Battery cell, battery device and electrical device

Abstract

Provided in the present application are a battery cell, a battery device and an electrical device. With respect to the battery cell of the present application, the areal density of a positive electrode film layer on a single side is 0.33 g / 1540.25 mm2 to 0.4 g / 1540.25 mm2, and the areal density of a negative electrode film layer on a single side is 0.15 g / 1540.25 mm2 to 0.19 g / 1540.25 mm2; in a first direction, the size of the positive electrode film layer is W1 mm, and the size of the negative electrode film layer is W2 mm, wherein W2>W1, and the difference between W2 and W1 is 3 mm to 5 mm.

Description

Battery monomer, battery device and electric device TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, in particular to a battery monomer, a battery device and an electric device. BACKGROUND

[0002] In recent years, batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the popularization of battery applications, higher requirements are put forward for its energy density, fast charging performance, cycle performance, service life, safety performance, etc.

[0003] SUMMARY

[0004] The present application aims to provide a new type of battery monomer which has excellent energy density, fast charging performance, cycle performance, and can also have a lower direct current internal resistance.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a battery monomer, comprising a positive electrode sheet and a negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises lithium-containing phosphate, the area density of one side of the positive electrode film layer is 0.33g / 1540.25mm 2 to 0.4g / 1540.25mm 2 ; the area density of one side of the negative electrode film layer is 0.15g / 1540.25mm 2 to 0.19g / 1540.25mm 2 ; the positive electrode current collector comprises a positive electrode current collecting part and at least two positive electrode tabs arranged on the same side of the positive electrode current collecting part, the positive electrode tabs extending out from the positive electrode current collecting part along a first direction; the negative electrode current collector comprises a negative electrode current collecting part and at least two negative electrode tabs arranged on the same side of the negative electrode current collecting part, the negative electrode tabs extending out from the negative electrode current collecting part along the first direction; along the first direction, the size of the positive electrode film layer is W1mm, and the size of the negative electrode film layer is W2mm, wherein W2>W1, and the difference between W2 and W1 is 3mm to 5mm.

[0006] The formation of lithium dendrites is closely related to the capacity design of the positive and negative electrode sheets. By reasonably controlling the area density of the positive and negative electrode sheets within a reasonable range, the current density in the positive and negative electrode films is more uniform, effectively solving the problem of large-area lithium precipitation on the negative electrode sheet. Furthermore, as the charging rate of the battery monomer increases, the negative electrode film near the root of the tab is more prone to lithium dendrite formation due to the electron accumulation zone at the root of the tab. Based on the reasonable control of the area density of the positive and negative electrode films, by further reasonably controlling the difference between the size W2 of the negative electrode film and the size W1 of the positive electrode film, the problem of lithium precipitation near the root of the tab on the negative electrode sheet can be further improved, thereby enabling the battery to have excellent fast-charging performance and cycle performance.

[0007] In any embodiment, the area density of the positive electrode film on one side is 0.335 g / 15 40.25 mm 2 to 0.38 g / 15 40.25 mm 2 , and the area density of the negative electrode film on one side is 0.15 g / 15 40.25 mm 2 to 0.165 g / 15 40.25 mm 2 .

[0008] When the coating area density of the positive and negative electrode films in the battery monomer provided by the application is within the above range, the energy density and fast-charging performance of the battery can be further improved.

[0009] In any embodiment, the compaction density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3 .

[0010] In any embodiment, the compaction density of the positive electrode sheet is 2.4 g / cm 3 to 2.55 g / cm 3 .

[0011] When the compaction density of the positive electrode sheet is within the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0012] In any embodiment, the compaction density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 .

[0013] In any embodiment, the compaction density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm 3 .

[0014] When the compaction density of the negative electrode sheet is in the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0015] In any embodiment, the negative electrode film layer comprises a negative electrode active material, the average particle size Dv50 of the negative electrode active material is 8 μm to 15 μm, and the negative electrode active material comprises graphite.

[0016] In any embodiment, the average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm.

[0017] In the battery cell provided in the present application, when the graphite as the negative electrode active material has a particle size in the above range, the fast-charging performance of the battery can be further improved, and the DC internal resistance of the battery cell can also be improved, thereby reducing the heat generation of the battery.

[0018] In any embodiment, the graphitization degree of the negative electrode active material is 90% to 95%.

[0019] In any embodiment, the graphitization degree of the negative electrode active material is 92% to 95%.

[0020] When the graphitization degree of the negative electrode active material is in the above range, the capacity can be further improved.

[0021] In any embodiment, the negative electrode film layer comprises a first negative electrode active material layer arranged on the surface of the negative electrode current collector and a second negative electrode active material layer arranged on the side of the first negative electrode active material layer away from the negative electrode current collector, the negative electrode active material in the first negative electrode active material layer comprises a first artificial graphite, the negative electrode active material in the second negative electrode active material layer comprises a second artificial graphite, and the average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

[0022] In any embodiment, the average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

[0023] In any embodiment, the average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

[0024] In any embodiment, the average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

[0025] In the battery cell provided in the present application, when the double-layer coating scheme described above is used in the negative electrode film layer, the kinetic performance of the battery can be further improved.

[0026] In any embodiment, the thickness of the negative electrode current collector is 4 μm to 6 μm.

[0027] In any embodiment, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 12 to 20.

[0028] In any embodiment, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 13 to 20.

[0029] In the battery cell provided by the present application, when the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is within the above range, the energy density and the fast-charging performance of the battery can be further improved.

[0030] In any embodiment, the battery cell comprises an electrolyte, and the electrolyte comprises an organic solvent, which comprises a carboxylic acid ester solvent and a carbonate solvent.

[0031] In the battery cell provided by the present application, when the organic solvent of the above type is used in the electrolyte, the kinetic performance of the battery can be further improved.

[0032] In any embodiment, the organic solvent comprises a linear carboxylic acid ester, and the mass fraction of the linear carboxylic acid ester is 40% to 75%, based on the total mass of the electrolyte.

[0033] In any embodiment, the linear carboxylic acid ester has a general structure of R1-COO-R2, wherein R1 and R2 each independently comprises one or more of C1-C5 alkyl and C1-C5 haloalkyl.

[0034] In any embodiment, the linear carboxylic acid ester comprises one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

[0035] When the linear carboxylic acid ester of the above type and mass fraction is used as the organic solvent in the electrolyte, the linear carboxylic acid ester can effectively improve the electrolyte conductivity due to its low viscosity, thereby further improving the fast-charging performance of the battery.

[0036] In any embodiment, the organic solvent comprises a carbonate solvent, which comprises a linear carbonate and a cyclic carbonate, and the mass fraction of the linear carbonate is 10% to 40%, based on the total mass of the electrolyte.

[0037] In any embodiment, the cyclic carbonate comprises one or more of ethylene carbonate and propylene carbonate, and the linear carbonate comprises one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0038] In any embodiment, the linear carbonate comprises dimethyl carbonate, and the mass fraction of the dimethyl carbonate is 5% to 15%, based on the total mass of the electrolyte.

[0039] When the carbonates of the above type and mass ratio are used as the organic solvent in the electrolyte, the side reactions and the degree of gas production of the battery during the cycle process can be improved, so that the battery has good cycle performance.

[0040] In any embodiment, the electrolyte comprises dimethyl carbonate and linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 2.0 to 7.0.

[0041] In any embodiment, the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.0.

[0042] When the dimethyl carbonate and the linear carboxylic acid ester of the above mass ratio are used as the organic solvent in the electrolyte, the combination of the two solvents can further improve the fast charging performance and cycle performance of the battery.

[0043] In any embodiment, the electrolyte comprises lithium salt, and the mass ratio of the lithium salt is 13% to 20% based on the total mass of the electrolyte.

[0044] In any embodiment, the lithium salt comprises at least two of lithium hexafluorophosphate LiPF6 and fluorine-containing sulfonimide salt, and the fluorine-containing sulfonimide salt comprises one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0045] Lithium hexafluorophosphate is not easy to produce gas during the cycle process, which can further improve the cycle performance of the battery; and the dissociation ability of fluorine-containing sulfonimide salt is strong, which can further improve the fast charging performance of the battery.

[0046] In any embodiment, the lithium salt comprises lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonylimide LiFSI.

[0047] In any embodiment, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfonylimide LiFSI in the electrolyte is 1.2:1 to 2:1.

[0048] When lithium hexafluorophosphate and lithium bisfluorosulfonylimide of the above mass ratio range are used in the electrolyte, the fast charging performance and cycle performance of the battery can be further improved.

[0049] In any embodiment, the electrolyte further comprises an additive, and the additive comprises a carbonate additive.

[0050] In any embodiment, the mass ratio of the carbonate additive in the electrolyte is 0.5% to 7% based on the total mass of the electrolyte.

[0051] In any embodiment, the carbonate additive includes vinylene carbonate VC and fluoroethylene carbonate FEC.

[0052] The battery cell provided in the present application further adds a carbonate additive with a mass ratio within the above range, such as fluoroethylene carbonate and vinylene carbonate, which can form an SEI film on the negative electrode surface, thereby reducing the side reactions between the electrode and the electrolyte, and further improving the cycle performance of the battery.

[0053] In any embodiment, the additive includes vinylene carbonate VC; the mass ratio of the vinylene carbonate VC in the electrolyte is 0.5% to 2% based on the total mass of the electrolyte.

[0054] When the electrolyte adds the vinylene carbonate within the above mass ratio range as an additive, the SEI film formed is more stable, which is beneficial to further improve the cycle performance of the battery.

[0055] In any embodiment, the additive includes fluoroethylene carbonate FEC; the mass ratio of the fluoroethylene carbonate FEC in the electrolyte is 0.1% to 1% based on the total mass of the electrolyte.

[0056] When the electrolyte adds the fluoroethylene carbonate within the above mass ratio range as an additive, the SEI film formed has low impedance, which can further improve the fast charging performance of the battery.

