Battery cell, battery device and electric device

Abstract

Disclosed in the present application are a battery cell, a battery device and an electric device. The battery cell comprises a case, 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 disposed on the case. The electrode assembly is accommodated in the case. The electrode assembly comprises a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode body portion and positive electrode tabs, and the negative electrode sheet comprises a negative electrode body portion and negative electrode tabs. The electrical conductivity of the negative electrode tabs is greater than that of the positive electrode tabs. A plurality of positive electrode tabs are welded to the positive electrode lead-out portion to form a first weld mark, and a plurality of negative electrode tabs are welded to the negative electrode lead-out portion to form a second weld mark. Each positive electrode tab comprises a positive electrode connecting portion, one end of which is connected to the positive electrode body portion, and the other end of which is connected to the first weld mark. Each negative electrode tab comprises a negative electrode connecting portion, one end of which is connected to the negative electrode body portion, and the other end of which is connected to the second weld mark.

Description

Battery cell, battery device, and electric device

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application 202421830492.2, filed on July 31, 2024, entitled “Battery cell, battery device, and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of batteries, and in particular to a battery cell, a battery device, and an electric device. BACKGROUND

[0004] Battery cells are widely used in electronic devices, such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, and electric tools, etc.

[0005] In the development of battery technology, how to improve the cycle performance of battery cells is a research direction in battery technology. SUMMARY

[0006] The present application provides a battery cell, a battery device, and an electric device, which can improve the cycle performance.

[0007] 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 disposed in the housing. The electrode assembly is accommodated in the housing. The electrode assembly includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet 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 an edge of the positive electrode main body portion, the negative electrode sheet 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 an edge of the negative electrode main body portion. The electrical conductivity of the negative electrode tab is greater than the electrical conductivity 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, and 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 connecting portion, one end of the positive electrode connecting portion is connected to the positive electrode main body portion, and the other end of the positive electrode connecting portion is connected to the first welding mark. The negative electrode tab includes a negative electrode connecting portion, one end of the negative electrode connecting portion is connected to the negative electrode main body portion, and the other end of the negative electrode connecting portion is connected to the second welding mark. The sum of the minimum cross-sectional areas of the positive electrode connecting portions of the plurality of positive electrode tabs is S1; the sum of the minimum cross-sectional areas of the negative electrode connecting portions of the plurality of negative electrode tabs is S2; S1 is greater than S2.

[0008] In the embodiment of the present application, S1 is greater than S2, which can reduce the difference in overcurrent capacity between the plurality of positive connection portions and the plurality of negative connection portions caused by different conductivities, reduce the temperature difference between the positive connection portions and the negative connection portions, further reduce the temperature difference between the positive main body portion and the negative main body portion, and improve the cycle performance and cycle life of the battery monomer.

[0009] In some embodiments, the positive tab has an electrical conductivity of σ c , and the negative tab has an electrical conductivity of σ a . S1 / S2≥σ a / σ c . By setting S1 and S2 according to the electrical conductivity of the positive tab and the electrical conductivity of the negative tab, the difference in overcurrent capacity between the plurality of positive connection portions and the plurality of negative connection portions can be further reduced, the temperature difference between the positive connection portions and the negative connection portions can be reduced, and the temperature difference between the positive main body portion and the negative main body portion can be further reduced, thereby improving the cycle performance and cycle life of the battery monomer.

[0010] In some embodiments, the total volume of the plurality of positive connection portions is greater than or equal to the total volume of the plurality of negative connection portions. By increasing the total volume of the plurality of positive connection portions, the overcurrent capacity of the plurality of positive connection portions can be improved, and the difference in overcurrent capacity between the plurality of positive connection portions and the plurality of negative connection portions can be reduced.

[0011] In some embodiments, the positive connection portion has two first surfaces opposite in the thickness direction of the positive connection portion, and the area of the first surface is S c ; and the negative connection portion has two second surfaces opposite in the thickness direction of the negative connection portion, and the area of the second surface is S a . The thermal conductivity of the negative tab is greater than the thermal conductivity of the positive tab, and S c is greater than S a .

[0012] Compared with the negative tab, the positive tab has poor heat dissipation capacity. In the embodiment 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 when overcurrent occurs, reduce the temperature difference between the positive connection portion and the negative connection portion, improve the temperature consistency, and improve the cycle performance of the battery monomer.

[0013] In some embodiments, the minimum width of the positive connection portion is greater than the minimum width of the negative connection portion. Compared with the negative connection portion, the positive connection portion can have a larger width, so as to improve the overcurrent cross-sectional area and the heat dissipation area of the positive connection portion, reduce the difference in overcurrent capacity between the positive connection portion and the negative connection portion, reduce the temperature difference between the positive connection portion and the negative connection portion, improve the cycle performance of the battery monomer.

[0014] In some embodiments, the thickness of the positive tab is greater than the thickness of the negative tab. The positive tab can have a greater thickness than the negative tab, thereby increasing the cross-sectional area of the positive connection portion for current flow and the heat dissipation area, reducing the difference in current flow capacity between the positive connection portion and the negative connection portion, reducing the temperature difference between the positive connection portion and the negative connection portion, and improving the cycle performance of the battery cell.

[0015] In some embodiments, the number of positive tabs is greater than the number of negative tabs. The embodiments of the present application can increase the number of positive connection portions, reduce the difference in current flow capacity between the plurality of positive connection portions and the plurality of negative connection portions, reduce the temperature difference between the positive connection portions and the negative connection portions, and thereby reduce the temperature difference between the positive main body portion and the negative main body portion, and improve the cycle performance and cycle life of the battery cell.

[0016] In some embodiments, the area of the first weld is greater than the area of the second weld. The embodiments of the present application can increase the cross-sectional area of the first weld for current flow, reduce the difference in current flow capacity between the first weld and the second weld, increase the heat dissipation area of the first weld, reduce the temperature difference between the first weld and the second weld, and improve the cycle performance and cycle life of the battery cell.

[0017] In some embodiments, the positive lead-out portion includes a positive terminal and a positive adapter tab, the positive adapter tab is welded to the plurality of positive tabs and forms the first weld, and the positive terminal is disposed in the housing and is welded to the positive adapter tab and forms the third weld. The negative lead-out portion includes a negative terminal and a negative adapter tab, the negative adapter tab is welded to the plurality of negative tabs and forms the second weld, and the negative terminal is disposed in the housing and is welded to the negative adapter tab and forms the fourth weld.

