Lithium-rich manganese-based positive electrode material and preparation method therefor, positive electrode sheet, lithium-ion battery and electric device

Abstract

The present application relates to a lithium-rich manganese-based positive electrode material, a positive electrode sheet, a lithium-ion battery and an electric device. The lithium-rich manganese-based positive electrode material has a particle size span (SPAN) of 1.6-2.0, a volume distribution particle size Dv50 of 6.5 μm-10.19 μm, a compaction density (CPD) of 2.9 g / cm3 to 3.3 g / cm3, and a BET specific surface area of 1.5 m2 / g to 3.5 m2 / g. By respectively adjusting and controlling the particle size span (SPAN), the volume distribution particle size Dv50, the compaction density (CPD) and the BET specific surface area of the lithium-rich manganese-based positive electrode material to be within the above ranges, the present application is beneficial to obtaining a higher compaction density of the positive electrode sheet under a high load; in addition, the positive electrode sheet has a relatively low elongation rate and has great processability.

Description

Lithium-rich manganese-based positive electrode material, preparation method thereof, positive electrode sheet, lithium ion battery and electric device

[0001] The present application claims priority to the Chinese patent application No. 202411123853.4, filed on August 15, 2024, and entitled "Lithium-rich manganese-based positive electrode material, preparation method thereof, positive electrode sheet, lithium ion battery and electric device", the content of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of lithium ion batteries, in particular to a lithium-rich manganese-based positive electrode material, a preparation method thereof, a positive electrode sheet, a lithium ion battery and an electric device. BACKGROUND

[0003] In recent years, lithium ion batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. due to their outstanding characteristics such as light weight, no pollution, no memory effect, etc. With the rapid expansion of the lithium ion battery market, high energy density has become the focus of attention, and thus higher requirements are put forward for the compaction density of the positive electrode sheet.

[0004] Lithium-rich manganese-based active materials have high specific capacity and energy density, and are considered as one of the most potential next-generation high-performance positive electrode materials. However, the compaction density of the positive electrode sheet using lithium-rich manganese-based active materials is low, which cannot meet the demand for high compaction density of the electrode sheet. SUMMARY

[0005] The present application provides a lithium-rich manganese-based positive electrode material, a preparation method thereof, a positive electrode sheet, a lithium ion battery and an electric device to improve the compaction density of the positive electrode sheet and the cycle performance of the lithium ion battery.

[0006] To achieve the above-mentioned purpose, the first aspect of the present application provides a lithium-rich manganese-based positive electrode material, wherein the particle size span SPAN of the lithium-rich manganese-based positive electrode material is 1.6-2.0, the volume distribution particle size Dv50 is 6.5 μm-10.1 μm, the compaction density CPD is 2.9 g / cm 3 -3.3 g / cm 3 , the specific surface area BET is 1.5 m 2 / g-3.5 m 2 / g.

[0007] Therefore, by regulating the volume distribution particle size Dv50 of the lithium-rich manganese-based positive electrode material in the above range, it is beneficial to avoid particle cracking and affect performance due to excessively large particles, and it is also beneficial to avoid difficulty in playing a main frame role due to excessively small particles; by regulating the particle size span SPAN of the lithium-rich manganese-based positive electrode material in the above range, it is beneficial to obtain higher compaction density of the material under high load; by regulating the compaction density CPD of the lithium-rich manganese-based positive electrode material in the above range, it is beneficial to improve the powder density of the material and improve the compression resistance of the pole piece; by regulating the specific surface area BET of the lithium-rich manganese-based positive electrode material in the above range, it is beneficial to avoid excessively large specific surface area and excessively large surface energy, affecting the processing performance. Therefore, by regulating the particle size span SPAN, the volume distribution particle size Dv50, the compaction density CPD and the specific surface area BET of the lithium-rich manganese-based positive electrode material in the above ranges, respectively, it is beneficial to obtain higher compaction density of the positive electrode pole piece under high load, and the positive electrode pole piece has lower elongation and excellent processing performance.

[0008] In some embodiments of the present application, the lithium-rich manganese-based positive electrode material comprises a first active material and a second active material, and the volume distribution particle sizes of the first active material and the second active material are different. Therefore, the use of two active materials with different volume distribution particle sizes can sufficiently improve the pore and volume utilization rate between particles and improve the compression resistance and ductility of the mixed positive electrode material.

[0009] In some embodiments of the present application, the volume distribution particle size Dv50 of the first active material is 6-10 μm, and the volume distribution particle size Dv50 of the second active material is 1.5-3.5 μm. Therefore, when the first active material and the second active material are used together, the first active material can play a frame role, and the second active material can play a filling role to improve the space utilization rate.

[0010] In some embodiments of the present application, the first active material is a polycrystalline lithium-rich manganese-based positive electrode material, and the second active material is one or more of a single-crystal lithium-rich manganese-based positive electrode material, a polycrystalline lithium-rich manganese-based positive electrode material and a lithium-nickel-based composite oxide.

[0011] In some embodiments of the present application, the first active material is a polycrystalline lithium-rich manganese-based positive electrode material, and the second active material is a single-crystal lithium-rich manganese-based positive electrode material. Therefore, when the first active material is a polycrystalline particle, it can play a large particle frame role, and when the second active material is a single-crystal particle, it can play a small particle filling role, improving the particle close-packing effect of the mixed powder as a whole.

[0012] In some embodiments of the present application, the mass ratio of the first active material and the second active material is (1.5-9):1. Thereby, both the material capacity is exerted, and the electrode sheet compaction density and the resistance to electrode sheet breakage caused by particle slip / displacement are considered.

[0013] In some embodiments of the present application, the volume distribution particle size Dv10 of the first active material is 0.5-2.5 μm.

[0014] In some embodiments of the present application, the volume distribution particle size Dv99 of the first active material is 7-20 μm.

[0015] When the volume distribution particle size Dv10 and the volume distribution particle size Dv99 of the first active material are in the above ranges respectively, the first active material plays both the frame role and the filling role.

[0016] In some embodiments of the present application, the volume distribution particle size Dv10 of the second active material is 0.5-2.5 μm.

[0017] In some embodiments of the present application, the volume distribution particle size Dv99 of the second active material is 1-7.5 μm.

[0018] When the volume distribution particle size Dv10 and the volume distribution particle size Dv99 of the second active material are in the above ranges respectively, the second active material plays the filling role further.

[0019] In some embodiments of the present application, the particle size span SPAN of the first active material is 0.5-1.2. Thereby, sufficient filling space and capacity exertion are provided for the positive electrode sheet.

[0020] In some embodiments of the present application, the particle size span SPAN of the first active material is 0.8-1.1.

[0021] In some embodiments of the present application, the particle size span SPAN of the second active material is 1.0-1.8. Thereby, the pores and spaces left by the first active material can be better filled, and the compaction density is improved.

[0022] In some embodiments of the present application, the particle size span SPAN of the second active material is 1.2-1.6.

[0023] In some embodiments of the present application, the specific surface area BET of the first active material is 1.3 m 2 / g-1.7 m 2 / g.

[0024] In some embodiments of the present application, the specific surface area BET of the second active material is 1.5 m 2 / g-2.1 m 2 / g.

[0025] When the specific surface area BET of the first active material and the second active material respectively falls within the above range, the lithium-rich manganese-based positive electrode material has more excellent electrochemical stability.

[0026] In some embodiments of the present application, the tap density TD of the first active material is 2.7 g / cm 3 -3.1 g / cm 3 .

[0027] In some embodiments of the present application, the tap density TD of the second active material is 2.5 g / cm 3 -2.8 g / cm 3 .