[0057] In any embodiment, the lithium-containing phosphate has a general formula as shown in Formula I,

[0058] Li x A y Me a M b P 1-c X c Y z Formula I,

[0059] wherein 0.1≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or more of Na, K, Mg; Me includes one or more of Mn, Fe, Co, Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X includes one or more of S, Si, Cl, B, C, N; Y includes one or more of O, F.

[0060] When the lithium-containing phosphate as the positive electrode active material has the above chemical formula, the energy density of the battery can be further improved.

[0061] In any embodiment, M comprises one or more of Al, Ti, V, Mg.

[0062] In any embodiment, the positive electrode active material satisfies at least one of the following:

[0063] (1) the positive electrode active material contains Al element, the mass content is 0.01-0.05%, based on the total mass of the positive electrode active material;

[0064] (2) the positive electrode active material contains Ti element, the mass content is 0.01-0.03%, based on the total mass of the positive electrode active material;

[0065] (3) the positive electrode active material contains V element, the mass content is 0.1-0.3%, based on the total mass of the positive electrode active material;

[0066] (4) the positive electrode active material contains Mg element, the mass content is 0.001-0.01%, based on the total mass of the positive electrode active material.

[0067] When the lithium-containing phosphate as the positive electrode active material contains Al, Ti, V and other elements, the specific capacity can be further improved.

[0068] In any embodiment, in the cross section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate comprises first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1-3 μm.

[0069] In the battery cell provided by the application, when the positive electrode active material contains lithium-containing phosphate particles with a longest diameter of 0.05-0.3 μm, the direct current internal resistance of the battery cell can be further improved, thereby further reducing the heat generation of the battery, and the battery has excellent safety performance.

[0070] In the battery cell provided by the application, when the lithium-containing phosphate as the positive electrode active material contains first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1-3 μm, the compaction density of the electrode sheet is improved by the size grading of the particles, thereby further improving the energy density of the battery.

[0071] In any embodiment, in the cross section of the positive electrode film layer along the thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

[0072] When the number of first lithium-containing phosphate particles having a longest diameter of 0.05 μm to 0.3 μm is greater than the number of second lithium-containing phosphate particles having a longest diameter of 1 μm to 3 μm, the DC internal resistance and the fast charging performance of the battery can be further improved.

[0073] In any embodiment, a distance between center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, the center lines being parallel to the first direction; and / or,

[0074] A distance between center lines of two adjacent negative electrode tabs is 10 mm to 350 mm, the center lines being parallel to the first direction.

[0075] In any embodiment, a distance between center lines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or,

[0076] A distance between center lines of two adjacent negative electrode tabs is 20 mm to 330 mm.

[0077] The battery cell provided in the present application can further improve the DC internal resistance of the battery cell when the positive and negative current collectors include at least two tabs having the above structural features, thereby further reducing the heat generation of the battery and making the battery have better safety performance.

[0078] In any embodiment, the battery cell further includes a top cover including a positive electrode terminal and a negative electrode terminal having opposite polarities, the positive electrode terminal and the negative electrode terminal being respectively used to be electrically connected with the positive and negative tabs.

[0079] In a conventional battery, a jumper is needed to connect the electrode terminal and the tab, but the utilization rate of the electrode assembly is lost, and the energy density of the battery is reduced. When the battery cell provided in the present application adopts the above structure, the jumper is cancelled, which can effectively solve this problem, reduce the internal resistance of the battery, and further improve the energy density and the fast charging performance of the battery.

[0080] In any embodiment, the shell of the battery is square, the thickness of the shell is 30 mm to 55 mm, the width of the shell is 150 mm to 250 mm, and the height of the shell is 90 mm to 120 mm.

[0081] In any embodiment, the battery cell is configured to have a charging time of 10-17 min from 10% SOC to 80% SOC at room temperature.

[0082] The battery cell provided in the present application has excellent fast charging performance.

[0083] The second aspect of the present application also provides a battery device comprising the battery cell of the first aspect of the present application, the battery device being at least one of a battery module, a battery pack, and an energy storage device.

[0084] The third aspect of the present application also provides a power consumption device comprising the battery cell of the first aspect of the present application or the battery device of the second aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0085] FIG. 1 is a schematic diagram of the size of a film layer of a pole piece according to an embodiment of the present application;

[0086] FIG. 2 is a scanning electron microscope (SEM) observation result of a longitudinal cross section of a positive pole piece according to an embodiment of the present application;

[0087] FIG. 3 is a schematic diagram of a pole piece according to an embodiment of the present application;

[0088] FIG. 4 is an exploded view of a battery cell according to an embodiment of the present application;

[0089] FIG. 5 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0090] FIG. 6 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0091] FIG. 7 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0092] FIG. 8 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0093] FIG. 9 is an exploded view of the battery cell according to an embodiment of the present application shown in FIG. 8;

[0094] FIG. 10 is a schematic diagram of a battery module according to an embodiment of the present application;

[0095] FIG. 11 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0096] FIG. 12 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 11;

[0097] FIG. 13 is a schematic diagram of a power consumption device using the battery cell according to an embodiment of the present application as a power source.

[0098] BRIEF DESCRIPTION OF DRAWINGS

[0099] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 case; 52 electrode assembly; 53 top cover assembly; 10 battery cell; 11 current collector; 11a current collecting portion; 111a positive electrode current collecting portion; 112a negative electrode current collecting portion; 11b tab; 111b positive electrode tab; 112b negative electrode tab; F1 first direction; W1 dimension of the positive electrode film layer in the first direction; W2 dimension of the negative electrode film layer in the first direction; L center line; 13 top cover; 131 electrode terminal; 14 case. DETAILED DESCRIPTION

[0100] Hereinafter, embodiments of the battery cell and the electric device according to the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters that are well known, repeated description of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0101] The "ranges" disclosed in the present application are defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The ranges defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" represents a shorthand manner of describing each and every numerical value that is contained in the range between "a" and "b," wherein "a" and "b" are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand manner of describing these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like.

[0102] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0103] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0104] If not specified otherwise, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method comprising step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0105] If not specified otherwise, the terms "comprising" and "including" as used in the present application are open-ended. For example, the terms "comprising" and "including" can mean that other components not listed can also be included or can mean that only the listed components are included.

[0106] If not specified otherwise, the term "or" in the present application is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following satisfy the condition "A or B": A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).

[0107] As the charging rate of the battery cell increases, lithium ions are more quickly stripped from the positive active material, and the lithium ion concentration distribution in the electrolyte phase can be uneven, thereby causing lithium ions to easily accumulate on the surface of the negative active material in a local area and not be able to be inserted into the negative active material in equal amounts, so as to obtain electrons on the surface of the negative active material and form a silver-white metal lithium element, i.e., "lithium dendrites". The formation of lithium dendrites not only causes the performance of the battery to decrease, such as a shortened cycle life, poor fast-charging performance, and the like. At the same time, the continuously deposited metal lithium element also falls off from the surface of the negative active material, thereby forming "dead lithium" that cannot continue to participate in the reaction, resulting in a decrease in the energy density of the secondary battery.

[0108] In order to solve the above problems, the present application provides a battery cell, comprising a positive electrode sheet and a negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, wherein the positive electrode film layer comprises a positive active material, the positive active material comprising a lithium-containing phosphate, the areal density of a single side of the positive electrode film layer being 0.33 g / 15 40.25 mm 2 to 0.4 g / 15 40.25 mm 2 ; the areal density of a single side of the negative electrode film layer being 0.15 g / 15 40.25 mm 2to 0.19 g / 15 40.25 mm 2 ; the positive current collector comprises a positive current collecting portion and at least two positive tabs disposed on the same side of the positive current collecting portion, the positive tabs extending from the positive current collecting portion along a first direction; the negative current collector comprises a negative current collecting portion and at least two negative tabs disposed on the same side of the negative current collecting portion, the negative tabs extending from the negative current collecting portion along the first direction; along the first direction, the size of the positive film layer is W1 mm, and the size of the negative film layer is W2 mm, where W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm.

[0109] As used herein, the "areal density" of a positive film layer or a negative film layer has the meaning known in the art and can be tested using methods known in the art. For example, a single-side coated and cold-pressed negative tab (if it is a double-side coated negative tab, the negative film layer on one side can be wiped off first) is punched into a small disc with an area of S1, weighed, and recorded as M1. Then the negative film layer of the weighed negative tab is wiped off, the weight of the negative current collector is weighed and recorded as M0, and the areal density of the negative film layer = (weight of the negative tab M1 - weight of the negative current collector M0) / S1. To ensure the accuracy of the test results, multiple groups (e.g., 10 groups) of samples to be tested can be tested, and the average value is calculated as the test result.

[0110] In some embodiments, the positive tab, the negative tab, and the separator film can be made into an electrode assembly through a winding process or a stacking process.

[0111] In some embodiments, the battery cell is a wound battery. As shown in FIG. 1, after the tab is unfolded from the wound state, the positive current collector comprises a positive current collecting portion 111a and at least two positive tabs 111b disposed on the same side of the positive current collecting portion 111a, the positive tabs 111b extending from the positive current collecting portion 111a along a first direction F1; the negative current collector comprises a negative current collecting portion 112a and at least two negative tabs 112b disposed on the same side of the negative current collecting portion 112a, the negative tabs 112b extending from the negative current collecting portion 112a along the first direction F1. Wherein the size of the negative film layer along the first direction W2 > the size of the positive film layer along the first direction W1, and the difference is 3 mm to 5 mm.

[0112] The formation of lithium dendrites is closely related to the capacity design of the positive and negative electrode sheets. By reasonably controlling the areal density of the positive and negative electrode sheets within a reasonable range, the current density in the positive and negative electrode films is more uniform, effectively solving the problem of large-area lithium precipitation on the negative electrode sheet. Furthermore, as the charging rate of the battery monomer increases, the negative electrode film near the root of the tab is more prone to lithium dendrite formation due to the electron accumulation zone at the root of the tab. Based on the reasonable control of the areal density of the positive and negative electrode films, by further reasonably controlling the difference between the size W2 of the negative electrode film and the size W1 of the positive electrode film, the problem of lithium precipitation near the root of the tab on the negative electrode sheet can be further improved, thereby enabling the battery to have excellent fast-charging performance and cycle performance.

