Battery and power consuming device

Abstract

The application relates to a battery and a power utilization device, and belongs to the technical field of batteries. The application takes the direction in which the positive pole piece leads out the positive pole lug as a first direction, and through control of the ratio of the size of the insulating layer in the first direction / the size of the positive pole piece in the first direction and the concave-convex degree of the surface of the positive active material layer away from the positive pole current collector, a specific relationship can be met, the connectivity between the positive pole piece and the diaphragm can be ensured to be appropriate, lithium ions are easy to transmit between the positive pole piece and the diaphragm, lower interface impedance is realized, the first charge-discharge efficiency of the battery is improved, after circulation, the close fit can be avoided, the electrolyte impregnation effect is optimized, the lithium ion transmission efficiency is improved, and the battery kinetic performance is enhanced, so that excellent and balanced first coulomb efficiency and kinetic performance can be realized.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more particularly to a battery and an electrical device. Background Technology

[0002] Lithium-ion batteries have been widely used due to their outstanding advantages such as high operating voltage, long cycle life, no memory effect, low self-discharge rate, and environmental friendliness. However, for newly manufactured lithium-ion batteries, the adhesion between the separator and the positive electrode is poor, which is not conducive to the transport of lithium ions between the positive electrode and the separator, resulting in increased interfacial impedance and low initial coulombic efficiency of the battery. Summary of the Invention

[0003] The purpose of this application is to overcome the shortcomings of the prior art and provide a battery and an electrical device that enable the battery to have both excellent initial coulombic efficiency and kinetic performance.

[0004] To achieve the above objectives, in a first aspect, this application provides a battery, including a cell, wherein the cell includes a positive electrode plate and a positive electrode tab;

[0005] The positive electrode plate is connected to the positive electrode tab, with the direction in which the positive electrode plate leads out of the positive electrode tab being the first direction;

[0006] The positive electrode sheet includes a positive current collector, a positive active material layer, and an insulating layer. The positive current collector includes a first region close to the positive electrode tab and a second region away from the positive electrode tab. An insulating layer is provided on at least one surface of the first region, and a positive active material layer is provided on at least one surface of the second region.

[0007] The battery satisfies: 0.014 ≤ b × c ≤ 30.

[0008] Wherein, b% = (dimension of the insulating layer in the first direction / dimension of the positive electrode sheet in the first direction) × 100%;

[0009] c μm refers to the unevenness of the surface of the positive electrode active material layer on the side away from the positive electrode current collector.

[0010] Secondly, this application provides an electrical device including the battery.

[0011] Compared to existing technologies, the beneficial effects of this application include: taking the direction in which the positive electrode tab is led out of the positive electrode sheet as the first direction, by controlling the ratio of the size of the insulating layer in the first direction to the size of the positive electrode sheet in the first direction and the unevenness of the surface of the positive electrode active material layer away from the positive electrode current collector to satisfy a specific relationship, it can ensure that the connection between the positive electrode sheet and the separator is appropriate. Not only can lithium ions be easily transported between the positive electrode sheet and the separator, achieving a lower interface impedance and improving the first charge and discharge efficiency of the battery, but it can also avoid excessively tight adhesion after cycling, optimize the electrolyte wetting effect, improve lithium ion transport efficiency, and enhance battery kinetic performance, thereby achieving excellent and balanced first coulombic efficiency and kinetic performance. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing the distribution of the insulating layer on the positive electrode sheet and the tab in one embodiment of this application. 1-Positive electrode active material layer, 2-Insulating layer, 3-Positive electrode tab;

[0013] Figure 2 This is a schematic diagram showing the distribution of the insulating layer on the positive electrode sheet and the tab in another embodiment of this application. 31 - Positive electrode active material layer, 32 - Insulating layer, 33 - Positive electrode tab. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0015] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0016] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0017] In this application, there are no particular restrictions on the specific dispersion and mixing methods.

[0018] Unless otherwise specified, all reagents or instruments used in this application are commercially available products.

[0019] In this application, the tab is defined as follows: the tab is disposed on one side of the positive / negative current collector and is separately / integrated with the current collector, and is electrically connected to the current collector to conduct the current on the corresponding current collector;

[0020] Material / Composition of the tabs: They are made of highly conductive metallic materials (such as aluminum, aluminum alloys, copper, or nickel). The positive tab is generally made of aluminum or aluminum alloy.

[0021] In this application, the insulating layer is defined as follows: coated on at least one side of the current collector near the tab, and coated on at least one side of the tab surface, to prevent short circuit between the tab and the opposite electrode; it can also make the tab less prone to breakage when the battery cell is assembled by bending.

[0022] The insulation layer is made of at least one of the following materials: PVDF (polyvinylidene fluoride), polyacrylic acid, boehmite, polypropylene, polyethylene, etc.

[0023] Battery

[0024] According to a first aspect of this application, a battery is provided, including a cell, the cell including a positive electrode plate and a positive electrode tab;

[0025] The positive electrode plate is connected to the positive electrode tab, with the direction in which the positive electrode plate leads out of the positive electrode tab being the first direction;

[0026] The positive electrode sheet includes a positive current collector, a positive active material layer, and an insulating layer. The positive current collector includes a first region close to the positive electrode tab and a second region away from the positive electrode tab. An insulating layer is provided on at least one surface of the first region, and a positive active material layer is provided on at least one surface of the second region.

[0027] The battery satisfies: 0.014 ≤ b × c ≤ 30.

[0028] Wherein, b% = (dimension of the insulating layer in the first direction / dimension of the positive electrode sheet in the first direction) × 100%;

[0029] c μm represents the unevenness of the surface of the positive electrode active material layer on the side away from the positive electrode current collector.

[0030] The initial charge-discharge efficiency of the battery is relatively low, and the charging capacity and discharging capacity are mismatched. The inventors discovered that, on the one hand, the bonding reliability between the separator and the positive and negative electrodes is poor after battery fabrication, resulting in poor interfacial contact between the separator and the electrodes, hindering lithium-ion transport and thus leading to low initial charge-discharge efficiency. On the other hand, during charging, as lithium ions are inserted and extracted, the electrodes expand and contract, especially the nickel-cobalt-manganese positive electrode (which experiences a significant "breathing effect" during charge and discharge), subjecting the separator to stress impact and increasing the risk of separation between the separator and the electrodes. The aforementioned insulating layer not only insulates the positive and negative electrodes, preventing internal short circuits, but also acts as a buffer layer, absorbing the expansion of the positive electrode, absorbing the stress generated by the positive electrode and separator, reducing impact stress on the separator, improving the connection between the separator and the positive electrode, and increasing the lithium-ion transport rate between the positive electrode and the separator.

[0031] The unevenness of the surface of the positive electrode active material layer on the side away from the positive electrode current collector reflects the surface roughness, which affects the reliability of the connection between the positive electrode and the separator. Appropriate unevenness can improve the connection strength between the separator and the positive electrode, preventing a weak connection that would hinder lithium-ion transport, reduce the battery's initial efficiency, and consequently affect its cycle performance. However, excessive unevenness can also cause the separator and electrode to adhere too tightly, hindering electrolyte wetting and thus affecting the battery's fast-charging performance.

[0032] By controlling the product of b and c within the aforementioned specific range, a suitable and reliable connection between the positive electrode and the separator can be ensured, which is beneficial for the transport of lithium ions between the positive electrode and the separator, achieving a lower interface impedance, improving the first charge and discharge efficiency of the battery, while avoiding excessively tight bonding after subsequent cycles, optimizing the electrolyte wetting effect, improving lithium ion transport efficiency, and enhancing battery kinetic performance, thereby achieving excellent and balanced first coulombic efficiency and kinetic performance.

[0033] For example, b×c can be 0.014, 0.03, 0.05, 0.07, 0.1, 0.3, 0.5, 0.7, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 14.5, 14.9, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, or any range formed by two of the above values. In some embodiments, b and c satisfy: 0.05 ≤ b×c ≤ 10, to make the connection between the positive electrode and the separator more suitable, thereby making the initial coulombic efficiency and kinetic performance of the battery more balanced.

[0034] In some embodiments, the range of b% is 0.2% to 10%. For example, b% is a range formed by any two values ​​of 0.2%, 0.3%, 0.5%, 0.7%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or more. In one embodiment, the range of b% is 0.4% to 6%.

[0035] When b% is in the range of 0.2% to 10%, especially in the range of 0.4% to 6%, it can, on the one hand, improve the buffering capacity of the insulating layer for the positive electrode, improve the connection between the positive electrode and the separator, and facilitate the transport of lithium ions between the positive electrode and the separator. On the other hand, it ensures that the size of the positive electrode current collector or other positions of the tab (such as the metal strip) is appropriate, improves the electrical connection performance of the tab, and thus improves the overcurrent capacity of the tab, thereby making the initial coulombic efficiency and kinetic performance of the battery more balanced.