[0018] In some embodiments, the area of the third weld is greater than the area of the fourth weld. The embodiments of the present application can further improve the current flow capacity on the positive current flow chain of the battery cell, reduce the difference in current flow capacity between the positive and negative, improve the consistency of current flow, and improve the cycle performance of the battery cell.

[0019] In some embodiments, the minimum current flow distance between the first weld and the third weld is less than the minimum current flow distance between the second weld and the fourth weld. The embodiments of the present application can shorten the conductive path on the positive current flow chain of the battery cell, reduce the resistance, reduce the difference in current flow capacity between the positive and negative, and improve the consistency of current flow.

[0020] In some embodiments, the volume of the positive adapter tab is greater than or equal to the volume of the negative adapter tab, to improve the current flow capacity of the positive adapter tab and increase the heat dissipation area of the positive adapter tab.

[0021] In some embodiments, the minimum cross-sectional area of the positive electrode terminal for current flow is greater than or equal to the minimum cross-sectional area of the negative electrode terminal for current flow. By increasing the cross-sectional area of the positive electrode terminal for current flow, the difference in current flow capacity between the positive electrode terminal and the negative electrode terminal can be reduced, and the temperature difference between the positive electrode terminal and the negative electrode terminal when an overcurrent flows can be reduced.

[0022] In some embodiments, the positive electrode tab is made of aluminum, and the negative electrode tab is made of copper. Both copper and aluminum have high thermal conductivity and electrical conductivity. Using an aluminum positive electrode tab and a copper negative electrode tab can improve the current flow capacity, reduce the temperature rise of the electrode assembly, and improve the cycle performance.

[0023] In some embodiments, the positive electrode tab further includes a conductive layer coated on the positive electrode connecting portion. By coating the conductive layer, the cross-sectional area for current flow can be increased, and the heat generation of the positive electrode connecting portion can be reduced.

[0024] In some embodiments, the average charge rate of the battery cell is K, which satisfies K≥2. The battery cell has a fast charging capability, which can save charging time and improve user experience.

[0025] In a second aspect, the embodiments of the present application provide a battery device, which includes a plurality of battery cells according to any one of the embodiments of the first aspect.

[0026] In some embodiments, the battery device further includes a heat exchange member, which is configured to exchange heat with the positive electrode lead-out portion.

[0027] In a third aspect, the embodiments of the present application provide an electrical device, which includes the battery device according to any one of the embodiments of the second aspect, and the battery device is configured to provide electrical energy. BRIEF DESCRIPTION OF DRAWINGS

[0028] The features, advantages, and technical effects of the exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0029] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application;

[0030] FIG. 2 is a schematic diagram of a battery device according to some embodiments of the present application;

[0031] FIG. 3 is an exploded schematic diagram of a battery cell according to some embodiments of the present application;

[0032] FIG. 4 is a schematic diagram of an electrode assembly of a battery cell according to some embodiments of the present application;

[0033] FIG. 5 is a schematic diagram of a positive electrode tab of a battery cell in a flattened state according to some embodiments of the present application;

[0034] FIG. 6 is a cross-sectional schematic diagram of FIG. 5 along the A-A direction;

[0035] FIG. 7 is a schematic view of a negative tab of a battery cell in a flattened state, according to some embodiments of the present application;

[0036] FIG. 8 is a cross-sectional view of FIG. 7 taken along the direction of B-B;

[0037] FIG. 9 is a cross-sectional view of a battery cell, according to some embodiments of the present application;

[0038] FIG. 10 is an enlarged view of box A of FIG. 9;

[0039] FIG. 11 is an enlarged view of box A of FIG. 9;

[0040] FIG. 12 is another cross-sectional view of a battery cell, according to some embodiments of the present application;

[0041] FIG. 13 is a schematic view of a battery cell during assembly, according to some embodiments of the present application;

[0042] FIG. 14 is an enlarged view of the circle box of FIG. 5;

[0043] FIG. 15 is an enlarged view of the circle box of FIG. 7;

[0044] FIG. 16 is a cross-sectional view of a positive tab of a battery cell, according to some other embodiments of the present application;

[0045] FIG. 17 is a schematic view of a battery device, according to some other embodiments of the present application.

[0046] The reference numerals are explained as follows: 1, vehicle; 2, battery device; 3, controller; 4, motor; 5, case; 5a, first case portion; 5b, second case portion; 6, battery cell; 7, heat exchange member; 10, electrode assembly; 10a, electrode main body; 11, positive electrode sheet; 111, positive electrode main portion; 112, positive electrode tab; 1121, positive electrode connecting portion; 1121a, first surface; 1122, first positive electrode portion; 1123, second positive electrode portion; 1124, positive electrode welding area; 113, positive electrode active material layer; 114, positive electrode current collector; 115, positive electrode coating area; 116, conductive layer; 12, negative electrode sheet; 121, negative electrode main portion; 122, negative electrode tab; 1221, negative electrode connecting portion; 1221a, second surface; 1222, first negative electrode portion; 1223, second negative electrode portion; 1224, negative electrode welding area; 123, negative electrode active material layer; 124, negative electrode current collector; 125, negative electrode coating area; 13, separator; 20, housing; 21, case body; 22, end cover; 221, positive electrode lead-out hole; 222, negative electrode lead-out hole; 30, positive electrode lead-out portion; 31, positive electrode terminal; 32, positive electrode adapter tab; 40, negative electrode lead-out portion; 41, negative electrode terminal; 42, negative electrode adapter tab; 50, first insulating member; 60, first fixing member; 70, second insulating member; 80, second fixing member; P1, first welding mark; P2, second welding mark; P3, third welding mark; P4, fourth welding mark; X, second direction; Y, third direction; Z, first direction. DETAILED DESCRIPTION

[0047] In order 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 drawings in the embodiments of the present application. Obviously, the described embodiments are only some, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the specification of the present application is only for the purpose of describing specific embodiments and is not intended to be limiting of the present application; the terms "include" and "have" and any variations thereof in the specification of the present application and the claims and the above description of drawings are intended to cover the non-exclusive inclusion; the terms "first", "second" and the like in the specification of the present application and the claims are used to distinguish different objects, but not to describe a particular order or a primary and secondary relationship.

[0049] Reference to "an embodiment" or "the embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" or "in the embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive.

[0050] In the description of the application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "attachment" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0051] The term "and / or" in the application is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the application generally represents that the front and rear associated objects have an "or" relationship.

