode active material single crystal particles are all ternary positive electrode active materials.

5. The positive electrode sheet according to claim 1 or 2, characterized in that, The first polycrystalline positive electrode material particles, the second polycrystalline positive electrode material particles, and the third single-crystal positive electrode material particles have the same or different chemical compositions, and all have the chemical formula LiNi. a Co b M (1-a-b) O2, where: 0.8≤a<1.0, 0<b<0.2, and a+b<1.0, and M is selected from one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, and Nb.

6. The positive electrode sheet according to claim 1 or 2, characterized in that, The first positive electrode active material polycrystalline particles, the second positive electrode active material polycrystalline particles, and the third positive electrode active material single crystal particles each independently include at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium iron phosphate and carbon composite material, lithium manganese phosphate, lithium manganese phosphate and carbon composite material, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composite material.

7. The positive electrode sheet according to claim 1 or 2, characterized in that, The pore volume of the positive electrode film is 1.2 mm. 3 / g~4.0mm 3 Within the range of / g.

8. The positive electrode sheet according to claim 7, characterized in that, The pore volume of the positive electrode film is 1.2 mm. 3 / g~2.0mm 3 Within the range of / g.

9. The positive electrode sheet according to claim 1 or 2, characterized in that, The shear stress of the positive electrode sheet is in the range of 0.65MPa to 0.85MPa.

10. The positive electrode sheet according to claim 1 or 2, characterized in that, In the positive electrode active material mixture, the total mass of the first positive electrode active material polycrystalline particles is A; the total mass of the second positive electrode active material polycrystalline particles is B; the total mass of the third positive electrode active material single crystal particles is C; and (A+B):C is in the range of 6:4 to 8:

2.

11. The positive electrode sheet according to claim 10, characterized in that, The ratio of (A+B):C is in the range of 6.5:3.5 to 7.5:2.

5.

12. The positive electrode sheet according to claim 10, characterized in that, The ratio of A to B is 2:8 to 7:

3.

13. The positive electrode sheet according to claim 1 or 2, characterized in that, The compaction density (CPD-1T) of the positive electrode active material mixture under 1 ton of pressure is 3.0 g / cm³. 3 ~3.2g / cm 3 Within the range.

14. The positive electrode sheet according to claim 13, characterized in that, The compaction density (CPD-1T) of the positive electrode active material mixture under 1 ton of pressure is 3.1 g / cm³. 3 ~3.2g / cm 3 Within the range.

15. The positive electrode sheet according to claim 1 or 2, characterized in that, The BET specific surface area of ​​the positive electrode active material mixture is 0.5 m². 2 / g~0.7m 2 Within the range of / g.

16. The positive electrode sheet according to claim 1 or 2, characterized in that, The SPAN value of the positive electrode active material mixture is in the range of 1.70 to 2.20, where SPAN = (Dv90 - Dv10) / Dv50.

17. The positive electrode sheet according to claim 16, characterized in that, The SPAN value of the positive electrode active material mixture is in the range of 1.75 to 2.

10.

18. The positive electrode sheet according to claim 1 or 2, characterized in that, The Dv99 of the positive electrode active material mixture is in the range of 18μm to 21μm.

19. The positive electrode sheet according to claim 18, characterized in that, The Dv99 of the positive electrode active material mixture is in the range of 19.5 μm to 21 μm.

20. The positive electrode sheet according to claim 1 or 2, characterized in that, The SPAN value of the first positive electrode active material polycrystalline particles satisfies SPAN≤1.20, where SPAN=(Dv90-Dv10) / Dv50.

21. The positive electrode sheet according to claim 20, characterized in that, The SPAN value of the first positive electrode active material polycrystalline particles satisfies 0.50≤SPAN≤1.

00.

22. The positive electrode sheet according to claim 1 or 2, characterized in that, The SPAN value of the second positive electrode active material polycrystalline particles satisfies SPAN≥1.20, where SPAN=(Dv90-Dv10) / Dv50.

23. The positive electrode sheet according to claim 22, characterized in that, The SPAN value of the second positive electrode active material polycrystalline particles satisfies 1.30≤SPAN≤1.

50.

24. The positive electrode sheet according to claim 1 or 2, characterized in that, The SPAN value of the single crystal particles of the third positive electrode active material satisfies SPAN≤1.70, where SPAN=(Dv90-Dv10) / Dv50.

25. The positive electrode sheet according to claim 24, characterized in that, The SPAN value of the single crystal particles of the third positive electrode active material satisfies 1.10≤SPAN≤1.

40.

26. The positive electrode sheet according to claim 1 or 2, characterized in that, The tap density (TPD) of the single crystal particles of the third positive electrode active material is ≤1.8 g / cm³. 3 .

27. The positive electrode sheet according to claim 26, characterized in that, The tap density (TPD) of the single crystal particles of the third positive electrode active material satisfies 1.2 g / cm³. 3 ≤TPD≤1.5g / cm 3 .

28. A lithium-ion battery, characterized in that, Includes the positive electrode sheet according to any one of claims 1 to 27.

29. A battery module, characterized in that, Including the lithium-ion battery as described in claim 28.

30. A battery pack, characterized in that, Includes the battery module as described in claim 29.

31. An electrical device, characterized in that, It includes at least one selected from the lithium-ion battery of claim 28, the battery module of claim 29, or the battery pack of claim 30.

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