[0036] The b-value can be controlled by adjusting at least one of the following process parameters: the solid content and / or extrusion rate of the tab adhesive, and the gasket opening width of the tab adhesive extrusion equipment.

[0037] This application does not limit the method for detecting the b-value; those skilled in the art can perform the detection using conventional techniques. For example, the b-value can be detected using the following method:

[0038] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the connected positive electrode plate and positive electrode tab. Place the connected positive electrode plate and positive electrode tab in DMC (dimethyl carbonate) and immerse them at room temperature (25℃, the same below) for 60 minutes. Take them out and air dry them at room temperature with humidity ≤15%.

[0039] In the insulation layer area, select 5 locations at equal intervals, and use a ruler (such as a ten-thousand-point caliper) to measure the size of the insulation layer area in the first direction at these 5 locations. Calculate the average value to obtain the size of the insulation layer in the first direction.

[0040] Five positions are randomly selected in the first direction of the positive electrode. The width of the electrode at these five positions (i.e., the dimension in the first direction) is measured using a ruler (such as a ten-thousand-point caliper). The average value is then used to obtain the dimension of the positive electrode in the first direction.

[0041] The value of b is calculated using the following formula: b% = (Dimension of the insulating layer in the first direction / Dimension of the positive electrode in the first direction) × 100, where the dimensions of the insulating layer in the first direction and the dimensions of the positive electrode in the first direction are in the same unit, for example, mm.

[0042] In some embodiments, the range of c μm is 0.05~3.5 μm. For example, c μm is a range formed by any two of the following values: 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.7 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.5 μm. In some embodiments, the range of c μm is 0.1~2.5 μm.

[0043] When the c μm is in the range of 0.05 μm to 3.5 μm, especially in the range of 0.1 to 2.5 μm, it can improve the connection between the positive electrode and the separator, which is beneficial to the transport of lithium ions between the positive electrode and the separator. On the other hand, during cycling, lithium salts (such as LiF and Li2CO3) and organic polymers produced by electrolyte decomposition are deposited and grown at the microscopic contact points between the positive electrode and the separator. These substances themselves have a certain degree of viscosity, or like cement, "bond" the porous surfaces of the positive electrode and the separator together, resulting in an overly tight connection between the separator and the positive electrode after cycling, which hinders electrolyte wetting. Controlling the c value within the above range can avoid the overly tight connection between the separator and the positive electrode after cycling, which would cause difficulties in electrolyte wetting and hinder ion transport, thereby making the initial coulombic efficiency and kinetic performance of the battery more balanced.

[0044] The c-value can be controlled by adjusting at least one of the following process parameters: average particle size and / or polycrystalline / single crystal distribution of the cathode material (i.e., the cathode active material layer, the same below), binder content in the cathode slurry, coating speed of the cathode slurry, rolling pressure, etc.

[0045] This application does not limit the method for detecting the c-value; those skilled in the art can perform the detection using conventional techniques. For example, the c-value can be detected using the following method:

[0046] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the positive electrode. Place the positive electrode in DMC (dimethyl carbonate) and immerse it at room temperature (25℃, the same below) for 60 minutes. Take it out and air dry it at room temperature.

[0047] The positive electrode sheet is placed on a smooth glass plate and its four corners are fixed. The roughness of the surface of the positive electrode active material layer away from the positive electrode current collector is measured by sampling points using a roughness instrument (such as the Mitutoyo SJ210 of Japan). Six points are taken, and the average roughness of these six points is calculated to obtain the degree of unevenness of the surface of the positive electrode active material layer away from the positive electrode current collector.

[0048] In some embodiments, the size of the insulating layer in the first direction is in the range of 2 to 10 mm, such as 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or any two of the above values ​​forming a range.

[0049] In some embodiments, the size of the insulating layer in the first direction ranges from 4 to 7 mm.

[0050] Controlling the size of the insulating layer in the first direction to be within the range of 2 to 10 mm, especially within the range of 4 to 7 mm, is beneficial for improving its buffering effect on electrode expansion, improving the connection between the separator and the positive electrode, increasing the lithium ion transport rate between the positive electrode and the separator, improving the electrical connection performance of the tab, and improving the overcurrent capacity of the tab, thereby making the battery's initial coulombic efficiency and kinetic performance more balanced.

[0051] In some embodiments, the size range of the positive electrode in the first direction is 50~1100mm, such as 50mm, 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm, 1100mm or any two of the above values.

[0052] In some embodiments, the positive electrode tab and the positive current collector are integrated.

[0053] In some embodiments, the thickness of the insulating layer ranges from 10 to 100 μm, which is beneficial for improving the buffering effect against electrode expansion, improving the connection between the separator and the positive electrode, and increasing the lithium-ion transport rate between the positive electrode and the separator. For example, the thickness of the insulating layer is within the range of any two values ​​of 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or more. The thickness direction of the insulating layer is consistent with the thickness direction of the positive electrode active material layer. In some embodiments, the insulating layer is located on both sides of the positive electrode current collector.

[0054] The thickness of the insulation layer can be controlled by adjusting the solid content and / or extrusion amount of the tab adhesive, the coating of the tab adhesive, and other methods, such as the coating rate.

[0055] The method for detecting the thickness of the insulating layer is not limited in this application, and those skilled in the art can perform the detection using conventional techniques. For example, the thickness of the insulating layer can be detected using the following method:

[0056] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the connected positive electrode plate and positive electrode tab. Place the connected positive electrode plate and positive electrode tab in DMC (dimethyl carbonate) and immerse them at room temperature (25℃, the same below) for 60 minutes. Take them out and air dry them at room temperature.

[0057] In the insulation layer area, select 5 locations at equal intervals, measure the insulation layer height at these 5 locations using a ruler (such as a ten-thousand-point ruler), and calculate the average value to obtain the insulation layer thickness.

[0058] In some embodiments, the insulating layer comprises an organic compound, including at least one selected from polyvinylidene fluoride (PVDF) and polyacrylic acid (PAA). The organic compounds such as PVDF and PAA added to the insulating layer possess viscoelasticity and flexibility, which can enhance the cushioning capacity of the tab adhesive.

[0059] In some embodiments, the insulating layer comprises an inorganic compound, including at least one selected from aluminum oxide, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite. Adding inorganic compounds such as aluminum oxide, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite to the insulating layer can improve its structural strength and reduce the risk of separation between the insulating layer and the current collector after expansion.

[0060] In some embodiments, the mass ratio of organic compound to inorganic compound in the insulating layer is (10-50):(50-90), such as 10:90, 20:80, 30:70, 40:60, 50:50 or any two of the above values ​​forming a range.

[0061] In some embodiments, the first region does not have a positive electrode active material layer, and the insulating layer is located in the first region.

[0062] In some embodiments, parallel to the positive electrode lead-out direction, the insulating layer extends into the second region and partially overlaps with the positive electrode active material layer. The size of the overlapping area between the insulating layer and the positive electrode active material layer in the first direction ranges from 0.1 to 0.5 mm, such as 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, or any two of these values. Controlling the size of the overlapping area between the insulating layer and the positive electrode active material layer in the first direction within the above range improves lithium-ion insertion / extraction, enhancing initial coulombic efficiency and fast-charging performance.

[0063] The method for detecting the size of the overlapping area between the insulating layer and the positive electrode active material layer in the first direction is not limited in this application, and those skilled in the art can perform the detection using conventional techniques. For example, the size of the overlapping area between the insulating layer and the positive electrode active material layer in the first direction can be detected using the following method:

[0064] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the connected positive electrode plate and positive electrode tab. Place the connected positive electrode plate and positive electrode tab in DMC (dimethyl carbonate) and immerse them at room temperature (25℃, the same below) for 60 minutes. Take them out and air dry them at room temperature.

[0065] In the overlapping area of ​​the insulating layer and the positive electrode active material layer, select 5 locations and use a ruler (such as a ten-thousand-point caliper) to measure the size of the overlapping area in the first direction at these 5 locations. Calculate the average value to obtain the size of the overlapping area of ​​the insulating layer and the positive electrode active material layer in the first direction.

[0066] In some embodiments, a portion of the insulating layer is located on the surface of the positive electrode active material layer away from the positive electrode current collector.

[0067] In some embodiments, the insulating layer covers a portion of the positive electrode tab, and the area covered by the insulating layer on the positive electrode tab has a size ranging from 0.5 to 4 mm in the first direction to improve the current-carrying capacity of the electrode tab. For example, the width of the area covered by the insulating layer on the electrode tab in the first direction is within the range formed by any two of the following values: 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or more.

