Batteries and electrical devices

Abstract

The present application provides a battery and an electrical device. The battery includes a housing, an electrode assembly, and an electrolyte. The housing has a receiving cavity, and the electrode assembly and the electrolyte are both arranged in the receiving cavity. The electrode assembly includes a positive electrode sheet, and the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer located on at least one surface of the positive electrode current collector. The positive electrode active layer includes a chemical formula of Li x (Ni a Co b Mn c ) 1‑d M d O 2‑y A y The positive electrode active material of the battery EL Meet 1.6g / Ah≤K EL ≤1.9g / Ah, K EL The ratio of the mass of the free electrolyte to the rated capacity of the battery is expressed in g / Ah. The space utilization rate of the battery η≥0.8, and the space utilization rate represents the ratio of the volume of the electrode assembly to the volume of the accommodating cavity. The battery can have both high energy density and good cycle performance.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery and an electrical device. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] Energy density is one of the important indicators reflecting battery performance. In order to improve the energy density of batteries, traditional methods often focus on the development of electrode active materials, and improve the energy density of batteries by looking for active materials with high gram capacity. Among them, positive electrode materials with higher nickel content have higher gram capacity, which may be beneficial to improve the energy density of batteries. However, when positive electrode materials with higher nickel content are used in batteries, it is difficult to effectively balance the energy density and cycle performance of the battery. Summary of the invention

[0004] The first aspect of the present application provides a battery, comprising a shell, an electrode assembly and an electrolyte; the shell has a receiving cavity inside, the electrode assembly and the electrolyte are both arranged in the receiving cavity; the electrode assembly comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer located on at least one surface of the positive electrode current collector; the positive electrode active layer comprises a chemical formula of Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y A positive electrode active material, wherein 0.2≤x≤1.2, 0.6≤a≤1, 0<b≤0.2, 0<c≤0.4, 0≤d<1, 0≤y<2, M includes at least one of Al, Mg, Fe, Cu, V, Ti, Zr, W, Sb, Dy and Te, and A includes at least one of P, S and halogen elements;

[0005] The battery K EL Meet 1.6g / Ah≤K EL ≤1.9g / Ah, K EL It represents the ratio of the mass of free electrolyte to the rated capacity of the battery, in g / Ah;

[0006] The space utilization ratio η of the battery is ≥ 0.8, and the space utilization ratio represents the ratio of the volume of the electrode assembly to the volume of the accommodating cavity.

[0007] In the above battery, by selecting a positive electrode material with a suitable nickel content and mixing the positive electrode material with the battery's K ELAnd space utilization is adapted, which is conducive to giving full play to the advantage of the positive electrode material's gram capacity, so that the battery has a higher energy density, and at the same time is conducive to improving the battery's cycle performance, so that the battery has a better cycle life, thereby enabling the battery to have both higher energy density and better cycle performance.

[0008] In some embodiments, 0.81≤η≤0.9. When the space utilization is within this range, the battery can have a relatively suitable expansion space inside the battery while taking into account both high energy density and good cycle performance, thereby reducing the risk of a large internal pressure of the battery during use.

[0009] In some embodiments, the electrode assembly further includes a negative electrode sheet, the negative electrode sheet including a negative electrode current collector and a negative electrode active layer located on at least one surface of the negative electrode current collector; wherein 1≤k≤1.15, k represents the ratio of the projected area of ​​the negative electrode active layer on the negative electrode current collector to the projected area of ​​the positive electrode active layer on the positive electrode current collector. When k is within this range, the positive electrode sheet and the negative electrode sheet can be better matched, and the risk of lithium deposition on the negative electrode sheet can be reduced.

[0010] In some embodiments, the surface density of the negative electrode active layer is 0.12 g / 1540.25 mm 2 ~0.2g / 1540.25mm 2 The surface density of the negative electrode active layer within this range can make the negative electrode sheet have a higher energy density, better match with the positive electrode sheet, and better promote the use of the capacity of the positive electrode active material.

[0011] In some embodiments, the thickness of the negative electrode current collector is 4 μm to 8 μm. The thickness of the negative electrode current collector within this range can make the negative electrode sheet have good stability, and at the same time, it can promote the increase of the thickness of the negative electrode active layer on the basis of maintaining the appropriate thickness of the negative electrode sheet, which is conducive to further improving the energy density of the negative electrode sheet.

[0012] In some embodiments, the thickness of the positive electrode current collector is 9 μm to 15 μm. The thickness of the positive electrode current collector can be relatively small. On the basis of maintaining a high energy density and a good cycle life, the thickness of the positive electrode current collector is relatively small, which can reduce the weight of the battery on the one hand, and increase the amount of positive electrode active material on the other hand, further improving the energy density of the battery.

[0013] In some embodiments, the surface density of the positive electrode active layer is 0.21 g / 1540.25 mm 2 ~0.32g / 1540.25mm 2 The surface density of the positive electrode active layer within this range can make the positive electrode active material have a more appropriate usage amount, which is conducive to making the battery have a higher energy density.