[0028] When the tap density PD of the first active material and the second active material respectively falls within the above range, the tap density of the pole piece using the lithium-rich manganese-based positive electrode material is improved.

[0029] In some embodiments of the present application, the true density of the first active material is 4.2 g / cm 3 -4.45 g / cm 3 .

[0030] In some embodiments of the present application, the true density of the second active material is 4.1 g / cm 3 -4.35 g / cm 3 .

[0031] When the true density of the first active material and the second active material respectively falls within the above range, the tap density of the pole piece using the lithium-rich manganese-based positive electrode material is improved.

[0032] In some embodiments of the present application, the tap density TD of the first active material is 1.8 g / cm 3 . Thus, the overall dispersibility of the lithium-rich manganese-based positive electrode material is improved, thereby improving the tap density and ductility of the positive electrode pole piece.

[0033] In some embodiments of the present application, the tap density TD of the first active material is 1.8 g / cm 3 -2.35 g / cm 3 .

[0034] In some embodiments of the present application, the tap density TD of the first active material is 2.0 g / cm 3 -2.35 g / cm 3.

[0035] In some embodiments of the present application, the tap density TD of the second active material is ≥ 1.8 g / cm3 3 Thus, it is beneficial to improve the overall dispersibility of the lithium-rich manganese-based positive electrode material, thereby improving the compaction density and ductility of the positive electrode sheet.

[0036] In some embodiments of the present application, the tap density TD of the second active material is 1.8 g / cm3 3 - 2.35 g / cm3 3 .

[0037] In some embodiments of the present application, the tap density TD of the second active material is 2.0 g / cm3 3 - 2.35 g / cm3 3 .

[0038] In some embodiments of the present application, the chemical formula of the first active material is Li[Li x Ni a Co b Mn c M d ]O 2-e Z e , wherein x+a+b+c+d=1, x>0, a+b+c+d<1, 0

[0039] In some embodiments of the present application, a>0.1, c≥0.5, d≥0.

[0040] In some embodiments of the present application, the chemical formula of the second active material is Li[Li x1 Ni a1 Co b1 Mn c1 M1 d1 ]O 2-e1 Z1 e1 , wherein x1+a1+b1+c1+d1=1, x1>0, a1+b1+c1+d1<1, 0

[0041] In some embodiments of the present application, a1>0.1, c1≥0.5, d1≥0.

[0042] In some embodiments of the present application, the lithium nickel-based composite oxide is a lithium-containing nickel-cobalt-manganese metal oxide.

[0043] In some embodiments of the present application, the lithium nickel-based composite oxide further comprises one or more of cobalt element, manganese element and aluminum element, and the molar proportion of the nickel element in all metal elements except the lithium element is ≥80%.

[0044] The second aspect of the present application provides a preparation method of a lithium-rich manganese-based positive electrode material, comprising the following steps:

[0045] mixing the first active material and the second active material to prepare the lithium-rich manganese-based positive electrode material; wherein the volume distribution particle size of the first active material and the second active material is different;

[0046] The particle size span SPAN of the lithium-rich manganese-based positive electrode material is 1.6-2.0, the volume distribution particle size Dv50 is 6.5 μm-10.1 μm, the compacted density CPD is 2.9 g / cm 3 -3.3 g / cm 3 , the specific surface area BET is 1.5 m 2 / g-3.5 m 2 / g.

[0047] The third aspect of the present application provides a positive electrode sheet comprising the lithium-rich manganese-based positive electrode material of the first aspect of the present application.

[0048] The positive electrode sheet of the present application comprises the lithium-rich manganese-based positive electrode material provided by the present application, and has a high compacted density and a low ductility.

[0049] In some embodiments of the present application, the compacted density of the positive electrode sheet is ≥2.86 g / cm 3 .

[0050] In some embodiments of the present application, the compacted density of the positive electrode sheet is 2.86 g / cm 3 -3.1 g / cm 3 .

[0051] In some embodiments of the present application, the ductility of the positive electrode sheet is ≤0.7%.

[0052] In some embodiments of the present application, the ductility of the positive electrode sheet is 0.43%-0.7%.

[0053] The fourth aspect of the present application provides a lithium ion battery comprising the positive electrode sheet of the third aspect of the present application.

[0054] The lithium ion battery of the present application comprises the lithium-rich manganese-based positive electrode material provided by the present application, has a high energy density and capacity, and excellent cycle performance.

[0055] The fifth aspect of the present application provides a power-using device comprising at least one of the positive electrode sheet of the third aspect of the present application and the lithium ion battery of the fourth aspect of the present application.

[0056] The power-using device of the present application comprises the lithium ion battery provided by the present application, and thus has at least the same advantages as the lithium ion battery.

[0057] The details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present application will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF DRAWINGS

[0058] For better describing and illustrating the embodiments or examples provided by the present application, one or more drawings can be referred to. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any one of the disclosed applications, the presently described embodiments or examples, and the best mode presently contemplated of these applications. Moreover, the same reference numbers are used throughout the drawings to represent the same components. In the drawings:

[0059] FIG. 1 is a schematic view of a battery cell according to an embodiment of the present application.

[0060] FIG. 2 is an exploded view of the battery cell shown in FIG. 1 according to an embodiment of the present application.

[0061] FIG. 3 is a schematic view of a battery module according to an embodiment of the present application.

[0062] FIG. 4 is a schematic view of a battery pack according to an embodiment of the present application.

[0063] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.

[0064] FIG. 6 is a schematic view of a power-using device using the lithium ion battery according to an embodiment of the present application as a power source.

[0065] BRIEF DESCRIPTION OF DRAWINGS 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 housing; 52 electrode assembly; 53 cover plate; 6 power-using device. DETAILED DESCRIPTION

[0066] Hereinafter, some embodiments of the lithium-rich manganese-based positive electrode material, the positive electrode sheet, the secondary battery, and the power-using device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed explanations are omitted. For example, there are cases where detailed explanations of matters known well, repeated explanations of substantially identical structures are 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 so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0067] The "ranges" disclosed in the present application can be defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The ranges defined in this way can be inclusive or exclusive of the end values, either end value can be included or excluded independently, and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are also listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise specified, the numerical range "j-k" represents a shorthand notation for any integer combination of real numbers between j and k, where j and k are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein, and "0-5" is just a shorthand notation for these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥ 2, it is equivalent to listing the parameter as, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when it is stated that a certain parameter is an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0068] In the present application, "a plurality of", "a plurality of kinds", and the like, unless otherwise specified, mean greater than or equal to 2 in number. For example, "one or more" means one or more than or equal to two.

[0069] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0070] Reference to an "embodiment" in this document means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment or implementation of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is expressly understood that the embodiments described herein are merely examples from a potentially infinite number of embodiments that serve the same or similar purpose or functions. It is expressly understood that all functionally or structurally equivalent steps, processes, compositions, means, components, and the like are within the scope of the application.

[0071] Those skilled in the art can understand that, in the method of each embodiment or embodiment, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. If not specifically stated, all steps of the application can be performed in sequence or randomly, preferably in sequence.

[0072] In this application, the open technical features or technical solutions described with the words "containing", "including", "comprising" and the like do not exclude additional members other than the listed members, and can be regarded as providing both the closed features or solutions composed of the listed members and the open features or solutions including additional members outside the listed members. In this application, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0073] In this application, "optionally", "optional" and "optional" mean optional, that is, selected from either of the two parallel solutions "have" or "have". If there are multiple "options" in a technical solution, if there is no special statement and no contradictory relationship or mutual restriction, each "option" is independent.