[0068] The method for detecting the size of the area covered by the insulating layer on the positive electrode tab in the first direction is not limited in this application, and those skilled in the art can perform the detection using conventional technical means. For example, the size of the area covered by the insulating layer on the positive electrode tab in the first direction can be detected using the following method:

[0069] The battery is discharged at 0.33C to the lower limit voltage of 2.5V to obtain a discharged battery. The discharged battery is disassembled to obtain the connected positive electrode plate and positive electrode tab. The connected positive electrode plate and positive electrode tab are placed in DMC (dimethyl carbonate) and soaked at room temperature (25°C, the same below) for 60 minutes, taken out, and dried at room temperature;

[0070] In the region where the insulating layer covers the electrode tab, randomly select 5 positions, use a ruler (such as a micrometer) to measure the corresponding dimensions of these 5 positions, and calculate the average value to obtain the dimension of the covering area of the insulating layer on the positive electrode tab in the first direction.

[0071] In some embodiments, the nickel-cobalt-manganese material includes lithium nickel cobalt manganese oxide, and the chemical formula of the lithium nickel cobalt manganese oxide is Li a Ni x Co y Mn 1-x-y O2, where the range of a is 0.9 - 1.1, 0 < x < 1; 0 < y < 1; x + y < 1. For example, a is 0.9, 1, 1.1 or the range formed by any two of the above values; x is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95 or the range formed by any two of the above values; y is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.35 or the range formed by any two of the above values; x + y is 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95 or the range formed by any two of the above values.

[0072] In some embodiments, the lithium nickel cobalt manganese oxide further contains element M, and element M is selected from at least one of Zr, Mo, B, Al, W, Sr, Mg, Ca, Ta, Ti, Nb, Y, Ta, Sb.

[0073] Element M can be included in the lithium nickel cobalt manganese oxide in the form of doping, in the form of coating, or in the form of coexistence of the above two forms. The present application does not limit the content of element M in the lithium nickel cobalt manganese oxide. In some embodiments, the mass content of element M in the lithium nickel cobalt manganese oxide is selected to be 100 - 20000 ppm, such as 100 ppm, 500 ppm, 1000 ppm, 5000 ppm, 10000 ppm, 12000 ppm, 15000 ppm, 17000 ppm, 20000 ppm or the range formed by any two of the above values.

[0074] The lithium nickel cobalt manganese oxide may be free of coating material or coated with coating material on part or all of its surface, such as coating material containing element M on part or all of its surface. In some embodiments, the surface of the lithium nickel cobalt manganese oxide particles is coated with coating material, which includes at least one of the following: tungsten oxide, boron oxide, and aluminum oxide. In one embodiment, the mass content of the coating material in the lithium nickel cobalt manganese oxide is selected to be 100-5000 ppm, such as 100 ppm, 300 ppm, 500 ppm, 800 ppm, 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm, 5000 ppm, or any two of the above values ​​within a range.

[0075] In some embodiments, in the positive electrode active material layer, the molar percentage of element Ni, based on the total molar number of Ni, Co, and Mn elements, is ≥0.8; b and c satisfy: 0.1≤b×c≤10. When the molar content of element Ni in the positive electrode active material layer is ≥0.8 (based on the total molar number of Ni, Co, and Mn elements), such as within the range formed by any two of the values ​​above 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.95, the nickel content increases, and the volume change rate of the positive electrode sheet is larger during battery charging, leading to an increased risk of separator and electrode sheet separation. By controlling the product of b and c within the above range, it is more beneficial to improve the initial coulombic efficiency and kinetic performance of the battery.

[0076] In one embodiment, the average particle size of the nickel-cobalt-manganese material in the positive electrode active material layer ranges from 0.5 to 15 μm to improve the lithium-ion transport rate and thus enhance the first coulombic efficiency. For example, the average particle size of the nickel-cobalt-manganese material in the positive electrode active material layer ranges from 0.5 μm, 0.8 μm, 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 12 μm, 15 μm, or any two of these values.

[0077] The method for detecting the average particle size of the nickel-cobalt-manganese material in the positive electrode active material layer is not limited in this application, and those skilled in the art can perform the detection using conventional techniques. For example, the average particle size of the nickel-cobalt-manganese material in the positive electrode active material layer can be detected using the following method:

[0078] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the positive electrode. Place the positive electrode in DMC (dimethyl carbonate) and immerse it at room temperature (25℃, the same below) for 60 minutes. Take it out and air dry it at room temperature.

[0079] Scrape off the positive electrode material from the surface of the positive electrode current collector, take the positive electrode material powder for SEM (scanning electron microscope) testing, with a magnification of 3kx, and use NanoMeasurer to obtain the average particle size of 200 particles through manual labeling or machine statistical method, which is the average particle size of the particles in the positive electrode active material layer.

[0080] In some embodiments, the nickel-cobalt-manganese material comprises polycrystalline particles and single-crystal particles. The average particle size of the polycrystalline particles ranges from 5 to 15 μm, and the average particle size of the single-crystal particles ranges from 0.5 to 5 μm. Using a combination of polycrystalline and single-crystal particles can improve kinetic performance and enhance the first coulombic efficiency. Single-crystal particles refer to particles whose crystal shape is a single, complete particle or an aggregate of fewer than three primary particles; polycrystalline particles refer to particles containing at least three or more crystals. For example, the average particle size range of the polycrystalline particles is within the range formed by any two of the following values: 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, or more; the average particle size range of the single-crystal particles is within the range formed by any two of the following values: 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or more. The particle size of the nickel-cobalt-manganese material can be adjusted through grinding and sintering stages.

[0081] This application does not limit the methods for detecting the particle size of polycrystalline particles and single-crystal particles; those skilled in the art can perform the detection using conventional techniques. For example, the particle size of polycrystalline particles and single-crystal particles can be detected using the following methods:

[0082] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the positive electrode. Place the positive electrode in DMC (dimethyl carbonate) and soak it at room temperature (25℃, the same below) for 60 minutes. Take it out and dry it at room temperature with humidity ≤15%.

[0083] The positive electrode material was scraped off from the surface of the positive electrode current collector, and the positive electrode material powder was subjected to SEM (scanning electron microscope) testing at a magnification of 3kx to identify single-crystal particles and polycrystalline particles. Using NanoMeasurer, 100 single-crystal particles were counted by manual labeling or machine statistical methods, and their average values ​​were calculated to obtain the average size of the single-crystal particles. Similarly, the sizes of 100 polycrystalline particles were counted, and their average values ​​were calculated to obtain the average size of the polycrystalline particles.

[0084] In some embodiments, the mass ratio of the polycrystalline particles to the single-crystal particles is (20~80):(80~20) to better improve kinetic performance and first coulombic efficiency. The mass ratio of the polycrystalline particles to the single-crystal particles is 20:80, 30:70, 40:60, 50:50, 60:40, 40:60, 30:70, 20:80, or any two of the above values ​​within a range.

[0085] This application does not limit the preparation method of the lithium nickel cobalt manganese oxide. Those skilled in the art can prepare the lithium nickel cobalt manganese oxide using conventional techniques, or it can be obtained commercially. For example, the preparation method of the lithium nickel cobalt manganese oxide includes the following steps:

[0086] Ni salt, Co salt, and Mn salt were prepared into solutions respectively;

[0087] Pure water, a complexing agent, and an alkaline solution were added to a reaction vessel. Then, solutions of Ni salt, Co salt, and Mn salt were added simultaneously, while the complexing agent and alkaline solution were continuously added. The reaction system became a suspension. After filtration, washing, and drying, the precursor was obtained.

[0088] The precursor and Li salt are mixed and dispersed, sintered, cooled, crushed (e.g., ground), and sieved to obtain lithium nickel cobalt manganese oxide.

[0089] For example, the Ni salt used includes, but is not limited to, at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel oxalate, and nickel acetate;

[0090] And / or, the Co salt used includes, but is not limited to, at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt oxalate, and cobalt acetate;

[0091] And / or, the Mn salt used includes, but is not limited to, at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate;

[0092] And / or, the Li salt used includes, but is not limited to, at least one of lithium phosphate, lithium dihydrogen phosphate, lithium acetate, lithium hydroxide, lithium carbonate, and lithium nitrate;

[0093] And / or, the complexing agent used includes, but is not limited to, at least one of citric acid and ammonia water;

[0094] And / or, the base used in the alkaline solution includes, but is not limited to, sodium hydroxide.

[0095] In some embodiments, the amounts of Ni salt, Co salt and Mn salt used satisfy the following ratio: Ni element: Co element: Mn element = (0.5-0.95): (0.02-0.3): (0.03-0.2) (molar ratio).

