Battery cell, battery device, and electric device

Abstract

The utility model discloses a battery monomer, a battery device and a power utilization device. The battery monomer comprises a shell, a positive electrode lead-out part, a negative electrode lead-out part and an electrode assembly. The positive electrode lead-out part and the negative electrode lead-out part are arranged on the housing. The electrode assembly is housed within the housing. The electrode assembly comprises a positive plate and a negative plate, the positive plate comprises a positive main body part and a positive lug, and the negative plate comprises a negative main body part and a negative lug. And the conductivity of the negative tab is greater than that of the positive tab. The plurality of positive tabs are welded to the positive lead-out part and form a first welding mark, and the plurality of negative tabs are welded to the negative lead-out part and form a second welding mark. The positive tab comprises a positive connecting part, one end of the positive connecting part is connected to the positive main body part, and the other end is connected to the first welding mark; the negative tab comprises a negative connecting part, one end of the negative connecting part is connected to the negative main body part, and the other end is connected to the second welding mark.

Description

Technical Field

[0001] The present application relates to the field of batteries, and particularly to a battery cell, a battery device, and an electrical device. Background Art

[0002] Battery cells are widely used in electronic devices, such as mobile phones, laptop computers, battery-powered vehicles, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] In the development of battery technology, how to improve the cycle performance of battery cells is a research direction in battery technology. Summary of the Utility Model

[0004] The present application provides a battery cell, a battery device, and an electrical device, which can improve the cycle performance.

[0005] In a first aspect, the present application provides a battery cell, which includes a housing, a positive electrode lead-out portion, a negative electrode lead-out portion, and an electrode assembly. The positive electrode lead-out portion and the negative electrode lead-out portion are provided on the housing. The electrode assembly is accommodated in the housing. The electrode assembly includes a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive electrode main body portion and a positive electrode tab. The positive electrode main body portion is provided with a positive electrode active material layer. The positive electrode tab extends from the edge of the positive electrode main body portion. The negative electrode plate includes a negative electrode main body portion and a negative electrode tab. The negative electrode main body portion is provided with a negative electrode active material layer. The negative electrode tab extends from the edge of the negative electrode main body portion. The conductivity of the negative electrode tab is greater than that of the positive electrode tab. A plurality of positive electrode tabs are welded to the positive electrode lead-out portion and form a first welding mark. A plurality of negative electrode tabs are welded to the negative electrode lead-out portion and form a second welding mark. The positive electrode tab includes a positive electrode connection portion. One end of the positive electrode connection portion is connected to the positive electrode main body portion, and the other end is connected to the first welding mark. The negative electrode tab includes a negative electrode connection portion. One end of the negative electrode connection portion is connected to the negative electrode main body portion, and the other end is connected to the second welding mark. The sum of the minimum current-carrying cross-sectional areas of the positive electrode connection portions of a plurality of positive electrode tabs is S1; the sum of the minimum current-carrying cross-sectional areas of the negative electrode connection portions of a plurality of negative electrode tabs is S2; S1 is greater than S2.

[0006] In the embodiments of the present application, setting S1 to be greater than S2 can reduce the difference in current-carrying capacity between a plurality of positive electrode connection portions and a plurality of negative electrode connection portions caused by different conductivities, reduce the temperature difference between the positive electrode connection portion and the negative electrode connection portion, and further reduce the temperature difference between the positive electrode main body portion and the negative electrode main body portion, thereby improving the cycle performance and cycle life of the battery cell.

[0007] In some embodiments, the conductivity of the positive electrode tab is σ c , and the conductivity of the negative electrode tab is σ a . S1 / S2≥σ a / σ cSet S1 and S2 according to the conductivity of the positive tab and the conductivity of the negative tab, which can further reduce the difference in overcurrent capacity between the multiple positive connection parts and the multiple negative connection parts, reduce the temperature difference between the positive connection part and the negative connection part, and further reduce the temperature difference between the positive main body part and the negative main body part, improving the cycle performance and cycle life of the battery cell.

[0008] In some embodiments, the total volume of the multiple positive connection parts is greater than or equal to the total volume of the multiple negative connection parts. By increasing the total volume of the multiple positive connection parts, the overcurrent capacity of the multiple positive connection parts can be improved, and the difference in overcurrent capacity between the multiple positive connection parts and the multiple negative connection parts can be reduced.

[0009] In some embodiments, the positive connection part has two first surfaces opposite to each other along its own thickness direction, and the area of the first surface is S c ; the negative connection part has two second surfaces opposite to each other along its own thickness direction, and the area of the second surface is S a . The thermal conductivity of the negative tab is greater than that of the positive tab, and S c is greater than S a .

[0010] Compared with the negative tab, the positive tab has a poor heat conduction ability; in the embodiments of the present application, S c is greater than S a , so as to increase the heat dissipation area of the positive tab, reduce the temperature rise of the positive tab during overcurrent, reduce the temperature difference between the positive connection part and the negative connection part, improve the temperature consistency, and improve the cycle performance of the battery cell.

[0011] In some embodiments, the minimum width of the positive connection part is greater than the minimum width of the negative connection part. Compared with the negative connection part, the positive connection part can have a larger width, thereby increasing the overcurrent cross-sectional area and heat dissipation area of the positive connection part, reducing the difference in overcurrent capacity between the positive connection part and the negative connection part, reducing the temperature difference between the positive connection part and the negative connection part, and improving the cycle performance of the battery cell.

[0012] In some embodiments, the thickness of the positive tab is greater than the thickness of the negative tab. Compared with the negative tab, the positive tab can have a larger thickness, thereby increasing the overcurrent cross-sectional area and heat dissipation area of the positive connection part, reducing the difference in overcurrent capacity between the positive connection part and the negative connection part, reducing the temperature difference between the positive connection part and the negative connection part, and improving the cycle performance of the battery cell.

[0013] In some embodiments, the number of positive tabs is greater than the number of negative tabs. Embodiments of the present application can add a positive connection part, reduce the difference in overcurrent capacity between the plurality of positive connection parts and the plurality of negative connection parts, reduce the temperature difference between the positive connection part and the negative connection part, and further reduce the temperature difference between the positive main body part and the negative main body part, thereby improving the cycle performance and cycle life of the battery cell.

[0014] In some embodiments, the area of the first welding mark is greater than the area of the second welding mark. Embodiments of the present application can increase the overcurrent cross-sectional area of the first welding mark, reduce the difference in overcurrent capacity between the first welding mark and the second welding mark, increase the heat dissipation area of the first welding mark, reduce the temperature difference between the first welding mark and the second welding mark, and improve the cycle performance and cycle life of the battery cell.

[0015] In some embodiments, the positive electrode lead-out part includes a positive terminal and a positive electrode adapter plate. The positive electrode adapter plate is welded to a plurality of positive tabs and forms a first welding mark. The positive terminal is arranged on the outer shell, and the positive terminal is welded to the positive electrode adapter plate and forms a third welding mark. The negative electrode lead-out part includes a negative terminal and a negative electrode adapter plate. The negative electrode adapter plate is welded to a plurality of negative tabs and forms a second welding mark. The negative terminal is arranged on the outer shell, and the negative terminal is welded to the negative electrode adapter plate and forms a fourth welding mark.

[0016] In some embodiments, the area of the third welding mark is greater than the area of the fourth welding mark. Embodiments of the present application can further improve the overcurrent capacity on the positive electrode overcurrent chain of the battery cell, reduce the difference in overcurrent capacity between the positive and negative electrodes, improve the overcurrent consistency, and improve the cycle performance of the battery cell.

[0017] In some embodiments, the minimum overcurrent distance between the first welding mark and the third welding mark is less than the minimum overcurrent distance between the second welding mark and the fourth welding mark. Embodiments of the present application can shorten the conduction path on the positive electrode overcurrent chain of the battery cell, reduce the resistance, reduce the difference in overcurrent capacity between the positive and negative electrodes, and improve the overcurrent consistency.

[0018] In some embodiments, the volume of the positive electrode adapter plate is greater than or equal to the volume of the negative electrode adapter plate to enhance the overcurrent capacity of the positive electrode adapter plate and increase the heat dissipation area of the positive electrode adapter plate.

[0019] In some embodiments, the minimum overcurrent cross-sectional area of the positive terminal is greater than or equal to the minimum overcurrent cross-sectional area of the negative terminal. By increasing the overcurrent area of the positive terminal, embodiments of the present application can reduce the difference in overcurrent capacity between the positive terminal and the negative terminal and reduce the temperature difference between the positive terminal and the negative terminal during overcurrent.

[0020] In some embodiments, the material of the positive tab is aluminum, and the material of the negative tab is copper. Both copper and aluminum have high thermal conductivity and electrical conductivity. Using aluminum positive tabs and copper negative tabs can improve the overcurrent capacity, reduce the temperature rise of the electrode assembly, and improve the cycle performance.