[0074] The lithium-rich manganese-based active material has high specific capacity and energy density, and is considered one of the most potential next-generation high-performance positive electrode materials. However, the lithium-rich manganese-based active material has a certain gap in true density and sphericity compared with conventional ternary positive electrode materials, resulting in difficulty in improving the positive electrode sheet compaction density in the actual processing process. The inventors found that the means to solve the compaction density of the electrode sheet is usually to mix large and small particles, and to pull the difference between the volume average particle size Dv50 of the large particles and the small particles, so as to achieve better particle mixing. However, since the particles in the electrode sheet are in a mixed state of large and small particles, it is not only the particle properties of large and small particles alone, so if only the volume average particle size Dv50 of the large and small particles is limited, the improvement degree of the electrode sheet compaction density is limited, so if the electrode sheet compaction density is to be improved, the related parameters of the mixed powder need to be considered.

[0075] Based on the above problems, the particle size span SPAN, the volume distribution particle size Dv50, the compaction density CPD and the specific surface area BET of the lithium-rich manganese-based positive electrode material are regulated to improve the compaction density of the positive electrode sheet.

[0076] One or more embodiments of the present application provide a lithium-rich manganese-based positive electrode material, wherein the particle size span SPAN of the lithium-rich manganese-based positive electrode material is 1.6-2.0, the volume distribution particle size Dv50 is 6.5 μm-10.1 μm, the compaction density CPD is 2.9 g / cm 3 -3.3 g / cm 3 , and the specific surface area BET is 1.5 m 2 / g-3.5 m 2 / g.

[0077] Understandably, by regulating the volume distribution particle size Dv50 of the lithium-rich manganese-based positive electrode material in the above range, it is beneficial to avoid the cracking of particles due to the too large particle size, and it is also beneficial to avoid the difficulty of playing a main role due to the too small particle size. By regulating the particle size span SPAN of the lithium-rich manganese-based positive electrode material in the above range, it is beneficial to obtain a higher compaction density of the material under high load. By regulating the compaction density CPD of the lithium-rich manganese-based positive electrode material in the above range, it is beneficial to improve the powder density of the material and improve the compression resistance of the electrode sheet. By regulating the specific surface area BET of the lithium-rich manganese-based positive electrode material in the above range, it is beneficial to avoid the too large surface energy caused by the too large specific surface area, which affects the processing performance. Therefore, by regulating the particle size span SPAN, the volume distribution particle size Dv50, the compaction density CPD and the specific surface area BET of the lithium-rich manganese-based positive electrode material in the above ranges respectively, it is beneficial to obtain a higher compaction density of the positive electrode sheet under high load, and the positive electrode sheet has a lower elongation and excellent processing performance.

[0078] As a non-limiting example, the particle size span SPAN of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 1.6, 1.61, 1.62, 1.63, 1.64, 1.65, 1.67, 1.7, 1.73, 1.75, 1.78, 1.8, 1.83, 1.85, 1.88, 1.9, 1.93, 1.95, 1.97, 2.0 or a range between any two of the above values, etc.

[0079] It should be noted that the particle size span SPAN mentioned above = (Dv90-Dv10) / Dv50. Among them, Dv10 refers to the particle size corresponding to 10% in the volume distribution, Dv50 refers to the particle size corresponding to 50% in the volume distribution, and Dv90 refers to the particle size corresponding to 50% in the volume distribution; Referring to GB / T 19077-2016 / ISO 13320:2009 Particle Size Distribution Laser Diffraction Method, laser particle size analyzer is used to determine Dv10, Dv50 and Dv90, and then SPAN is calculated according to the formula (Dv90-Dv10) / Dv50.

[0080] As an example, the volume distribution particle size Dv50 of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 6.5 μm, 6.6 μm, 6.7 μm, 6.8 μm, 6.9 μm, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.7 μm, 7.8 μm, 7.9 μm, 8 μm, 8.1 μm, 8.2 μm, 8.3 μm, 8.4 μm, 8.5 μm, 8.6 μm, 8.7 μm, 8.8 μm, 8.9 μm, 9 μm, 9.1 μm, 9.2 μm, 9.3 μm, 9.4 μm, 9.5 μm, 9.6 μm, 9.7 μm, 9.8 μm, 9.9 μm, 10 μm, 10.1 μm, or a range between any two of the above values.

[0081] It should be noted that the volume distribution particle size Dv50 mentioned above refers to the particle size corresponding to 50% in the volume distribution; It can be determined by referring to GB / T 19077-2016 / ISO 13320:2009 Particle Size Distribution Laser Diffraction Method.

[0082] As a non-limiting example, the compaction density CPD of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 2.9 g / cm 3 , 2.93 g / cm 3 , 2.95 g / cm 3 , 2.98 g / cm 3 , 3.0 g / cm 3 , 3.03 g / cm 3 , 3.05 g / cm 3 , 3.08 g / cm 3 , 3.1 g / cm 3 , 3.13 g / cm 3 , 3.15 g / cm 3 , 3.18 g / cm 3 , 3.2 g / cm 3 , 3.23 g / cm 3 , 3.25 g / cm3 3.28 g / cm3 3 3.3 g / cm3 3 or a range between any two of the above compaction densities, etc.

[0083] It should be noted that the compaction density CPD of the lithium-rich manganese-based positive electrode material mentioned above refers to the compaction density CPD-5T of the lithium-rich manganese-based positive electrode material under a pressure of 5 tons. As an example, reference can be made to GB / T 5162-2006 "Lithium Ion Battery Graphite Anode Material", and the UTM7305 electronic pressure testing machine is used for determination.

[0084] As a non-limiting example, the specific surface area BET of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 1.5 m2 / g, 1.6 m2 / g, 1.7 m2 / g, 1.8 m2 / g, 1.9 m2 / g, 2.0 m2 / g, 2.1 m2 / g, 2.2 m2 / g, 2.3 m2 / g, 2.4 m2 / g, 2.5 m2 / g, 2.6 m2 / g, 2.7 m2 / g, 2.8 m2 / g, 2.9 m2 / g, 3.0 m2 / g, 3.1 m2 / g, 3.2 m2 / g, 3.3 m2 / g, 3.4 m2 / g, 3.5 m2 / g, or a range between any two of the above specific surface areas, etc. 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 or a range between any two of the above specific surface areas, etc.

[0085] It should be noted that the specific surface area BET of the lithium-rich manganese-based positive electrode material mentioned above can be determined by reference to GB / T 19587-2004 Gas Adsorption BET Method.

[0086] In some embodiments, the lithium-rich manganese-based positive electrode material comprises a first active material and a second active material, and the first active material and the second active material have different volume distribution particle sizes. In this way, the use of two different volume distribution particle sizes of active materials can fully improve the utilization rate of inter-particle pores and volume, and improve the compression resistance and ductility of the mixed positive electrode material.

[0087] ​​​​​​​​​​​​​​​​​​​​The above-mentioned "first active material", "second active material" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implying the importance or quantity of the indicated technical features. Moreover, "first", "second" and the like only serve the purpose of non-exhaustive enumeration description and should be understood as not constituting a closed limitation on the quantity.

[0088] In some optional embodiments, the volume distribution particle size Dv50 of the first active material is 6-10 μm; for example, it can be but is not limited to 6 μm, 6.3 μm, 6.5 μm, 6.8 μm, 7 μm, 7.3 μm, 7.5 μm, 7.8 μm, 8 μm, 8.3 μm, 8.5 μm, 8.7 μm, 9 μm, 9.3 μm, 9.5 μm, 9.7 μm, 10 μm or a range between any two of the above values, etc. When the volume distribution particle size Dv50 of the first active material is in the above range, it is beneficial for the material capacity to play a role, and at the same time the material particles are not easy to break.