[0014] In some embodiments, the compaction density of the positive electrode sheet is 3.2 g / cm 3 ~3.7g / cm 3 The compaction density of the positive electrode sheet is within this range, which can improve the energy density of the battery while maintaining a suitable thickness of the positive electrode active layer, reduce the adverse effects of material expansion on the battery cycle performance during the charge and discharge process, and thus improve the cycle life of the battery.

[0015] In some embodiments, the positive electrode active material includes single crystal particles. There are almost no grain boundaries between the single crystal particles. During the cycle, the probability of intercrystalline cracks in the single crystal particles is low, so the side reaction between the positive electrode plate and the electrolyte can be alleviated, thereby extending the cycle life of the battery.

[0016] In some embodiments, the single crystal particles include first single crystal particles and second single crystal particles, and the particle size of the first single crystal particles is smaller than the particle size of the second single crystal particles. By combining the first single crystal particles and the second single crystal particles with different particle sizes, the damage of the active material to the positive electrode current collector during the compaction process can be further reduced, and the cycle performance of the battery can be further improved.

[0017] In some embodiments, the particle size ratio of the first single crystal particle to the second single crystal particle is (0.1-0.5): 1. Within this particle size ratio range, the first single crystal particle and the second single crystal particle are better adapted, which is beneficial to improve the compaction density of the positive electrode sheet and further promote the improvement of the battery energy density.

[0018] In some embodiments, the positive electrode plate further includes a primer layer; the primer layer is located between the positive active layer and the positive current collector, and the primer layer contains a conductive agent. The provision of the primer layer can, on the one hand, alleviate the damage of the active material to the positive current collector during the compaction process, thereby increasing the compaction density of the positive active layer and further increasing the energy density of the battery. At the same time, the damage to the positive current collector is reduced, so that the positive electrode plate can maintain a relatively stable structure during the battery cycle, which is beneficial to improving the battery cycle performance. On the other hand, the contact between the electrolyte and the positive current collector can be reduced, which can reduce the degree of corrosion of the electrolyte to the positive current collector. The reduced degree of corrosion of the positive current collector is beneficial to maintaining a relatively stable structure of the positive electrode plate during the battery cycle, which is beneficial to improving the battery cycle performance.

[0019] In some embodiments, the thickness of the primer layer is 0.5 μm to 2 μm. Within this range, the thickness of the primer layer can maintain a suitable thickness of the positive electrode sheet and thus a suitable volume of the battery while alleviating damage to the positive electrode collector and reducing contact between the electrolyte and the positive electrode collector.

[0020] In some embodiments, the mass percentage of the conductive agent in the base coating is 40% to 60%. In this case, the conductive coating has good conductivity, which is beneficial to improving the conductivity of the positive electrode sheet.

[0021] In some embodiments, the conductive agent includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0022] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium difluorobis(oxalyl)phosphate. The cycle life of the battery can be further improved by selecting the lithium salt.

[0023] In some embodiments, the molar concentration of the lithium salt in the electrolyte is 1.1 mol / L to 1.5 mol / L. The molar concentration of the lithium salt within this range is beneficial to further improve the cycle life of the battery.

[0024] In some embodiments, the electrolyte includes an additive, and the additive includes at least one of lithium bis(fluorosulfonyl)imide, lithium difluorobis(oxalyl)phosphate, and fluoroethylene carbonate. The selection of the additive is conducive to further improving the cycle life of the battery.

[0025] A second aspect of the present application provides an electric device, wherein the electric device comprises the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to better describe and illustrate the embodiments or examples provided by the present application, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the embodiments or examples currently described, and any of the best modes of these applications currently understood. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0027] Figure 1 It is a schematic diagram of a battery cell according to an embodiment of the present application.

[0028] Figure 2 for Figure 1 An exploded view of a battery cell according to an embodiment of the present application is shown.

[0029] Figure 3 A schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0030] Description of reference numerals:

[0031] 1. Battery cell; 11. Shell; 12. Electrode assembly; 13. Cover plate; 2. Electrical device. DETAILED DESCRIPTION

[0032] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0034] The "range" disclosed in the present application can be limited in the form of a lower limit and an upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The range limited in this way can be including or excluding end values, and any end value can be included or not included independently, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a specific parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are also listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents the abbreviation of any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to listing the parameter as, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0035] In the present application, "plurality", "multiple" and the like, unless otherwise specified, refer to a number greater than or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0036] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0037] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments. The "implementation methods" mentioned herein have a similar understanding.

[0038] Those skilled in the art will appreciate that, in the methods of various embodiments or examples, the order in which each step is written does not mean a strict order of execution and does not constitute any limitation on the implementation process, and the detailed order of execution of each step should be determined by its function and possible internal logic. If there is no special explanation, all steps of the present application can be performed sequentially or randomly, and in some embodiments, they are performed sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0039] In this application, in the open technical features or technical solutions described by the words "contain", "include", "include", etc., if there is no other explanation, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions including additional members in addition to the listed members. For example, A includes a1, a2 and a3. If there is no other explanation, it may also include other members or may not include additional members. It can be regarded as providing both the feature or solution of "A consists of a1, a2 and a3" and the feature or solution of "A includes not only a1, a2 and a3, but also other members".

