Battery and electric device

Abstract

A battery and an electric device. The battery comprises a shell, an electrode assembly and an electrolyte. The shell is internally provided with an accommodating cavity, and the electrode assembly and the electrolyte are both arranged in the accommodating cavity. The electrode assembly comprises a positive electrode sheet, and 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 positive electrode active material having a chemical formula of Lix(NiaCobMnc)1-dMdO2-yAy. KEL of the battery satisfies 1.6 g / Ah≤KEL≤1.9 g / Ah, wherein KEL represents the ratio of the mass of a free electrolyte to the rated capacity of the battery, with the unit thereof being g / Ah. The space utilization rate η of the battery is greater than or equal to 0.8.

Description

Battery and power consuming device

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 2024104076959, filed on April 7, 2024, and entitled “Battery and power consuming device”, the contents of which are hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of battery, in particular to a battery and a power consuming device. BACKGROUND

[0004] The statements herein are provided only to enhance understanding of the present application and are not necessarily intended to constitute the prior art.

[0005] Energy density is one of the important indicators reflecting the performance of a battery. In order to improve the energy density of a battery, the traditional way tends to focus on the development of electrode active materials, by seeking high-gram-capacity active materials to improve the energy density of the battery. Among them, the positive electrode material with high nickel content has high gram capacity, which may be beneficial to improve the energy density of the battery. However, when the positive electrode material with high nickel content is applied to the battery, the energy density and cycle performance of the battery are difficult to effectively balance.

[0006] SUMMARY

[0007] The first aspect of the present application provides a battery, comprising a shell, an electrode assembly and an electrolyte; the shell has a containing cavity inside, the electrode assembly and the electrolyte are both arranged in the containing 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 positive electrode active material with a chemical formula of Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y , 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 comprises at least one of Al, Mg, Fe, Cu, V, Ti, Zr, W, Sb, Dy and Te, and A comprises at least one of P, S and halogen elements;

[0008] The K EL of the battery satisfies 1.6g / Ah≤K EL ≤1.9g / Ah, and the K ELrepresents the ratio of the mass of the free electrolyte to the rated capacity of the battery, in g / Ah;

[0009] The space utilization rate of the battery is ≥0.8, and the space utilization rate represents the ratio of the volume of the electrode assembly to the volume of the accommodating cavity.

[0010] In the above battery, by selecting a positive electrode material with a proper nickel content, and matching the positive electrode material with the K EL and the space utilization rate, the advantages of the capacity of the positive electrode material can be fully exerted, the battery has a high energy density, and the cycle performance of the battery is improved, so that the battery has a good cycle life, and the battery can have a high energy density and good cycle performance.

[0011] In some embodiments, 0.81≤η≤0.9. The space utilization rate in this range can make the battery have a relatively appropriate expansion space on the basis of considering a high energy density and good cycle performance, so as to reduce the risk of a large internal pressure of the battery during use.

[0012] In some embodiments, the electrode assembly further comprises a negative electrode tab, the negative electrode tab comprising 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 tab and the negative electrode tab better adapted, and reduce the risk of lithium precipitation of the negative electrode tab.

[0013] In some embodiments, the areal density of the negative electrode active layer is 0.12 g / 1540.25 mm 2 ~0.2 g / 1540.25 mm 2 . The areal density of the negative electrode active layer in this range can make the negative electrode tab have a high energy density, better adapt to the positive electrode tab, and better promote the exertion of the capacity of the positive electrode active material.

[0014] In some embodiments, the thickness of the negative electrode current collector is 4 μm~8 μm. The thickness of the negative electrode current collector in this range can make the negative electrode tab have good stability, and on the basis of maintaining a proper thickness of the negative electrode tab, promote the improvement of the thickness of the negative electrode active layer, and be conducive to further improving the energy density of the negative electrode tab.

[0015] 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. While maintaining a high energy density and a good cycle life, the thickness of the positive electrode current collector 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.

[0016] 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 enable the positive electrode active material to have a more appropriate usage amount, which is conducive to making the battery have a higher energy density.

[0017] In some embodiments, the compacted 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 charge and discharge, and thus improve the cycle life of the battery.

[0018] In some embodiments, the positive electrode active material comprises single crystal particles. Single crystal particles contain almost no grain boundaries, and are less likely to generate intergranular cracks during cycling. This can mitigate side reactions between the positive electrode plate and the electrolyte, thereby extending the cycle life of the battery.