[0096] In some embodiments, when Ni salt, Co salt, and Mn salt are prepared into solutions, the concentration of each salt in the resulting solution is independently 0.5~2.5 mol / L.

[0097] In some embodiments, the molar amount of the complexing agent is 0.5 to 1.5 times the total molar amount of the Ni salt, Co salt, and Mn salt.

[0098] In some embodiments, during the preparation of the precursor, it is necessary to control the pH value of the system within the range of 6 to 8, which can be achieved by adding the alkaline solution.

[0099] In some embodiments, the complexing agent is added in solution form at a concentration of 0.2 to 1.0 mol / L.

[0100] In some embodiments, the alkaline solution contains 1.0% to 4.0% by mass of alkali.

[0101] In some embodiments, the system temperature is controlled within the range of 50~70°C during the preparation of the precursor.

[0102] In some embodiments, pure water, a complexing agent, and an alkaline solution are added to the reactor, followed by the simultaneous addition of solutions of Ni, Co, and Mn salts, while stirring is carried out continuously during the addition of the complexing agent and alkaline solution. For example, the stirring speed is 100-600 rpm.

[0103] In some implementations, the complexing agent is added dropwise.

[0104] In some implementations, the alkaline solution is added dropwise.

[0105] In some implementations, the amounts of the precursor and the Li salt satisfy the following ratio: amount of Li element: sum of amounts of Ni, Co and Mn elements = (1.01~1.10):1.

[0106] In some embodiments, the sintering process is as follows:

[0107] Heat to 500-650℃ and hold for 3-6 hours;

[0108] Heat to 750-950℃ and keep warm for 8-12 hours.

[0109] In some embodiments, the lithium nickel cobalt manganese oxide is a single crystal, and the sintering process for the single crystal is as follows:

[0110] Heat to 500-650℃ and hold for 3-6 hours;

[0111] Heat to 900-950℃ and keep warm for 10-12 hours.

[0112] In some embodiments, the lithium nickel cobalt manganese oxide is polycrystalline, and the sintering process for polycrystalline materials is as follows:

[0113] Heat to 500-650℃ and hold for 3-6 hours;

[0114] Heat to 750-850℃ and keep warm for 10-12 hours.

[0115] Lithium nickel cobalt manganese oxide can also be doped as needed, specifically as follows: when the precursor and Li salt are mixed and dispersed, a salt or oxide containing the corresponding dopant element is added simultaneously. For example, when doping Zr, at least one of zirconium dioxide, zirconium nitrate, etc. can be added; when doping B, at least one of boron trioxide, boric acid, etc. can be added; when doping W, at least one of tungsten trioxide, tungsten nitrate, etc. can be added.

[0116] The lithium nickel cobalt manganese oxide can also be coated as needed. Specifically, a dry coating method (high-temperature solid-state method) is used to coat the surface of the lithium nickel cobalt manganese oxide particles with a coating material, so that the surface of the lithium nickel cobalt manganese oxide particles is partially or completely covered with a coating layer formed by the coating material. In one embodiment, the coating material includes at least one of tungsten oxide, boron oxide, and aluminum oxide.

[0117] In some embodiments, the mass percentage of nickel-cobalt-manganese material in the positive electrode active material layer is 80%-98.5%, such as any two values ​​forming a range of 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98.5% or above.

[0118] In some embodiments, the positive electrode active material includes lithium iron phosphate (LFP). LFP cathodes have low volumetric strain and low stress, which is more conducive to improving and balancing the first-pass coulombic efficiency and kinetic performance.

[0119] In some embodiments, the mass percentage of LFP in the positive electrode active material layer is 1.5%-20%, such as a range formed by any two values ​​of 1.5%, 5%, 10%, 15%, 20% or more.

[0120] In one embodiment, the lithium iron phosphate comprises a first type of particles and a second type of particles. The average particle size of the first type of particles ranges from 0.8 to 3 μm (e.g., within the range formed by any two of the values ​​0.8 μm, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, or above). The average particle size of the second type of particles ranges from 0.1 to 0.5 μm (e.g., within the range formed by any two of the values ​​0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, or above), in order to achieve better kinetic performance and higher initial coulombic efficiency. In some implementations, the mass ratio of the large particles to the small particles is (2~8):(4~6), such as a range formed by any two values ​​of 2:8, 3:7, 4:6 or above, to further improve the dynamic performance and enhance the first coulomb efficiency.

[0121] This application specifies the method for detecting the average particle size of the first type of particles and the second type of particles. Those skilled in the art can perform the detection using conventional techniques. For example, the average particle size of the first type of particles and the second type of particles can be detected using the following method:

[0122] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the positive electrode. Place the positive electrode in DMC (dimethyl carbonate) and soak it at room temperature (25℃, the same below) for 60 minutes. Take it out and dry it at room temperature with humidity ≤15%.

[0123] The positive electrode material was scraped off from the surface of the positive electrode current collector, and the positive electrode material powder was subjected to SEM (scanning electron microscopy) testing.

[0124] The elements of the cathode material were determined by EDS, and lithium iron phosphate was identified by characteristic elements, with Fe being selected as the characteristic element. Then, SEM (scanning electron microscope) testing was performed at a magnification of 10kx to identify the first and second types of particles. Using NanoMeasurer, 100 first-type particles were counted by manual labeling or machine statistical methods, and their average values ​​were calculated to obtain the average size of the first-type particles. Similarly, the size of 100 second-type particles was counted, and their average values ​​were calculated to obtain the average size of the second-type particles.

[0125] The lithium iron phosphate may or may not contain doping elements; this application does not limit the types of doping elements in lithium iron phosphate. In some embodiments, the doping elements in lithium iron phosphate include, but are not limited to, at least one of Ti, V, and Mg. This application does not limit the content of doping elements in lithium iron phosphate. In some embodiments, the mass content of doping elements in lithium iron phosphate is selected to be 100-10000 ppm, such as a range formed by any two of the following values: 100 ppm, 500 ppm, 1000 ppm, 5000 ppm, 10000 ppm, or more.

[0126] The lithium iron phosphate may be free of coating material or have a coating material on part or all of its surface. In some embodiments, the surface of the lithium iron phosphate particles is coated with a carbon layer. In one embodiment, the thickness of the carbon layer in the lithium iron phosphate is selected to be 1~10 nm, such as a range formed by any two values ​​of 1 nm, 3 nm, 5 nm, 7 nm, 10 nm or more.

[0127] This application does not limit the preparation method of the lithium iron phosphate. Those skilled in the art can prepare the lithium iron phosphate using conventional techniques, or it can be obtained commercially. For example, the preparation method of the lithium iron phosphate includes the following steps:

[0128] Lithium iron phosphate and lithium carbonate are mixed and dispersed in an organic solvent, spray-dried, and sintered to obtain lithium iron phosphate.

[0129] In some embodiments, the mass ratio of iron phosphate to lithium carbonate is 1:(1.01~1.10).

[0130] In some embodiments, the sintering temperature during the preparation of lithium iron phosphate is 650~800℃ and the sintering time is 1~5h.

[0131] In some embodiments, the organic solvents used in the preparation of lithium iron phosphate include, but are not limited to, at least one of methanol and ethanol.

[0132] In some embodiments, after sintering, the lithium iron phosphate can be ground, or ground and sieved.

[0133] Lithium iron phosphate can also be doped as needed, specifically as follows: when iron phosphate and lithium carbonate are mixed and dispersed in an organic solvent, a salt or oxide containing the corresponding dopant element is added simultaneously. For example, when doping Ti, at least one of titanium dioxide, tetrabutyl titanate, etc., can be added; when doping Mg, at least one of magnesium oxide, magnesium acetate, etc., can be added; when doping V, at least one of vanadium pentoxide, ammonium metavanadate, etc., can be added.

[0134] In some embodiments, the mass percentage of the positive electrode active material in the positive electrode active material layer is 94.5% to 98.5%, such as 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, or any range formed by any two of the above values.

[0135] In addition to the aforementioned positive electrode active material, the positive electrode active material layer also contains conductive agents and / or binders.

[0136] The conductive agent in the positive electrode active material layer is used to provide conductivity. Any conductive agent can be used without particular limitation, as long as it has suitable electronic conductivity and does not significantly cause adverse chemical changes in the battery. For example, the conductive agent in the positive electrode active material layer includes, but is not limited to, at least one of carbon nanotubes, carbon black, graphite, activated carbon, carbon fibers, mesoporous carbon, and fullerenes, wherein carbon fibers are, for example, carbon nanofibers; and carbon black is, for example, acetylene black, SP (Super P), Ketjen black, etc.

[0137] In some embodiments, the mass percentage of the conductive agent in the positive electrode active material layer is 0.5% to 3.3%, such as 0.5%, 0.7%, 0.8%, 0.9%, 1.0%, 1.2%, 1.4%, 1.5%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.3%, or any range formed by any two of the above values.