[0113] [the negative electrode sheet]

[0114] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector. As an example, the negative electrode current collector has two opposite surfaces in the thickness direction of itself, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0115] In some embodiments, the areal density of the negative electrode film layer is 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 , for example, 0.15 g / 15 40.25 mm 2 , 0.16 g / 15 40.25 mm 2 , 0.17 g / 15 40.25 mm 2 , 0.18 g / 15 40.25 mm 2 , 0.19 g / 15 40.25 mm 2 , or other unlisted values within the range of 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 .

[0116] In some embodiments, the areal density of the negative electrode film layer is 0.15 g / 15 40.25 mm 2 to 0.165 g / 15 40.25 mm 2 .

[0117] The battery monomer provided in the present application can improve the energy density of the battery when the coating areal density of the negative electrode film is within the above range, and can also avoid the influence of thick coating on the electrochemical performance, thereby improving the fast-charging performance of the battery.

[0118] In some embodiments, the negative electrode film layer includes a negative electrode active material.

[0119] In some embodiments, the average particle size Dv50 of the negative active material is 8 μm to 15 μm, for example 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or other unlisted values within the range of 8 μm to 15 μm. In some embodiments, the negative active material comprises graphite.

[0120] As used herein, "average particle size Dv50" refers to the particle size corresponding to the cumulative volume distribution percentage of 50% from the small particle size side in the particle size distribution of the particles. The determination method can refer to GB / T 19077-2016 / ISO 13320:2009, and is determined by using a Malvern 2000 (MasterSizer 2000) laser particle size analyzer.

[0121] In the battery cell provided in the present application, when the particle size of the negative active material (for example, graphite) is within the above range, the specific surface area is large, the migration channel of lithium ions between the graphite layers is increased, the migration path is shortened, thereby accelerating the embedding and stripping speed of lithium ions between the graphite layers, so that the battery cell has good fast charging performance; at the same time, when the particle size of the negative active material (for example, graphite) is within the above range, the direct current internal resistance of the battery cell can also be improved, thereby reducing the heat generation of the battery, so that the battery has good safety performance.

[0122] In some embodiments, the average particle size Dv50 of the negative active material is 9.5 μm to 11.5 μm, for example 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, or other unlisted values within the range of 9.5 μm to 11.5 μm.

[0123] When the particle size of the negative active material (for example, graphite) is within the above range, the fast charging performance and the direct current internal resistance of the battery can be further improved, and at the same time, the battery has good cycle performance.

[0124] In some embodiments, the graphitization degree of the negative active material is 90% to 95%.

[0125] In some embodiments, the graphitization degree of the negative active material is 92% to 95%.

[0126] When the graphitization degree of the negative active material is within the above range, the capacity can be further improved.

[0127] As used herein, "graphitization degree" refers to an index for measuring the degree of carbon atoms forming a close-packed hexagonal graphite crystal structure, which can be tested using an X-ray diffractometer (such as a Bruker D8 Discover), with reference to JIS K0131-1996, JB / T 4220-2011, to obtain the average interlayer spacing d 002 of the (002) crystal plane in the crystal structure of the carbon material, and then calculate the graphitization degree according to the formula g = (0.344 - d 002 ) / (0.344 - 0.3354) x 100%. In the above formula, d 002 is the average interlayer spacing of the (002) crystal plane in the crystal structure of the carbon material, expressed in nanometers (nm).

[0128] In some embodiments, the negative electrode film layer includes at least two layers of negative electrode active material layers. In some embodiments, the negative electrode film layer includes a first negative electrode active material layer disposed on the surface of the negative electrode current collector and a second negative electrode active material layer disposed on the side of the first negative electrode active material layer away from the negative electrode current collector, the negative electrode active material in the first negative electrode active material layer includes a first artificial graphite, and the negative electrode active material in the second negative electrode active material layer includes a second artificial graphite, the average particle size Dv50 of the first artificial graphite being greater than the average particle size Dv50 of the second artificial graphite.

[0129] In some embodiments, the average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm, such as 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or other unlisted values within the range of 11 μm to 15 μm.

[0130] In some embodiments, the average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm, such as 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or other unlisted values within the range of 8 μm to 15 μm.

[0131] In some embodiments, the average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm, such as 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, or other unlisted values within the range of 9.5 μm to 11.5 μm.

[0132] The battery cell provided in the present application can further improve the kinetic performance of the battery when the above-mentioned double-layer coating scheme is used in the negative electrode film layer.

[0133] In some embodiments, the negative electrode film layer can further optionally comprise a binder. The binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0134] In some embodiments, the negative electrode film layer can further optionally comprise a conductive agent. The conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0135] In some embodiments, the negative electrode film layer can further optionally comprise other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc.

[0136] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be used. The composite current collector can comprise a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (e.g., a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0137] In some embodiments, the thickness of the negative electrode current collector is 4 μm to 6 μm, such as 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, etc., or other unlisted values within the range of 4 μm to 6 μm.

[0138] In some embodiments, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 12 to 20, such as 12, 13, 14, 15, 16, 17, 18, 19, 20, etc., or other unlisted values within the range of 12 to 20.

[0139] In some embodiments, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 13 to 20.

[0140] In some embodiments, the single-side thickness of the negative electrode film layer corresponds to the single-side thickness of the negative electrode film layer of a battery cell in a 0% SOC state, wherein the battery cell in the 0% SOC state refers to a battery cell discharged at 1 / 3 C to 2.0 V and then discharged at 0.05 C to 2.0 V. In the battery cell provided herein, when the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is within the above range, the energy density and the fast-charging performance of the battery can be further improved.

[0141] In some embodiments, as shown in FIG. 3, the current collector 11 includes a current collecting portion 11a and at least two tabs 11b disposed on the same side of the current collecting portion 11a, the tabs 11b extending from the current collecting portion 11a along a first direction F1, wherein the distance between the center lines L of two adjacent tabs 11b is 10 mm to 350 mm, the center lines L being parallel to the first direction F1, for example, 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 350 mm, or other values not listed in the range of 10 mm to 350 mm.

[0142] In some embodiments, the distance between the center lines L of two adjacent tabs 11b is 20 mm to 330 mm, the center lines L being parallel to the first direction F1, for example, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 330 mm, or other values not listed in the range of 20 mm to 330 mm.

[0143] In some embodiments, as shown in FIGS. 3 and 4, the current collector 11 can be a positive current collector, and the tabs 11b can be positive tabs 111b.

[0144] In some embodiments, as shown in FIGS. 3 and 4, the current collector 11 can be a negative current collector, and the tabs 11b can be negative tabs 112b.

[0145] In some embodiments, the negative current collector includes a negative current collecting portion and at least two negative tabs disposed on the same side of the negative current collecting portion, the negative tabs extending from the negative current collecting portion along a first direction. In some embodiments, the distance between the center lines of two adjacent negative tabs is 10 mm to 350 mm, the center lines being parallel to the first direction, for example, 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 350 mm, or other values not listed in the range of 10 mm to 350 mm.

[0146] In some embodiments, the distance between the center lines of two adjacent negative tabs is 20 mm to 330 mm, the center lines being parallel to the first direction, for example 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 330 mm, or other unlisted values within the range of 20 mm to 330 mm.

[0147] In some embodiments, as shown in FIG. 3, the center line L refers to the axis of symmetry passing through the midpoint of the tab 11b along the length direction of the current collector 11, and the center line L is parallel to the first direction F1. In some embodiments, the size of each tab 11b along the length direction of the current collector 11 is equal.

[0148] In some embodiments, as shown in FIG. 3, the distance between the center lines L of two adjacent tabs 11b includes S1 or S2, where S1 and S2 can be equal (in which case the adjacent tabs are equally spaced), or S1 and S2 can not be equal (in which case the adjacent tabs are not equally spaced).

[0149] The battery cell provided in the present application can further improve the overcurrent capacity and the direct current resistance of the battery cell, thereby further reducing the heat generation of the battery and improving the safety performance of the battery when the positive and negative current collectors include at least two tabs with the above structural characteristics.

[0150] In some embodiments, the negative electrode tab can be prepared by dispersing the above-mentioned components for preparing the negative electrode tab, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after drying, cold pressing, and other processes, the negative electrode tab is obtained.

[0151] In some embodiments, the compaction density of the negative electrode tab is 1.3 g / cm 3 to 1.6 g / cm 3 , for example 1.3 g / cm 3 , 1.4 g / cm 3 , 1.5 g / cm 3 , 1.6 g / cm 3 , or other unlisted values within the range of 1.3 g / cm 3 to 1.6 g / cm 3 .

[0152] In some embodiments, the compaction density of the negative electrode tab is 1.35 g / cm 3 to 1.55 g / cm3 for example 1.35 g / cm 3 , 1.40 g / cm 3 , 1.45 g / cm 3 , 1.50 g / cm 3 , 1.55 g / cm 3 , or other unlisted values within the range of 1.35 g / cm 3 to 1.55 g / cm 3 .

[0153] In some embodiments, the compaction density of the negative electrode tab corresponds to the compaction density of the negative electrode film layer of the battery cell in the 0% SOC state, wherein the battery cell in the 0% SOC state refers to a battery cell discharged to 2.0 V at 1 / 3 C and then discharged to 2.0 V at 0.05 C. As used herein, the “compaction density” of the tab is: compaction density = areal density / (tab thickness - current collector thickness), which can be determined according to GB / T 24533-2009.

