Battery monomer, battery device and electric device

Abstract

The invention provides a battery monomer, a battery device and a power utilization device. In the battery monomer provided by the invention, the surface density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm < 2 > to 0.4 g / 1540.25 mm < 2 >; the surface density of the single-sided negative electrode film layer is 0.15 g / 1540.25 mm < 2 > to 0.19 g / 1540.25 mm < 2 >; in the first direction, the size of the positive electrode film layer is W1 mm, the size of the negative electrode film layer is W2 mm, W2 is larger than W1, and the difference value between W2 and W1 ranges from 3 mm to 5 mm.

Description

[0001] Cross - Reference to Related Applications This application claims the priority of PCT patent application PCT / CN2024 / 116576 titled "Battery Cell, Battery Device and Electrical Device" filed on September 3, 2024, and the entire content of this application is incorporated herein by reference. Technical Field

[0002] This application relates to the technical field of batteries, and in particular, to a battery cell, a battery device and an electrical device. Background Art

[0003] In recent years, batteries have been widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the popularization of battery applications, higher requirements have also been put forward for their energy density, fast charging performance, cycling performance, service life, safety performance, etc. Summary of the Invention

[0004] The purpose of this application is to provide a new type of battery cell, which has excellent energy density, fast charging performance, cycling performance, and can also have a relatively low DC internal resistance.

[0005] To achieve the above object, a first aspect of this application provides a battery cell, including a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The negative electrode plate includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. Wherein, the positive electrode film layer includes a positive active material, and the positive active material includes a lithium-containing phosphate. The areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 ; the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 ; the positive current collector includes a positive current collecting portion and at least two positive electrode tabs disposed on the same side of the positive current collecting portion, and the positive electrode tabs extend from the positive current collecting portion along a first direction; the negative current collector includes a negative current collecting portion and at least two negative electrode tabs disposed on the same side of the negative current collecting portion, and the negative electrode tabs extend from the negative current collecting portion along the first direction; along the first direction, the size of the positive electrode film layer is W 1 mm, the size of the negative electrode film layer is W 2 mm, where W 2 > W 1 and W 2The difference from W 1 is 3 mm to 5 mm.

[0006] The formation of lithium dendrites is closely related to the capacity design of the positive and negative electrode sheets. In this application, by reasonably controlling the film areal density of the positive and negative electrode sheets within a reasonable range, the current density in the positive and negative electrode films becomes more uniform, effectively solving the problem of large-area lithium deposition on the negative electrode sheet; furthermore, as the charging rate of the battery cell increases, since the root position of the tab is an electron aggregation area, the negative electrode film near the root of the tab is more likely to generate lithium dendrites. On the basis of reasonably controlling the areal density of the positive and negative electrode films, by further reasonably controlling the size W 2 of the negative electrode film and the size W 1 of the positive electrode film have the above difference, which can further improve the lithium deposition problem near the root of the tab on the negative electrode sheet, so that the battery has excellent fast charging performance and cycle performance.

[0007] In any embodiment, the areal density of the single-sided positive electrode film is 0.335 g / 1540.25 mm 2 to 0.38 g / 1540.25 mm 2 , and the areal density of the single-sided negative electrode film is 0.15 g / 1540.25 mm 2 to 0.165 g / 1540.25 mm 2 .

[0008] In the battery cell provided by this application, when the coating areal density of the positive and negative electrode films is within the above range, it can further balance and improve the energy density and fast charging performance of the battery.

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

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

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

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

[0013] In any embodiment, the tap density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm3 。

[0014] When the compaction density of the negative electrode sheet is within 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 includes 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 includes 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 by the present application, when the graphite as the negative electrode active material has a particle size within 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% - 95%.

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

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

[0021] In any embodiment, 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 first artificial graphite, and the negative electrode active material in the second negative electrode active material layer includes second artificial graphite. 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 by the present application, when the above double-layer coating scheme is adopted 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 to 6 μm.

[0027] In any embodiment, the ratio of the single-sided 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-sided 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-sided 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 fast charging performance of the battery can be further balanced.

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

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

[0032] In any embodiment, the organic solvent includes a linear carboxylic acid ester, and the mass ratio 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 the general structural formula of R 1 -COO-R 2 wherein R 1 and R 2 each independently includes one or more of an alkyl group of C 1 ~C 5 and a haloalkyl group of C 1 ~C 5

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

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

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

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

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

[0039] When the above types and mass percentages of carbonates are used as organic solvents in the electrolyte, side reactions and gas generation during battery cycling can be improved, so that the battery can simultaneously have good cycling performance.

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

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

[0042] When dimethyl carbonate and a linear carboxylic acid ester with the above mass ratio are simultaneously used as organic solvents in the electrolyte, by combining the two solvents, the fast charging performance and cycling performance of the battery can be further improved.

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

[0044] In any embodiment, the lithium salt includes at least two of lithium hexafluorophosphate LiPF 6 and fluorosulfonimide salts, and the fluorosulfonimide salts include one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0045] Lithium hexafluorophosphate is not prone to gas generation during cycling, which can further improve the cycling performance of the battery; while the fluorosulfonimide salt has strong dissociation ability, which can further improve the fast charging performance of the battery.

[0046] In any embodiment, the lithium salt includes lithium hexafluorophosphate LiPF 6 and lithium bis(fluorosulfonyl)imide LiFSI.

[0047] In any embodiment, in the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF 6 to lithium bis(fluorosulfonyl)imide LiFSI is 1.2:1 to 2:1.

[0048] When lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide within the above mass ratio range are simultaneously used in the electrolyte, the fast charging performance and cycling performance of the battery can be further balanced.

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

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

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

[0052] In the battery cell provided by this application, a carbonate additive within the above range by mass, such as fluoroethylene carbonate and vinylene carbonate, is further added to the electrolyte. It can form a SEI film on the surface of the negative electrode, thereby reducing the side reactions occurring between the electrode sheet and the electrolyte, and further enabling the battery to have good cycling performance.

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

[0054] When vinylene carbonate within the above mass proportion range is added as an additive to the electrolyte, the formed SEI film is relatively stable, which is beneficial to further improving the cycling performance of the battery.

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

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

[0057] In any embodiment, the general formula of the lithium-containing phosphate is shown in Formula I, Li x A y Me a M b P 1-c X c Y z Formula I, 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, 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, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

[0058] When the lithium-containing phosphate as the positive electrode active material has the above chemical general formula, the energy density of the battery can be further improved.

[0059] In any embodiment, M includes one or more of Al, Ti, V, and Mg.

[0060] In any embodiment, the positive electrode active material satisfies at least one of the following: (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, and the mass content is 0.1% to 0.3% based on the total mass of the positive electrode active material; (4) The positive electrode active material contains Mg element, and the mass content is 0.001% to 0.01% based on the total mass of the positive electrode active material.

[0061] When the lithium-containing phosphate as the positive electrode active material contains elements such as Al, Ti, and V, its specific capacity can be further improved.

[0062] In any embodiment, in the cross-section of the positive electrode film layer in the thickness direction, the lithium-containing phosphate includes 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.

[0063] In the battery cell provided by the present application, when the positive electrode active material contains lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm, it can further improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery and making the battery have excellent safety performance.

[0064] In the battery cell provided by the present application, when the lithium-containing phosphate serving as the positive electrode active material contains both 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, the tap density of the electrode sheet is improved by the grading of large and small particles, thereby further enhancing the energy density of the battery.

[0065] 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.

[0066] In the lithium-containing phosphate serving as the positive electrode active material, when the number of the first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm is greater than the number of the second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, the DC internal resistance and fast charging performance of the battery can be further balanced.

[0067] In any embodiment, the distance between the centerlines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the centerlines are parallel to the first direction; and / or, The distance between the centerlines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the centerlines are parallel to the first direction.

[0068] In any embodiment, the distance between the centerlines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or, The distance between the centerlines of two adjacent negative electrode tabs is 20 mm to 330 mm.

[0069] In the battery cell provided by the present application, when the positive and negative current collectors include at least two tabs having the above structural features, it can further improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery and making the battery have better safety performance.

[0070] In any embodiment, the battery cell further includes a top cover, the top cover includes a positive electrode terminal and a negative electrode terminal with opposite polarities, and the positive electrode terminal and the negative electrode terminal are respectively used for electrically connecting with the positive electrode tab and the negative electrode tab.

[0071] In a conventional battery, a jumper is required to connect the electrode terminal and the tab, but this will reduce the utilization rate of the electrode assembly and the energy density of the battery. When the above structure is adopted in the battery cell provided by the present application, the setting of the jumper can be cancelled to effectively solve this problem, reduce the internal resistance of the battery, and further balance the improvement of the battery energy density and the fast charging performance.

[0072] In any embodiment, the housing of the battery is square, and the thickness of the housing is 30 mm to 55 mm, the width is 150 mm to 250 mm, and the height is 90 mm to 120 mm.