[0021] In some embodiments, the positive electrode sheet further includes a conductive layer coated on the positive electrode connection portion. By coating the conductive layer, the current-carrying area can be increased, and heat generation at the positive electrode connection portion can be reduced.

[0022] In some embodiments, the average charging rate of the battery cell is K, satisfying K≥2. The battery cell has the ability of fast charging, which can save charging time and improve the user experience.

[0023] In a second aspect, an embodiment of the present application provides a battery device, which includes a plurality of battery cells provided in any of the first aspect embodiments.

[0024] In some embodiments, the battery device further includes a heat exchange member for exchanging heat with the positive electrode lead-out portion.

[0025] In a third aspect, an embodiment of the present application provides an electrical device, which includes the battery device provided in any of the second aspect embodiments, and the battery device is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The features, advantages, and technical effects of the exemplary embodiments of the present application will be described below with reference to the drawings.

[0027] Figure 1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0028] Figure 2 is a schematic diagram of a battery device provided in some embodiments of the present application;

[0029] Figure 3 is an exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0030] Figure 4 is a schematic diagram of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0031] Figure 5 is a schematic diagram of a positive electrode sheet of a battery cell in a flattened state provided in some embodiments of the present application;

[0032] Figure 6 is Figure 5 a cross-sectional schematic diagram taken along the A-A direction;

[0033] Figure 7 is a schematic diagram of a negative electrode sheet of a battery cell in a flattened state provided in some embodiments of the present application;

[0034] Figure 8 is Figure 7 a cross-sectional schematic diagram taken along the B-B direction;

[0035] Figure 9A cross-sectional schematic diagram of a battery cell provided by some embodiments of the present application;

[0036] Figure 10 Is an enlarged schematic diagram at box C;

[0037] Figure 11 Is Figure 9 An enlarged schematic diagram at box D;

[0038] Figure 12 Another cross-sectional schematic diagram of a battery cell provided by some embodiments of the present application;

[0039] Figure 13 A schematic diagram of a battery cell during the assembly process provided by some embodiments of the present application;

[0040] Figure 14 Is Figure 5 An enlarged schematic diagram at the circular frame;

[0041] Figure 15 Is Figure 7 An enlarged schematic diagram at the circular frame;

[0042] Figure 16 A cross-sectional schematic diagram of the positive electrode plate of a battery cell provided by some other embodiments of the present application;

[0043] Figure 17 A schematic diagram of a battery device provided by some other embodiments of the present application.

[0044] The description of the reference numerals is as follows:

[0045] 1, vehicle; 2, battery device; 3, controller; 4, motor; 5, box body; 5a, first box body part; 5b, second box body part; 6, battery cell; 7, heat exchange member;

[0046] 10, electrode assembly; 10a, electrode main body;

[0047] 11, positive electrode plate; 111, positive electrode main body part; 112, positive electrode tab; 1121, positive electrode connection part; 1121a, first surface; 1122, first positive electrode part; 1123, second positive electrode part; 1124, positive electrode welding area; 113, positive electrode active material layer; 114, positive electrode current collector; 115, positive electrode coating area; 116, conductive layer;

[0048] 12, negative electrode plate; 121, negative electrode main body part; 122, negative electrode tab; 1221, negative electrode connection part; 1221a, second surface; 1222, first negative electrode part; 1223, second negative electrode part; 1224, negative electrode welding area; 123, negative electrode active material layer; 124, negative electrode current collector; 125, negative electrode coating area;

[0049] 13. Isolation member;

[0050] 20. Outer shell; 21. Housing; 22. End cap; 221. Positive electrode lead-out hole; 222. Negative electrode lead-out hole;

[0051] 30. Positive electrode lead-out part; 31. Positive electrode terminal; 32. Positive electrode adapter piece;

[0052] 40. Negative electrode lead-out part; 41. Negative electrode terminal; 42. Negative electrode adapter piece;

[0053] 50. First insulating member; 60. First fixing member; 70. Second insulating member; 80. Second fixing member;

[0054] P1. First welding mark; P2. Second welding mark; P3. Third welding mark; P4. Fourth welding mark;

[0055] X. Second direction; Y. Third direction; Z. First direction. Detailed implementation manners

[0056] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts fall within the scope of protection of the present application.

[0057] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification, claims and drawings of the present application are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification, claims or drawings of the present application are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship.

[0058] Referring to "embodiment" in the present application means that a specific feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0059] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "joined", and "attached" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0060] The term "and / or" in the present application is merely an association relationship describing associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present application generally represents an "or" relationship between the associated objects before and after.

[0061] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thicknesses, lengths, widths, etc. of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width, etc. of the integrated device, are only illustrative descriptions and should not constitute any limitation to the present application.

[0062] The "plurality" mentioned in the present application refers to two or more (including two).

[0063] Currently, from the perspective of the development of the market situation, the application of battery devices is becoming more and more extensive. Battery devices are not only applied to energy storage power systems such as hydraulic, thermal, wind, and solar power stations, but also widely applied to electric transportation means such as electric bicycles, electric motorcycles, and electric vehicles, as well as multiple fields such as aerospace. With the continuous expansion of the application fields of battery devices, the market demand is also continuously increasing.

[0064] A battery device generally refers to a single physical module including a plurality of battery cells to provide a higher voltage and capacity. A battery cell can be the smallest unit that makes up a battery device.

[0065] A battery cell includes an electrode assembly, and the electrode assembly is the component in the battery cell where an electrochemical reaction occurs. The electrode assembly includes a positive electrode tab and a negative electrode tab, and the positive electrode tab and the negative electrode tab can conduct current during the cycle of the battery cell. When current flows through the positive electrode tab and the negative electrode tab, heat is generated; due to the material or other reasons, the temperature of the positive electrode tab may be higher than that of the negative electrode tab, which will affect the temperature uniformity of the electrode assembly, cause the local temperature of the electrode assembly to be too high, and affect the cycle performance and cycle life of the battery cell.

[0066] In view of this, the present application provides a technical solution, which differentially designs the current-carrying cross-sectional area of the positive electrode tab and the current-carrying cross-sectional area of the negative electrode tab, thereby reducing the temperature difference between the positive electrode tab and the negative electrode tab and improving the cycle performance and cycle life of the battery cell.

[0067] The battery device described in the embodiments of the present application is applicable to the electrical device using the battery device. The electrical device can be a device using the battery device as a power source or various energy storage systems using the battery device as an energy storage element. The electrical device can be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric aircraft toy, and the like, and the spacecraft can include an airplane, a rocket, a space shuttle, a spaceship, and the like.

[0068] For the convenience of description, the following embodiments take the electrical device as a vehicle as an example for description.

[0069] Figure 1 It is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0070] As Figure 1 shown, a battery device 2 is disposed inside the vehicle 1, and the battery device 2 can be disposed at the bottom, head, or tail of the vehicle 1. The battery device 2 can be used for the power supply of the vehicle 1. For example, the battery device 2 can be used as the operating power source of the vehicle 1.

[0071] The vehicle 1 may further include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4. For example, it is used for the working power requirements during the start, navigation, and driving of the vehicle 1.

[0072] In some embodiments of the present application, the battery device 2 can not only be used as the operating power source of the vehicle 1, but also be used as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0073] Figure 2 It is a schematic diagram of a battery device provided in some embodiments of the present application.

[0074] In some embodiments, the battery device 2 may include one or more battery cell components for providing voltage and capacity.

[0075] The battery cell component may include a plurality of battery cells 6, and the plurality of battery cells 6 are connected in series, parallel, or in a series-parallel combination through a busbar component. Series-parallel combination means that there are both series and parallel connections among the plurality of battery cells 6.

[0076] The battery cell 6 can be a secondary battery cell, which refers to a battery cell that can be activated by charging after discharging so that the active material can be reused.

[0077] As an example, the battery cell 6 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium-metal battery cell, a sodium-metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0078] As an example, the battery cell 6 can be a cylindrical battery cell, a prismatic battery cell, a pouch 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 multi-prismatic battery cell, and the multi-prismatic battery cell is, for example, a hexagonal prism battery cell, etc.

[0079] In some embodiments, the battery cell assembly is usually formed by arranging a plurality of battery cells 6; as an example, the battery cell assembly can be a battery module, and the battery module is formed by arranging and fixing a plurality of battery cells 6 to form an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells 6 with a cable tie.

[0080] In some embodiments, the battery device 2 can be a battery pack, and the battery pack includes a box body 5 and one or more battery cell assemblies, and the battery cell assemblies are accommodated in the box body 5. As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be accommodated in the box body by fixing the battery module in the box body. As an example, the battery cell assembly can also be accommodated in the box body by directly fixing a plurality of battery cells 6 to the box body.

[0081] In some embodiments, the box body 5 is used to accommodate the battery cell 6, and the box body 5 can have various structures.