[0154] When the compaction density of the negative electrode tab is within the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0155] [Positive electrode tab]

[0156] In some embodiments, the positive electrode tab includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. As an example, the positive electrode current collector has two opposite surfaces in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0157] In some embodiments, the areal density of the positive electrode film layer on a single surface is 0.33 g / 15 40.25 mm 2 to 0.4 g / 15 40.25 mm 2 , for example 0.33 g / 15 40.25 mm 2 , 0.34 g / 15 40.25 mm 2 , 0.35 g / 15 40.25 mm 2 , 0.36 g / 15 40.25 mm 2 , 0.37 g / 15 40.25 mm 2 , 0.38 g / 15 40.25 mm 2 , 0.39 g / 15 40.25 mm 2 , 0.4 g / 15 40.25 mm 2 , or other unlisted values within the range of 0.33 g / 15 40.25 mm 2 to 0.4 g / 15 40.25 mm 2other unlisted values within the ranges.

[0158] In some embodiments, the areal density of the positive electrode film layer on a single side is 0.335 g / 15 40.25 mm 2 to 0.38 g / 15 40.25 mm 2 .

[0159] The battery cell provided in the present application can improve the energy density of the battery when the coating areal density of the positive electrode film layer is within the above range, and can also avoid the influence of thick coating on the electrochemical performance, thereby taking into account the improvement of the fast charging performance of the battery.

[0160] In some embodiments, the positive electrode film layer comprises a positive electrode active material.

[0161] In some embodiments, the positive electrode active material comprises a lithium-containing phosphate with an olivine structure.

[0162] In some embodiments, the lithium-containing phosphate with an olivine structure has a general formula as shown in Formula I,

[0163] Li x A y Me a M b P 1-c X c Y z Formula I,

[0164] wherein 0.1≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A comprises one or more of Na, K, Mg; Me comprises one or more of Mn, Fe, Co, Ni; M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X comprises one or more of S, Si, Cl, B, C, N; Y comprises one or more of O, F.

[0165] As used herein, "the lithium-containing phosphate composition of olivine structure represented by the general formula as shown in Formula I" is not limited to the substance represented by the general formula, but also includes other substances formed by further appropriately modifying the substance on the basis of the general formula, which are not limited herein. The use of "general formula" is only for the convenience of description, and is not intended to limit the present application. It can be understood that new materials or substances obtained by appropriately modifying the listed positive electrode active material are also within the scope of the positive electrode active material, and the aforementioned appropriate modification refers to acceptable modification of the positive electrode active material, and non-limiting examples include coating modification.

[0166] When the lithium-containing phosphate as the positive electrode active material has the chemical general formula described above, the energy density of the battery can be further improved.

[0167] In some embodiments, M includes one or more of Al, Ti, V, and Mg.

[0168] In some embodiments, the positive electrode active material contains Al element, and the mass content of the Al element is 0.001% to 0.05%, optionally 0.01% to 0.05%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, or other values not listed in the range of 0.001% to 0.05%, based on the total mass of the positive electrode active material.

[0169] In some embodiments, the positive electrode active material contains Ti element, and the mass content of the Ti element is 0.001% to 0.03%, optionally 0.01% to 0.03%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.02%, 0.03%, or other values not listed in the range of 0.001% to 0.03%, based on the total mass of the positive electrode active material.

[0170] In some embodiments, the positive electrode active material contains V element, and the mass content of the V element is 0.001% to 0.3%, optionally 0.1% to 0.3%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, or other values not listed in the range of 0.001% to 0.3%, based on the total mass of the positive electrode active material.

[0171] In some embodiments, the positive electrode active material contains Mg element, the mass content is 0.001% to 0.01%, based on the total mass of the positive electrode active material, which can be 0.001%, 0.002%, 0.005%, 0.01%, or other unlisted values within the range of 0.001% to 0.01%, based on the total mass of the positive electrode active material.

[0172] When the lithium-containing phosphate as the positive electrode active material contains Al, Ti, V, Mg and other elements, the structural stability of the material can be further improved, and the cycle performance can be improved.

[0173] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the olivine-structured lithium-containing phosphate contains first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm.

[0174] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the olivine-structured lithium-containing phosphate contains first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm, such as 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, or other unlisted values within the range of 0.05 μm to 0.3 μm.

[0175] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the olivine-structured lithium-containing phosphate contains second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, or other unlisted values within the range of 1 μm to 3 μm.

[0176] In some embodiments, since the first lithium-containing phosphate and the second lithium-containing phosphate have been sufficiently mixed when preparing the slurry and uniformly coated on the current collector to form the positive electrode film layer, the cross section of the positive electrode tab along the thickness direction can represent the particle size and distribution of the lithium-containing phosphate in the entire tab. When selecting the cross section, the cross section in the middle of the tab, which is relatively flat, is preferred, so that the distribution of the lithium-containing phosphate therein can be more clearly observed.

[0177] In some embodiments, the "longest diameter" refers to: cutting the positive electrode sheet including the lithium-containing phosphate particles along the thickness direction of the sheet to expose the longitudinal section of the positive electrode film layer; and determining the longest diameter of the lithium-containing phosphate particles by scanning electron microscopy (SEM) test on the longitudinal section of the positive electrode film layer. Specifically, the maximum value of the distance between any two points on the outer edge line of the lithium-containing phosphate particles is the "longest diameter" of the particles. In some embodiments, the longitudinal section of the sheet along the thickness direction is shown in FIG. 2, which shows the longest diameter of the single particles of the first lithium-containing phosphate particles (0.05-0.3 pm) and the shortest diameter of the single particles of the second lithium-containing phosphate particles (1-3 pm).

[0178] In the battery cell provided by the present application, when the positive active material contains lithium-containing phosphate particles with a longest diameter of 0.05-0.3 pm, the direct current internal resistance of the battery cell can be further improved, thereby further reducing the heat generation of the battery, and the battery has excellent safety performance.

[0179] In the battery cell provided by the present application, when the positive active material contains lithium-containing phosphate particles with a longest diameter of 0.05-0.3 pm and lithium-containing phosphate particles with a longest diameter of 1-3 pm, the compaction density of the electrode sheet can be effectively improved by size grading, thereby making the battery cell have a higher energy density.

[0180] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

[0181] When the number of the first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 pm is greater than the number of the second lithium-containing phosphate particles with a longest diameter of 1-3 pm, the direct current internal resistance and the fast charging performance of the battery can be further improved.

[0182] It should be noted that the first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 pm are one of the positive active materials of the battery cell provided by the present application, and the particle size range of 0.05-0.3 pm is a characteristic parameter of the material itself.

[0183] The second lithium-containing phosphate particles with a longest diameter of 1-3 pm are one of the positive active materials of the battery cell provided by the present application, and the particle size range of 1-3 pm is a characteristic parameter of the material itself.

[0184] The two kinds of lithium-containing phosphate particle materials with different size ranges can be mixed according to actual needs by those skilled in the art.

[0185] In some embodiments, the positive electrode film layer further optionally comprises a positive electrode conductive agent. The present application does not have a particular limitation on the kind of the positive electrode conductive agent, and as an example, the positive electrode conductive agent comprises at least one of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0186] In some embodiments, the positive electrode film layer further optionally comprises a positive electrode binder. The present application does not have a particular limitation on the kind of the positive electrode binder, and as an example, the positive electrode binder can comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin.

[0187] In some embodiments, the positive electrode current collector can adopt a metal foil or a composite current collector. As an example of the metal foil, an aluminum foil can be adopted. The composite current collector can comprise a polymer material base layer and a metal material layer formed on at least one side surface of the polymer material base layer. As an example, the metal material can comprise at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can comprise at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0188] In some embodiments, the thickness of the positive electrode current collector is 10 μm to 15 μm, for example, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or other unlisted values within the range of 10 μm to 15 μm.

[0189] In some embodiments, the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 5 to 12, for example, 5, 6, 7, 8, 9, 10, 11, 12, or other unlisted values within the range of 5 to 12.

[0190] In some embodiments, the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 6 to 10.

[0191] In the battery cell provided by the present application, when the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is within the above range, the thickness of the current collector is within a suitable range, so that the problem of excessive thickness causing loss of energy density is avoided, and the problem of excessive thinness causing poor flow capacity and low tensile strength leading to cracking of the electrode sheet is avoided, further taking into account the improvement of the energy density and fast charging performance of the battery.

[0192] In some embodiments, the positive current collector comprises a positive current collecting portion and at least two positive tabs disposed on the same side of the positive current collecting portion, the positive tabs extending from the positive current collecting portion along a first direction, wherein the distance between the center lines of two adjacent positive tabs is 10-350 mm, the center lines being parallel to the first direction, for example, 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 350 mm, or other values not listed in the range of 10-350 mm.

[0193] In some embodiments, the distance between the center lines of two adjacent positive tabs is 20-330 mm, for example, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 330 mm, or other values not listed in the range of 20-330 mm.

[0194] The battery cell provided in the present application can further improve the overcurrent capacity and the direct current resistance of the battery cell when the positive and negative current collectors comprise at least two tabs with the above structural characteristics, thereby further reducing the heat generation of the battery and improving the safety performance of the battery.

[0195] In some embodiments, the size of the positive film layer along the first direction is W1 mm, and the size of the negative film layer along the first direction is W2 mm, wherein W2 > W1, and the difference between W2 and W1 is 3-5 mm, for example, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5 mm, or other values not listed in the range of 3-5 mm.

[0196] During the cycle process of the battery, lithium ions that cannot be timely embedded in the negative electrode may form lithium dendrites on the surface of the negative electrode, deteriorating the cycle performance of the battery. In the battery cell provided in the present application, when the size W2 of the negative film layer and the size W1 of the positive film layer have the above relationship, the formation of lithium dendrites on the surface of the negative electrode can be improved, thereby simultaneously making the battery have good cycle performance.

[0197] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector, and then drying, cold-pressing and the like to obtain the positive electrode sheet.

[0198] In some embodiments, the positive electrode sheet has a compacted density of 2.3 g / cm 3 to 2.6 g / cm 3 , such as 2.30 g / cm 3 , 2.35 g / cm 3 , 2.40 g / cm 3 , 2.45 g / cm 3 , 2.50 g / cm 3 , 2.55 g / cm 3 , 2.60 g / cm 3 , or other unlisted values within the range of 2.3 g / cm 3 to 2.6 g / cm 3 .

[0199] In some embodiments, the positive electrode sheet has a compacted density of 2.4 g / cm 3 to 2.55 g / cm 3 .