[0089] As a possible embodiment, the volume distribution particle size Dv50 of the second active material is 1.5-3.5 μm; for example, it can be but is not limited to 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm or a range between any two of the above values, etc.

[0090] When the first active material and the second active material with volume distribution particle size Dv50 in the above ranges are used together, the first active material can play a role of framework, and the second active material can play a role of filling to improve the space utilization.

[0091] It should be noted that the volume distribution particle size Dv50 of the first active material and the second active material mentioned above can be determined according to GB / T 19077-2016 / ISO 13320:2009 Particle Size Distribution Laser Diffraction Method.

[0092] In some embodiments, the first active material is a polycrystalline lithium-rich manganese-based positive electrode material, and the second active material is one or more of a single-crystal lithium-rich manganese-based positive electrode material, a polycrystalline lithium-rich manganese-based positive electrode material and a lithium-nickel-based composite oxide.

[0093] In some embodiments, the first active material is a polycrystalline lithium-rich manganese-based positive electrode material, and the second active material is a single-crystalline lithium-rich manganese-based positive electrode material. In this way, the first active material, when being polycrystalline particles, can play a large particle frame role, and the second active material, when being single-crystalline particles, can play a small particle filling role, thereby improving the particle close-packing effect of the mixed powder as a whole.

[0094] As a possible implementation, the mass ratio of the first active material to the second active material is (1.5-9):1; for example, it can be but is not limited to 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, or a range between any two of the above mass ratios. When the mass ratio of the first active material to the second active material is within the above range, both the material specific capacity and the electrode sheet compaction density can be taken into account, and the electrode sheet can resist the electrode sheet breakage caused by particle sliding / displacement.

[0095] In some optional embodiments, the volume distribution particle size Dv10 of the first active material is 0.5 μm-2.5 μm; for example, it can be but is not limited to 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, or a range between any two of the above values.

[0096] As a possible implementation, the volume distribution particle size Dv99 of the first active material is 7 μm-20 μm; for example, it can be but is not limited to 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, 20 μm, or a range between any two of the above values.

[0097] When the volume distribution particle size Dv10 and the volume distribution particle size Dv99 of the first active material are within the above ranges, respectively, the first active material can play both a frame role and a filling role.

[0098] In some optional embodiments, the second active material has a volume distribution particle size Dv10 of 0.5 μm to 2.5 μm; for example, but not limited to, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, or a range between any two of the foregoing values.

[0099] In some embodiments, the second active material has a volume distribution particle size Dv99 of 1 μm to 7.5 μm; for example, but not limited to, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, or a range between any two of the foregoing values.

[0100] When the volume distribution particle size Dv10 and the volume distribution particle size Dv99 of the second active material are within the above ranges, respectively, it is further beneficial for the second active material to play a filling role.

[0101] In some exemplary embodiments, the first active material has a particle size span SPAN of 0.5 to 1.2; for example, but not limited to, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, or a range between any two of the foregoing values. When the particle size span SPAN of the first active material is within the above range, it is beneficial to provide sufficient filling space and capacity for the positive electrode sheet.

[0102] In some optional embodiments, the particle size span SPAN of the first active material is 0.8 to 1.1.

[0103] As one possible embodiment, the particle size span SPAN of the second active material is 1.0 to 1.8; for example, but not limited to, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, or a range between any two of the foregoing values. When the particle size span SPAN of the second active material is within the above range, it can better fill the pores and spaces left by the first active material and improve the compaction density.

[0104] In some optional embodiments, the particle size span SPAN of the second active material is 1.2 to 1.6.

[0105] In some embodiments, the tap density TD of the first active material is ≥ 1.8 g / cm 3 When the tap density of the first active material is in the above range, it is beneficial to improve the overall dispersibility of the lithium-rich manganese-based positive electrode material, thereby improving the compaction density and ductility of the positive electrode sheet.

[0106] In some embodiments, the specific surface area BET of the first active material is 1.3 m 2 / g-1.7 m 2 / g; for example, but not limited to, 1.3 m 2 / g, 1.35 m 2 / g, 1.4 m 2 / g, 1.45 m 2 / g, 1.5 m 2 / g, 1.55 m 2 / g, 1.6 m 2 / g, 1.65 m 2 / g, 1.7 m 2 / g, or a range between any two of the above specific surface areas, etc.

[0107] In some embodiments, the specific surface area BET of the second active material is 1.5 m 2 / g-2.1 m 2 / g; for example, but not limited to, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g, 2.0 m 2 / g, 2.1 m 2 / g, or a range between any two of the above specific surface areas, etc.

[0108] When the specific surface areas of the first active material and the second active material are in the above ranges respectively, the lithium-rich manganese-based positive electrode material can have more excellent electrochemical stability.

[0109] In some embodiments, the compaction density PD of the first active material is 2.7 g / cm 3 -3.1 g / cm 3 ; for example, but not limited to, 2.7 g / cm 3 , 2.75 g / cm 3 , 2.8 g / cm 3 , 2.85 g / cm 3 , 2.9 g / cm 3 , 2.95 g / cm 3 , 3.0 g / cm 33.05 g / cm3 3 3.1 g / cm3 3 or a range between any two of the above compaction densities, etc.

[0110] In some embodiments, the second active material has a compaction density PD of 2.5 g / cm3 3 - 2.8 g / cm3 3 ; for example, but not limited to, 2.5 g / cm3 3 , 2.55 g / cm3 3 , 2.6 g / cm3 3 , 2.65 g / cm3 3 , 2.7 g / cm3 3 , 2.75 g / cm3 3 , 2.8 g / cm3 3 or a range between any two of the above compaction densities, etc.

[0111] When the first and second active materials have compaction densities PD in the above ranges, respectively, it is beneficial to improve the compaction density of the electrode sheet using the lithium-rich manganese-based positive electrode material.

[0112] In some embodiments, the first active material has a true density of 4.2 g / cm3 3 - 4.45 g / cm3 3 ; for example, but not limited to, 4.2 g / cm3 3 , 4.25 g / cm3 3 , 4.3 g / cm3 3 , 4.35 g / cm3 3 , 4.4 g / cm3 3 , 4.45 g / cm3 3 or a range between any two of the above true densities, etc.

[0113] In some embodiments, the second active material has a true density of 4.1 g / cm3 3 - 4.35 g / cm3 3 ; for example, but not limited to, 4.1 g / cm3 3 , 4.15 g / cm3 3 , 4.2 g / cm3 3 , 4.25 g / cm3 3 , 4.3 g / cm3 3 , 4.35 g / cm3 3 or a range between any two of the above true densities, etc.

[0114] When the first and second active materials have true densities in the above ranges, respectively, it is beneficial to improve the compaction density of the electrode sheet using the lithium-rich manganese-based positive electrode material.

[0115] In some alternative embodiments, the tap density TD of the first active material is 1.8 g / cm3 3 - 2.35 g / cm3 3 For example, but not limited to, 1.8 g / cm3 3 , 1.82 g / cm3 3 , 1.85 g / cm3 3 , 1.87 g / cm3 3 , 1.9 g / cm3 3 , 1.93 g / cm3 3 , 1.95 g / cm3 3 , 1.98 g / cm3 3 , 2.0 g / cm3 3 , 2.03 g / cm3 3 , 2.05 g / cm3 3 , 2.07 g / cm3 3 , 2.1 g / cm3 3 , 2.13 g / cm3 3 , 2.15 g / cm3 3 , 2.17 g / cm3 3 , 2.2 g / cm3 3 , 2.23 g / cm3 3 , 2.25 g / cm3 3 , 2.27 g / cm3 3 , 2.3 g / cm3 3 , 2.33 g / cm3 3 , 2.35 g / cm3 3 or a range between any two tap densities mentioned above.