[0082] In some embodiments, the box body 5 can include a first box body part 5a and a second box body part 5b. The first box body part 5a and the second box body part 5b are covered with each other, and the first box body part 5a and the second box body part 5b jointly define an accommodation space for accommodating the battery cell 6. The second box body part 5b can be a hollow structure with one end open, and the first box body part 5a is a plate-like structure. The first box body part 5a covers the open side of the second box body part 5b to form the box body 5 with an accommodation space; both the first box body part 5a and the second box body part 5b can also be hollow structures with one side open, and the open side of the first box body part 5a covers the open side of the second box body part 5b to form the box body 5 with an accommodation space. Of course, the first box body part 5a and the second box body part 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0083] In some embodiments, the box body 5 may be part of the chassis structure of a vehicle. For example, part of the box body 5 may form at least part of the floor of the vehicle, or part of the box body 5 may form at least part of the cross beams and longitudinal beams of the vehicle.

[0084] In some embodiments, the battery device 2 may be an energy storage device. The energy storage device includes an energy storage container, an energy storage electrical cabinet, etc.

[0085] Figure 3 Explosion schematic diagram of a battery cell provided by some embodiments of the present application; Figure 4 Schematic diagram of the electrode assembly of a battery cell provided by some embodiments of the present application; Figure 5 Schematic diagram of the positive electrode plate of a battery cell provided by some embodiments of the present application in a flattened state, Figure 6 is Figure 5 Cross-sectional schematic diagram taken along the A-A direction; Figure 7 Schematic diagram of the negative electrode plate of a battery cell provided by some embodiments of the present application in a flattened state, Figure 8 is Figure 7 Cross-sectional schematic diagram taken along the B-B direction.

[0086] Referring to Figure 3 and Figure 4 , the battery cell includes a housing 20 and an electrode assembly 10, and at least part of the electrode assembly 10 is accommodated in the housing 20.

[0087] The housing 20 is a hollow structure, and an accommodation space for accommodating the electrode assembly 10 and the electrolyte is formed inside it. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cuboid structure, a cuboid housing can be selected.

[0088] In some embodiments, the housing 20 includes a shell 21 and an end cap 22, the shell 21 has an opening, and the end cap 22 is connected to the shell 21 and covers the opening;

[0089] The shell 21 is a component for cooperating with the end cap 22 to form the internal cavity of the battery cell 6, and the formed internal cavity can be used to accommodate the electrode assembly 10, the electrolyte solution, and other components.

[0090] The shell 21 and the end cap 22 may be independent components. Exemplarily, an opening may be provided on the shell 21, and the end cap 22 is covered at the opening to form the internal cavity of the battery cell 6.

[0091] The housing 21 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 21 can be determined according to the specific shape and size of the electrode assembly 10. The material of the housing 21 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of the present application do not make special restrictions on this.

[0092] The shape of the end cap 22 can be adapted to the shape of the housing 21 to cooperate with the housing 21. The material of the end cap 22 can be the same as or different from that of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). In this way, the end cap 22 is not easily deformed when being squeezed or collided, so that the battery cell 6 can have higher structural strength and the reliability can also be improved.

[0093] The end cap 22 is connected to the housing 21 by welding, bonding, clamping or other means.

[0094] One end of the housing 21 can be open, or both ends can be open. In some examples, the housing 21 can be a structure with one side open, and the end cap 22 is provided as one and covers the housing 21. In other examples, the housing 21 can also be a structure with both sides open, and the end caps 22 are provided as two, and the two end caps 22 respectively cover the two openings of the housing 21.

[0095] The electrode assembly 10 is a component in the battery cell 6 where an electrochemical reaction occurs. The housing 21 can contain one or more electrode assemblies 10.

[0096] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 11 and a negative electrode sheet 12. During the charge and discharge process of the battery cell 6, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode sheet 11 and the negative electrode sheet 12.

[0097] In some embodiments, the electrode assembly 10 further includes a separator 13. The separator 13 is disposed between the positive electrode sheet 11 and the negative electrode sheet 12, which can play a role in preventing short circuit between the positive and negative electrodes, and at the same time allows active ions to pass through.

[0098] In some embodiments, the electrode assembly 10 is a wound structure. The positive electrode sheet 11 and the negative electrode sheet 12 are wound into a wound structure.

[0099] In some embodiments, the electrode assembly 10 is a stacked structure.

[0100] As an example, a plurality of positive electrode sheets 11 and negative electrode sheets 12 can be respectively provided, and the plurality of positive electrode sheets 11 and the plurality of negative electrode sheets 12 are alternately stacked.

[0101] As an example, multiple positive electrode sheets 11 may be provided. The negative electrode sheet 12 is folded to form multiple stacked folding segments, and a positive electrode sheet 11 is clamped between adjacent folding segments.

[0102] As an example, both the positive electrode sheet 11 and the negative electrode sheet 12 are folded to form multiple stacked folding segments.

[0103] As an example, multiple separators 13 may be provided and are respectively disposed between any adjacent positive electrode sheets 11 or negative electrode sheets 12.

[0104] As an example, the separator 13 may be continuously provided and is disposed between any adjacent positive electrode sheets 11 or negative electrode sheets 12 by folding or winding.

[0105] In some embodiments, the positive electrode sheet 11 includes a positive electrode main body portion 111 and a positive electrode tab 112. The positive electrode main body portion 111 is provided with a positive electrode active material layer 113, and the positive electrode tab 112 extends from the edge of the positive electrode main body portion 111.

[0106] There may be one or multiple positive electrode tabs 112. As an example, in the electrode assembly 10 having a winding structure, there may be multiple positive electrode tabs 112, and the multiple positive electrode tabs 112 may be spaced along the winding direction of the positive electrode sheet 11. As an example, in the electrode assembly 10 having a stacked structure, the positive electrode tab 112 may be one or multiple.

[0107] As an example, the positive electrode sheet 11 may include a positive electrode current collector 114 and a positive electrode active material layer 113 provided on at least one surface of the positive electrode current collector 114. The positive electrode current collector 114 has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer 113 is provided on either one or both of the two opposite surfaces of the positive electrode current collector 114.

[0108] The positive electrode current collector 114 may include a positive electrode coating area 115 and a positive electrode tab 112. The surface of the positive electrode coating area 115 is coated with the positive electrode active material layer 113, and the positive electrode tab 112 extends and protrudes from the edge of the positive electrode coating area 115. The positive electrode main body portion 111 includes the positive electrode coating area 115 and the positive electrode active material layer 113. At least a part of the positive electrode tab 112 is not coated with the positive electrode active material layer 113. For example, the root of the positive electrode tab 112 close to the positive electrode coating area 115 may be coated with the positive electrode active material layer 113.

[0109] In some embodiments, the positive electrode current collector 114 may be made of a metal foil, such as aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc.

[0110] As an example, the positive electrode active material layer 113 includes a positive electrode active material, which may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of the lithium-containing phosphate may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and at least one of a composite material of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be abbreviated as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 )、lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2) and their modified compounds, etc.

[0111] In some embodiments, the negative electrode sheet 12 includes a negative electrode main body portion 121 and a negative electrode tab 122. The negative electrode main body portion 121 is provided with a negative electrode active material layer 123, and the negative electrode tab 122 extends from the edge of the negative electrode main body portion 121.

[0112] The negative electrode tab 122 can be one or multiple. As an example, in the electrode assembly 10 with a winding structure, the negative electrode tab 122 can be multiple, and the multiple negative electrode tabs 122 can be arranged at intervals along the winding direction of the negative electrode sheet 12. As an example, in the electrode assembly 10 with a stacked structure, the negative electrode tab 122 can be one or multiple.

[0113] As an example, the negative electrode sheet 12 can include a negative electrode current collector 124 and a negative electrode active material layer 123 provided on at least one surface of the negative electrode current collector 124. The negative electrode current collector 124 has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer 123 is provided on any one or both of the two opposite surfaces of the negative electrode current collector 124.

[0114] The negative electrode current collector 124 can include a negative electrode coating area 125 and a negative electrode tab 122. The surface of the negative electrode coating area 125 is coated with the negative electrode active material layer 123, and the negative electrode tab 122 extends and protrudes from the edge of the negative electrode coating area 125. The negative electrode main body 121 includes the negative electrode coating area 125 and the negative electrode active material layer 123. At least part of the negative electrode tab 122 is not coated with the negative electrode active material layer 123. For example, the root of the negative electrode tab 122 close to the negative electrode coating area 125 can be coated with the negative electrode active material layer 123.

[0115] In some embodiments, the positive electrode main body 111, the negative electrode main body 121, and the separator 13 constitute the electrode main body 10a of the electrode assembly 10. The positive electrode tab 112 and the negative electrode tab 122 are led out from the electrode main body 10a. The positive electrode tab 112 and the negative electrode tab 122 can be led out from the same end of the electrode main body 10a, or can be led out from the two ends of the electrode main body 10a respectively.

[0116] In some embodiments, the negative electrode current collector 124 can adopt a metal foil. For example, it can adopt aluminum or stainless steel with silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc.

[0117] In some embodiments, the negative electrode active material layer 123 includes a negative electrode active material. For example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy.

