Battery cell, battery device, and electric device

Abstract

A battery cell, a battery device, and an electric device. In the battery cell, a positive electrode active material comprises an olivine-structured lithium-containing phosphate, and in the cross section of a positive electrode film layer in the thickness direction, the olivine-structured lithium-containing phosphate contains first lithium-containing phosphate particles having a maximum diameter of 0.05 μm to 0.3 μm, and second lithium-containing phosphate particles having a maximum diameter of 1 μm to 3 μm; the average particle size Dv50 of a negative electrode active material is 8 μm to 15 μm, and the negative electrode active material comprises graphite.

Description

Battery cell, battery device and electric device TECHNICAL FIELD

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

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

[0003] SUMMARY

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

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a battery cell, comprising a positive electrode sheet, a negative electrode sheet and a separator film between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, the positive electrode active material comprising lithium-containing phosphate with olivine structure; in the cross section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate with olivine structure comprises 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 negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, the negative electrode film layer comprising a negative electrode active material, the average particle size Dv50 of the negative electrode active material being 8 μm to 15 μm, the negative electrode active material comprising graphite.

[0006] The application improves the transmission path of lithium ions in the negative active material during charging by using small particle size negative active material, which is beneficial to improve the fast charging capacity of the battery monomer. However, when the fast charging capacity of the battery monomer is improved, the corresponding charging current it can withstand is also improved. At this time, if the positive active material is not reasonably arranged, it will cause the internal heat of the battery monomer to gather during fast charging, the internal temperature of the battery rises, and the electrolyte gas is generated, the impedance of the solid electrolyte interface film (SEI film) of the negative electrode increases and other adverse reactions, thereby increasing the internal resistance of the battery and affecting the cycle performance of the battery monomer. The application reasonably selects different sizes of lithium-containing phosphates as positive active materials, effectively reduces the heat accumulation in the battery monomer by mixing the particles of different sizes, reduces the internal temperature rise of the battery monomer, and inhibits the growth of the direct current resistance (DCR) of the battery monomer; At the same time, the energy density of the battery monomer is improved.

[0007] In the battery monomer provided by the application, when the positive active material contains lithium-containing phosphate particles with a longest diameter of 0.05 to 0.3 μm, the direct current resistance of the battery monomer can be further improved, thereby further reducing the heat generation of the battery, and the battery has excellent safety performance.

[0008] In the battery monomer provided by the application, when the lithium-containing phosphate as the positive active material contains first lithium-containing phosphate particles with a longest diameter of 0.05 to 0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1 to 3 μm, the compaction density of the pole piece can be effectively improved by grading the size of the particles, thereby the battery monomer also has a high energy density.

[0009] In any embodiment, the average particle size Dv50 of the negative active material is 9.5 to 11.5 μm.

[0010] When the negative active material (such as graphite) has a particle size in the above range, the fast charging performance and direct current resistance of the battery can be further improved, and the battery also has good cycle performance.

[0011] In any embodiment, the specific surface area of the negative active material is 3 m 2 / g to 8 m 2 / g.

[0012] In any embodiment, the specific surface area of the negative active material is 4 m 2 / g to 6 m 2 / g.

[0013] When the specific surface area of the negative active material (e.g. graphite) is within the above range, the speed of lithium ion intercalation and deintercalation between graphite layers can be further accelerated, thereby further improving the fast-charging performance of the battery.

[0014] In any embodiment, 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.

[0015] When the number of the first lithium-containing phosphate particles having a longest diameter of 0.05 μm to 0.3 μm is greater than the number of the second lithium-containing phosphate particles having a longest diameter of 1 μm to 3 μm, the DC internal resistance and the fast-charging performance of the battery can be further improved.

[0016] In any embodiment, the olivine-structured lithium-containing phosphate has a general formula as shown in Formula I,

[0017] Li x A y Me a M b P 1-c X c Y z Formula I,

[0018] wherein 0.1≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A comprises one or more of Na, K, Mg; Me comprises one or more of Mn, Fe, Co, Ni; M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X comprises one or more of S, Si, Cl, B, C, N; and Y comprises one or more of O, F.

[0019] When the lithium-containing phosphate as the positive active material has the above general formula, the energy density of the battery can be further improved.

[0020] In any embodiment, M comprises one or more of Al, Ti, V, Mg.

[0021] In any embodiment, the positive active material satisfies at least one of the following conditions:

[0022] (1) the positive active material contains Al element, and the mass content is 0.01-0.05%, based on the total mass of the positive active material;

[0023] (2) the positive electrode active material contains Ti element, the mass content is 0.01-0.03%, based on the total mass of the positive electrode active material;

[0024] (3) the positive electrode active material contains V element, the mass content is 0.1-0.3%, based on the total mass of the positive electrode active material;

[0025] (4) the positive electrode active material contains Mg element, the mass content is 0.001-0.01%, based on the total mass of the positive electrode active material.

[0026] When the lithium-containing phosphate as the positive electrode active material contains Al, Ti, V, Mg and other elements, the specific capacity can be further improved.

[0027] In any embodiment, the compaction density of the positive electrode sheet is 2.3g / cm 3 to 2.6g / cm 3 .

[0028] In any embodiment, the compaction density of the positive electrode sheet is 2.4g / cm 3 to 2.55g / cm 3 .

[0029] When the compaction density of the positive electrode sheet is in the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0030] In any embodiment, the areal density of the positive electrode film layer on one side is 0.33g / 15 40.25mm 2 to 0.4g / 15 40.25mm 2 .

[0031] In any embodiment, the areal density of the positive electrode film layer on one side is 0.335g / 15 40.25mm 2 to 0.38g / 15 40.25mm 2 .

[0032] In the battery provided by the present application, when the coating areal density of the positive electrode film layer is in the above range, the energy density of the battery can be further improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby further improving the fast charging performance of the battery.

[0033] In any embodiment, the thickness of the positive electrode current collector is 10-15μm.

[0034] In any embodiment, the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 5-12.

[0035] In any embodiment, the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 6 to 10.

[0036] In the battery cell provided by the present application, when the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is within the above range, the energy density and the fast-charging performance of the battery can be further improved.

[0037] In any embodiment, the compaction density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 .

[0038] In any embodiment, the compaction density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm 3 .

[0039] 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 the kinetic performance is ensured.

[0040] In any embodiment, the areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 .

[0041] In any embodiment, the areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.165 g / 15 40.25 mm 2 .

[0042] In the battery cell provided by the present application, when the areal density of the negative electrode film layer is within the above range, the energy density of the battery can be further improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby further improving the fast-charging performance of the battery.

[0043] In any embodiment, the thickness of the negative electrode current collector is 4 to 6 μm.

[0044] In any embodiment, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 12 to 20.

[0045] In any embodiment, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 13 to 20.

[0046] In the battery cell provided by the present application, when the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is within the above range, the energy density and the fast-charging performance of the battery can be further improved.

[0047] 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 a first artificial graphite, and the negative electrode active material in the second negative electrode active material layer includes a second artificial graphite, the average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

[0048] In any embodiment, the average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

[0049] In any embodiment, the average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

[0050] In any embodiment, the average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

[0051] In the battery cell provided in the present application, when the above-mentioned double-layer coating scheme is used in the negative electrode film layer, the kinetic performance of the battery can be further improved.

[0052] In any embodiment, the battery cell further includes an electrolyte, and the electrolyte contains an organic solvent, the organic solvent including a carboxylic acid ester solvent and a carbonate solvent.

[0053] In the battery cell provided in the present application, when the above-mentioned type of organic solvent is used in the electrolyte, the kinetic performance of the battery can be further improved.

[0054] In any embodiment, the organic solvent includes a linear carboxylic acid ester, and the mass fraction of the linear carboxylic acid ester is 40% to 75% based on the total mass of the electrolyte.

[0055] In any embodiment, 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 C1-C5 alkyl and C1-C5 halogenated alkyl.

[0056] 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.

[0057] When the above-mentioned type and mass fraction of linear carboxylic acid ester are used as the organic solvent in the electrolyte, because the linear carboxylic acid ester has the characteristic of low viscosity, it can effectively improve the electrolyte conductivity, thereby further improving the fast-charging performance of the battery.

[0058] In any embodiment, the organic solvent comprises a carbonate solvent, the carbonate solvent comprises a linear carbonate and a cyclic carbonate, the mass percentage of the linear carbonate is 10% to 40% based on the total mass of the electrolyte.

[0059] In any embodiment, the cyclic carbonate comprises one or more of ethylene carbonate, propylene carbonate, and the linear carbonate comprises one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0060] In any embodiment, the linear carbonate comprises dimethyl carbonate, and the mass percentage of the dimethyl carbonate is 5% to 15% based on the total mass of the electrolyte.

[0061] When the electrolyte uses the above type and mass percentage of carbonate as the organic solvent, the side reactions and the degree of gas production of the battery during the cycle process can be improved, so that the battery has good cycle performance.

[0062] In any embodiment, the organic solvent comprises dimethyl carbonate and linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 2.0 to 7.0.

[0063] In any embodiment, the organic solvent comprises dimethyl carbonate and linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.0.

[0064] When the electrolyte uses the above mass ratio of dimethyl carbonate and linear carboxylic acid ester as the organic solvent, the combination of the two solvents can further improve the fast charging performance and cycle performance of the battery.

[0065] In any embodiment, the electrolyte further comprises a lithium salt, and the mass percentage of the lithium salt is 13% to 20% based on the total mass of the electrolyte.

[0066] In any embodiment, the lithium salt comprises at least two of lithium hexafluorophosphate LiPF6 and fluorine-containing sulfonimide salt, and the fluorine-containing sulfonimide salt comprises one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis-trifluoromethylsulfonylimide LiTFSI.

[0067] Lithium hexafluorophosphate is not easy to produce gas during the cycle process, which can further improve the cycle performance of the battery; and the dissociation ability of the fluorine-containing sulfonimide salt is strong, which can further improve the fast charging performance of the battery.

[0068] In any embodiment, the lithium salt comprises lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonylimide LiFSI.

[0069] In any embodiment, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfonylimide LiFSI in the electrolyte is 1.2:1 to 2:1.

[0070] When lithium hexafluorophosphate and lithium bisfluorosulfonylimide in the above mass ratio range are used simultaneously in the electrolyte, the fast-charging performance and the cycle performance of the battery can be further improved.

