Battery cells, battery devices, and power-consuming devices

Abstract

The present application relates to a battery cell, a battery device and an electrical device, wherein the battery cell includes an electrode assembly and a shell assembly, the electrode assembly includes a plurality of first and second pole pieces, the first and second pole pieces include a coating portion and a pole ear portion, the pole ear portion is connected to the coating portion and extends out of the coating portion; the shell assembly includes a shell, at least one first electrode terminal and a second electrode terminal, the shell accommodates the electrode assembly, the first electrode terminal is connected to the pole ear portion of the first pole piece, and the second electrode terminal is connected to the pole ear portion of the second pole piece, wherein one of the first and second pole pieces is a positive pole piece and the other is a negative pole piece, the positive pole piece includes a lithium-containing phosphate with an olivine structure; the ratio of the dimension of the coating portion of the positive pole piece along the length direction of the battery cell to the dimension of the coating portion of the positive pole piece along the width direction of the battery cell is 4 to 7; the battery cell satisfies: (x1×S1+x2×S2) / E is 0.4 to 1.4.

Description

[0001] This application claims priority to international patent application PCT / CN2025 / 071057, filed on January 7, 2025, entitled “Battery Cell, Battery Device, and Electrical Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to a battery cell, a battery device and an electrical device. Background Art

[0003] Battery cells, with their high capacity and long lifespan, are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy planes, and power tools. As batteries have advanced significantly, so too have the demands for higher performance. However, the fast charging capability and energy density of battery cells need to be further improved. Summary of the Invention

[0004] The present application provides a battery cell, a battery device, and an electrical device. The fast charging capability and energy density of the battery cell of the present application can be further improved.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, the battery cell comprising an electrode assembly and a housing assembly, the electrode assembly comprising a plurality of first pole pieces and a plurality of second pole pieces, the first pole pieces and the second pole pieces being stacked along a thickness direction of the battery cell, the first pole piece and the second pole piece each comprising a coating portion and a pole ear portion, the coating portion being provided with an active material layer, the pole ear portion being connected to the coating portion and extending out of the coating portion; the housing assembly comprising a housing and a terminal assembly disposed on the housing, the housing accommodating the electrode assembly, the terminal assembly comprising at least one first electrode terminal and at least one second electrode terminal, the first electrode terminal being connected to the pole ear portion of the first pole piece, and the second electrode terminal being connected to the pole ear portion of the second pole piece,

[0006] One of the first and second electrode sheets is a positive electrode sheet, and the other is a negative electrode sheet; the active material layer of the positive electrode sheet includes a lithium-containing phosphate with an olivine structure; a dimension of a coated portion of the positive electrode sheet along a length direction of the battery cell is a first dimension, a dimension of the coated portion of the positive electrode sheet along a width direction of the battery cell is a second dimension, and a ratio of the first dimension to the second dimension is 4 to 7;

[0007] The battery cell meets the following requirements: (x1×S1+x2×S2) / E is 0.4 to 1.4,

[0008] x1 represents the number of first electrode terminals;

[0009] x2 represents the number of second electrode terminals;

[0010] S1 represents the minimum cross-sectional area of ​​a single first electrode terminal perpendicular to its own thickness direction, and its unit is mm 2 ;

[0011] S2 represents the minimum cross-sectional area of ​​a single second electrode terminal perpendicular to its own thickness direction, and its unit is mm 2 ;

[0012] E represents the single cell energy of the battery cell, and its unit is Wh.

[0013] Therefore, in an embodiment of the present application, the ratio of the size of the coating portion of the positive electrode plate along the length direction to the size of the coating portion of the positive electrode plate along the width direction is 4 to 7, and the length of the coating portion is relatively long, which is conducive to carrying relatively more positive electrode active materials and making the battery cell have a relatively high energy density; when the length of the coating portion is relatively long, the electron transmission path in the length direction is longer, the internal resistance is relatively high, and it is not conducive to fast charging, and the positive electrode active material includes lithium-containing phosphate with relatively poor conductivity, which further increases the internal resistance of the positive electrode plate; in order for the battery cell to quickly store more single cell energy, when (x1×S1+x2×S2) / E is greater than or equal to 0.4, the current capacity of the first electrode terminal and the second electrode terminal is relatively strong, and electrons can be quickly conducted, effectively reducing the internal resistance of the battery cell and reducing the heat generation of the battery cell, thereby improving the fast charging capability of the battery cell, so that the battery cell reaches the required capacity under fast charging.

[0014] In some embodiments, S1 is 15 to 60. When the flow area of ​​the first electronic terminal is within the above range, its flow capacity is relatively strong, which can improve the fast charging capability of the battery cell.

[0015] In some embodiments, S2 is 15 to 60. When the flow area of ​​the second electronic terminal is within the above range, its flow capacity is relatively strong, which can improve the fast charging capability of the battery cell.

[0016] In some embodiments, x1 is 1 to 4; as the number of first electrode terminals increases, the overcurrent capability of all first electrode terminals is enhanced, which can improve the fast charging capability of the battery cells.

[0017] In some embodiments, x2 is 1 to 4. As the number of second electrode terminals increases, the overcurrent capability of all second electrode terminals is enhanced, which can improve the fast charging capability of the battery cells.

[0018] In some embodiments, the battery cell further satisfies: M1 / E is 0.2 to 0.6; M1 represents the area of ​​the first connecting region, and its unit is mm 2 ; The first connection area is the area of ​​at least one first electrode terminal connected to the pole ear portion of the first pole piece.

[0019] Therefore, in the embodiment of the present application, when the battery cell meets the above conditions, the current conduction capability of the first electrode terminal and the pole ear portion of the first pole piece is relatively strong, which is beneficial to reducing the internal resistance of the battery cell and reducing the heat generation of the battery cell, thereby improving the fast charging capability of the battery cell, so that the battery cell reaches the required capacity under fast charging.

[0020] In some embodiments, the battery cell further satisfies: M2 / E is 0.2 to 0.6; M2 represents the area of ​​the second connecting region, and its unit is mm 2 ; The second connection area is the area of ​​at least one second electrode terminal connected to the pole ear portion of the second pole piece.

[0021] Therefore, in the embodiment of the present application, when the battery cell meets the above conditions, the current conduction capability of the first electrode terminal and the pole ear portion of the first pole piece is relatively strong, which is beneficial to reducing the internal resistance of the battery cell and reducing the heat generation of the battery cell, thereby improving the fast charging capability of the battery cell, so that the battery cell reaches the required capacity under fast charging.

[0022] In some embodiments, M1 is 60 to 120; the current conduction capability of the first electrode terminal and the first electrode tab is relatively strong, which is beneficial to reducing the internal resistance of the battery cell and reducing the heat generation of the battery cell, thereby improving the fast charging capability of the battery cell.

[0023] In some embodiments, M2 is 60 to 120. The second electrode terminal and the second tab have strong current conductivity, which is beneficial to reducing the internal resistance of the battery cell and reducing the heat generation of the battery cell, thereby improving the fast charging capability of the battery cell.

[0024] In some embodiments, E is 170 to 480. When the battery cell meets the above conditions, the energy density of the battery cell is relatively high.

[0025] In some embodiments, the first electrode terminal is disposed on at least one side of the electrode assembly along the length direction, which helps to reduce the space occupied by the first electrode terminal and improve the energy density of the battery cell.

[0026] In some embodiments, the second electrode terminal is disposed on at least one side of the electrode assembly along the length direction, which helps to reduce the space occupied by the second electrode terminal and improve the energy density of the battery cell.

[0027] In some embodiments, there are at least two first electrode terminals, and the at least two first electrode terminals are respectively arranged on both sides of the electrode assembly along the length direction; the transmission path of electrons in the length direction is shortened, which is beneficial to reducing impedance and improving the fast charging capability of the battery cell.

[0028] In some embodiments, there are at least two second electrode terminals, each disposed on either side of the electrode assembly along its length. This shortens the electron transmission path along its length, thereby reducing impedance and improving the rapid charging capability of the battery cell.

[0029] In some embodiments, the housing includes a shell and an end cap, the shell accommodates the electrode assembly, the shell includes an opening, the end cap covers the opening, and the first electrode terminal is disposed on the end cap.

[0030] In some embodiments, the first electrode terminal includes a first main portion and a first protrusion. The first main portion is disposed within the housing and extends through the end cap of the housing. The first protrusion is disposed within the first main portion and protrudes beyond the first main portion to connect to the side of the end cap facing the electrode assembly. This arrangement helps increase the current carrying capacity of the first electrode terminal.

[0031] In some embodiments, a dimension of the first protrusion in a direction from the first main body to the first protrusion is 1.5 mm to 3.0 mm.

[0032] Therefore, when the first protrusion meets the above conditions, the connection area between the first protrusion and the shell is relatively larger, the connection strength is higher, and the structure makes the structure of the battery cell more stable.

[0033] In some embodiments, the first main body and the first protrusion are an integrated structure, which is conducive to increasing the current capacity of the first electrode terminal.

[0034] In some embodiments, the first body portion is disposed on and penetrates the end cover, and a ratio of a dimension of the first body portion along a thickness direction of the battery cell to a dimension of the end cover along the thickness direction of the battery cell is 0.20 to 0.40.

[0035] Therefore, in the embodiment of the present application, when the first main body meets the above conditions, the size of the first main body is relatively high, which is beneficial to improving the current capacity of the first electrode terminal, thereby improving the fast charging performance.

[0036] In some embodiments, the housing assembly further includes a first conductive fixing member, at least partially located on a side of the end cap facing away from the electrode assembly. The first conductive fixing member surrounds the first main body and securely connects the first main body and the end cap. The first conductive fixing member can increase the flow capacity with the external bus assembly, thereby improving fast charging performance.

[0037] In some embodiments, the ratio of the dimension of the first conductive fixing member along the thickness direction of the battery cell to the dimension of the end cap along the thickness direction of the battery cell is 0.40 to 0.80. The first conductive fixing member can increase the flow capacity with the external bus assembly and improve the fast charging performance.

[0038] In some embodiments, the tab portion of the first pole piece is disposed on at least one side of the coating portion along a first direction. The first pole piece satisfies the following conditions: n*W1 / W2 is 0.5 to 1.0; n represents the number of tab portions located on the same side of the coating portion; W1 represents the average dimension of the tab portion along a second direction; one of the first and second directions is parallel to the length of the battery cell, and the other is parallel to the width of the battery cell; and W2 represents the dimension of the coating portion along the second direction. The tab portion has a strong current-carrying capacity, which helps improve the current-carrying capacity of the battery device and the fast-charging performance of the battery device.

[0039] In some embodiments, the first direction is parallel to a length direction of the battery cell.

[0040] In some embodiments, the first pole piece includes a plurality of pole lugs. The pole lugs have a strong current-carrying capacity, which is beneficial for improving the current-carrying capacity of the battery device and the fast-charging performance of the battery device.

[0041] In some embodiments, there are at least two pole lugs on the same side of the coating portion of the first pole piece. The above arrangement shortens the electron transmission path, which is beneficial for improving the fast charging capability.

[0042] In some embodiments, the plurality of pole lugs of the first pole piece are located on both sides of the coating portion along the first direction. The above arrangement shortens the electron transmission path, which is beneficial to improving the fast charging capability.

[0043] In some embodiments, all the tabs of the first pole piece are located on the same side of the coating portion along the first direction. The tabs have a stronger current carrying capacity, which is beneficial for improving the current carrying capacity of the battery device and the fast charging performance of the battery device.

[0044] In some embodiments, a ratio of the length of the battery cell to the thickness of the battery cell is 40 to 70.

[0045] In some embodiments, a ratio of the width of the battery cell to the thickness of the battery cell is 3 to 15.

[0046] In some embodiments, the thickness of the battery cell is 10 mm to 30 mm. When the thickness of the battery cell is within the above range, the thickness of the battery cell is relatively small, which is conducive to rapid heat dissipation inside the battery cell and reduces the risk of thermal runaway.

[0047] In some embodiments, the olivine-structured lithium-containing phosphate includes lithium iron phosphate. Lithium iron phosphate has excellent cycle stability and can improve the cycle performance of battery cells under fast charging.

[0048] In some embodiments, the active material layer of the positive electrode sheet is a positive electrode film layer, and the single-side coating weight of the positive electrode film layer is 250 mg / 1540.25 mm 2 Up to 330mg / 1540.25mm 2 When the single-sided coating weight of the positive electrode film layer is within the above range, the heat generated per unit area of ​​the positive electrode sheet will not be too large, and both the energy density and the charge rate performance of the battery cell can be improved.

[0049] In some embodiments, the compaction density of the positive electrode film layer of the battery cell at 0% state of charge is 2.30 g / cm 3 to 2.70g / cm 3 When the compaction density of the positive electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and because the positive electrode active material of the positive electrode film layer is stacked relatively densely, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation under fast charging.

[0050] In some embodiments, the active material layer of the negative electrode sheet is a negative electrode film layer, and the single-side coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 Up to 180mg / 1540.25mm 2 When the single-sided coating weight of the negative electrode film layer is within the above range, the heat generated per unit area of ​​the negative electrode sheet will not be too large, and the energy density of the battery cell can be improved.

[0051] In some embodiments, the compaction density of the negative electrode film layer of the battery cell at 0% state of charge is 1.30 g / cm 3 Up to 1.65g / cm 3 When the compaction density of the negative electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and because the negative electrode active material in the negative electrode film layer is relatively densely packed, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation.

[0052] In some embodiments, the coating portion of the negative electrode plate includes a negative electrode current collecting portion and a negative electrode film layer disposed on at least one side of the negative electrode current collecting portion, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, wherein the first negative electrode film layer is disposed on the surface of the negative electrode current collecting portion; and the second negative electrode film layer is connected to the side of the first negative electrode film layer facing away from the negative electrode current collecting portion, wherein the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is greater than or equal to the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer. In the embodiments of the present application, the particle size of the second negative electrode film layer is relatively small, which can shorten the solid-phase transmission path of lithium ions, improve fast charging performance, and improve the problem of lithium plating on the surface of the negative electrode plate.

[0053] In some embodiments, the carbon-based material of the first negative electrode film layer is granular, and its volume average particle size Dv50 is 9.5 μm to 18.5 μm; when the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is within the above range, on the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance; on the other hand, the material is not easy to agglomerate during the preparation process, which can improve the stability of the material.

[0054] In some embodiments, the carbon-based material of the second negative electrode film layer is granular and has a volume average particle size Dv50 of 7.8 μm to 14.3 μm. When the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is within this range, the solid-phase transport path of lithium ions can be shortened, thereby improving fast charging performance.

[0055] In some embodiments, the carbon-based material of the first negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer includes artificial graphite.

[0056] In some embodiments, the battery cell further includes an electrolyte having a conductivity of 10 mS / cm to 13 mS / cm at room temperature. The high migration rate of lithium ions in the electrolyte can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0057] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes a chain carboxylate solvent. The chain carboxylate solvent improves the conductivity of the electrolyte at room temperature, which is beneficial to the migration of lithium ions.

[0058] In some embodiments, based on the mass of the electrolyte, the mass content of the chain carboxylate solvent is 5% to 30%, so that the conductivity of the electrolyte is relatively high, which is conducive to the migration of lithium ions.

[0059] In some embodiments, the electrolyte includes a lithium salt, including lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide. The ratio of the mass content of lithium hexafluorophosphate to the mass content of lithium bis(fluorosulfonyl)imide is 0.5 to 4 based on the mass of the electrolyte. When the lithium salt meets the above conditions, the system is relatively stable and not easily decomposed. The lithium salt is beneficial for improving the conductivity of the electrolyte and enhancing the dynamic performance of the battery cell.

[0060] In some embodiments, the mass content of lithium bis(fluorosulfonyl)imide in the electrolyte is 1% to 15%. When the lithium salt meets the above conditions, the system is relatively stable and not easily decomposed. The lithium salt is beneficial for improving the conductivity of the electrolyte and enhancing the dynamic performance of the battery cell.

[0061] In a second aspect, an embodiment of the present application further provides a battery device, comprising a battery cell according to any embodiment of the first aspect of the present application.

[0062] In a third aspect, an embodiment of the present application further proposes an electrical device, which includes a battery device as in any embodiment of the second aspect or the third aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0064] Figure 1 is a schematic structural diagram of an electrical device provided in some embodiments of the present application;

[0065] Figure 2 is a schematic structural diagram of a battery pack provided in some embodiments of the present application;

[0066] Figure 3 is a schematic structural diagram of a battery module provided in some embodiments of the present application;

[0067] Figure 4 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0068] Figure 5 is a schematic structural diagram of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0069] Figure 6 Schematic diagram of the structure of the end cover, terminal assembly and first conductive fixing member of the battery cell provided in some embodiments of the present application;

[0070] Figure 7 yes Figure 6 Schematic top view of

[0071] Figure 8 yes Figure 7 Sectional view along line AA;

[0072] Figure 9 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application;

[0073] Figure 10 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0074] Figure 11 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0075] Figure 12 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0076] Figure 13 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0077] Figure 14 is a schematic diagram of a first pole piece of a battery cell provided in some embodiments of the present application;

[0078] Figure 15 is a schematic diagram of a first pole piece of a battery cell provided in some other embodiments of the present application;

[0079] Figure 16 is a schematic diagram of a first pole piece of a battery cell provided in some other embodiments of the present application;

[0080] Figure 17 is a schematic diagram of a first pole piece of a battery cell provided in some other embodiments of the present application;

[0081] Figure 18 Schematic diagram of the first pole piece of a battery cell provided in some other embodiments of the present application.