[0019] In some embodiments, the single crystal particles include a first single crystal particle and a second single crystal particle, wherein the particle size of the first single crystal particle is smaller than the particle size of the second single crystal particle. By combining the first and second single crystal particles of different particle sizes, damage to the positive electrode current collector caused by the active material during compaction can be further reduced, further improving the cycling performance of the battery.

[0020] In some embodiments, the particle size ratio of the first single crystal particles to the second single crystal particles is (0.1-0.5): 1. Within this particle size ratio range, the first single crystal particles and the second single crystal particles 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.

[0021] In some embodiments, the positive electrode plate further comprises a primer layer; the primer layer is located between the positive electrode active layer and the positive electrode current collector, and the primer layer comprises a conductive agent. The primer layer can alleviate the damage of the active material to the positive electrode current collector during the compaction process, thereby improving the compaction density of the positive electrode active layer and further improving 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 cycle of the battery, which is beneficial to improve the cycle performance of the battery. On the other hand, the contact between the electrolyte and the positive electrode current collector can be reduced, so that the corrosion degree of the electrolyte to the positive electrode current collector can be reduced. The corrosion degree of the positive electrode current collector is reduced, which is beneficial to maintain a relatively stable structure of the positive electrode plate during the cycle of the battery, which is beneficial to improve the cycle performance of the battery.

[0022] In some embodiments, the thickness of the primer layer is 0.5 μm to 2 μm. Within this range, the primer layer can alleviate the damage to the positive electrode current collector and reduce the contact between the electrolyte and the positive electrode current collector, while maintaining a relatively appropriate thickness of the positive electrode plate, thereby maintaining a relatively appropriate volume of the battery.

[0023] In some embodiments, the mass percentage of the conductive agent in the primer layer is 40% to 60%. At this time, the conductive coating has good conductivity, which is beneficial to improve the conductivity of the positive electrode plate.

[0024] In some embodiments, the conductive agent comprises one or more of super-conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0025] In some embodiments, the electrolyte comprises a lithium salt, and the lithium salt comprises at least one of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, and lithium difluorophosphate. By selecting the lithium salt, the cycle life of the battery can be further improved.

[0026] 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.

[0027] In some embodiments, the electrolyte comprises an additive, and the additive comprises at least one of lithium bisfluorosulfonylimide, lithium difluorophosphate, and fluoroethylene carbonate. By selecting the additive, the cycle life of the battery can be further improved.

[0028] The second aspect of the present application provides a power utilization device. The power utilization device comprises the battery. BRIEF DESCRIPTION OF DRAWINGS

[0029] For a better description and illustration of the embodiments or examples provided by the present application, reference can be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the presently described embodiments or examples, and the best mode of these applications as presently understood. Moreover, the same reference numbers are used throughout the drawings to designate the same components. In the drawings:

[0030] FIG. 1 is a schematic view of a battery cell according to an embodiment of the present application.

[0031] FIG. 2 is an exploded view of the battery cell shown in FIG. 1 according to an embodiment of the present application.

[0032] FIG. 3 is a schematic view of an electric device using the battery as a power source according to an embodiment of the present application.

[0033] BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0034] For a better understanding of the present application, a more complete description of the application will be presented in the following with reference to the relevant drawings. The preferred embodiments of the present application are shown in the accompanying 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 disclosure of the present application more thorough and comprehensive.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0036] "ranges" disclosed herein can be defined, for example, by the lower and upper values. Any lower limit can independently be combined with any upper limit to define a range of any value. For example, if a range of 60-120 and 80-110 is listed, it is understood that a range of 60-110 and 80-120 is also contemplated. Furthermore, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is also listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, the use of "a" and "an" to describe a single item can be taken as equivalent to the use of "one" or "at least one," unless otherwise limited by context. In this application, the use of "or" as a conjunction can be taken as

[0037] In this application, the use of "a" and "an" to describe a single item can be taken as equivalent to the use of "one" or "at least one," unless otherwise limited by context. In this application, the use of "or" as a conjunction can be taken as

[0038] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, if not specifically stated.

[0039] Reference herein to "an embodiment" 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 that the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of other embodiments. It is explicitly understood that the embodiments described herein are combinable with each other. Reference herein to "an implementation" has a similar understanding.

[0040] Those skilled in the art can understand that the order of writing each step in the method of each embodiment or example 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 present application can be performed sequentially or randomly, and in some examples, sequentially. For example, the method includes steps (a) and (b), which means that the method can include sequentially performed steps (a) and (b), or sequentially performed steps (b) and (a). For example, the method also includes step (c), which means that step (c) can be added to the method in any order, for example, the method can include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0041] In the present application, A (such as B) means that B is one non-limiting example of A, and it can be understood that A is not limited to B.