[0073] In any embodiment, the battery cell is configured to have a charging time of 10 to 17 minutes for charging from 10% SOC to 80% SOC at room temperature.

[0074] The battery cell provided by the present application has excellent fast charging performance.

[0075] The second aspect of the present application further provides a battery device, including the battery cell of the first aspect of the present application, and the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0076] The third aspect of the present application further provides an electrical device, including the battery cell of the first aspect of the present application or the battery device of the second aspect of the present application. Description of the Drawings

[0077] Figure 1 is a schematic diagram of the size of the electrode sheet film layer in an embodiment of the present application; Figure 2 is an electron microscope observation result diagram of the longitudinal section of the positive electrode sheet in an embodiment of the present application; Figure 3 is a schematic diagram of the electrode sheet in an embodiment of the present application; Figure 4 is an exploded view of the battery cell in an embodiment of the present application; Figure 5 is one of the schematic diagrams of the battery cell in an embodiment of the present application; Figure 6 is another schematic diagram of the battery cell in an embodiment of the present application; Figure 7 is yet another schematic diagram of the battery cell in an embodiment of the present application; Figure 8 is a schematic diagram of the battery cell in an embodiment of the present application; Figure 9 is Figure 8 the exploded view of the battery cell shown in an embodiment of the present application; Figure 10 is a schematic diagram of the battery module in an embodiment of the present application; Figure 11 is a schematic diagram of the battery pack in an embodiment of the present application; Figure 12 is Figure 11 the exploded view of the battery pack shown in an embodiment of the present application; Figure 13Schematic diagram of an electrical device using a battery cell as a power source according to an embodiment of the present application.

[0078] Explanation of reference numerals: 1 Battery pack; 2 Upper box body; 3 Lower box body; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly; 10 Battery cell; 11 Current collector; 11a Current collecting part; 111a Positive current collecting part; 112a Negative current collecting part; 11b Tab; 111b Positive tab; 112b Negative tab; F1 First direction; W 1 Dimension of the positive electrode film layer in the first direction; W 2 Dimension of the negative electrode film layer in the first direction; L Center line; 13 Top cover; 131 Electrode terminal; 14 Housing. Specific embodiments

[0079] Hereinafter, embodiments of the battery cell and the electrical device of the present application specifically disclosed will be described in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid the following descriptions from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0080] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, 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, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0081] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0082] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0083] Unless otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out in sequence, or may also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may also include steps (c), (a) and (b), etc.

[0084] Unless otherwise specified, the terms "comprising" and "including" mentioned in the present application mean open-ended or may also be closed-ended. For example, the "comprising" and "including" may mean that other components not listed may also be included or comprised, or may only include or comprise the listed components.

[0085] Unless otherwise specified, in the present application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0086] As the charging rate of the battery cell increases, lithium ions will be released from the positive electrode active material faster, and the concentration distribution of lithium ions in the electrolyte phase may be uneven. As a result, lithium ions are likely to accumulate on the surface of the local negative electrode active material and cannot be embedded in the negative electrode active material equally. Thus, they gain electrons on the surface of the negative electrode active material to form silver-white metallic lithium, namely "lithium dendrites". The formation of lithium dendrites will not only reduce the battery performance, such as shortening the cycle life and poor fast charging performance, etc. At the same time, the continuously deposited metallic lithium will also fall off from the surface of the negative electrode active material, thus forming "dead lithium" that cannot continue to participate in the reaction, resulting in a decrease in the energy density of the secondary battery.

[0087] To solve the above problems, the present application provides a battery cell, comprising a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The negative electrode plate includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. Wherein, the positive electrode film layer includes a positive active material, and the positive active material includes a lithium-containing phosphate. The areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 ; the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 ; the positive current collector includes a positive current collecting portion and at least two positive electrode tabs disposed on the same side of the positive current collecting portion. The positive electrode tabs extend from the positive current collecting portion along a first direction; the negative current collector includes a negative current collecting portion and at least two negative electrode tabs disposed on the same side of the negative current collecting portion. The negative electrode tabs extend from the negative current collecting portion along the first direction; along the first direction, the size of the positive electrode film layer is W 1 mm, and the size of the negative electrode film layer is W 2 mm, where W 2 > W 1 , and the difference between W 2 and W 1 is 3 mm to 5 mm.

[0088] As used herein, the "areal density" of the positive electrode film layer or the negative electrode film layer has the meaning well known in the art and can be tested by methods known in the art. For example, take a single-sided coated and cold-pressed negative electrode plate (if it is a double-sided coated negative electrode plate, one side of the negative electrode film layer can be wiped off first), punch it into small round pieces with an area of S1, weigh it, and record it as M1. Then wipe off the negative electrode film layer of the above weighed negative electrode plate and weigh the weight of the negative current collector, record it as M0. The areal density of the negative electrode film layer = (the weight M1 of the negative electrode plate - the weight M0 of the negative current collector) / S1. To ensure the accuracy of the test results, multiple groups (such as 10 groups) of samples to be tested can be tested, and the average value can be calculated as the test result.

[0089] In some embodiments, the positive electrode plate, the negative electrode plate and the separator can be made into an electrode assembly by a winding process or a stacking process.

[0090] In some embodiments, the battery cell is a wound battery, combined with Figure 1As shown, after the electrode sheet is unwound from the wound state, the positive current collector includes a positive current collecting portion 111a and at least two positive electrode tabs 111b disposed on the same side of the positive current collecting portion 111a. The positive electrode tabs 111b extend from the positive current collecting portion 111a along the first direction F1. The negative current collector includes a negative current collecting portion 112a and at least two negative electrode tabs 112b disposed on the same side of the negative current collecting portion 112a. The negative electrode tabs 112b extend from the negative current collecting portion 112a along the first direction F1. Wherein, the size W of the negative electrode film layer in the first direction 2 > the size W of the positive electrode film layer in the first direction 1 , and the difference is 3 mm to 5 mm.

[0091] The formation of lithium dendrites is closely related to the capacity design of the positive and negative electrode sheets. In this application, 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 film layers is made more uniform, effectively solving the problem of large-area lithium deposition on the negative electrode sheet; furthermore, as the charging rate of the battery cell increases, since the root position of the electrode tab is an electron aggregation area, the negative electrode film layer near the root of the electrode tab is more likely to generate lithium dendrites. On the basis of reasonably controlling the areal density of the positive and negative electrode film layers, by further reasonably controlling the size W 2 of the negative electrode film layer and the size W 1 of the positive electrode film layer have the above difference, which can further improve the problem of lithium deposition near the root of the electrode tab on the negative electrode sheet, thereby enabling the battery to have excellent fast charging performance and cycling performance.

[0092] [Negative electrode sheet] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. As an example, the negative current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative current collector.

[0093] In some embodiments, the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2 , such as 0.15 g / 1540.25mm 2 , 0.16 g / 1540.25mm 2 , 0.17 g / 1540.25mm 2 , 0.18 g / 1540.25mm 2 , 0.19 g / 1540.25mm 2 etc., or 0.15 g / 1540.25mm 2To 0.19 g / 1540.25mm 2 Other unlisted values within the range.

[0094] In some embodiments, the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25mm 2 To 0.165 g / 1540.25mm 2 .

[0095] In the battery cell provided by the present application, when the coating areal density of the negative electrode film layer is within the above range, the energy density of the battery can be improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby taking into account the improvement of the fast charging performance of the battery.

[0096] In some embodiments, the negative electrode film layer includes a negative electrode active material.

[0097] In some embodiments, the average particle size Dv50 of the negative electrode active material is 8 μm to 15 μm, such as 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc., or other unlisted values within the range of 8 μm to 15 μm. In some embodiments, the negative electrode active material includes graphite.

[0098] As used herein, "average particle size Dv50" means: in the particle size distribution of the particles, starting from the small particle size side, the particle size corresponding to the cumulative volume distribution percentage reaching 50%. The measurement method can refer to GB / T19077-2016 / ISO13320:2009 and be measured using a Malvern 2000 (MasterSizer 2000) laser particle size analyzer.

[0099] In the battery cell provided by the present application, when the negative electrode active material (such as graphite) has a particle size within the above range, it has a large specific surface area, the migration channels between the graphite layers for lithium ions increase and the migration path becomes shorter, thereby accelerating the insertion and extraction speed of lithium ions between the graphite layers, making the battery cell have good fast charging performance; at the same time, when the negative electrode active material (such as graphite) has a particle size within the above range, it can also improve the DC internal resistance of the battery cell, thereby reducing the heat generation of the battery and making the battery have good safety performance.

[0100] In some embodiments, the average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm, such as 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, etc., or other unlisted values within the range of 9.5 μm to 11.5 μm.

[0101] When the negative electrode active material (such as graphite) has a particle size within the above range, the fast charging performance and DC internal resistance of the battery can be further improved, and at the same time, the battery can have good cycle performance.

[0102] In some embodiments, the graphitization degree of the negative electrode active material is 90% - 95%.