[0116] As one possible embodiment, the tap density TD of the first active material is 2.0 g / cm3 3 - 2.35 g / cm3 3 .

[0117] In some embodiments, the tap density TD of the second active material is ≥ 1.8 g / cm3 3 When the tap density of the second active material is within the above range, it is beneficial to improve the overall dispersibility of the lithium-rich manganese-based positive electrode material, thereby improving the compaction density and ductility of the positive electrode sheet.

[0118] In some alternative embodiments, the tap density TD of the second active material is 1.8 g / cm3 3 - 2.35 g / cm3 3 For example, but not limited to, 1.8 g / cm3 3 , 1.82 g / cm3 3 , 1.85 g / cm3 3 , 1.87 g / cm33 1.9 g / cm3 3 1.93 g / cm3 3 1.95 g / cm3 3 1.98 g / cm3 3 2.0 g / cm3 3 2.03 g / cm3 3 2.05 g / cm3 3 2.07 g / cm3 3 2.1 g / cm3 3 2.13 g / cm3 3 2.15 g / cm3 3 2.17 g / cm3 3 2.2 g / cm3 3 2.23 g / cm3 3 2.25 g / cm3 3 2.27 g / cm3 3 2.3 g / cm3 3 2.33 g / cm3 3 2.35 g / cm3 3 or a range between any two of the above tap densities.

[0119] As one possible implementation, the second active material has a tap density TD of 2.0 g / cm3 3 - 2.35 g / cm3 3 .

[0120] As one possible implementation, the first active material has a chemical formula of Li[Li x Ni a Co b Mn c M d ]O 2-e Z e where x + a + b + c + d = 1, x > 0, a + b + c + d < 1, 0 < b < 0.1, 0 < e < 0.2, M elements include one or more of Te, Se, Mg, Nb, Cr, Ce, Fe, Ta, B, V, Ti, Sn, W, and Mo, and Z elements include one or more of F, Cl, and Br.

[0121] In some alternative implementations, a > 0.1, c > 0.5, and d > 0.

[0122] As one possible implementation, the second active material has a chemical formula of Li[Li a1 Ni b1 Co c1 Mn d1 M1 2-e1 ]O2-e1 Z1 e1 wherein x1+a1+b1+c1+d1=1, x1>0, a1+b1+c1+d1<1, 0<b1≤0.1, 0≤e≤0.2, M1 elements include one or more of Te, Se, Mg, Nb, Cr, Ce, Fe, Ta, B, V, Ti, Sn, W and Mo, and Z1 elements include one or more of F, Cl and Br.

[0123] It should be noted that when x1=0, the second active material is a ternary positive electrode material.

[0124] In some alternative embodiments, a1>0.1, c1≥0.5, and d1≥0.

[0125] In some exemplary embodiments, the lithium nickel-based composite oxide is a lithium-containing nickel-cobalt-manganese metal oxide.

[0126] In some of the embodiments, the lithium nickel-based composite oxide further comprises one or more of cobalt elements, manganese elements and aluminum elements, and the molar proportion of the nickel element in all metal elements except the lithium element is ≥80%.

[0127] One or more embodiments of the present application provide a preparation method of a lithium-rich manganese-based positive electrode material, which can be used to prepare the lithium-rich manganese-based positive electrode material described above. The preparation method comprises the following steps:

[0128] mixing the first active material and the second active material to prepare the lithium-rich manganese-based positive electrode material; wherein the volume distribution particle sizes of the first active material and the second active material are different; the particle size span SPAN of the lithium-rich manganese-based positive electrode material is 1.6-2.0, the volume distribution particle size Dv50 is 6.5 μm-10.1 μm, the compaction density CPD is 2.9 g / cm 3 -3.3 g / cm 3 , the specific surface area BET is 1.5 m 2 / g-3.5 m 2 / g.

[0129] In addition, the lithium ion battery and the electric device of the present application are described below with appropriate reference to the accompanying drawings.

[0130] Generally, the lithium ion battery comprises a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the charging and discharging process of the battery, active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly playing a role in preventing the short circuit of the positive and negative electrodes, while allowing ions to pass through.

[0131] Positive electrode sheet

[0132] The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, and the positive electrode active material layer includes the lithium-rich manganese-based positive electrode material described above.

[0133] In an embodiment, the positive electrode tab has a compaction density ≥ 2.86 g / cm 3 .

[0134] In some alternative embodiments, the positive electrode tab has a compaction density of 2.86 g / cm 3 - 3.1 g / cm 3 ; for example, but not limited to, 2.86 g / cm 3 , 2.88 g / cm 3 , 2.90 g / cm 3 , 2.92 g / cm 3 , 2.94 g / cm 3 , 2.96 g / cm 3 , 2.98 g / cm 3 , 3.0 g / cm 3 , 3.02 g / cm 3 , 3.04 g / cm 3 , 3.06 g / cm 3 , 3.08 g / cm 3 , 3.1 g / cm 3 , or a range between any two of the above compaction densities, etc.

[0135] It should be noted that the compaction density of the positive electrode tab mentioned above can be calculated by the formula PD = M / (d x A). In the formula, M is the mass of a 40 mm diameter small disc cut from the positive electrode tab, which is averaged by 10 times of weighing; d is the thickness of the positive electrode tab, which is averaged by 10 times of thickness measurement; and A is the area of the 40 mm diameter small disc.

[0136] In some embodiments, the positive electrode tab has an elongation ≤ 0.7%.

[0137] In some alternative embodiments, the positive electrode tab has an elongation of 0.43% - 0.7%; for example, but not limited to, 0.43%, 0.45%, 0.48%, 0.5%, 0.53%, 0.55%, 0.58%, 0.6%, 0.63%, 0.65%, 0.68%, 0.7%, or a range between any two of the above elongations, etc.

[0138] As an example, the elongation of the above-mentioned positive electrode sheet can be calculated by the formula ΔEL% = (L2-L1) / L1x100%. In the 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 by taking three 1000 mm long line segments extending in the length direction of the sheet at different positions in the width direction of the sheet in the center region of the sheet, and marking the two end points of the line segments. L2 is recorded as the average of the measured values of the distances between the two end points of each line segment after cold pressing.

[0139] In some embodiments, the lithium ion battery comprises the above-mentioned positive electrode sheet.

[0140] As a non-limiting example, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode active material layer is provided on either one or both of the two opposite surfaces of the positive electrode current collector.

[0141] In some of the embodiments, the positive electrode current collector can adopt a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be adopted. The composite current collector can comprise a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be obtained by forming a metal material on a polymer material base material. In the positive electrode current collector, non-limiting examples of the metal material can include one or more of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, a silver alloy, and the like. In the positive electrode current collector, non-limiting examples of the polymer material base material can include one or more of a polypropylene (PP) base material, a polyethylene terephthalate (PET) base material, a polybutylene terephthalate (PBT) base material, a polystyrene (PS) base material, a polyethylene (PE) base material, and the like.