[0138] The binder in the positive electrode active material layer is used to improve the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the positive electrode current collector. Any binder can be used without particular limitation, as long as it has suitable adhesive properties and does not significantly cause adverse chemical changes in the battery. For example, the binder in the positive electrode active material layer includes, but is not limited to, fluorinated polyolefin binders, including but not limited to polyvinylidene fluoride (PVDF), PVDF copolymers, or their modified derivatives (e.g., modified with carboxylic acids, acrylic acid, acrylonitrile, etc.).

[0139] In some embodiments, the mass percentage of the binder in the positive electrode active material layer is 1% to 2.2%, such as 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, or any range formed by any two of the above values.

[0140] The positive electrode material can be disposed on one side of the positive electrode current collector or on both sides of the positive electrode current collector.

[0141] This application does not impose any particular restrictions on the positive electrode current collector, as long as it is conductive and will not cause adverse chemical changes in the battery. For example, it may use at least one of the following materials: aluminum, nickel, titanium, stainless steel, sintered carbon; or aluminum or stainless steel that has been surface treated with at least one of carbon, nickel, titanium, silver, etc.

[0142] The positive electrode sheet of this application can be prepared according to conventional methods in the art. For example, the positive electrode active material, conductive agent and binder are dispersed in a solvent to obtain a positive electrode slurry, and then the positive electrode slurry is coated on at least one side of the positive electrode current collector. After drying, rolling, slitting and other processes, the positive electrode sheet is obtained. The solvent in the positive electrode slurry includes, but is not limited to, N-methylpyrrolidone (NMP).

[0143] In some embodiments, the cell further includes a negative electrode sheet, wherein the particle size Dv50 of the negative electrode material is in the range of 4~25μm.

[0144] In some embodiments, the negative electrode sheet includes a negative electrode material with a particle size Dv50 ranging from 4 to 15 μm to improve kinetic performance and enhance the first coulombic efficiency. For example, the particle size Dv50 of the negative electrode material is within the range of 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any two of these values.

[0145] The method for detecting the particle size Dv50 of the negative electrode material is not limited in this application, and those skilled in the art can perform the detection using conventional techniques. For example, the particle size Dv50 of the negative electrode material can be detected using the following method:

[0146] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the negative electrode sheet. Place the negative electrode sheet in DMC (dimethyl carbonate) and soak it in room temperature (25℃, the same below) for 60 minutes. Take it out and dry it at room temperature with humidity ≤15%.

[0147] The negative electrode material is scraped off from the surface of the negative electrode current collector to obtain negative electrode material powder;

[0148] The negative electrode material powder was tested using a laser particle size distribution measuring instrument (Mastersizer 3000). The particle size distribution was measured according to the particle size distribution laser diffraction method (specific steps refer to GB / T19077-2016). The particle size corresponding to the cumulative particle size distribution percentage reaching 50% is Dv50.

[0149] In some embodiments, the negative electrode material includes a negative electrode active material, which includes at least one of graphite and silicon-based materials.

[0150] In some embodiments, the mass percentage of the negative electrode active material in the negative electrode material is 90% to 98%, such as 90%, 92%, 94%, 96%, 98%, or any range formed by any two of the above values.

[0151] The negative electrode material may also contain conductive agents, and / or binders, and / or dispersants.

[0152] The conductive agent in the negative electrode material is used to provide conductivity. Any conductive agent can be used without particular limitation, as long as it has suitable electronic conductivity and does not significantly cause adverse chemical changes in the battery. For example, the conductive agent in the negative electrode material includes, but is not limited to, at least one of carbon nanotubes, carbon black, graphite, carbon fibers, activated carbon, mesoporous carbon, and fullerenes, wherein carbon fibers are, for example, carbon nanofibers; and carbon black is, for example, SP, acetylene black, Ketjen black, etc.

[0153] In some embodiments, the mass percentage of the conductive agent in the negative electrode material is 0 to 5%, such as 0, 1%, 2%, 3%, 4%, 5%, or any range formed by any two of the above values.

[0154] The binder in the negative electrode material is used to improve the adhesion between the negative electrode active material particles and the adhesion between the negative electrode active material and the negative electrode current collector. Any binder can be used without particular limitation, as long as it has suitable adhesive properties and does not significantly cause adverse chemical changes in the battery. For example, the binder in the negative electrode material includes, but is not limited to, at least one of carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, and aqueous acrylic resin.

[0155] In some embodiments, the mass percentage of binder in the negative electrode material is 1.5% to 5%, such as 1.5%, 2%, 3%, 4%, 5%, or any range formed by two of the above values.

[0156] The dispersant in the negative electrode material is used to improve the dispersibility of the negative electrode active material. Any dispersant can be used without particular limitation, as long as it has suitable dispersibility and does not significantly cause adverse chemical changes in the battery. For example, the dispersant in the negative electrode active material layer includes, but is not limited to, at least one of carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and hydrogenated styrene-butadiene rubber (H-SBR).

[0157] In some embodiments, the mass percentage of dispersant in the negative electrode material is 0.3% to 1.5%, such as 0.3%, 0.5%, 0.7%, 1%, 1.2%, 1.5%, or any range formed by any two of the above values.

[0158] The negative electrode material can be composited on one side of the negative electrode current collector or on both sides of the negative electrode current collector.

[0159] This application does not impose any particular restrictions on the negative electrode current collector, as long as it is conductive and will not cause adverse chemical changes in the battery. For example, it may use at least one of the following materials: copper, stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum-cadmium alloy; or copper or stainless steel that has been surface-treated with at least one of carbon, nickel, titanium, silver, etc.

[0160] The negative electrode sheet of this application can be prepared according to conventional methods in the art. For example, the negative electrode active material, conductive agent and binder are dispersed in a solvent to obtain a negative electrode slurry, and then the negative electrode slurry is coated on at least one side of the negative electrode current collector. After drying, rolling, slitting and other processes, the negative electrode sheet is obtained. The solvent in the negative electrode slurry includes, but is not limited to, at least one of deionized water and NMP.

[0161] In some embodiments, the battery further includes an electrolyte comprising a solvent and additives, wherein the solvent comprises at least one selected from ethylene carbonate (EC), diethyl carbonate (DEC), fluoroethylene carbonate (FEC), and dimethyl carbonate (DMC), and the additives comprise at least one selected from 1,3-propanesulfonate lactone (PS), ethylene sulfate (DTD), and methylene disulfonate (MMDS) to reduce the risk of gas generation during the charge and discharge process, reduce the risk of separation between the separator and the electrode, and improve the initial coulombic efficiency of the battery.

[0162] In some embodiments, the mass percentage of solvent in the electrolyte is 75% to 95%, such as 75%, 77%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 95%, or any range formed by any two of the above values.

[0163] In some embodiments, the mass percentage of the additive in the electrolyte is 0.1% to 1%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any range formed by any two of the above values.

[0164] The electrolyte further includes an electrolyte. In one embodiment, the electrolyte includes a lithium salt. Exemplarily, the lithium salt includes, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorodioxalate phosphate (LiDFOP), lithium tetrafluorooxalate phosphate (LiTFOP), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), and lithium difluorophosphate (LiPO2F2). Exemplarily, the concentration of the electrolyte in the electrolyte is 0.8-2.5 mol / L.

[0165] In some embodiments, the diaphragm includes a base membrane and a coating, wherein the coating comprises an organic compound selected from at least one of polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), and styrene-butadiene rubber (SBR).

[0166] Adding organic compounds such as PVDF, PMMA, and SBR to the coating can help improve the bonding strength.

[0167] In some embodiments, the separator satisfies the following condition: the ratio of coating thickness to separator thickness is in the range of 5%-70%. By controlling the ratio of coating thickness to separator thickness within the range of 5%-70%, a moderate proportion of coating thickness in the separator is achieved, which improves adhesion strength while ensuring that the battery has optimal energy density and power characteristics. For example, the ratio of coating thickness to separator thickness is within the range formed by any two values ​​of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or higher. In some embodiments, the base film thickness ranges from 7-15 μm. In some embodiments, the coating thickness ranges from 1-6 μm.

[0168] The method for detecting the coating thickness / diaphragm thickness ratio is not limited in this application, and those skilled in the art can perform the detection using conventional techniques. For example, the coating thickness / diaphragm thickness ratio can be detected using the following method:

[0169] Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the separator. Place the separator in DMC (dimethyl carbonate) and soak it at room temperature (25℃, the same below) for 60 minutes. Take it out and dry it at room temperature with humidity ≤15%.