[0103] In some embodiments, the graphitization degree of the negative electrode active material is 92% - 95%.

[0104] When the graphitization degree of the negative electrode active material is within the above range, the capacity can be further improved.

[0105] As used herein, "graphitization degree" refers to an index that measures the degree to which carbon atoms form a close-packed hexagonal graphite crystal structure. It can be tested using an X-ray diffractometer (such as Bruker D8 Discover), referring to JIS K0131 - 1996 and JB / T 4220 - 2011, to obtain the average layer spacing d of the (002) crystal plane in the crystal structure of the carbon material. 002 and then the graphitization degree is calculated according to the formula g = (0.344 - d 002 ) / (0.344 - 0.3354) × 100%. In the above formula, d 002 is the average layer spacing of the (002) crystal plane in the crystal structure of the carbon material expressed in nanometers (nm).

[0106] In some embodiments, the negative electrode film layer includes at least two 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 first artificial graphite, and the negative electrode active material in the second negative electrode active material layer includes second artificial graphite. The average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

[0107] 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, etc., or other unlisted values within the range of 11 μm to 15 μm.

[0108] 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, etc., or other unlisted values within the range of 8 μm to 15 μm.

[0109] In some embodiments, the average particle size Dv50 of the second artificial graphite is from 9.5 μm to 11.5 μm, such as 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, etc., or other unlisted values within the range of 9.5 μm to 11.5 μm.

[0110] In the battery cell provided by the present application, when the above double-layer coating scheme is adopted in the negative electrode film layer, the kinetic performance of the battery can be further improved.

[0111] In some embodiments, the negative electrode film layer may further optionally include a binder. The binder may 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).

[0112] In some embodiments, the negative electrode film layer may further optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0113] In some embodiments, the negative electrode film layer may further optionally include other additives, such as a thickener (such as sodium carboxymethyl cellulose (CMC-Na)).

[0114] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0115] In some embodiments, the thickness of the negative electrode current collector is from 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.

[0116] In some embodiments, the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector is from 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.

[0117] In some embodiments, the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 13 to 20.

[0118] In some embodiments, the single-sided thickness of the negative electrode film layer corresponds to the single-sided thickness of the negative electrode film layer of the battery cell corresponding to the 0% SOC state. The battery cell in the 0% SOC state means: the battery cell is discharged at 1 / 3C to 2.0V and then discharged at 0.05C to 2.0V. In the battery cell provided in the present application, when the ratio of the single-sided 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 fast charging performance of the battery can be further balanced.

[0119] In some embodiments, in combination Figure 3 As shown, the current collector 11 includes a current collecting portion 11a and at least two tabs 11b provided on the same side of the current collecting portion 11a. The tabs 11b extend from the current collecting portion 11a along the first direction F1. Among them, the distance between the center lines L of two adjacent tabs 11b is 10 mm to 350 mm. The center line L is 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, etc., or other values not listed within the range of 10 mm to 350 mm.

[0120] In some embodiments, the distance between the center lines L of two adjacent tabs 11b is 20 mm to 330 mm. The center line L is 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, etc., or other values not listed within the range of 20 mm to 330 mm.

[0121] In some embodiments, in combination Figure 3 and Figure 4 As shown, the current collector 11 may be a positive electrode current collector, and the tab 11b may be a positive electrode tab 111b.

[0122] In some embodiments, in combination Figure 3 and Figure 4 As shown, the current collector 11 may be a negative electrode current collector, and the tab 11b may be a negative electrode tab 112b.

[0123] In some embodiments, the negative electrode current collector includes a negative electrode current collecting portion and at least two negative electrode tabs disposed on the same side of the negative electrode current collecting portion, and the negative electrode tabs extend from the negative electrode current collecting portion along a first direction. In some embodiments, the distance between the centerlines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the centerlines are parallel to the first direction, such as 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, etc., or other unlisted values within the range of 10 mm to 350 mm.

[0124] In some embodiments, the distance between the centerlines of two adjacent negative electrode tabs is 20 mm to 330 mm, and the centerlines are parallel to the first direction, such as 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, etc., or other unlisted values within the range of 20 mm to 330 mm.

[0125] In some embodiments, in combination Figure 3 As shown, the centerline L refers to the symmetry axis passing through the midpoint of the tab 11b along the length direction of the current collector 11, and the centerline L is parallel to the first direction F1. In some embodiments, the dimensions of each tab 11b along the length direction of the current collector 11 are equal.

[0126] In some embodiments, in combination Figure 3 As shown, the distance between the centerlines L of two adjacent tabs 11b includes S1 or S2, where S1 and S2 may be equal (in this case, the adjacent tabs are equally spaced), and S1 and S2 may also be unequal (in this case, the adjacent tabs are unequally spaced).

[0127] In the battery cell provided by the present application, when the positive and negative electrode current collectors include at least two tabs having the above structural features, it can further improve the overcurrent capacity, improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery, and making the battery have better safety performance.

[0128] In some embodiments, the negative electrode plate can be prepared in the following manner: dispersing the above components for preparing the negative electrode plate, 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 processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0129] In some embodiments, the compaction density of the negative electrode tab is 1.3 g / cm 3 to 1.6 g / cm 3 , such as 1.3 g / cm 3 , 1.4 g / cm 3 , 1.5 g / cm 3 , 1.6 g / cm 3 , etc., or other unlisted values within the range of 1.3 g / cm 3 to 1.6 g / cm 3 .

[0130] In some embodiments, the compaction density of the negative electrode tab is 1.35 g / cm 3 to 1.55 g / cm 3 , such as 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 , etc., or other unlisted values within the range of 1.35 g / cm 3 to 1.55 g / cm 3 .

[0131] In some embodiments, the compaction density of the negative electrode tab corresponds to that of the negative electrode film layer of the battery cell in the 0% SOC state. The battery cell in the 0% SOC state means: the battery cell is discharged to 2.0 V at 1 / 3 C and then discharged to 2.0 V at 0.05 C. When used herein, the "compaction density" of the electrode tab is: compaction density = areal density / (electrode tab thickness - current collector thickness), and its measurement method can refer to GB / T24533-2009.

[0132] 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.

[0133] [Positive electrode tab] In some embodiments, the positive electrode tab includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. As an example, the positive current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive current collector.

[0134] In some embodiments, the areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2, such as 0.33 g / 1540.25mm 2 , 0.34 g / 1540.25mm 2 , 0.35 g / 1540.25mm 2 , 0.36 g / 1540.25mm 2 , 0.37 g / 1540.25mm 2 , 0.38 g / 1540.25mm 2 , 0.39 g / 1540.25mm 2 , 0.4 g / 1540.25mm 2 etc., or other unlisted values within the range from 0.33g / 1540.25mm 2 to 0.4 g / 1540.25mm 2

[0135] In some embodiments, the areal density of the single-sided positive electrode film layer is 0.335 g / 1540.25mm 2 to 0.38g / 1540.25mm 2 .

[0136] In the battery cell provided by the present application, when the coating areal density of the positive electrode film layer is within the above range, the energy density of the battery can be improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby taking into account the improvement of the fast charging performance of the battery.

[0137] In some embodiments, the positive electrode film layer includes a positive electrode active material.

[0138] In some embodiments, the positive electrode active material includes a lithium-containing phosphate with an olivine structure.

[0139] In some embodiments, the general formula of the composition of the lithium-containing phosphate with an olivine structure is as shown in Formula I, Li x A y Me a M b P 1-c X c Y z Formula I, ​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, 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, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

[0140] As used herein, "the general formula of the lithium-containing phosphate having an olivine structure is shown in Formula I" is not limited to the substances represented by the general formula, but also includes other substances formed by further appropriate modification on the basis of the general formula, which are not limited herein. The use of the "general formula" is only for convenience of description and does not intend to limit the present application. It can be understood that new materials or substances obtained by appropriate modification on the basis of the listed cathode active materials are also within the scope of the cathode active materials. The aforementioned appropriate modification refers to the acceptable modification methods for the cathode active materials, and non-limiting examples include coating modification.

[0141] When the lithium-containing phosphate as the cathode active material has the above chemical general formula, the energy density of the battery can be further improved.

[0142] In some embodiments, M includes one or more of Al, Ti, V, and Mg.

[0143] In some embodiments, the cathode active material contains Al element, and its mass content is 0.001% - 0.05%, optionally 0.01% - 0.05%, based on the total mass of the cathode active material. For example, 0.001%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, etc., or other unlisted values within the range of 0.001% - 0.05%, based on the total mass of the cathode active material.

[0144] In some embodiments, the cathode active material contains Ti element, and its mass content is 0.001% - 0.03%, optionally 0.01 - 0.03%, based on the total mass of the cathode active material. For example, 0.001%, 0.01%, 0.02%, 0.03%, etc., or other unlisted values within the range of 0.001% - 0.03%, based on the total mass of the cathode active material.