[0082] The drawings are not necessarily drawn to scale.

[0083] The following are the descriptions of the reference numerals:

[0084] X, thickness direction; Y, width direction; Z, length direction;

[0085] 1. Power-consuming device; 2. Battery pack; 3. Controller; 4. Motor; 5. Box; 5a. First box portion; 5b. Second box portion; 5c. Accommodation space; 6. Battery module;

[0086] 7. Battery cells;

[0087] 10. Electrode assembly;

[0088] 11. first pole piece; 111. first pole tab; 1111. first end; 112. first coating portion;

[0089] 12. Second pole piece; 121. Second pole tab; 122. Second coating portion;

[0090] 13. Isolation parts;

[0091] 20. Housing assembly;

[0092] 21. Shell; 211. First shell portion; 212. Second shell portion; 2121. First wall; 2122. Second wall; 213. Third shell portion;

[0093] 22. End cap;

[0094] 31. First electrode terminal; 311. First protrusion; 312. First main body;

[0095] 32. a second electrode terminal;

[0096] 41. a first conductive fixing member;

[0097] 51, first adapter; 511, first adapter portion; 512, second adapter portion;

[0098] 61, first conductive member; 611, first conductive portion; 612, second conductive portion;

[0099] 81. A first heat conducting member. DETAILED DESCRIPTION

[0100] Below, the embodiments of the battery cells, battery devices, and electrical devices of the present application are described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0101] " Range " disclosed in this application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3,4 and 5 are listed, then the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In this application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, a numerical range of "0 to 5" indicates that all real numbers between "0 and 5" are listed herein, and "0 to 5" is merely an abbreviation for a combination of these values. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0102] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0103] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0104] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may further include step (c), which indicates that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0105] The term "plurality" used in this application refers to two or more (including two).

[0106] A battery cell includes an electrode assembly and an electrode terminal. When the energy density is relatively high, the overcurrent capacity during charging is poor, which increases the internal resistance of the battery cell and the heat generation, which is not conducive to the rapid charging of the battery cell.

[0107] In view of the above problems, the embodiment of the present application adopts a positive electrode plate of a specific size, so that the positive electrode plate can carry more active materials and improve the energy density of the battery cell; on the basis of high energy density, it is beneficial for the battery cell to store relatively more single cell energy; however, the above-mentioned positive electrode plate is a narrow and long plate, and the electron transmission path in the length direction is long, which easily increases the internal resistance; in order to quickly store more single cell energy in the battery cell, the embodiment of the present application also improves the overcurrent capacity of all electrode terminals. The total overcurrent capacity of all electrode terminals is relatively excellent, which can reduce the internal resistance of the battery cell and enable electrons to migrate quickly, which is beneficial to fast charging and storage capacity.

[0108] The battery cell of the present application is applicable to various battery devices and electrical devices using the battery cell.

[0109] For example, the power-consuming device may be a mobile phone, portable device, laptop computer, electric vehicle, electric toy, electric tool, vehicle, ship, spacecraft, etc. Alternatively, for example, the power-consuming device may be a spacecraft, including an airplane, rocket, space shuttle, and spacecraft.

[0110] Figure 1This is a schematic diagram of the structure of an electric device provided in some embodiments of the present application. The electric device 1 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the electric device 1, a battery pack or battery module can be used.

[0111] A battery device is disposed within the electrical device 1, and the battery device can be disposed at the bottom, head, or tail of the electrical device 1. The battery device can be used to power the electrical device 1. For example, the battery device can serve as an operating power source for the electrical device 1, and can also serve as a driving power source for the electrical device 1, replacing or partially replacing fuel or natural gas to provide driving power for the electrical device 1. Figure 1 The battery device shown in FIG. 1 is a battery pack 2 .

[0112] The electric device 1 may further include a controller 3 and a motor 4 . The controller 3 is used to control the battery device to supply power to the motor 4 , for example, to meet the power requirements of the electric device 1 during startup, navigation, and driving.

[0113] A battery device may include one or more battery cell assemblies to provide voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or in series via a busbar.

[0114] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells.

[0115] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing multiple battery cells to form an independent module. As an example, the battery module may be formed by bundling multiple battery cells with a cable tie.

[0116] like Figure 2 As shown, in some embodiments, the battery device may be a battery pack 2 , which includes a box 5 and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the box 5 .

[0117] As an example, the battery cell assembly may also be housed in the box body 5 by directly fixing a plurality of battery cells to the box body 5 .

[0118] As an example, the housing 5 includes a first housing portion 5a and a second housing portion 5b, which define a storage space 5c. The first housing portion 5a and the second housing portion 5b engage to form a closed space within the housing 5 for accommodating the battery cell assembly. "Enclosed" here means covered or closed, and can be either sealed or unsealed. The first housing portion 5a can be a top cover or a bottom plate.

[0119] As an example, the box body 5 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body 5 to accommodate the battery cell assembly.

[0120] In some embodiments, the box 5 can be used as a part of the chassis structure of the vehicle. For example, part of the box 5 can become at least a part of the floor of the vehicle, or part of the box 5 can become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0121] As an example, the battery cell assembly may be a battery module 6 , and the battery cell assembly may be accommodated in the box body 5 by fixing the battery module 6 in the box body 5 .

[0122] like Figure 3 As shown, the battery module 6 includes a plurality of battery cells 7 .

[0123] In some embodiments, during the process of the battery device charging from a 0% state of charge to a 100% state of charge, the temperature of the external environment of the battery device is room temperature, for example, 25° C.

[0124] In some embodiments, during the charging process of the battery device from 0% state of charge (SOC) to 100% state of charge (SOC), the temperature of the external environment of the battery device is room temperature, for example, 25° C.

[0125] In some embodiments, during the charging process of the battery device or any battery cell 7 constituting the battery device from 10% SOC to 80% SOC, the temperature of the external environment of the battery device is room temperature, for example, 25° C.

[0126] For example, the charging step of the battery device or any battery cell 7 constituting the battery device from 10% SOC to 80% SOC may be performed as follows:

[0127] Charge from 10% SOC to 25% SOC at 7.0C constant current;

[0128] Charge from 25% SOC to 30% SOC at 7.0C constant current;

[0129] Charge from 30% SOC to 35% SOC at 7.0C constant current;

[0130] Charge from 35% SOC to 40% SOC at 7.0C constant current;

[0131] Charge from 40% SOC to 45% SOC at 6.7C constant current;

[0132] Charge from 45% SOC to 50% SOC at 6.5C constant current;

[0133] Charge from 50% SOC to 55% SOC at 6.0C constant current;

[0134] Charge from 55% SOC to 60% SOC at 5.8C constant current;

[0135] Charge from 60% SOC to 65% SOC at 5.5C constant current;

[0136] Charge from 65% SOC to 70% SOC at 5.2C constant current;

[0137] Charge from 70% SOC to 75% SOC at 5.0C constant current;

[0138] Charge from 75% SOC to 80% SOC at 4.8C constant current.

[0139] In some embodiments, the charging time of the battery device or any battery cell 7 constituting the battery device from a 10% state of charge to an 80% state of charge is 5 min to 20 min, optionally less than or equal to 12 min, and further optionally 5 min to 8 min. The temperature of the external environment of the battery device at a 10% state of charge is room temperature, for example, 25° C. Exemplarily, the charging time of the battery device from a 10% state of charge to an 80% state of charge is 20 min, 19 min, 18 min, 17 min, 16 min, 15 min, 14.5 min, 14 min, 13.5 min, 13 min, 12.5 min, 12 min, 11.5 min, 11 min, 10.5 min, 10 min, 9.5 min, 9 min, 8.5 min, 8 min, 7.5 min, 7 min, 6.5 min, 6 min, 5 min, or a range consisting of any two of the above values.

[0140] like Figures 4 to 8As shown, the battery cell 7 includes an electrode assembly 10 and a housing assembly 20. The electrode assembly 10 includes a plurality of first pole sheets 11 and a plurality of second pole sheets 12. The first pole sheets 11 and the second pole sheets 12 are stacked along the thickness direction X of the battery cell 7. The first pole sheets 11 and the second pole sheets 12 each include a coating portion and a pole ear portion. The coating portion is provided with an active material layer. The pole ear portion is connected to the coating portion and extends out of the coating portion and is not coated with the active material layer. One of the first pole sheet 11 and the second pole sheet 12 is a positive pole sheet, and the other is a negative pole sheet. The active material layer of the positive pole sheet includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure.

[0141] The dimension of the coated portion of the positive electrode sheet along the length direction Z is a first dimension, the dimension of the coated portion of the positive electrode sheet along the width direction Y is a second dimension, and the ratio of the first dimension to the second dimension is 4 to 7;

[0142] The housing assembly 20 includes a housing and a terminal assembly. The housing accommodates the electrode assembly 10. The terminal assembly includes at least one first electrode terminal 31, which is connected to the pole ear portion of the first pole piece 11. The terminal assembly also includes at least one second electrode terminal 32, which is connected to the pole ear portion of the second pole piece.

[0143] in,

[0144] The battery cell meets the following requirements: (x1×S1+x2×S2) / E is 0.4 to 1.4,

[0145] x1 represents the number of first electrode terminals 31;

[0146] x2 represents the number of second electrode terminals 32;

[0147] S1 represents the minimum cross-sectional area of ​​a single first electrode terminal 31 perpendicular to its own thickness direction, and its unit is mm 2 ;

[0148] S2 represents the minimum cross-sectional area of ​​a single second electrode terminal 32 perpendicular to its own thickness direction, and its unit is mm 2 ;

[0149] E represents the single cell energy of the battery cell, and its unit is Wh.

[0150] Optionally, the electrode assembly 10 further includes an isolation member 13 , which is located between the first electrode piece 11 and the second electrode piece 12 .

[0151] The electrode assembly 10 has a laminated structure, with multiple first electrode sheets 11 and multiple second electrode sheets 12 stacked. Compared to a wound structure, the laminated structure does not have a bending zone, which makes it easier to increase the amount of active material coated on the laminated structure, so that the battery cell 7 has a relatively high energy density. In addition, in the embodiment of the present application, the ratio of the dimension of the coated portion of the positive electrode sheet along the length direction Z to the dimension of the coated portion of the positive electrode sheet along the width direction Y is 4 to 7. The relatively long length of the coated portion is conducive to carrying a relatively large amount of positive electrode active material, which is conducive to the battery cell 7 having a relatively high energy density and facilitating the battery cell 7 to store more single-cell energy.

[0152] When the coating portion is relatively long, the electron transmission path in the length direction is long, the internal resistance is relatively high, which is not conducive to fast charging. In addition, the positive electrode active material includes lithium-containing phosphate with relatively poor conductivity, which further increases the internal resistance of the positive electrode sheet.

[0153] In order to quickly store higher single-cell energy in the battery cell, the embodiment of the present application also improves the total flow capacity of all electrode terminals. x1×S1+x2×S2 can represent the total flow capacity of all electrode terminals in the battery cell 7. When (x1×S1+x2×S2) / E is greater than or equal to 0.4, the flow area of ​​the first electrode terminal 31 and the second electrode terminal 32 is relatively high, the flow capacity is relatively strong, the electrons can be quickly conducted, and it can also effectively reduce the internal resistance of the battery cell 7 and reduce the heat generation of the battery cell 7, thereby improving the fast charging capability of the battery cell 7, so that the battery cell quickly reaches the required capacity.

[0154] For example, the formula (x1×S1+x2×S2) / E performs only numerical calculations without units. (x1×S1+x2×S2) / E can be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or a range consisting of any two of the above values.

[0155] In the embodiment of the present application, the dimension of the battery cell 7 along its own length direction is the length of the battery cell 7 , the dimension of the battery cell 7 along its own width direction is the width of the battery cell 7 , and the dimension of the battery cell 7 along its own thickness direction is the thickness of the battery cell 7 . Figure 4 The X direction shown in FIG. 7 is the thickness direction of the battery cell 7 , the Y direction is the width direction of the battery cell 7 , and the Z direction is the length direction of the battery cell 7 .

[0156] In some embodiments, the ratio of the length of the battery cell 7 to the thickness of the battery cell 7 is 40 to 70, such as 40, 45, 50, 55, 60, 65, 70, or a range consisting of any two of the foregoing values. When the ratio of the length of the battery cell 7 to the thickness of the battery cell 7 is within the foregoing range, both the energy density and the fast charging performance of the battery cell can be improved.

[0157] In some embodiments, the ratio of the width of the battery cell 7 to the thickness of the battery cell 7 is 3 to 15, such as 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, or a range consisting of any two of the foregoing values. Optionally, the ratio of the width of the battery cell 7 to the thickness of the battery cell 7 is 4 to 12. When the ratio of the width of the battery cell 7 to the thickness of the battery cell 7 is within the above range, both the energy density and the fast charging performance of the battery cell can be improved.

[0158] In some embodiments, the thickness of the battery cell 7 is between 10 mm and 30 mm, such as 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, or a range consisting of any two of the foregoing values. The relatively thin thickness of the battery cell 7 facilitates rapid heat dissipation, reduces heat accumulation within the system, and facilitates rapid charging of the battery cell 7.

[0159] In the embodiment of the present application, the cell energy of the battery cell 7 can represent the electrical energy stored in the battery cell 7. E=U×Q, where U represents the rated voltage of the battery cell 7 in V and Q represents the rated capacity of the battery cell 7 in Ah.

[0160] The single cell energy of the battery cell 7 can be adjusted by the size of the battery cell, the size of the positive and negative electrode sheets, the material of the positive and negative electrode active materials, the single-sided coating weight of the positive and negative electrode film layers, the compaction density, etc.

[0161] For example, as the length of the battery cell 7 increases, the amount of active material that can be accommodated increases, the rated capacity of the battery cell 7 increases, and the single cell energy of the battery cell 7 can be improved;

[0162] For example, as the thickness of the battery cell 7 increases, the amount of active material that can be accommodated increases, the rated capacity of the battery cell 7 increases, and the single cell energy of the battery cell 7 can be improved;

[0163] For example, as the length of the positive electrode film layer of the positive electrode sheet increases, the amount of positive electrode active material that can be accommodated increases, the rated capacity of the battery cell 7 increases, and the single cell energy of the battery cell 7 can be improved;

[0164] For example, as the coating weight on one side of the positive electrode sheet increases, the rated capacity of the battery cell 7 increases, which can improve the single cell energy of the battery cell 7;

[0165] For example, as the compaction density of the positive electrode sheet increases, the rated capacity of the battery cell 7 increases, which can improve the single cell energy of the battery cell 7;

[0166] For example, if the positive electrode active material is adjusted and the rated voltage is adjusted from 3.65V to 3.8V, the single cell energy of the battery cell 7 will increase.

[0167] Similarly, the change trend of the monomer energy caused by the change of the relevant parameters of the negative electrode is similar to the change trend caused by the positive electrode, and will not be repeated here.

[0168] In some embodiments, the single cell energy E Wh of the battery cell 7 is 170Wh to 480Wh, such as 150Wh, 200Wh, 250Wh, 300Wh, 350Wh, 400Wh, 450Wh, 480Wh, or a range consisting of any two of the above values.

[0169] For example, the battery cell 7 uses lithium-containing phosphate as the positive electrode active material, and its rated voltage is 3.22V; when the rated capacity is 100Ah, the single cell energy of the battery cell 7 is 3.22V×100Ah=322Wh.

[0170] For a clearer description of the present application, the tab portion of the first pole piece 11 is defined as the first pole piece 111, and the coated portion of the first pole piece 11 is defined as the first coated portion 112. The tab portion of the second pole piece 12 is defined as the second pole piece 121, and the coated portion of the second pole piece 12 is defined as the second coated portion 122. The electrode terminal having the same electrical properties as and electrically connected to the first pole piece 111 is the first electrode terminal 31, and the electrode terminal having the same electrical properties as and electrically connected to the second pole piece 121 is the second electrode terminal 32.

[0171] The polarities of the first electrode piece 11 and the second electrode piece 12 are opposite. When the first electrode piece 11 is a positive electrode piece, the second electrode piece 12 is a negative electrode piece, the first electrode terminal 31 is a positive terminal, and the second electrode terminal 32 is a negative terminal; or when the first electrode piece 11 is a negative electrode piece, the second electrode piece 12 is a positive electrode piece, the first electrode terminal 31 is a negative terminal, and the second electrode terminal 32 is a positive terminal.

[0172] In an embodiment of the present application, optionally, the housing assembly 20 further includes a first conductive fixing member 41, which is arranged around the outside of the first electrode terminal 31. The outer contour of the first electrode terminal 31 can be circular, elliptical, runway-shaped, rectangular, etc. The first conductive fixing member 41 is arranged around the outer contour of the first electrode terminal 31.

[0173] [Casing components]

[0174] In some embodiments, the battery cell 7 further includes a housing assembly 20 having a housing space for accommodating the electrode assembly 10 and the electrolyte. The housing assembly 20 includes a housing and a terminal assembly, and the terminal assembly is disposed on the housing.

[0175] The outer shell can be made of steel, aluminum, plastic (e.g., polypropylene), a composite metal shell (e.g., a copper-aluminum composite shell), or an aluminum-plastic film. In some embodiments, the outer shell can be either sealed or non-sealed. For example, in a non-sealed outer shell, the outer shell protects the electrode assembly 10 and includes a sealed bag between the outer shell and the electrode assembly 10, which encapsulates the electrode assembly 10 and the electrolyte. Specifically, the sealed bag can be a bag-shaped insulating member or an aluminum-plastic film. In a sealed outer shell, the sealed bag encapsulates the electrode assembly 10 and other components, such as the electrolyte.