[0052] In the embodiments of the application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the application shown in the drawings, and the overall thickness, length and width of the integrated device are only exemplary and should not constitute any limitation on the application.

[0053] "Multiple" appearing in the application means more than two (including two).

[0054] At present, from the development of market situation, the application of battery device is more and more widely. The battery device is not only applied to the energy storage power supply system of water power, fire power, wind power and solar power station, but also widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, and aerospace and other fields. With the continuous expansion of the application field of battery device, the market demand is also increasing.

[0055] The battery device generally refers to a single physical module including a plurality of battery monomers to provide higher voltage and capacity. The battery monomer can be the smallest unit constituting the battery device.

[0056] A battery cell includes an electrode assembly, which is a component in which electrochemical reactions occur in the battery cell. The electrode assembly includes a positive electrode tab and a negative electrode tab, which can transmit current during cycling of the battery cell. The positive electrode tab and the negative electrode tab generate heat when current flows through the positive electrode tab and the negative electrode tab; due to material or other reasons, the temperature of the positive electrode tab can be higher than that of the negative electrode tab, which affects the temperature consistency of the electrode assembly, causes the local temperature of the electrode assembly to be too high, and affects the cycling performance and cycle life of the battery cell.

[0057] In view of this, the application provides a technical solution, which differentiates the cross-sectional area of the positive electrode tab and the 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 cycling performance and cycle life of the battery cell.

[0058] The battery device described in the embodiments of the application is suitable for a power consumption device using the battery device. The power consumption 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 power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy, and an electric aircraft toy, and the like, and the spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, and the like.

[0059] The following embodiments are described by taking a vehicle as an example for convenience of description.

[0060] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the application.

[0061] As shown in FIG. 1, the vehicle 1 is internally provided with a battery device 2, which can be arranged at the bottom, the head or the tail of the vehicle 1. The battery device 2 can be used for power supply of the vehicle 1, for example, the battery device 2 can be used as an operating power source of the vehicle 1.

[0062] The vehicle 1 can further include a controller 3 and a motor 4, the controller 3 being used to control the battery device 2 to supply power to the motor 4, for example, for the working power demand of the vehicle 1 during starting, navigation and driving.

[0063] In some embodiments of the application, the battery device 2 can not only be used as an operating power source of the vehicle 1, but also be used as a driving power source of the vehicle 1, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1.

[0064] FIG. 2 is a schematic diagram of a battery device according to some embodiments of the application.

[0065] In some embodiments, the battery device 2 can include one or more battery cell assemblies for providing voltage and capacity.

[0066] The battery cell assembly can include a plurality of battery cells 6 connected in series, in parallel, or in a mixed connection through busbar components. The mixed connection means that there are both series and parallel connections among the plurality of battery cells 6.

[0067] The battery cell 6 can be a secondary battery cell, which means that the battery cell can be used continuously by activating the active material through charging after discharging the battery cell.

[0068] 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-hydrogen battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, or the like.

[0069] 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 including a square battery cell, a blade battery cell, a multi-prismatic battery cell, such as a hexagonal battery cell, or the like.

[0070] In some embodiments, the battery cell assembly is generally formed by arranging a plurality of battery cells 6; as an example, the battery cell assembly can be a battery module, which is formed by arranging and fixing a plurality of battery cells 6 into one independent module. As an example, the battery module can be formed by bundling a plurality of battery cells 6 with a cable tie.

[0071] In some embodiments, the battery device 2 can be a battery pack including a case 5 and one or more battery cell assemblies, which are accommodated in the case 5. As an example, the battery cell assembly can be a battery module, which can be accommodated in the case by fixing the battery module in the case. As an example, the battery cell assembly can also be accommodated in the case by directly fixing a plurality of battery cells 6 in the case.

[0072] In some embodiments, the case 5 for accommodating the battery cell 6 can be of various structures.

[0073] In some embodiments, the box 5 can include a first box part 5a and a second box part 5b, the first box part 5a and the second box part 5b are mutually coverable, and the first box part 5a and the second box part 5b together define a containing space for containing the battery cell 6. The second box part 5b can be a hollow structure with one end open, and the first box part 5a is a plate structure, which is coverable on the open end of the second box part 5b to form the box 5 with the containing space; or the first box part 5a and the second box part 5b can both be hollow structures with one side open, and the open end of the first box part 5a is coverable on the open end of the second box part 5b to form the box 5 with the containing space. Of course, the first box part 5a and the second box part 5b can have various shapes, such as a cylinder, a cuboid, etc.

[0074] In some embodiments, the box 5 can be part of the chassis structure of the vehicle. For example, part of the box 5 can be at least part of the floor of the vehicle, or part of the box 5 can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0075] In some embodiments, the battery device 2 can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0076] FIG. 3 is an exploded schematic view of a battery cell according to some embodiments of the present application; FIG. 4 is a schematic view of an electrode assembly of a battery cell according to some embodiments of the present application; FIG. 5 is a schematic view of a positive electrode sheet of a battery cell in a flattened state according to some embodiments of the present application, and FIG. 6 is a sectional view of FIG. 5 taken along the direction of A-A; FIG. 7 is a schematic view of a negative electrode sheet of a battery cell in a flattened state according to some embodiments of the present application, and FIG. 8 is a sectional view of FIG. 7 taken along the direction of B-B.

[0077] Referring to FIGS. 3 and 4, the battery cell includes a housing 20 and an electrode assembly 10, at least part of the electrode assembly 10 being contained in the housing 20.

[0078] The housing 20 is a hollow structure, and an internal space for containing the electrode assembly 10 and the electrolyte is formed inside the housing 20. 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.

[0079] In some embodiments, the housing 20 includes a shell 21 and an end cover 22, the shell 21 has an opening, and the end cover 22 is connected to the shell 21 and covers the opening;

[0080] The shell 21 is a component for cooperating with the end cover 22 to form an internal cavity of the battery cell 6, and the internal cavity formed can be used to contain the electrode assembly 10, the electrolyte, and other components.

[0081] The shell 21 and the end cover 22 can be separate components. In an example, an opening can be provided on the shell 21, and the end cover 22 can be used to cover the opening to form an internal cavity of the battery cell 6.

[0082] The shell 21 can have various shapes and sizes, such as a cuboid shape, a cylindrical shape, a hexagonal prism shape, etc. In particular, the shape of the shell 21 can be determined according to the specific shape and size of the electrode assembly 10. The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the present application does not make special limitations on this.