[0142] It can be understood that the battery will be accompanied by lithium (Li) deintercalation and consumption during charging and discharging, and the content of Li in the positive electrode sheet is different when the battery is discharged to different states. In the enumeration of the positive electrode material in this application, the content of Li is the initial state of the material unless otherwise stated. After the positive electrode material is applied to the positive electrode sheet in the battery system, the content of Li in the positive electrode material contained in the sheet will usually change after charging and discharging cycles. Among them, the content of Li can be quantified by molar content, but is not limited thereto. As for "the content of Li is the initial state of the material", the initial state of the material refers to the state before the material is fed into the positive electrode slurry. It can be understood that new materials obtained by proper modification on the basis of the enumerated positive electrode materials are also within the scope of positive electrode materials, and the foregoing proper modification refers to acceptable modification methods for the positive electrode material, and non-limiting examples include coating modification.

[0143] In the enumeration of the positive electrode material in the present application, the content of oxygen (O) is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual content of O will appear to be floating. Among them, the content of O can be measured by molar content, but not limited to this.

[0144] In some embodiments, the positive electrode active material can also use the positive electrode active material for batteries known in the art. As a non-limiting example, the positive electrode active material can include one or more of the following materials: lithium-containing phosphates of olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used only one kind alone, or two or more can be used in combination. Among them, examples of lithium transition metal oxides can include, but are not limited to, one or more of lithium cobalt oxide (such as LiCoO2), 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, and modified compounds thereof. Non-limiting examples of lithium-containing phosphates of olivine structure can include, but are not limited to, one or more of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon. Non-limiting examples of lithium cobalt oxide can include LiCoO2; non-limiting examples of lithium nickel oxide can include LiNiO2; non-limiting examples of lithium manganese oxide can include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxide can include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to as NCM 811 ), etc. Non-limiting examples of lithium nickel cobalt aluminum oxide can include LiNi 0.80 Co 0.15 Al 0.05 O2.

[0145] In some embodiments, the positive electrode active material layer optionally further includes a binder. As non-limiting examples, the binder can include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0146] In some embodiments, the positive electrode active material layer optionally further includes a conductive agent. As non-limiting examples, the conductive agent can include one or more of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0147] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry on at least one side surface of the positive electrode current collector; and subjecting the positive electrode current collector to a drying, cold-pressing, or other process to obtain the positive electrode tab. The solvent can be selected from, but is not limited to, any of the above-mentioned embodiments, such as N-methyl pyrrolidone (NMP). The positive electrode slurry can be coated on a single surface of the positive electrode current collector or on both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40 wt% to 80 wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5,000 mPa·s to 25,000 mPa·s. When the positive electrode slurry is coated, the coating unit area density, in terms of dry weight (excluding the solvent), can be 15 mg / cm 2 - 35 mg / cm 2 . The positive electrode tab can have a compacted density of 3.0 g / cm 3 - 3.6 g / cm 3 , optionally 3.3 g / cm 3 - 3.5 g / cm 3 .

[0148] The negative electrode tab

[0149] The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material.

[0150] As non-limiting examples, the negative electrode current collector has two opposite surfaces in the thickness direction of the negative electrode current collector, and the negative electrode active material layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0151] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be obtained by forming a metal material on a polymer material base layer. Non-limiting examples of the metal material in the negative current collector can include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, and the like. Non-limiting examples of the polymer material base layer in the negative current collector can include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and the like.

[0152] In some embodiments, the negative active material can employ a negative active material for a battery known in the art. As non-limiting examples, the negative active material can include one or more of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, and the like. The silicon-based material can include one or more of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can include one or more of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery can also be used. The negative active material can be used alone or in combination of two or more.

[0153] In some embodiments, the negative active material layer can further optionally include a binder. The binder can include one or more 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).

[0154] In some embodiments, the negative active material layer can further optionally include a conductive agent. The conductive agent can include one or more of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0155] In some embodiments, the negative active material layer can further optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

[0156] In some embodiments, the negative electrode sheet can be prepared by dispersing the components described above for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (a non-limiting example of the solvent is deionized water), to form a negative electrode slurry; coating the negative electrode slurry on at least one side surface of the negative electrode current collector; and drying, cold-pressing, or the like, to obtain the negative electrode sheet. The surface of the negative electrode current collector to which the negative electrode slurry is coated can be a single surface of the negative electrode current collector, or both surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 40 wt% to 60 wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000 mPa s to 10000 mPa s. The coating unit area density of the negative electrode slurry, on a dry weight basis (excluding the solvent), can be 75 g / m 2 -220 g / m 2 . The compaction density of the negative electrode sheet can be 1.0 g / cm 3 -1.8 g / cm 3 .

[0157] Electrolyte

[0158] The electrolyte has a function of conducting ions between the positive electrode sheet and the negative electrode sheet. The type of the electrolyte is not particularly limited in the present application, and can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0159] In some embodiments, the electrolyte is an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0160] In some embodiments, the electrolyte salt can include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluoro-oxalato-borate (LiDFOB), lithium bis-oxalato-borate (LiBOB), lithium difluoro-bis-oxalato-phosphate (LiDFOP), and lithium tetrafluoro-oxalato-phosphate (LiTFOP).

[0161] In some embodiments, the solvent can include ethylene carbonate (EC, ), propylene carbonate (PC, ), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), and the like.

[0162] In some embodiments, the electrolyte solution further optionally includes an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can further include an additive that can improve certain performance of the battery, such as an additive that improves overcharge performance of the battery, an additive that improves high-temperature or low-temperature performance of the battery, and the like.

[0163] In some embodiments, the additive in the electrolyte solution can include, but is not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), and the like.

[0164] Separator film

[0165] In some embodiments, the lithium ion battery further includes a separator film. The type of the separator film is not particularly limited in the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0166] In some embodiments, the material of the separator film can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0167] In some embodiments, the thickness of the separator film is 6-40 pm, and can be 13 pm.

[0168] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be used to make an electrode assembly through a winding process or a stacking process.

[0169] In some embodiments, the lithium ion battery can include an outer package. The outer package can be used to package the electrode assembly and the electrolyte solution described above.

[0170] In some embodiments, the outer package of the lithium ion battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, and the like. The outer package of the lithium ion battery can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, and further, non-limiting examples of the plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate, and the like.

[0171] The lithium ion battery includes at least one battery cell. The lithium ion battery can include one or more battery cells.

[0172] In the present application, "battery cell" refers to a basic unit capable of converting chemical energy and electrical energy to each other, and further, generally includes at least a positive electrode sheet, a negative electrode sheet, and an electrolyte. In the process of charging and discharging the battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct active ions between the positive electrode sheet and the negative electrode sheet.

[0173] The shape of the battery cell is not particularly limited in the present application, and can be cylindrical, square, or any other shape. For example, FIG. 1 is a battery cell 5 of a square structure as an example.

[0174] In some embodiments, referring to FIG. 2, the outer package can include a housing 51 and a cover plate 53. The housing 51 can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be provided on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and a person skilled in the art can select according to actual needs.

[0175] The lithium ion battery can be a battery module 4 or a battery pack 1.

[0176] The battery module includes at least one battery cell. The number of battery cells contained in the battery module can be one or more, and a person skilled in the art can select a suitable number according to the application and capacity of the battery module.

[0177] FIG. 3 is a battery module 4 as an example. Referring to FIG. 3, in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arbitrary arrangements can also be made. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0178] Optionally, the battery module 4 can further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0179] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and a person skilled in the art can select a suitable number according to the application and capacity of the battery pack.

[0180] FIGS. 4 and 5 are a battery pack 1 as an example. Referring to FIGS. 4 and 5, a battery case and a plurality of battery modules 4 disposed in the battery case can be included in the battery pack 1. The battery case includes an upper case 2 and a lower case 3, and the upper case 2 is capable of being disposed on the lower case 3 and forming an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery case in any manner.