[0176] As an example, the battery cell 7 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, and a polygonal battery such as a hexagonal battery. There is no special limitation in this application.

[0177] In some embodiments, the housing includes an end cap 22 and a shell 21. The shell 21 has an opening, and the end cap 22 covers the opening. The shell 21 may have one or more openings. One or more end caps 22 may also be provided.

[0178] The terminal assembly can be provided on the housing 21, or the terminal assembly can be provided on the end cover 22. Optionally, the terminal assembly is provided on the end cover 22. When the terminal assembly is provided on the end cover 22, the thickness direction of the terminal assembly itself is perpendicular to the thickness direction X of the battery cell 7. Figure 8 The Z direction shown in is parallel to the thickness direction of the first electrode terminal 31 .

[0179] The first electrode terminal 31 and the second electrode terminal 32 may be provided on the housing 21 , or the first electrode terminal 31 and the second electrode terminal 32 may be provided on the end cover 22 . Alternatively, the first electrode terminal 31 and the second electrode terminal 32 may be provided on the end cover 22 .

[0180] The first electrode terminal 31 and the second electrode terminal 32 can be disposed on the same end cap 22. For example, there is one end cap 22, and the first electrode terminal 31 and the second electrode terminal 32 are disposed on the end cap 22 at intervals. In another example, there are two end caps 22, and the two end caps 22 are disposed opposite each other, and each end cap 22 is provided with a first electrode terminal 31 and a second electrode terminal 32.

[0181] The first electrode terminal 31 and the second electrode terminal 32 are respectively provided on different end covers 22 . For example, there are two end covers 22 , which are arranged opposite to each other. The first electrode terminal 31 is provided on one of the end covers 22 , and the second electrode terminal 32 is provided on the other end cover 22 .

[0182] The shape of the housing 21 can be determined based on the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, a cylindrical housing 21 can be selected; if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped housing 21 can be selected. Optionally, both the electrode assembly 10 and the housing 21 have rectangular parallelepiped structures.

[0183] In some embodiments, the battery cell 7 satisfies: x1×S1 / E is 0.2 to 0.7,

[0184] S1 represents the minimum cross-sectional area of ​​a single first electrode terminal 31 perpendicular to its own thickness direction, and its unit is mm 2 .

[0185] x1×S1 represents the minimum cross-sectional area of ​​all first electrode terminals 31 perpendicular to their own thickness direction, and its unit is mm 2 .

[0186] For example, x1×S1 / E, this formula only performs numerical calculations without units, and x1×S1 / E is 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, or a range consisting of any two of the above values.

[0187] x1×S1 / E is greater than or equal to 0.2, the first electrode terminal has a strong current carrying capacity, and can also effectively reduce the internal resistance of the battery cell 7, reduce the heat generation of the battery cell 7, and improve the fast charging capability of the battery cell 7, so that the battery cell 7 can quickly reach the required capacity.

[0188] In some embodiments, S1 mm 2 15mm 2 Up to 60mm 2 For example, 15mm², 30mm², 35mm², 40mm², 45mm², 50mm², 55mm², 60mm², or a range consisting of any two of the above values. When the flow area of ​​the first electrode terminal 31 is within the above range, its flow capacity is strong, which can improve the fast charging capability of the battery cell.

[0189] In some embodiments, x1 is 1 to 4, for example, 1, 2, 3, or 4. As the number of first electrode terminals 31 increases, the current capacity of all first electrode terminals 31 increases, thereby improving the fast charging capability of the battery cells.

[0190] The portion of the first electrode terminal 31 connected to the first conductive fixing member 41 is a solid structure with a preset height. Along the thickness direction of the first electrode terminal 31, the cross-sectional sizes of the first electrode terminal 31 perpendicular to its own thickness direction can be the same or different. When the cross-sectional sizes of the first electrode terminal 31 perpendicular to its own thickness direction are different, the smallest area is defined as the minimum cross-sectional area. Figure 8 J1 shown in FIG. 1 is the cross section where the minimum cross-sectional area is located, and its area is S1.

[0191] The outer contour of the minimum cross-sectional area is the minimum contour of the connection between the first electrode terminal 31 and the first conductive fixing member 41, and is the bottleneck of current transmission between the first electrode terminal 31 and the first conductive fixing member 41; and in the embodiment of the present application, x1×S1 / E is 0.2 to 0.7, so that the current flow capacity of the first electrode terminal 31 is relatively strong, which can effectively reduce the internal resistance of the battery cell 7 and reduce the heat generation of the battery cell 7. In addition, the thickness of the battery cell 7 is relatively thin, which is conducive to the rapid heat dissipation of the battery cell 7, thereby improving the fast charging capability of the battery cell 7.

[0192] In some embodiments, there is at least one, and optionally at least two, first electrode terminals 31. For example, x1 is any positive integer from 1 to 4. x1×S1 can represent the overcurrent capacity of all first electrode terminals 31 in the battery cell 7.

[0193] In some embodiments, the first electrode terminal 31 may include a first main portion 312 and a first protrusion 311. The first main portion 312 is disposed on and passes through the end cap 22. The first protrusion 311 is disposed on the first main portion 312 and protrudes from the first main portion 312 to connect to the side of the end cap 22 facing the electrode assembly 10. It can be understood that the first protrusion 311 is disposed around the outside of the first main portion 312 and is connected to the side of the end cap 22 facing the electrode assembly 10. Optionally, the first conductive fixing member 41 is disposed around the outside of the first main portion 312.

[0194] In other embodiments, the first electrode terminal 31 may include only the first main body 312 , which passes through the end cap 22 and is connected to the electrode tab. Optionally, the first conductive fixing member 41 is disposed around the first main body 312 .

[0195] In the embodiment of the present application, the first electrode terminal 31 may be an integrated structure, may be integrally formed, or may be connected to form an integrated structure by welding or other means. The integrated structure is beneficial for reducing resistance and heat generation.

[0196] Optionally, the dimension of the first protrusion 311 is 1.5 mm to 3.0 mm in the direction from the first main portion 312 to the first protrusion 311. When the first electrode terminal 31 is disposed on the end cap 22 of the housing, the direction from the first main portion 312 to the first protrusion 311 can be parallel to the width direction Y of the battery cell 7. In this case, the dimension of the first protrusion 311 along the width direction Y is 1.5 mm to 3.0 mm. Figure 8 T1 shown in FIG. 3 represents the dimension of the first protrusion 311 along the width direction Y.

[0197] When the first protrusion 311 meets the above conditions, the connection area between the first protrusion 311 and the housing is relatively larger, the connection strength is higher, and the structure makes the battery cell 7 more stable.

[0198] Optionally, the ratio of the dimension of the first main body 312 along the thickness direction X of the battery cell 7 to the dimension of the end cover 22 along the thickness direction X of the battery cell 7 is 0.20 to 0.40, for example, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, 0.40 or a range consisting of any two of the above values; the dimension of the first main body 312 refers to the dimension of the first main body 312 of a single first electrode terminal 31. Figure 7 X3 shown in the figure represents the dimension of the first main body 312 of a single first electrode terminal 31 along the thickness direction X, which can be understood as the width of the first main body 312; X2 represents the dimension of the end cover 22 along the thickness direction X, which can be understood as the width of the end cover 22.

[0199] When the first main body portion 312 meets the above conditions, the size of the first main body portion 312 is relatively high, which is beneficial to improving the current capacity of the first electrode terminal 31 and thus improving the fast charging performance.

[0200] The housing assembly 20 also includes a first conductive fixing member 41, at least part of which is located on the side of the end cover 22 facing away from the electrode assembly, and is used to connect to the external bus assembly. The first conductive fixing member 41 is arranged around the outside of the first electrode terminal 31 and fixedly connects the first electrode terminal 31 and the end cover 22.

[0201] The first conductive fixing member 41 can further increase the flow area between the battery cell 7 and the external bus assembly, thereby improving the flow capacity, which is beneficial to improving the flow capacity of the battery device and improving the fast charging performance of the battery device.

[0202] Optionally, a portion of the first main body portion 312 protrudes from a side of the end cover 22 facing away from the electrode assembly 10 , and the first conductive fixing member 41 is disposed around the outside of the first main body portion 312 .

[0203] Optionally, the ratio of the dimension of the first conductive fixing member 41 along the thickness direction X of the battery cell 7 to the dimension of the end cap 22 along the thickness direction X of the battery cell 7 is 0.40 to 0.80, for example, 0.40, 0.42, 0.44, 0.46, 0.48, 0.50, 0.52, 0.54, 0.56, 0.58, 0.60, 0.62, 0.64, 0.66, 0.68, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80, or a range consisting of any two of the foregoing values. The dimension of the first conductive fixing member 41 refers to the dimension of a single first conductive fixing member 41. Figure 7 X1 shown in the figure represents the dimension of the first conductive fixing member 41 along the thickness direction X, which can be understood as the width of the first conductive fixing member 41.

[0204] When the first conductive fixing member 41 meets the above conditions, the size of the first conductive fixing member 41 is relatively high, which is beneficial to increasing the flow area between the battery cell 7 and the external bus assembly, thereby improving the flow capacity, which is beneficial to improving the flow capacity of the battery device and improving the fast charging performance of the battery device.

[0205] like Figure 9 As shown, in some embodiments, the terminal assembly further includes at least one second electrode terminal 32, and the second electrode terminal 32 is connected to the pole ear portion of the second pole piece.

[0206] Battery cell 7 satisfies: x2×S2 / E is 0.2 to 0.7,

[0207] S2 represents the minimum cross-sectional area of ​​a single second electrode terminal 32 perpendicular to its own thickness direction, and its unit is mm 2 .

[0208] x2×S2 represents the minimum cross-sectional area of ​​all second electrode terminals 32 perpendicular to their own thickness direction, and its unit is mm 2 .

[0209] In the embodiment of the present application, x2×S2 / E is 0.2 to 0.7, so that the current flow capacity of the second electrode terminal 32 is relatively strong, which can effectively reduce the internal resistance of the battery cell 7, reduce the heat generation of the battery cell 7, and improve the fast charging capability of the battery cell 7.

[0210] In some embodiments, S2mm 2 15mm 2 Up to 60mm 2For example, 15mm², 30mm², 35mm², 40mm², 45mm², 50mm², 55mm², 60mm², or a range consisting of any two of the above values. When the flow area of ​​the second electrode terminal 32 is within the above range, its flow capacity is strong, which can improve the fast charging capability of the battery cell.

[0211] In some embodiments, x2 is 1 to 4, such as 1, 2, 3, or 4. As the number of second electrode terminals 32 increases, the current capacity of all second electrode terminals 32 is enhanced, which can improve the fast charging capability of the battery cells.

[0212] The portion of the second electrode terminal 32 connected to the second conductive fixing member is a solid structure with a preset height. Along the thickness direction of the second electrode terminal 32, the cross-sectional sizes of the second electrode terminal 32 perpendicular to its own thickness direction can be the same or different; when the cross-sectional sizes of the second electrode terminal 32 perpendicular to its own thickness direction are different, the smallest area is defined as the minimum cross-sectional area.

[0213] The outer contour of the minimum cross-sectional area is the minimum contour of the connection between the second electrode terminal 32 and the second conductive fixing member, and is the bottleneck of current transmission between the second electrode terminal 32 and the second conductive fixing member; and in the embodiment of the present application, x2×S2 / E is 0.2 to 0.7, so that the second electrode terminal 32 has a relatively strong current flow capacity, which can effectively reduce the internal resistance of the battery cell 7 and reduce the heat generation of the battery cell 7, thereby improving the fast charging capability of the battery cell 7.

[0214] For example, x2×S2 / E, this formula only performs numerical calculations without units, and x2×S2 / E is 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7 or a range consisting of any two of the above values.

[0215] In some embodiments, there is at least one, and optionally at least two, second electrode terminals 32. For example, x2 is any positive integer from 1 to 4. x2×S2 can represent the overcurrent capacity of all second electrode terminals 32 in the battery cell 7.

[0216] In some embodiments, the structure of the second electrode terminal 32 is similar to that of the first electrode terminal 31. For example, the second electrode terminal 32 may include a second main body portion and a second protruding portion. The second main body portion extends through the housing, and the second conductive fixing member is disposed around the second main body portion. The second protruding portion is disposed on the second main body portion, protruding from the second main body portion and connected to the side of the housing facing the electrode assembly 10. In other embodiments, the second electrode terminal 32 may include only the second main body portion, which extends through the end cap 22 and is connected to the electrode tab portion.

[0217] Optionally, the dimension of the second protrusion is 1.5 mm to 3.0 mm in the direction from the second main body to the second protrusion. When the second electrode terminal 32 is provided on the end cap 22, the direction from the second main body to the second protrusion can be parallel to the width direction Y of the battery cell 7. In this case, the dimension of the second protrusion along the width direction Y is 1.5 mm to 3.0 mm.

[0218] When the second protrusion meets the above conditions, the connection area between the second protrusion and the shell is relatively larger, the connection strength is higher, and the structure makes the battery cell 7 more stable.

[0219] Optionally, the ratio of the size of the second main body along the thickness direction X of the battery cell 7 to the size of the end cover 22 along the thickness direction X of the battery cell 7 is 0.20 to 0.40, for example, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, 0.40 or a range consisting of any two of the above values; in this embodiment of the application, the size of the second main body refers to the size of the second main body of a single second electrode terminal 32.

[0220] When the second main body meets the above conditions, the size of the second main body is relatively high, which is beneficial to improving the current capacity of the second electrode terminal 32, thereby improving the fast charging performance.

[0221] The housing assembly 20 further includes a second conductive fixing member, which is disposed around the second electrode terminal 32 and fixedly connects the second electrode terminal 32 and the end cap 22 .

[0222] The second conductive fixing member can further increase the flow area between the battery cell 7 and the external bus assembly, thereby improving the flow capacity, which is beneficial to improving the flow capacity of the battery device and improving the fast charging performance of the battery device.

[0223] Optionally, a portion of the second main body protrudes from a side of the end cover 22 away from the electrode assembly 10 , and the second conductive fixing member is disposed around the outside of the second main body.

[0224] Optionally, the ratio of the dimension of the second conductive fixing member along the thickness direction X to the dimension of the end cover 22 along the thickness direction X is 0.40 to 0.80, for example, 0.40, 0.42, 0.44, 0.46, 0.48, 0.50, 0.52, 0.54, 0.56, 0.58, 0.60, 0.62, 0.64, 0.66, 0.68, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80 or a range consisting of any two of the above values; in this embodiment of the application, the thickness direction X refers to the thickness direction X of the battery cell 7.

[0225] When the second conductive fixing member meets the above conditions, the size of the second conductive fixing member is relatively high, which is beneficial to increasing the flow area between the battery cell 7 and the external bus assembly, thereby improving the flow capacity, which is beneficial to improving the flow capacity of the battery device and improving the fast charging performance of the battery device.

[0226] like Figure 10 As shown, in some embodiments, at least one first electrode terminal 31 is arranged on at least one side of the electrode assembly 10 along the width direction Y. This arrangement can shorten the migration path of electrons and is conducive to improving the fast charging performance.

[0227] For example, all the first electrode terminals 31 are disposed on one side of the electrode assembly 10 along the width direction Y.

[0228] For another example, the plurality of first electrode terminals 31 are disposed on both sides of the electrode assembly 10 along the width direction Y.

[0229] like Figure 11 As shown, in some embodiments, at least one first electrode terminal 31 is disposed on at least one side of the electrode assembly 10 along the length direction Z.

[0230] For example, all the first electrode terminals 31 are disposed on one side of the electrode assembly 10 along the length direction Z.

[0231] For another example, a plurality of first electrode terminals 31 are respectively arranged on both sides of the electrode assembly 10 along the length direction Z. This arrangement can shorten the migration path of electrons and is conducive to improving the fast charging performance.

[0232] Exemplarily, there are two first electrode terminals 31, one of which is disposed on one side of the electrode assembly 10, and the other first electrode terminal 31 is disposed on the other side of the electrode assembly 10. Alternatively, exemplary, there are four first electrode terminals 31, two of which are disposed on one side of the electrode assembly 10, and the other two first electrode terminals 31 are disposed on both sides of the electrode assembly 10.

[0233] The first electrode tab 111 and the first electrode terminal 31 are electrically connected, which can be directly or indirectly connected; when the first electrode tab 111 and the first electrode terminal 31 are indirectly connected, the battery cell 7 may include a first adapter 51, which is located between the first electrode terminal 31 and the first electrode tab 111 and connects the first electrode terminal 31 and the first electrode tab 111.

[0234] For example, when the first electrode terminal 31 is arranged on at least one side of the electrode assembly 10 along the length direction Z, and the first electrode tab 111 is arranged on at least one side of the first coating portion 112 along the width direction Y, the first adapter 51 is more conducive to the connection between the first electrode tab 111 and the first electrode terminal 31.

[0235] When the first pole tab 111 and the first electrode terminal 31 are respectively arranged on different sides of the battery cell 7, the first adapter 51 may include a first adapter portion 511 and a second adapter portion 512, the first adapter portion 511 extends along the length direction Z, the first adapter portion 511 is connected to the first pole tab 111, the second adapter portion 512 is connected to the first adapter portion 511 and protrudes from the first adapter portion 511 along the width direction Y, and is connected to the first electrode terminal 31.

[0236] In the case where the first electrode tab 111 and the first electrode terminal 31 are disposed on the same side of the battery cell 7 , the first adapter 51 may only include the first adapter portion 511 .

[0237] In the above embodiments, the first adapter 51 may be a sheet-like structure, and may also be other structural forms.