[0042] In the present application, "optionally", "optional" and "optional" mean that it can or can not be present, that is, it means to select from any one of the two parallel schemes of "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.

[0043] An embodiment of the present application provides a battery, including a shell, an electrode assembly and an electrolyte. The shell has a containing cavity inside, and the electrode assembly and the electrolyte are arranged in the containing 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 contains a positive electrode active material with a chemical formula of Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y , wherein 0.2≤x≤1.2, 0.6≤a≤1, 0 EL 1.6g / Ah≤K EL ≤1.9g / Ah, and K ELThe ratio of the mass of the free electrolyte to the rated capacity of the battery, in units of gram / ampere-hour (g / Ah). The space utilization of the battery is η≥0.8, and the space utilization represents the ratio of the volume of the electrode assembly to the volume of the accommodation cavity.

[0044] In the battery of the embodiment, by selecting a positive electrode material with a proper nickel content, and adapting the K EL and the space utilization of the battery, the advantages of the high capacity of the positive electrode material can be fully played, so that the battery has a high energy density, and the cycle performance of the battery can be improved, so that the battery has a good cycle life, and the battery can have both a high energy density and a good cycle performance. For example, the energy density of the battery in an embodiment of the application can reach more than 280 watt-hours / kilogram (Wh / kg).

[0045] Further, generally, the positive electrode active material with a high nickel content has a low compaction density, and in order to obtain a high energy density, the thickness of the positive electrode active layer can be large, so that the expansion of the electrode sheet can be more obvious during charging and discharging, and thus the cycle life of the battery can be affected. In the embodiment, by adapting the K EL and the space utilization of the battery, the battery can have both a high energy density and a good cycle life.

[0046] It can be understood that the shell of the battery is generally square or cylindrical. The accommodation cavity of the square shell is correspondingly square. The accommodation cavity of the cylindrical shell is correspondingly cylindrical. When the shell of the battery is square, the space utilization η=(length of the electrode assembly / length of the accommodation cavity)×(width of the electrode assembly / width of the accommodation cavity). When the shell of the battery is cylindrical, the space utilization η=(diameter of the electrode assembly / diameter of the accommodation cavity)×(height of the electrode assembly / height of the accommodation cavity).

[0047] It can be understood that when the shell of the battery is square, the width of the electrode assembly and the width of the accommodation cavity respectively represent the width of the electrode assembly and the width of the accommodation cavity in the same direction. The length of the electrode assembly and the length of the accommodation cavity respectively represent the length of the electrode assembly and the length of the accommodation cavity in the same direction. Optionally, the direction of the width and the direction of the length are perpendicular.

[0048] Optionally, the free electrolyte in the application can be tested as follows: the battery is weighed, and the mass is recorded as m1. The battery is disassembled, and the electrolyte in the shell is removed. The electrode sheet is soaked in DMC for 16 hours (h), dried, and the mass of the shell and the electrode assembly is weighed, and the mass is recorded as m2. The mass of the free electrolyte is m1-m2, that is, the amount of the free electrolyte.

[0049] Optionally, the rated capacity of the battery in the present application can be tested by charging the battery at 0.33 Coulomb (C) to 4.25 volts (V) and then charging at constant voltage to a cutoff current of 0.05 C. Then discharge at 0.33 C to 2.8 V, and record the discharge capacity as the rated capacity of the battery.

[0050] In some embodiments, 0.81≤η≤0.9. The space utilization in this range can make the battery have a relatively appropriate expansion space inside the battery on the basis of giving consideration to higher energy density and better cycle performance, and reduce the risk of a relatively large internal pressure of the battery during use. Optionally, the space utilization 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 in the range constituted by any two of the above values.

[0051] It can be understood that when 0.6≤a≤1, the positive active material has a higher nickel content and a higher gram capacity, which is conducive to keeping the battery at a higher energy density. Optionally, a can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, and any value in the range constituted by any two of the above values. Further optionally, 0.8≤a≤1. Further optionally, Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y may 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.

[0052] 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 in the range constituted by any two of the above values.

[0053] 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 a range defined by any two of the above values.

[0054] 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 a range defined by any two of the above values.

[0055] 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 a range defined by any two of the above values. Optionally, 0≤d≤0.05.

[0056] 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 within a range defined by any two of the above values. Optionally, 0≤y≤0.05.

[0057] It can be understood that A includes at least one of P, S, and a halogen element, wherein the halogen element can be F, Cl, Br, etc.