[0181] In addition, the application also provides a power utilization device, which comprises the lithium ion battery provided by the application. The lithium ion battery can be used as a power supply of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device, an electric vehicle, an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto. Among them, the mobile device can be a mobile phone, a notebook computer, etc.; the electric vehicle can be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited thereto.

[0182] As the power utilization device, the lithium ion battery can be selected according to the use requirements thereof.

[0183] FIG. 6 is a power utilization device 6 as an example. The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the lithium ion battery for the power utilization device, a battery pack or a battery module can be used.

[0184] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and the lithium ion battery can be used as a power supply.

[0185] Hereinafter, the embodiments of the application are described. The embodiments described below are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application. If the technology or conditions are not specified in the embodiments, the technology or conditions are performed according to the technology or conditions described in the literature in the art or according to the product manual. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be obtained by purchase.

[0186] I. Preparation of the positive electrode sheet

[0187] Example 1

[0188] Step S1, a polycrystalline lithium-rich manganese-based positive electrode material Li 1.13 Ni 0.29 Co 0.03 Mn 0.54 Mg 0.02O2 (the first active material) and the single-crystal lithium-rich manganese-based positive electrode material II with Dv50 = 2.5 pm, SPAN = 1.4, and TD = 2.1 g / cm3 1.2 Ni 0.19 Mn 0.59 Al 0.02 O2 (the second active material) were mixed in a 5-L stirring tank in a mass ratio of 2.33:1 for 30 min to prepare a mixture of lithium-rich manganese-based positive electrode materials.

[0189] In step S2, the conductive agent acetylene black (SP) and the binder polyvinylidene fluoride (PVDF) were added to the stirring tank for secondary dry mixing for 30 min; finally, the solvent N-methyl pyrrolidone (NMP) was added, and rapid stirring was performed under vacuum to form a slurry. The mass ratio of the mixture of lithium-rich manganese-based positive electrode materials: acetylene black: polyvinylidene fluoride was 96:2:2, and the solid content of the slurry was 70 wt%.

[0190] In step S3, the slurry was uniformly coated on both sides of an aluminum foil with a thickness of 12 pm, and the coated electrode sheet was taken out after drying in an oven at 100-130 °C for half an hour. The positive active material loading of the electrode sheet was 13.5 mg / cm 2 .

[0191] Example 2-26

[0192] The preparation method of Example 2-26 was similar to that of Example 1, and the differences are shown in Tables 1-1 and 1-2.

[0193] The difference between the preparation method of Example 26 and that of Example 1 included that the same amount of the ternary positive electrode material LiNi 0.9 Co 0.0 5Mn 0.05 O2 was used to replace the single-crystal lithium-rich manganese-based positive electrode material II.

[0194] Comparative Example 1

[0195] The preparation method of Comparative Example 1 was different from that of Example 1 in that no second active material was used in Comparative Example 1, and the same amount of the first active material was used to replace the second active material, and the others were the same.

[0196] Comparative Example 2

[0197] The preparation method of Comparative Example 2 was different from that of Example 1 in that no first active material was used in Comparative Example 2, and the same amount of the second active material was used to replace the first active material, and the others were the same.

[0198] Comparative Examples 3-8

[0199] The preparation method of Comparative Example 3-8 is similar to that of Example 1, and the differences are shown in Table 1-2.

[0200] Table 1-1

[0201] Table 1-2

[0202] In Table 1-1 and Table 1-2, n refers to the mass ratio of the first active material and the second active material.

[0203] The lithium-rich manganese-based positive electrode material prepared in each of the above examples and comparative examples is tested for particle size span SPAN, volume distribution particle size Dv99, compaction density CPD and specific surface area BET, and the positive electrode sheet prepared is tested for compaction density and elongation rate; the test methods are as follows:

[0204] Particle size span SPAN and volume distribution particle size Dv50: referring to GB / T 19077-2016 / ISO 13320:2009 particle size distribution laser diffraction method, a laser particle size analyzer (Malvern 3000) is used to determine Dv10, Dv50 and Dv90, respectively, and then SPAN is calculated according to the formula (Dv90-Dv10) / Dv50.

[0205] Compaction density CPD of the positive electrode material: referring to GB / T 5162-2006 "Lithium ion battery graphite-based negative electrode material", a UTM7305 electronic pressure testing machine is used for determination.

[0206] Specific surface area BET: determined by referring to GB / T 19587-2004 gas adsorption BET method.

[0207] Compaction density of the positive electrode sheet: calculated by the formula PD=M / (d×A). In the formula, M is the mass of a small disc with a diameter of 40 mm cut out from the positive electrode sheet, and the average value of 10 weighings is taken; d is the thickness of the positive electrode sheet, and the average value of 10 thickness measurements is taken; and A is the area of the small disc with a diameter of 40 mm.

[0208] Elongation rate of the positive electrode sheet: calculated by the formula ΔEL%=(L2-L1) / L1×100%. In the 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 by the following method: in the central region of the sheet, three 1000 mm long line segments extending in the length direction of the sheet are taken at different positions in the width direction of the sheet, and the two end points of the line segments are marked. L2 is recorded as the average value of the measured values of the distances between the two end points of each line segment after cold pressing.

[0209] The test results of each of the above examples and comparative examples are shown in Table 2.

[0210] Table 2

[0211] II. Preparation and performance test of the battery

[0212] 1. Preparation of the lithium ion battery

[0213] 1) Positive electrode sheet: The positive electrode sheet prepared in Example 1 above was used.

[0214] 2) Preparation of the negative electrode sheet

[0215] After the negative electrode active material artificial graphite, hard carbon, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), thickening agent sodium carboxymethyl cellulose (CMC) were fully stirred and mixed uniformly in a weight ratio of 90:5:2:2:1 in a deionized water solvent system, they were coated on the double-sided surface of a copper foil, dried and cold-pressed to obtain a negative electrode sheet.

[0216] 3) Separator

[0217] A 13 μm thick polyethylene porous polymer film was selected as the separator.

[0218] 4) Preparation of the electrolyte

[0219] The organic solvent was a mixture containing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC), wherein the volume ratio of EC, EMC and DMC was 1:1:1. In an argon glove box with a water content <10 ppm, the fully dried lithium salt LiPF6 was dissolved in the organic solvent and mixed uniformly to obtain the electrolyte. The concentration of the lithium salt was 1 mol / L.

[0220] 5) Preparation of the battery

[0221] The positive electrode sheet, the separator and the negative electrode sheet were stacked in order, with the separator between the positive and negative electrode sheets to play a separating role, and then wound into a square bare cell, which was then placed in an aluminum plastic film, injected with the non-aqueous electrolyte prepared above, sealed, and subjected to the processes of standing, hot and cold pressing, formation, clamping, and capacity distribution to obtain the lithium ion battery.

[0222] The lithium ion batteries of Examples 2-26 and the lithium ion batteries of Comparative Examples 1-8 were prepared in a similar manner to the lithium ion battery of Example 1, but using the corresponding positive electrode material of the preparation examples or comparative examples.

[0223] 2. Preparation of the button cell

[0224] A CR2032 button cell was assembled in an argon-filled glove box. The order of assembly from top to bottom was positive shell, positive electrode prepared in Example 1, separator, negative electrode, steel sheet, spring sheet, and negative shell. After assembly, the button cell was allowed to stand for 6 hours before use.

[0225] The button cells of Examples 2-26 and Comparative Examples 1-8 were prepared in a similar manner to the button cell of Example 1, except that the corresponding positive electrode material of the preparation example or comparative example was used.