[0170] Five locations are randomly selected on the diaphragm. The coating thickness and diaphragm thickness at these five locations are measured using a ruler (such as a micrometer). The average value of these measurements is then used to obtain the coating thickness and diaphragm thickness.

[0171] The ratio of coating thickness to diaphragm thickness is then calculated, where the units for coating thickness and diaphragm thickness are the same, such as μm.

[0172] This application does not limit the material of the base membrane, and various membrane materials in the art can be used. For example, the material of the base membrane includes, but is not limited to, at least one of polypropylene and polyethylene.

[0173] In some embodiments, the battery cell includes a wound battery cell, b, and satisfies: 0.5 ≤ b × c ≤ 20.

[0174] A wound battery cell is typically manufactured by winding consecutive positive and negative electrodes and a separator. The separator is located between adjacent positive and negative electrodes. Wound cells have a relatively tight stack, reducing the risk of electrode expansion causing separation from the separator. Controlling the product of b and c within the aforementioned range is more conducive to improving and balancing the initial coulombic efficiency and kinetic performance.

[0175] In one embodiment, the range of b% is 0.6%-10%, which is more conducive to the improvement and balance of initial coulombic efficiency and dynamic performance.

[0176] In one embodiment, the wound cell is a cylindrical core, where b and c satisfy: 1 ​​≤ b × c ≤ 15. The cylindrical core exhibits curling stress, increasing the risk of diaphragm and electrode separation. Controlling the product of b and c within the aforementioned range is more conducive to improving and balancing the initial coulombic efficiency and dynamic performance.

[0177] In one embodiment, the diameter of the cylindrical core is ≥40mm, the height is ≥60mm, and b and c satisfy: 1≤b×c≤12. When the diameter of the cylindrical core is ≥40mm (e.g., within the range formed by any two values ​​of 50mm, 45mm, 40mm, or above), and the height is ≥60mm (e.g., within the range formed by any two values ​​of 60mm, 80mm, 100mm, 120mm, 150mm, 180mm, 200mm, 220mm, 240mm, 260mm, 280mm, or above), the risk of diaphragm and electrode separation is greater. Controlling the product of b and c within the above range is more conducive to improving and balancing the initial coulombic efficiency and kinetic performance.

[0178] In one embodiment, the diameter of the cylindrical core is ≤50mm and the height is ≤280mm.

[0179] In one embodiment, the diameter of the cylindrical core is less than 40 mm and greater than or equal to 10 mm (e.g., within the range formed by any two values ​​of 35 mm, 32 mm, 30 mm, 28 mm, 25 mm, 22 mm, 20 mm, 18 mm, 15 mm, 12 mm, 10 mm or more), and the height is ≤80 mm (e.g., within the range formed by any two values ​​of 80 mm, 75 mm, 70 mm, 65 mm, 60 mm, 55 mm, 50 mm, 39 mm, 35 mm, 32 mm, 30 mm, 28 mm, 25 mm, 22 mm, 20 mm, 18 mm, 15 mm, 12 mm, 10 mm or more). b and c satisfy: 2.5 ≤ b × c ≤ 15, which is more conducive to the improvement and balance of initial coulombic efficiency and dynamic performance.

[0180] In some embodiments, the battery cell further includes a negative tab, with the positive and negative tabs extending from opposite ends in the axial direction of the battery cell.

[0181] In some embodiments, the battery cell further includes a negative tab, with the positive and negative tabs extending from the same end in the axial direction of the battery cell.

[0182] In some embodiments, the battery cell includes a laminated battery cell. A laminated battery cell is a battery cell manufactured by laminating positive electrode plates, negative electrode plates, and a separator using a lamination process. The positive electrode plates and negative electrode plates are separated by a separator, and adjacent positive electrode plates and / or negative electrode plates within the battery cell have a discontinuous structure. The lamination process includes methods such as layering or Z-shaped folding.

[0183] In some embodiments, the length of the stacked cell is greater than or equal to 300 mm (e.g., within the range formed by any two values ​​of 300 mm, 350 mm, 400 mm, 600 mm, 800 mm, 1000 mm, or more), and b and c satisfy: 0.05 ≤ b × c ≤ 8.9. When the length of the stacked cell is greater than or equal to 300 mm, the stacking is loose, increasing the risk of separation between the separator and the electrode. Controlling the product of b and c within the above range is more conducive to improving and balancing the initial coulombic efficiency and kinetic performance.

[0184] In some embodiments, the battery includes a casing, which comprises at least one of an aluminum-plastic film and a metal casing. The aluminum-plastic film is a multi-layer packaging material made of aluminum foil and plastic. From the inside out, the aluminum-plastic film typically includes a heat-sealing layer, a barrier layer, and a substrate / protective layer stacked sequentially.

[0185] Among them, the heat-sealing layer material is cast polypropylene (PP) or modified PP film;

[0186] Function: Heat sealing, which means that under heat and pressure, the layer melts and firmly bonds itself or other PP materials to form a tight seal, ensuring the integrity of the packaging.

[0187] Barrier layer material: aluminum foil;

[0188] Function:

[0189] Barrier properties: Isolates moisture and oxygen, preventing external vapors and oxygen from entering the packaging, while also preventing internal substances (such as electrolyte) from evaporating, thus ensuring battery life and safety;

[0190] Electromagnetic interference protection: It can shield electromagnetic waves;

[0191] Light-blocking properties: Blocks light and protects photosensitive materials.

[0192] Substrate / protective layer material: typically nylon film or polyester film;

[0193] Function:

[0194] Mechanical protection: Provides excellent puncture resistance, abrasion resistance and impact resistance, protecting the internal aluminum layer from scratches or damage;

[0195] Printability: The surface can be printed with product information, brand logos, etc.

[0196] Moisture resistance: Nylon or polyester itself has a certain degree of barrier properties.

[0197] In one embodiment, the housing comprises an aluminum-plastic membrane, wherein b and c satisfy: 0.1 ≤ b × c ≤ 10. The aluminum-plastic membrane has a relatively weak ability to bind the battery cell, and the risk of electrode expansion causing separation from the separator is high. By controlling the product of b and c within the above range, it is more beneficial to improve and balance the initial coulombic efficiency and dynamic performance.

[0198] In one embodiment, the metal shell is selected from at least one of aluminum shell, steel shell, and titanium shell. Specifically, the aluminum shell is made of at least one of aluminum metal and aluminum alloy, and the aluminum alloy includes at least one of aluminum-manganese alloy and aluminum-magnesium alloy; the steel shell is made of at least one of stainless steel, carbon steel, and nickel-plated steel; and the titanium shell is made of at least one of titanium metal and titanium alloy.

[0199] In some embodiments, the surface of the positive electrode sheet is provided with protrusions. A protrusion is a portion that extends beyond the surface of the positive electrode active material layer away from the positive electrode current collector. Protrusions on the positive electrode surface improve the surface roughness of the positive electrode sheet and enhance the adhesion strength between the separator and the electrode sheet. In some embodiments, the size of the protrusion along the direction away from the positive electrode current collector is 5-18 μm, such as 5 μm, 7 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, or any two of these values ​​within a range.

[0200] Electrical appliances

[0201] This application also provides an electrical device that includes the battery. The battery serves as the power source for the electrical device.

[0202] The term "electrical device" refers to any device that can utilize electrical energy and convert it into mechanical energy, thermal energy, light energy, or one or more other energy forms, such as electric motors, electric heaters, and electric light sources. Specifically, it can include, but is not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, and energy storage systems. Mobile devices can include mobile phones, laptops, drones, robot vacuum cleaners, and e-cigarettes; electric vehicles can include pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, and electric trucks.

[0203] The present application is further illustrated below with specific embodiments:

[0204] Example 1

[0205] This embodiment provides a lithium-ion battery, and the specific preparation method is as follows:

[0206] (1) Preparation of positive electrode active material

[0207] Ni(CH3COO)2·4H2O, Co(CH3COO)2·4H2O, and Mn(CH3COO)2·4H2O were weighed according to the molar ratio of Ni, Co, and Mn elements in lithium nickel cobalt manganese oxide (chemical formulas are shown in Table 1), and solutions were prepared separately.

[0208] Pure water, a complexing agent, and an alkaline solution were added to a reaction vessel. Then, solutions of the obtained Ni, Co, and Mn salts were simultaneously added, with the complexing agent and alkaline solution continuously added dropwise. The reaction system temperature was controlled at 60℃ and the pH at 7. The reaction system formed a suspension, which was then filtered, washed, and dried at 120℃ for 12 hours to obtain the precursor. The complexing agent was a citric acid solution with a concentration of 0.5 mol / L, and the molar amount of citric acid in the solution was 1.2 times the total molar amount of Ni, Co, and Mn salts. The alkaline solution was a NaOH solution with a NaOH mass percentage of 3%.