[0058] Optionally, K of the battery EL may 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, and any value within a range defined by any two of the above values. Further optionally, 1.67 g / Ah≤K EL ≤1.85 g / Ah.

[0059] 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 formed by any two of the above values.

[0060] In some embodiments, the electrode assembly further comprises a negative electrode tab, the negative electrode tab comprising a negative current collector and a negative active layer on at least one surface of the negative current collector; wherein 1≤k≤1.15, k represents the ratio of the projected area of the negative active layer on the negative current collector to the projected area of the positive active layer on the positive current collector. k in this range can make the positive electrode tab and the negative electrode tab better adapted, reduce the risk of lithium precipitation in the negative electrode tab. 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 formed by any two of the above values.

[0061] In some embodiments, the areal density of the negative active layer is 0.12 g / 1540.25 mm 2 ~0.2 g / 1540.25 mm 2 , i.e. 0.12 g / 1540.25 mm 2 ≤ CW A ≤ 0.2 g / 1540.25 mm 2 . CW A In this range, the negative electrode tab can have a higher energy density, better adapt to the positive electrode tab, and better promote the capacity of the positive active material. CW A may be 0.12 g / 1540.25 mm 2 , 0.13 g / 1540.25 mm 2 , 0.14 g / 1540.25 mm 2 , 0.15 g / 1540.25 mm 2 , 0.16 g / 1540.25 mm 2 , 0.17 g / 1540.25 mm 2 , 0.18 g / 1540.25 mm 2 , 0.19 g / 1540.25 mm 2 , 0.2 g / 1540.25 mm 2 and any value within the range formed by any two of the above values.

[0062] In some embodiments, the thickness of the negative current collector is 4 micrometers (pm) to 8 pm. The thickness of the negative current collector in this range can make the negative electrode sheet have better stability, while on the basis of keeping the thickness of the negative electrode sheet appropriate, it can promote the increase of the thickness of the negative active layer, which is conducive to further improving the energy density of the negative electrode sheet. Optionally, the thickness of the negative current collector can be 4 pm, 5 pm, 6 pm, 7 pm, 8 pm, and any value in the range consisting of any two of the above values.

[0063] In some embodiments, the compaction density of the negative electrode sheet is 1.2 grams per cubic centimeter (g / cm 3 ) to 1.8 g / cm 3 . Optionally, the compaction density of the negative electrode sheet can be 1.2 g / cm 3 , 1.3 g / cm 3 , 1.4 g / cm 3 , 1.5 g / cm 3 , 1.6 g / cm 3 , 1.7 g / cm 3 , 1.8 g / cm 3 , and any value in the range consisting of any two of the above values.

[0064] In some embodiments, the thickness of the positive current collector is 9 pm to 15 pm. In this embodiment, the thickness of the positive current collector can be smaller. On the basis of keeping higher energy density and better cycle life, the smaller thickness of the positive current collector can reduce the weight of the battery on the one hand, and can increase the amount of positive active material on the other hand, further improving the energy density of the battery. Optionally, the thickness of the positive current collector is ≤13 pm. Optionally, the thickness of the positive current collector can be 9 pm, 10 pm, 11 pm, 12 pm, 13 pm, 14 pm, 15 pm, and any value in the range consisting of any two of the above values.

[0065] In some embodiments, the area density CW C of the positive active layer is 0.21 g / 15 40.25 mm 2 to 0.32 g / 15 40.25 mm 2 . The area density of the positive active layer in this range can make the positive active material have a more appropriate amount, which is conducive to making the battery have higher energy density. Optionally, the area density of the positive active layer can be 0.21 g / 15 40.25 mm 2 , 0.22 g / 15 40.25 mm 2 , 0.23 g / 15 40.25 mm 2 , 0.24 g / 15 40.25 mm 2 , 0.25 g / 15 40.25 mm2 0.26 g / 15 40.25 mm 2 0.27 g / 15 40.25 mm 2 0.28 g / 15 40.25 mm 2 0.29 g / 15 40.25 mm 2 0.3 g / 15 40.25 mm 2 0.31 g / 15 40.25 mm 2 and any value within a range derived from any two of the above values.