[0238] In the above embodiments, the first adapter 51 may include a conductive polymer or a conductive metal material. The conductive metal material may include copper, aluminum, or an alloy containing the above metal elements.

[0239] In some embodiments, the battery cell 7 further includes a first conductive member 61, which is located between the first adapter 51 and the first pole tab 111. The setting of the first conductive member 61 can increase the current flow capacity between the first pole tab 111 and the first adapter 51, which is beneficial to improving the fast charging performance and reducing heat generation.

[0240] For example, the tab portion of the first electrode piece 11 is disposed on one side of the coating portion along the width direction Y; the first conductive member 61 is located between the first adapter 51 and the first tab 111 , and connects the first adapter 51 and the first tab 111 .

[0241] Optionally, there are at least two first pole tabs 111 and at least two first conductive members 61 . The first conductive members 61 and the first pole tabs 111 are connected one-to-one, and at least two first conductive members 61 are connected to the first adapter 51 . This connection method is beneficial to improving the weight energy density of the battery cell 7 .

[0242] Optionally, there are at least two first electrode tabs 111 located on the same side of the first coating portion 112 , and the first conductive member 61 may be a continuous sheet structure connecting the at least two first electrode tabs 111 .

[0243] like Figure 12 As shown, when the first tab 111 and the first electrode terminal 31 are respectively arranged on different sides of the battery cell 7, the first conductive member 61 optionally includes a first conductive portion 611 and a second conductive portion 612. The first conductive portion 611 extends along the length direction Z and connects the first tab 111 and the first adapter 51. The second conductive portion 612 is connected to the first conductive portion 611 and protrudes from the first conductive portion 611 along the width direction Y. The second conductive portion 612 is connected to the first conductive portion 611. This structural arrangement is conducive to increasing the grouping space in the length direction Z and improving the energy density of the battery device.

[0244] It should be noted that, when the battery cell 7 does not include the first adapter 51 , the first electrode tab 111 may be connected to the first electrode terminal 31 through the first conductive member 61 .

[0245] Exemplarily, the first conductive member 61 has electrical conductivity, and may include a conductive polymer or a conductive metal material. The conductive metal material may include copper, aluminum, or an alloy containing the above metal elements.

[0246] In some embodiments, at least one second electrode terminal 32 is disposed on at least one side of the electrode assembly 10 along the width direction Y. This arrangement can shorten the migration path of electrons and is conducive to improving fast charging performance.

[0247] For example, all the second electrode terminals 32 are arranged on one side of the electrode assembly 10 along the width direction Y. In this case, the first electrode terminal 31 and the second electrode terminal 32 can be respectively arranged on both sides of the electrode assembly 10 along the width direction Y, and will not interfere with each other when they are electrically connected to the electrode ear parts.

[0248] Exemplarily, there are two first electrode terminals 31 and two second electrode terminals 32 . The two first electrode terminals 31 are arranged on one side of the electrode assembly 10 along the width direction Y, and the two second electrode terminals 32 are arranged on the other side of the electrode assembly 10 along the width direction Y.

[0249] For another example, multiple second electrode terminals 32 are disposed on both sides of the electrode assembly 10 along the width direction Y. This arrangement can further shorten the electron migration path, which is beneficial for improving fast charging performance. In this case, the first electrode terminal 31 and the second electrode terminal 32 are disposed on one side of the electrode assembly 10 along the width direction Y, and the first electrode terminal 31 and the second electrode terminal 32 are disposed on the other side of the electrode assembly 10 along the width direction Y.

[0250] In some embodiments, at least one second electrode terminal 32 is disposed on at least one side of the electrode assembly 10 along the length direction Z.

[0251] For example, at least two second electrode terminals 32 are respectively provided on both sides of the electrode assembly 10 along the length direction Z. This arrangement can shorten the electron migration path and improve the fast charging performance. In this case, the first electrode terminal 31 and the second electrode terminal 32 are provided on one side of the electrode assembly 10 along the length direction Z, and the first electrode terminal 31 and the second electrode terminal 32 are provided on the other side of the electrode assembly 10 along the length direction Z.

[0252] Illustratively, there are two second electrode terminals 32 , one of which is disposed on one side of the electrode assembly 10 along the length direction Z, and the other second electrode terminal 32 is disposed on the other side of the electrode assembly 10 along the length direction Z. There are two first electrode terminals 31 , one of which is disposed on one side of the electrode assembly 10 , and the other first electrode terminal 31 is disposed on both sides of the electrode assembly 10 . Figure 12 A schematic diagram showing four electrode terminals is shown.

[0253] For another example, all the second electrode terminals 32 are arranged on one side of the electrode assembly 10 along the length direction Z. In this case, the first electrode terminal 31 and the second electrode terminal 32 can be respectively arranged on both sides of the electrode assembly 10 along the length direction Z, and will not interfere with each other when they are electrically connected to the electrode ear parts.

[0254] Exemplarily, there is one first electrode terminal 31 and one second electrode terminal 32, each located on either side of the electrode assembly along the length direction Z. The first electrode terminal 31 and the second electrode terminal 32 are staggered along the width direction Y. Specifically, when all second electrode tabs 121 are located on the same side of the second coating portion 122 along the width direction Y, and all first electrode tabs 111 are located on the same side of the first coating portion 112 along the width direction Y, the first electrode tab 111 and the second electrode tab 121 are located on either side of the coating portion along the width direction Y, with the first electrode terminal 31 positioned proximate to the first electrode tab 111 and the second electrode terminal 32 positioned proximate to the second electrode tab 121. This arrangement shortens the electron transmission distance and is more conducive to improving the fast charging capability of the battery cell 7. Figure 11 A schematic diagram showing two electrode terminals is shown.

[0255] The second electrode tab 121 is electrically connected to the second electrode terminal 32 , which may be directly or indirectly connected. When the second electrode tab 121 is indirectly connected to the second electrode terminal 32 , the battery cell 7 may include a second adapter, which is located between the second electrode terminal 32 and the second electrode tab 121 and connects the second electrode terminal 32 and the second electrode tab 121 .

[0256] For example, when the second electrode terminal 32 is arranged on at least one side of the electrode assembly 10 along the length direction Z, and the second electrode tab 121 is arranged on at least one side of the second coating portion 122 along the width direction Y, the second adapter is more conducive to the connection between the second electrode tab 121 and the second electrode terminal 32.

[0257] When the second pole lug 121 and the second electrode terminal 32 are respectively arranged on different sides of the battery cell 7, the second adapter may include a first connecting portion and a second connecting portion, the first connecting portion extending along the length direction Z, the first connecting portion connected to the second pole lug 121, the second connecting portion connected to the first connecting portion and protruding from the first connecting portion along the width direction Y, and connected to the second electrode terminal 32.

[0258] In the case where the second electrode tab 121 and the second electrode terminal 32 are disposed on the same side of the battery cell 7 , the second adapter may include only the first connecting portion.

[0259] In the above embodiments, the second adapter may be a sheet-like structure, and may also be other structural forms.

[0260] In the above embodiments, the second transition component may include a conductive polymer or a conductive metal material. The conductive metal material may include copper, aluminum, or an alloy containing the above metal elements.

[0261] In some embodiments, the battery cell 7 further includes a second conductive member, which is located between the second adapter and the second pole tab 121. The provision of the second conductive member can increase the current flow capacity between the second pole tab 121 and the second adapter, which is beneficial to improving the fast charging performance and reducing heat generation.

[0262] For example, the pole tab portion of the second pole piece 12 is arranged on one side of the coating portion along the width direction Y; the second conductive member is located between the second adapter and the second pole tab 121 and connects the second adapter and the second pole tab 121 .

[0263] Optionally, there are at least two second pole ears 121 located on the same side of the second coating portion 122, and the second conductive member can be a continuous sheet structure, connecting at least two second pole ears 121; or there are at least two second conductive members, the second conductive members and the second pole ears 121 are connected one-to-one, and at least two second conductive members are connected to the second adapter. This connection method is beneficial to improving the weight energy density of the battery cell 7.

[0264] When the second electrode tab 121 and the second electrode terminal 32 are respectively arranged on different sides of the battery cell 7, the second conductive member can optionally include a third conductive portion and a fourth conductive portion. The third conductive portion extends along the length direction Z and connects the electrode tab of the second electrode sheet 12 to the second adapter. The fourth conductive portion is connected to the third conductive portion and protrudes from the third conductive portion along the width direction Y. The third conductive portion is connected to the second adapter. This structural arrangement is conducive to increasing the grouping space in the length direction Z and improving the energy density of the battery device.

[0265] Exemplarily, the second conductive member has electrical conductivity, and may include a conductive polymer or a conductive metal material. The conductive metal material may include copper, aluminum, or an alloy containing the above metal elements.

[0266] It should be noted that, when the battery cell 7 does not include the second adapter, the second electrode tab 121 may be connected to the second electrode terminal 32 via the second conductive member.

[0267] In some embodiments, the housing 21 includes two first shell portions 211, a second shell portion 212, and a third shell portion 213. The two first shell portions 211 are opposite to each other along the thickness direction X of the battery cell 7, the second shell portion 212 and the third shell portion 213 are opposite to each other, and the second shell portion 212 and the third shell portion 213 are connected by the first shell portion 211. The second shell portion 212 includes a first wall 2121 and a second wall 2122 continuously arranged along the thickness direction X, and the first wall 2121 and the second wall 2122 are welded. The first wall 2121 and the second wall 2122 can be welded by tailor welding, laser welding, etc., and tailor welding can be selected. Since the area of ​​the second shell portion 212 is relatively small and the degree of expansion is relatively small, the weld is located on the second shell portion 212, which can reduce the risk of leakage of the battery cell 7.

[0268] When the battery cell 7 is assembled into the battery device's housing, it is placed within the housing, which includes a first housing portion and a second housing portion, with the first housing portion covering the second housing portion. The second housing portion 212 is positioned opposite the first housing portion, with the second housing portion 212 positioned adjacent to the first housing portion, and the third housing portion 213 positioned adjacent to the second housing portion. When the battery device is assembled into an electrical device, the first housing portion can be vertically positioned above the second housing portion. The second housing portion 212 has a weld seam, which faces upward, reducing the risk of leakage from the battery cell 7.

[0269] In some embodiments, the dimension of the battery cell 7 along the thickness direction X is 10 mm to 30 mm, for example, 10 mm, 12 mm, 14 mm, 15 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 25 mm, 26 mm, 28 mm, 30 mm, or a range consisting of any two of the above values.

[0270] When the thickness of the battery cell 7 is within the above range, the thickness of the battery cell 7 is relatively small, which is conducive to rapid heat dissipation inside the battery cell 7 and reduces the risk of thermal runaway.

[0271] In some embodiments, the thickness of the housing 21 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.30 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm, 0.40 mm, 0.41 mm, 0.42 mm, 0.43 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.47 mm, 0.48 mm, 0.49 mm, 0.50 mm, 0.51 mm, 0.52 mm, 0.53 mm, 0.54 mm, 0.55 mm, 0.56 mm, 0.57 mm, 0.58 mm, 0.59 mm, 0.60 mm, 0.61 mm, 0.62 mm, 0.63 mm, 0.64 mm, 0.65 mm, 0.66 mm, 0.67 mm, 0.68 mm, 0.69 mm, 0.70 mm, 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or a range consisting of any two of the above values. Optionally, the thickness of the housing 21 is 0.3mm to 0.4mm.

[0272] When the thickness of the shell 21 is within the above range, the shell 21 is relatively thin, which is conducive to rapid heat dissipation of the shell 21.

[0273] Exemplarily, the thickness of the first shell portion 211 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0. 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or a range consisting of any two of the above values. Optionally, the thickness of the housing 21 is 0.3mm to 0.4mm.

[0274] Exemplarily, the thickness of the second shell portion 212 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0. 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or a range consisting of any two of the above values. Optionally, the thickness of the housing 21 is 0.3mm to 0.4mm.

[0275] Exemplarily, the thickness of the third shell portion 213 is 0.1 mm to 0.5 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0. 3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, or a range consisting of any two of the above values. Optionally, the thickness of the housing 21 is 0.3mm to 0.4mm.

[0276] Heat conduction components

[0277] In some embodiments, the battery cell 7 further includes a heat conduction component, and there is a gap between the pole ear portion and the coating portion. The heat conduction component is arranged in the gap between the pole ear portion and the coating portion. The heat conduction component can conduct the heat generated by the pole ear portion, quickly transfer the heat generated by the pole ear portion, and reduce the risk of heat erosion of the isolation member in the electrode assembly.

[0278] Optionally, the heat conduction member is further in contact with the housing 21 , so as to diffuse heat from the housing 21 .

[0279] like Figure 13As shown, exemplarily, the heat conducting member includes a first heat conducting member 81 , which is disposed in a gap between the first electrode tab 111 and the first coating portion 112 . The first heat conducting member 81 can conduct heat generated by the first electrode tab 111 .

[0280] Optionally, the first heat conduction member 81 may be further arranged in the gap between the first pole tab 111 and the first electrode terminal 31. When the battery cell 7 includes a first adapter 51, the first heat conduction member 81 may also be arranged in the gap between the first pole tab 111 and the first adapter 51, or in the gap between the second adapter portion 512 and the coating portion of the first adapter 51.

[0281] Exemplarily, the heat conducting member includes a second heat conducting member, which is disposed in a gap between the second electrode tab 121 and the second coating portion 122 , and can conduct heat generated by the second electrode tab 121 .

[0282] Optionally, the second heat conduction member may be further disposed in the gap between the second electrode tab 121 and the second electrode terminal 32 . When the battery cell 7 includes a second adapter, the second heat conduction member may be further disposed in the gap between the second electrode tab 121 and the second adapter.

[0283] The main material of the heat conduction component includes one or more of polyimide PI and polyethylene terephthalate PET.

[0284] [First pole piece and second pole piece]

[0285] In some embodiments, the battery cell 7 further satisfies: M1 / E is 0.2 to 0.6,

[0286] M1 represents the area of ​​the first connecting area, and its unit is mm 2 The first connection area is the area of ​​at least one first electrode terminal 31 connected to the tab portion of the first electrode sheet, i.e., the sum of the areas of all first electrode terminals 31 connected to the first tab 111. When welding is employed, M1 may represent the weld footprint of the first electrode terminal 31, which is the weld area between the first electrode terminal 31 and the first tab 111.

[0287] When the battery cell 7 meets the above conditions, the current conduction capability between the first electrode terminal 31 and the first electrode tab 111 is relatively strong, which is beneficial to reducing the internal resistance of the battery cell 7 and reducing the heat generation of the battery cell 7, thereby improving the fast charging capability of the battery cell 7.

[0288] In some embodiments, M1mm 2 60mm 2 Up to 120mm2 , such as 60mm², 70mm², 80mm², 90mm², 100mm², 110mm², 120mm², or a range consisting of any two of the above values. The first electrode terminal 31 and the first tab 111 have strong current conductivity, which helps to reduce the internal resistance of the battery cell 7 and reduce the heat generated by the battery cell 7, thereby improving the fast charging capability of the battery cell 7, allowing the battery cell 7 to quickly reach the required capacity.

[0289] In some embodiments, the battery cell 7 further satisfies: M2 / E is 0.2 to 0.6,

[0290] M2 represents the area of ​​the second connecting area, and its unit is mm 2 The second connection area is the area where at least one second electrode terminal 32 is connected to the pole ear portion of the second pole piece, that is, the sum of the areas where all second electrode terminals 32 are connected to the second pole ear 121.

[0291] When the battery cell 7 meets the above conditions, the current conduction capability between the second electrode terminal 32 and the second electrode tab 121 is relatively strong, which is beneficial to reducing the internal resistance of the battery cell 7 and reducing the heat generation of the battery cell 7, thereby improving the fast charging capability of the battery cell 7, so that the battery cell 7 can quickly reach the required capacity.

[0292] In some embodiments, M2mm 2 60mm 2 Up to 120mm 2 , such as 60mm², 70mm², 80mm², 90mm², 100mm², 110mm², 120mm², or a range consisting of any two of the above values. The second electrode terminal 32 and the second tab 121 have strong current conductivity, which helps reduce the internal resistance of the battery cell 7 and reduces the heat generated by the battery cell 7, thereby improving the fast charging capability of the battery cell 7.

[0293] In some embodiments, the first electrode tab 111 is disposed on at least one side of the first coating portion 112 along the first direction.

[0294] like Figure 14 and Figure 15 As shown, in some embodiments, the first pole piece 11 satisfies: n*W1 / W2 is 0.5 to 1.0;

[0295] n represents the number of all the tabs on the same side of the coating portion;

[0296] W1 represents the average size of the pole ear along the second direction, and the first direction is perpendicular to the second direction;

[0297] W2 represents the dimension of the coating portion along the second direction.

[0298] Illustratively, n*W1 / W2 is 0.5, 0.55, 0.6, 2 / 3, 0.7, 0.75, 0.8, 0.85, 0.9, 1.0, or a range consisting of any two of the above values.

[0299] In the embodiment of the present application, the first pole piece 11 also satisfies n*W1 / W2 of 0.5 to 1.0, so that the connection area between the pole ear and the coating portion is relatively large, and the flow area of ​​the pole ear is relatively large, which is beneficial to reducing DC resistance and reducing heat generation; there are at least two first electrode terminals 31, in other words, at least two first electrode terminals 31 are connected to the pole ear of the first pole piece 11, which can further increase the flow area of ​​the first electrode terminal 31 and the pole ear, further reduce DC resistance, reduce heat generation, and thus facilitate fast charging.