[0145] In some embodiments, the positive electrode active material contains V element, and its mass content is 0.001% to 0.3%, optionally 0.1 to 0.3%, based on the total mass of the positive electrode active material. For example, 0.001%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, etc., or other unlisted values within the range of 0.001% to 0.3%, based on the total mass of the positive electrode active material.

[0146] In some embodiments, the positive electrode active material contains Mg element, and the mass content is 0.001% to 0.01%, based on the total mass of the positive electrode active material. Optionally, it 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.

[0147] When the lithium-containing phosphate as the positive electrode active material contains elements such as Al, Ti, V, and Mg, it can further improve the structural stability of the material and enhance the cycling performance.

[0148] In some embodiments, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate with olivine structure includes a first lithium-containing phosphate particle with a longest diameter of 0.05 μm to 0.3 μm and a second lithium-containing phosphate particle with a longest diameter of 1 μm to 3 μm.

[0149] In some embodiments, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate with olivine structure includes a first lithium-containing phosphate particle with a longest diameter of 0.05 μm to 0.3 μm. For example, 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, etc., or other unlisted values within the range of 0.05 μm to 0.3 μm.

[0150] In some embodiments, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate with olivine structure includes a second lithium-containing phosphate particle with a longest diameter of 1 μm to 3 μm. For example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, etc., or other unlisted values within the range of 1 μm to 3 μm.

[0151] In some embodiments, since the first lithium-containing phosphate and the second lithium-containing phosphate have been fully mixed during the preparation of the slurry and uniformly coated on the current collector to form the positive electrode film layer, therefore, any cross-section taken along the thickness direction of the electrode can represent the particle size and distribution of the lithium-containing phosphate in the entire electrode; when selecting the cross-section, it is preferred to select a relatively flat cross-section in the middle of the electrode to more clearly observe the distribution of the lithium-containing phosphate therein.

[0152] In some embodiments, the "longest diameter" means: 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; determining the longest diameter of the lithium-containing phosphate particles by performing a scanning electron microscope (SEM) test on the longitudinal section of the positive electrode film layer. Specifically, among the distances between any two points on the outer peripheral edge line of the lithium-containing phosphate particles, the maximum value is the "longest diameter" of the particles. In some embodiments, as Figure 2 shown in the longitudinal section of the electrode sheet along the thickness direction, which shows the longest diameter of a single particle that satisfies the first lithium-containing phosphate particle (with a longest diameter of 0.05 μm to 0.3 μm), and also shows the shortest diameter of a single particle that satisfies the second lithium-containing phosphate particle (with a longest diameter of 1 μm to 3 μm).

[0153] In the battery cell provided by the present application, when the positive electrode active material contains lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm, it can further improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery, and enabling the battery to have excellent safety performance.

[0154] In the battery cell provided by the present application, when the lithium-containing phosphate as the positive electrode active material contains both the first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and the second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, the tap density of the electrode sheet can be effectively improved by the method of grading of large and small particles, so that the battery cell also has a relatively high energy density.

[0155] 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.

[0156] In the lithium-containing phosphate as the positive electrode active material, when the number of the first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm is greater than the number of the second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, the improvement of the DC internal resistance and the fast charging performance of the battery can be further taken into account.

[0157] It should be noted that the first lithium-containing phosphate particle material with a relatively small size and a longest diameter of 0.05 μm to 0.3 μm is one of the positive electrode active materials of the battery cell of the present application, and the particle size range of 0.05 μm to 0.3 μm is a characteristic parameter of the material itself.

[0158] The second lithium-containing phosphate particle material with a relatively large size and a longest diameter of 1 μm to 3 μm is one of the positive electrode active materials of the battery cell of the present application, and the particle size range of 1 μm to 3 μm is a characteristic parameter of the material itself.

[0159] Those skilled in the art can mix the lithium-containing phosphate particulate materials within the above two size ranges according to actual needs.

[0160] In some embodiments, the positive electrode film layer may optionally further include a positive electrode conductive agent. The present application does not particularly limit the type of the positive electrode conductive agent. By way of example, the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0161] In some embodiments, the positive electrode film layer may optionally further include a positive electrode binder. The present application does not particularly limit the type of the positive electrode binder. By way of example, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0162] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. By way of example of the metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. By way of example, the metal material may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. By way of example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0163] In some embodiments, the thickness of the positive electrode current collector is 10 μm to 15 μm, such as 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc., or other unlisted values within the range of 10 μm to 15 μm.

[0164] In some embodiments, the ratio of the single-sided thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 5 to 12, such as 5, 6, 7, 8, 9, 10, 11, 12, etc., or other unlisted values within the range of 5 to 12.

[0165] In some embodiments, the ratio of the single-sided thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 6 to 10.

[0166] In the battery cell provided by the present application, when the ratio of the single-sided 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, which will not cause energy density loss due to excessive thickness, nor will it cause problems such as poor over-current capacity and low tensile strength resulting in pole piece cracking due to excessive thinness, and further takes into account improving the energy density and fast charging performance of the battery.

[0167] In some embodiments, the positive electrode current collector includes a positive electrode current collecting portion and at least two positive electrode tabs disposed on the same side of the positive electrode current collecting portion. The positive electrode tabs extend from the positive electrode current collecting portion in a first direction. Among them, the distance between the center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the center line is 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, etc., or other unlisted values within the range of 10 mm to 350 mm.

[0168] In some embodiments, the distance between the center lines of two adjacent positive electrode tabs is 20 mm to 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, etc., or other unlisted values within the range of 20 mm to 330 mm.

[0169] In the battery cell provided by the present application, when the positive and negative current collectors include at least two tabs having the above structural features, it can further improve the over-current capacity, improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery and making the battery have better safety performance.

[0170] In some embodiments, the size of the positive electrode film layer in the first direction is W 1 mm, and the size of the negative electrode film layer in the first direction is W 2 mm, where W 2 > W 1 , and the difference between W 2 and W 1 is 3 mm to 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, etc., or other unlisted values within the range of 3 mm to 5 mm.

[0171] During the cycling process of the battery, lithium ions that cannot be embedded in the negative electrode in time may form lithium dendrites on the surface of the negative electrode, deteriorating the cycling performance of the battery. In the battery cell provided by this application, when the size W of the negative electrode film layer 2 and the size W of the positive electrode film layer 1 have the above relationship, it can improve the formation of lithium dendrites on the surface of the negative electrode, so that the battery can simultaneously have better cycling performance.

[0172] In some embodiments, the positive electrode plate can be prepared in the following manner: Disperse the components for preparing the positive electrode plate, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coat the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0173] In some embodiments, the tap density of the positive electrode plate is 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 , etc., or other unlisted values within the range of 2.3 g / cm 3 to 2.6 g / cm 3 .

[0174] In some embodiments, the tap density of the positive electrode plate is 2.4 g / cm 3 to 2.55 g / cm 3 .

[0175] When the tap density of the positive electrode plate is within the above range, it can further improve the energy density of the battery while ensuring the kinetic performance.

[0176] In some embodiments, the tap density of the positive electrode plate corresponds to the tap density of the positive electrode film layer of the battery cell in the 0% SOC state. The battery cell in the 0% SOC state refers to the state in which the battery cell is discharged to 2.0 V at 1 / 3 C and then discharged to 2.0 V at 0.05 C.

[0177] [Electrolyte] The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. For example, the electrolyte can be liquid, solid, or gel state.

[0178] In some embodiments, the electrolyte is an electrolytic solution. The electrolytic solution includes an electrolyte salt and an organic solvent.

[0179] In the embodiments of the present application, the types and contents of the organic components in the electrolytic solution have meanings well-known in the art and can be detected by equipment and methods well-known in the art. For example, the composition of the electrolytic solution can be measured by liquid chromatography, gas chromatography, ion chromatography, liquid nuclear magnetic resonance, etc. Exemplarily, qualitative and quantitative analysis of the organic components in the electrolytic solution can be performed by gas chromatography with reference to GB / T9722-2006 General Rules for Gas Chromatography of Chemical Reagents.

[0180] The test sample in the embodiments of the present application can be a newly prepared electrolytic solution as the sample, or the free electrolytic solution obtained from the battery after the battery is fully discharged (discharged to the lower cut-off voltage so that the charged state of the battery is about 0% SOC) as the sample.

[0181] In the embodiments of the present application, the types and contents of the inorganic components / lithium salt concentration in the electrolytic solution have meanings well-known in the art and can be detected by equipment and methods well-known in the art. For example, qualitative or quantitative analysis of the inorganic components / lithium salt concentration in the electrolytic solution can be performed by ion chromatography with reference to the standard JY / T020-1996 General Rules for Ion Chromatographic Analysis. In the embodiments of the present application, a newly prepared electrolytic solution can be taken as the sample, or the free electrolytic solution obtained from the battery after the battery is fully discharged (discharged to the lower cut-off voltage so that the charged state of the battery is about 0% SOC) as the sample, and detected by ion chromatography analysis method.

[0182] In some embodiments, the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

[0183] In the battery cell provided by the present application, when the above types of organic solvents are used in the electrolytic solution, the kinetic performance of the battery can be further improved.