[0040] In this application, unless otherwise specified, 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.

[0041] In this application, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel schemes of "yes" or "no". If there are multiple "options" in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "option" is independent.

[0042] In one embodiment of the present application, a battery is provided, including a housing, an electrode assembly, and an electrolyte. The housing has a receiving cavity inside, and the electrode assembly and the electrolyte are both arranged in the receiving cavity. The electrode assembly includes a positive electrode sheet, and the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer located on at least one surface of the positive electrode current collector. The positive electrode active layer includes a chemical formula of Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y The positive electrode active material, wherein 0.2≤x≤1.2, 0.6≤a≤1, 0<b≤0.2, 0<c≤0.4, 0≤d<1, 0≤y<2, M includes at least one of Al, Mg, Fe, Cu, V, Ti, Zr, W, Sb, Dy and Te, and A includes at least one of P, S and halogen elements. The K of the battery EL Meet 1.6g / Ah≤K EL ≤1.9g / Ah, K EL It indicates the ratio of the mass of free electrolyte to the rated capacity of the battery, in units of g / Ah. The space utilization rate of the battery η≥0.8, and the space utilization rate indicates the ratio of the volume of the electrode assembly to the volume of the accommodating cavity.

[0043] In the battery of this embodiment, by selecting a positive electrode material with a suitable nickel content and mixing the positive electrode material with the K EL The adaption of the positive electrode material to the space utilization rate is conducive to giving full play to the advantages of the positive electrode material in terms of gram capacity, so that the battery has a higher energy density, and at the same time is conducive to improving the cycle performance of the battery, so that the battery has a better cycle life, and thus the battery can take into account both higher energy density and better cycle performance. For example, the energy density of the battery in one embodiment of the present application can reach more than 280Wh / kg.

[0044] Furthermore, in general, the compaction density of the positive electrode active material with a higher nickel content is lower. In order to obtain a higher energy density, the thickness of the positive electrode active layer may be larger, which may cause the expansion of the electrode sheet to be more obvious during the charge and discharge process, thereby affecting the cycle life of the battery. EL By adapting the space utilization, the battery can have both higher energy density and better cycle life.

[0045] It is understood that the battery shell is usually square or cylindrical. The accommodating cavity of the square shell is correspondingly square. The accommodating cavity of the cylindrical shell is correspondingly cylindrical. When the battery shell is square, the space utilization ratio η=(length of the electrode assembly / length of the accommodating cavity)×(width of the electrode assembly / width of the accommodating cavity). When the battery shell is cylindrical, the space utilization ratio η=(diameter of the electrode assembly / diameter of the accommodating cavity)×(height of the electrode assembly / height of the accommodating cavity).

[0046] It is understood that when the battery housing is square, the width of the electrode assembly and the width of the accommodating cavity respectively represent the width of the electrode assembly and the width of the accommodating cavity in the same direction. The length of the electrode assembly and the length of the accommodating cavity respectively represent the length of the electrode assembly and the length of the accommodating cavity in the same direction. Optionally, the direction of the width is perpendicular to the direction of the length.

[0047] Optionally, the free electrolyte in this application can be tested by the following method: weigh the battery, and record the mass as m1. Disassemble the battery, remove the electrolyte in the shell, soak the electrode plate in DMC for 16 hours, dry it, weigh the mass of the shell and electrode assembly, and record the mass as m2. The mass of the free electrolyte is m1-m2, that is, the amount of free electrolyte.

[0048] Optionally, the rated capacity of the battery in the present application can be tested in the following manner: the battery is charged to 4.25V at a constant current of 0.33C, and then charged to a cut-off current of 0.05C at a constant voltage. Then, it is discharged to 2.8V at 0.33C, and the discharge capacity is recorded as the rated capacity of the battery.

[0049] In some embodiments, 0.81≤η≤0.9. When the space utilization ratio is within this range, the battery can have a more suitable expansion space inside the battery while taking into account both higher energy density and better cycle performance, thereby reducing the risk of a greater internal pressure of the battery during use. Optionally, the space utilization ratio η can be 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, and any value within the range consisting of any two of the above values.

[0050] It can be understood that when 0.6≤a≤1, the positive electrode active material has a higher nickel content and a higher gram capacity, which is conducive to maintaining a higher energy density of the battery. Optionally, a can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, and any value within the range of any two of the above values. Further optionally, 0.8≤a≤1. Further optionally, Li x (Ni a Co b Mn c ) 1-dM d O 2-y A y It can be LiNi 0.6 Co 0.2 Mn 0.2 O2、LiNi 0.7 Co 0.1 Mn 0.2 O2、LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.92 Co 0.06 Mn 0.02 O2, etc.