[0300] W1 represents the average size of the first electrode tab 111 along the second direction,

[0301] When the first electrode tab 111 has a special-shaped structure, for example, the size of the first electrode tab 111 along the second direction gradually increases along the first direction, in this case, the size of the first electrode tab 111 along the second direction at multiple locations can be measured to calculate the average size of the first electrode tab 111 along the second direction. Of course, the size of each location of the first electrode tab 111 along the second direction can be the same value, in which case this value can be used as the average size of the first electrode tab 111.

[0302] There may be one or more first pole tabs 111 , for example, n is 1 to 4. In the case of multiple first pole tabs 111 , the average size of each first pole tab 111 may be measured separately, and the sum of the average size values ​​may be divided by the number of first pole tabs 111 to calculate the average size of the first pole tabs 111 .

[0303] The first pole tab 111 is connected to the first coating portion 112, and the first pole tab 111 includes a first end 1111 connected to the first coating portion 112. When n*W1 / W2 satisfies the above range, it means that the cross-section of the first end 1111 along the thickness direction of the first pole tab 111 itself is relatively large, the contact area between the first pole tab 111 and the first coating portion 112 is relatively large, and the first pole tab 111 has a strong current-carrying capacity, which can improve the power performance and cycle performance of the battery cell 7.

[0304] Optionally, the first electrode tab 111 and the current collecting portion of the first coating portion 112 are an integrated structure, so that the internal resistance of the first electrode sheet 11 is low, which can further improve the power performance and cycle performance of the battery cell 7 .

[0305] Optionally, W2 is 300 mm to 650 mm, for example, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm or a range consisting of any two of the above values.

[0306] Optionally, n*W1 is 150 mm to 650 mm, for example, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm or a range consisting of any two of the above values.

[0307] In the embodiment of the present application, the first direction, the second direction and the thickness direction X of the battery cell 7 are perpendicular to each other. The first direction can be parallel to the length direction of the battery cell 7 or parallel to the width direction of the battery cell 7.

[0308] When the first direction is parallel to the length direction Z of the battery cell 7, the dimension of the component in this direction can be considered as the length of the component. For example, the dimension of the coating portion along the first direction is the length of the coating portion. In this case, the second direction is parallel to the width direction Y of the battery cell 7.

[0309] When the first direction is parallel to the width direction Y of the battery cell 7, the dimension of the component in this direction can be considered as the width of the component. For example, the dimension of the coating portion along the first direction is the width of the coating portion. In this case, the second direction is parallel to the length of the battery cell 7.

[0310] Figure 14 and Figure 15 , it is shown that the first direction is parallel to the width direction Y, and the second direction is parallel to the length direction Z. Figure 14 In , n is 1, W1 may also represent the size of a single first electrode tab 111 , and W2 represents the size of the first coating portion 112 along the second direction. Figure 15 In FIG, n is 4, and the sizes of the first electrode tabs 111 are the same. W1 may represent the size of a single first electrode tab 111 . Of course, the sizes of the first electrode tabs 111 may also be slightly different.

[0311] When the first electrode sheet 11 is a positive electrode sheet, the size of the coating portion of the positive electrode sheet along the length direction Z of the battery cell 7 is a first size, and the size of the coating portion of the positive electrode sheet along the width direction Y of the battery cell 7 is a first size. Figure 14 W2 represents the dimension of the coating portion of the positive electrode sheet along the length direction Z, and Y1 represents the dimension of the coating portion of the positive electrode sheet along the width direction Y.

[0312] If the ratio of the length of the coating portion of the positive electrode plate to the width of the coating portion is too small, for example, less than 4, the load of active material is relatively small, which is not conducive to improving the energy density of the battery cell; if the ratio of the length of the coating portion of the electrode plate to the width of the coating portion is too large, for example, greater than 7, the length of the coating portion of the positive electrode plate is too long, the transmission path of electrons in the length direction of the positive electrode plate is too long, the resistance increases, and is not conducive to improving the fast charging performance of the battery cell.

[0313] The ratio of the length of the coated portion of the positive electrode sheet to the width of the coated portion is 4 to 7, such as 4, 4.5, 5, 5.5, 6, 6.5, 7 or a range consisting of any two of the above values, which can improve both the energy density and fast charging performance of the battery cell.

[0314] In some embodiments, the length of the coated portion of the positive electrode sheet is 300 mm to 650 mm, for example, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm, or a range consisting of any two of the foregoing values. Alternatively, the length of the coated portion of the positive electrode sheet is 400 mm to 500 mm. When the length of the coated portion of the positive electrode sheet falls within the above range, both the energy density and fast charging performance of the battery cell can be improved.

[0315] Next, a related solution in which the first direction is parallel to the width direction Y of the first pole piece 11 is described.

[0316] like Figure 15 As shown, in some embodiments, the first pole piece 11 includes one or more first pole tabs 111 , and the one or more first pole tabs 111 are disposed on at least one side of the coating portion along the width direction Y.

[0317] For example, one or more first pole ears 111 are arranged on one side of the first coating portion 112 along the width direction Y. In this case, it can be understood that all first pole ears 111 are arranged on the same side of the first coating portion 112 along the width direction Y. This arrangement is beneficial to increase the occupied space of the electrode assembly 10, thereby improving the energy density of the battery cell 7.

[0318] When all the first electrode tabs 111 are disposed on the same side of the first coating portion 112 along the width direction Y, the dimension of the first coating portion 112 along the width direction Y is 80 mm to 150 mm.

[0319] Figure 15 Y1 represents the dimension of the first coating portion 112 along the width direction Y, which can also be understood as the width of the first coating portion 112 .

[0320] like Figure 16As shown, for example, in the case where the first electrode sheet 11 includes a plurality of first electrode tabs 111 , the plurality of first electrode tabs 111 are disposed on both sides of the first coating portion 112 along the width direction Y.

[0321] When the plurality of first electrode tabs 111 are disposed on both sides of the first coating portion 112 along the width direction Y, the dimension of the first coating portion 112 along the width direction Y is 80 mm to 150 mm.

[0322] Figure 16 Y1 represents the dimension of the first coating portion 112 along the width direction Y, which can also be understood as the width of the first coating portion 112 .

[0323] Regardless of whether all first electrode tabs 111 are disposed on the same side of the first coating portion 112 along the width direction Y, or all first electrode tabs 111 are disposed on both sides of the first coating portion 112 along the width direction Y, the number of first electrode tabs 111 located on the same side of the first coating portion 112 may be at least two, for example, two, three, four, five, six, etc.; four may be selected. This arrangement facilitates uniform distribution of electrons in the first electrode sheet 11 and improves fast charging performance.

[0324] Optionally, the spacing between two adjacent pole ears along the length direction Z is greater than 0 and less than or equal to 300 mm, for example, 100 mm, 120 mm, 140 mm, 150 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 250 mm, 260 mm, 280 mm, 300 mm or a range consisting of any two of the above values. Figure 16 Z1 represents the distance between two adjacent pole ears along the length direction Z.

[0325] Next, a related solution in which the first direction is parallel to the length direction of the first pole piece 11 is described.

[0326] like Figure 17 As shown, in some embodiments, the first electrode piece 11 includes one or more first electrode tabs 111 ; the one or more first electrode tabs 111 are disposed on at least one side of the first coating portion 112 along the length direction Z.

[0327] For example, one or more first electrode tabs 111 are disposed on one side of the first coating portion 112 along the length direction Z. In this case, it can be understood that all first electrode tabs 111 are disposed on the same side of the first coating portion 112 along the length direction Z.

[0328] When all the first electrode tabs 111 are disposed on the same side of the first coating portion 112 along the length direction Z, the dimension of the first coating portion 112 along the length direction Z is 80 mm to 150 mm.

[0329] Figure 17In FIG. 1 , Z2 represents the dimension of the first coating portion 112 along the length direction Z, and can also be understood as the length of the first coating portion 112 .

[0330] like Figure 18 As shown, for example, in the case where the first electrode sheet 11 includes a plurality of first electrode tabs 111 , the plurality of first electrode tabs 111 are respectively disposed on both sides of the first coating portion 112 along the length direction Z.

[0331] Optionally, a plurality of first electrode tabs 111 are respectively arranged on both sides of the first coating portion 112 along the length direction Z. This arrangement can shorten the transmission path of electrons in the first electrode sheet 11, which is conducive to improving the fast charging performance.

[0332] When the plurality of first electrode tabs 111 are respectively disposed on both sides of the first coating portion 112 along the longitudinal direction Z, the dimension of the first coating portion 112 along the longitudinal direction Z is 300 mm to 650 mm.

[0333] Figure 18 In FIG. 1 , Z3 represents the dimension of the first coating portion 112 along the length direction Z, and can also be understood as the length of the first coating portion 112 .

[0334] Regardless of whether all the first electrode tabs 111 are disposed on the same side of the first coating portion 112 along the width direction Y, or all the first electrode tabs 111 are disposed on both sides of the first coating portion 112 along the width direction Y, the number of first electrode tabs 111 located on the same side of the first coating portion 112 may be at least two, for example, two, three, four, five, six, etc. This arrangement facilitates uniform distribution of electrons in the first electrode sheet 11 and improves fast charging performance.

[0335] Optionally, the spacing between two adjacent tabs along the width direction Y is greater than zero and less than or equal to 300 mm, such as 100 mm, 120 mm, 140 mm, 150 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 250 mm, 260 mm, 280 mm, 300 mm, or a range consisting of any two of the foregoing values. This arrangement can further shorten the electron transmission path, effectively reducing the internal resistance of the battery cell. Furthermore, each tab carries less current, resulting in more uniform current distribution. Figure 10 Y2 represents the distance between two adjacent pole ears along the width direction Y. Figure 17 In FIG, Y2 represents the distance between two adjacent pole ears along the width direction Y.

[0336] In the embodiment of the present application, the number and arrangement of the second tabs 121 are similar to those of the first tabs 111 and are not described in detail here. The structure of the second pole piece 12 is similar to that of the first pole piece 11 and is not described in detail here.

[0337] [Electrolyte]

[0338] During the charge and discharge process of a battery cell, active ions such as lithium ions are embedded and released back and forth between the positive electrode and the negative electrode, and the electrolyte plays the role of conducting active ions between the positive electrode and the negative electrode.

[0339] The electrolyte salt includes a lithium salt, which includes lithium bis(fluorosulfonyl)imide and may further include lithium hexafluorophosphate (LiPF6). The above lithium salt is beneficial for increasing the total amount of lithium ion migration in the electrolyte, improving the lithium ion capacity, and enhancing the dynamic performance of the battery cell.

[0340] Optionally, based on the mass of the electrolyte, the ratio of the mass content of lithium hexafluorophosphate to the mass content of lithium bis(fluorosulfonyl)imide is 0.5 to 4, and optionally 1.2 to 2.0. The lithium salt helps increase the total amount of lithium ion migration in the electrolyte, improves the lithium ion capacity, and enhances the dynamic performance of the battery cell.

[0341] Illustratively, the mass content of lithium hexafluorophosphate and the mass content of lithium bis(fluorosulfonyl)imide are 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, 1.9, 2.1, 2.3, 2.5, 2.7, 2.9, 3.1, 3.3, 3.5, 3.7, 3.9, 4.0, or a range consisting of any two of the above values.

[0342] In the embodiments of this application, the mass content of lithium bis(fluorosulfonyl)imide is 1% to 15% based on the mass of the electrolyte, and optionally 3% to 12%. When the lithium salt meets the above conditions, it is beneficial to increase the total amount of lithium ion migration in the electrolyte, improve the lithium ion capacity, and enhance the dynamic performance of the battery cell.

[0343] Illustratively, based on the mass of the electrolyte, the mass content of lithium bis(fluorosulfonyl)imide is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or a range consisting of any two of the above values.

[0344] In some embodiments, the lithium salt content is 13% to 20% by weight, based on the mass of the electrolyte, such as 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or a range consisting of any two of these values. When the lithium salt content is within the above range, the lithium salt helps improve the conductivity of the electrolyte and enhance the dynamic performance of the battery cell.

[0345] In some embodiments, the electrolyte has a conductivity of 10 mS / cm to 13 mS / cm at room temperature. For example, the electrolyte has a conductivity of 10 mS / cm, 10.5 mS / cm, 11 mS / cm, 11.5 mS / cm, 12 mS / cm, 12.5 mS / cm, 13 mS / cm, or a range consisting of any two of these values ​​at room temperature.

[0346] When the conductivity of the electrolyte at room temperature, such as 25° C., is within the above range, the migration rate of lithium ions in the electrolyte is high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0347] In the embodiment of the present application, the conductivity of the electrolyte at room temperature, for example, 25° C., is ionic conductivity, which can be tested using equipment and methods known in the art, for example, by referring to the industry standard HG-T 4067-2015.

[0348] In some embodiments, the organic solvent includes a carbonate-based solvent.

[0349] Optionally, the mass content of the carbonate solvent in the electrolyte is 10% to 80%. Exemplarily, the mass content of the carbonate solvent in the organic solvent is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, or a range consisting of any two of the above values. The above mass content of carbonate solvent can further improve the conductivity of the electrolyte at room temperature, which is beneficial to the migration of lithium ions; and the mass content of carbonate solvent is not too high, which can reduce high-temperature gas production and improve high-temperature cycle performance.

[0350] Optionally, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Further optionally, the carbonate solvent includes one or more of dimethyl carbonate and ethylene carbonate. Even further optionally, the carbonate solvent includes dimethyl carbonate. The combination of the above carbonate solvent and the chain carboxylate solvent improves the conductivity of the electrolyte at room temperature, which is beneficial to the migration of lithium ions.

[0351] In some embodiments, the organic solvent includes a linear carboxylate solvent.

[0352] Optionally, the mass content of the chain carboxylate solvent in the electrolyte is 5% to 30%. Exemplarily, the mass content of the chain carboxylate solvent is 5%, 10%, 15%, 20%, 25%, 30%, or a range consisting of any two of the above values.

[0353] When the mass content of the chain carboxylate solvent is within the above range, the viscosity of the electrolyte system is relatively small, which is conducive to the migration of lithium ions; and the mass content of the chain carboxylate solvent is not too high, which can reduce high-temperature gas production and improve high-temperature cycle performance.

[0354] In some embodiments, the linear carboxylate solvent includes a compound represented by Formula I,

[0355] Formula I,

[0356] In Formula I,

[0357] R1 includes a hydrogen atom, a C1 to C5 alkyl group or a C1 to C5 halogenated alkyl group,

[0358] R2 includes C1 to C5 alkyl or C1 to C5 halogenated alkyl.

[0359] The above-mentioned chain carboxylic acid ester solvents have high electrical conductivity, which is beneficial to improving the fast charging capability of battery cells.

[0360] Alternatively, R1 includes a hydrogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group. Further alternatively, R1 includes a hydrogen atom, a halogen atom, a C1 to C2 alkyl group, or a C1 to C2 haloalkyl group.

[0361] Alternatively, R2 comprises a C1 to C3 alkyl group or a C1 to C3 haloalkyl group. Further alternatively, R2 comprises a C1 to C2 alkyl group or a C1 to C2 haloalkyl group.

[0362] In each of the above embodiments, the haloalkyl group includes one or more of a fluoroalkyl group, a chloroalkyl group, a bromoalkyl group and an iodoalkyl group. Optionally, the haloalkyl group includes a fluoroalkyl group.

[0363] Illustratively, the chain carboxylate solvent includes one or more compounds represented by formula I-1 to formula I-8.

[0364]

[0365] In some embodiments, the electrolyte further contains additives, which may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature power performance, etc.

[0366] In some embodiments, the additives include one or more of carbonate additives and sulfur-containing additives, and optionally at least two of these additives. These additives can improve the interfacial film properties on the positive electrode side and / or the negative electrode side, thereby enhancing the fast charging performance of the battery cell and improving the cycling performance.

[0367] In some embodiments, the weight content of the additive in the electrolyte is 0.5% to 6%. For example, the weight content of the additive in the electrolyte is 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6%, or a range consisting of any two of the above values.

[0368] The above-mentioned organic solvents, such as chain carboxylic acid ester solvents, may decompose and produce acid at high temperatures, corroding the interface film on the surface of the negative electrode. The additives can form a dense and uniform film layer on the negative electrode side, which can effectively repair the interface film and provide excellent protection for the negative electrode active material, which is beneficial to improving the fast charging performance of the battery cell and improving the cycle performance.

[0369] Illustratively, the carbonate additive includes one or more of vinylene carbonate VC and fluoroethylene carbonate FEC. Optionally, the carbonate additive includes vinylene carbonate VC and fluoroethylene carbonate FEC.

[0370] Illustratively, the sulfur-containing additive includes one or more of vinyl sulfate DTD, vinyl disulfate 2-DTD, butylene sulfite BS, 1,3-propane sultone PS, vinyl sulfite ES, and methylene disulfonate MMDS, and 1,3-propane sultone PS may be selected.

[0371] Illustratively, the additive includes one or more of vinylene carbonate, fluoroethylene carbonate, and 1,3-propane sultone.

[0372] Optionally, the mass content of vinylene carbonate VC in the electrolyte is 0.5% to 3.0%, 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%, 2.0%, 2.5%, 3.0% or a range consisting of any two of the above values.

[0373] Optionally, the mass content of fluoroethylene carbonate FEC in the electrolyte is 0.2% to 2.5%, for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.5%, 2.0%, 2.5% or a range consisting of any two of the above values.

[0374] Optionally, the mass content of 1,3-propane sultone PS in the electrolyte is 0.5% to 2.5%, 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%, 2.0%, 2.5%, or a range consisting of any two of the above values.