[0184] In some embodiments, the organic solvent includes a linear carboxylic acid ester. Based on the total mass of the electrolytic solution, the mass ratio of the linear carboxylic acid ester is 40% to 75%, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, etc., or other unlisted values within the range of 40% to 75%.

[0185] In some embodiments, the linear carboxylic acid ester has the structural general formula of R 1 -COO-R 2 where R 1 and R 2 each independently includes an alkyl group of C 1 ~C 5 and C1 ~C 5 one or more of the haloalkyl groups thereof.

[0186] In some embodiments, the linear carboxylic acid esters include one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

[0187] When the above types and mass ratios of linear carboxylic acid esters are used as organic solvents in the electrolyte, due to the low viscosity of the linear carboxylic acid esters, they can effectively improve the conductivity of the electrolyte, thereby further improving the fast charging performance of the battery.

[0188] In some embodiments, the organic solvent includes a carbonate solvent, and the carbonate solvent includes a linear carbonate and a cyclic carbonate. Based on the total mass of the electrolyte, the mass ratio of the linear carbonate is 10% to 40%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc., or other unlisted values within the range of 10% to 40%.

[0189] In some embodiments, the cyclic carbonate includes one or more of ethylene carbonate and propylene carbonate, and the linear carbonate includes one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0190] In some embodiments, the linear carbonate includes dimethyl carbonate. Based on the total mass of the electrolyte, the mass ratio of dimethyl carbonate is 5% to 15%, such as 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc., or other unlisted values within the range of 5% to 15%.

[0191] When the above types and mass ratios of carbonates are used as organic solvents in the electrolyte, the side reactions and gas generation during the cycling of the battery can be improved, so that the battery can simultaneously have good cycling performance.

[0192] In some embodiments, the organic solvent includes dimethyl carbonate and a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to dimethyl carbonate is 2.0 to 7.0, such as 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, etc., or other unlisted values within the range of 2.0 to 7.0.

[0193] In some embodiments, the organic solvent includes dimethyl carbonate and a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to dimethyl carbonate is 3.0 to 6.0.

[0194] When dimethyl carbonate and linear carboxylic acid ester in the above mass ratio are used as organic solvents in the electrolyte at the same time, through the combination of the two solvents, the fast charging performance and cycling performance of the battery can be further improved simultaneously.

[0195] In some embodiments, the electrolyte further includes a lithium salt, such as at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0196] In some embodiments, based on the total mass of the electrolyte, the mass percentage of the lithium salt is 13% to 20%, such as 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc., or other unlisted values within the range of 13% to 20%.

[0197] In some embodiments, the lithium salt includes at least two of lithium hexafluorophosphate LiPF 6 and fluorosulfonylimide salts, and the fluorosulfonylimide salts include one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0198] Lithium hexafluorophosphate is not prone to gas generation during cycling, which can further improve the cycling performance of the battery; while the fluorosulfonylimide salt has strong dissociation ability, which can further improve the fast charging performance of the battery.

[0199] In some embodiments, the lithium salt includes lithium hexafluorophosphate LiPF 6 and lithium bis(fluorosulfonyl)imide LiFSI.

[0200] In some embodiments, in the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF 6 to lithium bis(fluorosulfonyl)imide LiFSI 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, etc., or other unlisted values within the range of 1.2:1 to 2:1.

[0201] When lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide within the above mass ratio range are used in the electrolyte at the same time, the fast charging performance and cycling performance of the battery can be further improved simultaneously.

[0202] In some embodiments, the electrolyte further includes additives. For example, the additives can include anode film-forming additives, cathode film-forming additives, and can also include additives that can improve certain properties of the battery, such as additives for improving the overcharging performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0203] In some embodiments, the electrolyte includes carbonate additives, and the carbonate additives include fluoroethylene carbonate (FEC) and vinylene carbonate (VC).

[0204] In some embodiments, based on the total mass of the electrolyte, the mass ratio of the carbonate additives is 0.5% to 7%, such as 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 6.5%, 7%, etc., or other unlisted values within the range of 0.5% to 7%.

[0205] In the battery cell provided by the present application, carbonate additives with a mass ratio within the above range, such as fluoroethylene carbonate and vinylene carbonate, are further added to the electrolyte. They can form a SEI film on the surface of the negative electrode, thereby reducing the side reactions occurring between the electrode sheet and the electrolyte, and further enabling the battery to have good cycle performance.

[0206] In some embodiments, the electrolyte includes vinylene carbonate (VC). Based on the total mass of the electrolyte, the mass ratio of vinylene carbonate (VC) in the electrolyte is 0.5% to 2%, such as 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%, etc., or other unlisted values within the range of 0.5% to 2%.

[0207] When vinylene carbonate within the above mass ratio range is added as an additive to the electrolyte, the formed SEI film is relatively stable, which is beneficial to further improving the cycle performance of the battery.

[0208] In some embodiments, the electrolyte includes fluoroethylene carbonate (FEC). Based on the total mass of the electrolyte, the mass ratio of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 1%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc., or other unlisted values within the range of 0.1% to 1%.

[0209] When fluoroethylene carbonate within the above mass ratio range is added as an additive to the electrolyte, the formed SEI film has a low impedance, which can further improve the fast charging performance of the battery.

[0210] [Separator membrane] In some embodiments, the battery cell further includes a separator membrane. The present application does not particularly limit the type of the separator membrane, and any well-known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

[0211] In some embodiments, the material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0212] [Battery cell] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator membrane can be made into an electrode assembly by a winding process or a stacking process.

[0213] In some embodiments, the positive current collector, the separator, the negative current collector, and the separator are stacked in sequence 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 Figure 4 shown.

[0214] In some embodiments, the battery cell further includes a top cover, and the top cover includes electrode terminals with opposite polarities for electrically connecting to the positive electrode tab or the negative electrode tab.

[0215] In some embodiments, as shown in combination with Figure 4 FIG. 20, the battery cell 10 further includes a top cover 13, and the top cover 13 includes two electrode terminals 131 with opposite polarities, one of which is a positive electrode terminal 131 for electrically connecting to the positive electrode tab 111b, and the other is a negative electrode terminal 131 for electrically connecting to the negative electrode tab 112b.

[0216] The wound positive electrode tabs 111b are aligned and stacked, having a relatively large connection area, so that the positive electrode tabs 111b can be directly electrically connected to the electrode terminals 131 without connecting the positive electrode tabs 111b to the electrode terminals 131 through a transition piece. Similarly, the wound negative electrode tabs 112b are aligned and stacked, having a relatively large connection area, so that the negative electrode tabs 112b can be directly electrically connected to the electrode terminals 131 without connecting the negative electrode tabs 112b to the electrode terminals 131 through a transition piece.

[0217] In a conventional battery, a transition piece is required to connect the electrode terminal and the electrode tab, but this will reduce the utilization rate of the electrode assembly and lower the battery energy density. When the above structure is adopted in the battery cell provided in the present application, canceling the setting of the transition piece can effectively solve this problem, reduce the battery internal resistance, and further improve the battery energy density and fast charging performance.

[0218] In some embodiments, the battery cell can include an outer package. The outer package can be used to encapsulate the above electrode assembly and electrolyte.

[0219] In some embodiments, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging 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. As plastics, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed, etc.

[0220] In some embodiments, as Figures 4 - 7 shown, the battery cell 10 further includes a housing 14, and the current collector 11 is disposed within the housing 14.

[0221] In some embodiments, as Figures 4 - 7 shown, the housing 14 is square, the thickness T of the housing is 30 mm to 55 mm, the width W is 150 mm to 250 mm, and the height H is 90 mm to 120 mm.

[0222] In some embodiments, the thickness T of the housing is 30 mm to 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 mm to 55 mm.

[0223] In some embodiments, the width W of the housing is 150 mm to 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 mm to 250 mm.

[0224] In some embodiments, the height H of the housing is 90 mm to 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 mm to 120 mm.

[0225] In some embodiments, the battery cell is configured to have a charging time of 10 min to 17 min when charging 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 min to 17 min.

[0226] The battery cell provided by the present application has excellent fast charging performance.

[0227] In some embodiments, the present application does not particularly limit the shape of the battery cell, and it can be cylindrical, square, or any other shape. For example, Figure 8The battery cell 5 is a square structure as an example. Optionally, the battery cell is a lithium-ion battery or a sodium-ion battery.

[0228] In some embodiments, referring to Figure 9 , the outer package may include a housing 51 and a cover plate 53. Among them, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate and the separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0229] In some embodiments, a battery device is provided. The battery device can be a battery module, a battery pack, an energy storage battery, etc. The above battery cells can be assembled into a battery module, and the number of battery cells included in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.

[0230] Figure 10 The battery module 4 is an example. Referring to Figure 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 way. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0231] Optionally, the battery module 4 may further include a housing having a receiving space, and a plurality of battery cells 5 are received in the receiving space.