[0071] In any embodiment, the electrolyte comprises a carbonate-based additive, and the carbonate-based additive comprises fluoroethylene carbonate FEC and vinylene carbonate VC.

[0072] In any embodiment, the mass fraction of the carbonate-based additive in the electrolyte is 0.5% to 7% based on the total mass of the electrolyte.

[0073] In the battery cell provided in the present application, the carbonate-based additive, such as fluoroethylene carbonate and vinylene carbonate, in the electrolyte has a mass fraction in the above range, which can form an SEI film on the negative electrode surface, thereby reducing the side reaction between the electrode and the electrolyte, and further improving the cycle performance of the battery.

[0074] In any embodiment, the electrolyte comprises vinylene carbonate VC, and the mass fraction of the vinylene carbonate VC in the electrolyte is 0.5% to 2% based on the total mass of the electrolyte.

[0075] When the vinylene carbonate in the above mass fraction range is added as an additive in the electrolyte, the SEI film formed thereby is stable, which is conducive to further improving the cycle performance of the battery.

[0076] In any embodiment, the electrolyte comprises fluoroethylene carbonate FEC, and the mass fraction of the fluoroethylene carbonate FEC in the electrolyte is 0.1% to 1% based on the total mass of the electrolyte.

[0077] When the fluoroethylene carbonate in the above mass fraction range is added as an additive in the electrolyte, the SEI film formed thereby has low impedance, which can further improve the fast-charging performance of the battery.

[0078] In any embodiment, the positive electrode current collector comprises 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 extending from the positive electrode current collecting portion along a first direction, wherein 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,

[0079] The negative current collector comprises a negative current collecting part and at least two negative tabs arranged on the same side of the negative current collecting part, and the negative tabs extend from the negative current collecting part along a first direction, wherein the distance between the center lines of two adjacent negative tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction.

[0080] In any embodiment, the distance between the center lines of two adjacent positive tabs is 20 mm to 330 mm; and / or,

[0081] The distance between the center lines of two adjacent negative tabs is 20 mm to 330 mm.

[0082] The battery cell provided in the present application can further improve the direct current resistance of the battery cell when the positive and negative current collectors comprise at least two tabs with the above structural characteristics, thereby further reducing the heat generation of the battery, and making the battery have better safety performance.

[0083] In any embodiment, the battery cell further comprises a top cover, and the top cover comprises 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 electrical connection with the positive tab and the negative tab.

[0084] In a conventional battery, a jumper is needed to connect the electrode terminal and the tab, but the utilization rate of the electrode assembly is lost, and the energy density of the battery is reduced. When the battery cell provided in the present application adopts the above structure, the setting of the jumper can effectively solve this problem, reduce the internal resistance of the battery, and further improve the energy density and fast charging performance of the battery.

[0085] In any embodiment, the size of the positive film layer along the first direction is W1 mm, and the size of the negative film layer along the first direction is W2 mm, wherein W2>W1, and the difference between W2 and W1 is 3 mm to 5 mm.

[0086] During the cycle process of the battery, lithium ions that cannot be timely embedded in the negative electrode may form lithium dendrites on the surface of the negative electrode, which deteriorates the cycle performance of the battery. When the size W2 of the negative film layer and the size W1 of the positive film layer have the above relationship in the battery cell provided in the present application, the formation of lithium dendrites on the surface of the negative electrode can be improved, so that the battery has good cycle performance at the same time.

[0087] In any embodiment, the battery cell further comprises a shell, and the shell is square, the thickness of the shell is 30 mm to 55 mm, the width of the shell is 150 mm to 250 mm, and the height of the shell is 90 mm to 120 mm.

[0088] When the shell with the above size range is adopted, the energy density can be improved, and the internal resistance of the battery can be reduced, so that the energy density and the fast charging performance of the battery are improved.

[0089] In any embodiment, the battery cell is configured to have a charging time of 10 min to 17 min from 10% SOC to 80% SOC at room temperature.

[0090] The battery cell provided in the application has excellent fast charging performance.

[0091] The second aspect of the application also provides a battery device, which comprises the battery cell of the first aspect of the application, and the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0092] The third aspect of the application also provides a power utilization device, which comprises the battery cell of the first aspect of the application or the battery device of the second aspect of the application. BRIEF DESCRIPTION OF DRAWINGS

[0093] FIG. 1 is a schematic diagram of the size of the electrode sheet film layer according to an embodiment of the application;

[0094] FIG. 2 is a schematic diagram of the size of the electrode sheet film layer according to an embodiment of the application;

[0095] FIG. 3 is a schematic diagram of the size of the electrode sheet film layer according to an embodiment of the application;

[0096] FIG. 4 is an electron microscope observation result diagram of the longitudinal section of the positive electrode sheet according to an embodiment of the application;

[0097] FIG. 5 is a schematic diagram of the electrode sheet according to an embodiment of the application;

[0098] FIG. 6 is an exploded view of the battery cell according to an embodiment of the application;

[0099] FIG. 7 is a schematic diagram of the battery cell according to an embodiment of the application;

[0100] FIG. 8 is a schematic diagram of the battery cell according to an embodiment of the application;

[0101] FIG. 9 is a schematic diagram of the battery cell according to an embodiment of the application;

[0102] FIG. 10 is a schematic diagram of the battery cell according to an embodiment of the application;

[0103] FIG. 11 is an exploded view of the battery cell according to an embodiment of the application shown in FIG. 10;

[0104] FIG. 12 is a schematic diagram of the battery module according to an embodiment of the application;

[0105] FIG. 13 is a schematic diagram of the battery pack according to an embodiment of the application;

[0106] Fig. 14 is an exploded view of the battery pack shown in Fig. 13;

[0107] Fig. 15 is a schematic view of a power consuming device using the battery cell of the embodiment of the present application as a power source.

[0108] Explanation of Reference Numerals:

[0109] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 case; 52 electrode assembly; 53 top cover assembly; 10 battery cell; 11 current collector; 11a current collecting portion; 111a positive electrode current collecting portion; 112a negative electrode current collecting portion; 11b tab; 111b positive electrode tab; 112b negative electrode tab; F1 first direction; W1 dimension of positive electrode film layer in the first direction; W2 dimension of negative electrode film layer in the first direction; L center line; 13 top cover; 131 electrode terminal; 14 case. DETAILED DESCRIPTION

[0110] Hereinafter, the embodiments of the battery cell and the power consuming device of the present application are specifically disclosed while appropriately referring to the drawings. However, there are cases where unnecessary detailed explanations are omitted. For example, there are cases where detailed explanations of matters that are already well known, repeated explanations of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following explanations are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0111] The "ranges" disclosed in the present application are defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The ranges defined in this manner can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" represents a shorthand manner of describing each and every number that is contained in the range, wherein "a" and "b" are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand manner of describing each and every one of those numbers. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0112] If there is no special indication, all the embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0113] If there is no special indication, all the technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0114] If there is no special indication, all the steps of the present application can be performed in sequence or randomly, and the preferred sequence is in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0115] If there is no special indication, the "includes" and "contains" mentioned in the present application are open, and can also be closed. For example, the "includes" and "contains" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0116] If there is no special indication, 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 one 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) and B is true (or exists); or A and B are both true (or exist).

[0117] In recent years, with the increasing demand for batteries as energy sources, higher requirements have been put forward for the comprehensive performance of batteries. Compared with ternary batteries of nickel-cobalt-manganese lithium, batteries of lithium iron phosphate have become the mainstream of the secondary battery market due to their low cost, good safety and good cycle performance, but the rate performance of lithium iron phosphate batteries has become a bottleneck for their wider adaptation, especially under the premise of higher demand for energy density, it is more difficult to improve the rate performance. The present application aims to obtain a battery with fast charging and good energy density by reasonably matching the particle sizes of the positive and negative electrodes of the lithium iron phosphate battery.

[0118] Based on this, the application provides a battery monomer, comprising a positive electrode sheet, a negative electrode sheet, and a separator film between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, the positive electrode active material comprising lithium-containing olivine phosphate; in a cross section of the positive electrode film layer along the thickness direction, the lithium-containing olivine phosphate comprises first lithium-containing olivine phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing olivine phosphate particles with a longest diameter of 1 μm to 3 μm; the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, the negative electrode film layer comprising a negative electrode active material, the negative electrode active material having an average particle size Dv50 of 8 μm to 15 μm, and the negative electrode active material comprising graphite.

[0119] As used herein, the "average particle size Dv50" refers to the particle size corresponding to a cumulative volume distribution percentage of 50% from the small particle size side in the particle size distribution of the particles. The determination method can refer to GB / T19077-2016 / ISO 13320:2009, and a Malvern 2000 (MasterSizer 2000) laser particle size analyzer is used for determination.

[0120] In some embodiments, since the first lithium-containing olivine phosphate and the second lithium-containing olivine phosphate have been sufficiently mixed and uniformly coated on the current collector to form the positive electrode film layer when preparing the slurry, the cross section of the positive electrode sheet along the thickness direction can represent the particle size and distribution of the lithium-containing olivine phosphate in the entire positive electrode sheet. When selecting the cross section, the middle and relatively flat cross section of the positive electrode sheet is preferred, so that the distribution of the lithium-containing olivine phosphate can be more clearly observed.

[0121] In some embodiments, the "longest diameter" refers to cutting the positive electrode sheet comprising the lithium-containing olivine phosphate particles along the thickness direction of the positive electrode sheet to expose the longitudinal section of the positive electrode film layer; and determining the longest diameter of the lithium-containing olivine phosphate particles by scanning electron microscopy (SEM) test on the longitudinal section of the positive electrode film layer.

[0122] Specifically, the maximum value of the distance between any two points on the outer peripheral edge line of the lithium-containing olivine phosphate particle is the "longest diameter" of the particle. In some embodiments, as shown in the longitudinal section of the positive electrode sheet along the thickness direction in FIG. 4, the longest diameter of the single particle satisfying the first lithium-containing olivine phosphate particle (0.05 μm to 0.3 μm) is shown, and the shortest diameter of the single particle satisfying the second lithium-containing olivine phosphate particle (1 μm to 3 μm) is also shown.

[0123] It should be noted that the first lithium-containing phosphate particle material with a smaller size of 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.

[0124] The second lithium-containing phosphate particle material with a larger size of 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.

[0125] The two size ranges of the lithium-containing phosphate particle materials described above can be mixed according to actual needs by those skilled in the art.