[0051] As some optional examples of x, x can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, and any value within the range consisting of any two of the above values.

[0052] As some optional examples of b, b can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, and any value within the range consisting of any two of the above values.

[0053] As some optional examples of c, c can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4 and any value within the range formed by any two of the above values.

[0054] In some embodiments, 0≤d<1, for example, d can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and any value within the range formed by any two of the above values. Optionally, 0≤d≤0.05.

[0055] In some embodiments, 0≤y<2, for example, y can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 and any value in the range formed by any two of the above values. Optionally, 0≤y≤0.05.

[0056] It can be understood that A includes at least one of P, S and halogen elements, wherein the halogen element can be F, Cl, Br and the like.

[0057] Optionally, the battery K EL It can be 1.6 g / Ah, 1.65 g / Ah, 1.7 g / Ah, 1.75 g / Ah, 1.8 g / Ah, 1.85 g / Ah, 1.9 g / Ah, or any value within the range consisting of any two of the above values. Further optionally, 1.67 g / Ah≤K EL ≤1.85g / Ah.

[0058] Optionally, the space utilization rate η of the battery can be 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, and any value within the range consisting of any two of the above values.

[0059] In some embodiments, the electrode assembly further includes a negative electrode sheet, the negative electrode sheet including a negative electrode current collector and a negative electrode active layer located on at least one surface of the negative electrode current collector; wherein 1≤k≤1.15, k represents the ratio of the projected area of ​​the negative electrode active layer on the negative electrode current collector to the projected area of ​​the positive electrode active layer on the positive electrode current collector. k in this range can make the positive electrode sheet and the negative electrode sheet better fit, and reduce the risk of lithium deposition in the negative electrode sheet. Optionally, k can be 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15 and any value within the range consisting of any two of the above values.

[0060] In some embodiments, the surface density of the negative electrode active layer is 0.12 g / 1540.25 mm 2 ~0.2g / 1540.25mm 2 , i.e. 0.12g / 1540.25mm 2 ≤CW A ≤0.2g / 1540.25mm 2 .CWA Within this range, the negative electrode sheet can have a higher energy density, better match the positive electrode sheet, and better promote the use of the capacity of the positive electrode active material. A Can be 0.12g / 1540.25mm 2 , 0.13g / 1540.25mm 2 , 0.14g / 1540.25mm 2 , 0.15g / 1540.25mm 2 , 0.16g / 1540.25mm 2 , 0.17g / 1540.25mm 2 , 0.18g / 1540.25mm 2 , 0.19g / 1540.25mm 2 , 0.2g / 1540.25mm 2 and any value within the range consisting of any two of the above values.

[0061] In some embodiments, the thickness of the negative electrode current collector is 4 μm to 8 μm. The thickness of the negative electrode current collector within this range can make the negative electrode sheet have good stability, and at the same time, on the basis of maintaining the appropriate thickness of the negative electrode sheet, it can promote the increase of the thickness of the negative electrode active layer, which is conducive to further improving the energy density of the negative electrode sheet. Optionally, the thickness of the negative electrode current collector can be 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, and any value within the range consisting of any two of the above values.

[0062] In some embodiments, the compaction density of the negative electrode sheet is 1.2 g / cm 3 ~1.8g / cm 3 Optionally, the compaction density of the negative electrode sheet can be 1.2 g / cm 3 , 1.3g / cm 3 , 1.4g / cm 3 , 1.5g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 , 1.8g / cm 3 and any value within the range consisting of any two of the above values.

[0063] In some embodiments, the thickness of the positive electrode current collector is 9 μm to 15 μm. In this embodiment, the thickness of the positive electrode current collector can be small. On the basis of maintaining a high energy density and a good cycle life, the thickness of the positive electrode current collector is small, which can reduce the weight of the battery on the one hand, and increase the amount of positive electrode active material on the other hand, further improving the energy density of the battery. Optionally, the thickness of the positive electrode current collector is ≤ 13 μm. Optionally, the thickness of the positive electrode current collector can be 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, and any value within the range consisting of any two of the above values.

[0064] In some embodiments, the surface density CW of the positive electrode active layer is C 0.21g / 1540.25mm 2 ~0.32g / 1540.25mm 2 The surface density of the positive electrode active layer within this range can make the positive electrode active material have a more appropriate usage amount, which is conducive to making the battery have a higher energy density. Optionally, the surface density of the positive electrode active layer can be 0.21g / 1540.25mm 2 , 0.22g / 1540.25mm 2 , 0.23g / 1540.25mm 2 , 0.24g / 1540.25mm 2 , 0.25g / 1540.25mm 2 , 0.26g / 1540.25mm 2 , 0.27g / 1540.25mm 2 , 0.28g / 1540.25mm 2 , 0.29g / 1540.25mm 2 , 0.3g / 1540.25mm 2 , 0.31g / 1540.25mm 2 and any value within the range consisting of any two of the above values.