[0232] In some embodiments, the above battery module can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.

[0233] Figure 11 and Figure 12 The battery pack 1 is an example. Referring to Figure 11 and Figure 12 , the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be covered on the lower box body 3 and 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 way.

[0234] [Power-consuming device] In addition, the present application also provides an electrical device, which includes at least one of the battery cells, battery modules, or battery packs provided by the present application. The battery cell, battery module, or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device can include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0235] As the electrical device, the battery cell, battery module, or battery pack can be selected according to its usage requirements.

[0236] Figure 13 Take an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the electrical device for the battery cell, a battery pack or a battery module can be adopted.

[0237] In some embodiments, the electrical device includes a vehicle, and the length direction of the electrode assembly is placed along the traveling direction of the vehicle.

[0238] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires thinness and lightness, and a battery cell can be used as the power source.

[0239] Embodiment Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0240] Embodiment 1 1) Negative electrode sheet Mix artificial graphite as the negative electrode active material, acetylene black as the conductive agent, styrene-butadiene rubber as the binder, and sodium carboxymethyl cellulose as the thickener in a mass ratio of 96:1:2:1. Then add deionized water as the solvent and stir to form a negative electrode slurry. Coat the negative electrode slurry evenly on the negative electrode current collector copper foil, and after drying and cold pressing, obtain the negative electrode sheet; wherein, the thickness of the negative electrode current collector copper foil is 4.5 μm, the single-sided areal density of the negative electrode sheet is 0.155 g / 1540 mm 2 , and the tap density of the negative electrode sheet is 1.47 g / cm 3, the size of the negative electrode film layer in the first direction is 92 mm; the volume particle size Dv50 of artificial graphite is 11 μm, and the graphitization degree is 94.1%.

[0241] 2) Positive electrode sheet Mix the positive electrode active material lithium iron phosphate (LFP), binder polyvinylidene fluoride, and conductive agent acetylene black in a ratio of 97:2:1, and then add the solvent N-methylpyrrolidone (NMP) and stir to form a positive electrode slurry; coat the positive electrode slurry evenly on the positive electrode current collector aluminum foil, and after drying and cold pressing, obtain the positive electrode sheet. Among them, the thickness of the positive electrode current collector aluminum foil is 13 μm, and the single-sided surface density of the positive electrode sheet is 0.341 mg / 1540 mm 2 , the tap density of the positive electrode sheet is 2.51 g / cm 3 , the size of the positive electrode film layer along the first direction is 88.5 mm; the positive electrode active material includes first lithium-containing phosphate particles with a longest diameter of 0.3 μm - 1 μm and second lithium-containing phosphate particles with a longest diameter of 3 μm - 5 μm. In the longitudinal section of the positive electrode sheet, select any area that contains at least 100 olivine-structured lithium-containing phosphates. In the said any area, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

[0242] 3) Electrolyte Mix dimethyl carbonate (DMC), ethyl acetate (EA), ethylene carbonate (EC), and ethyl methyl carbonate (EMC) evenly in a mass ratio of 10:50:35:5 to obtain an electrolyte solvent. Include lithium hexafluorophosphate (LiPF 6 ) and lithium bis(fluorosulfonyl)imide (LiFSI) as lithium salts, and stir well until they are completely dissolved. Include vinylene carbonate (VC) with a mass percentage of 0.7% and fluoroethylene carbonate (FEC) with a mass percentage of 0.3% relative to the total mass of the electrolyte. Based on the total mass of the electrolyte, the mass fraction of lithium hexafluorophosphate (LiPF 6 ) is 8.9%; the mass fraction of lithium bis(fluorosulfonyl)imide LiFSI is 4.6%, and the lithium ion conductivity of the electrolyte is 14.5 mS / cm.

[0243] 4) Separator Use a commercially available polyethylene microporous film with a thickness of 7 μm and an average pore diameter of 80 nm as the separator.

[0244] 5) Battery cell The positive electrode tab and the negative electrode tab are cut. The distance between the center lines of two adjacent tabs on the positive electrode tab is 316 mm, and the distance between the center lines of two adjacent tabs on the negative electrode tab is 314 mm. The positive electrode tab, the separator, and the negative electrode tab are stacked and wound in sequence to obtain a wound electrode assembly, such that each layer of the positive electrode tab and the negative electrode tab in the electrode assembly has at least one tab. The electrode assembly is placed into a square aluminum outer package with a thickness of 50 mm, a width of 208 mm, and a height of 103 mm, and electrolyte is injected after drying. Through processes such as encapsulation, standing, formation, aging, secondary encapsulation, and capacity measurement, a battery cell is obtained, and the tab of the battery cell is connected to the cover plate.

[0245] Examples 2 to 3 The battery cells of Examples 2 to 3 are basically similar to those of Example 1, except that the widths W 1 and W 2 of the positive electrode film layer and the negative electrode film layer are adjusted, so as to adjust the value of W 2 -W 1 . The specific values are shown in Tables 1 to 4.

[0246] Examples 4 to 6 The battery cells of Examples 4 to 6 are basically similar to those of Example 1, except that the areal density of the single-sided negative electrode film layer and the areal density of the single-sided positive electrode film layer are adjusted. The specific values are shown in Tables 1 to 4.

[0247] Examples 7 to 10 The battery cells of Examples 7 to 10 are basically similar to those of Example 1, except that the types or contents of the organic solvent and the lithium salt in the electrolyte are changed. The specific values are shown in Tables 1 to 4.

[0248] Example 11 The battery cell of Example 11 is basically similar to that of Example 1, except that double-layer coating is used for the negative active material. The method is as follows: artificial graphite with a Dv50 particle size of 13 μm is used as the lower layer, and artificial graphite with a Dv50 particle size of 10 μm is used as the upper layer, and they are uniformly coated on the negative current collector copper foil, and after drying and cold pressing, a negative electrode tab is obtained. The specific values are shown in Tables 1 to 4.

[0249] Comparative Examples 1 to 2 Comparative Examples 1 to 2 are basically similar to Example 1, except that the widths W 1 and W 2 of the positive electrode film layer and the negative electrode film layer are adjusted, so as to adjust the value of W 2 -W 1 . The specific values are shown in Tables 1 to 4.

[0250] Comparative Examples 3 to 4 Comparative Examples 3 to 4 are basically similar to Example 1, except that the areal density of the single-sided positive electrode tab and the single-sided negative electrode tab. The specific values are shown in Tables 1 to 4.

[0251] I. Performance Test 1. DC Internal Resistance For the DC internal resistance DCR test of a single battery cell, the method in GB / T 31467 "Performance Test Specification for High-Power Lithium-Ion Power Batteries for HEV" can be referred to. For example, at room temperature, charge the single battery cell to 3.65V at a constant current of 0.33C, let it stand for 1 min, then charge it to 3.65V at a constant current of 0.1C, let it stand for 30 min, discharge it at a constant current of 0.33C to 2.0V, record the discharge capacity A0 at this time, with the unit of Ah. Then charge it at a constant current of 0.33C for 0.5A0Ah to adjust the SOC to 50%. After leaving the single battery cell at 25°C for 2 h, discharge it at a constant current of 3C for 10 s, record ΔU_discharge and ΔI_discharge, and calculate the discharge DCR data of the lithium-ion battery through the following formula: R_discharge = ΔU_discharge / ΔI_discharge, where ΔU_discharge represents the voltage change within the first 10 s of discharge, and ΔI_discharge represents the current value within the first 10 s of discharge.

[0252] 2. Charging Time at 10% - 80% SOC Charging time test: ① Voltage calibration: 1) The positive electrode sheet, negative electrode sheet, separator, and electrolyte in the example or comparative example are prepared into a laminated three-electrode battery and left to stand at 25°C for 30 min; 2) At 25°C, the battery cell is charged at 0.33C to the charging cut-off voltage of 3.65V, and then constant voltage charging is continued at this charging cut-off voltage until the current is 0.05C, and the charging is cut off (where C represents the rated capacity of the battery cell); 3) Leave to stand at 25°C for 1 h; 4) At 25°C, the battery cell is discharged at 0.33C to the discharge cut-off voltage of 2.5V, and record the total discharge capacity C0 discharged by the battery cell; 5) Leave to stand at 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 are prepared into a laminated three-electrode battery and left to stand for 30 min; 2) DC discharge at 0.33C0 to the discharge cut-off voltage of 2.5V, corresponding to 0% SOC at this time; 3) Leave to stand for 5 min; 4) Constant current charge at 5C0 until the negative electrode potential is 0V, and read the capacity C1 at this time, corresponding to C1 / C0 SOC at this time; 5) Leave to stand for 5 min; 6) Constant current charge at 4.5C0 until the negative electrode potential is 0V, and read the capacity C2 at this time, corresponding to C2 / C0 SOC at this time; 7) Leave to stand for 5 min; 8) Constant current charge at 4C0 until the negative electrode potential is 0V, and read the capacity C3 at this time, corresponding to C3 / C0 SOC at this time; 9) Leave to stand for 5 min; 10) Constant current charge at 3C0 until the negative electrode potential is 0V, and read the capacity C4 at this time, corresponding to C4 / C0 SOC at this time; 11) Leave to stand for 5 min; 12) Constant current charge at 2C0 until the negative electrode potential is 0V, and read the capacity C5 at this time, corresponding to C5 / C0 SOC at this time; 13) Leave to stand for 5 min; 14) Constant current charge at 1C0 until the negative electrode potential is 0V, and read the capacity C6 at this time, corresponding to C6 / C0 SOC at this time; 15) Leave to stand for 5 min; 16) Constant current charge at 0.8C0 until the negative electrode potential is 0V, and read the capacity C7 at this time, corresponding to C7 / C0 SOC at this time; 17) Leave to stand for 5 min; 18) Constant current charge at 0.5C0 until the negative electrode potential is 0V, and read the capacity C8 at this time, corresponding to C8 / C0 SOC at this time; 19) Leave to stand for 5 min; 20) Constant current charge at 0.33C0 until the negative electrode potential is 0V, and read the capacity C9 (i.e., C0) at this time, corresponding to 100% SOC. The required charging time is obtained by adding up the total charging time during the charging process from 10% SOC to 80% SOC.