[0066] In some embodiments, the compacted density of the positive electrode tab is 3.2 g / cm 3 ~ 3.7 g / cm 3 . The compacted density of the positive electrode tab within this range can maintain a suitable thickness of the positive active layer on the basis of improving the energy density of the battery, reduce the adverse effects of material expansion on the cycle performance of the battery during charging and discharging, and thus improve the cycle life of the battery. Alternatively, the compacted density of the positive electrode tab can be 3.2 g / cm 3 , 3.3 g / cm 3 , 3.4 g / cm 3 , 3.5 g / cm 3 , 3.6 g / cm 3 , 3.7 g / cm 3 , etc. and any value within a range derived from any two of the above values.

[0067] Alternatively, in the present application, CW A can be tested as follows: a negative electrode tab is punched to obtain a small disc of 1540.25 square millimeters (mm 2 ), and the mass of the small disc is weighed. After removing the negative active layer and cleaning the negative current collector with NMP, the mass of the negative current collector is weighed. The mass of the small disc is subtracted from the mass of the negative current collector to obtain CW A . The thickness of the cleaned negative current collector is measured.

[0068] In the present application, CW C can be tested as follows: a positive electrode tab is punched to obtain a small disc of 1540.25 mm 2 , and the mass of the small disc is weighed. After removing the positive active layer and cleaning the positive current collector with NMP, the mass of the positive current collector is weighed. The mass of the small disc is subtracted from the mass of the positive current collector to obtain CW C . The thickness of the cleaned positive current collector is measured.

[0069] In some embodiments, the positive active material comprises single-crystal particles. The single-crystal particles have few grain boundaries, and the single-crystal particles are less likely to generate intergranular cracks during cycling, thus mitigating side reactions between the positive electrode plate and the electrolyte, thereby prolonging the cycle life of the battery. In addition, the single-crystal particles can effectively inhibit the irreversible phase transition of the material from the H2 crystal phase to the H3 crystal phase during charging and discharging, further improving the cycle performance of the battery.

[0070] In some embodiments, the single-crystal particles comprise 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 matching the first single-crystal particles and the second single-crystal particles with different particle sizes, the damage of the active material to the positive current collector during compaction can be further reduced, and the cycle performance of the battery can be further improved.

[0071] It can be understood that the size relationship between the particle size of the first single-crystal particles and the particle size of the second single-crystal particles can be tested by the following method: cutting a cross section along the thickness direction of the positive electrode plate, observing the cross section by a scanning electron microscope (SEM), and then obtaining the size relationship between the particle size of the first single-crystal particles and the particle size of the second single-crystal particles.

[0072] Optionally, the particle size ratio of the first single-crystal particles to the second single-crystal particles is (0.1-0.5):1. Within this particle size ratio range, the first single-crystal particles and the second single-crystal particles better match, which is conducive to improving the compaction density of the positive electrode plate and further promoting the improvement of the energy density of the battery. Optionally, the particle size ratio of the first single-crystal particles to the second single-crystal particles can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, and any value within the range formed by any two of the above values.

[0073] In some embodiments, the positive electrode plate further comprises a primer layer. The primer layer is located between the positive active layer and the positive current collector, and the primer layer comprises a conductive agent. The primer layer is arranged on one hand, which can mitigate the damage of the active material to the positive current collector during compaction, thereby improving the compaction density of the positive active layer and further improving the energy density of the battery. At the same time, the damage of the positive current collector is reduced, which can make the positive electrode plate maintain a relatively stable structure during the cycle of the battery, which is conducive to improving the cycle performance of the battery. On the other hand, it can reduce the contact between the electrolyte and the positive current collector, which can reduce the corrosion degree of the electrolyte to the positive current collector. The corrosion degree of the positive current collector is reduced, which is conducive to making the positive electrode plate maintain a relatively stable structure during the cycle of the battery, which is conducive to improving the cycle performance of the battery. It can be understood that the primer layer can be prepared by a gravure process.

[0074] Optionally, the thickness of the undercoat layer is 0.5 μm to 2 μm. The thickness of the undercoat layer in this range can keep the positive electrode sheet at a proper thickness on the basis of mitigating damage to the positive electrode current collector and reducing contact of the electrolyte with the positive electrode current collector, and thus keep the battery at a proper volume. For example, the thickness of the undercoat 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 in a range defined by any two of the above values.

[0075] Optionally, the conductive agent accounts for 40% to 60% of the mass percentage of the undercoat layer. In this case, the conductive coating has good conductivity, which is conducive to improving the conductivity of the positive electrode sheet. Optionally, the conductive agent can account for 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60% of the mass percentage of the undercoat layer, and any value in a range defined by any two of the above values.

[0076] Optionally, the conductive agent includes one or more of super-conductive carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0077] In some embodiments, the undercoat layer further includes a binder, which is conducive to improving the adhesion between the positive electrode active layer and the positive electrode current collector. Optionally, the binder includes polyacrylate.