[0126] The present application improves the fast charging capability of the battery cell by using a small particle size negative electrode active material, which is beneficial to improve the transmission path of lithium ions in the negative electrode active material during charging. However, when the fast charging capability of the battery cell is improved, the corresponding charging current it can withstand is also improved. At this time, if the positive electrode active material is not reasonably arranged, it will cause the internal heat of the battery cell to gather during fast charging, the internal temperature of the battery will rise, and adverse reactions such as electrolyte gas production and increase of the solid electrolyte interface film impedance of the negative electrode will occur, thereby increasing the internal resistance of the battery and affecting the cycle performance of the battery cell. The present application reasonably selects different sizes of lithium-containing phosphates as positive electrode active materials, effectively reduces the heat gathering in the battery cell by mixing large and small particles, reduces the internal temperature rise of the battery cell, and inhibits the growth of the direct current resistance of the battery cell. At the same time, the energy density of the battery cell is also improved.

[0127] [Positive electrode sheet]

[0128] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. As an example, the positive electrode current collector has two surfaces opposite in the thickness direction of itself, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0129] In some embodiments, the positive electrode film layer includes a positive electrode active material.

[0130] In some embodiments, the positive electrode active material includes an olivine-structured lithium-containing phosphate.

[0131] In some embodiments, the olivine-structured lithium-containing phosphate has a general formula as shown in Formula I,

[0132] Li x A y Me a M b P 1-c X c Yz Formula I,

[0133] wherein 0.1≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A comprises one or more of Na, K, Mg; Me comprises one or more of Mn, Fe, Co, Ni; M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X comprises one or more of S, Si, Cl, B, C, N; Y comprises one or more of O, F.

[0134] As used herein, "the lithium-containing phosphate composition of olivine structure has a general formula as shown in Formula I" is not only limited to the substance represented by the molecular formula, but also includes other substances formed by further modifying the substance on the basis of the molecular formula, which is not limited herein. The use of "general formula" is only for the convenience of description, and is not intended to limit the present application. It can be understood that the material obtained by appropriately modifying the listed positive electrode active material is also within the scope of the positive electrode active material, and the aforementioned appropriate modification refers to acceptable modification of the positive electrode active material, and non-limiting examples include coating modification.

[0135] When the lithium-containing phosphate as the positive electrode active material has the above chemical formula, the structural stability of the positive electrode active material can be further improved, and the cycle performance of the battery cell can be improved.

[0136] In some embodiments, M comprises one or more of Al, Ti, V, Mg.

[0137] In some embodiments, the positive electrode active material contains Al element, and the mass content of the Al element is 0.001% to 0.05%, which can be optionally 0.01% to 0.05%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, or other unlisted values within the range of 0.001% to 0.05%.

[0138] In some embodiments, the positive electrode active material contains Ti element, and the mass content of the Ti element is 0.001% to 0.03%, which can be optionally 0.01% to 0.03%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.02%, 0.03%, or other unlisted values within the range of 0.001% to 0.03%.

[0139] In some embodiments, the positive electrode active material contains V element, the mass content of which is 0.001% to 0.3%, optionally 0.1% to 0.3%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, or other values not listed in the range of 0.001% to 0.3%.

[0140] In some embodiments, the positive electrode active material contains Mg element, the mass content of which is 0.001% to 0.01%, based on the total mass of the positive electrode active material, optionally 0.001%, 0.002%, 0.005%, 0.01%, or other values not listed in the range of 0.001% to 0.01%.

[0141] When the lithium-containing phosphate contained in the positive electrode active material contains Al, Ti, V, Mg, etc., the structural stability of the material can be further improved, and the cycle performance can be improved.

[0142] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the olivine-structured lithium-containing phosphate contains first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm.

[0143] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the olivine-structured lithium-containing phosphate contains first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm, such as 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, or other values not listed in the range of 0.05 μm to 0.3 μm.

[0144] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the olivine-structured lithium-containing phosphate contains second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, or other values not listed in the range of 1 μm to 3 μm.

[0145] In the battery cell provided in 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, the direct current internal resistance of the battery cell can be further improved, thereby further reducing the heat generation of the battery, and the battery has excellent safety performance.

[0146] The battery cell provided in the present application contains first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1-3 μm as the positive electrode active material. The size grading of the particles can effectively improve the compaction density of the electrode sheet, and thus the battery cell has a high energy density.

[0147] In some embodiments, 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.

[0148] When the number of the first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 μm is greater than the number of the second lithium-containing phosphate particles with a longest diameter of 1-3 μm as the positive electrode active material, the direct current internal resistance and the fast charging performance of the battery can be further improved.

[0149] In some embodiments, the positive electrode film layer optionally further comprises a positive electrode conductive agent. The present application does not have a particular limitation on the type of the positive electrode conductive agent. As an example, the positive electrode conductive agent comprises at least one of super conductive carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0150] In some embodiments, the positive electrode film layer optionally further comprises a positive electrode binder. The present application does not have a particular limitation on the type of the positive electrode binder. As an example, the positive electrode binder can comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylic ester resin.

[0151] In some embodiments, the areal density of the positive electrode film layer on one side is 0.33-0.4 g / 15 40.25 mm 2 , for example, 0.33 g / 15 40.25 mm 2 , 0.34 g / 15 40.25 mm 2 , 0.35 g / 15 40.25 mm 2 , 0.36 g / 15 40.25 mm 2 , 0.37 g / 15 40.25 mm 2 , 0.38 g / 15 40.25 mm 2 , 0.39 g / 15 40.25 mm 2 , or 0.4 g / 15 40.25 mm 2 . 2 2 ​0.4 g / 15 40.25 mm 2 other unlisted values within the ranges.

[0152] In some embodiments, the areal density of a single side of the positive electrode film layer is 0.335 g / 15 40.25 mm 2 0.38 g / 15 40.25 mm 2 .

[0153] As used herein, the "areal density" of a positive electrode film layer or a negative electrode film layer has the meaning known in the art and can be tested using methods known in the art. For example, a single-side coated and cold-pressed negative electrode sheet (if a double-side coated negative electrode sheet, the negative electrode film layer of one side can be wiped off first) is punched into a small round piece with an area of S1, weighed, and recorded as M1. Then the negative electrode film layer of the weighed negative electrode sheet is wiped off, the weight of the negative electrode current collector is weighed and recorded as M0, and the areal density of the negative electrode film layer = (weight of the negative electrode sheet M1 - weight of the negative electrode current collector M0) / S1. To ensure the accuracy of the test results, multiple groups (e.g., 10 groups) of samples to be tested can be tested, and the average value is calculated as the test result.

[0154] The battery cell provided in the present application can further improve the energy density of the battery and avoid the influence of thick coating on the electrochemical performance when the coating areal density of the positive electrode film layer is within the above range, thereby further improving the fast-charging performance of the battery.

[0155] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. As an example of a metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one side surface of the polymer material base layer. As an example, the metal material can include at least one of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0156] 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, or other unlisted values within the range of 10 μm to 15 μm.

[0157] In some embodiments, the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 5 to 12, such as 5, 6, 7, 8, 9, 10, 11, 12, or other unlisted values within the range of 5 to 12.

[0158] In some embodiments, the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 6 to 10.

[0159] In the battery provided by the present application, when the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is within the above range, the thickness of the current collector is within a suitable range, so that the problem of the positive electrode sheet cracking caused by poor flow capacity and low tensile strength due to excessive thickness or too thin thickness is avoided, and the energy density and fast charging performance of the battery are further improved.

[0160] In some embodiments, as shown in FIG. 5, the current collector 11 includes a current collecting portion 11a and at least two tabs 11b disposed on the same side of the current collecting portion 11a and extending from the current collecting portion 11a along a first direction F1, wherein the distance between the center lines L of two adjacent tabs 11b is 10 mm to 350 mm, the center 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, or other values not listed in the range of 10 mm to 350 mm.

[0161] 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, or other values not listed in the range of 20 mm to 330 mm.

[0162] In some embodiments, as shown in FIGS. 5 and 6, the current collector 11 can be a positive electrode current collector, and the tab 11b can be a positive electrode tab 111b.

[0163] In some embodiments, as shown in FIGS. 5 and 6, the current collector 11 can be a negative electrode current collector, and the tab 11b can be a negative electrode tab 112b.

[0164] In some embodiments, the positive current collector comprises a positive current collecting portion and at least two positive tabs disposed on the same side of the positive current collecting portion, the positive tabs extending from the positive current collecting portion along a first direction, wherein the distance between the center lines of two adjacent positive tabs is 10 mm to 350 mm, the center lines being parallel to the first direction, for example, 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 350 mm, or other values not listed in the range of 10 mm to 350 mm.

[0165] In some embodiments, the distance between the center lines of two adjacent positive 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, or other values not listed in the range of 20 mm to 330 mm.

[0166] In some embodiments, as shown in FIG. 5, the center line L refers to the axis of symmetry passing through the midpoint of the tab 11b along the length direction of the current collector 11, and the center line L is parallel to the first direction F1. In some embodiments, the size of each tab 11b along the length direction of the current collector 11 is equal.

[0167] In some embodiments, as shown in FIG. 5, the distance between the center lines L of two adjacent tabs 11b comprises S1 or S2, wherein S1 and S2 can be equal (in which case the adjacent tabs are equally spaced), or S1 and S2 can not be equal (in which case the adjacent tabs are not equally spaced).

[0168] The battery cell provided in the present application can further improve the overcurrent capacity and the direct current resistance of the battery cell when the positive and negative current collectors comprise at least two tabs with the above structural characteristics, thereby further reducing the heat generation of the battery and improving the safety performance of the battery.

[0169] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (for example, N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive current collector, and after drying, cold pressing, and other processes, the positive electrode tab can be obtained.

[0170] In some embodiments, the compacted density of the positive electrode tab is 2.3 g / cm 3 to 2.6 g / cm 3 , for example 2.30 g / cm 3 , 2.35 g / cm 3 , 2.40 g / cm 3 , 2.45 g / cm 3 , 2.50 g / cm 3 , 2.55 g / cm 3 , 2.60 g / cm 3 , or other unlisted values within the range of 2.3 g / cm 3 to 2.6 g / cm 3 .

[0171] In some embodiments, the compacted density of the positive electrode tab is 2.4 g / cm 3 to 2.55 g / cm 3 .