[0083] The end cover 22 can have a shape that is adapted to the shape of the shell 21 to fit the shell 21. The material of the end cover 22 can be the same as or different from the material of the shell 21. Alternatively, the end cover 22 can be made of a material with certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cover 22 is not easily deformed when subjected to extrusion and collision, and the battery cell 6 can have higher structural strength and improved reliability.

[0084] The end cover 22 can be connected to the shell 21 by welding, bonding, clamping, or other means.

[0085] The shell 21 can be open at one end or at both ends. In some examples, the shell 21 can have a structure that is open at one side, and the end cover 22 is provided as one and covers the shell 21. In other examples, the shell 21 can also have a structure that is open at both ends, and the end cover 22 is provided as two, and the two end covers 22 cover the two openings of the shell 21, respectively.

[0086] The electrode assembly 10 is a component in which electrochemical reactions occur in the battery cell 6. One or more electrode assemblies 10 can be contained in the shell 21.

[0087] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 11 and a negative electrode sheet 12. During charging and discharging of the battery cell 6, active ions (such as lithium ions) are inserted and extracted between the positive electrode sheet 11 and the negative electrode sheet 12.

[0088] In some embodiments, the electrode assembly 10 further includes a separator 13, which is arranged between the positive electrode sheet 11 and the negative electrode sheet 12, and can prevent short circuiting of the positive and negative electrodes while allowing the active ions to pass through.

[0089] In some embodiments, the electrode assembly 10 has a jelly-roll structure. The positive electrode sheet 11 and the negative electrode sheet 12 are wound into a jelly-roll structure.

[0090] In some embodiments, the electrode assembly 10 has a stacked structure.

[0091] As an example, the positive electrode sheet 11 and the negative electrode sheet 12 can each be provided in plural, and the plural positive electrode sheets 11 and the plural negative electrode sheets 12 can be alternately stacked.

[0092] As an example, the positive electrode sheet 11 can be provided in plural, and the negative electrode sheet 12 can be folded to form plural folded sections which are stacked. One positive electrode sheet 11 can be held between adjacent folded sections.

[0093] As an example, the positive electrode sheet 11 and the negative electrode sheet 12 can each be folded to form plural folded sections which are stacked.

[0094] As an example, the separator 13 can be provided in plural, and each of the plural separators 13 can be provided between any adjacent positive electrode sheet 11 or negative electrode sheet 12.

[0095] As an example, the separator 13 can be provided continuously, and can be provided between any adjacent positive electrode sheet 11 or negative electrode sheet 12 by folding or winding.

[0096] 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 an edge of the positive electrode main body portion 111.

[0097] The positive electrode tab 112 can be one or plural. As an example, in the electrode assembly 10 having a jelly-roll structure, the positive electrode tab 112 can be plural, and the plural positive electrode tabs 112 can be provided at intervals in the winding direction of the positive electrode sheet 11. As an example, in the electrode assembly 10 having a stack structure, the positive electrode tab 112 can be one or plural.

[0098] As an example, the positive electrode sheet 11 can 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 in the thickness direction thereof, and the positive electrode active material layer 113 is provided on either one or both of the two surfaces of the positive electrode current collector 114.

[0099] The positive electrode current collector 114 can include a positive electrode coated region 115 and the positive electrode tab 112. The positive electrode coated region 115 has a surface coated with the positive electrode active material layer 113, and the positive electrode tab 112 extends from an edge of the positive electrode coated region 115 and is provided protruding. The positive electrode main body portion 111 includes the positive electrode coated region 115 and the positive electrode active material layer 113. At least a portion of the positive electrode tab 112 is not coated with the positive electrode active material layer 113, for example, a root portion of the positive electrode tab 112 near the positive electrode coated region 115 can be coated with the positive electrode active material layer 113.

[0100] In some embodiments, the positive electrode current collector 114 can be a metal foil, for example, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon, carbon, nickel, or titanium, or the like.

[0101] As an example, the positive electrode active material layer 113 includes a positive electrode active material, which can include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each of them. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material can also be used. These positive electrode active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFeP04(also referred to simply 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 a composite material of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxide can include, but are not limited to, at least one of 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(also referred to simply as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to simply as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to simply as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to simply as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to simply as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2), and modified compounds thereof.

[0102] In some embodiments, the negative electrode tab 12 includes a negative electrode main portion 121 provided with a negative electrode active material layer 123 and a negative electrode ear 122 extending from an edge of the negative electrode main portion 121.

[0103] The negative tab 122 can be one or a plurality. As an example, in the electrode assembly 10 having a jelly-roll structure, the negative tab 122 can be a plurality, and the plurality of negative tabs 122 can be disposed at intervals in the winding direction of the negative sheet 12. As an example, in the electrode assembly 10 having a stack structure, the negative tab 122 can be one or a plurality.

[0104] As an example, the negative sheet 12 can include a negative current collector 124 and a negative active material layer 123 disposed on at least one surface of the negative current collector 124. The negative current collector 124 has two surfaces opposite in the thickness direction thereof, and the negative active material layer 123 is disposed on either one or both of the two surfaces of the negative current collector 124.

[0105] The negative current collector 124 can include a negative coated region 125, the surface of which is coated with the negative active material layer 123, and a negative tab 122 that extends from the edge of the negative coated region 125 and is protrusively disposed. The negative main body 121 includes the negative coated region 125 and the negative active material layer 123. At least a portion of the negative tab 122 is not coated with the negative active material layer 123, for example, the root portion of the negative tab 122 close to the negative coated region 125 can be coated with the negative active material layer 123.

[0106] In some embodiments, the positive main body 111, the negative main body 121, and the separator 13 constitute an electrode main body 10a of the electrode assembly 10. The positive tab 112 and the negative tab 122 are drawn out from the electrode main body 10a. The positive tab 112 and the negative tab 122 can be drawn out from the same end of the electrode main body 10a, or can be drawn out from the two ends of the electrode main body 10a, respectively.

[0107] In some embodiments, the negative current collector 124 can employ a metal foil, for example, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, a carbon-nickel composite, a carbon-titanium composite, and the like.

[0108] In some embodiments, the negative active material layer 123 includes a negative active material. For example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, lithium titanate, and the like. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy.

[0109] In some embodiments, the material of the positive current collector 114 can be aluminum, and the material of the negative current collector 124 can be copper.

[0110] 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 the respective layers can be the same or different. The separator 13 can be a separate member provided 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.