[0253] 3. Volume energy density At 25 °C, the battery cell is discharged at a constant current of 0.33C to 2.5V, left standing for 5 minutes, charged at a constant current of 0.33C to the upper cut-off voltage of 3.65V, then charged at a constant voltage until the current reaches 0.05C, and left standing for 5 minutes; it is discharged at a constant current of 0.33C to the cut-off voltage of 2.5V, and the discharge capacity at this time is recorded to obtain the discharge energy E0. The volume energy density (Wh / L) = discharge energy E0 / monomer volume (L).

[0254] 4. Cycle performance At 25 °C, it is charged at a charging rate of 0.5C to 3.65V, then charged at a constant voltage of 3.65V until the current reaches 0.05C, left standing for 10 minutes, and then discharged at a discharge rate of 1C to 2.5V, left standing for 10 minutes. One charge-discharge cycle as described above is considered one cycle, and the test is stopped until the battery capacity decays to 80% of the nominal capacity, denoted as the cycle count @80% SOH.

[0255] II. Analysis of test results of each example and comparative example The battery cells of each example and comparative example were prepared respectively according to the above method, and various performance parameters were measured. The results are shown in Tables 1 to 5 below.

[0256] Table 1 Electrode sheet preparation parameters

[0257] Table 2 Electrode sheet preparation parameters

[0258] Table 3 Electrolyte preparation parameters

[0259] Table 4 Electrolyte preparation parameters

[0260] Table 5 Battery performance parameters

[0261] In the battery cells of Examples 1 to 11, the areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25mm 2 to 0.4 g / 1540.25mm 2 ; the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2 ; along the first direction, the size of the positive electrode film layer is W 1 mm, and the size of the negative electrode film layer is W 2 mm, W 2 >W 1 and W2 The difference from W 1 is 3 mm to 5 mm; thus, the battery monomers prepared in Examples 1 to 11 all have excellent fast charging performance, energy density, cycle performance, and low DC internal resistance.

[0262] For Comparative Examples 1 to 2, the sizes of the positive and negative electrode film layers, W 2 and W 1 have a difference exceeding 3 mm to 5 mm, where: in Comparative Example 1, the difference between W 2 and W 1 is too small, while in Comparative Example 2, the difference between W 2 and W 1 is too large.

[0263] From the comparison between Comparative Examples 1 to 2 and Examples 1 to 11, it can be seen that when the difference between the sizes of the positive and negative electrode film layers, W 2 and W 1 is below the range of 3 mm, the cycle performance of the battery monomer will deteriorate; while when the difference between the sizes of the positive and negative electrode film layers, W 2 and W 1 is greater than the range of 5 mm, the energy density of the battery monomer will deteriorate; therefore, the difference between the sizes of the positive and negative electrode film layers, W 2 and W 1 needs to be in the range of 3 mm to 5 mm to balance the improvement of the cycle performance and energy density of the battery. When exceeding this range, the comprehensive performance of the battery is poor.

[0264] For Comparative Examples 3 to 4, the areal densities of the positive and negative electrode film layers respectively exceed the ranges of 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 , 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 , where: in Comparative Example 3, the areal densities of the single-sided positive electrode film layer and the single-sided negative electrode film layer are too large, while in Comparative Example 4, the areal densities of the single-sided positive electrode film layer and the single-sided negative electrode film layer are too small.

[0265] From the comparison between Comparative Examples 3 to 4 and Examples 1 to 11, it can be seen that when the areal density of the positive and negative electrode film layers is too large, the fast charging performance, DC internal resistance, and cycle performance of the battery monomer will deteriorate; while when the areal density of the positive and negative electrode film layers is too large, the energy density of the battery monomer will deteriorate; therefore, the areal densities of the positive and negative electrode film layers are respectively in the ranges of 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 , 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2When within the range, it takes into account improving the fast charging performance, DC internal resistance, cycle performance and energy density of the battery. When exceeding this range, the comprehensive performance of the battery is poor.

[0266] In Examples 1 to 3, the size W of the positive and negative electrode film layers 2 and W 1 The difference is within the range of 3 mm to 5 mm. The battery cells prepared therefrom can take into account excellent energy density, fast charging performance, cycle performance, and low DC internal resistance. In addition, the results also show that when the difference between W 2 and W 1 gradually increases within the range of 3 mm to 5 mm, the cycle performance, fast charging performance, and DC internal resistance of the battery are improved to a certain extent, but the energy density decreases to a certain extent; while when the difference between W 2 and W 1 gradually decreases within the range of 3 mm to 5 mm, the energy density of the battery is improved to a certain extent, but the improvement of the cycle performance, fast charging performance, and DC internal resistance is limited.

[0267] In Examples 1, 4 to 6, the areal density of the positive and negative electrode film layers is respectively within the range of 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 , 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 . The battery cells prepared therefrom can take into account excellent energy density, fast charging performance, cycle performance, and low DC internal resistance. In addition, the results also show that when the areal density of the positive and negative electrode film layers gradually decreases within the above range, the cycle performance, fast charging performance, and DC internal resistance of the battery are improved to a certain extent, but the energy density decreases to a certain extent; while when the areal density of the positive and negative electrode film layers gradually increases within the above range, the energy density of the battery is improved to a certain extent, but the improvement of the cycle performance, fast charging performance, and DC internal resistance is limited.

[0268] Therefore, it can be seen from the results of Examples 1 to 6 that the difference between the size W 2 of the positive and negative electrode film layers and W 1 needs to be within the range of 3 mm to 5 mm, and it is necessary to match the areal density of the positive and negative electrode film layers to be respectively within the range of 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 , 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 so as to be able to take into account improving the energy density, fast charging performance, cycle performance, and DC internal resistance of the battery and make the battery have excellent comprehensive performance.

[0269] In Examples 1, 7 to 10, the electrolyte adopted the following formula, and the battery monomers prepared therefrom could take into account excellent energy density, fast charging performance, cycling performance, and low DC internal resistance: The organic solvent adopted a linear carboxylic acid ester (such as ethyl acetate) with a mass fraction of 40% to 75%, a linear carbonate (such as DMC, EMC) with a mass fraction of 10% to 40%, and a cyclic carbonate (such as ethylene carbonate), wherein the mass fraction of dimethyl carbonate was 5% to 15%, and the mass ratio of the linear carboxylic acid ester (such as ethyl acetate) to dimethyl carbonate was 2.0 to 7.0; The lithium salt adopted LiPF 6 and LiFSI, and the mass ratio of LiPF 6 to LiFSI was 1.2:1 to 2:1.

[0270] Meanwhile, by comparing Examples 1, 7, and 8, it can be seen that: as the proportion of the linear carboxylic acid ester (such as ethyl acetate) and LiFSI added to the electrolyte gradually increases, the fast charging performance and DC internal resistance of the battery are further improved; while as the proportion of the linear carbonate (such as DMC) and LiPF 6 added to the electrolyte gradually increases, the cycling performance of the battery is further improved.

[0271] Meanwhile, by comparing Examples 1, 9, and 10, it can be seen that: when there is only a linear carboxylic acid ester (such as ethyl acetate) in the organic solvent of the electrolyte and no carbonate, and there is only LiFSI in the lithium salt and no LiPF 6 , the fast charging performance and DC internal resistance of the battery are further improved, but the cycling performance of the battery is poor; when there is only a linear carbonate (such as DMC) in the organic solvent of the electrolyte and no linear carboxylic acid ester, and there is only LiPF 6 in the lithium salt and no LiFSI, the cycling performance of the battery is further improved, but the improvement of the fast charging performance and DC internal resistance is limited. Therefore, when the linear carbonate and linear carboxylic acid ester with the above mass ratio are used as the organic solvent in the electrolyte at the same time, and LiPF 6 and LiFSI with the above mass ratio are used as the lithium salt at the same time, through the mutual combination of various solvents and lithium salts, the fast charging performance, DC internal resistance, and cycling performance of the battery can be further taken into account and improved, making the comprehensive performance of the battery better.