[0065] In some embodiments, the compaction density of the positive electrode sheet is 3.2 g / cm 3 ~3.7g / cm 3 The compaction density of the positive electrode sheet is within this range, which can improve the energy density of the battery while maintaining a suitable thickness of the positive electrode active layer, reduce the adverse effect of material expansion on the battery cycle performance during the charge and discharge process, and thus improve the cycle life of the battery. Optionally, the compaction density of the positive electrode sheet can be 3.2g / cm 3 , 3.3g / cm 3 、3.4g / cm 3 , 3.5g / cm3 、3.6g / cm 3 、3.7g / cm 3 etc. and any value within the range consisting of any two of the above values.

[0066] Optionally, in this application, CW A The test can be done as follows: Punch the negative electrode sheet to obtain 1540.25mm 2 Remove the negative electrode active layer, use NMP to clean the negative electrode current collector, and weigh the negative electrode current collector. Subtract the mass of the negative electrode current collector from the mass of the small disc to get CW. A The thickness of the negative electrode current collector after washing was measured.

[0067] In this application, CW C The test can be done as follows: Punch the positive electrode sheet to obtain 1540.25mm 2 After removing the positive electrode active layer and cleaning the positive electrode current collector with NMP, weigh the positive electrode current collector. Subtract the mass of the positive electrode current collector from the mass of the small disc to get CW C The thickness of the positive electrode current collector after washing was measured.

[0068] In some embodiments, the positive electrode active material includes single crystal particles. There are almost no grain boundaries between the single crystal particles. During the cycle, the probability of intercrystalline cracks in the single crystal particles is low, so the side reaction between the positive electrode plate and the electrolyte can be alleviated, thereby extending the cycle life of the battery. In addition, the single crystal particles can effectively inhibit the irreversible phase change of the material from the H2 crystal phase to the H3 crystal phase during the charge and discharge process, further improving the cycle performance of the battery.

[0069] In some embodiments, the single crystal particles include first single crystal particles and second single crystal particles, and the particle size of the first single crystal particles is smaller than the particle size of the second single crystal particles. By combining the first single crystal particles and the second single crystal particles with different particle sizes, the damage of the active material to the positive electrode current collector during the compaction process can be further reduced, and the cycle performance of the battery can be further improved.

[0070] It can be understood that the size relationship between the first single crystal particle and the second single crystal particle can be tested by the following method: cutting a cross section along the thickness direction of the positive electrode plate, observing the cross section through a scanning electron microscope (SEM), and then obtaining the size relationship between the first single crystal particle and the second single crystal particle.

[0071] Optionally, the particle size ratio of the first single crystal particle and the second single crystal particle is (0.1-0.5):1. Within this particle size ratio range, the first single crystal particle and the second single crystal particle are better adapted, which is conducive to improving the compaction density of the positive electrode sheet and further promoting the improvement of the battery energy density. Optionally, the particle size ratio of the first single crystal particle and the second single crystal particle can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, and any value within the range consisting of any two of the above values.

[0072] In some embodiments, the positive electrode plate further includes a primer layer. The primer layer is located between the positive electrode active layer and the positive electrode current collector, and the primer layer contains a conductive agent. The provision of the primer layer can, on the one hand, alleviate the damage of the active material to the positive electrode current collector during the compaction process, thereby increasing the compaction density of the positive electrode active layer and further increasing the energy density of the battery. At the same time, the damage to the positive electrode current collector is reduced, so that the positive electrode plate can maintain a relatively stable structure during the battery cycle, which is beneficial to improving the battery cycle performance. On the other hand, the contact between the electrolyte and the positive electrode current collector can be reduced, which can reduce the degree of corrosion of the electrolyte to the positive electrode current collector. The degree of corrosion of the positive electrode current collector is reduced, which is beneficial to maintaining a relatively stable structure of the positive electrode plate during the battery cycle, which is beneficial to improving the battery cycle performance. It is understandable that the primer layer can be prepared by a gravure process.

[0073] Optionally, the thickness of the primer layer is 0.5 μm to 2 μm. The thickness of the primer layer within this range can maintain a more suitable thickness of the positive electrode sheet on the basis of alleviating damage to the positive electrode current collector and reducing the contact between the electrolyte and the positive electrode current collector, thereby maintaining a more suitable volume of the battery. For example, the thickness of the primer layer can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, and any value within the range consisting of any two of the above values.

[0074] Optionally, the mass percentage of the conductive agent in the base coating is 40% to 60%. In this case, the conductive coating has good conductivity, which is beneficial to improve the conductivity of the positive electrode sheet. Optionally, the mass percentage of the conductive agent in the base coating can be 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, and any value within the range of any two of the above values.

[0075] Optionally, the conductive agent includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0076] In some embodiments, the primer layer further comprises a binder, which is beneficial to improve the adhesion between the positive electrode active layer and the positive electrode current collector. Optionally, the binder comprises polyacrylate.