[0111] In some embodiments, the battery cell 6 includes a positive electrode lead-out portion 30 connected to the positive electrode tab 112 and a negative electrode lead-out portion 40 connected to the negative electrode tab 122.

[0112] The positive electrode lead-out portion 30 and the negative electrode lead-out portion 40 are used to be electrically connected to an external circuit to enable charging or discharging of the battery cell 6.

[0113] In some embodiments, the positive electrode lead-out portion 30 includes a positive electrode terminal 31. At least a portion of the positive electrode terminal 31 is exposed to the outside of the battery cell 6 to facilitate connection to a bus member.

[0114] As an example, the positive electrode terminal 31 can be a separately formed member that is mounted to the case 20. Alternatively, the positive electrode terminal 31 can also be a part of the case 20.

[0115] 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, such as a positive electrode adapter tab 32, that connect the positive electrode terminal 31 and the positive electrode tab 112.

[0116] In some embodiments, the positive electrode terminal 31 is connected to the end cover 22 by welding, riveting, clamping, or other means.

[0117] In some embodiments, the negative electrode lead-out portion 40 includes a negative electrode terminal 41. At least a portion of the negative electrode terminal 41 is exposed to the outside of the battery cell 6 to facilitate connection to a bus member.

[0118] As an example, the negative electrode terminal 41 can be a separately formed member that is mounted to the case 20. Alternatively, the negative electrode terminal 41 can also be a part of the case 20.

[0119] 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, such as a negative electrode adapter tab 42, that connect the negative electrode terminal 41 and the negative electrode tab 122.

[0120] In some embodiments, the negative electrode terminal 41 is connected to the end cover 22 by welding, riveting, clamping, or other means.

[0121] Figure 9 is a cross-sectional view of a battery cell according to some embodiments of the present application; Figure 10 is an enlarged view of the area A in Figure 9; Figure 11 is an enlarged view of the area A in Figure 9; Figure 12 is another cross-sectional view of a battery cell according to some embodiments of the present application; Figure 13 is a schematic view of a battery cell during assembly according to some embodiments of the present application; Figure 14 is an enlarged view of the circle in Figure 5; and Figure 15 is an enlarged view of the circle in Figure 7.

[0122] Referring to Figures 3 to 15, the battery cell 6 according to some embodiments of the present application comprises an electrode assembly 10, a housing 20, a positive electrode lead 30 and a negative electrode lead 40. The positive electrode lead 30 and the negative electrode lead 40 are provided on the housing 20. The electrode assembly 10 is housed in the housing 20. The electrode assembly 10 comprises a positive electrode tab 11 and a negative electrode tab 12. The positive electrode tab 11 comprises a positive electrode body 111 and a positive electrode ear 112. The positive electrode body 111 is provided with a positive electrode active material layer 113. The positive electrode ear 112 extends from an edge of the positive electrode body 111. The negative electrode tab 12 comprises a negative electrode body 121 and a negative electrode ear 122. The negative electrode body 121 is provided with a negative electrode active material layer 123. The negative electrode ear 122 extends from an edge of the negative electrode body 121. A plurality of the positive electrode ears 112 of the electrode assembly 10 are welded to the positive electrode lead 30 and form a first weld P1. A plurality of the negative electrode ears 122 of the electrode assembly 10 are welded to the negative electrode lead 40 and form a second weld P2.

[0123] The electrical conductivity of the negative electrode ear 122 is greater than the electrical conductivity of the positive electrode ear 112.

[0124] The positive electrode ear 112 comprises a positive electrode connecting portion 1121. One end of the positive electrode connecting portion 1121 is connected to the positive electrode body 111 and the other end of the positive electrode connecting portion 1121 is connected to the first weld P1. The negative electrode ear 122 comprises a negative electrode connecting portion 1221. One end of the negative electrode connecting portion 1221 is connected to the negative electrode body 121 and the other end of the negative electrode connecting portion 1221 is connected to the second weld P2. The sum of the minimum cross-sectional areas of the plurality of positive electrode connecting portions 1121 of the positive electrode ears 112 is S1. The sum of the minimum cross-sectional areas of the plurality of negative electrode connecting portions 1221 of the negative electrode ears 122 is S2. S1 is greater than S2.

[0125] The electrode assembly 10 can be one or more. As an example, there are two electrode assemblies 10. A plurality of the positive electrode ears 112 of one electrode assembly 10 are welded to the positive electrode lead 30 and form one first weld P1. A plurality of the positive electrode ears 112 of the other electrode assembly 10 are welded to the positive electrode lead 30 and form another first weld P1. A plurality of the negative electrode ears 122 of one electrode assembly 10 are welded to the negative electrode lead 40 and form one second weld P2. A plurality of the negative electrode ears 122 of the other electrode assembly 10 are welded to the negative electrode lead 40 and form another second weld P2.

[0126] As an example, the size relationship of S1 and S2 is for the same electrode assembly 10 when the electrode assembly 10 is plural.

[0127] As an example, in the width direction X1 of the positive tab 112, the size of the positive connecting portion 1121 can be greater than or equal to the size of the first weld P1. In the width direction X1 of the positive tab 112, the positive connecting portion 1121 can extend to both edges of the positive tab 112.

[0128] As an example, in the width direction X2 of the negative tab 122, the size of the negative connecting portion 1221 can be greater than or equal to the size of the second weld P2. In the width direction X2 of the negative tab 122, the negative connecting portion 1221 can extend to both edges of the negative tab 122.

[0129] As an example, the overcurrent cross section of the positive connecting portion 1121 can be a cross section perpendicular to the extension direction of the positive tab 112. After the positive tab 112 is flattened, the overcurrent cross section of the positive connecting portion 1121 is parallel to the thickness direction and the width direction of the positive tab 112. The minimum overcurrent cross-sectional area of the positive connecting portion 1121 is the area of the smallest overcurrent cross section of the positive connecting portion 1121.

[0130] As an example, the overcurrent cross section of the negative connecting portion 1221 can be a cross section perpendicular to the extension direction of the negative tab 122. After the negative tab 122 is flattened, the overcurrent cross section of the negative connecting portion 1221 is parallel to the thickness direction and the width direction of the negative tab 122. The minimum overcurrent cross-sectional area of the negative connecting portion 1221 is the area of the smallest overcurrent cross section of the negative connecting portion 1221.