[0375] In the embodiments of the present application, the types and contents of the inorganic components / lithium salts in the electrolyte are well known in the art and can be detected using equipment and methods well known in the art. For example, the inorganic components / lithium salts in the electrolyte can be qualitatively or quantitatively analyzed by ion chromatography analysis method with reference to standard JY / T020-1996 "General Rules for Ion Chromatography Analysis Methods". In the embodiments of the present application, a freshly prepared electrolyte can be taken as a sample, the free electrolyte of a fresh battery can be taken as a sample, or a battery that has been fully discharged (discharged to the lower cut-off voltage so that the battery's state of charge is approximately 0% SOC) can be reversely disassembled, and the free electrolyte obtained from the battery can be used as a sample for detection using ion chromatography analysis method.

[0376] In the embodiment of the present application, the types and contents of the organic components in the electrolyte are well known in the art and can be detected using equipment and methods well known in the art. For example, reference can be made to GB / T9722-2006 "General Rules for Gas Chromatography of Chemical Reagents" to perform qualitative and quantitative analysis of the organic components in the electrolyte by gas chromatography.

[0377] In the embodiment of the present application, after quantitative and qualitative detection of each component in the electrolyte, the components are classified, and the chain carboxylate solvent and carbonate solvent (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate) are used as components of the organic solvent. The mass content of each component is calculated based on the mass of the electrolyte as 100%.

[0378] Carbonate additives (such as vinylene carbonate and fluoroethylene carbonate) and sulfur-containing additives are used as additives for the electrolyte. The mass content of each component is calculated based on the mass of the electrolyte being 100%.

[0379] In the embodiment of the present application, after quantitative and qualitative detection of each component in the electrolyte, the components are classified, and the chain carboxylate solvent and carbonate solvent (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate) are used as components of the organic solvent. The mass content of each component is calculated based on the mass of the electrolyte as 100%.

[0380] Carbonate additives (such as vinylene carbonate and fluoroethylene carbonate) and sulfur-containing additives are used as additives for the electrolyte. The mass content of each component is calculated based on the mass of the electrolyte being 100%.

[0381] Positive electrode

[0382] In order to explain the present application more clearly, the coating portion of the positive electrode sheet corresponds to the positive electrode coating portion, the ear portion corresponds to the positive electrode ear, the active material layer corresponds to the positive electrode film layer containing the positive electrode active material, and the positive electrode coating portion includes a positive electrode current collecting portion and a positive electrode film layer arranged on at least one side of the positive electrode current collecting portion.

[0383] The positive electrode sheet includes a positive current collector and a positive electrode film layer comprising a positive electrode active material and disposed on at least one surface of the positive current collector. For example, the positive current collector may have two opposing surfaces in the thickness direction of the positive current collector, and the positive electrode film layer may be disposed on one or both of the two opposing surfaces of the positive current collector.

[0384] The upper limit voltage for charging and the cut-off voltage for discharging of the battery cell vary depending on the different positive electrode active materials. For example, when the phosphate material includes lithium iron phosphate, the upper limit voltage for charging may be 3.65V and the cut-off voltage for discharging may be 2.0V, or the upper limit voltage for charging may be 3.8V and the cut-off voltage for discharging may be 2.0V. For another example, when the phosphate material includes lithium manganese iron phosphate, the upper limit voltage for charging may be 4.3V and the cut-off voltage for discharging may be 2.0V. Next, taking the upper limit voltage for charging of 3.65V and the cut-off voltage for discharging of 2.0V as an example, the state of the battery cell is described: In the embodiment of the present application, the 100% state of charge SOC and the 0% state of charge SOC of the battery cell are defined as follows:

[0385] The battery cell is charged at a constant current charge rate of 0.33C to the upper limit of the charge voltage, and then charged at a constant voltage to 0.05C, corresponding to the state of 100% SOC of the battery cell. The battery cell is discharged at a constant current discharge rate of 0.33C to the cut-off voltage, corresponding to the state of 0% SOC of the battery cell.

[0386] In some embodiments, the compaction density of the positive electrode film layer of the battery cell at 0% state of charge SOC is 2.30 g / cm 3 to 2.70g / cm 3 ; Optional 2.40g / cm 3 Up to 2.55g / cm 3 For example, when the battery cell is at 0% state of charge (SOC), the compaction density of the positive electrode film is 2.30 g / cm 3 , 2.32g / cm 3 , 2.35g / cm 3 , 2.38g / cm3 , 2.40g / cm 3 , 2.42g / cm 3 , 2.45g / cm 3 , 2.48g / cm 3 , 2.50g / cm 3 , 2.52g / cm 3 , 2.55g / cm 3 , 2.56g / cm 3 , 2.57g / cm 3 , 2.58g / cm 3 , 2.60g / cm 3 , 2.62g / cm 3 , 2.65g / cm 3 , 2.68g / cm 3 , 2.70g / cm 3 Or a range consisting of any two of the above values.

[0387] When the compaction density of the positive electrode film layer is within the above range, it is beneficial to improve the single cell energy of the battery cell and increase the energy density; and because the positive electrode active material of the positive electrode film layer is stacked relatively densely, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing the heat generation under fast charging and improving the fast charging capability of the battery cell.

[0388] In some embodiments, the single-sided coating weight of the positive electrode film layer is 250 mg / 1540.25 mm 2 Up to 330mg / 1540.25mm 2 , optional 275mg / 1540.25mm 2 Up to 300mg / 1540.25mm 2 For example, the coating weight of the positive electrode film on one side is 250 mg / 1540.25 mm 2 、260mg / 1540.25mm 2 、270mg / 1540.25mm 2 、280mg / 1540.25mm 2 、290mg / 1540.25mm 2 、300mg / 1540.25mm 2 、310mg / 1540.25mm 2 、320mg / 1540.25mm 2 、330mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0389] When the single-sided coating weight of the positive electrode film layer is within the above range, it is beneficial to improve the single-cell energy of the battery cell and increase the energy density; the heat generation per unit area of ​​the positive electrode sheet will not be too large, which can improve the fast charging capability of the battery cell.

[0390] In the embodiments of the present application, the compacted density of the positive electrode film layer of a battery cell at 0% state of charge (SOC) has a meaning well known in the art. Specifically, the positive electrode sheet of a battery cell at 0% state of charge (SOC) is disassembled and the compacted density of the positive electrode film layer is measured. For example, a single-sided coated positive electrode sheet (if a double-sided coated sheet, the positive electrode film layer on one side can be wiped off first) is punched into small discs with an area of ​​S1. The discs are weighed and recorded as M1, and their thickness H1 is measured. The positive electrode film layer of the weighed positive electrode sheet is then wiped off, and the weight of the positive current collector is weighed and recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the positive electrode film layer = (weight of the positive electrode sheet M1 - weight of the positive current collector M0) / S1. The thickness of the positive electrode film layer = thickness of the positive electrode sheet H1 - thickness of the positive current collector H0. The compacted density of the positive electrode film layer = single-sided coating weight of the positive electrode film layer / thickness of the positive electrode film layer.

[0391] In some embodiments, the positive electrode active material includes a lithium-containing phosphate with an olivine structure. In other embodiments, the positive electrode active material may also include a lithium-containing transition metal oxide, etc. Examples of lithium-containing transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and modified compounds thereof.

[0392] In the embodiment of the present application, the lithium-containing phosphate with an olivine structure can be phosphate particles, or a material obtained by coating and modifying the phosphate particles. For example, the lithium-containing phosphate with an olivine structure includes phosphate particles and a coating layer. The coating layer is coated on the surface of the phosphate particles. For example, the coating layer includes elements such as carbon, which improves the conductivity of the phosphate particles, reduces the powder resistivity of the material, and is beneficial to the migration rate of lithium ions, thereby improving the fast charging capability of the battery and reducing the heat generation of the battery cell.

[0393] In some embodiments, the phosphate particles include a general formula of Li x1 A y1 Me a M b P 1-c X c Y zCompounds wherein 0.5≤x1≤1.3, 0≤y1≤1.3, and 0.9≤x1+y1≤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, and Mg, Me comprises one or more of Mn, Fe, Co, and 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, and Ce, X comprises one or more of Cl, C, and N, and Y comprises one or more of O and F. The phosphate particles have excellent cycling stability, which is beneficial for improving the cycling performance of battery cells.

[0394] Exemplarily, the phosphate particles include one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. The battery cells are accompanied by the deintercalation and consumption of active ions such as Li during the charge and discharge process, and the molar content of Li in the battery cells is different when discharged to different states. In the enumeration of positive electrode active materials LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc., the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li may change after charge and discharge cycles. In the enumeration of positive electrode active materials LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc. in the embodiment of the present application, the molar content of oxygen O is only a theoretical state value. Lattice oxygen release will cause the molar content of oxygen O to change. In practice, the molar content of oxygen O will fluctuate. The above situations are all within the scope of protection of this application.

[0395] In the embodiments of this application, the element content in the positive electrode active material has a meaning well known in the art and can be measured using equipment and methods well known in the art. For example, in accordance with EPA 6010D-2014, it can be measured by inductively coupled plasma atomic emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400). After discharging the battery cell to 0% state of charge (SOC), the positive electrode sheet is disassembled, cleaned with dimethyl carbonate (DMC), dried, and calcined at high temperature to remove impurities. Then, 0.4g of the positive electrode active material is weighed and 10ml (50% concentration) of aqua regia is added. The sample is then placed on a plate at 180°C for 30 minutes. After digestion on the plate, the volume is adjusted to 100ml, and quantitative analysis is performed using a standard curve method.

[0396] In some embodiments, the positive electrode film layer further includes a positive electrode additive, which may include lithium elements and can release lithium ions during the charging process of the battery cell to compensate for lithium loss, thereby improving the capacity characteristics and cycle performance of the battery cell.

[0397] In some embodiments, the positive electrode additive includes at least one of lithium ferrite particles or lithium nickelate particles.

[0398] In some embodiments, the average longest diameter of the positive electrode additive is 2 μm to 5 μm, such as 2 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or any range consisting of two thereof.

[0399] In the embodiment of the present application, the positive electrode sheet is cut along the thickness direction of the sheet to expose the longitudinal section of the positive electrode film layer. The longitudinal section of the positive electrode film layer is subjected to scanning electron microscopy (SEM) testing to determine the longest and shortest diameters of the positive electrode additive particles and the longest diameter of the lithium-containing phosphate. For example, the "longest diameter" of a particle refers to the longest straight line passing through the center point of the particle and extending to the periphery of the particle.

[0400] In a cross section of the positive electrode film along its own thickness direction, the longest diameters of a plurality of, for example, 10, lithium-containing iron oxides are counted, and the average value thereof is calculated as the average longest diameter.

[0401] In some embodiments, the mass content of the positive electrode additive is 0.2% to 2% based on the total mass of the positive electrode film layer, for example, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, or any range thereof. When a positive electrode additive within this mass range is used, lithium replenishment can be effectively achieved.

[0402] In some embodiments, the positive electrode film layer may further optionally include a positive electrode conductive agent. The present application does not particularly limit the type of positive electrode conductive agent. For example, the positive electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass content of the positive electrode conductive agent is ≤5% based on the mass of the positive electrode film layer.

[0403] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. The embodiments of the present application do not particularly limit the type of positive electrode binder. As an example, the positive electrode binder may include at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorine-containing acrylic resin. In some embodiments, based on the mass of the positive electrode film layer, the mass content of the positive electrode binder is ≤5%.

[0404] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0405] In some embodiments, the ratio of the thickness of the positive electrode film layer on a single side to the thickness of the positive electrode current collector is 3 to 10, for example, 3, 4, 5, 6, 7, 8, 9, 10, or a range consisting of any two of the foregoing values. Alternatively, the ratio of the thickness of the positive electrode film layer on a single side to the thickness of the positive electrode current collector is 4 to 8.

[0406] When the ratio of the thickness of the single-sided positive electrode film layer to the thickness of the positive electrode current collecting portion is within the above range, the fast charging capability and energy density of the battery cell can be improved.

[0407] In some embodiments, the thickness of the positive electrode current collector is 12 μm to 16 μm, optionally 13 μm to 15 μm. For example, the thickness of the positive electrode current collector is 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, or a range consisting of any two of the above values.

[0408] When the thickness of the positive electrode current collecting portion is within the above range, the positive electrode current collecting portion has a relatively excellent current flow capacity and can enable the battery cell to have a relatively high energy density.

[0409] In the embodiment of the present application, the thickness of the positive electrode film layer and the positive electrode current collecting portion has a meaning well known in the art and can be detected by using equipment and methods well known in the art. For example, a caliper is used to measure the thickness of the positive electrode sheet, the film layer on the surface of the positive electrode current collecting portion is removed, and the thickness of the positive electrode current collecting portion is measured with a caliper. When the positive electrode film layer is coated on one side, the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive electrode current collecting portion. When the positive electrode film layer is coated on both sides, the thickness of the positive electrode film layer is (the thickness of the positive electrode sheet minus the thickness of the positive electrode current collecting portion) / 2.

[0410] The positive electrode film is typically formed by coating a positive electrode slurry onto the positive electrode current collector, drying it, and cold pressing it. The positive electrode slurry is typically formed by dispersing the positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP).

[0411] The positive electrode sheet does not exclude other additional functional layers in addition to the positive electrode film layer. For example, in some embodiments, the positive electrode sheet of the embodiments of the present application further includes a positive electrode conductive layer sandwiched between the positive electrode current collector and the positive electrode film layer and disposed on the surface of the positive electrode current collector. In other embodiments, the positive electrode sheet of the embodiments of the present application further includes a protective layer covering the surface of the positive electrode film layer.

[0412] Negative electrode

[0413] In order to explain the present application more clearly, the coating portion of the negative electrode sheet corresponds to the negative electrode coating portion, the ear portion corresponds to the negative electrode ear, the active material layer corresponds to the negative electrode film layer containing the negative electrode active material, the negative electrode coating portion includes a negative electrode current collecting portion and a negative electrode film layer arranged on at least one side of the negative electrode current collecting portion, and the negative electrode coating portion includes a negative electrode current collecting portion and a negative electrode film layer arranged on at least one side of the negative electrode current collecting portion.

[0414] The negative electrode sheet includes a negative current collector and a negative electrode film layer comprising a negative electrode active material disposed on at least one surface of the negative current collector. For example, the negative current collector may have two opposing surfaces in the thickness direction of the negative current collector, and the negative electrode film layer may be disposed on either or both of the two opposing surfaces of the negative current collector.

[0415] In some embodiments, the compaction density of the negative electrode film layer of the battery cell at 0% state of charge (SOC) is 1.30 g / cm 3 Up to 1.65g / cm 3 ; Optional 1.35g / cm 3 Up to 1.50g / cm 3 For example, the compaction density of the negative electrode film layer of the battery cell at 0% state of charge is 1.3 g / cm 3 , 1.32g / cm 3 , 1.35g / cm 3 , 1.40g / cm 3 , 1.45g / cm 3 , 1.50g / cm 3 , 1.55g / cm 3 , 1.60g / cm 3 , 1.65g / cm 3 Or a range consisting of any two of the above values.

[0416] When the compaction density of the negative electrode film layer is within the above range, it is beneficial to improve the single cell energy of the battery cell and improve the energy density; and because the negative electrode active material of the negative electrode film layer is stacked relatively densely, the contact resistance between particles is small, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0417] In the embodiment of the present application, the compaction density of the negative electrode film layer of the battery cell at 0% state of charge SOC has a meaning well known in the art and can be detected using equipment and methods well known in the art, and its detection method is the same as the compaction density test method of the positive electrode film layer mentioned above.

[0418] In some embodiments, the single-sided coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 Up to 180mg / 1540.25mm 2 , optional 125mg / 1540.25mm 2 Up to 150mg / 1540.25mm 2 For example, the coating weight of the negative electrode film on one side is 120 mg / 1540.25 mm 2 、122mg / 1540.25mm 2 、125mg / 1540.25mm 2 、128mg / 1540.25mm 2 、130mg / 1540.25mm 2 、132mg / 1540.25mm 2 、135mg / 1540.25mm 2 、137mg / 1540.25mm 2 、140mg / 1540.25mm 2 、145mg / 1540.25mm 2 、150mg / 1540.25mm 2 、155mg / 1540.25mm 2 、160mg / 1540.25mm 2 、165mg / 1540.25mm 2 、170mg / 1540.25mm 2 、175mg / 1540.25mm 2 、180mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0419] When the single-sided coating weight of the negative electrode film layer is within the above range, it is beneficial to increase the single-cell energy of the battery cell and improve the energy density; and the heat generation per unit area of ​​the negative electrode sheet will not be too large, which can improve the fast charging capability of the battery cell.

[0420] In the embodiment of the present application, the single-sided coating weight of the negative electrode film layer has a meaning well known in the art and can be detected using equipment and methods well known in the art, such as the single-sided coating weight test method of the film layer described above.

[0421] In some embodiments, the negative electrode active material includes a carbon-based material, which has high cycling stability and can improve the cycling performance of the battery cell. The positive electrode active material of this application is primarily an olivine-structured lithium-containing phosphate system, and the negative electrode active material is primarily a carbon-based material system. The combination of the two results in excellent cycling performance for the battery cell.

[0422] Optionally, the carbon-based material includes artificial graphite, and the degree of graphitization of the artificial graphite is 90% to 95%, optionally 92% to 95%. Exemplarily, the degree of graphitization of the artificial graphite is 90%, 90.5%, 91%, 91.5%, 92.0%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, or a range consisting of any two of the above values.