[0272] In Embodiment 1 and Embodiment 11, at least one layer of graphite is included in the negative electrode film layer as the negative electrode active material, and its average particle size Dv50 is in the range of 8 μm to 15 μm. The prepared battery monomer can take into account excellent energy density, fast charging performance, cycling performance, and low DC 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 with different particle sizes as the negative electrode active material layers (the first negative electrode active material layer is disposed on the surface of the negative electrode current collector, the second negative electrode active material layer is disposed 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 DC internal resistance of the battery can be further taken into account, making the comprehensive performance of the battery better.

[0273] In Embodiments 1 to 11, as Figure 2 shown, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphates in the positive electrode film layer all include 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. The prepared battery monomer can take into account excellent energy density, fast charging performance, cycling performance, and low DC internal resistance.

[0274] In Embodiments 1 to 11, when the ratio of the single-sided 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 plate is 2.3 g / cm 3 to 2.6 g / cm 3 or the compaction density of the negative electrode plate is 1.3 g / cm 3 to 1.6 g / cm 3 the prepared battery monomer can take into account excellent energy density, fast charging performance, cycling performance, and low DC internal resistance.

[0275] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same function and effect as the technical idea within the technical solution scope of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various deformations that those skilled in the art can think of are applied to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of this application.

Claims

1. A battery cell, characterized in that: Including positive electrode and negative electrode, The positive electrode plate comprises a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, and the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, wherein: The positive electrode film layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, and the surface density of the positive electrode film layer on a single side is 0.33 g / 1540.25 mm 2 Up to 0.4g / 1540.25mm 2 The surface density of the negative electrode film layer on one side is 0.15g / 1540.25mm 2 Up to 0.19 g / 1540.25 mm 2 ; The positive current collector includes a positive current collecting portion and at least two positive electrode tabs arranged on the same side of the positive current collecting portion, and the positive electrode tab extends from the positive current collecting portion along a first direction; the negative current collector includes a negative current collecting portion and at least two negative electrode tabs arranged on the same side of the negative current collecting portion, and the negative electrode tab extends from the negative current collecting portion along a 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.

2. The battery cell according to claim 1, characterized in that: The surface density of the positive electrode film layer on one side is 0.335g / 1540.25mm 2 Up to 0.38 g / 1540.25 mm 2 The surface density of the negative electrode film layer on one side is 0.15 g / 1540.25 mm 2 Up to 0.165 g / 1540.25 mm 2 .

3. The battery cell according to claim 1, characterized in that: The compaction density of the positive electrode sheet is 2.3 g / cm 3 Up to 2.6g / cm 3 .

4. The battery cell according to claim 1, characterized in that: The compaction density of the positive electrode sheet is 2.4 g / cm 3 Up to 2.55g / cm 3 .

5. The battery cell according to claim 1, characterized in that: The compaction density of the negative electrode sheet is 1.3 g / cm 3 Up to 1.6g / cm 3 .

6. The battery cell according to claim 1, characterized in that: The compaction density of the negative electrode sheet is 1.35 g / cm 3 Up to 1.55g / cm 3 .

7. The battery cell according to claim 1, characterized in that: The negative electrode film layer includes 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 includes graphite.

8. The battery cell according to claim 7, characterized in that: 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%-95%.

11. The battery cell according to claim 1, characterized in that: The negative electrode film layer includes a first negative electrode active material layer arranged on the surface of the negative electrode 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 collector, the negative electrode active material in the first negative electrode active material layer includes a first artificial graphite, the negative electrode active material in the second negative electrode active material layer includes 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 according to claim 11, characterized in that: The average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

13. The battery cell according to claim 11, characterized in that: The average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

14. The battery cell according to claim 11, characterized in that: The average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

15. The battery cell according to claim 1, characterized in that: The thickness of the negative electrode current collector is 4-6 μm.

16. The battery cell according to claim 1, characterized in that: 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 according to claim 1, characterized in that: 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 according to claim 1, characterized in that: The battery cell includes an electrolyte, the electrolyte contains an organic solvent, and the organic solvent includes a carboxylate solvent and a carbonate solvent.

19. The battery cell according to claim 18, characterized in that: The organic solvent includes a linear carboxylic acid ester, and the mass proportion of the linear carboxylic acid ester is 40% to 75% based on the total mass of the electrolyte.

20. The battery cell according to claim 19, characterized in that: The linear carboxylic acid ester has a general structural formula of R1-COO-R2, wherein R1 and R2 each independently include one or more of a C1-C5 alkyl group and a C1-C5 halogenated alkyl group.

21. The battery cell according to claim 20, characterized in that: The linear carboxylic acid ester includes one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

22. The battery cell according to any one of claims 18 to 21, characterized in that: The organic solvent includes a carbonate solvent, and the carbonate solvent includes a linear carbonate and a cyclic carbonate. Based on the total mass of the electrolyte, the mass proportion of the linear carbonate is 10% to 40%.

23. The battery cell according to claim 22, characterized in that: The cyclic carbonate includes one or more of ethylene carbonate and propylene carbonate, and the linear carbonate includes one or more of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

24. The battery cell according to claim 23, characterized in that: The linear carbonate includes dimethyl carbonate, and based on the total mass of the electrolyte, the mass proportion of the dimethyl carbonate is 5% to 15%.

25. The battery cell according to claim 18, characterized in that: 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 according to claim 25, characterized in that: The mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.

0.

27. The battery cell according to claim 18, characterized in that: The electrolyte includes a lithium salt, and the mass proportion of the lithium salt is 13% to 20% based on the total mass of the electrolyte.

28. The battery cell according to claim 27, characterized in that: The lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and fluorine-containing sulfonyl imide salts, and the fluorine-containing sulfonyl imide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

29. The battery cell according to claim 27, characterized in that: The lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide LiFSI.

30. The battery cell according to claim 29, characterized in that In the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bis(fluorosulfonyl)imide LiFSI is 1.2:1 to 2:

1.

31. The battery cell according to claim 18, characterized in that The electrolyte further comprises an additive, and the additive comprises a carbonate additive.

32. The battery cell according to claim 31, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the carbonate additive in the electrolyte is 0.5% to 7%.

33. The battery cell according to claim 31 or 32, characterized in that: The carbonate additives include vinylene carbonate VC and fluoroethylene carbonate FEC.

34. The battery cell according to claim 31 or 32, characterized in that: The additive includes vinylene carbonate VC; based on the total mass of the electrolyte, the mass proportion of vinylene carbonate VC in the electrolyte is 0.5% to 2%.

35. The battery cell according to claim 31 or 32, characterized in that: The additive includes fluoroethylene carbonate (FEC); based on the total mass of the electrolyte, the mass proportion of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 1%.

36. The battery cell according to claim 1, characterized in that The general formula of the lithium-containing phosphate is as shown in Formula I: Li x A y Me a M b P 1-c X c Y z Formula I Among them, 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, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

37. The battery cell according to claim 36, characterized in that: M includes one or more of Al, Ti, V, and Mg.

38. The battery cell according to claim 36 or 37, characterized in that: The positive electrode active material satisfies at least one of the following: (1) The positive electrode active material contains Al element, the mass content of which is 0.01-0.05%, based on the total mass of the positive electrode active material; (2) The positive electrode active material contains Ti element, the mass content of which is 0.01-0.03%, based on the total mass of the positive electrode active material; (3) The positive electrode active material contains V element, the mass content of which 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, with a mass content of 0.001-0.01% based on the total mass of the positive electrode active material.

39. The battery cell according to claim 1, characterized in that: In a cross section of the positive electrode film layer along a 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 according to claim 39, characterized in that 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 according to claim 1, characterized in that The distance between the center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction; and / or, The distance between the center lines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction.

42. The battery cell according to claim 41, characterized in that The distance between the center lines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or, The distance between the center lines of two adjacent negative electrode ears is 20 mm to 330 mm.

43. The battery cell according to claim 41, characterized in that The battery cell further includes a top cover, wherein the top cover includes a positive electrode terminal and a negative electrode terminal with opposite polarities, wherein the positive electrode terminal and the negative electrode terminal are respectively used to be electrically connected to the positive electrode tab and the negative electrode tab.

44. The battery cell according to claim 1, characterized in that The battery shell is square, with 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 according to claim 1, characterized in that The battery cell is configured to be charged from 10% SOC to 80% SOC in a charging time of 10 to 17 minutes at room temperature.

46. ​​A battery device, characterized in that: Comprising the battery monomer described in any one of claims 1 to 45, the battery device is at least one of a battery module, a battery pack, and an energy storage device.

47. An electrical device, characterized in that: A battery cell comprising any one of claims 1 to 45 or a battery device according to claim 46.

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