[0209] The lithium source precursor and the sources of doping elements are mixed and dispersed and then sintered in a muffle furnace. After cooling to room temperature, polycrystalline or single-crystal lithium nickel cobalt manganese oxide is obtained. The amounts of lithium source and precursor satisfy the following ratio: the molar amount of Li element : the sum of the molar amounts of Ni, Co and Mn elements = 1.02:1. The sources of doping elements are zirconium dioxide, boron trioxide and tungsten trioxide, and the molar ratio of Zr, B and W is 1:1:1. Based on the total mass of the obtained positive electrode active material, the sum of the mass percentages of Zr, B and W is 4000 ppm.

[0210] The sintering process for polycrystalline materials is as follows:

[0211] Heat to 550℃ and maintain the temperature for 4 hours;

[0212] Cool down to 750℃ and keep warm for 10 hours.

[0213] The sintering process for single crystals is as follows:

[0214] Heat to 500℃ and hold for 3 hours;

[0215] Cool down to 900℃ and keep warm for 10 hours.

[0216] The obtained single crystals and polycrystalline materials were ground and sieved to obtain single crystals and polycrystalline materials with average particle sizes as shown in Table 1. They were then mixed according to the proportions in Table 1, and alumina powder was used as raw material to perform alumina deposition using an ALD atomic deposition instrument to obtain the positive electrode active material. The Al element content in the positive electrode active material was 3665 ppm.

[0217] (2) Preparation of positive electrode sheet

[0218] The obtained positive electrode active material, conductive agent acetylene black and binder PVDF are mixed at a mass ratio of 96:2:2, solvent NMP is added, and the mixture is stirred in a vacuum mixer to obtain positive electrode slurry.

[0219] Organic compounds (types are shown in Table 1) and inorganic compounds (types are shown in Table 1) were mixed according to the mass ratio in Table 1, NMP solvent was added, and the mixture was stirred in a vacuum mixer to obtain positive electrode tab slurry, the solid content of which is shown in Table 1.

[0220] The positive electrode slurry is coated on both sides of the positive electrode current collector aluminum foil (with a positive electrode tab integrally formed thereon) at the speed shown in Table 1. At the same time, there are extrusion nozzles for the tab adhesive on both sides of the positive electrode coating area. The positive electrode tab adhesive slurry is applied by extrusion to form an insulating layer. After drying, it is pressed with an 80t pressure roller and cut to obtain the positive electrode sheet. The thickness of the insulating layer, the dimensions in the first direction, and the dimensions of the positive electrode sheet in the first direction are shown in Table 1.

[0221] (3) Preparation of negative electrode sheet

[0222] The negative electrode active material artificial graphite, conductive agent acetylene black, dispersant CMC and binder SBR are mixed in a mass ratio of 97:1:1:1, deionized water is added, and the mixture is stirred in a vacuum mixer to obtain the negative electrode slurry.

[0223] The negative electrode slurry is coated on both sides of the negative electrode current collector copper foil (with a negative electrode tab integrally formed thereon) at a speed of 45 m / min, dried, rolled with a pressure of 45t, and cut to obtain the negative electrode sheet.

[0224] (4) Preparation of electrolyte

[0225] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 30:30:40 to obtain an organic solvent. Dry lithium salts LiPF6 and LiFSI were dissolved in the obtained organic solvent to prepare an electrolyte with a LiPF6 concentration of 1.0 mol / L and a LiFSI concentration of 1.0 mol / L.

[0226] (5) Preparation of lithium-ion batteries

[0227] The positive electrode, separator (PE), and negative electrode are stacked in sequence, with the separator acting as an isolation between the positive and negative electrode sheets. The bare cell is obtained through the stacking process.

[0228] The bare battery cell is placed in an outer packaging shell (material: aluminum-plastic film), dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a lithium-ion battery is obtained.

[0229] Among them, the positive and negative tabs are led out at both ends of the battery cell along the first direction.

[0230] The transformation procedure is as follows:

[0231] After being placed at 25℃ for 24 hours, the glass is placed in a glass clamp with a clamping pressure of 0.4-0.6 MPa; at 25℃,

[0232] 1) Let it stand for 10 minutes;

[0233] 2) Charge at a rate of 0.02C, with a cutoff voltage of 3.2V;

[0234] 3) Let it stand for 10 minutes.

[0235] 4) Charge at a rate of 0.05C, with a cutoff voltage of 3.4V;

[0236] 5) Let stand for 10 minutes.

[0237] 6) Charge at a rate of 0.08C, with a cutoff voltage of 3.75V;

[0238] 7) End.

[0239] Examples 2-34 and Comparative Examples 1-6

[0240] These examples and comparative examples all provide a lithium-ion battery, and the preparation method is similar to that of Example 1. The differences are as follows: the chemical formula of lithium nickel cobalt manganese oxide, the crystal form of lithium nickel cobalt manganese oxide and the average particle size of each crystal form (the average particle size is adjusted by sintering and grinding sieving) (if a combination of single crystal and polycrystalline is used, the mass ratio of the two is also included), the coating speed of the positive electrode slurry, the types of organic and inorganic compounds in the positive electrode tab adhesive, the mass ratio of the two and the solid content of the positive electrode tab adhesive slurry, the width of the positive electrode tab adhesive extrusion nozzle, the size of the insulating layer in the first direction, the size of the positive electrode sheet in the first direction, and the form of the shell, the cell and the direction of the positive and negative electrode tabs are shown in Table 1.

[0241] In Examples 28-30, during assembly, a positive electrode, a negative electrode, and a separator are placed between the positive and negative electrode sheets. A cylindrical bare cell is obtained by a winding process, and the cylindrical bare cell is placed in the aluminum-plastic film of the outer packaging shell.

[0242] In Examples 31-32, during assembly, a positive electrode, a negative electrode, and a separator are placed between the positive and negative electrode sheets. A cylindrical bare cell is obtained through a winding process, and the bare cell is placed in an outer packaging shell made of aluminum or steel.

[0243] In Examples 28-32, the diameter of the cylindrical core is 45mm.

[0244] Table 1

[0245]

[0246] Continued from Table 1

[0247]

[0248] Continued from Table 1

[0249]

[0250] Continued from Table 1

[0251]

[0252] Continued from Table 1

[0253]

[0254] The following methods were used to test the batteries of each embodiment and comparative example:

[0255] (1) Fast charging time test:

[0256] Preparation of three-electrode copper wire: The copper wire is wound around the fixed copper foil surface, and the two ends of the copper wire are evenly attached to the copper foil.

[0257] Assembly and formation: Prepare the required positive and negative electrode plates and copper wires. Stack the electrode plates in the following order: negative electrode plate, separator, copper wire, separator, positive electrode plate, separator, negative electrode plate. The positive electrode plate should be placed in the middle of the negative electrode plate, and the negative electrode plates should be completely aligned. After stacking, the outermost negative electrode sheet is peeled off. The copper wire ends (processed ends) are positioned 32±5 mm from the top edge and 40.5±5 mm to the left and right of the cell center. An 81×81 mm² separator is then added, followed by the negative electrode sheet. The copper wire arrangement is complete. A soldering iron is used to transfer the copper wires (soldering temperature 300℃, time 5~10s). During ultrasonic welding, the cell is handled gently to prevent the copper wires from breaking during transport. The resulting bare cell is placed in its outer packaging. After drying and meeting requirements, electrolyte is injected. The cell undergoes vacuum sealing, settling, and formation, following the steps outlined above. The battery is then charged at a constant current of 0.33C to 4.25V, charged at a constant voltage until the current is less than or equal to 0.05C, and discharged at 0.33C to the lower limit voltage of 2.5V. This process is repeated. Repeat the above steps three times, using the capacity discharged in the third cycle as the battery discharge capacity C. Then, charge the battery at a constant current of 1C to the upper limit voltage, with a cutoff current of 0.05C. Then discharge at 1C to the lower limit voltage of 2.5V, completing one cycle. Perform 100 charge-discharge cycles. After that, let the battery rest for 10 minutes, discharge at 1C to 2.5V, let it rest for 10 minutes, and then charge at 0.33C to 10% SOC. Then, charge at progressively lower rates of 0.4C to 4C, 3.6C, 3.2C, 2.8C, 2.4C, 2.0C, 1.6C, 1.2C, 0.8C, and 0.4C. The cutoff condition for each charge is charging to the upper limit voltage of 4.25V or the auxiliary voltage of 0mV. Record the charging time between 10% SOC (10%×C) and 80% SOC (80%×C).

[0258] (2) First Coulomb efficiency

[0259] The lithium-ion battery was charged to 4.25V at a constant current of 0.33C at 25℃, and then charged to a constant voltage until the current dropped to 0.05C. After standing for 5 minutes, the battery was discharged to 2.5V at a constant current of 0.33C. The initial discharge capacity and charge capacity were obtained. The initial coulombic efficiency = initial discharge capacity / initial charge capacity × 100%.