[0078] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, and lithium difluorophosphate. The selection of the lithium salt can further improve the cycle life of the battery. 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 in 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 in a range defined by any two of the above values.

[0079] In some embodiments, the electrolyte includes an additive, and the additive includes at least one of lithium bisfluorosulfonylimide, lithium difluorophosphate, and fluoroethylene carbonate. The selection of the additive is conducive to further improving the cycle life of the battery.

[0080] The application also provides a battery in another embodiment.

[0081] The battery and the electric device of the application are described below with reference to the accompanying drawings.

[0082] Generally, a battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During charging and discharging of the battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, and functions to prevent short circuiting between the positive electrode and the negative electrode, while allowing ions to pass through.

[0083] The positive electrode sheet

[0084] 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, the positive electrode active layer including a positive electrode active material.

[0085] As a non-limiting example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode active material layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0086] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. 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 material. Non-limiting examples of the metal material in the positive electrode current collector 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. Non-limiting examples of the polymer material base material in the positive electrode current collector 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.

[0087] In some embodiments, the positive electrode active layer may also optionally include a positive electrode active material for a battery that is well 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. 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 oxide may include LiCoO2; non-limiting examples of lithium nickel oxide may include LiNiO2; non-limiting examples of lithium manganese oxide may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxide 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 0.1 Mn 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.

[0088] In some embodiments, Li x (Ni a Co b Mn c ) 1-d M d O 2-y A ya mass percentage of the positive electrode active material in the positive electrode active layer is 90% to 100%.

[0089] In some embodiments, the positive electrode active 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.

[0090] In some embodiments, the positive electrode active 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.

[0091] 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-methylpyrrolidone (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 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% by weight (wt%) to 80 wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 milliPascal-seconds (mPa-s) to 25000 mPa-s.

[0092] Negative electrode tab

[0093] The negative electrode tab includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector, the negative electrode active layer including a negative electrode active material.

[0094] 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.

[0095] 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.

[0096] 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 only one kind, or two or more kinds can be combined.

[0097] In some embodiments, the negative active layer can also 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).

[0098] In some embodiments, the negative active layer can also 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.

[0099] In some embodiments, the negative active layer can also optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

[0100] 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 one 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.

[0101] Electrolyte

[0102] 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.

[0103] In some embodiments, the electrolyte employs an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0104] 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).

[0105] In some embodiments, the solvent can include one or more of 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 , fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, methyl ethyl sulfone, and diethyl sulfone.

[0106] In some embodiments, the electrolyte can optionally further include 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 capable of improving certain performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature or low-temperature performance of the battery, etc.

[0107] In some embodiments, the additive in the electrolyte can include, but is not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), etc.

[0108] Separator film

[0109] In some embodiments, a separator film is further included in the battery. 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.

[0110] 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 respective layers can be the same or different, and are not particularly limited.

[0111] In some embodiments, the thickness of the separator film is 6 μm to 40 μm, and can be optionally 12 μm to 20 μm.

[0112] 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.

[0113] In some embodiments, the battery can include an outer package. The outer package can be used to package the electrode assembly and the electrolyte described above.

[0114] In some embodiments, the outer package of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery can also be a soft package, such as a pouch-type 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, etc.

[0115] The battery includes at least one battery cell. The battery can include one or more battery cells.

[0116] In the present application, a "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. During the charging and discharging of the battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct the active ions between the positive electrode sheet and the negative electrode sheet.

[0117] 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 1 of a square structure as an example. It can be understood that a cylindrical battery cell includes a cylindrical housing having a cylindrical accommodation cavity inside. A square battery cell includes a square housing having a square accommodation cavity inside.

[0118] In some embodiments, referring to FIG. 2, the outer package can include a housing 11 and a cover plate 13. Among them, the housing 11 can include a bottom plate and a side plate connected to the bottom plate, which enclose to form an accommodation cavity. The housing 11 has an opening communicating with the accommodation cavity, and the cover plate 13 can be provided on the opening to close the accommodation cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form an electrode assembly 12 through a winding process or a stacking process. The electrode assembly 12 is packaged in the accommodation cavity. The electrolyte is impregnated in the electrode assembly 12. The number of electrode assemblies 12 contained in the battery cell 1 can be one or more, which can be selected by those skilled in the art according to actual needs.

[0119] The battery can be a battery module or a battery pack.