[0118] In some embodiments, the material of the positive electrode current collector 114 can be aluminum, and the material of the negative electrode current collector 124 can be copper.

[0119] The separator 13 can be a separator film, and the material of the separator film can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film. When the separator film is a multi-layer composite film, the materials of each layer can be the same or different. The separator 13 can be a component independently disposed between the positive electrode sheet 11 and the negative electrode sheet 12, or can be attached to the surface of the positive electrode sheet 11 or the surface of the negative electrode sheet 12.

[0120] In some embodiments, the battery cell 6 includes a positive electrode lead-out portion 30 and a negative electrode lead-out portion 40. The positive electrode lead-out portion 30 is connected to the positive electrode tab 112, and the negative electrode lead-out portion 40 is connected to the negative electrode tab 122.

[0121] The positive electrode lead-out portion 30 and the negative electrode lead-out portion 40 are used for electrically connecting to an external circuit to achieve charging or discharging of the battery cell 6.

[0122] In some embodiments, the positive electrode lead-out portion 30 includes a positive electrode terminal 31. At least a part of the positive electrode terminal 31 is exposed to the outside of the battery cell 6 to facilitate connection to a bus bar component.

[0123] As an example, the positive electrode terminal 31 can be an independently formed component, which is installed on the housing 20. Alternatively, the positive electrode terminal 31 can also be a part of the housing 20.

[0124] In some examples, the positive electrode terminal 31 is directly connected to the positive electrode tab 112; in other examples, the positive electrode lead-out portion 30 further includes other conductive structures connecting the positive electrode terminal 31 and the positive electrode tab 112, such as a positive electrode adapter piece 32.

[0125] In some embodiments, the positive electrode terminal 31 is connected to the end cap 22 by welding, riveting, clamping or other means.

[0126] In some embodiments, the negative electrode lead-out portion 40 includes a negative electrode terminal 41. At least a part of the negative electrode terminal 41 is exposed to the outside of the battery cell 6 to facilitate connection to a bus bar component.

[0127] As an example, the negative electrode terminal 41 can be an independently formed component, which is installed on the housing 20. Alternatively, the negative electrode terminal 41 can also be a part of the housing 20.

[0128] In some examples, the negative electrode terminal 41 is directly connected to the negative electrode tab 122; in other examples, the negative electrode lead-out portion 40 further includes other conductive structures connecting the negative electrode terminal 41 and the negative electrode tab 122, such as a negative electrode adapter piece 42.

[0129] In some embodiments, the negative electrode terminal 41 is connected to the end cap 22 by welding, riveting, clamping or other means.

[0130] Figure 9 A cross-sectional schematic view of a battery cell provided in some embodiments of the present application; Figure 10 An enlarged schematic view at box C; Figure 11 is Figure 9 An enlarged schematic view at box D; Figure 12 Another cross-sectional schematic view of a battery cell provided in some embodiments of the present application; Figure 13 A schematic view of a battery cell provided in some embodiments of the present application during the assembly process; Figure 14 is Figure 5 An enlarged schematic view at the circular frame; Figure 15 is Figure 7 An enlarged schematic view at the circular frame.

[0131] Please refer to Figures 3 to 15 , the battery cell 6 of the embodiments of the present application includes an electrode assembly 10, a housing 20, a positive electrode lead-out portion 30, and a negative electrode lead-out portion 40. The positive electrode lead-out portion 30 and the negative electrode lead-out portion 40 are provided on the housing 20. The electrode assembly 10 is accommodated in the housing 20. The electrode assembly 10 includes a positive electrode plate 11 and a negative electrode plate 12. The positive electrode plate 11 includes a positive electrode main body portion 111 and a positive electrode tab 112. The positive electrode main body portion 111 is provided with a positive electrode active material layer 113, and the positive electrode tab 112 extends from the edge of the positive electrode main body portion 111. The negative electrode plate 12 includes a negative electrode main body portion 121 and a negative electrode tab 122. The negative electrode main body portion 121 is provided with a negative electrode active material layer 123, and the negative electrode tab 122 extends from the edge of the negative electrode main body portion 121. A plurality of positive electrode tabs 112 of the electrode assembly 10 are welded to the positive electrode lead-out portion 30 to form a first welding mark P1, and a plurality of negative electrode tabs 122 of the electrode assembly 10 are welded to the negative electrode lead-out portion 40 to form a second welding mark P2.

[0132] The conductivity of the negative electrode tab 122 is greater than the conductivity of the positive electrode tab 112.

[0133] The positive electrode tab 112 includes a positive electrode connection portion 1121. One end of the positive electrode connection portion 1121 is connected to the positive electrode main body portion 111, and the other end is connected to the first welding mark P1. The negative electrode tab 122 includes a negative electrode connection portion 1221. One end of the negative electrode connection portion 1221 is connected to the negative electrode main body portion 121, and the other end is connected to the second welding mark P2. The sum of the minimum current-carrying cross-sectional areas of the positive electrode connection portions 1121 of the plurality of positive electrode tabs 112 is S1; the sum of the minimum current-carrying cross-sectional areas of the negative electrode connection portions 1221 of the plurality of negative electrode tabs 122 is S2. S1 is greater than S2.

[0134] The electrode assembly 10 can be one or more. As an example, there are two electrode assemblies 10. A plurality of positive electrode tabs 112 of one electrode assembly 10 are welded to the positive electrode lead-out portion 30 to form a first welding mark P1, and a plurality of positive electrode tabs 112 of the other electrode assembly 10 are welded to the positive electrode lead-out portion 30 to form another first welding mark P1; a plurality of negative electrode tabs 122 of one electrode assembly 10 are welded to the negative electrode lead-out portion 40 to form a second welding mark P2, and a plurality of negative electrode tabs 122 of the other electrode assembly 10 are welded to the negative electrode lead-out portion 40 to form another second welding mark P2.

[0135] As an example, when there are multiple electrode assemblies 10, the size relationship between S1 and S2 is for the same electrode assembly 10.

[0136] As an example, in the width direction X1 of the positive electrode tab 112, the size of the positive electrode connection portion 1121 can be greater than or equal to the size of the first welding mark P1. In the width direction X1 of the positive electrode tab 112, the positive electrode connection portion 1121 can extend to both edges of the positive electrode tab 112.

[0137] As an example, in the width direction X2 of the negative electrode tab 122, the size of the negative electrode connection portion 1221 can be greater than or equal to the size of the second welding mark P2. In the width direction X2 of the negative electrode tab 122, the negative electrode connection portion 1221 can extend to both edges of the negative electrode tab 122.

[0138] As an example, the current-carrying cross-section of the positive electrode connection portion 1121 can be a cross-section perpendicular to the extending direction of the positive electrode tab 112. After flattening the positive electrode tab 112, the current-carrying cross-section of the positive electrode connection portion 1121 is parallel to the thickness direction and the width direction of the positive electrode tab 112. The minimum current-carrying cross-sectional area of the positive electrode connection portion 1121 is the area of the smallest current-carrying cross-section of the positive electrode connection portion 1121.

[0139] As an example, the current-carrying cross-section of the negative electrode connection portion 1221 can be a cross-section perpendicular to the extending direction of the negative electrode tab 122. After flattening the negative electrode tab 122, the current-carrying cross-section of the negative electrode connection portion 1221 is parallel to the thickness direction and the width direction of the negative electrode tab 122. The minimum current-carrying cross-sectional area of the negative electrode connection portion 1221 is the area of the smallest current-carrying cross-section of the negative electrode connection portion 1221.

[0140] In the electrode assembly 10, the minimum current-carrying cross-sectional areas of the positive electrode connection portions 1121 of the plurality of positive electrode tabs 112 can be the same or different. As an example, the number of positive electrode tabs 112 of the electrode assembly 10 is m, and the minimum current-carrying cross-sectional area of the positive electrode connection portion 1121 is S 11 , S1 = m × S 11 .

[0141] In the electrode assembly 10, the minimum current-carrying cross-sectional areas of the negative electrode connection portions 1221 of the plurality of negative electrode tabs 122 may be the same or different. As an example, the number of negative electrode tabs 122 of the electrode assembly 10 is n, and the minimum current-carrying cross-sectional area of the negative electrode connection portion 1221 is S 21 , S2 = n × S 21 . m may be greater than, equal to, or less than n.

[0142] During the cycling of the battery cell 6, the positive electrode connection portion 1121 and the negative electrode connection portion 1221 function to collect and transmit current, and the positive electrode connection portion 1121 and the negative electrode connection portion 1221 generate heat when current passes through; the positive electrode connection portion 1121 and the negative electrode connection portion 1221 are directly connected to the positive electrode main body portion 111 and the negative electrode main body portion 121 respectively, and the heat generation of the positive electrode connection portion 1121 and the heat generation of the negative electrode connection portion 1221 will affect the cycling performance of the battery cell 6.