[0200] When the compacted density of the positive electrode sheet is within the above-mentioned range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0201] In some embodiments, the compacted density of the positive electrode sheet corresponds to the compacted density of the positive electrode film layer of the battery cell in the 0% SOC state, wherein the battery cell in the 0% SOC state refers to a battery cell discharged at 1 / 3C to 2.0V and then discharged at 0.05C to 2.0V.

[0202] [Electrolyte]

[0203] The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet. For example, the electrolyte can be in a liquid state, a solid state or a gel state.

[0204] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and an organic solvent.

[0205] In the embodiments of the present application, the types and contents of the organic components in the electrolyte are in the meanings known in the art, and can be detected by using the devices and methods known in the art, for example, the composition of the electrolyte can be detected by liquid chromatography, gas chromatography, ion chromatography, liquid nuclear magnetic method, etc. For example, the organic components in the electrolyte can be qualitatively and quantitatively analyzed by gas chromatography according to GB / T 9722-2006 “General method for gas chromatography of chemical reagents”.

[0206] In the embodiments of the present application, the test sample can be the freshly prepared electrolyte, or the free electrolyte obtained from the battery after the battery is fully discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC).

[0207] In the embodiments of the present application, the types and contents of the inorganic components / lithium salt concentration in the electrolyte are in the meanings known in the art, and can be detected by using the devices and methods known in the art, for example, the inorganic components / lithium salt concentration in the electrolyte can be qualitatively or quantitatively analyzed by ion chromatography according to the standard JY / T020-1996 “General method for ion chromatography analysis”. In the embodiments of the present application, the test sample can be the freshly prepared electrolyte, or the free electrolyte obtained from the battery after the battery is fully discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC), and the ion chromatography analysis method is used for detection.

[0208] In some embodiments, the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

[0209] In the battery cell provided by the present application, when the organic solvent of the above type is used in the electrolyte, the kinetic performance of the battery can be further improved.

[0210] In some embodiments, the organic solvent includes a linear carboxylic acid ester, and the mass fraction of the linear carboxylic acid ester in the total mass of the electrolyte is 40% to 75%, for example, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, etc., or other values in the range of 40% to 75% not listed.

[0211] In some embodiments, the linear carboxylic acid ester has a general structure of R1-COO-R2, wherein R1 and R2 each independently includes one or more of C1-C5 alkyl and C1-C5 halogenated alkyl.

[0212] In some embodiments, the linear carboxylic acid ester includes one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

[0213] When the electrolyte adopts the linear carboxylic acid ester of the above type and mass ratio as the organic solvent, the linear carboxylic acid ester can effectively improve the conductivity of the electrolyte, thereby further improving the fast-charging performance of the battery.

[0214] In some embodiments, the organic solvent comprises a carbonate solvent, the carbonate solvent comprises a linear carbonate and a cyclic carbonate, the mass ratio of the linear carbonate is 10% to 40%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or other values not listed in the range of 10% to 40%, based on the total mass of the electrolyte.

[0215] In some embodiments, the cyclic carbonate comprises one or more of ethylene carbonate and propylene carbonate, and the linear carbonate comprises one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0216] In some embodiments, the linear carbonate comprises dimethyl carbonate, and the mass ratio of the dimethyl carbonate is 5% to 15%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or other values not listed in the range of 5% to 15%, based on the total mass of the electrolyte.

[0217] When the electrolyte adopts the carbonate of the above type and mass ratio as the organic solvent, the side reactions and gas generation during the cycle of the battery can be improved, thereby simultaneously making the battery have good cycle performance.

[0218] In some embodiments, the organic solvent comprises dimethyl carbonate and linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 2.0 to 7.0, for example, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, or other values not listed in the range of 2.0 to 7.0.

[0219] In some embodiments, the organic solvent comprises dimethyl carbonate and linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.0.

[0220] When the electrolyte simultaneously adopts the dimethyl carbonate and linear carboxylic acid ester of the above mass ratio as the organic solvent, the combination of the two solvents can further improve the fast-charging performance and cycle performance of the battery.

[0221] In some embodiments, the electrolyte further comprises a lithium salt, such as at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro-oxalato-borate, lithium bis-oxalato-borate, lithium difluoro-bis-oxalato-phosphate, and lithium tetrafluoro-oxalato-phosphate.

[0222] In some embodiments, the lithium salt has a mass fraction of 13% to 20%, such as 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or other unlisted values within the range of 13% to 20%, based on the total mass of the electrolyte.

[0223] In some embodiments, the lithium salt comprises at least two of lithium hexafluorophosphate LiPF6 and a fluorine-containing sulfonylimide salt, such as one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis-trifluoromethanesulfonylimide LiTFSI.

[0224] Lithium hexafluorophosphate is less likely to produce gas during cycling, which can further improve the cycling performance of the battery. A fluorine-containing sulfonylimide salt has strong dissociation ability, which can further improve the fast-charging performance of the battery.

[0225] In some embodiments, the lithium salt comprises lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonylimide LiFSI.

[0226] In some embodiments, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfonylimide LiFSI in the electrolyte is 1.2:1 to 2:1, such as 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, or other unlisted values within the range of 1.2:1 to 2:1.

[0227] When lithium hexafluorophosphate and lithium bisfluorosulfonylimide in the above mass ratio range are used simultaneously in the electrolyte, the fast-charging performance and the cycling performance of the battery can be further improved.

[0228] In some embodiments, the electrolyte further comprises an additive. For example, the additive can comprise a negative electrode film-forming additive, a positive electrode film-forming additive, and / or an additive capable of improving certain performance of the battery, such as an additive capable of improving the overcharge performance of the battery, an additive capable of improving the high-temperature or low-temperature performance of the battery, and / or the like.

[0229] In some embodiments, the electrolyte comprises a carbonate additive, such as fluoroethylene carbonate FEC and vinylene carbonate VC.

[0230] In some embodiments, the mass percentage of the carbonate additive in the electrolyte is 0.5% to 7%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 6.5%, 7%, or the like, or other values not listed in the range of 0.5% to 7%, based on the total mass of the electrolyte.

[0231] In the battery cell provided by the present application, the carbonate additive, for example, fluoroethylene carbonate and vinylene carbonate, having a mass percentage in the above range is further added to the electrolyte. The carbonate additive can form an SEI film on the surface of the negative electrode, thereby reducing the side reaction between the electrode and the electrolyte, and further improving the cycle performance of the battery.

[0232] In some embodiments, the electrolyte includes vinylene carbonate VC, and the mass percentage of the vinylene carbonate VC in the electrolyte is 0.5% to 2%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or the like, or other values not listed in the range of 0.5% to 2%, based on the total mass of the electrolyte.

[0233] When the vinylene carbonate having the mass percentage in the above range is added to the electrolyte as an additive, the SEI film formed by the vinylene carbonate is stable, which is beneficial to further improving the cycle performance of the battery.

[0234] In some embodiments, the electrolyte includes fluoroethylene carbonate FEC, and the mass percentage of the fluoroethylene carbonate FEC in the electrolyte is 0.1% to 1%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or the like, or other values not listed in the range of 0.1% to 1%, based on the total mass of the electrolyte.

[0235] When the fluoroethylene carbonate having the mass percentage in the above range is added to the electrolyte as an additive, the SEI film formed by the fluoroethylene carbonate has low impedance, which is beneficial to further improving the fast-charging performance of the battery.

[0236] [Separator]

[0237] In some embodiments, the battery cell further includes a separator. The type of the separator is not particularly limited in the present application, and any known porous structure separator having good chemical stability and mechanical stability can be used.

[0238] In some embodiments, the material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0239] [Battery cell]

[0240] In some embodiments, the positive electrode tab, the negative electrode tab, and the separator film can be used to make an electrode assembly through a winding process or a stacking process.

[0241] In some embodiments, the positive current collector, the separator, the negative current collector, and the separator are sequentially stacked and wound together. After winding, the positive electrode tabs 111b of the positive current collector are aligned and stacked, and the negative electrode tabs 112b of the negative current collector are aligned and stacked, as shown in FIG. 4.

[0242] In some embodiments, the battery cell further comprises a top cover comprising electrode terminals of opposite polarity for electrically connecting with the positive electrode tabs or the negative electrode tabs.

[0243] In some embodiments, as shown in FIG. 4, the battery cell 10 further comprises a top cover 13 comprising two electrode terminals 131 of opposite polarity, one of which is a positive electrode terminal 131 for electrically connecting with the positive electrode tabs 111b, and the other is a negative electrode terminal 131 for electrically connecting with the negative electrode tabs 112b.

[0244] After winding, the positive electrode tabs 111b are aligned and stacked, having a large connection area, so that the positive electrode tabs 111b can be directly electrically connected with the electrode terminals 131 without the need for a connecting tab to connect the positive electrode tabs 111b with the electrode terminals 131. Similarly, after winding, the negative electrode tabs 112b are aligned and stacked, having a large connection area, so that the negative electrode tabs 112b can be directly electrically connected with the electrode terminals 131 without the need for a connecting tab to connect the negative electrode tabs 112b with the electrode terminals 131.

[0245] In conventional batteries, a connecting tab is needed to connect the electrode terminals with the electrode tabs, but this results in a loss of utilization of the electrode assembly and a reduction in the energy density of the battery. When the above structure is used in the battery cell provided in the present application, the elimination of the connecting tab can effectively solve this problem, reduce the internal resistance of the battery, and further improve the energy density and fast-charging performance of the battery.

[0246] In some embodiments, the battery cell can comprise an outer package. The outer package can be used to package the above electrode assembly and the electrolyte.

[0247] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, etc. can be listed.

[0248] In some embodiments, as shown in FIGS. 4-7, the battery cell 10 further comprises a housing 14, and the current collector 11 is disposed within the housing 14.

[0249] In some embodiments, as shown in FIGS. 4-7, the housing 14 is square, the thickness T of the housing is 30-55 mm, the width W of the housing is 150-250 mm, and the height H of the housing is 90-120 mm.