[0172] When the compacted density of the positive electrode tab is within the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0173] In some embodiments, the compacted density of the positive electrode tab corresponds to the compacted density of the positive electrode film layer of a battery cell in a 0% SOC state, wherein the battery cell in the 0% SOC state is discharged at 1 / 3C to 2.0V, and then discharged at 0.05C to 2.0V.

[0174] [Negative electrode tab]

[0175] In some embodiments, the negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector. As an example, the negative electrode current collector has two opposite surfaces in the thickness direction of itself, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0176] In some embodiments, the negative electrode film layer includes a negative electrode active material.

[0177] In some embodiments, the average particle size Dv50 of the negative electrode active material is 8 pm to 15 pm, for example 8 pm, 9 pm, 10 pm, 11 pm, 12 pm, 13 pm, 14 pm, 15 pm, or other unlisted values within the range of 8 pm to 15 pm. In some embodiments, the negative electrode active material includes graphite.

[0178] In the battery monomer provided in the present application, when the particle size of the negative electrode active material (for example, graphite) is in the above range, the specific surface area is large, the migration channel of lithium ions between the graphite layers is increased, the migration path is shortened, thereby accelerating the embedding and stripping speed of lithium ions between the graphite layers, so that the battery monomer has good fast charging performance; at the same time, when the particle size of the negative electrode active material (for example, graphite) is in the above range, the direct current internal resistance of the battery monomer can also be improved, thereby reducing the heat generation of the battery, so that the battery has good safety performance.

[0179] In some embodiments, the average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm, for example, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, or other unlisted values within the range of 9.5 μm to 11.5 μm.

[0180] When the particle size of the negative electrode active material (for example, graphite) is in the above range, the fast charging performance and the direct current internal resistance of the battery can be further improved, and at the same time, the battery has good cycle performance.

[0181] In some embodiments, the specific surface area of the negative electrode active material is 3 m 2 / g to 8 m 2 / g, for example, 3 m 2 / g, 4 m 2 / g, 5 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, etc., or other unlisted values within the range of 3 m 2 / g to 8 m 2 / g.

[0182] In some embodiments, the specific surface area of the negative electrode active material is 4 m 2 / g to 6 m 2 / g, for example, 4 m 2 / g, 4.5 m 2 / g, 5 m 2 / g, 5.5 m 2 / g, 6 m 2 / g, etc., or other unlisted values within the range of 4 m 2 / g to 6 m 2 / g.

[0183] As used herein, "specific surface area" refers to the total area possessed by a unit mass of material. The determination method can refer to GB / T 19587-2017, and is tested by a nitrogen adsorption specific surface area analysis test, and is calculated by a BET (Brunauer Emmett Teller) method. The nitrogen adsorption specific surface area analysis test can be performed by a Tri-Star 3020 specific surface area pore size analyzer of the United States Micromeritics company.

[0184] When the negative active material (for example, graphite) has a specific surface area in the above range, the speed of lithium ion intercalation and deintercalation between graphite layers can be further accelerated, thereby further improving the fast charging performance of the battery.

[0185] In some embodiments, the negative electrode film layer includes at least two negative active material layers. In some embodiments, the negative electrode film layer includes a first negative active material layer disposed on the surface of the negative electrode current collector and a second negative active material layer disposed on the side of the first negative active material layer away from the negative electrode current collector, the negative active material in the first negative active material layer includes a first artificial graphite, and the negative active material in the second negative active material layer includes a 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. The particle size of the artificial graphite in the upper negative electrode film layer (the second negative active material layer) is small. The upper graphite is in direct contact with the electrolyte and can respond more quickly to the intercalation of lithium ions than the lower graphite. Therefore, the upper graphite has a small particle size, which helps lithium ions to intercalate more quickly and improves the fast charging capacity of the battery. At the same time, the use of larger artificial graphite particles in the lower layer can reduce the probability of crushing the graphite material and improve the compaction density of the electrode sheet.

[0186] In some embodiments, the average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm, for example, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or other unlisted values within the range of 11 μm to 15 μm.

[0187] In some embodiments, the average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm, for example, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or other unlisted values within the range of 8 μm to 15 μm.

[0188] In some embodiments, the average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm, for example, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, or other unlisted values within the range of 9.5 μm to 11.5 μm.

[0189] The battery cell provided by the present application can further improve the kinetic performance of the battery when the double-layer coating scheme is used in the negative electrode film layer.

[0190] In some embodiments, the negative electrode film layer can optionally further comprise a binder. The binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0191] In some embodiments, the negative electrode film layer can optionally further comprise a conductive agent. The conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0192] In some embodiments, the negative electrode film layer can optionally further comprise other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0193] In some embodiments, the areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 , for example, 0.15 g / 15 40.25 mm 2 , 0.16 g / 15 40.25 mm 2 , 0.17 g / 15 40.25 mm 2 , 0.18 g / 15 40.25 mm 2 , 0.19 g / 15 40.25 mm 2 , or other unlisted values within the range of 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 .

[0194] In some embodiments, the areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.165 g / 15 40.25 mm 2 .

[0195] The battery cell provided by the present application can further improve the energy density of the battery when the coating areal density of the negative electrode film layer is within the above range, and can also avoid the influence of thick coating on the electrochemical performance, thereby further improving the fast-charging performance of the battery.

[0196] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (e.g., a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0197] In some embodiments, the thickness of the negative current collector is 4 μm to 6 μm, for example, 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.

[0198] In some embodiments, the ratio of the single-side thickness of the negative film layer to the thickness of the negative current collector is 12 to 20, for example, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc., or other unlisted values within the range of 12 to 20.

[0199] In some embodiments, the ratio of the single-side thickness of the negative film layer to the thickness of the negative current collector is 13 to 20.

[0200] In some embodiments, the single-side thickness of the negative film layer corresponds to the single-side thickness of the negative film layer of a battery cell in a 0% SOC state, where the battery cell in the 0% SOC state is discharged at 1 / 3 C to 2.0 V and then discharged at 0.05 C to 2.0 V. When the ratio of the single-side thickness of the negative film layer to the thickness of the negative current collector is within the above range, the battery provided herein can further improve the energy density and fast-charging performance of the battery.

[0201] In some embodiments, the negative current collector includes a negative current collecting portion and at least two negative tabs disposed on the same side of the negative current collecting portion, and the negative tabs extend from the negative current collecting portion along a first direction, wherein the distance between the center lines of two adjacent negative tabs is 10 mm to 350 mm, and the center lines are 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.

[0202] In some embodiments, the distance between the center lines of two adjacent negative tabs is 20-330 mm, for example, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 330 mm, or other values not listed in the range of 20-330 mm.

[0203] The battery cell provided in the present application can further improve the overcurrent capacity, improve the direct current resistance of the battery cell, thereby further reducing the heat generation of the battery, and make the battery have better safety performance when the positive and negative current collectors include at least two tabs with the above structural characteristics.

[0204] In some embodiments, the size of the positive film layer along the first direction is W1 mm, and the size of the negative film layer along the first direction is W2 mm, wherein W2>W1, and the difference between W2 and W1 is 3-5 mm, for example, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5 mm, or other values not listed in the range of 3-5 mm.

[0205] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be made into an electrode assembly through a rolling process or a stacking process.

[0206] In some embodiments, the battery cell is a rolling battery. As shown in FIG. 3, after the electrode sheet is unfolded from the rolling state, the positive current collector includes a positive current collecting part 111a and at least two positive tabs 111b disposed on the same side of the positive current collecting part 111a, the positive tabs 111b extending from the positive current collecting part 111a along the first direction F1; the negative current collector includes a negative current collecting part 112a and at least two negative tabs 112b disposed on the same side of the negative current collecting part 112a, the negative tabs 112b extending from the negative current collecting part 112a along the first direction F1. The size of the negative film layer along the first direction W2 is greater than the size of the positive film layer along the first direction W1, and the difference is 3-5 mm.

[0207] In some embodiments, the battery cell is a stacked battery. Referring to Figures 1 and 2, each electrode sheet is stacked to form an electrode assembly. Each positive electrode sheet includes a positive current collector, which includes a positive current collector portion 111a and a positive electrode tab 111b disposed on the positive current collector portion 111a. The positive electrode tab 111b extends from the positive current collector portion 111a along a first direction F1. Each negative electrode sheet includes a negative current collector, which includes a negative current collector portion 112a and a negative electrode tab 112b disposed on the negative current collector portion 112a. The negative electrode tab 112b extends from the negative current collector portion 112a along the first direction F1. The dimension W2 of the negative electrode film layer along the first direction is greater than the dimension W1 of the positive electrode film layer along the first direction, with a difference of 3 mm to 5 mm.

[0208] During battery cycling, lithium ions that cannot be embedded in the negative electrode in time may form lithium dendrites on the negative electrode surface, deteriorating the battery's cycle performance. In the battery cell provided in this application, when the size W2 of the negative electrode film layer and the size W1 of the positive electrode film layer have the above-mentioned relationship, the formation of lithium dendrites on the negative electrode surface can be improved, thereby enabling the battery to have good cycle performance at the same time.

[0209] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0210] In some embodiments, the compaction density of the negative electrode sheet is 1.3 g / cm³. 3 Up to 1.6 g / cm 3 For example, 1.3g / cm 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm 3 Wait, or 1.3g / cm 3 Up to 1.6 g / cm 3 Other values ​​not listed within the range.

[0211] In some embodiments, the compaction density of the negative electrode sheet is 1.35 g / cm³. 3 Up to 1.55 g / cm 3 For example, 1.35g / cm 3 1.40g / cm 3 1.45g / cm 3 1.50g / cm 3 1.55g / cm3 or 1.35 g / cm3 3 to 1.55 g / cm3 3 other values not listed in the range.

[0212] In some embodiments, the compaction density of the negative electrode tab corresponds to the compaction density of the negative electrode film layer corresponding to the battery cell in the 0% SOC state, wherein the battery cell in the 0% SOC state refers to a battery cell discharged at 1 / 3C to 2.0V and then discharged at 0.05C to 2.0V.

[0213] As used herein, the "compaction density" of the tab is: compaction density = areal density / (tab thickness - current collector thickness), which can be determined according to GB / T 24533-2009.

[0214] When the compaction density of the negative electrode tab is in the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0215] [Electrolyte]

[0216] The electrolyte serves to conduct ions between the positive electrode tab and the negative electrode tab. For example, the electrolyte can be liquid, solid or gel.