[0131] In the electrode assembly 10, the minimum overcurrent cross-sectional areas of the positive connecting portions 1121 of the plurality of positive tabs 112 can be the same or different. As an example, the number of positive tabs 112 of the electrode assembly 10 is m, and the minimum overcurrent cross-sectional area of the positive connecting portion 1121 is S1. 11 , S1 = m x S 11 .

[0132] In the electrode assembly 10, the minimum overcurrent cross-sectional areas of the negative connecting portions 1221 of the plurality of negative tabs 122 can be the same or different. As an example, the number of negative tabs 122 of the electrode assembly 10 is n, and the minimum overcurrent cross-sectional area of the negative connecting portion 1221 is S2. 21 , S2 = n x S 21 . m can be greater than, equal to, or less than n.

[0133] During the circulation of the battery cell 6, the positive electrode connecting part 1121 and the negative electrode connecting part 1221 play a role of collecting and transmitting current, and the positive electrode connecting part 1121 and the negative electrode connecting part 1221 generate heat when current passes through; the positive electrode connecting part 1121 and the negative electrode connecting part 1221 are directly connected with the positive electrode main body part 111 and the negative electrode main body part 121 respectively, and the heat generated by the positive electrode connecting part 1121 and the negative electrode connecting part 1221 will affect the circulation performance of the battery cell 6.

[0134] In the embodiments of the present application, S1 is greater than S2, so as to reduce the difference in overcurrent capacity between the plurality of positive electrode connecting parts 1121 and the plurality of negative electrode connecting parts 1221 caused by different electrical conductivities, reduce the temperature difference between the positive electrode connecting part 1121 and the negative electrode connecting part 1221, and further reduce the temperature difference between the positive electrode main body part 111 and the negative electrode main body part 121, thereby improving the circulation performance and the cycle life of the battery cell 6.

[0135] In some embodiments, the positive electrode terminal 31 and the negative electrode terminal 41 are both arranged on the end cover 22. As an example, the end cover 22, the positive electrode terminal 31 and the negative electrode terminal 41 can be pre-assembled together, and then assembled with the electrode assembly 10 and the shell 21.

[0136] By way of example, the battery cell 6 comprises an end cover assembly, and the end cover assembly comprises the end cover 22, the positive electrode terminal 31 and the negative electrode terminal 41. Optionally, the positive electrode terminal 31 and the negative electrode terminal 41 are both arranged in an insulating manner with the end cover 22. Optionally, the positive electrode terminal 31 is riveted to the end cover 22, and the negative electrode terminal 41 is riveted to the end cover 22.

[0137] In some embodiments, the positive electrode tab 112 extends from one end of the positive electrode main body part 111 along the first direction Z.

[0138] 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.

[0139] Optionally, the first direction Z, the second direction X and the third direction Y are perpendicular to each other, and the third direction Y can be parallel to the thickness direction of the battery cell 6.

[0140] In some embodiments, the electrode main body 10a and the first welding mark P1 are arranged in a spaced manner along the first direction Z, and the positive electrode connecting part 1121 is arranged in a bent manner. By bending the positive electrode connecting part 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.

[0141] In some embodiments, in the width direction X1 of the positive electrode tab 112, both ends of the positive electrode connecting part 1121 exceed the first welding mark P1.

[0142] Exemplarily, the positive tab 112 further comprises two first positive portions 1122, which are respectively located on two sides of the first welding point P1 and connected to the first welding point P1 in the width direction X1 of the positive tab 112. The positive connecting portion 1121 is connected to the two first positive portions 1122 and the first welding point P1 away from one end of the positive main portion 111.

[0143] Exemplarily, the positive tab 112 further comprises a second positive portion 1123 connected to the two first positive portions 1122 and the first welding point P1. In the extension direction of the positive tab 112, the first positive portion 1122 connects the positive connecting portion 1121 and the second positive portion 1123.

[0144] As an example, FIG. 14 shows the state of the positive tab before welding. In FIG. 14, the area enclosed by the rectangular dashed line frame can be the positive welding area 1124 of the positive tab 112. When the plurality of positive tabs 112 are welded with the positive lead-out portion 30, the positive welding areas 1124 of the plurality of positive tabs 112 melt and form the first welding point P1 after solidification.

[0145] The positive welding area 1124 and the two first positive portions 1122 form a middle region of the positive tab 112; in the extension direction of the positive tab 112, the positive connecting portion 1121, the middle region of the positive tab 112 and the second positive portion 1123 are sequentially arranged.

[0146] In some embodiments, in the width direction X1 of the positive tab 112, the minimum width of the positive connecting portion 1121 is W1. The thickness of the positive tab 112 is T1. 11 =W1xT1.

[0147] In some embodiments, the negative tab 122 extends from one end of the negative main portion 121 in the first direction Z.

[0148] In some embodiments, the width direction X2 of the negative tab 122 is parallel to the width direction X1 of the positive tab 112.

[0149] In some embodiments, the electrode main body 10a and the second welding point P2 are arranged in the first direction Z with a space, and the negative connecting portion 1221 is arranged in a bent manner. By bending the negative connecting portion 1221, the space occupied by the negative tab 122 in the first direction Z can be saved, and the space utilization rate can be improved.

[0150] In some embodiments, in the width direction X2 of the negative tab 122, both ends of the negative connecting portion 1221 exceed the second welding point P2.

[0151] Exemplarily, the negative tab 122 further comprises two first negative portions 1222, which are respectively located on two sides of the second welding pad P2 in the width direction X2 of the negative tab 122 and connected to the second welding pad P2. The negative connecting portion 1221 is connected to the two first negative portions 1222 and the second welding pad P2 away from one end of the negative main portion 121.

[0152] Exemplarily, the negative tab 122 further comprises a second negative portion 1223 connected to the two first negative portions 1222 and the second welding pad P2. In the extension direction of the negative tab 122, the first negative portion 1222 connects the negative connecting portion 1221 and the second negative portion 1223.

[0153] As an example, FIG. 15 shows the state of the negative tab 122 before welding. In FIG. 15, the area enclosed by the rectangular dashed line frame can be the negative welding area 1224 of the negative tab 122. When the plurality of negative tabs 122 are welded with the negative lead-out portion 40, the negative welding areas 1224 of the plurality of negative tabs 122 melt and form the second welding pad P2 after solidification.

[0154] The negative welding area 1224 and the two first negative portions 1222 form a middle region of the negative tab 122; in the extension direction of the negative tab 122, the negative connecting portion 1221, the middle region of the negative tab 122 and the second negative portion 1223 are sequentially arranged.