[0250] In some embodiments, the thickness T of the housing is 30-55 mm, such as 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, etc., or other unlisted values within the range of 30-55 mm.

[0251] In some embodiments, the width W of the housing is 150-250 mm, such as 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, etc., or other unlisted values within the range of 150-250 mm.

[0252] In some embodiments, the height H of the housing is 90-120 mm, such as 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, etc., or other unlisted values within the range of 90-120 mm.

[0253] In some embodiments, the battery cell is configured to have a charging time of 10-17 min from 10% SOC to 80% SOC at room temperature, such as 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, etc., or other unlisted values within the range of 10-17 min.

[0254] The battery cell provided in the present application has excellent fast charging performance.

[0255] In some embodiments, the shape of the battery cell is not particularly limited in the present application, and it can be cylindrical, square, or any other shape. For example, FIG. 8 is a battery cell 5 in a square structure as an example. Optionally, the battery cell is a lithium ion battery or a sodium ion battery.

[0256] In some embodiments, referring to FIG. 9, the outer package can include a housing 51 and a cover plate 53. The housing 51 can include a bottom plate and side plates connected to the bottom plate, which enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode tab, the negative electrode tab, and the separator film can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific actual needs.

[0257] In some embodiments, a battery device, which can be a battery module, a battery pack, an energy storage battery, etc., is provided. The above-mentioned battery cell can be assembled into a battery module, and 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.

[0258] FIG. 10 is a battery module 4 as an example. Referring to FIG. 10, in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other manner. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0259] Optionally, the battery module 4 can further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0260] 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.

[0261] FIGS. 11 and 12 are a battery pack 1 as an example. Referring to FIGS. 11 and 12, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be arranged on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0262] [Electric device]

[0263] In addition, the application also provides a power utilization device comprising at least one of the battery cell, the battery module or the battery pack provided by the application. The battery cell, the battery module or the battery pack can be used as a power supply of the power utilization device, and can also be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as 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.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0264] As the power utilization device, the battery cell, the battery module or the battery pack can be selected according to the use requirement thereof.

[0265] FIG. 13 is a power utilization device 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 cell for the power utilization device, the battery pack or the battery module can be used.

[0266] In some embodiments, the power utilization device comprises a vehicle, and the length direction of the electrode assembly is arranged along the running direction of the vehicle.

[0267] The device as another example can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and the battery cell can be used as a power supply.

[0268] Embodiments

[0269] Hereinafter, the embodiments of the application are described. The embodiments described below are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application. If the specific technology or condition is not indicated in the embodiments, the technology or condition described in the literature in the art or according to the product instruction is used. If the reagent or instrument used is not indicated by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0270] Embodiment 1

[0271] 1) Negative electrode tab

[0272] The negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber and the thickening agent sodium carboxymethyl cellulose were mixed according to the mass ratio of 96:1:2:1, and then the solvent deionized water was added and stirred to form a negative electrode slurry. The negative electrode slurry was uniformly coated on the negative electrode current collector copper foil, and then dried and cold-pressed to obtain a negative electrode tab; wherein the thickness of the negative electrode current collector copper foil was 4.5 μm, the single-sided area density of the negative electrode tab was 0.155 g / 1540 mm 2 , and the compacted density of the negative electrode tab was 1.47 g / cm 3The size of the positive film layer along the first direction is 92 mm; the volume particle size Dv50 of the artificial graphite is 11 pm, and the graphitization degree is 94.1%.

[0273] 2) Positive electrode tab

[0274] The positive electrode active material lithium iron phosphate (LFP), the binder polyvinylidene fluoride, and the conductive agent acetylene black are mixed in a ratio of 97:2:1, and then a solvent N-methyl pyrrolidone (NMP) is added to stir into a positive electrode slurry; the positive electrode slurry is uniformly coated on a positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode tab is obtained. The thickness of the positive electrode current collector aluminum foil is 13 pm, and the single-sided area density of the positive electrode tab is 0.341 mg / 1540 mm 2 , and the tap density of the positive electrode tab is 2.51 g / cm 3 . The size of the positive film layer along the first direction is 88.5 mm; the positive electrode active material contains first lithium-containing phosphate particles with a longest diameter of 0.3 pm-1 pm and second lithium-containing phosphate particles with a longest diameter of 3 pm-5 pm; in a longitudinal cross section of the positive electrode tab, at least an arbitrary region containing 100 olivine structure lithium-containing phosphate particles is selected, and in the arbitrary region, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

[0275] 3) Electrolyte

[0276] Dimethyl carbonate (DMC), ethyl acetate (EA), ethylene carbonate (EC), and methyl ethyl carbonate (EMC) are uniformly mixed in a mass ratio of 10:50:35:5 to obtain an electrolyte solvent. Lithium hexafluorophosphate (LiPF6) and lithium bisfluorosulfonylimide (LiFSI) are included as lithium salts, and are fully stirred until they are completely dissolved. The additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are included in a mass percentage of 0.7% and 0.3%, respectively, relative to the total mass of the electrolyte. Based on the total mass of the electrolyte, the mass percentage of lithium hexafluorophosphate (LiPF6) is 8.9%, and the mass percentage of lithium bisfluorosulfonylimide LiFSI is 4.6%. The lithium ion conductivity of the electrolyte is 14.5 mS / cm.

[0277] 4) Separation film

[0278] A commercially available polyethylene microporous film with a thickness of 7 pm and an average pore size of 80 nm is used as the separator.

[0279] 5) Battery cell

[0280] The positive electrode sheet and the negative electrode sheet are cut to have tabs, the distance between the center lines of the two adjacent tabs of the positive electrode sheet is 316 mm, and the distance between the center lines of the two adjacent tabs of the negative electrode sheet is 314 mm. The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound in sequence to obtain a wound electrode assembly, so that each layer of the electrode assembly has at least one tab. The electrode assembly is placed in an outer packaging square aluminum shell with a thickness of 50 mm, a width of 208 mm, and a height of 103 mm, and after drying, an electrolyte is injected. After packaging, standing, formation, aging, secondary packaging, and capacity processes, a battery monomer is obtained, and the tabs of the battery monomer are connected to the cover plate.

[0281] Examples 2-3

[0282] The battery monomers of Examples 2-3 are basically similar to Example 1, except that the widths W1 and W2 of the positive electrode film layer and the negative electrode film layer are adjusted to adjust the value of W2-W1, as shown in Tables 1-4.

[0283] Examples 4-6

[0284] The battery monomers of Examples 4-6 are basically similar to Example 1, except that the single-sided negative electrode film layer area density and the single-sided positive electrode film layer area density are adjusted, as shown in Tables 1-4.

[0285] Examples 7-10

[0286] The battery monomers of Examples 7-10 are basically similar to Example 1, except that the types or contents of organic solvents and lithium salts in the electrolyte are changed, as shown in Tables 1-4.

[0287] Example 11

[0288] The battery monomers of Example 11 are basically similar to Example 1, except that the negative active material uses double-layer coating, and the method is as follows: the particle size Dv50 of 13 μm artificial graphite is used as the lower layer, and the particle size Dv50 of 10 μm artificial graphite is used as the upper layer, which are uniformly coated on the negative current collector copper foil, dried and cold-pressed to obtain a negative electrode sheet. See Tables 1-4 for details.

[0289] Comparative Examples 1-2

[0290] Comparative Examples 1-2 are basically similar to Example 1, except that the widths W1 and W2 of the positive electrode film layer and the negative electrode film layer are adjusted to adjust the value of W2-W1, as shown in Tables 1-4.

[0291] Comparative Examples 3-4

[0292] Comparative Examples 3-4 are basically similar to Example 1, except that the single-sided area densities of the positive electrode sheet and the negative electrode sheet are different, as shown in Tables 1-4.

[0293] I. Performance Test

[0294] 1. DC Internal Resistance

[0295] The DC internal resistance DCR test of the battery cell can refer to the method in GB / T31467 "HEV High Power Lithium-ion Power Battery Performance Test Specification". For example, at room temperature, the battery cell is charged to 3.65V at a constant current of 0.33C, and then rested for 1 min, and then charged to 3.65V at a constant current of 0.1C, and then rested for 30 min, and then discharged to 2.0V at a constant current of 0.33C, and then the discharge capacity A0 is recorded, in Ah, and then the battery cell is charged at a constant current of 0.33C for 0.5A0 Ah, and the SOC is adjusted to 50%. After the battery cell is placed at 25°C for 2h, it is discharged at a constant current of 3C for 10s, and the ΔU discharge and the ΔI discharge are recorded, and the discharge DCR data of the lithium-ion battery is calculated by the following formula: Rdischarge = ΔU discharge / ΔI discharge, wherein ΔU discharge represents the voltage change within 10s at the beginning of discharge, and ΔI discharge represents the current value within 10s at the beginning of discharge.