[0143] In the embodiments of the present application, S1 is set to be greater than S2 to reduce the difference in current-carrying capacity between the plurality of positive electrode connection portions 1121 and the plurality of negative electrode connection portions 1221 caused by different conductivities, reduce the temperature difference between the positive electrode connection portion 1121 and the negative electrode connection portion 1221, and further reduce the temperature difference between the positive electrode main body portion 111 and the negative electrode main body portion 121, thereby improving the cycling performance and cycling life of the battery cell 6.

[0144] In some embodiments, the positive terminal 31 and the negative terminal 41 are both disposed on the end cap 22. As an example, the end cap 22, the positive terminal 31, and the negative terminal 41 may be pre-assembled together and then assembled with the electrode assembly 10 and the housing 21.

[0145] Exemplarily, the battery cell 6 includes an end cap assembly, and the end cap assembly includes an end cap 22, a positive terminal 31, and a negative terminal 41. Optionally, both the positive terminal 31 and the negative terminal 41 are insulated from the end cap 22. Optionally, the positive terminal 31 is riveted to the end cap 22, and the negative terminal 41 is riveted to the end cap 22.

[0146] In some embodiments, the positive electrode tab 112 extends from one end of the positive electrode main body portion 111 along the first direction Z.

[0147] In some embodiments, the width direction X1 of the positive electrode tab 112 is parallel to the second direction X, and the second direction X is perpendicular to the first direction Z.

[0148] Optionally, the first direction Z, the second direction X, and the third direction Y are perpendicular to each other in pairs, and the third direction Y may be parallel to the thickness direction of the battery cell 6.

[0149] In some embodiments, the electrode body 10a and the first welding mark P1 are arranged at intervals in the first direction Z, and the positive electrode connecting portion 1121 is bent. By bending the positive electrode connecting portion 1121, the space occupied by the positive electrode tab 112 in the first direction Z can be saved, and the space utilization rate can be improved.

[0150] In some embodiments, in the width direction X1 of the positive electrode tab 112, both ends of the positive electrode connecting portion 1121 extend beyond the first welding mark P1.

[0151] Exemplarily, the positive electrode tab 112 further includes two first positive electrode portions 1122. In the width direction X1 of the positive electrode tab 112, the two first positive electrode portions 1122 are respectively located on both sides of the first welding mark P1 and connected to the first welding mark P1. One end of the positive electrode connecting portion 1121 far from the positive electrode main body portion 111 is connected to the two first positive electrode portions 1122 and the first welding mark P1.

[0152] Exemplarily, the positive electrode tab 112 further includes a second positive electrode portion 1123. The second positive electrode portion 1123 is connected to the two first positive electrode portions 1122 and the first welding mark P1. In the extending direction of the positive electrode tab 112, the first positive electrode portion 1122 connects the positive electrode connecting portion 1121 and the second positive electrode portion 1123.

[0153] As an example, Figure 14 shows the state of the positive electrode tab before welding. In Figure 14 it, the area surrounded by the rectangular dotted line box can be the positive electrode welding area 1124 of the positive electrode tab 112. When multiple positive electrode tabs 112 are welded to the positive electrode lead-out portion 30, the positive electrode welding areas 1124 of the multiple positive electrode tabs 112 are melted and form the first welding mark P1 after solidification.

[0154] The positive electrode welding area 1124 and the two first positive electrode portions 1122 form the middle area of the positive electrode tab 112; in the extending direction of the positive electrode tab 112, the positive electrode connecting portion 1121, the middle area of the positive electrode tab 112, and the second positive electrode portion 1123 are arranged in sequence.

[0155] In some embodiments, in the width direction X1 of the positive electrode tab 112, the minimum width of the positive electrode connecting portion 1121 is W1. The thickness of the positive electrode tab 112 is T1. S 11 = W1 × T1.

[0156] In some embodiments, the negative electrode tab 122 extends from one end of the negative electrode main body portion 121 in the first direction Z.

[0157] In some embodiments, the width direction X2 of the negative electrode tab 122 is parallel to the width direction X1 of the positive electrode tab 112.

[0158] In some embodiments, the electrode body 10a and the second welding mark P2 are spaced apart along the first direction Z, and the negative electrode connecting portion 1221 is bent. By bending the negative electrode connecting portion 1221, the space occupied by the negative electrode tab 122 in the first direction Z can be saved, and the space utilization rate can be improved.

[0159] In some embodiments, in the width direction X2 of the negative electrode tab 122, both ends of the negative electrode connecting portion 1221 extend beyond the second welding mark P2.

[0160] Exemplarily, the negative electrode tab 122 further includes two first negative electrode portions 1222. In the width direction X2 of the negative electrode tab 122, the two first negative electrode portions 1222 are respectively located on both sides of the second welding mark P2 and connected to the second welding mark P2. One end of the negative electrode connecting portion 1221 far from the negative electrode main body portion 121 is connected to the two first negative electrode portions 1222 and the second welding mark P2.

[0161] Exemplarily, the negative electrode tab 122 further includes a second negative electrode portion 1223. The second negative electrode portion 1223 is connected to the two first negative electrode portions 1222 and the second welding mark P2. In the extending direction of the negative electrode tab 122, the first negative electrode portion 1222 connects the negative electrode connecting portion 1221 and the second negative electrode portion 1223.

[0162] As an example, Figure 15 shows the state of the negative electrode tab 122 before welding. In Figure 15 , the area enclosed by the rectangular dashed line box can be the negative electrode welding area 1224 of the negative electrode tab 122. When multiple negative electrode tabs 122 are welded to the negative electrode lead-out portion 40, the negative electrode welding areas 1224 of the multiple negative electrode tabs 122 are melted and form the second welding mark P2 after solidification.

[0163] The negative electrode welding area 1224 and the two first negative electrode portions 1222 form the middle area of the negative electrode tab 122; in the extending direction of the negative electrode tab 122, the negative electrode connecting portion 1221, the middle area of the negative electrode tab 122, and the second negative electrode portion 1223 are arranged in sequence.

[0164] In some embodiments, in the width direction X2 of the negative electrode tab 122, the minimum width of the negative electrode connecting portion 1221 is W2. The thickness of the negative electrode tab 122 is T2. S 21 = W2 × T2.

[0165] In some embodiments, the conductivity of the positive electrode tab 112 is σ c , and the conductivity of the negative electrode tab 122 is σ a . S1 / S2 ≥ σ a / σ c .

[0166] In the embodiments of the present application, S1 and S2 are set according to the conductivity of the positive electrode tab 112 and the conductivity of the negative electrode tab 122, which can further reduce the difference in the overcurrent capacity between the plurality of positive electrode connection portions 1121 and the plurality of negative electrode connection portions 1221, reduce the temperature difference between the positive electrode connection portion 1121 and the negative electrode connection portion 1221, and further reduce the temperature difference between the positive electrode main body portion 111 and the negative electrode main body portion 121, thereby improving the cycling performance and cycling life of the battery cell 6.

[0167] In some embodiments, S1 / S2 is 1.1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, 2.2, 2.5, 2.8 or 3.

[0168] In some embodiments, σ c is 2×10 7 S / m - 5×10 7 S / m. Exemplarily, σ c is 3.77×10 7 S / m.

[0169] In some embodiments, σ a is 4×10 7 S / m - 7×10 7 S / m. Exemplarily, σ c is 5.85×10 7 S / m.

[0170] In some embodiments, the total volume V1 of the plurality of positive electrode connection portions 1121 is greater than or equal to the total volume V2 of the plurality of negative electrode connection portions 1221. By increasing the total volume of the plurality of positive electrode connection portions 1121, the overcurrent capacity of the plurality of positive electrode connection portions 1121 can be improved, and the difference in the overcurrent capacity between the plurality of positive electrode connection portions 1121 and the plurality of negative electrode connection portions 1221 can be reduced.

[0171] In some embodiments, the positive electrode connection portion 1121 has two first surfaces 1121a opposite to each other along its own thickness direction, and the area of the first surface 1121a is S c ; the negative electrode connection portion 1221 has two second surfaces 1221a opposite to each other along its own thickness direction, and the area of the second surface 1221a is S a . The thermal conductivity of the negative electrode tab 122 is greater than the thermal conductivity of the positive electrode tab 112, and S c is greater than S a .

[0172] As an example, the positive electrode connection portion 1121 is bent; correspondingly, the first surface 1121a is also bent into a curved surface. Optionally, S c can be measured and calculated when the positive electrode connection portion 1121 is in a flattened state.

[0173] As an example, the area S of the first surface 1121a of the positive electrode connection portions 1121 of multiple positive electrode tabs 112 c can be different. Specifically, multiple positive electrode tabs 112 need to be gathered together first and then welded to the positive electrode lead-out portion 30; after welding, the extended lengths of the positive electrode connection portions 1121 of multiple positive electrode tabs 112 may be different, resulting in the area S of the first surface 1121a of multiple positive electrode connection portions 1121 c being different.

[0174] As an example, the negative electrode connection portion 1221 is bent; correspondingly, the second surface 1221a is also bent into a curved surface. Optionally, S a can be measured and calculated when the negative electrode connection portion 1221 is in a flattened state.