[0077] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium difluorobis(oxalate)phosphate. By selecting the lithium salt, the cycle life of the battery can be further improved. Optionally, the molar concentration of the lithium salt in the electrolyte is 1.1 mol / L to 1.5 mol / L. The molar concentration of the lithium salt within this range is conducive to further improving the cycle life of the battery. Optionally, the molar concentration of the lithium salt in the electrolyte can be 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, and any value within the range consisting of any two of the above values.

[0078] In some embodiments, the electrolyte includes an additive, and the additive includes at least one of lithium bis(fluorosulfonyl)imide, lithium difluorobis(oxalyl)phosphate, and fluoroethylene carbonate. The selection of the additive is conducive to further improving the cycle life of the battery.

[0079] Another embodiment of the present application provides an electric device, which includes the above-mentioned battery.

[0080] The battery and the electrical device of the present application will be described below with reference to the accompanying drawings as appropriate.

[0081] Typically, a battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the battery charge and discharge process, active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0082] Positive electrode

[0083] The positive electrode sheet includes a positive electrode current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active layer includes a positive electrode active material.

[0084] As a non-limiting example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0085] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, non-limiting examples of the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the positive electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0086] In some of the embodiments, the positive electrode active layer may also optionally include a positive electrode active material for a battery known in the art. As non-limiting examples, these positive electrode active materials may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds. Among them, examples of lithium transition metal oxides may 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 their modified compounds. Non-limiting examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may 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 0.1Mn 0.1 O2 (also referred to as NCM 811 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.8 Co 0.15 Al 0.05 O2.

[0087] In some embodiments, Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y The mass percentage of the positive electrode active material in the positive electrode active layer is 90%~100%.

[0088] In some embodiments, the positive electrode active layer may further include a binder. As non-limiting examples, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0089] In some embodiments, the positive electrode active layer may further include a conductive agent. As non-limiting examples, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0090] In some of the embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent to form a positive electrode slurry; the positive electrode slurry is coated on at least one side of the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained. The type of solvent can be selected from but not limited to any one of the aforementioned embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector. The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector. The solid content of the positive electrode slurry can be 40wt%~80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000mPa·s~25000mPa·s.

[0091] Negative electrode

[0092] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active layer includes a negative electrode active material.

[0093] As a non-limiting example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0094] In some of the 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 material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the negative electrode current collector, non-limiting examples of the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the negative electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0095] In some of the embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As a non-limiting example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may include one or more of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional 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.

[0096] In some embodiments, the negative electrode active layer may further include a binder. The binder may 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).

[0097] In some embodiments, the negative electrode active layer may further include a conductive agent, which may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0098] In some of the embodiments, the negative electrode active layer may further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0099] In some of the embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained. The surface of the negative electrode collector coated with the negative electrode slurry can be on a single surface of the negative electrode collector or on both surfaces of the negative electrode collector. The solid content of the negative electrode slurry can be 40wt%~60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000mPa·s~10000mPa·s.

[0100] Electrolytes

[0101] The electrolyte has the function of conducting ions between the positive electrode and the negative electrode. The present application has no particular restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0102] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0103] In some of the embodiments, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0104] In some embodiments, the solvent may include ethylene carbonate (EC, ), propylene carbonate (PC, )、ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate ( ), fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0105] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0106] In some embodiments, the additive in the electrolyte may include, but is not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), and the like.

[0107] Isolation film

[0108] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0109] In some embodiments, the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0110] In some embodiments, the isolation film has a thickness of 6 μm to 40 μm, and may be 12 μm to 20 μm.

[0111] In some of the embodiments, the positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly by a winding process or a lamination process.

[0112] In some embodiments, the battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0113] In some embodiments, the outer packaging of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and further, non-limiting examples of plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0114] The battery includes at least one battery cell. The battery may include one or more battery cells.

[0115] In this application, unless otherwise specified, "battery cell" refers to a basic unit that can realize the mutual conversion of chemical energy and electrical energy, and further, generally speaking, at least includes a positive electrode sheet, a negative electrode sheet and an electrolyte. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting active ions between the positive electrode sheet and the negative electrode sheet.

[0116] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. Figure 1 The battery cell 1 is a square structure as an example. It can be understood that the cylindrical battery cell includes a cylindrical shell with a cylindrical receiving cavity inside. The square battery cell includes a square shell with a square receiving cavity inside.

[0117] In some of these embodiments, reference Figure 2 , the outer packaging may include a shell 11 and a cover plate 13. Among them, the shell 11 may 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 shell 11 has an opening connected to the receiving cavity, and the cover plate 13 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 12 through a winding process or a lamination process. The electrode assembly 12 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 12. The number of electrode assemblies 12 contained in the battery cell 1 can be one or more, and those skilled in the art can select according to actual needs.

[0118] The battery may be a battery module or a battery pack.

[0119] 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 those skilled in the art can select a suitable number according to the application and capacity of the battery module.