[0260] The test results are shown in Table 2.

[0261] Table 2

[0262]

[0263] The batteries prepared in the various embodiments of this application have a charging time of less than 20 minutes and an initial coulombic efficiency of more than 84%, which shows that the batteries containing this application have both excellent fast charging performance and initial coulombic efficiency.

[0264] As can be seen from the comparison of Examples 1-6 with Examples 7-11, 16, and 18, and the comparison of Examples 14-15 with Examples 12-13, 17, and 19, when the values ​​of b and c meet the preferred range described in this application, the fast charging performance and the first coulombic efficiency are better.

[0265] Comparing Examples 1-6 with Examples 14-15, and Examples 7-11, 16, and 18 with Examples 12-13, 17, and 19, it can be seen that when the battery satisfies 0.05≤b×c≤10, the battery's fast charging performance and initial coulombic efficiency are better.

[0266] According to Comparative Examples 1 to 6, even if the values ​​of b and c are within appropriate ranges, the fast charging performance and initial coulombic efficiency of the battery deteriorate when the value of b × c exceeds the range of 0.014 to 30.

[0267] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this article and are not intended to limit the scope of protection of this article. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this article without departing from the essence and scope of the technical solutions of this article.

Claims

1. A battery, characterized in that, The battery cell includes a positive electrode plate, a positive electrode tab, and an electrolyte. The positive electrode plate is connected to the positive electrode tab, with the direction in which the positive electrode plate leads out of the positive electrode tab being the first direction; The positive electrode sheet includes a positive current collector, a positive active material layer, and an insulating layer. The positive current collector includes a first region close to the positive electrode tab and a second region away from the positive electrode tab. An insulating layer is provided on at least one surface of the first region, and a positive active material layer is provided on at least one surface of the second region. The positive active material layer includes a positive active material, which includes a nickel-cobalt-manganese material. The battery satisfies: 0.05 ≤ b × c ≤ 10. Wherein, b% = the dimension of the insulating layer in the first direction / the dimension of the positive electrode sheet in the first direction × 100%; c represents the degree of unevenness of the surface of the positive electrode active material layer on the side away from the positive electrode current collector; The range of b% is 0.4% to 6%; The range of c is 0.1 μm to 2.5 μm; The nickel-cobalt-manganese material includes lithium nickel cobalt-manganese oxide, the chemical formula of which is Li. a Ni x Co y Mn 1-x-y O2, where a ranges from 0.9 to 1.1; 0 <x<1;0<y<1;x+y<1; The lithium nickel cobalt manganese oxide also contains element M, which is selected from at least one of Zr, Mo, B, Al, W, Sr, Mg, Ca, Ta, Ti, Nb, Y, Ta, and Sb. In the positive electrode active material layer, the mass percentage of nickel-cobalt-manganese material is 80%-98.5%; The insulating layer comprises an organic compound and an inorganic compound, wherein the mass ratio of the organic compound to the inorganic compound is (10-50):(50-90), wherein the organic compound includes at least one of polyvinylidene fluoride and polyacrylic acid, and the inorganic compound includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite.

2. The battery as described in claim 1, characterized in that, The size of the insulating layer in the first direction ranges from 2 to 10 mm.

3. The battery as described in claim 2, characterized in that, The size of the insulating layer in the first direction ranges from 4 to 7 mm.

4. The battery as described in claim 1, characterized in that, The positive electrode tab and the positive electrode current collector are integrated into one unit.

5. The battery as described in claim 1, characterized in that, The thickness of the insulating layer ranges from 10 to 100 μm.

6. The battery as claimed in claim 1, characterized in that, The first region does not have a positive electrode active material layer, and the insulating layer is located in the first region.

7. The battery as described in claim 6, characterized in that, Parallel to the positive electrode tab lead-out direction, the insulating layer extends into the second region and partially overlaps with the positive electrode active material layer. The size of the overlapping area between the insulating layer and the positive electrode active material layer in the first direction ranges from 0.1 to 0.5 mm.

8. The battery as claimed in claim 7, characterized in that, Part of the insulating layer is located on the surface of the positive electrode active material layer away from the positive electrode current collector.

9. The battery as claimed in claim 1, characterized in that, The insulating layer covers a portion of the positive electrode tab, and the area covered by the insulating layer on the positive electrode tab has a size ranging from 0.5 to 4 mm in the first direction.

10. The battery as claimed in claim 1, characterized in that, In the positive electrode active material layer, the molar percentage of element Ni is ≥0.8 based on the total molar number of Ni, Co and Mn elements; b and c satisfy: 0.1≤b×c≤10.

11. The battery as claimed in claim 1, characterized in that, In the positive electrode active material layer, the average particle size of the nickel-cobalt-manganese material ranges from 0.5 to 15 μm.

12. The battery as claimed in claim 1, characterized in that, The nickel-cobalt-manganese material includes polycrystalline particles and single-crystal particles. The average particle size of the polycrystalline particles ranges from 5 to 15 μm, and the average particle size of the single-crystal particles ranges from 0.5 to 5 μm.

13. The battery as claimed in claim 1, characterized in that, The positive electrode active material also includes lithium iron phosphate.

14. The battery as claimed in claim 13, characterized in that, The lithium iron phosphate comprises a first type of particle and a second type of particle. The average particle size of the first type of particle ranges from 0.8 to 3 μm, and the average particle size of the second type of particle ranges from greater than or equal to 0.1 μm to less than 0.8 μm.

15. The battery as claimed in claim 1, characterized in that, The battery cell also includes a negative electrode sheet, which comprises a negative electrode material, and the particle size Dv50 of the negative electrode material is in the range of 4~25μm.

16. The battery as claimed in claim 1, characterized in that, The electrolyte includes a solvent and an additive, wherein the solvent includes at least one of ethylene carbonate, diethyl carbonate, fluoroethylene carbonate, and dimethyl carbonate, and the additive includes at least one of 1,3-propanesulfonate lactone, ethylene sulfate, and methanedisulfonate.

17. The battery as claimed in claim 1, characterized in that, The battery cell also includes a separator, which comprises a base film and a coating, wherein the coating contains an organic compound selected from at least one of polyvinylidene fluoride, polymethyl methacrylate, and styrene-butadiene rubber.

18. The battery as claimed in claim 17, characterized in that, The diaphragm satisfies the following condition: the ratio of coating thickness to diaphragm thickness is in the range of 5%-70%.

19. The battery as claimed in claim 1, characterized in that, The battery cell includes a wound battery cell, where b and c satisfy: 0.5 ≤ b × c ≤ 20.

20. The battery as claimed in claim 19, characterized in that, The wound cell is a cylindrical core, and b and c satisfy: 1≤b×c≤15.

21. The battery as claimed in claim 20, characterized in that, The diameter of the cylindrical core is ≥40mm, the height is ≥60mm, and b and c satisfy 1≤b×c≤12.

22. The battery as claimed in claim 21, characterized in that, The diameter of the cylindrical core is ≤50mm and the height is ≤280mm.

23. The battery as claimed in claim 20, characterized in that, The diameter of the cylindrical core is less than 40mm and greater than or equal to 10mm, and the height is ≤80mm. b and c satisfy: 2.5≤b×c≤15.

24. The battery as claimed in claim 20, characterized in that, The battery cell also includes a negative electrode tab, with the positive and negative electrodes extending from opposite ends along the axial direction of the battery cell.

25. The battery as claimed in claim 20, characterized in that, The battery cell also includes a negative electrode tab, and the positive and negative electrodes are led out from the same end in the axial direction of the battery cell.

26. The battery as claimed in claim 1, characterized in that, The battery cell includes laminated battery cells.

27. The battery as claimed in claim 26, characterized in that, The length of the laminated cell is greater than or equal to 300 mm, and b and c satisfy: 0.05≤b×c≤8.

9.

28. The battery as claimed in claim 1, characterized in that, The battery includes a casing, which includes at least one of an aluminum-plastic film and a metal casing.

29. The battery as claimed in claim 28, characterized in that, The housing comprises an aluminum-plastic film, where b and c satisfy: 0.1 ≤ b × c ≤ 10.

30. The battery as claimed in claim 28, characterized in that, The metal shell is selected from at least one of aluminum shell, steel shell, and titanium shell.

31. The battery as claimed in claim 1, characterized in that, The surface of the positive electrode is provided with a protrusion, and the size of the protrusion in the direction away from the positive electrode current collector is 5-18 μm.

32. An electrical appliance, characterized in that, Includes the battery as described in any one of claims 1 to 31.

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