[0175] As an example, the area S of the first surface 1121a of the negative electrode connection portions 1221 of multiple negative electrode tabs 122 a can be different. Specifically, multiple negative electrode tabs 122 need to be gathered together first and then welded to the negative electrode lead-out portion 40; after welding, the extended lengths of the negative electrode connection portions 1221 of multiple negative electrode tabs 122 may be different, resulting in the area S of the first surface 1121a of multiple negative electrode connection portions 1221 a being different.

[0176] Compared with the negative electrode tab 122, the positive electrode tab 112 has a poor heat conduction ability; in the embodiments of the present application, S c is greater than S a , so as to increase the heat dissipation area of the positive electrode tab 112, reduce the temperature rise of the positive electrode tab 112 during overcurrent, reduce the temperature difference between the positive electrode connection portion 1121 and the negative electrode connection portion 1221, improve the temperature consistency, and enhance the cycle performance of the battery cell 6.

[0177] In some embodiments, the volume V of the positive electrode connection portion 1121 c = S c × T1.

[0178] In some embodiments, the volume V of the negative electrode connection portion 1221 a = S a × T2.

[0179] In some embodiments, V c / V a ≥ σ a / σ c .

[0180] In some embodiments, the minimum width W1 of the positive electrode connection portion 1121 is greater than the minimum width W2 of the negative electrode connection portion 1221.

[0181] Compared with the negative electrode connection part 1221, the positive electrode connection part 1121 can have a larger width, so as to increase the current-carrying cross-sectional area and heat dissipation area of the positive electrode connection part 1121, reduce the difference in current-carrying capacity between the positive electrode connection part 1121 and the negative electrode connection part 1221, reduce the temperature difference between the positive electrode connection part 1121 and the negative electrode connection part 1221, and improve the cycle performance of the battery cell 6.

[0182] In some embodiments, the thickness T1 of the positive electrode tab 112 is greater than the thickness T2 of the negative electrode tab 122.

[0183] Compared with the negative electrode tab 122, the positive electrode tab 112 can have a larger thickness, so as to increase the current-carrying cross-sectional area and heat dissipation area of the positive electrode connection part 1121, reduce the difference in current-carrying capacity between the positive electrode connection part 1121 and the negative electrode connection part 1221, reduce the temperature difference between the positive electrode connection part 1121 and the negative electrode connection part 1221, and improve the cycle performance of the battery cell 6.

[0184] In some embodiments, the thickness T1 of the positive electrode tab 112 is 10 μm to 15 μm, and can be optionally 12 μm to 15 μm. Exemplarily, T1 is 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, 15 μm or a range composed of any two of the above values.

[0185] In some embodiments, the thickness T2 of the negative electrode tab 122 is 5 μm to 12 μm, and can be optionally 6 μm to 10 μm. Exemplarily, T1 is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm or a range composed of any two of the above values.

[0186] In some embodiments, the number m of the positive electrode tabs 112 is greater than the number n of the negative electrode tabs 122.

[0187] The m positive electrode tabs 112 are stacked, and the n negative electrode tabs 122 are stacked.

[0188] The embodiments of the present application can increase the positive electrode connection part 1121, reduce the difference in current-carrying capacity between the multiple positive electrode connection parts 1121 and the multiple negative electrode connection parts 1221, reduce the temperature difference between the positive electrode connection part 1121 and the negative electrode connection part 1221, and further reduce the temperature difference between the positive electrode main body part 111 and the negative electrode main body part 121, and improve the cycle performance and cycle life of the battery cell 6.

[0189] In some embodiments, m / n ≥ σ a / σ c .

[0190] In the embodiments of the present application, m and n are set according to the conductivity of the positive electrode tab 112 and the conductivity of the negative electrode tab 122, which can further reduce the difference in the over-current capacity between the plurality of positive electrode connection portions 1121 and the plurality of negative electrode connection portions 1221, reduce the temperature difference between the positive electrode connection portion 1121 and the negative electrode connection portion 1221, and further reduce the temperature difference between the positive electrode main body portion 111 and the negative electrode main body portion 121, thereby improving the cycle performance and cycle life of the battery cell 6.

[0191] In some embodiments, the electrode assembly 10 has a wound structure. The number of layers of the positive electrode main body portion 111 stacked along the third direction Y is M, and the number of layers of the negative electrode main body portion 121 stacked along the third direction Y is N.

[0192] In some embodiments, 1 / 2 ≤ m / M ≤ 1, optionally, 5 / 8 ≤ m / M ≤ 3 / 4. The positive electrode tab 112 has a relatively large number, thereby improving the over-current capacity, reducing the temperature rise of the positive electrode tab 112, and enhancing the fast charging capacity of the battery cell 6. When the over-current capacity meets the requirements, making m / M ≤ 3 / 4 can reduce the increase in the number of positive electrode tabs 112 and reduce the impact on the energy density.

[0193] In some embodiments, 1 / 2 ≤ n / N ≤ 1, optionally, 5 / 8 ≤ n / N ≤ 3 / 4. The negative electrode tab 122 has a relatively large number, thereby improving the over-current capacity, reducing the temperature rise of the negative electrode tab 122, and enhancing the fast charging capacity of the battery cell 6. When the over-current capacity meets the requirements, making n / N ≤ 3 / 4 can reduce the increase in the number of negative electrode tabs 122 and reduce the impact on the energy density.

[0194] In some embodiments, the area S of the first welding mark P1 c1 is greater than the area S of the second welding mark P2 a1 .

[0195] As an example, the first welding mark P1 has a first welding surface facing the electrode main body 10a, and the first welding surface is formed on the positive electrode tab 112. The area of the first welding surface can be used as the area of the first welding mark P1.

[0196] As an example, the second welding mark P2 has a second welding surface facing the electrode main body 10a, and the second welding surface is formed on the negative electrode tab 122. The area of the second welding surface can be used as the area of the second welding mark P2.

[0197] The embodiments of the present application can increase the over-current cross-sectional area of the first welding mark P1, reduce the difference in the over-current capacity between the first welding mark P1 and the second welding mark P2, increase the heat dissipation area of the first welding mark P1, reduce the temperature difference between the first welding mark P1 and the second welding mark P2, and improve the cycle performance and cycle life of the battery cell 6.

[0198] In some embodiments, the first welding mark P1 can be formed by ultrasonic welding, and the second welding mark P2 can be formed by ultrasonic welding.

[0199] In some embodiments, the first welding mark P1 includes one or more first strip-shaped welding marks that extend along the second direction X. The second welding mark P2 includes one or more second strip-shaped welding marks that extend along the second direction X.

[0200] Optionally, the dimension of the first strip-shaped welding mark along the second direction X is greater than the dimension of the second strip-shaped welding mark along the second direction X.

[0201] In some embodiments, the positive electrode lead-out portion 30 includes a positive electrode terminal 31 and a positive electrode adapter plate 32. The positive electrode adapter plate 32 is welded to a plurality of positive electrode tabs 112 to form the first welding mark P1. The positive electrode terminal 31 is disposed on the housing 20, and the positive electrode terminal 31 is welded to the positive electrode adapter plate 32 to form the third welding mark P3.

[0202] In some embodiments, the positive electrode adapter plate 32 and the plurality of positive electrode tabs 112 form the first welding mark P1 through ultrasonic welding. The positive electrode terminal 31 and the positive electrode adapter plate 32 form the third welding mark P3 through laser welding.

[0203] In some embodiments, the positive electrode terminal 31 is disposed on the end cap 22.

[0204] Exemplarily, the end cap 22 is provided with a positive electrode lead-out hole 221 that penetrates the end cap 22 along the thickness direction of the end cap 22. The positive electrode terminal 31 is disposed in the positive electrode lead-out hole 221.

[0205] In some embodiments, at least a part of the positive electrode terminal 31 is located outside the end cap 22 and covers the positive electrode lead-out hole 221.

[0206] In some embodiments, the whole of the positive electrode terminal 31 is located outside the end cap 22. Alternatively, at least a part of the positive electrode terminal 31 can be received in the positive electrode lead-out hole 221. For example, the positive electrode terminal 31 passes through the positive electrode lead-out hole 221 and is riveted to the end cap 22.

[0207] In some embodiments, the battery cell 6 includes a first insulating member 50 and a first fixing member 60. The first insulating member 50 at least partially surrounds the positive electrode terminal 31 and is fixed to the positive electrode terminal 31. The first fixing member 60 is connected to the end cap 22 and the first insulating member 50 to fix the positive electrode terminal 31 to the end cap 22 through the first insulating member 50.

[0208] Optionally, a part of the first fixing member 60 is embedded in the first insulating member 50.

[0209] In some embodiments, the negative electrode lead-out portion 40 includes a negative terminal 41 and a negative electrode adapter piece 42. The negative electrode adapter piece 42 is welded to a plurality of negative electrode tabs 122 to form a second weld mark P2. The negative terminal 41 is disposed on the housing 20, and the negative terminal 41 is welded to the negative electrode adapter piece 42 to form a fourth weld mark P4.