[0217] In some embodiments, the electrolyte uses an electrolyte solution. The electrolyte solution includes an electrolyte salt and an organic solvent.

[0218] In the embodiments of the present application, the types and contents of the organic components in the electrolyte solution are of the meanings known in the art, and can be detected using devices and methods known in the art, for example, the composition of the electrolyte solution can be detected by liquid chromatography, gas chromatography, ion chromatography, liquid nuclear magnetic resonance, etc. For example, the organic components in the electrolyte solution can be qualitatively and quantitatively analyzed by gas chromatography according to GB / T 9722-2006 "General Gas Chromatography for Chemical Reagents".

[0219] The test sample in the embodiments of the present application can be a freshly prepared electrolyte solution, or free electrolyte solution obtained from a battery discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC.

[0220] In the embodiments of the present application, the type and content of the inorganic component / lithium salt concentration in the electrolyte are the meanings known in the art, which can be detected by using the devices and methods known in the art, for example, the qualitative or quantitative analysis of the inorganic component / lithium salt concentration in the electrolyte can be performed by ion chromatography according to the standard JY / T020-1996 "General Ion Chromatography Analysis Method". In the embodiments of the present application, the freshly prepared electrolyte can be taken as a sample, or the free electrolyte obtained from the battery after the battery is discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC), and the ion chromatography analysis method is used for detection.

[0221] In some embodiments, the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

[0222] 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.

[0223] In some embodiments, the organic solvent includes a linear carboxylic acid ester, and the mass fraction of the linear carboxylic acid ester based on the total mass of the electrolyte is 40% to 75%, for example, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or other values not listed in the range of 40% to 75%.

[0224] In some embodiments, the linear carboxylic acid ester has a general structural formula of R1-COO-R2, wherein R1 and R2 each independently includes one or more of C1-C5 alkyl and C1-C5 halogenated alkyl.

[0225] In some embodiments, the linear carboxylic acid ester includes one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

[0226] When the above type and mass fraction of the linear carboxylic acid ester is used as the organic solvent in the electrolyte, the linear carboxylic acid ester can effectively improve the electrolyte conductivity due to its low viscosity, thereby further improving the fast-charging performance of the battery.

[0227] In some embodiments, the organic solvent includes a carbonate solvent, and the carbonate solvent includes a linear carbonate and a cyclic carbonate, and the mass fraction of the linear carbonate based on the total mass of the electrolyte is 10% to 40%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or other values not listed in the range of 10% to 40%.

[0228] In some embodiments, the cyclic carbonate includes one or more of ethylene carbonate, propylene carbonate, and the linear carbonate includes one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0229] In some embodiments, the linear carbonate includes dimethyl carbonate, and the mass percentage of the dimethyl carbonate is 5% to 15%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or the like, or other unlisted values within the range of 5% to 15%, based on the total mass of the electrolyte.

[0230] When the above type and mass percentage of carbonate is used as the organic solvent in the electrolyte, the side reactions and the degree of gas generation of the battery during the cycle process can be improved, so that the battery has good cycle performance.

[0231] In some embodiments, the organic solvent 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, for example, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, or the like, or other unlisted values within the range of 2.0 to 7.0.

[0232] In some embodiments, the organic solvent includes dimethyl carbonate and linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.0.

[0233] When the above mass ratio of dimethyl carbonate and linear carboxylic acid ester is used as the organic solvent in the electrolyte, the fast-charging performance and the cycle performance of the battery can be further improved by the combination of the two solvents.

[0234] In some embodiments, the electrolyte further includes a lithium salt, for example, at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethylsulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalate borate, lithium di oxalate borate, lithium difluoro di-oxalate phosphate, and lithium tetrafluoro oxalate phosphate.

[0235] In some embodiments, the mass percentage of the lithium salt is 13% to 20%, for example, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or the like, or other unlisted values within the range of 13% to 20%, based on the total mass of the electrolyte.

[0236] In some embodiments, the lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and fluorine-containing sulfonimide salt, and the fluorine-containing sulfonimide salt includes one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis-trifluoromethylsulfonylimide LiTFSI.

[0237] The dissociation ability of the fluorine-containing sulfimide salt is strong, and the use of lithium hexafluorophosphate in combination can further improve the fast charging performance of the battery, but excessive content of LiTFSI will reduce the safety performance of the battery, especially make the battery heat runaway more intense.

[0238] In some embodiments, the lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfimide LiFSI.

[0239] In some embodiments, in the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfimide LiFSI is 1.2:1 to 2:1, for example, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, or other values not listed in the range of 1.2:1 to 2:1.

[0240] When lithium hexafluorophosphate and lithium bisfluorosulfimide in the above mass ratio range are used in the electrolyte at the same time, the fast charging performance and cycle performance of the battery can be further improved.

[0241] In some embodiments, the electrolyte further includes an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain performance of the battery, for example, an additive capable of improving the overcharge performance of the battery, an additive capable of improving the high-temperature or low-temperature performance of the battery, etc.

[0242] In some embodiments, the electrolyte includes a carbonate additive, and the carbonate additive includes fluoroethylene carbonate FEC and vinylene carbonate VC.

[0243] In some embodiments, the mass fraction of the carbonate additive is 0.5% to 7% based on the total mass of the electrolyte, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 6.5%, 7%, or other values not listed in the range of 0.5% to 7%.

[0244] In the battery cell provided in the present application, the carbonate additive, for example, fluoroethylene carbonate and vinylene carbonate, with a mass fraction in the above range, is also added to the electrolyte, which can form an SEI film on the negative electrode surface, thereby reducing the side reactions between the electrode and the electrolyte, and further making the battery have better cycle performance.

[0245] In some embodiments, the electrolyte comprises vinylene carbonate VC, and the mass percentage of the vinylene carbonate VC in the electrolyte is 0.5% to 2%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or the like, or other values not listed in the range of 0.5% to 2%.

[0246] When the electrolyte is added with the vinylene carbonate in the above mass percentage range as an additive, the SEI film formed is more stable, which is conducive to further improving the cycle performance of the battery.

[0247] In some embodiments, the electrolyte comprises fluoroethylene carbonate FEC, and the mass percentage of the fluoroethylene carbonate FEC in the electrolyte is 0.1% to 1%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or the like, or other values not listed in the range of 0.1% to 1%.

[0248] When the electrolyte is added with the fluoroethylene carbonate in the above mass percentage range as an additive, the SEI film formed has low impedance, which can further improve the fast-charging performance of the battery.

[0249] In some embodiments, the types and mass of the additives and solvents in the electrolyte can be obtained by detecting the electrolyte by methods known to those skilled in the art. For example, the composition in the electrolyte can be measured by liquid chromatography, gas chromatography, ion chromatography, liquid nuclear magnetic resonance, and the like. Illustratively, the electrolyte is diluted to 3-10 times with acetonitrile to obtain an electrolyte diluent to be tested, and the electrolyte diluent is placed in a GC-MS 3100 organic component gas chromatograph for full-scan qualitative analysis. The injection port temperature is 250°C, and the scanning range is 35 μm-270 μm. After the test is completed, the total ion current chromatogram of each organic matter is obtained. According to the peak position of the chromatogram, the corresponding organic matter type is compared, and the percentage content of each organic matter is calculated according to the peak area.

[0250] The qualitative and quantitative detection of each substance or element in the present application can be carried out by using suitable equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, and the like. Those skilled in the art can also adaptively change certain detection steps / instrument parameters from the perspective of detection accuracy, so as to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used jointly for qualitative or quantitative determination.

[0251] In the embodiments of the present application, the type and content of the inorganic component / lithium salt concentration in the electrolyte solution are in the meaning known in the art, and can be detected by using the devices and methods known in the art, such as gas chromatography, liquid chromatography, liquid nuclear magnetic method, etc.

[0252] In the embodiments of the present application, the freshly prepared electrolyte solution can be taken as a sample, or the battery that has been discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC) can be disassembled in reverse.

[0253] [Separator]

[0254] In some embodiments, the battery cell further comprises a separator. The type of the separator is not particularly limited in the present application, and any known porous structure separator with good chemical stability and mechanical stability can be selected.

[0255] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0256] [Battery cell]

[0257] In some embodiments, the positive electrode sheet, the negative electrode sheet and the separator can be made into an electrode assembly by a winding process or a stacking process.

[0258] In some embodiments, the positive current collector, the separator, the negative current collector and the separator are sequentially stacked and wound together; after winding, the positive electrode tabs 111b of the positive current collector are aligned and stacked, and the negative electrode tabs 112b of the negative current collector are aligned and stacked, as shown in FIG. 6.

[0259] In some embodiments, the battery cell further comprises a top cover, and the top cover comprises electrode terminals with opposite polarities for electrically connecting with the positive electrode tabs or the negative electrode tabs.

[0260] In some embodiments, as shown in FIG. 6, the battery cell 10 further comprises a top cover 13, and the top cover 13 comprises two electrode terminals 131 with opposite polarities, one of which is a positive electrode terminal 131 for electrically connecting with the positive electrode tabs 111b, and the other is a negative electrode terminal 131 for electrically connecting with the negative electrode tabs 112b.

[0261] The positive tab 111b after winding is aligned and in a stacked manner, has a larger connection area, so as to facilitate the direct electrical connection of the positive tab 111b with the electrode terminal 131, without the need to connect the positive tab 111b with the electrode terminal 131 through the adapter piece. Similarly, the negative tab 112b after winding is aligned and in a stacked manner, has a larger connection area, so as to facilitate the direct electrical connection of the negative tab 112b with the electrode terminal 131, without the need to connect the negative tab 112b with the electrode terminal 131 through the adapter piece.

[0262] In a conventional battery, an adapter piece is needed to connect the electrode terminal with the tab, but the utilization rate of the electrode assembly is thus lost, and the energy density of the battery is reduced. In the battery cell provided in the present application, the use of the above structure can effectively solve this problem, reduce the internal resistance of the battery, and further improve the energy density and fast charging performance of the battery.

[0263] In some embodiments, the battery cell can include an outer package. The outer package can be used to package the above-mentioned electrode assembly and electrolyte.

[0264] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate, etc. can be listed.

[0265] In some embodiments, as shown in FIGS. 6-9, the battery cell 10 further includes a housing 14, and the current collector 11 is disposed in the housing 14.