[0120] The battery module includes at least one battery cell. The number of battery cells contained in the battery module can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0121] In the battery module, the plurality of battery cells can be arranged in sequence along the length direction of the battery module. Of course, they can also be arranged in any other way. Further, the plurality of battery cells can be fixed by fasteners.

[0122] Optionally, the battery module can further include a housing having an accommodation space, and the plurality of battery cells are accommodated in the accommodation space.

[0123] 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, which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0124] A battery pack can include a battery case and a plurality of battery modules disposed in the battery case. The battery case includes an upper case and a lower case, and the upper case is capable of being disposed on the lower case and forms an enclosed space for accommodating the battery modules. The plurality of battery modules can be arranged in the battery case in any manner.

[0125] In addition, the application also provides a power utilization device, which comprises the battery provided by the application. The 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.

[0126] As the power utilization device, the battery can be selected according to the use requirement thereof.

[0127] FIG. 3 is a power utilization device 2 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 requirement of high power and high energy density of the battery for the power utilization device, a battery pack or a battery module can be used.

[0128] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinness, and a battery can be used as a power supply.

[0129] In order to make the technical problems, technical solutions and beneficial effects solved by the application clearer, the application will be further described in detail below in combination with embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. The description of the at least one exemplary embodiment below is actually only illustrative, but not as any limitation on the application and its application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0130] Unless specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in the art or according to the product instructions are used. Unless the manufacturer of the reagent or instrument is specified, it is a conventional product that can be obtained by market purchase.

[0131] Embodiment 1

[0132] In this embodiment, the positive active material is LiNi 0.6 Co 0.2 Mn 0.2 O2.

[0133] (1) Preparation of the positive electrode sheet.

[0134] The positive electrode active material, the binder polyvinylidene fluoride, and the conductive agent acetylene black were mixed in a weight ratio of 98:1:1, N-methylpyrrolidone was added as a solvent, and the slurry was stirred under vacuum until uniform to obtain a positive electrode slurry. The positive electrode slurry was coated on an aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet.

[0135] (2) Preparation of the negative electrode sheet.

[0136] The graphite, the binder styrene-butadiene rubber, and the conductive agent acetylene black were mixed by stirring at a rotational speed of 800 revolutions per second (r / s), and then subjected to wetting, kneading, and dispersion treatment to obtain a negative electrode slurry. The negative electrode slurry was coated on a copper foil, dried, and cold-pressed to obtain a negative electrode sheet.

[0137] (3) Preparation of the electrolyte.

[0138] In an argon atmosphere glove box (H2O < 0.1 parts per million (ppm), O2 < 0.1 ppm), organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:7, 12.5% by weight (based on the total weight of the ethylene carbonate and ethyl methyl carbonate solvents) LiPF6 was dissolved in the above organic solvents, and stirred until uniform to obtain an electrolyte.

[0139] (4) The separator film was a PP-PE copolymer microporous film with a thickness of 7 μm and an average pore size of 80 nanometers (nm) that was commercially available.

[0140] (5) The negative electrode sheet, the separator film, and the positive electrode sheet were stacked in order and wound to obtain a wound cell. The cell was placed in an outer packaging square aluminum shell, dried, and then injected with the electrolyte. After being packaged, allowed to stand, subjected to formation, aging, secondary packaging, and capacity processes, a battery was obtained.

[0141] Examples 2-11 and Comparative Examples 1-3

[0142] Examples 2-11 and Comparative Examples 1-3 differ from Example 1 in that 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 sheet A , the areal density CW of the positive electrode active layer C , the areal density CW of the negative electrode active layer A , and the K of the battery ELThe space utilization rate of the battery, η, the ratio k of the projected area of the negative active layer on the negative current collector to the projected area of the positive active layer on the positive current collector, is different, and is specifically shown in Table 1. Among them, the battery in Example 4 adopts a stacking process to obtain a stacked battery. When the positive active material comprises a first single crystal and a second single crystal, in the corresponding examples, the first single crystal and the second single crystal differ in particle size.

[0143] Test Example

[0144] (1) Battery energy density test.

[0145] The test method is: charging the battery monomer at 0.33C constant current to 4.25V, and then constant voltage charging to the cutoff current 0.05C; then discharging the battery monomer at 0.33C constant current to 2.8V, and recording the discharge energy (unit: Wh). The mass of the battery monomer (unit: kg) is weighed, and the energy density per unit mass of the battery monomer is calculated from the discharge energy / mass, and the unit is Wh / kg. The test results are shown in Table 1.

[0146] (2) Battery cycle performance test.