[0210] In some embodiments, the negative electrode adapter piece 42 and the plurality of negative electrode tabs 122 are ultrasonically welded to form the second weld mark P2. The negative terminal 41 and the negative electrode adapter piece 42 are laser welded to form the fourth weld mark P4.

[0211] In some embodiments, the negative terminal 41 is disposed on the end cap 22.

[0212] Exemplarily, the end cap 22 is provided with a negative electrode lead-out hole 222, and the negative electrode lead-out hole 222 penetrates the end cap 22 along the thickness direction of the end cap 22. The negative terminal 41 is disposed in the negative electrode lead-out hole 222.

[0213] In some embodiments, at least a part of the negative terminal 41 is located outside the end cap 22 and covers the negative electrode lead-out hole 222.

[0214] In some embodiments, the whole of the negative terminal 41 is located outside the end cap 22. Alternatively, at least a part of the negative terminal 41 can be received in the negative electrode lead-out hole 222. For example, the negative terminal 41 passes through the negative electrode lead-out hole 222 and is riveted to the end cap 22.

[0215] In some embodiments, the battery cell 6 includes a second insulating member 70 and a second fixing member 80. The second insulating member 70 at least partially surrounds the negative terminal 41 and is fixed to the negative terminal 41. The second fixing member 80 is connected to the end cap 22 and the second insulating member 70 to fix the negative terminal 41 to the end cap 22 through the second insulating member 70.

[0216] Optionally, a part of the second fixing member 80 is embedded in the second insulating member 70.

[0217] In some embodiments, the area of the third weld mark P3 is larger than the area of the fourth weld mark P4.

[0218] As an example, the third weld mark P3 has a third welding surface facing the electrode body 10a, and the third welding surface is formed on the positive electrode adapter piece 32. The area of the third welding surface can be used as the area of the third weld mark P3.

[0219] As an example, the fourth weld mark P4 has a fourth welding surface facing the electrode body 10a, and the fourth welding surface is formed on the negative electrode adapter piece 42. The area of the fourth welding surface can be used as the area of the fourth weld mark P4.

[0220] The embodiments of the present application can further improve the overcurrent capacity on the positive overcurrent chain of the battery cell 6, reduce the difference in overcurrent capacity between the positive and negative electrodes, improve overcurrent consistency, and improve the cycling performance of the battery cell 6.

[0221] In some embodiments, the volume of the positive electrode connecting tab 32 is greater than or equal to the volume of the negative electrode connecting tab 42 to enhance the overcurrent capacity of the positive electrode connecting tab 32 and increase the heat dissipation area of the positive electrode connecting tab 32.

[0222] In some embodiments, the minimum overcurrent distance between the first welding mark P1 and the third welding mark P3 is less than the minimum overcurrent distance between the second welding mark P2 and the fourth welding mark P4.

[0223] As an example, the positive electrode connecting tab 32 has two surfaces opposite to each other in its own thickness direction, one surface facing the positive electrode terminal 31 and the other surface facing the positive electrode tab 112. The minimum overcurrent distance between the first welding mark P1 and the third welding mark P3 may refer to: the minimum distance for the current to flow from the first welding mark P1 to the third welding mark P3 along the surface of the positive electrode connecting tab 32 facing the positive electrode tab 112.

[0224] As an example, the negative electrode connecting tab 42 has two surfaces opposite to each other in its own thickness direction, one surface facing the negative electrode terminal 41 and the other surface facing the negative electrode tab 122. The minimum overcurrent distance between the second welding mark P2 and the fourth welding mark P4 may refer to: the minimum distance for the current to flow from the second welding mark P2 to the fourth welding mark P4 along the surface of the negative electrode connecting tab 42 facing the negative electrode tab 122.

[0225] The embodiments of the present application can shorten the conduction path on the positive overcurrent chain of the battery cell 6, reduce the resistance, reduce the difference in overcurrent capacity between the positive and negative electrodes, and improve overcurrent consistency.

[0226] In some embodiments, the minimum overcurrent cross-sectional area of the positive electrode terminal 31 is greater than or equal to the minimum overcurrent cross-sectional area of the negative electrode terminal 41.

[0227] As an example, the minimum overcurrent cross-sectional area of the positive electrode terminal 31 may be: the area of the minimum cross-section of the positive electrode terminal 31 perpendicular to the axial direction of the positive electrode lead-out hole 221. The minimum overcurrent cross-sectional area of the negative electrode terminal 41 may be: the area of the minimum cross-section of the negative electrode terminal 41 perpendicular to the axial direction of the negative electrode lead-out hole 222.

[0228] By increasing the overcurrent area of the positive electrode terminal 31, the embodiments of the present application can reduce the difference in overcurrent capacity between the positive electrode terminal 31 and the negative electrode terminal 41 and reduce the temperature difference between the positive electrode terminal 31 and the negative electrode terminal 41 during overcurrent.

[0229] In some embodiments, the material of the positive electrode tab 112 is aluminum, and the material of the negative electrode tab 122 is copper. Both copper and aluminum have high thermal conductivity and electrical conductivity. By using an aluminum positive electrode tab 112 and a copper negative electrode tab 122, the overcurrent capacity can be improved, the temperature rise of the electrode assembly 10 can be reduced, and the cycle performance can be improved.

[0230] Compared with copper, aluminum has higher resistance and thermal resistance; in the embodiments of the present application, S1 is made greater than S2 to reduce the resistance difference and thermal resistance difference between the plurality of positive electrode connection portions 1121 and the plurality of negative electrode connection portions 1221, improve the consistency of the overcurrent capacity of the positive and negative electrodes and the consistency of the temperature rise, and improve the cycle performance.

[0231] In some embodiments, the material of the positive electrode adapter piece 32 is aluminum or aluminum alloy. The material of the negative electrode adapter piece 42 is copper or copper alloy.

[0232] In some embodiments, the material of the positive electrode terminal 31 is aluminum or aluminum alloy.

[0233] In some embodiments, the negative electrode terminal 41 may be a copper-aluminum composite structure. Exemplarily, the material of the part of the negative electrode terminal 41 connected to the negative electrode adapter piece 42 is copper.

[0234] In some embodiments, the volume of the positive electrode terminal 31 is greater than the volume of the negative electrode terminal 41.

[0235] In some embodiments, the average charging rate of the battery cell 6 is K, that is, the battery cell 6 can achieve KC fast charging. Optionally, K≥2. For example, K is 2, 3, 4, 5, or 6.

[0236] The battery cell 6 of the embodiments of the present application has fast charging ability.

[0237] In some embodiments, at room temperature, the charging time of the battery cell 6 from 10% SOC to 80% SOC is less than or equal to 16 minutes.

[0238] As an example, the room temperature may be an ambient temperature of 30°C.

[0239] SOC refers to the state of charge of the battery cell 6.

[0240] Exemplarily, 100% SOC and 0% SOC are defined as follows: The battery cell is charged at a constant current charging rate of 0.33C to the battery charging upper limit 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. Exemplarily, the battery charging upper limit voltage and the discharge cut-off voltage can be marked on the outer packaging film of the battery cell.

[0241] Exemplarily, the charging time of the battery cell from 10% SOC to 80% SOC is 16 min, 15 min, 14 min, 13 min, 12 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, 5.5 min, 5 min or a range composed of any two of the above values.

[0242] In the embodiments of the present application, the battery cell 6 has a fast charging capability, which can save the charging time and improve the user experience.

[0243] In some embodiments, the positive electrode tab 112 and the negative electrode tab 122 extend from the same end of the electrode body 10a along the first direction Z.

[0244] In the second direction X, the projection of the positive electrode tab 112 along the third direction Y and the projection of the negative electrode tab 122 along the third direction Y are arranged at intervals.

[0245] Figure 16 It is a schematic cross-sectional view of the positive electrode plate of the battery cell provided in some other embodiments of the present application.

[0246] Refer to Figure 16 , in some embodiments, the positive electrode plate 11 further includes a conductive layer 116 coated on the positive electrode connection portion 1121.

[0247] As an example, the conductive layer 116 may be coated only on the root region of the positive electrode connection portion 1121 close to the positive electrode main body portion 111.

[0248] By coating the conductive layer 116 in the embodiments of the present application, the overcurrent area can be increased and the heat generation of the positive electrode connection portion 1121 can be reduced.

[0249] Figure 17 It is a schematic diagram of the battery device provided in some other embodiments of the present application.

[0250] Refer to Figure 17 , in some embodiments, the battery device 2 includes a plurality of battery cells 6.

[0251] In some embodiments, the battery device 2 further includes a heat exchange member 7, and the heat exchange member 7 is used for heat exchange with the positive electrode lead-out portion 30.

[0252] As an example, the heat exchange member 7 includes a heat exchange tube.

[0253] The heat exchange member 7 can exchange heat with the positive electrode lead-out portion 30 in contact or indirectly exchange heat with the positive electrode lead-out portion 30 through other heat conduction structures.