[0266] In some embodiments, as shown in FIGS. 6-9, the housing 14 is square, the thickness T of the housing is 30-55 mm, the width W of the housing is 150-250 mm, and the height H of the housing is 90-120 mm.

[0267] In some embodiments, the thickness T of the housing is 30-55 mm, such as 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, etc., or other unlisted values within the range of 30-55 mm.

[0268] In some embodiments, the width W of the housing is 150-250 mm, such as 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, etc., or other unlisted values within the range of 150-250 mm.

[0269] In some embodiments, the height H of the shell is 90 mm to 120 mm, for example 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, or other unlisted values within the range of 90 mm to 120 mm.

[0270] In some embodiments, the battery cell is configured to have a charging time of 10 min to 17 min from 10% SOC to 80% SOC at room temperature, for example 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, or other unlisted values within the range of 10 min to 17 min.

[0271] The battery cell provided in the present application has excellent fast charging performance.

[0272] In some embodiments, the shape of the battery cell is not particularly limited in the present application, which can be cylindrical, square or any other shape. For example, FIG. 10 is a battery cell 5 in a square structure as an example. Optionally, the battery cell is a lithium ion battery or a sodium ion battery.

[0273] In some embodiments, referring to FIG. 11, the outer package can include a shell 51 and a cover plate 53. The shell 51 can include a bottom plate and a side plate connected to the bottom plate, which enclose a receiving cavity. The shell 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the separator film can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific actual needs.

[0274] In some embodiments, a battery device is provided, which can be a battery module, a battery pack, an energy storage battery, etc. The above-mentioned battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0275] FIG. 12 is a battery module 4 as an example. Referring to FIG. 12, 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, other arbitrary arrangements can also be used. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0276] Optionally, the battery module 4 can further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0277] In some embodiments, the battery module described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0278] FIGS. 13 and 14 are a battery pack 1 as an example. Referring to FIGS. 13 and 14, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box 2 and a lower box 3, and the upper box 2 can be arranged on the lower box 3 to form an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0279] [Power-Consuming Device]

[0280] In addition, the present application also provides a power-consuming device, which includes at least one of the battery cell, the battery module, or the battery pack provided by the present application. The battery cell, the battery module, or the battery pack can be used as a power source of the power-consuming device, or can be used as an energy storage unit of the power-consuming device. The power-consuming device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0281] As the power-consuming device, the battery cell, the battery module, or the battery pack can be selected according to the use requirements thereof.

[0282] FIG. 15 is a power-consuming device as an example. The power-consuming device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of high power and high energy density of the battery cell for the power-consuming device, the battery pack or the battery module can be used.

[0283] In some embodiments, the power-consuming device includes a vehicle, and the length direction of the electrode assembly is arranged along the traveling direction of the vehicle.

[0284] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and the battery cell can be used as a power source.

[0285] Embodiments

[0286] Hereinafter, the examples of the present application will be described. The examples described below are illustrative and are intended to be purely exemplary of the application and are not intended to limit the present application. Unless otherwise indicated, technical or conditions not specified in the examples are performed according to the techniques or conditions described in the literature in the art or according to the product manual. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained on the market.

[0287] Example 1

[0288] 1) Negative electrode tab

[0289] The negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene butadiene rubber, and the thickening agent sodium carboxymethyl cellulose were mixed in a mass ratio of 96:1:2:1, and then a solvent deionized water was added to stir into a negative electrode slurry. The negative electrode slurry was uniformly coated on a negative electrode current collector copper foil, and after drying and cold pressing, a negative electrode tab was obtained; wherein the thickness of the negative electrode current collector copper foil was 4.5 μm, the single-sided area density of the negative electrode tab was 0.155 g / 1540.25 mm 2 , and the size of the negative electrode film layer along the first direction was 92 mm; the volume particle size Dv50 of the artificial graphite was 11 μm, and the specific surface area was 5.5 m 2 / g.

[0290] 2) Positive electrode tab

[0291] The positive electrode active material lithium iron phosphate (LFP), the binder polyvinylidene fluoride, and the conductive agent acetylene black were mixed in a mass ratio of 97:2:1, and then a solvent N-methyl pyrrolidone (NMP) was added to stir into a positive electrode slurry; the positive electrode slurry was uniformly coated on a positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode tab was obtained. The thickness of the positive electrode current collector aluminum foil was 13 μm, the single-sided area density of the positive electrode tab was 0.341 g / 1540.25 mm 2 , and the size of the positive electrode film layer along the first direction was 88.5 mm; the positive electrode active material contained 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, and in the longitudinal cross section of the positive electrode tab, any region containing at least 100 olivine structure lithium-containing phosphates was selected, and in the region, the number of the first lithium-containing phosphate particles was greater than the number of the second lithium-containing phosphate particles.

[0292] 3) Electrolyte

[0293] Dimethyl carbonate (DMC), ethyl acetate (EA), ethylene carbonate (EC), methyl ethyl carbonate (EMC) were uniformly mixed in a mass ratio of 10:50:35:5 to obtain an electrolyte solvent. Lithium hexafluorophosphate (LiPF6) and lithium bisfluorosulfonylimide (LiFSI) were included as lithium salts, and were fully stirred until they were completely dissolved. Additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) were included in a mass percentage of 0.7% and 0.3% respectively with respect to the total mass of the electrolyte. The mass percentage of lithium hexafluorophosphate (LiPF6) was 8.9% and the mass percentage of lithium bisfluorosulfonylimide LiFSI was 4.6% based on the total mass of the electrolyte. The lithium ion conductivity of the electrolyte was 14.5 mS / cm.

[0294] 4) Separator

[0295] A commercially available polyethylene microporous film with a thickness of 7 μm and an average pore size of 80 nm was used as the separator.

[0296] 5) Battery cell

[0297] The positive electrode sheet and the negative electrode sheet were cut to have tabs, the distance between the center lines of the two adjacent tabs of the positive electrode sheet was 316 mm, and the distance between the center lines of the two adjacent tabs of the negative electrode sheet was 314 mm. The positive electrode sheet, the separator, and the negative electrode sheet were stacked in order and wound to obtain a wound electrode assembly, so that each layer of the electrode assembly had at least one tab. The electrode assembly was placed in an outer packaging square aluminum shell with a thickness of 50 mm, a width of 208 mm, and a height of 103 mm, and after drying, the electrolyte was injected. After packaging, standing, formation, aging, secondary packaging, and capacity processes, a battery cell was obtained, and the tabs of the battery cell were connected to the cover plate.

[0298] Examples 2-5

[0299] The battery cells of Examples 2-5 were basically similar to Example 1, except that the particle size Dv50 of the graphite was adjusted, as shown in Tables 1-4.

[0300] Example 6

[0301] The battery cell of Example 6 was basically similar to Example 1, except that the proportion of large and small particles of LFP in the positive electrode active material was changed, so that in the longitudinal cross-section of the positive electrode sheet, any region containing at least 100 olivine structure-containing lithium-containing phosphates was selected, and in the any region, the number of first lithium-containing phosphate particles (with a longest diameter of 0.3-1 μm) was less than the number of second lithium-containing phosphate particles (with a longest diameter of 3-5 μm), as shown in Tables 1-4.

[0302] Examples 7-10

[0303] The battery cells of Examples 7-10 are substantially similar to Example 1, except that the types or contents of the organic solvents and lithium salts in the electrolyte are changed, as shown in Tables 1-4.

[0304] Example 11

[0305] The battery cell of Example 11 is substantially similar to Example 1, except that the negative active material is coated in two layers, as follows: a particle size Dv50 of 13 pm artificial graphite is used as the lower layer, and a particle size Dv50 of 10 pm artificial graphite is used as the upper layer, which are uniformly coated on the negative current collector copper foil, dried, and cold-pressed to obtain a negative electrode sheet. Details are shown in Tables 1-4.

[0306] Examples 12-13

[0307] The battery cells of Examples 12-13 are substantially similar to Example 1, except that the thickness ratio of the single-sided film layer to the current collector of the positive and negative electrodes is changed, as shown in Tables 1-4.

[0308] Comparative Examples 1-2

[0309] Comparative Examples 1-2 are substantially similar to Example 1, except that the particle size Dv50 and specific surface area of the graphite are adjusted, as shown in Tables 1-4.

[0310] Comparative Example 3

[0311] Comparative Example 3 is substantially similar to Example 1, except that the size particle ratio of LFP in the positive active material is changed, so that in the longitudinal section of the positive electrode sheet, any region containing at least 100 olivine-structured lithium-containing phosphates is selected, in which there are second lithium-containing phosphate particles with a longest diameter of 3-5 pm, and there are no first lithium-containing phosphate particles with a longest diameter of 0.3-1 pm. Details are shown in Tables 1-4.

[0312] Comparative Example 4

[0313] Comparative Example 4 is substantially similar to Example 1, except that the size particle ratio of LFP in the positive active material is changed, so that in the longitudinal section of the positive electrode sheet, any region containing at least 100 olivine-structured lithium-containing phosphates is selected, in which there are first lithium-containing phosphate particles with a longest diameter of 0.3-1 pm, and there are no second lithium-containing phosphate particles with a longest diameter of 3-5 pm. Details are shown in Tables 1-4.

[0314] I. Performance Test

[0315] 1. DC Internal Resistance

[0316] The direct current internal resistance (DCR) test of the battery cell can refer to the method in GB / T31467 "HEV high-power lithium-ion power battery performance test specification". For example, at room temperature, the battery cell is charged to 3.65V at a constant current of 0.33C, stands for 1min, then charged to 3.65V at a constant current of 0.1C, stands for 30min, discharged to 2.0V at a constant current of 0.33C, records the discharge capacity A0, unit Ah, then charges 0.5A0Ah at a constant current of 0.33C, adjusts the SOC to 50%. After the battery cell is placed at 25℃ for 2h, it is discharged at a constant current of 3C for 10s, records the ΔU discharge, ΔI discharge, and the discharge DCR data of the lithium-ion battery is calculated by the following formula, R discharge = ΔU discharge / ΔI discharge, wherein ΔU discharge represents the voltage change within 10s at the beginning of discharge, and ΔI discharge represents the current value within 10s at the beginning of discharge.