[0423] When the degree of graphitization of the artificial graphite is within the above range, the artificial graphite has excellent electrical conductivity, can reduce the heat generation of the negative electrode sheet, reduce the heat generation of the battery cell, and can improve the fast charging performance of the battery cell.

[0424] In some embodiments, the carbon-based material may further include natural graphite. Specifically, the carbon-based material may include artificial graphite, or the carbon-based material may include artificial graphite and natural graphite.

[0425] In some embodiments, the negative electrode active material may include at least one of a tin-based material and lithium titanate, in addition to the aforementioned carbon-based material and optionally a silicon-based material. The tin-based material may include at least one of elemental tin, tin oxide, and a tin alloy. Alternatively, the silicon-based material may include at least one of elemental silicon, silicon oxide, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy.

[0426] The qualitative and quantitative properties of each substance or element in this application can be detected using appropriate equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and international detection standards, domestic and international enterprise standards, etc., and those skilled in the art can also adapt certain detection steps / instrument parameters, etc. from the perspective of detection accuracy to obtain more accurate detection results. A single detection method can be used for qualitative or quantitative determination, or several detection methods can be used in combination for qualitative or quantitative determination.

[0427] For example, the present application may combine JIS / K0131-1996 General Rules for X-ray Diffraction Analysis Methods to perform X-ray powder diffraction testing and qualitative analysis on the negative electrode sheet or negative electrode active material.

[0428] Artificial graphite and natural graphite can be distinguished by the SEM cross-section taken by a scanning electron microscope (SEM). The SEM cross-section of natural graphite shows gaps between the flake structures, while the SEM cross-section of artificial graphite is dense and has no obvious gaps. They can also be distinguished by the XRD spectrum obtained by the X-ray diffraction method. The XRD spectrum of natural graphite shows obvious 2H phase and 3R phase, while the XRD spectrum of artificial graphite only shows 2H phase.

[0429] In the embodiment of the present application, the negative electrode film layer includes at least one film layer, which can be a single film layer or at least two film layers. Optionally, the negative electrode film layer includes at least two film layers.

[0430] In the case where the negative electrode film layer adopts a single-layer film layer, the negative electrode active material in the negative electrode film layer includes a carbon-based material. In the case of a single-layer film layer, the volume average particle size Dv50 of the carbon-based material is 8μm to 13μm, and can be optionally 9.5μm to 11.5μm. Exemplarily, the volume average particle size Dv50 of the carbon-based material is 8μm, 8.5μm, 8.8μm, 9μm, 9.2μm, 9.5μm, 9.8μm, 10μm, 10.2μm, 10.5μm, 10.8μm, 11μm, 11.2μm, 11.5μm, 11.8μm, 12μm, 12.2μm, 12.5μm, 12.8μm, 13μm or a range consisting of any two of the above values.

[0431] In the case where the negative electrode film layer comprises at least two film layers, the negative electrode active material in the negative electrode film layer comprises a carbon-based material. The negative electrode film layer may comprise two film layers, three film layers, four film layers, or even more film layers.

[0432] In some embodiments, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, the first negative electrode film layer being disposed on a surface of a negative electrode current collector, the carbon-based material of the first negative electrode film layer including artificial graphite, the second negative electrode film layer being connected to a side of the first negative electrode film layer facing away from the negative electrode current collector, the carbon-based material of the second negative electrode film layer including artificial graphite, and the artificial graphite of the first negative electrode film layer and the artificial graphite of the second negative electrode film layer may be the same or different. When the artificial graphite of the first negative electrode film layer and the artificial graphite of the second negative electrode film layer are different, they may have different particle sizes or different degrees of graphitization.

[0433] The interface between the first negative electrode film layer and the second negative electrode film layer may be regular or irregular, and may optionally be irregular.

[0434] The negative electrode film comprises at least two layers, and layered coating can improve the rapid charging performance of the battery cell. In particular, when the first and second negative electrode film layers are different, the pores of the negative electrode film layers can be differentiated, reducing the tortuosity of lithium-ion transport and improving the rapid charging performance of the battery cell.

[0435] In some embodiments, the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is greater than or equal to the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer. Further optionally, the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is greater than the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer, which is beneficial to improving the dynamic performance of the negative electrode film layer.

[0436] There is a difference in the particle size of the first negative electrode film layer and the second negative electrode film layer, which can improve the fast charging performance of the battery cell. Specifically, during the fast charging process, the overpotential of the second negative electrode film layer is usually higher, and the bottleneck of fast charging mainly lies in the second negative electrode film layer. In the embodiment of the present application, the particle size of the second negative electrode film layer is relatively small, which can shorten the solid-phase transmission path of lithium ions, improve the fast charging performance, and improve the problem of lithium plating on the surface of the negative electrode sheet.

[0437] Optionally, the carbon-based material of the first negative electrode film layer is granular, and its volume average particle size Dv50 is 9.0 μm to 18.5 μm, and optionally 9.0 μm to 14.6 μm. Exemplarily, the volume average particle size of the carbon-based material of the second negative electrode film layer is 9.0 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 14.6 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, or a range consisting of any two of the above values. When the first negative electrode film layer includes a carbon-based material, the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is 9.0 μm to 18.5 μm, and optionally 9.0 μm to 14.6 μm.

[0438] When the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is within the above range, on the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance; on the other hand, the material is not easy to agglomerate during the preparation process, which can improve the stability of the material.

[0439] Optionally, the carbon-based material of the second negative electrode film layer is granular, and its volume average particle size Dv50 is 7.8 μm to 14.3 μm, and optionally 7.8 μm to 11.3 μm. Exemplarily, the volume average particle size Dv50 of the carbon-based material is 7.8μm, 8.0μm, 8.2μm, 8.5μm, 8.8μm, 9μm, 9.2μm, 9.5μm, 9.8μm, 10μm, 10.2μm, 10.5μm, 10.8μm, 11μm, 11.3μm, 11.2μm, 11.5μm, 11.8μm, 12μm, 12.2μm, 12.5μm, 12.8μm, 13μm, 13.2μm, 13.5μm, 13.8μm, 14μm, 14.1μm, 14.3μm or a range consisting of any two of the above values. When the second negative electrode film layer includes a carbon-based material, the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is 7.8 μm to 14.3 μm, and optionally 7.8 μm to 11.3 μm.

[0440] When the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is within the above range, the solid-phase transmission path of lithium ions can be shortened and the fast charging performance can be improved.

[0441] When the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is within the above range, on the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance; on the other hand, the material is not easy to agglomerate during the preparation process, which can improve the stability of the material; on the other hand, the combination of the negative electrode active material in the second negative electrode film layer within the above volume average particle size range and the negative electrode active material in the first negative electrode film layer is beneficial to constructing a gradient pore difference between the second negative electrode film layer and the first negative electrode film layer, reducing the tortuosity of lithium ion transmission, and improving the fast charging performance of the battery cell.

[0442] In the embodiment of the present application, the volume average particle size Dv50 of the negative electrode active material has a meaning well known in the art and can be detected using equipment and methods well known in the art. For example, the negative electrode active material is used as a sample and the Dv50 and Dv10 of the particles are tested using a Mastersizer 2000E laser particle size analyzer in accordance with the test standard GB / T 19077-2016.

[0443] Optionally, the carbon-based material of the first negative electrode film layer further includes natural graphite.

[0444] Illustratively, the carbon-based material of the first negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer includes artificial graphite.

[0445] In other embodiments, the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is greater than the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer. Further optionally, the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is greater than the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer, which is beneficial to improving the compaction density of the negative electrode film layer.

[0446] The difference in particle size between the first negative electrode film layer and the second negative electrode film layer can improve the fast charging performance of the battery cell.

[0447] Optionally, the carbon-based material of the second negative electrode film layer is granular, and its volume average particle size Dv50 is 9.0 μm to 18.5 μm, and optionally 9.0 μm to 14.6 μm. When the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer is within the above range, on the one hand, the solid-phase transmission path of lithium ions can be shortened, thereby improving the fast charging performance. On the other hand, the material is less likely to agglomerate during the preparation process, thereby improving the stability of the material.

[0448] Optionally, the carbon-based material of the first negative electrode film layer is granular, and its volume average particle size Dv50 is 7.8 μm to 14.3 μm, and optionally 7.8 μm to 11.3 μm. When the volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is within the above range, the solid-phase transmission path of lithium ions can be shortened, thereby improving fast charging performance.

[0449] Illustratively, the carbon-based material of the second negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the first negative electrode film layer includes artificial graphite.

[0450] In some embodiments, the negative electrode film layer may further optionally include a negative electrode conductive agent. The present application does not particularly limit the type of negative electrode conductive agent. For example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the weight content of the negative electrode conductive agent is ≤5% based on the total weight of the negative electrode film layer.

[0451] In some embodiments, the negative electrode film layer may further include a negative electrode binder. In some embodiments, the negative electrode binder has a mass content of ≤5% based on the total weight of the negative electrode film layer.

[0452] In some embodiments, the negative electrode film layer may also optionally include other additives. Examples of these additives include thickeners, dispersants, and the like, such as sodium carboxymethylcellulose (CMC-Na) and PTC thermistor materials. In some embodiments, the weight content of these additives is ≤ 2% based on the total weight of the negative electrode film layer.

[0453] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0454] In some embodiments, the ratio of the thickness of the negative electrode film layer on one side to the thickness of the negative electrode current collector is 8 to 14, such as 8, 9, 10, 11, 12, 13, 14, or a range consisting of any two of the foregoing values. Alternatively, the ratio of the thickness of the negative electrode film layer on one side to the thickness of the negative electrode current collector is 10 to 12.

[0455] When the ratio of the thickness of the single-side negative electrode film layer to the thickness of the negative electrode current collecting portion is within the above range, the fast charging capability and energy density of the battery cell can be improved.

[0456] In some embodiments, the thickness of the negative electrode current collector is 5 μm to 10 μm, optionally 6 μm to 8 μm. For example, the thickness of the negative electrode current collector is 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, or a range consisting of any two of the above values.

[0457] When the thickness of the negative electrode current collecting portion is within the above range, the negative electrode current collecting portion has a relatively excellent current flow capacity and can enable the battery cell to have a relatively high energy density.

[0458] In the embodiment of the present application, the thickness of the negative electrode current collector has a meaning well known in the art and can be detected using equipment and methods well known in the art. For example, a solvent is used to wash away the film layer on the surface of the negative electrode current collector, and the thickness of the negative electrode current collector is measured with a micrometer.

[0459] The negative electrode film layer is typically formed by coating the negative electrode slurry onto the negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing the negative electrode active material, an optional conductive agent, an optional binder, and other optional additives in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0460] The negative electrode sheet does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of the embodiments of the present application further includes a negative conductive layer sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode sheet of the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0461] [Isolator]

[0462] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode sheet and the negative electrode sheet.

[0463] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0464] As an example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes. The surface of the separator can also be coated with an inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating.

[0465] In some embodiments, the volumetric energy density of the battery cell is between 385Wh / L and 450Wh / L. For example, the volumetric energy density of the battery cell is 385Wh / L, 390Wh / L, 400Wh / L, 410Wh / L, 420Wh / L, 430Wh / L, 450Wh / L, or a range consisting of any two of these values. The volumetric energy density of the battery cell is relatively high.

[0466] In the embodiments of the present application, the volume energy density of a battery cell has a meaning well known in the art and can be detected using equipment and methods well known in the art. For example, the battery charging upper limit voltage is 3.65V and the battery discharge cut-off voltage is 2.0V.

[0467] Place the battery cell at 25°C, charge at a constant current of 0.33C to 3.65V, then charge at a constant voltage to 0.05C, and discharge at a constant current of 0.33C to 2.0V. Record the discharge capacity A0 at this time, unit: Ah. Use calipers to measure the length, width, and height of the battery cell (generally calculated based on the battery casing size, excluding the electrode terminal height and the insulating film outside the casing), calculate the volume of the single battery V0, unit L, and the volume energy density of the battery cell VED = (A0 × discharge platform voltage) / V0, unit Wh / L.

[0468] In some embodiments, the volumetric energy density of a battery cell can be adjusted by the following optional methods:

[0469] From the perspective of active materials, high specific capacity positive and negative active materials can be used. For example, for positive electrode active materials, lithium phosphate materials with higher gram capacity can be used, for example, physically mixing positive electrode active materials with higher gram capacity, such as ternary materials, to improve energy density; for negative electrode active materials, graphite with higher gram capacity can be used, for example, physically mixing negative electrode active materials with higher gram capacity, such as silicon-based materials;

[0470] From the perspective of electrolyte, reduce the electrolyte injection volume or use electrolyte that supports higher energy density;

[0471] From the perspective of electrode design, the compaction density and coating weight of the positive electrode or negative electrode can be adjusted, or the thickness of the positive electrode current collector or negative electrode current collector can be adjusted;

[0472] In terms of the isolation film, the thickness of the isolation film can be adjusted;

[0473] In terms of structural design, the first step is to reduce the proportion of inactive materials such as battery components. For example, by making the battery casing thinner while ensuring its safety and mechanical properties, more active materials can be accommodated in the same space, thereby increasing energy density. For example, the space occupied by the electrode assembly within the casing cavity can be adjusted.

[0474] Example

[0475] The following examples describe the disclosure of the present invention in more detail. These examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present invention will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0476] Example 1

[0477] 1. Preparation of positive electrode sheet

[0478] The positive electrode sheet includes a positive electrode current collecting portion and a positive electrode film layer arranged on both sides of the positive electrode current collecting portion. The positive electrode current collecting portion is an aluminum foil with a thickness of 13.5 μm.

[0479] The positive electrode film layer includes lithium-containing phosphate, binder polyvinylidene fluoride (PVDF) and conductive agent acetylene black in a mass ratio of 96:2:2. The positive electrode film layer is formed by evenly coating the positive electrode slurry (the solvent is N-methylpyrrolidone NMP) on both sides of the positive electrode current collecting part, and then drying and cold pressing.

[0480] Lithium-containing phosphates include lithium iron phosphate.

[0481] The single-sided coating weight of the positive electrode film is 300mg / 1540.25mm 2 .

[0482] The length of the positive electrode film layer is 500 mm, and the ratio of the length to the width of the positive electrode film layer is 5.25.

[0483] 2. Preparation of negative electrode sheet

[0484] The negative electrode plate includes a negative electrode current collecting portion and a negative electrode film layer arranged on both sides of the negative electrode current collecting portion. The negative electrode current collecting portion is a copper foil with a thickness of 6 μm.

[0485] The negative electrode film layer is formed by uniformly coating the negative electrode slurry (the solvent is deionized water) on the surface of the negative electrode current collector, drying it, and cold pressing it.

[0486] The single-sided coating weight of the negative electrode film is 130mg / 1540.25mm 2 .

[0487] The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode film layer is located on the surface of the negative electrode current collecting portion, and the second negative electrode film layer is located on the surface of the first negative electrode film layer.

[0488] The first negative electrode film layer includes a carbon-based material with a mass ratio of 96.5:1:1.5:1, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose. The carbon-based material of the first negative electrode film layer includes artificial graphite and natural graphite with a mass ratio of 1:1, and the volume average particle size of the carbon-based material is 9.0 μm.

[0489] The second negative electrode film layer includes a carbon-based material, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose in a mass ratio of 96.5:1:1.5:1. The carbon-based material of the second negative electrode film layer includes artificial graphite, and the volume average particle size of the carbon-based material is 8.0 μm.

[0490] 3. Isolation parts

[0491] The separator includes a base film, which is a 7 μm polyethylene film layer with a porosity of 42%.

[0492] 4. Preparation of electrolyte

[0493] The electrolyte includes an organic solvent, lithium salt and additives.

[0494] The organic solvent includes 10% chain carboxylic acid ester solvent (ethyl acetate) and 75% carbonate solvent (diethyl carbonate, dimethyl carbonate, ethylene carbonate in a mass ratio of 1:1:1). The mass content of each component in the organic solvent is calculated based on the mass of the electrolyte.

[0495] Based on the mass of the electrolyte, the mass content of the additive is 1.5%, which includes vinylene carbonate VC.

[0496] The lithium salt includes 8.5% lithium hexafluorophosphate LiPF6 and 5% lithium bis(fluorosulfonyl)imide.

[0497] The conductivity of the electrolyte at room temperature is 12 mS / cm.

[0498] 5. Preparation of battery cells

[0499] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive electrode sheet and the negative electrode sheet to serve as an isolation, to obtain a laminated electrode assembly. The electrode assembly is placed in a housing assembly, dried, and then injected with electrolyte. After vacuum packaging, standing, forming, shaping, and other processes, a battery cell is obtained. The compaction density of the positive electrode film layer of the battery cell at 0% SOC is 2.5 g / cm 3 The compaction density of the negative electrode film at 0% SOC is 1.45g / cm 3 ,

[0500] The housing assembly further includes a housing, an end cap, a positive terminal, and a negative terminal. The housing accommodates the electrode assembly and the electrolyte. The housing includes an opening, the end cap is covered with the opening, and the positive terminal and the negative terminal are provided on the end cap.

[0501] The length of the battery cell is 525 mm, the thickness of the battery cell is 10 mm, the width is 100 mm, and the ratio of length to thickness is 52.5.

[0502] Comparative Examples 1 to 3

[0503] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the minimum cross-sectional areas of the positive terminal and the negative terminal were adjusted. The parameters are shown in Table 1.

[0504] Among them, Comparative Examples 1 and 2 also adjusted the size of the battery cells. The length to width ratio of the positive electrode plate of Comparative Example 1 was 2; the length of the battery cell was 225 mm, the thickness of the battery cell was 10 mm, the width was 100 mm, and the length to thickness ratio was 22.5.