[0155] In some embodiments, in the width direction X2 of the negative tab 122, the minimum width of the negative connecting portion 1221 is W2. The thickness of the negative tab 122 is T2. 21 = W2 x T2.

[0156] In some embodiments, the electrical conductivity of the positive tab 112 is σ c , and the electrical conductivity of the negative tab 122 is σ a . S1 / S2≥ σ a / σ c .

[0157] The embodiments of the present application set S1 and S2 according to the electrical conductivity of the positive tab 112 and the electrical conductivity of the negative tab 122, which can further reduce the difference in overcurrent capacity between the plurality of positive connecting portions 1121 and the plurality of negative connecting portions 1221, reduce the temperature difference between the positive connecting portion 1121 and the negative connecting portion 1221, and further reduce the temperature difference between the positive main portion 111 and the negative main portion 121, thereby improving the cycle performance and cycle life of the battery monomer 6.

[0158] 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.

[0159] In some embodiments, σ c is 2 x 10 7 S / m - 5 x 10 7 S / m. Illustratively, σ c is 3.77 x 10 7 S / m.

[0160] In some embodiments, σ a is 4 x 10 7 S / m - 7 x 10 7 S / m. Illustratively, σ c is 5.85 x 10 7 S / m.

[0161] In some embodiments, the total volume V1 of the plurality of positive electrode connecting portions 1121 is greater than or equal to the total volume V2 of the plurality of negative electrode connecting portions 1221. By increasing the total volume of the plurality of positive electrode connecting portions 1121, the overcurrent capacity of the plurality of positive electrode connecting portions 1121 can be improved, and the difference in overcurrent capacity between the plurality of positive electrode connecting portions 1121 and the plurality of negative electrode connecting portions 1221 can be reduced.

[0162] In some embodiments, the positive electrode connecting portion 1121 has two first surfaces 1121a opposite along the thickness direction of the positive electrode connecting portion 1121, and the area of the first surface 1121a is S c ; and the negative electrode connecting portion 1221 has two second surfaces 1221a opposite along the thickness direction of the negative electrode connecting portion 1221, and the area of the second surface 1221a is S a . The thermal conductivity of the negative tab 122 is greater than the thermal conductivity of the positive tab 112, and S c is greater than S a .

[0163] As an example, the positive electrode connecting portion 1121 is bent; correspondingly, the first surface 1121a is also bent to be a curved surface. Optionally, S c may be measured and calculated when the positive electrode connecting portion 1121 is in a flat state.

[0164] As an example, the areas S c of the first surfaces 1121a of the positive electrode connecting portions 1121 of the plurality of positive tabs 112 can be different. Specifically, the plurality of positive tabs 112 need to be gathered together before being welded with the positive lead-out portion 30; after welding, the extension lengths of the positive electrode connecting portions 1121 of the plurality of positive tabs 112 can be different, thereby causing the areas S c of the first surfaces 1121a of the plurality of positive electrode connecting portions 1121 to be different.

[0165] As an example, the negative electrode connecting portion 1221 is bent; correspondingly, the second surface 1221a is also bent to be a curved surface. Optionally, Sa The measurement and calculation can be performed when the negative connection portion 1221 is in the flattened state.

[0166] As an example, the area S a may be different. Specifically, the plurality of negative tabs 122 need to be first gathered together before being welded with the negative lead-out portion 40; after welding, the extension lengths of the negative connection portions 1221 of the plurality of negative tabs 122 can be different, thereby causing the areas S a to be different.

[0167] Compared with the negative tab 122, the positive tab 112 has poor heat conduction ability; the embodiment of the present application makes S c greater than S a , so as to increase the heat dissipation area of the positive tab 112, reduce the temperature rise of the positive tab 112 under overcurrent, reduce the temperature difference between the positive connection portion 1121 and the negative connection portion 1221, improve the temperature consistency, and improve the cycle performance of the battery monomer 6.

[0168] In some embodiments, the volume V c of the positive connection portion 1121 is S c × T1.

[0169] In some embodiments, the volume V a of the negative connection portion 1221 is S a × T2.

[0170] In some embodiments, V c / V a ≥ σ a / σ c .

[0171] In some embodiments, the minimum width W1 of the positive connection portion 1121 is greater than the minimum width W2 of the negative connection portion 1221.

[0172] Compared with the negative connection portion 1221, the positive connection portion 1121 can have a larger width, thereby improving the overcurrent cross-sectional area and heat dissipation area of the positive connection portion 1121, reducing the difference in overcurrent capacity between the positive connection portion 1121 and the negative connection portion 1221, reducing the temperature difference between the positive connection portion 1121 and the negative connection portion 1221, and improving the cycle performance of the battery monomer 6.

[0173] In some embodiments, the thickness T1 of the positive tab 112 is greater than the thickness T2 of the negative tab 122.

[0174] Compared with the negative tab 122, the positive tab 112 can have a larger thickness, so as to increase the flow area and heat dissipation area of the positive connecting part 1121, reduce the difference in flow capacity between the positive connecting part 1121 and the negative connecting part 1221, reduce the temperature difference between the positive connecting part 1121 and the negative connecting part 1221, and improve the cycle performance of the battery cell 6.

[0175] In some embodiments, the thickness T1 of the positive tab 112 is 10-15 μm, and can be 12-15 μm. For example, 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 defined by any two of the above values.

[0176] In some embodiments, the thickness T2 of the negative tab 122 is 5-12 μm, and can be 6-10 μm. For example, T1 is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, or a range defined by any two of the above values.

[0177] In some embodiments, the number m of the positive tabs 112 is greater than the number n of the negative tabs 122.

[0178] The m positive tabs 112 are stacked, and the n negative tabs 122 are stacked.

[0179] The embodiments of the present application can increase the positive connecting part 1121, reduce the difference in flow capacity between the plurality of positive connecting parts 1121 and the plurality of negative connecting parts 1221, reduce the temperature difference between the positive connecting part 1121 and the negative connecting part 1221, further reduce the temperature difference between the positive main body part 111 and the negative main body part 121, and improve the cycle performance and cycle life of the battery cell 6.

[0180] In some embodiments, m / n≥σ a / σ c .

[0181] The embodiments of the present application set m and n according to the electrical conductivity of the positive tab 112 and the electrical conductivity of the negative tab 122, which can further reduce the difference in flow capacity between the plurality of positive connecting parts 1121 and the plurality of negative connecting parts 1221, reduce the temperature difference between the positive connecting part 1121 and the negative connecting part 1221, further reduce the temperature difference between the positive main body part 111 and the negative main body part 121, and improve the cycle performance and cycle life of the battery cell 6.