[0296] 2. Charge Time at 10% to 80% SOC

[0297] Charging time test: ① Voltage calibration: 1) The positive electrode sheet, negative electrode sheet, separator and electrolyte in the example or comparative example were prepared into a stacked three-electrode battery, which was placed at 25 °C for 30 min; 2) After the battery monomer was charged to the charging cut-off voltage 3.65 V at 0.33 C at 25 °C, constant voltage charging was continued at the charging cut-off voltage until the current was 0.05 C, and the charging cut-off (wherein C represents the rated capacity of the battery monomer); 3) 25 °C for 1 h; 4) the battery monomer was discharged to the discharge cut-off voltage 2.5 V at 0.33 C at 25 °C, and the total discharge capacity C0 discharged by the battery monomer was recorded; 5) 25 °C for 1 h. ② Normal temperature charging test: 1) The positive electrode sheet, negative electrode sheet, separator and electrolyte in the example or comparative example were prepared into a stacked three-electrode battery, which was placed for 30 min; 2) 0.33 C0 direct current discharge to the discharge cut-off voltage 2.5 V, which corresponds to 0% SOC at this time; 3) 5 min; 4) 5C0 constant current charging to the negative electrode potential 0 V, reading the capacity C1 at this time, which corresponds to C1 / C0 SOC at this time; 5) 5 min; 6) 4.5C0 constant current charging to the negative electrode potential 0 V, reading the capacity C2 at this time, which corresponds to C2 / C0 SOC at this time; 7) 5 min; 8) 4C0 constant current charging to the negative electrode potential 0 V, reading the capacity C3 at this time, which corresponds to C3 / C0 SOC at this time; 9) 5 min; 10) 3C0 constant current charging to the negative electrode potential 0 V, reading the capacity C4 at this time, which corresponds to C4 / C0 SOC at this time; 11) 5 min; 12) 2C0 constant current charging to the negative electrode potential 0 V, reading the capacity C5 at this time, which corresponds to C5 / C0 SOC at this time; 13) 5 min; 14) 1C0 constant current charging to the negative electrode potential 0 V, reading the capacity C6 at this time, which corresponds to C6 / C0 SOC at this time; 15) 5 min; 16) 0.8C0 constant current charging to the negative electrode potential 0 V, reading the capacity C7 at this time, which corresponds to C7 / C0 SOC at this time; 17) 5 min; 18) 0.5C0 constant current charging to the negative electrode potential 0 V, reading the capacity C8 at this time, which corresponds to C8 / C0 SOC at this time; 19) 5 min; 20) 0.33C0 constant current charging to the negative electrode potential 0 V, reading the capacity C9 (also C0) at this time, which corresponds to 100% SOC. The total charging time from 10% SOC to 80% SOC charging process is obtained by adding the charging time.

[0298] 3, volumetric energy density

[0299] The battery monomer was discharged at 0.33C to 2.5V at 25°C, rested for 5min, charged to the upper limit cut-off voltage 3.65V at 0.33C, then charged to a current of 0.05C at constant voltage, rested for 5min; discharged to the cut-off voltage 2.5V at 0.33C, recorded the discharge capacity at this time and obtained the discharge energy E0. The volumetric energy density (Wh / L) = discharge energy E0 / monomer volume (L).

[0300] 4. Cycle performance

[0301] Charged to 3.65V at 0.5C charge rate, then charged to 0.05C at constant voltage at 3.65V, rested for 10min, then discharged to 2.5V at 1C discharge rate, rested for 10min, the above one charge-discharge is one cycle, until the battery capacity decays to 80% of the nominal capacity to stop testing, recorded as the cycle number @ 80% SOH.

[0302] II. Analysis of test results of each example and comparative example

[0303] The battery monomers of each example and comparative example were prepared according to the above method, and each performance parameter was measured, and the results are shown in Tables 1-5 below.

[0304] Table 1. Parameters for preparing electrode sheets

[0305] Table 2. Parameters for preparing electrode sheets

[0306] Table 3. Parameters for preparing electrolyte

[0307] Table 4. Parameters for preparing electrolyte

[0308] Table 5. Battery performance parameters

[0309] In the battery monomers of Examples 1-11, the area density of the single-face positive electrode film layer was 0.33g / 1540.25mm 2 to 0.4g / 1540.25mm 2 ; the area density of the single-face negative electrode film layer was 0.15g / 1540.25mm 2 to 0.19g / 1540.25mm 2 ; along the first direction, the size of the positive electrode film layer was W1mm, the size of the negative electrode film layer was W2mm, W2>W1, and the difference between W2and W1was 3mm to 5mm; therefore, the battery monomers prepared in Examples 1-11 all had excellent fast-charging performance, energy density, cycle performance, and low direct-current internal resistance.

[0310] The difference between the size W2 and W1 of the positive and negative electrode film layers of Comparative Examples 1-2 exceeds 3mm to 5mm, wherein: the difference between W2 and W1 in Comparative Example 1 is too small, and the difference between W2 and W1 in Comparative Example 2 is too large.

[0311] From the comparison of Comparative Examples 1-2 and Examples 1-11, it can be seen that when the difference between the size W2 and W1 of the positive and negative electrode film layers is less than 3mm, the cycle performance of the battery cell is deteriorated; and when the difference between the size W2 and W1 of the positive and negative electrode film layers is greater than 5mm, the energy density of the battery cell is deteriorated; therefore, the difference between the size W2 and W1 of the positive and negative electrode film layers needs to be within the range of 3mm to 5mm, so as to improve the cycle performance and energy density of the battery, and when the range is exceeded, the comprehensive performance of the battery is poor.

[0312] The area density of the positive and negative electrode film layers of Comparative Examples 3-4 respectively exceeds the range of 0.33 g / 15 40.25mm 2 to 0.4 g / 15 40.25mm 2 , 0.15 g / 15 40.25mm 2 to 0.19 g / 15 40.25mm 2 , wherein: the area density of the single-sided positive electrode film layer and the area density of the single-sided negative electrode film layer in Comparative Example 3 are too large, and the area density of the single-sided positive electrode film layer and the area density of the single-sided negative electrode film layer in Comparative Example 4 are too small.

[0313] From the comparison of Comparative Examples 3-4 and Examples 1-11, it can be seen that when the area density of the positive and negative electrode film layers is too large, the fast-charging performance, direct current resistance, and cycle performance of the battery cell are deteriorated; and when the area density of the positive and negative electrode film layers is too large, the energy density of the battery cell is deteriorated; therefore, when the area density of the positive and negative electrode film layers is within the range of 0.33 g / 15 40.25mm 2 to 0.4 g / 15 40.25mm 2 , 0.15 g / 15 40.25mm 2 to 0.19 g / 15 40.25mm 2 , the fast-charging performance, direct current resistance, cycle performance, and energy density of the battery are improved, and when the range is exceeded, the comprehensive performance of the battery is poor.

[0314] In Examples 1-3, the difference between the dimensions W2 and W1 of the positive and negative electrode films is within the range of 3 mm to 5 mm. The resulting battery cells can achieve excellent energy density, fast charging performance, cycle performance, and low DC internal resistance. Furthermore, the results show that when the difference between W2 and W1 gradually increases within the range of 3 mm to 5 mm, the battery's cycle performance, fast charging performance, and DC internal resistance are improved to some extent, but the energy density decreases to some extent. Conversely, when the difference between W2 and W1 gradually decreases within the range of 3 mm to 5 mm, the battery's energy density is improved to some extent, but the improvement in cycle performance, fast charging performance, and DC internal resistance is limited.

[0315] In Examples 1 and 4-6, the areal density of the positive and negative electrode films is 0.33 g / 1540.25 mm², respectively. 2 Up to 0.4g / 1540.25mm 2 0.15g / 1540.25mm 2 Up to 0.19g / 1540.25mm 2 Within this range, the prepared battery cells can achieve excellent energy density, fast charging performance, cycle performance, and low DC internal resistance. Furthermore, the results show that as the areal density of the positive and negative electrode films gradually decreases within the aforementioned range, the battery's cycle performance, fast charging performance, and DC internal resistance improve to some extent, but the energy density decreases to some extent; conversely, as the areal density of the positive and negative electrode films gradually increases within the aforementioned range, the battery's energy density improves to some extent, but the improvement in cycle performance, fast charging performance, and DC internal resistance is limited.

[0316] Therefore, based on the results of Examples 1-6, the difference between the dimensions W2 and W1 of the positive and negative electrode films needs to be within the range of 3mm to 5mm, and the areal densities of the positive and negative electrode films need to be 0.33g / 1540.25mm, respectively. 2 Up to 0.4g / 1540.25mm 2 0.15g / 1540.25mm 2 Up to 0.19g / 1540.25mm 2 Only when the range is within which the battery's energy density, fast charging performance, cycle performance, and DC internal resistance can be improved, thus giving the battery excellent overall performance.

[0317] In the embodiments 1, 7-10, the electrolyte is prepared by using the following formulation, and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low DC internal resistance: the organic solvent is prepared by using linear carboxylic acid ester (e.g., ethyl acetate) with a mass ratio of 40% to 75%, linear carbonate (e.g., DMC, EMC) with a mass ratio of 10% to 40%, and cyclic carbonate (e.g., ethylene carbonate) with a mass ratio of 5% to 15%, and the mass ratio of the linear carboxylic acid ester (e.g., ethyl acetate) to the cyclic carbonate (e.g., ethylene carbonate) is 2.0 to 7.0; and the lithium salt is prepared by using LiPF6 and LiFSI with a mass ratio of 13% to 20%, and the mass ratio of LiPF6 to LiFSI is 1.2:1 to 2:1.

[0318] Meanwhile, the embodiments 1, 7, and 8 show that, as the proportion of the linear carboxylic acid ester (e.g., ethyl acetate) and LiFSI in the electrolyte gradually increases, the fast charging performance and the DC internal resistance of the battery are further improved; and as the proportion of the linear carbonate (e.g., DMC) and LiPF6 in the electrolyte gradually increases, the cycle performance of the battery is further improved.

[0319] Meanwhile, the embodiments 1, 9, and 10 show that, when the organic solvent of the electrolyte only contains the linear carboxylic acid ester (e.g., ethyl acetate) and does not contain the carbonate, and the lithium salt only contains LiFSI and does not contain LiPF6, the fast charging performance and the DC internal resistance of the battery are further improved, but the cycle performance of the battery is poor; and when the organic solvent of the electrolyte only contains the linear carbonate (e.g., DMC) and does not contain the linear carboxylic acid ester, and the lithium salt only contains LiPF6 and does not contain LiFSI, the cycle performance of the battery is further improved, but the improvement in the fast charging performance and the DC internal resistance is limited. Therefore, when the electrolyte contains the linear carbonate and the linear carboxylic acid ester with the above mass ratios as the organic solvent, and contains LiPF6 and LiFSI with the above mass ratios as the lithium salt, the fast charging performance, the DC internal resistance, and the cycle performance of the battery can be further improved by the mutual matching of the various solvents and lithium salts, so that the comprehensive performance of the battery is better.