[0505] The ratio of the length to the width of the positive electrode sheet of Comparative Example 2 is 8; the length of the battery cell is 825 mm, the thickness of the battery cell is 10 mm, the width is 100 mm, and the ratio of the length to the thickness is 82.5.

[0506] Example 2-1 to Example 2-3

[0507] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the minimum cross-sectional areas of the positive terminal and the negative terminal were adjusted. The parameters are shown in Table 1.

[0508] Example 3

[0509] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the number of positive terminals and negative terminals was adjusted. The parameters are shown in Table 1.

[0510] Example 4-1 and Example 4-2

[0511] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the welding areas of the positive terminal and the positive electrode tab were adjusted. The parameters are shown in Table 1.

[0512] Table 1

[0513]

[0514] In Table 1,

[0515] x1 represents the number of positive terminals;

[0516] x2 represents the number of negative terminals;

[0517] S1 represents the minimum cross-sectional area of ​​a single positive terminal perpendicular to its own thickness direction, and its unit is mm 2 ;

[0518] S2 represents the minimum cross-sectional area of ​​a single negative terminal perpendicular to its own thickness direction, and its unit is mm 2 ;

[0519] M1 represents the welding area of ​​all positive terminals and positive pole ears, and its unit is mm 2 ;

[0520] M2 represents the welding area of ​​all negative terminals and negative pole ears, and its unit is mm 2 ;

[0521] In Example 1, the size T1 of the first protrusion of the positive terminal is 2 mm, and the size T of the second protrusion of the negative terminal is 2 mm. Figure 9 As shown, the two positive terminals are respectively arranged on both sides of the electrode assembly along the length direction of the battery cell, and the two negative terminals are respectively arranged on both sides of the electrode assembly along the length direction of the battery cell.

[0522] Except for Example 3, the other examples and comparative examples adopted the same arrangement of electrode terminals as that of Example 1.

[0523] In Example 3, Figure 11 As shown, there is one positive terminal, which is arranged on one side of the electrode assembly along the length direction of the battery cell, and one negative terminal, which is arranged on the other side of the electrode assembly along the length direction of the battery cell.

[0524] Performance Testing

[0525] 1. DC internal resistance DCR test of battery cells

[0526] You can refer to the methods in GB / T 31467 "Performance test specification for high-power lithium-ion power batteries for HEV".

[0527] For example, at 25°C, charge the battery cell to 3.65V at a constant current of 0.33C, let it stand for 1 min, then charge it to 3.65V at a constant current of 0.05C, let it stand for 30 min, and discharge it to 2.5V at a constant current of 0.33C. Record the discharge capacity A0 at this time in Ah, and then charge it at a constant current of 0.33C for 0.5A0Ah, and adjust the SOC to 50%.

[0528] After the battery cell is placed at 25 ℃ for 2 hours, it is discharged at a constant current of 4C for 10 seconds and the ∆U 放电 , ∆I 放电 , the discharge DCR data of lithium-ion batteries is calculated by the following formula, R 放电 =∆U 放电 / ∆I 放电 ,

[0529] Where ∆U 放电 Indicates the voltage change within 10s after the discharge starts, ∆I 放电 Indicates the current value within 10 seconds after the start of discharge.

[0530] The test results are shown in Table 2.

[0531] Table 2

[0532]

[0533] In Table 2,

[0534] E represents the single cell energy of the battery cell, and its unit is Wh. The single cell energy E of each embodiment and comparative example is 225Wh.

[0535] In Comparative Examples 1 and 3, the flow area of ​​the electrode terminals is relatively small, so when the flow capacity is insufficient, the internal resistance of the battery cell is large, which is not conducive to fast charging at high energy density.

[0536] Although the electrode terminal in Comparative Example 2 has a strong overcurrent capacity, the ratio of the length to the width of the positive electrode plate in Comparative Example 2 is too large, and the length of the battery cell is relatively strong, which makes the migration path of electrons in the length direction of the positive electrode plate longer and the internal resistance larger, which is not conducive to fast charging at high energy density.

[0537] The embodiment of the present application adjusts the flow area of ​​the electrode terminal so that (x1×S1+x2×S2) / E is greater than or equal to 0.4, thereby improving the flow capacity of the electrode terminal and reducing the internal resistance of the battery cell, which is beneficial to improving the fast charging capability of high energy density battery cells.

[0538] In Example 1, Example 2-1 to Example 2-3, the larger the flow area of ​​the electrode terminal, the stronger the flow capacity, and the more conducive to reducing the internal resistance of the battery cell. However, the flow area of ​​the electrode terminal is limited by the assembly space, making (x1×S1+x2×S2) / E less than or equal to 1.4.

[0539] Example 3 uses one negative terminal, while Example 2-3 uses two negative terminals. The flow area of ​​the negative terminal in Example 3 is substantially the same as the flow area of ​​each negative terminal in Example 2-3. In other words, the flow area of ​​the negative terminal in Example 3 is less than the total flow area of ​​the two negative terminals in Example 2-3. The flow capacity of the negative terminal in Example 3 is less than the total flow capacity of the negative terminals in Example 2-3, and the internal resistance of Example 3 is relatively high. However, because Example 3 uses one positive terminal, the flow area of ​​one positive terminal is substantially the same as the total flow area of ​​the two positive terminals in Example 2-3. This results in substantially the same flow capacity of the positive terminals in Example 3 and Example 2-3. The positive terminal has a stronger flow capacity, which in turn results in a relatively stronger flow capacity for the battery cell as a whole, facilitating rapid charging.

[0540] In Example 1, Example 4-1 and Example 4-2, the flow capacity between the electrode terminal and the pole ear is adjusted by adjusting the weld area between the electrode terminal and the pole ear. As the weld area increases, the flow capacity becomes stronger and the internal resistance becomes smaller, which is more conducive to improving the fast charging capability of high energy density battery cells.

[0541] Example 5-1 and Example 5-2

[0542] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the size of the battery cell was adjusted.

[0543] The test results are shown in Table 3.

[0544] Table 3

[0545]

[0546] In each embodiment and comparative example, the width of the battery cell is 100 mm, the thickness is 10 mm, and the ratio of the width to the thickness is 10.

[0547] In Comparative Example 1, not only is the overcurrent capacity of the electrode terminal insufficient, but also the energy density of the battery cell is low due to the short size of the battery cell.

[0548] Compared with Comparative Example 2, the aspect ratio of the positive electrode film layer in the embodiment of the present application is 4 to 7, and the size of the battery cell is within an appropriate range, which can enable the battery cell to have a relatively high energy density; and combined with the appropriate number and appropriate position setting of the electrode terminals, for example, the two positive terminals are respectively arranged on both sides of the electrode assembly along the length direction, which can effectively shorten the electron transmission path, improve the current flow capacity, reduce the internal resistance, and enhance the fast charging capability of the battery cell.

[0549] Example 6-1 to Example 6-2

[0550] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the coating weight on each side of the positive and negative electrode films was adjusted.

[0551] Example 6-3 to Example 6-4

[0552] A battery cell was prepared using a method similar to that of Example 1. The difference from Example 1 was that the compaction density of the positive and negative electrode film layers was adjusted.

[0553] The test results are shown in Table 4.

[0554] Table 4

[0555]

[0556] The single-sided coating weight of the positive and negative electrode film layers has been adjusted. When the single-sided coating weight is relatively high, it is beneficial to increase the single-cell energy of the battery cell and improve the energy density; however, due to the increase in the migration path of lithium ions in the positive and negative electrode film layers, the DCR is slightly deteriorated.

[0557] The single-side coating weight of the positive and negative electrode films of Example 6-1 and Example 6-2 is within an appropriate range. For example, the single-side coating weight of the positive electrode film is 250 mg / 1540.25 mm 2 Up to 330mg / 1540.25mm 2 The single-sided coating weight of the negative electrode film is 120mg / 1540.25mm 2 Up to 180mg / 1540.25mm 2 , which enables the battery cells to have both higher single-cell energy and lower DCR, and is conducive to improving the fast charging performance and energy density of the battery cells.

[0558] The compaction density of the positive and negative electrode film layers has been adjusted. When the compaction density is relatively high, it is beneficial to increase the single cell energy of the battery cell and improve the energy density; however, since the migration resistance of lithium ions in the positive and negative electrode film layers may increase, the DCR is slightly deteriorated.

[0559] The single-sided coating weight of the positive and negative electrode films of Example 6-3 and Example 6-4 is within an appropriate range. For example, the compaction density of the positive electrode film is 2.30 g / cm 3 to 2.70g / cm 3 The compaction density of the negative electrode film is 1.30g / cm 3 Up to 1.65g / cm 3 , which enables the battery cells to have both higher single-cell energy and lower DCR, and is conducive to improving the fast charging performance and energy density of the battery cells.

[0560] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the embodiments of the present application, and that changes, substitutions, and modifications may be made to the embodiments without departing from the spirit, principles, and scope of the embodiments of the present application.

Claims

1. A battery cell, characterized in that: include: An electrode assembly comprising a plurality of first pole sheets and a plurality of second pole sheets, wherein the first pole sheets and the second pole sheets are stacked along the thickness direction of the battery cell, and each of the first pole sheet and the second pole sheet comprises a coating portion and a pole ear portion, wherein the coating portion is provided with an active material layer, and the pole ear portion is connected to the coating portion and extends out of the coating portion; as well as A housing assembly includes a housing and a terminal assembly disposed on the housing, wherein the housing accommodates the electrode assembly, the terminal assembly includes at least one first electrode terminal and at least one second electrode terminal, the first electrode terminal is connected to the pole ear portion of the first pole piece, and the second electrode terminal is connected to the pole ear portion of the second pole piece. Wherein, one of the first electrode sheet and the second electrode sheet is a positive electrode sheet, and the other is a negative electrode sheet, and the active material layer of the positive electrode sheet includes a lithium-containing phosphate with an olivine structure; The size of the coating portion of the positive electrode sheet along the length direction of the battery cell is a first size, the size of the coating portion of the positive electrode sheet along the width direction of the battery cell is a second size, and a ratio of the first size to the second size is 4 to 7; The battery cell satisfies: (x1×S1+x2×S2) / E is 0.4 to 1.4, x1 represents the number of the first electrode terminals; x2 represents the number of the second electrode terminals; S1 represents the minimum cross-sectional area of ​​a single first electrode terminal perpendicular to its own thickness direction, and its unit is mm 2 ; S2 represents the minimum cross-sectional area of ​​a single second electrode terminal perpendicular to its own thickness direction, and its unit is mm 2 ; E represents the single cell energy of the battery cell, and its unit is Wh; The single-side coating weight of the active material layer of the negative electrode plate is 120 mg / 1540.25 mm 2 Up to 180mg / 1540.25mm 2 .

2. The battery cell according to claim 1, wherein: S1 is from 15 to 60; and / or S2 is from 15 to 60.

3. The battery cell according to claim 1 or 2, characterized in that: x1 is 1 to 4; and / or x2 is 1 to 4.

4. The battery cell according to any one of claims 1 to 2, characterized in that: The battery cell also satisfies: M1 / E is 0.2 to 0.6; M1 represents the area of ​​the first connecting area, and its unit is mm 2 The first connection area is the area where the at least one first electrode terminal is connected to the ear portion of the first electrode piece; and / or The battery cell also satisfies: M2 / E is 0.2 to 0.6, M2 represents the area of ​​the second connecting area, and its unit is mm 2 ; The second connection area is the area where the at least one second electrode terminal is connected to the pole ear portion of the second pole piece.

5. The battery cell according to claim 4, characterized in that M1 is 60 to 120; and / or M2 is 60 to 120.

6. The battery cell according to any one of claims 1 to 2, characterized in that: E is 170 to 480.

7. The battery cell according to any one of claims 1 to 2, characterized in that: The first electrode terminal is disposed on at least one side of the electrode assembly along the length direction; and / or The second electrode terminal is disposed on at least one side of the electrode assembly along the length direction.

8. The battery cell according to any one of claims 1 to 2, characterized in that: There are at least two first electrode terminals, and the at least two first electrode terminals are respectively arranged on both sides of the electrode assembly along the length direction; and / or There are at least two second electrode terminals, and the at least two second electrode terminals are respectively arranged on both sides of the electrode assembly along the length direction.

9. The battery cell according to any one of claims 1 to 2, characterized in that: The housing includes a shell and an end cover, the shell accommodates the electrode assembly, the shell includes an opening, the end cover covers the opening, and the first electrode terminal is disposed on the end cover; The first electrode terminal includes: a first main body, disposed on the housing and passing through the end cover; as well as The first protrusion is provided on the first main body and protrudes from the first main body to be connected to a side of the end cover facing the electrode assembly.

10. The battery cell according to claim 9, characterized in that In a direction from the first main body to the first protrusion, a size of the first protrusion is 1.5 mm to 30 mm.

11. The battery cell according to claim 9, characterized in that The first main body and the first protruding portion are an integrated structure.

12. The battery cell according to claim 9, characterized in that The first main body is disposed on the end cover and passes through the end cover. The ratio of the dimension of the first main body along the thickness direction of the battery cell to the dimension of the end cover along the thickness direction of the battery cell is 0.20 to 0.

40.

13. The battery cell according to claim 9, characterized in that The shell assembly also includes a first conductive fixing member, at least part of which is located on a side of the end cover away from the electrode assembly. The first conductive fixing member is arranged around the outside of the first main body and fixedly connects the first main body and the end cover.

14. The battery cell according to claim 13, characterized in that A ratio of a dimension of the first conductive fixing member along a thickness direction of the battery cell to a dimension of the end cover along the thickness direction of the battery cell is 0.40 to 0.

80.

15. The battery cell according to any one of claims 1 to 2, characterized in that: The pole ear portion of the first pole piece is provided on at least one side of the coating portion along the first direction, and the first pole piece satisfies: n*W1 / W2 is 0.5 to 1.0; n represents the number of all the tabs located on the same side of the coating portion; W1 represents the average size of the tab portion along the second direction, one of the first direction and the second direction is parallel to the length direction of the battery cell, and the other is parallel to the width direction of the battery cell; W2 represents the dimension of the coating portion along the second direction.

16. The battery cell according to claim 15, characterized in that The first direction is parallel to the length direction of the battery cell.

17. The battery cell according to any one of claims 1 to 2, characterized in that: There are at least two pole lugs in the first pole piece located on the same side of the coating portion.

18. The battery cell according to claim 16, characterized in that The first pole piece has a plurality of pole ear portions, and the plurality of pole ear portions of the first pole piece are located on both sides of the coating portion along the first direction; or All the pole lug portions of the first pole piece are located on the same side of the coating portion along the first direction.

19. The battery cell according to any one of claims 1 to 2, characterized in that: The ratio of the length of the battery cell to the thickness of the battery cell is 40 to 70; and / or A ratio of the width of the battery cell to the thickness of the battery cell is 3 to 15.

20. The battery cell according to any one of claims 1 to 2, characterized in that: The thickness of the battery cell is 10 mm to 30 mm.

21. The battery cell according to any one of claims 1 to 2, characterized in that: The olivine-structured lithium-containing phosphate includes lithium iron phosphate.

22. The battery cell according to any one of claims 1 to 2, characterized in that: The single-side coating weight of the active material layer of the positive electrode sheet is 250 mg / 1540.25 mm 2 Up to 330mg / 1540.25mm 2 and / or The battery cell is at 0% state of charge, and the compaction density of the active material layer of the positive electrode sheet is 2.30 g / cm 3 to 2.70g / cm 3 .

23. The battery cell according to any one of claims 1 to 2, characterized in that: The battery cell is at 0% state of charge, and the compaction density of the active material layer of the negative electrode plate is 1.30 g / cm 3 Up to 1.65g / cm 3 .

24. The battery cell according to any one of claims 1 to 2, characterized in that: The coating portion of the negative electrode sheet includes a negative electrode current collecting portion and a negative electrode film layer provided on at least one side of the negative electrode current collecting portion, wherein the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes: A first negative electrode film layer is provided on the surface of the negative electrode current collecting portion; and A second negative electrode film layer is connected to a side of the first negative electrode film layer away from the negative electrode current collecting portion, The volume average particle size Dv50 of the carbon-based material of the first negative electrode film layer is greater than or equal to the volume average particle size Dv50 of the carbon-based material of the second negative electrode film layer.

25. The battery cell according to claim 24, characterized in that The carbon-based material of the first negative electrode film layer is in a granular form, and its volume average particle size Dv50 is 9.5 μm to 18.5 μm; and / or The carbon-based material of the second negative electrode film layer is granular, and its volume average particle size Dv50 is 7.8 μm to 14.3 μm.

26. The battery cell according to claim 24, characterized in that The carbon-based material of the first negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer includes artificial graphite.

27. The battery cell according to any one of claims 1 to 2, characterized in that: The invention also includes an electrolyte having an electrical conductivity of 10 mS / cm to 13 mS / cm at room temperature.

28. The battery cell according to claim 27, characterized in that The electrolyte includes an organic solvent, and the organic solvent includes a chain carboxylate solvent. The mass content of the chain carboxylate solvent is 5% to 30% based on the mass of the electrolyte.

29. The battery cell according to claim 27, characterized in that The electrolyte includes a lithium salt, wherein the lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide. Based on the mass of the electrolyte, the ratio of the mass content of the lithium hexafluorophosphate to the mass content of the lithium bis(fluorosulfonyl)imide is 0.5 to 4.

30. A battery device, characterized in that: The invention comprises the battery cell according to any one of claims 1 to 29.

31. An electrical device, characterized in that: Comprising the battery device of claim 30.

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