[0317] 2, charging time of 10% to 80% SOC

[0318] Charging time test: ① Voltage calibration: 1) The positive electrode sheet, negative electrode sheet, separator and electrolyte in the example or comparative example were prepared into a stacked three-electrode battery, which was placed at 25 °C for 30 min; 2) The battery monomer was charged to a charging cutoff voltage of 3.65 V at 0.33 C at 25 °C, and then constant voltage charging was continued at the charging cutoff voltage until the current was 0.05 C, and the charging cutoff (wherein C represents the rated capacity of the battery monomer); 3) 25 °C for 1 h; 4) The battery monomer was discharged to a discharge cutoff voltage of 2.5 V at 0.33 C at 25 °C, and the total discharge capacity C0 discharged by the battery monomer was recorded; 5) 25 °C for 1 h. ② Normal temperature charging test: 1) The positive electrode sheet, negative electrode sheet, separator and electrolyte in the example or comparative example were prepared into a stacked three-electrode battery, which was placed for 30 min; 2) 0.33 C0 direct current discharge to the discharge cutoff voltage of 2.5 V, which corresponds to 0% SOC at this time; 3) 5 min of standing; 4) 5C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C1 at this time, which corresponds to C1 / C0 SOC at this time; 5) 5 min of standing; 6) 4.5C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C2 at this time, which corresponds to C2 / C0 SOC at this time; 7) 5 min of standing; 8) 4C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C3 at this time, which corresponds to C3 / C0 SOC at this time; 9) 5 min of standing; 10) 3C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C4 at this time, which corresponds to C4 / C0 SOC at this time; 11) 5 min of standing; 12) 2C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C5 at this time, which corresponds to C5 / C0 SOC at this time; 13) 5 min of standing; 14) 1C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C6 at this time, which corresponds to C6 / C0 SOC at this time; 15) 5 min of standing; 16) 0.8C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C7 at this time, which corresponds to C7 / C0 SOC at this time; 17) 5 min of standing; 18) 0.5C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C8 at this time, which corresponds to C8 / C0 SOC at this time; 19) 5 min of standing; 20) 0.33C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C9 (also C0) at this time, which corresponds to 100% SOC. The total charging time from 10% SOC to 80% SOC charging process is added to obtain the required charging time.

[0319] 3. Volume energy density

[0320] The battery monomer was discharged at 0.33 C to 2.5 V at 25 DEG C, rested for 5 min, charged to the upper limit cut-off voltage 3.65 V at 0.33 C, and then charged to a current of 0.05 C at constant voltage, rested for 5 min; discharged to the cut-off voltage 2.5 V at 0.33 C, and the discharge capacity at this time was recorded to obtain the discharge energy E0. The volumetric energy density (Wh / L) = discharge energy E0 / monomer volume (L).

[0321] 4. Cycle performance

[0322] Charged to 3.65 V at 0.5 C, then charged to 0.05 C at constant voltage at 3.65 V, rested for 10 min, and then discharged to 2.5 V at 1 C, rested for 10 min, which was one cycle, until the battery capacity decayed to 80% of the nominal capacity, the test was stopped, and the cycle number @ 80% SOH was recorded.

[0323] II. Analysis of test results of each example and comparative example

[0324] The battery monomers of each example and comparative example were prepared according to the above method, and each performance parameter was measured, and the results are shown in Table 5 below.

[0325] Table 1. Preparation parameters of negative electrode sheet

[0326] Table 2. Preparation parameters of positive electrode sheet

[0327] Table 3. Preparation parameters of electrolyte

[0328] Table 4. Preparation parameters of electrolyte

[0329] Table 5. Battery performance parameters

[0330] In the battery monomers of Examples 1-13, the lithium-containing phosphate containing an olivine structure was used as the positive electrode active material in the positive electrode film layer, and the graphite with an average particle size Dv50 of 8-15 μm was used as the negative electrode active material in the negative electrode film layer; and as shown in FIG. 4, in the cross section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate contains first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1-3 μm; therefore, the battery monomers prepared in Examples 1-13 all have excellent fast charging performance, energy density, cycle performance, and low direct current internal resistance.

[0331] The average particle size Dv50 of the graphite in the negative electrode film layer of Comparative Examples 1-2 is out of the range of 8-15 μm, in which: the Dv50 of the graphite in Comparative Example 1 is too large, and the Dv50 of the graphite in Comparative Example 2 is too small.

[0332] It can be seen from the comparison of Comparative Examples 1-2 and Examples 1-13 that: when the average particle size Dv50 of the graphite is greater than 15 μm, the fast-charging performance and the direct-current internal resistance of the battery cell cannot be effectively improved; and when the average particle size Dv50 of the graphite is less than 8 μm, the cycle performance of the battery cell cannot be effectively improved, and the energy density is also reduced; therefore, when the average particle size Dv50 of the graphite in the negative electrode film layer is in the range of 8-15 μm, the cycle performance, the fast-charging performance, the direct-current internal resistance and the energy density of the battery are improved, and when the average particle size Dv50 of the graphite is out of the range, the comprehensive performance of the battery is poor.

[0333] In the positive electrode film layer of Comparative Example 3, the lithium-containing phosphate contains second lithium-containing phosphate particles with a longest diameter of 1-3 μm, but does not contain first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 μm.

[0334] It can be seen from the comparison of Comparative Example 3 and Examples 1-13 that: when the lithium-containing phosphate in the positive electrode film layer is not used in the size grading manner, but only the particles with a larger particle size (the longest diameter is 1-3 μm) are used, the improvement effect on the fast-charging performance and the direct-current internal resistance of the battery is limited, and the energy density is deteriorated.

[0335] In the positive electrode film layer of Comparative Example 4, the lithium-containing phosphate contains first lithium-containing phosphate particles with a longest diameter of 0.05-0.3 μm, but does not contain second lithium-containing phosphate particles with a longest diameter of 1-3 μm.

[0336] It can be seen from the comparison of Comparative Example 4 and Examples 1-13 that: when the lithium-containing phosphate in the positive electrode film layer is not used in the size grading manner, but only the particles with a smaller particle size (the longest diameter is 0.05-0.3 μm) are used, the compaction density of the electrode plate is low, and therefore the energy density is deteriorated. Therefore, when the lithium-containing phosphate in the positive electrode film layer is used in the size grading manner of the particles with a smaller particle size (the longest diameter is 0.05-0.3 μm) and the particles with a larger particle size (the longest diameter is 1-3 μm), the energy density, the cycle performance, the fast-charging performance and the direct-current internal resistance of the battery are improved, and when the lithium-containing phosphate is out of the range, the comprehensive performance of the battery is poor.

[0337] In Examples 1-5, the average particle size Dv50 of the graphite in the negative electrode film layer is in the range of 8-15 μm, and the battery cells prepared therefrom can have excellent energy density, fast charging performance, cycle performance, and low direct current resistance. In addition, the results show that when the Dv50 of the graphite gradually increases in the range of 8-15 μm, the cycle performance of the battery is improved to some extent, but the fast charging performance is decreased to some extent and the direct current resistance is increased to some extent; when the Dv50 of the graphite gradually decreases in the range of 8-15 μm, the fast charging performance of the battery is improved to some extent and the direct current resistance is decreased to some extent, but the cycle performance is decreased to some extent. Therefore, only when the Dv50 of the graphite in the negative electrode film layer is in the range of 8-15 μm, the fast charging performance, cycle performance, and direct current resistance of the battery can be improved, and when the Dv50 of the graphite is in the range of 9.5-11.5 μm, the comprehensive performance of the battery is better. When the Dv50 of the graphite is too low, the energy density of the battery is reduced.

[0338] In Examples 1 and 6, the lithium-containing phosphate in the positive electrode film layer comprises first lithium-containing phosphate particles having a longest diameter of 0.05-0.3 μm and second lithium-containing phosphate particles having a longest diameter of 1-3 μm, and the battery cells prepared therefrom can have excellent energy density, fast charging performance, cycle performance, and low direct current resistance. In addition, it can be seen from the comparison between Example 1 and Example 6 that when the number of the first lithium-containing phosphate particles having a longest diameter of 0.05-0.3 μm is greater than the number of the second lithium-containing phosphate particles having a longest diameter of 1-3 μm, the direct current resistance and fast charging performance of the battery can be further improved, and the comprehensive performance of the battery is better.

[0339] In Examples 1, 7-10, the electrolyte has the following formulation, and the battery cells prepared therefrom can have excellent energy density, fast charging performance, cycle performance, and low direct current resistance: linear carboxylic acid ester (e.g., ethyl acetate) with a mass fraction of 40-75%, linear carbonate (e.g., DMC, EMC) with a mass fraction of 10-40%, and cyclic carbonate (e.g., ethylene carbonate) with a mass fraction of 5-15%, wherein the mass fraction of dimethyl carbonate is 5-15%, and the mass ratio of linear carboxylic acid ester (e.g., ethyl acetate) to dimethyl carbonate is 2.0-7.0; LiPF6 and LiFSI with a mass fraction of 13-20%, and the mass ratio of LiPF6 to LiFSI is 1.2:1-2:1.

[0340] Meanwhile, it can be seen from the comparison between Examples 1, 7, and 8 that as the proportion of linear carboxylic acid ester (e.g., ethyl acetate) and LiFSI in the electrolyte gradually increases, the fast charging performance and direct current resistance of the battery are further improved; and as the proportion of linear carbonate (e.g., DMC) and LiPF6 in the electrolyte gradually increases, the cycle performance of the battery is further improved.

[0341] Meanwhile, it can be seen from the comparison of Examples 1, 9, 10 that when only linear carboxylic acid ester (such as ethyl acetate) exists in the organic solvent of the electrolyte, no carbonic acid ester exists, and only LiFSI exists in the lithium salt, no LiPF6 exists, the fast charging performance and the direct current internal resistance of the battery are further improved, and the cycle performance of the battery is poor; when only linear carbonic acid ester (such as DMC) exists in the organic solvent of the electrolyte, no linear carboxylic acid ester exists, and only LiPF6 exists in the lithium salt, no LiFSI exists, the cycle performance of the battery is further improved, but the improvement of the fast charging performance and the direct current internal resistance is limited. Therefore, when the linear carbonic acid ester and the linear carboxylic acid ester in the above mass ratio are used as the organic solvent in the electrolyte at the same time, and the LiPF6 and the LiFSI in the above mass ratio are used as the lithium salt at the same time, by matching the various solvents and lithium salts with each other, the fast charging performance, the direct current internal resistance and the cycle performance of the battery can be further improved, and the comprehensive performance of the battery is better.