[0320] In Embodiments 1 and 11, at least one layer of graphite is included in the negative electrode film layer as the negative electrode active material, and the average particle size Dv50 thereof is in the range of 8 μm to 15 μm, and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance. In addition, from the comparison between Embodiment 1 and Embodiment 11, it can be seen that when the negative electrode film layer includes two layers of artificial graphite having different particle sizes as the negative electrode active material layer (the first negative electrode active material layer is arranged on the surface of the negative electrode current collector, and the second negative electrode active material layer is arranged on the side of the first negative electrode active material layer away from the negative electrode current collector, and the Dv50 of the first negative electrode active material layer is greater than that of the second negative electrode active material layer), the fast charging performance and the direct current internal resistance of the battery can be further improved, and the overall performance of the battery is better.

[0321] In Embodiments 1 to 11, as shown in FIG. 2, in the cross section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate salt in the positive electrode film layer includes first lithium-containing phosphate salt particles having a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate salt particles having a longest diameter of 1 μm to 3 μm, and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance.

[0322] In Embodiments 1 to 11, when the ratio of the single-face thickness of the negative electrode film layer to the thickness of the negative electrode current collector is in the range of 12 to 20, or the compaction density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3 , or the compaction density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 , the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance.

[0323] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, and other modes constructed by combining part of the configuration elements of the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, characterized by, The positive electrode tab and the negative electrode tab, The positive electrode tab comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, and the negative electrode tab comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, wherein The positive electrode film layer includes a positive electrode active material including a lithium-containing phosphate, a surface density of one face of the positive electrode film layer is 0.33 g / 15 40.25 mm 2 to 0.4 g / 15 40.25 mm 2 ; a surface density of one face of the negative electrode film layer is 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 ; The positive electrode current collector comprises a positive electrode current collecting part and at least two positive electrode tabs arranged on the same side of the positive electrode current collecting part, and the positive electrode tabs extend from the positive electrode current collecting part in a first direction; the negative electrode current collector comprises a negative electrode current collecting part and at least two negative electrode tabs arranged on the same side of the negative electrode current collecting part, and the negative electrode tabs extend from the negative electrode current collecting part in the first direction; in the first direction, the size of the positive electrode film layer is W1 mm, and the size of the negative electrode film layer is W2 mm, wherein W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm.

2. The battery cell of claim 1, the areal density of the positive electrode film layer is 0.335 g / 15 40.25 mm 2 to 0.38 g / 15 40.25 mm 2 , the areal density of the negative electrode film layer is 0.15 g / 15 40.25 mm 2 to 0.165 g / 15 40.25 mm 2 .

3. The battery cell according to claim 1 or 2, characterized in that, The compacted density of the positive electrode plate is 2.3 g / cm 3 to 2.6 g / cm 3 .

4. The battery cell according to claim 1 or 2, characterized in that, The compacted density of the positive electrode plate is 2.4 g / cm 3 to 2.55 g / cm 3 .

5. The battery cell according to any one of claims 1 to 4, characterized in that, The compacted density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 .

6. The battery cell according to any one of claims 1 to 4, characterized in that, The compacted density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm 3 .

7. The battery cell of any one of claims 1 to 6, wherein, The negative electrode film layer comprises a negative electrode active material, the average particle size Dv50 of the negative electrode active material is 8 μm to 15 μm, and the negative electrode active material comprises graphite.

8. The battery cell of claim 7, wherein, The average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm.

9. The battery cell according to claim 7 or 8, characterized in that, The graphitization degree of the negative electrode active material is 90% to 95%.

10. The battery cell according to claim 7 or 8, characterized in that, The graphitization degree of the negative electrode active material is 92% to 95%.

11. The battery cell of any one of claims 1 to 10, wherein, The negative electrode film layer comprises a first negative electrode active material layer arranged on the surface of the negative electrode current collector and a second negative electrode active material layer arranged on the side of the first negative electrode active material layer away from the negative electrode current collector, the negative electrode active material in the first negative electrode active material layer comprises a first artificial graphite, the negative electrode active material in the second negative electrode active material layer comprises a second artificial graphite, and the average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

12. The battery cell of claim 11, wherein, The average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

13. The battery cell of claim 11, wherein, The average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

14. The battery cell of claim 11, wherein, The average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

15. The battery cell of any one of claims 1 to 14, wherein, The thickness of the negative electrode current collector is 4 μm to 6 μm.

16. The battery cell of any one of claims 1 to 15, wherein, The ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 12 to 20.

17. The battery cell of any one of claims 1 to 15, wherein, The ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 13 to 20.

18. The battery cell of any one of claims 1-17, wherein, The battery monomer comprises an electrolyte, and the electrolyte comprises an organic solvent, and the organic solvent comprises a carboxylic acid ester solvent and a carbonate solvent.

19. The battery cell of claim 18, wherein, The organic solvent comprises a linear carboxylic acid ester, and the mass percentage of the linear carboxylic acid ester is 40% to 75% based on the total mass of the electrolyte.

20. The battery cell of claim 19, wherein, The linear carboxylic acid ester has a general structure of R1-COO-R2, wherein R1 and R2 each independently comprise one or more of C1-C5 alkyl and C1-C5 halogenated alkyl.

21. The battery cell of claim 20, wherein, The linear carboxylic acid ester comprises one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

22. The battery cell of any one of claims 18-21, wherein, The organic solvent comprises a carbonate solvent, and the carbonate solvent comprises a linear carbonate and a cyclic carbonate, and the mass percentage of the linear carbonate is 10% to 40% based on the total mass of the electrolyte.

23. The battery cell of claim 22, wherein, The cyclic carbonates include one or more of ethylene carbonate and propylene carbonate, and the linear carbonates include one or more of dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate.

24. The battery cell of claim 23, wherein, The linear carbonates include dimethyl carbonate, and the mass percentage of the dimethyl carbonate in the total mass of the electrolyte is 5% to 15%.

25. The battery cell of any one of claims 18-24, wherein, The electrolyte includes dimethyl carbonate and linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 2.0 to 7.

0.

26. The battery cell of claim 25, wherein, The mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.

0.

27. The battery cell of any one of claims 18-26, wherein, The electrolyte includes lithium salt, and the mass percentage of the lithium salt in the total mass of the electrolyte is 13% to 20%.

28. The battery cell of claim 27, wherein, The lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and fluorine-containing sulfonimide salt, and the fluorine-containing sulfonimide salt includes one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis-trifluoromethylsulfonylimide LiTFSI.

29. The battery cell of claim 27, wherein, The lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonylimide LiFSI.

30. The battery cell of claim 29, wherein, In the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfonylimide LiFSI is 1.2:1 to 2:

1.

31. The battery cell of any one of claims 18-30, wherein, The electrolyte further includes an additive, and the additive includes carbonate-based additives.

32. The battery cell of claim 31, wherein, The mass percentage of the carbonate-based additives in the electrolyte is 0.5% to 7% based on the total mass of the electrolyte.

33. The battery cell of claim 31 or 32, wherein, The carbonate-based additives include vinylene carbonate VC and fluoroethylene carbonate FEC.

34. The battery cell of either claim 31 or 32, wherein, The additive includes vinylene carbonate VC, and the mass percentage of the vinylene carbonate VC in the electrolyte is 0.5% to 2% based on the total mass of the electrolyte.

35. The battery cell of either claim 31 or 32, wherein, The additive includes fluoroethylene carbonate FEC, and the mass percentage of the fluoroethylene carbonate FEC in the electrolyte is 0.1% to 1% based on the total mass of the electrolyte.

36. The battery cell of any one of claims 1-35, wherein, The lithium-containing phosphate composition has a general formula as shown in Formula I, Li x A y Me a M b P 1-c X c Y z Formula I, 0.1≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or more of Na, K and Mg; Me includes one or more of Mn, Fe, Co and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X includes one or more of S, Si, Cl, B, C and N; and Y includes one or more of O and F. M includes one or more of Al, Ti, V and Mg.

37. The battery cell of claim 36, wherein, The positive electrode active material satisfies at least one of the following conditions:

38. The battery cell of claim 36 or 37, wherein, (1) the positive electrode active material contains Al element, and the mass content is 0.01 to 0.05% based on the total mass of the positive electrode active material; (2) the positive electrode active material contains Ti element, and the mass content is 0.01 to 0.03% based on the total mass of the positive electrode active material; ​ (3) the positive electrode active material contains V element, the mass content is 0.1-0.3%, based on the total mass of the positive electrode active material; (4) the positive electrode active material contains Mg element, the mass content is 0.001-0.01%, based on the total mass of the positive electrode active material.

39. The battery cell of any one of claims 1-38, wherein, In a cross section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate includes first lithium-containing phosphate particles having a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles having a longest diameter of 1 μm to 3 μm.

40. The battery cell of claim 39, wherein, In a cross section of the positive electrode film layer along the thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

41. The battery cell of any one of claims 1-40, wherein: a distance between center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, the center lines being parallel to the first direction; and / or a distance between center lines of two adjacent negative electrode tabs is 10 mm to 350 mm, the center lines being parallel to the first direction.

42. The battery cell of claim 41, wherein: a distance between center lines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or a distance between center lines of two adjacent negative electrode tabs is 20 mm to 330 mm.

43. The battery cell of claim 41, wherein, The battery cell further includes a top cover including a positive electrode terminal and a negative electrode terminal having opposite polarities, the positive electrode terminal and the negative electrode terminal being respectively configured to be electrically connected with the positive electrode tab and the negative electrode tab.

44. The battery cell of any one of claims 1-43, wherein, The battery has a square-shaped housing, the housing having a thickness of 30 mm to 55 mm, a width of 150 mm to 250 mm, and a height of 90 mm to 120 mm.

45. The battery cell of any one of claims 1-44, wherein, The battery cell is configured to have a charging time of 10-17 min from 10% SOC to 80% SOC at room temperature.

46. A battery device, comprising: The battery device includes the battery cell of any one of claims 1-45, the battery device being at least one of a battery module, a battery pack, and an energy storage device.

47. An electrical device, comprising: The battery cell or the battery device of any one of claims 1-46.

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