[0120] In the battery module, the plurality of battery cells may be arranged in sequence along the length direction of the battery module. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells may be fixed by fasteners.

[0121] Optionally, the battery module may further include a housing having an accommodation space, and the plurality of battery cells are accommodated in the accommodation space.

[0122] In some of the embodiments, the battery modules may be assembled into a battery pack. The battery pack may contain one or more battery modules. Those skilled in the art may select a suitable number according to the application and capacity of the battery pack.

[0123] The battery pack may include a battery box and a plurality of battery modules disposed in the battery box. The battery box includes an upper box body and a lower box body, and the upper box body can be covered on the lower box body to form a closed space for accommodating the battery modules. The plurality of battery modules can be arranged in the battery box in any manner.

[0124] In addition, the present application also provides an electrical device, which includes the battery provided in the present application. The battery 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 mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto. Among them, the mobile device may be, for example, a mobile phone, a laptop computer, etc.; the electric vehicle may be, for example, 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 are not limited thereto.

[0125] As an electrical device, a battery can be selected according to its usage requirements.

[0126] Figure 3 The power consumption device 2 is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the power consumption device's requirements for high power and high energy density of the battery, a battery pack or a battery module can be used.

[0127] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery may be used as a power source.

[0128] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0129] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0130] Example 1

[0131] In this embodiment, the positive electrode active material is LiNi 0.6 Co 0.2 Mn 0.2 O2.

[0132] (1) Preparation of positive electrode.

[0133] The positive electrode active material, the binder polyvinylidene fluoride, and the conductive agent acetylene black are mixed in a weight ratio of 98:1:1, N-methylpyrrolidone is added as a solvent, and the slurry is stirred in a vacuum state until it is uniform to obtain a positive electrode slurry. The positive electrode slurry is coated on an aluminum foil, dried, and cold pressed to obtain a positive electrode sheet.

[0134] (2) Preparation of negative electrode sheets.

[0135] Graphite, binder styrene butadiene rubber, and conductive agent acetylene black were stirred and mixed at a mass ratio of 98:1:1 at a speed of 800r / s, and then wetted, kneaded, and dispersed to obtain negative electrode slurry. The negative electrode slurry was coated on copper foil, dried, and cold pressed to obtain a negative electrode sheet.

[0136] (3) Preparation of electrolyte.

[0137] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:7, 12.5 wt% (based on the total weight of ethylene carbonate and ethyl methyl carbonate solvents) of LiPF6 was added and dissolved in the above organic solvent, and stirred evenly to obtain an electrolyte.

[0138] (4) The separator used was a commercially available PP-PE copolymer microporous film with a thickness of 7 μm and an average pore size of 80 nm.

[0139] (5) The negative electrode sheet, the separator, and the positive electrode sheet are stacked and wound in order to obtain a wound battery cell. The battery cell is placed in a square aluminum shell for outer packaging, dried, and then injected with electrolyte. After packaging, standing, formation, aging, secondary packaging, capacity, and other processes, a battery is obtained.

[0140] Example 2 to Example 11, Comparative Example 1 to Comparative Example 3

[0141] Compared with Example 1, the differences between Examples 2 to 11 and Comparative Examples 1 to 3 are: the type of positive electrode active material, the particle composition of the positive electrode active material, the compaction density PD of the positive electrode sheet C , the compaction density PD of the negative electrode A , the surface density of the positive electrode active layer CW C , the surface density of the negative electrode active layer CW A , battery K EL, the space utilization rate η of the battery, and the ratio k of the projected area of ​​the negative electrode active layer on the negative electrode current collector to the projected area of ​​the positive electrode active layer on the positive electrode current collector are different, as shown in Table 1. In Example 4, the battery adopts a lamination process to obtain a laminated battery. When the positive electrode active material includes a first single crystal and a second single crystal, in the corresponding embodiment, the difference between the first single crystal and the second single crystal is that the particle size is different.

[0142] Test Case

[0143] (1) Battery energy density test.

[0144] The test method is: charge the battery cell at a constant current of 0.33C to 4.25V, then charge at a constant voltage to a cut-off current of 0.05C; then discharge the battery cell at a constant current of 0.33C to 2.8V, and record the discharge energy (in Wh). Weigh the mass of the battery cell (in kg), and calculate the energy density per unit mass of the battery cell from the discharge energy / mass, in Wh / kg. The test results are shown in Table 1.

[0145] (2) Battery cycle performance test.

[0146] The test method is: test the capacity of the battery before cycling; charge at 0.5C constant current to 97% SOC, the cut-off voltage is 4.17V, charge at 4.17V constant voltage to 0.05C; discharge at 0.5C to 5% SOC, the cut-off voltage is 3.33V; repeat 100 cycles, test the capacity of the battery after cycling, and calculate the cycle retention rate after 100 cycles. The test results are shown in Table 1. During the cycle process, when the capacity retention rate deviates significantly from the normal downward trend, it is considered that the cycle has dived.