[0254] The heat exchange member 7 can exchange heat with the negative electrode lead-out portion 40, or it can also not exchange heat with the negative electrode lead-out portion 40.

[0255] The heat exchange member 7 can exchange heat with the positive electrode tab 112 through the positive electrode lead-out portion 30, thereby reducing the temperature rise of the positive electrode tab 112 and improving the cycle performance of the battery cell 6.

[0256] According to some embodiments of the present application, the present application further provides an electrical device, including the battery device of any one of the above embodiments, and the battery device is used to provide electrical energy for the electrical device. The electrical device can be any of the aforementioned devices or systems applying the battery device.

[0257] Refer to Figures 3 to 15 , an embodiment of the present application provides a battery cell 6, which includes an electrode assembly 10, a housing 20, a positive electrode lead-out portion 30, and a negative electrode lead-out portion 40.

[0258] The housing 20 includes a housing body 21 and an end cover 22. The housing body 21 has an opening, and the end cover 22 is connected to the housing body 21 and covers the opening.

[0259] The electrode assembly 10 is accommodated in the housing 20. The electrode assembly 10 includes a positive electrode plate 11 and a negative electrode plate 12. The positive electrode plate 11 includes a positive electrode main body portion 111 and a plurality of positive electrode tabs 112. The positive electrode main body portion 111 is provided with a positive electrode active material layer 113, and the positive electrode tabs 112 extend from the edge of the positive electrode main body portion 111 toward the end cover 22. The negative electrode plate 12 includes a negative electrode main body portion 121 and a plurality of negative electrode tabs 122. The negative electrode main body portion 121 is provided with a negative electrode active material layer 123, and the negative electrode tabs 122 extend from the edge of the negative electrode main body portion 121 toward the end cover 22.

[0260] The positive electrode lead-out portion 30 includes a positive electrode terminal 31 and a positive electrode adapter piece 32. The positive electrode adapter piece 32 is welded to a plurality of positive electrode tabs 112 to form a first welding mark P1. The positive electrode terminal 31 is disposed on the end cover 22, and the positive electrode terminal 31 is welded to the positive electrode adapter piece 32 to form a third welding mark P3.

[0261] The negative electrode lead-out portion 40 includes a negative electrode terminal 41 and a negative electrode adapter piece 42. The negative electrode adapter piece 42 is welded to a plurality of negative electrode tabs 122 to form a second welding mark P2. The negative electrode terminal 41 is disposed on the end cover 22, and the negative electrode terminal 41 is welded to the negative electrode adapter piece 42 to form a fourth welding mark P4.

[0262] The positive electrode tab 112 includes a positive electrode connection portion 1121. One end of the positive electrode connection portion 1121 is connected to the positive electrode main body portion 111, and the other end is connected to the first welding mark P1. The negative electrode tab 122 includes a negative electrode connection portion 1221. One end of the negative electrode connection portion 1221 is connected to the negative electrode main body portion 121, and the other end is connected to the second welding mark P2. The sum of the minimum current-carrying cross-sectional areas of the positive electrode connection portions 1121 of the plurality of positive electrode tabs 112 is S1; the sum of the minimum current-carrying cross-sectional areas of the negative electrode connection portions 1221 of the plurality of negative electrode tabs 122 is S2.

[0263] The conductivity of the positive electrode tab 112 is σ c , and the conductivity of the negative electrode tab 122 is σ a .

[0264] S1 / S2 ≥ σ a / σ c .

[0265] The number of positive electrode tabs 112 of the electrode assembly 10 is m, and the minimum current-carrying cross-sectional area of the positive electrode connection portion 1121 is S 11 , and S1 = m × S 11 . The number of negative electrode tabs 122 of the electrode assembly 10 is n, and the minimum current-carrying cross-sectional area of the negative electrode connection portion 1221 is S 21 , and S2 = n × S 21 . m is greater than n.

[0266] The width of the positive electrode connection portion 1121 is greater than the width of the negative electrode connection portion 1221. The thickness of the positive electrode connection portion 1121 is greater than the thickness of the negative electrode connection portion 1221.

[0267] Although the present application has been described with reference to the preferred embodiments, various improvements can be made to it without departing from the scope of the present application, and components therein can be replaced with equivalents. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, Comprising: A housing; A positive electrode lead-out portion and a negative electrode lead-out portion, disposed on the housing; An electrode assembly, accommodated within the housing, the electrode assembly including a positive electrode sheet and a negative electrode sheet, the positive electrode sheet including a positive electrode main body portion and a positive electrode tab, the positive electrode main body portion being provided with a positive electrode active material layer, the positive electrode tab extending from the edge of the positive electrode main body portion, the negative electrode sheet including a negative electrode main body portion and a negative electrode tab, the negative electrode main body portion being provided with a negative electrode active material layer, the negative electrode tab extending from the edge of the negative electrode main body portion, the conductivity of the negative electrode tab being greater than that of the positive electrode tab, a plurality of the positive electrode tabs being welded to the positive electrode lead-out portion to form a first weld mark, and a plurality of the negative electrode tabs being welded to the negative electrode lead-out portion to form a second weld mark; Wherein, the positive electrode tab includes a positive electrode connection portion, one end of the positive electrode connection portion being connected to the positive electrode main body portion, and the other end being connected to the first weld mark; the negative electrode tab includes a negative electrode connection portion, one end of the negative electrode connection portion being connected to the negative electrode main body portion, and the other end being connected to the second weld mark; The sum of the minimum current-carrying cross-sectional areas of the positive electrode connection portions of the plurality of positive electrode tabs is S1; the sum of the minimum current-carrying cross-sectional areas of the negative electrode connection portions of the plurality of negative electrode tabs is S2; S1 is greater than S2.

2. The battery cell according to claim 1, characterized in that The conductivity of the positive electrode tab is σ c , and the conductivity of the negative electrode tab is σ a ; S1 / S2 ≥ σ a / σ c 。 3. The battery cell according to claim 1, wherein The total volume of the plurality of positive electrode connection portions is greater than or equal to the total volume of the plurality of negative electrode connection portions.

4. The battery cell according to claim 1, characterized in that, The positive electrode connection part has two first surfaces opposite to each other along its own thickness direction, and the area of the first surface is S c The negative electrode connection part has two second surfaces opposite to each other along its own thickness direction, and the area of the second surface is S a ; The thermal conductivity of the negative tab is greater than that of the positive tab, and S c is greater than S a .

5. The battery cell according to claim 1, characterized in that, The minimum width of the positive electrode connection portion is greater than the minimum width of the negative electrode connection portion.

6. The battery cell according to claim 1, characterized in that, The thickness of the positive electrode tab is greater than the thickness of the negative electrode tab.

7. The battery cell according to claim 1, characterized in that, The number of the positive electrode tabs is greater than the number of the negative electrode tabs.

8. The battery cell according to claim 1, wherein The area of the first weld mark is greater than the area of the second weld mark.

9. The battery cell according to claim 1, characterized in that, The positive electrode lead-out portion includes a positive electrode terminal and a positive electrode adapter plate, the positive electrode adapter plate being welded to the plurality of positive electrode tabs to form the first weld mark, the positive electrode terminal being disposed on the housing, and the positive electrode terminal being welded to the positive electrode adapter plate to form a third weld mark; The negative electrode lead-out portion includes a negative electrode terminal and a negative electrode adapter plate, the negative electrode adapter plate being welded to the plurality of negative electrode tabs to form the second weld mark, the negative electrode terminal being disposed on the housing, and the negative electrode terminal being welded to the negative electrode adapter plate to form a fourth weld mark.

10. The battery cell according to claim 9, wherein, The area of the third weld mark is greater than the area of the fourth weld mark.

11. The battery cell according to claim 9, wherein, The minimum current-carrying distance between the first weld mark and the third weld mark is less than the minimum current-carrying distance between the second weld mark and the fourth weld mark.

12. The battery cell according to claim 9, wherein, The volume of the positive electrode adapter plate is greater than or equal to the volume of the negative electrode adapter plate.

13. The battery cell according to claim 9, wherein, The minimum current-carrying cross-sectional area of the positive electrode terminal is greater than or equal to the minimum current-carrying cross-sectional area of the negative electrode terminal.

14. The battery cell according to claim 1, wherein The material of the positive electrode tab is aluminum, and the material of the negative electrode tab is copper.

15. The battery cell according to claim 1, characterized in that, The positive electrode sheet further includes a conductive layer coated on the positive electrode connection portion.

16. The battery cell according to claim 1, characterized in that, The average charging rate of the battery cell is K, satisfying K≥2.

17. A battery device, characterized in that, Including a plurality of battery cells according to any one of claims 1-16.

18. The battery device according to claim 17, wherein The battery device further includes a heat exchange member for exchanging heat with the positive electrode lead-out portion.

19. An electrical device, characterized in that, Including the battery device according to claim 17 or 18, the battery device being used for providing electric energy.

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