[0226] The lithium ion batteries prepared in each of the above examples and comparative examples were subjected to cycle performance testing, and the button cells prepared in each of the above examples and comparative examples were subjected to capacity testing.

[0227] Capacity testing: The button cell was used as the test object, and was charged at a rate of 0.1C to 4.55V at a voltage of 2.5V-4.55V, then was charged at a constant voltage of 4.55V until the current was ≤0.05mA, and was allowed to stand for 2min. At this time, the charge capacity was recorded as C0. Then the button cell was discharged at a rate of 0.1C to 2.5V, and the discharge capacity at this time was the initial gram capacity, recorded as D0. The first efficiency was D0 / C0*100%.

[0228] Cycle testing: The secondary battery was used as the test object, and was charged at a rate of 1C to 4.45V at a voltage of 2.5V-4.45V in a constant temperature environment of 25°C or 45°C, then was charged at a constant voltage of 4.45V until the current was ≤0.05mA, and was allowed to stand for 5min. Then the secondary battery was discharged at a rate of 1C to 2.5V, and the discharge capacity was recorded. The above process was repeated until the capacity decayed to 80%, and the number of cycles was recorded.

[0229] The test results of each of the above examples and comparative examples are shown in Table 3.

[0230] Table 3

[0231] As can be seen from the results of Examples 1-26 and Comparative Examples 1-8, the lithium-rich manganese-based positive electrode material provided in the present application has a suitable particle size span SPAN, volume distribution particle size Dv50, compaction density CPD, and specific surface area BET, which is conducive to improving the compaction density of the electrode sheet, reducing the elongation rate of the electrode sheet, and simultaneously improving the cycle performance of the battery.

[0232] The above description of each example tends to emphasize the differences between each example, and the same or similar parts can be mutually referred to. For brevity, the same or similar parts will not be described again herein.

[0233] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications to the embodiments, or by combining part of the configurations of the embodiments, which can be conceived by those skilled in the art, without departing from the spirit of the present application, are also included in the scope of the present application.

Claims

1. A lithium-rich manganese-based cathode material having a span of particle size, SPAN, of 1.6-2.0, a volume distribution particle size, Dv50, of 6.5 pm-10.1 pm, a compacted density, CPD, of 2.9 g / cm 3 -3.3 g / cm 3 , a specific surface area, BET, of 1.5 m 2 / g-3.5 m 2 / g.

2. The lithium-rich manganese-based positive electrode material of claim 1, wherein, The lithium-rich manganese-based positive electrode material comprises a first active material and a second active material, and the first active material and the second active material have different volume distribution particle sizes.

3. The lithium-rich manganese-based positive electrode material of claim 2, wherein, The volume distribution particle size Dv50 of the first active material is 6-10 μm, and the volume distribution particle size Dv50 of the second active material is 1.5-3.5 μm.

4. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 3, wherein, The first active material is a polycrystalline lithium-rich manganese-based positive electrode material, and the second active material is one or more of a single-crystal lithium-rich manganese-based positive electrode material, a polycrystalline lithium-rich manganese-based positive electrode material, and a lithium-nickel-based composite oxide.

5. The lithium-rich manganese-based positive electrode material of claim 4, wherein, The first active material is a polycrystalline lithium-rich manganese-based positive electrode material, and the second active material is a single-crystal lithium-rich manganese-based positive electrode material.

6. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 5, wherein, The mass ratio of the first active material to the second active material is (1.5-9):

1.

7. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 6, wherein, The volume distribution particle size Dv10 of the first active material is 0.5-2.5 μm.

8. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 7, wherein, The volume distribution particle size Dv99 of the first active material is 7-20 μm.

9. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 8, wherein, The volume distribution particle size Dv10 of the second active material is 0.5-2.5 μm.

10. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 9, wherein, The volume distribution particle size Dv99 of the second active material is 1-7.5 μm.

11. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 10, wherein, The particle size span SPAN of the first active material is 0.5-1.

2.

12. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 11, wherein, The particle size span SPAN of the second active material is 1.0-1.

8.

13. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 12, wherein, The specific surface area BET of the first active material is 1.3 m 2 / g-1.7 m 2 / g.

14. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 13, wherein, The specific surface area BET of the second active material is 1.5 m 2 / g-2.1 m 2 / g.

15. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 14, wherein, The first active material has a compacted density PD of 2.7 g / cm 3 - 3.1 g / cm 3 .

16. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 14, wherein, The second active material has a compacted density PD of 2.5 g / cm 3 - 2.8 g / cm 3 .

17. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 16, wherein, The first active material has a true density of 4.2 g / cm 3 - 4.45 g / cm 3 .

18. The lithium-rich manganese-based positive electrode material according to any one of claims 2 to 17, wherein, The second active material has a true density of 4.1 g / cm 3 - 4.35 g / cm 3 .

19. The lithium-rich manganese-based positive electrode material of any one of claims 2 to 18, wherein, The tap density TD of the first active material is ≥ 1.8 g / cm3 3 .

20. The lithium-rich manganese-based positive electrode material of any one of claims 2 to 19, wherein, The tap density TD of the second active material is ≥ 1.8 g / cm3 3 .

21. The lithium-rich manganese-based positive electrode material of any one of claims 2 to 20, wherein, Li[Li x Ni a Co b Mn c M d ]O 2-e Z e wherein x+a+b+c+d=1, x>0, a+b+c+d<1, 0 M elements include one or more of Te, Se, Mg, Nb, Cr, Ce, Fe, Ta, B, V, Ti, Sn, W, and Mo, and Z elements include one or more of F, Cl, and Br.

22. The lithium-rich manganese-based positive electrode material of any one of claims 2 to 21, wherein, Li[Li x1 Ni a1 Co b1 Mn c1 M1 d1 ]O 2-e1 Z1 e1 wherein x1+a1+b1+c1+d1=1, x1>0, a1+b1+c1+d1<1, 0 M1 includes one or more of Te, Se, Mg, Nb, Cr, Ce, Fe, Ta, B, V, Ti, Sn, W and Mo, and Z1 includes one or more of F, Cl and Br.

23. The lithium-rich manganese-based positive electrode material of claim 4, wherein, The lithium-nickel-based composite oxide is a lithium-containing nickel-cobalt-manganese metal oxide.

24. The lithium-rich manganese-based positive electrode material of claim 23, wherein, The lithium-nickel-based composite oxide further comprises one or more of a cobalt element, a manganese element, and an aluminum element, and the molar proportion of the nickel element in all metal elements except the lithium element is ≥80%.

25. A preparation method of a lithium-rich manganese-based positive electrode material, comprising the following steps: mixing the first active material and the second active material to prepare the lithium-rich manganese-based positive electrode material; wherein, The first active material and the second active material have different volume distribution particle sizes; The lithium-rich manganese-based positive electrode material has a particle size span SPAN of 1.6-2.0, a volume distribution particle size Dv50 of 6.5-10.1 μm, and a compacted density CPD of 2.9 g / cm 3 - 3.3 g / cm 3 , a specific surface area BET of 1.5 m 2 / g-3.5 m 2 / g.

26. A positive electrode sheet, comprising the lithium-rich manganese-based positive electrode material according to any one of claims 1-24.

27. The cathode sheet of Claim 26, wherein, The compacted density of the positive electrode plate is ≥ 2.86 g / cm 3 .

28. The cathode sheet of any one of claims 26-27, wherein, The positive electrode sheet has an elongation of ≤0.7%.

29. A lithium ion battery comprising the positive electrode sheet according to any one of claims 26-28.

30. An electric device comprising at least one of the positive electrode sheet according to any one of claims 26-28 and the lithium ion battery according to claim 29.

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