[0147] The test method is: testing the capacity before the battery cycle; 0.5C constant current charging to 97% SOC, and the cutoff voltage is 4.17V, 4.17V constant voltage charging to 0.05C; 0.5C discharging to 5% SOC, and the cutoff voltage is 3.33V; repeating 100 cycles, testing the capacity after the battery cycle, and calculating the cycle retention rate after 100 cycles. When the capacity retention rate deviates significantly from the normal downward trend during the cycle process, it is considered that the cycle has dived.

[0148] Table 1

[0149] In Table 1, in the particle composition column, "first single crystal" indicates that the particle composition of the positive active material is first single crystal particles. "First: second" indicates that the particle composition of the positive active material is first single crystal particles and second single crystal particles mixed according to the corresponding particle size ratio. PD C represents the compaction density of the positive electrode plate, and the unit is g / cm 3 . PD A represents the compaction density of the negative electrode plate, and the unit is g / cm 3 . CW C represents the area density of the positive active layer, and the unit is g / 1540.25mm 2 . CW A represents the area density of the negative active layer, and the unit is g / 1540.25mm 2 . K ELThe unit of g / Ah. η represents the space utilization of the battery. k represents the ratio of the projected area of the negative active layer on the negative current collector to the projected area of the positive active layer on the positive current collector. The energy density represents the unit mass energy density of the battery cell, and the unit is Wh / kg. The capacity retention rate represents the capacity retention rate after the battery is cycled for 100 cycles, and the unit is %. Whether the battery is diving during the cycling process, wherein "no" represents no diving, and "yes" represents diving.

[0150] As can be seen from Table 1, by comparing the examples and the comparative examples, it can be seen that the batteries in the examples have higher energy density, indicating that when the nickel content of the positive active material is higher, when the K EL and the space utilization satisfies 1.6 g / Ah≤K EL ≤1.9 g / Ah, η≥0.8, higher energy density can be exhibited.

[0151] The technical features of the above-described examples can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above-described examples are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present disclosure.

[0152] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A battery comprising a housing, an electrode assembly, and an electrolyte; the housing has a receiving cavity, the electrode assembly and the electrolyte are both disposed 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; The battery K EL Meet 1.6g / Ah≤K EL ≤1.9g / Ah, the 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 ratio η of the battery is greater than or equal to 0.8, where the space utilization ratio represents a ratio of the volume of the electrode assembly to the volume of the accommodating cavity.

2. The battery according to claim 1, wherein The electrode assembly also includes a negative electrode plate, which includes 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.

3. The battery according to claim 2, wherein The surface density of the negative electrode active layer is 0.12g / 1540.25mm 2 ~0.2g / 1540.25mm 2 .

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

5. The battery according to any one of claims 1 to 4, wherein 0.81≤η≤0.

9.

6. The battery according to any one of claims 1 to 5, wherein The thickness of the positive electrode current collector is 9 μm to 15 μm.

7. The battery according to any one of claims 1 to 6, wherein The surface density of the positive electrode active layer is 0.21g / 1540.25mm 2 ~0.32g / 1540.25mm 2 .

8. The battery according to any one of claims 1 to 7, wherein The compaction density of the positive electrode sheet is 3.2 g / cm 3 ~3.7g / cm 3 .

9. The battery according to any one of claims 1 to 8, wherein The positive active material includes single crystal particles.

10. The battery according to claim 9, wherein 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.

11. The battery according to claim 10, wherein The particle size ratio of the first single crystal particles to the second single crystal particles is (0.1-0.5):

1.

12. The battery according to any one of claims 1 to 11, wherein 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.

13. The battery according to claim 12, wherein The thickness of the primer layer is 0.5 μm to 2 μm.

14. The battery according to claim 12 or 13, wherein The mass percentage of the conductive agent in the primer layer is 40% to 60%.

15. The battery according to any one of claims 12 to 14, wherein The conductive agent includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

16. The battery according to any one of claims 1 to 15, wherein The electrolyte includes a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium difluorobis(oxaloyl)phosphate.

17. The battery according to claim 16, wherein The molar concentration of the lithium salt in the electrolyte is 1.1 mol / L to 1.5 mol / L.

18. The battery according to any one of claims 1 to 17, wherein The electrolyte includes an additive, and the additive includes at least one of lithium bis(fluorosulfonyl)imide, lithium difluorobis(oxaloyl)phosphate, and fluoroethylene carbonate.

19. An electrical device comprising the battery according to any one of claims 1 to 18.

Images