[0342] In Examples 1 and 11, at least one layer of graphite is contained in the negative electrode film layer as the negative electrode active material, and the average particle size Dv50 thereof is in the range of 8 μm to 15 μm, and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance. In addition, it can be seen from the comparison of Example 1 and Example 11 that when the negative electrode film layer includes two layers of artificial graphite having different particle sizes as the negative electrode active material layer (the first negative electrode active material layer is arranged on the surface of the negative electrode current collector, and the second negative electrode active material layer is arranged on the side of the first negative electrode active material layer away from the negative electrode current collector, and the Dv50 of the first negative electrode active material layer is greater than that of the second negative electrode active material layer), the fast charging performance and the direct current internal resistance of the battery can be further improved, and the comprehensive performance of the battery is better.

[0343] In Examples 1, 12-13, 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, and 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, and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance. In addition, the results also show that when the ratio of the single-sided thickness of the positive and negative electrode film layers to the thickness of the positive and negative electrode current collectors gradually increases within the above range, the energy density of the battery can be further improved; when the ratio of the single-sided thickness of the positive and negative electrode film layers to the thickness of the positive and negative electrode current collectors gradually decreases within the above range, the fast charging performance, the direct current internal resistance, and the cycle performance of the battery can be further improved.

[0344] In Examples 1-13, the specific surface area of the graphite in the positive electrode film layer is 3 m 2 / g to 8 m 2 / g, and the compaction density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3, the compaction density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 The prepared battery cell can have excellent energy density, fast charging performance, cycle performance, and low direct current resistance.

[0345] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration as the technical idea and exerting the same effects within the scope of the technical solution of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications that can be thought of by those skilled in the art to the embodiments or by combining part of the constituent elements of the embodiments are also included in the scope of the present application without departing from the gist of the present application.

Claims

1. A battery cell, characterized by, The battery includes a positive electrode sheet, a negative electrode sheet, and a separator film between the positive electrode sheet and the negative electrode sheet, characterized in that The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material, the positive electrode active material including a lithium-containing phosphate of an olivine structure; In a cross section of the positive electrode film layer in a thickness direction, the lithium-containing phosphate of the olivine structure 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; The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material, the negative electrode active material having an average particle size Dv50 of 8 μm to 15 μm, the negative electrode active material including graphite.

2. The battery cell of claim 1, wherein, The negative electrode active material has an average particle size Dv50 of 9.5 μm to 11.5 μm.

3. The battery cell according to claim 1 or 2, characterized in that, The specific surface area of the negative active material is 3 m 2 / g to 8 m 2 / g.

4. The battery cell according to claim 1 or 2, characterized in that, The specific surface area of the negative active material is 4 m 2 / g to 6 m 2 / g.

5. The battery cell according to any one of claims 1 to 4, characterized in that, In the cross section of the positive electrode film layer in the thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The lithium-containing phosphate of olivine structure has a general composition according to 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, Ce; X includes one or more of S, Si, Cl, B, C, and N; and Y includes one or more of O and F.

7. The battery cell of claim 6, wherein, M includes one or more of Al, Ti, V, and Mg.

8. The battery cell according to claim 6 or 7, characterized in that The positive electrode active material satisfies at least one of the following conditions: (1) the positive electrode active material contains Al, 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, 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, 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, the mass content of which is 0.001-0.01%, based on the total mass of the positive electrode active material.

9. The battery cell of any one of claims 1 to 8, wherein, The compacted density of the positive electrode plate is 2.3 g / cm 3 to 2.6 g / cm 3 .

10. The battery cell of any one of claims 1 to 8, wherein, The compacted density of the positive electrode plate is 2.4 g / cm 3 to 2.55 g / cm 3 .

11. The battery cell of any one of claims 1 to 10, wherein, The areal density of the positive electrode film layer on one side is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 .

12. The battery cell of any one of claims 1 to 10, wherein, The areal density of the single-sided positive electrode film layer is 0.335 g / 1540.25 mm 2 to 0.38 g / 1540.25 mm 2 .

13. The battery cell of any one of claims 1 to 12, wherein, The thickness of the positive electrode current collector is 10 μm to 15 μm.

14. The battery cell of any one of claims 1 to 13, wherein, The ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 5 to 12.

15. The battery cell of any one of claims 1 to 13, wherein, The ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 6 to 10.

16. The battery cell of any one of claims 1 to 15, wherein, The compacted density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 .

17. The battery cell of any one of claims 1 to 15, wherein, The compacted density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm 3 .

18. The battery cell of any one of claims 1 to 17, wherein, The areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 .

19. The battery cell of any one of claims 1 to 17, wherein, The areal density of the negative electrode film layer on one side is 0.15 g / 1540.25 mm 2 to 0.165 g / 1540.25 mm 2 .

20. The battery cell of any one of claims 1-19, wherein, The thickness of the negative electrode current collector is 4 μm to 6 μm.

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

22. The battery cell of any one of claims 1-20, wherein, A ratio of a single-face thickness of the negative electrode film layer to a thickness of the negative electrode current collector is 13 to 20.

23. The battery cell of any one of claims 1-22, wherein, 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 first negative electrode active material layer away from the negative electrode current collector, the negative electrode active material in the first negative electrode active material layer includes a first artificial graphite, and the negative electrode active material in the second negative electrode active material layer includes a second artificial graphite.

24. The battery cell of claim 23, wherein, The average particle diameter Dv50 of the first artificial graphite is 11 to 15 mu m.

25. The battery cell of claim 23, wherein, The average particle diameter Dv50 of the second artificial graphite is 8 to 15 mu m.

26. The battery cell of claim 23, wherein, The average particle diameter Dv50 of the second artificial graphite is 9.5 to 11.5 mu m.

27. The battery cell of any one of claims 1-26, wherein, The battery cell further includes an electrolyte, the electrolyte includes an organic solvent, and the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

28. The battery cell of claim 27, wherein, The organic solvent includes a linear carboxylic acid ester, and a mass percentage of the linear carboxylic acid ester is 40% to 75% based on a total mass of the electrolyte.

29. The battery cell of claim 28, wherein, The linear carboxylic acid ester has a general structure of R1-COO-R2, where R1 and R2 each independently include one or more of C1 to C5 alkyl and C1 to C5 haloalkyl.

30. The battery cell of claim 29, wherein, The linear carboxylic acid ester includes one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

31. The battery cell of any one of claims 27-30, wherein, The organic solvent includes a carbonate solvent, the carbonate solvent includes a linear carbonate and a cyclic carbonate, and a mass percentage of the linear carbonate is 10% to 40% based on a total mass of the electrolyte.

32. The battery cell of claim 31, wherein, The cyclic carbonate includes one or more of vinyl carbonate and propylene carbonate, and the linear carbonate includes one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

33. The battery cell of claim 32, wherein, The linear carbonate includes dimethyl carbonate, and a mass percentage of the dimethyl carbonate is 5% to 15% based on a total mass of the electrolyte.

34. The battery cell of any one of claims 27-33, wherein, The organic solvent includes dimethyl carbonate and a linear carboxylic acid ester, and a mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 2.0 to 7.

0.

35. The battery cell of any one of claims 27-33, wherein, The mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.

0.

36. The battery cell of any one of claims 27-35, wherein, The electrolyte further includes a lithium salt, and a mass percentage of the lithium salt is 13% to 20% based on a total mass of the electrolyte.

37. The battery cell of claim 36, wherein, The lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and a fluorine-containing sulfonimide salt, and the fluorine-containing sulfonimide salt includes one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis-trifluoromethylsulfonylimide LiTFSI.

38. The battery cell of claim 36, wherein, The lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonylimide LiFSI.

39. The battery cell of any one of claim 38, wherein, In the electrolyte, a mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfonylimide LiFSI is 1.2:1 to 2:

1.

40. The battery cell of any one of claims 27-39, wherein, The electrolyte includes a carbonate-based additive, and the carbonate-based additive includes fluoroethylene carbonate FEC and vinylene carbonate VC.

41. The battery cell of claim 40, wherein, The mass percentage of the carbonate-based additive in the electrolyte is 0.5% to 7%, based on the total mass of the electrolyte.

42. The battery cell of either claim 40 or 41, wherein, The electrolyte comprises vinylene carbonate VC, and the mass percentage of the vinylene carbonate VC in the electrolyte is 0.5% to 2%, based on the total mass of the electrolyte.

43. The battery cell of either claim 40 or 41, wherein, The electrolyte comprises fluoroethylene carbonate FEC, and the mass percentage of the fluoroethylene carbonate FEC in the electrolyte is 0.1% to 1%, based on the total mass of the electrolyte.

44. The battery cell of any one of claims 1-43, wherein, The positive current collector comprises a positive current collecting part and at least two positive tabs arranged on the same side of the positive current collecting part, the positive tabs extending from the positive current collecting part along a first direction, wherein the distance between the center lines of two adjacent positive tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction; and / or the negative current collector comprises a negative current collecting part and at least two negative tabs arranged on the same side of the negative current collecting part, the negative tabs extending from the negative current collecting part along a first direction, wherein the distance between the center lines of two adjacent negative tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction.

45. The battery cell of claim 44, wherein, The distance between the center lines of two adjacent positive tabs is 20 mm to 330 mm; and / or The distance between the center lines of two adjacent negative tabs is 20 mm to 330 mm.

46. The battery cell of claim 44, wherein, The battery monomer further comprises a top cover, the top cover comprising a positive electrode terminal and a negative electrode terminal with opposite polarities, the positive electrode terminal and the negative electrode terminal being respectively used for electrical connection with the positive tab and the negative tab.

47. The battery cell of any one of claims 44-46, wherein, The size of the positive electrode film layer along the first direction is W1 mm, and the size of the negative electrode film layer along the first direction is W2 mm, wherein W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm.

48. The battery cell of any one of claims 1-47, wherein, The battery monomer further comprises a shell, the shell being square-shaped, the thickness of the shell being 30 mm to 55 mm, the width of the shell being 150 mm to 250 mm, and the height of the shell being 90 mm to 120 mm.

49. The battery cell of any one of claims 1-48, wherein, The battery monomer is configured to have a charging time of 10 min to 17 min from 10% SOC to 80% SOC at room temperature.

50. A battery device, comprising: The battery device comprises at least one of a battery module, a battery pack, and an energy storage device.

51. An electrical device, comprising: The battery device comprises at least one of a battery module, a battery pack, and an energy storage device.

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