[0147] Table 1

[0148]

[0149] In Table 1, in the column of particle composition, "first single crystal" means that the particle composition of the positive electrode active material is the first single crystal particle. "First: second" means that the particle composition of the positive electrode active material is a mixture of the first single crystal particle and the second single crystal particle according to the corresponding particle size ratio. C Indicates the compaction density of the positive electrode sheet, in g / cm 3 . PD A Indicates the compaction density of the negative electrode sheet, in g / cm 3 .CW C Indicates the surface density of the positive electrode active layer, in g / 1540.25mm 2 .CW A Indicates the surface density of the negative electrode active layer, in g / 1540.25mm 2 . K ELThe unit is g / Ah. η represents the space utilization rate of the battery. k represents the ratio of the projected area of ​​the negative electrode active layer on the negative electrode current collector to the projected area of ​​the positive electrode active layer on the positive electrode current collector. Energy density represents the energy density per unit mass of the battery cell, in Wh / kg. Capacity retention rate represents the capacity retention rate after 100 cycles of the battery, in %. "Wh" represents whether the battery cycle has a drop during the cycle, where "No" means no drop and "Yes" means drop.

[0150] As can be seen from Table 1, by comparing the embodiment and the comparative example, it can be seen that the battery in the embodiment has a higher energy density, indicating that when the nickel content of the positive electrode active material is high, when the K EL And space utilization meets 1.6g / Ah≤K EL When ≤1.9g / Ah and η≥0.8, a higher energy density can be exhibited.

[0151] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0152] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A battery, characterized in that: The invention comprises a shell, an electrode assembly and an electrolyte; the shell has a receiving cavity inside, and the electrode assembly and the electrolyte are both arranged in the receiving cavity; the electrode assembly comprises a positive electrode sheet and a negative electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer located on at least one surface of the positive electrode current collector; the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer located on at least one surface of the negative electrode current collector; the positive electrode active layer comprises a chemical formula of Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y A positive electrode active material, wherein 0.2≤x≤1.2, 0.8<a≤1, 0<b≤0.2, 0<c≤0.4, 0≤d<1, 0≤y<2, M includes at least one of Al, Mg, Fe, Cu, V, Ti, Zr, W, Sb, Dy and Te, and A includes at least one of P, S and halogen elements; the surface density of the positive electrode active layer is 0.21g / 1540.25mm 2 ~0.32g / 1540.25mm 2 The compaction density of the positive electrode sheet is 3.2 g / cm 3 ~3.7g / cm 3 ; The surface density of the negative electrode active layer is 0.12g / 1540.25mm 2 ~0.2g / 1540.25mm 2 ; The battery K EL Meet 1.6g / Ah≤K EL ≤1.9g / Ah, K EL It represents the ratio of the mass of free electrolyte to the rated capacity of the battery, in g / Ah; The space utilization rate of the battery is 0.8≤η≤0.9, and the space utilization rate represents the ratio of the volume of the electrode assembly to the volume of the accommodating cavity.

2. The battery according to claim 1, characterized in that 1≤k≤1.15, k represents the ratio of the projected area of ​​the negative electrode active layer on the negative electrode current collector to the projected area of ​​the positive electrode active layer on the positive electrode current collector.

3. The battery according to claim 2, characterized in that The thickness of the negative electrode current collector is 4 μm to 8 μm.

4. The battery according to claim 1, characterized in that 0.81≤η≤0.

9.

5. The battery according to claim 1, characterized in that The thickness of the positive electrode current collector is 9 μm to 15 μm.

6. The battery according to any one of claims 1 to 5, characterized in that The positive electrode active material includes single crystal particles.

7. The battery according to claim 6, characterized in that The single crystal particles include first single crystal particles and second single crystal particles, and the particle size of the first single crystal particles is smaller than the particle size of the second single crystal particles.

8. The battery according to claim 7, characterized in that The particle size ratio of the first single crystal particle to the second single crystal particle is (0.1-0.5):

1.

9. The battery according to any one of claims 1 to 5, characterized in that The positive electrode plate further includes a primer layer; the primer layer is located between the positive electrode active layer and the positive electrode current collector, and the primer layer contains a conductive agent.

10. The battery according to claim 9, characterized in that The thickness of the primer layer is 0.5 μm to 2 μm; and / or, The mass percentage of the conductive agent in the primer layer is 40% to 60%; and / or, The conductive agent includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

11. The battery according to any one of claims 1 to 5, characterized in that The electrolyte includes a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium difluorobis(oxalate)phosphate.

12. The battery according to claim 11, characterized in that The molar concentration of the lithium salt in the electrolyte is 1.1 mol / L to 1.5 mol / L.

13. The battery according to any one of claims 1 to 5, characterized in that The electrolyte includes an additive, and the additive includes at least one of lithium bis(fluorosulfonyl)imide, lithium difluorobis(oxalyl)phosphate, and fluoroethylene carbonate.

14. An electrical device, characterized in that: A battery comprising the battery according to any one of claims 1 to 13.

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