[0182] In some embodiments, the electrode assembly 10 is a jelly-roll structure. The positive electrode main body 111 has M layers stacked in the third direction Y, and the negative electrode main body 121 has N layers stacked in the third direction Y.

[0183] In some embodiments, 1 / 2≤m / M≤1, and optionally, 5 / 8≤m / M≤3 / 4. The positive electrode tab 112 has a larger number, thereby improving the overcurrent capacity, reducing the temperature rise of the positive electrode tab 112, and improving the fast charging capability of the battery cell 6. When the overcurrent capacity meets the requirements, m / M≤3 / 4 can reduce the increase in the number of positive electrode tabs 112 and reduce the impact on the energy density.

[0184] In some embodiments, 1 / 2≤n / N≤1, and optionally, 5 / 8≤n / N≤3 / 4. The negative electrode tab 122 has a larger number, thereby improving the overcurrent capacity, reducing the temperature rise of the negative electrode tab 122, and improving the fast charging capability of the battery cell 6. When the overcurrent capacity meets the requirements, n / N≤3 / 4 can reduce the increase in the number of negative electrode tabs 122 and reduce the impact on the energy density.

[0185] In some embodiments, the area S c1 of the first welding mark P1 is greater than the area S a1 of the second welding mark P2.

[0186] 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 taken as the area of the first welding mark P1.

[0187] 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 taken as the area of the second welding mark P2.

[0188] The embodiments of the present application can increase the overcurrent cross-sectional area of the first welding mark P1, reduce the difference in overcurrent 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.

[0189] 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.

[0190] In some embodiments, the first welding mark P1 includes one or more first strip-shaped welding marks extending in the second direction X. The second welding mark P2 includes one or more second strip-shaped welding marks extending in the second direction X.

[0191] Optionally, the first strip-shaped weld in the second direction X has a larger size than the second strip-shaped weld in the second direction X.

[0192] In some embodiments, the positive electrode lead-out portion 30 includes a positive electrode terminal 31 and a positive electrode tab 32, the positive electrode tab 32 is welded to the plurality of positive electrode tabs 112 and forms the first weld P1, and the positive electrode terminal 31 is disposed on the housing 20 and is welded to the positive electrode tab 32 and forms the third weld P3.

[0193] In some embodiments, the positive electrode tab 32 and the plurality of positive electrode tabs 112 form the first weld P1 by ultrasonic welding. The positive electrode terminal 31 and the positive electrode tab 32 form the third weld P3 by laser welding.

[0194] In some embodiments, the positive electrode terminal 31 is disposed on the end cover 22.

[0195] Exemplarily, the end cover 22 is provided with a positive electrode lead-out hole 221, the positive electrode lead-out hole 221 penetrates the end cover 22 along the thickness direction of the end cover 22. The positive electrode terminal 31 is disposed on the positive electrode lead-out hole 221.

[0196] In some embodiments, at least part of the positive electrode terminal 31 is located outside the end cover 22 and covers the positive electrode lead-out hole 221.

[0197] In some embodiments, the entire positive electrode terminal 31 is located outside the end cover 22. Alternatively, at least part of the positive electrode terminal 31 can be accommodated in the positive electrode lead-out hole 221, for example, the positive electrode terminal 31 penetrates the positive electrode lead-out hole 221 and is riveted to the end cover 22.

[0198] 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 with the positive electrode terminal 31, and the first fixing member 60 is connected to the end cover 22 and the first insulating member 50 to fix the positive electrode terminal 31 to the end cover 22 through the first insulating member 50.

[0199] Optionally, a part of the first fixing member 60 is embedded in the first insulating member 50.

[0200] In some embodiments, the negative electrode lead-out portion 40 includes a negative electrode terminal 41 and a negative electrode tab 42, the negative electrode tab 42 is welded to the plurality of negative electrode tabs 122 and forms the second weld P2, and the negative electrode terminal 41 is disposed on the housing 20 and is welded to the negative electrode tab 42 and forms the fourth weld P4.

[0201] In some embodiments, the negative electrode tab 42 and the plurality of negative electrode tabs 122 form the second weld P2 by ultrasonic welding. The negative electrode terminal 41 and the negative electrode tab 42 form the fourth weld P4 by laser welding.

[0202] In some embodiments, the negative terminal 41 is provided to the end cover 22.

[0203] Exemplarily, the end cover 22 is provided with a negative lead-out hole 222, which penetrates the end cover 22 along the thickness direction of the end cover 22. The negative terminal 41 is provided to the negative lead-out hole 222.

[0204] In some embodiments, at least part of the negative terminal 41 is located outside the end cover 22 and covers the negative lead-out hole 222.

[0205] In some embodiments, the whole of the negative terminal 41 is located outside the end cover 22. Alternatively, at least part of the negative terminal 41 can be accommodated in the negative lead-out hole 222, for example, the negative terminal 41 penetrates the negative lead-out hole 222 and is riveted to the end cover 22.

[0206] In some embodiments, the battery cell 6 comprises 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 with the negative terminal 41, and the second fixing member 80 is connected to the end cover 22 and the second insulating member 70 to fix the negative terminal 41 to the end cover 22 through the second insulating member 70.

[0207] Optionally, part of the second fixing member 80 is embedded in the second insulating member 70.

[0208] In some embodiments, the area of the third welding mark P3 is greater than the area of the fourth welding mark P4.

[0209] Exemplarily, the third welding mark P3 has a third welding surface facing the electrode body 10a, which is formed on the positive adapter tab 32. The area of the third welding surface can be taken as the area of the third welding mark P3.

[0210] Exemplarily, the fourth welding mark P4 has a fourth welding surface facing the electrode body 10a, which is formed on the negative adapter tab 42. The area of the fourth welding surface can be taken as the area of the fourth welding mark P4.

[0211] 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 between the positive and negative overcurrent capacities, improve the overcurrent consistency, and improve the cycle performance of the battery cell 6.

[0212] In some embodiments, the volume of the positive adapter tab 32 is greater than or equal to the volume of the negative adapter tab 42, so as to improve the overcurrent capacity of the positive adapter tab 32 and increase the heat dissipation area of the positive adapter tab 32.

[0213] 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.

[0214] As an example, the positive tab 32 has two surfaces opposite along the thickness direction of the positive tab 32, one of which faces the positive terminal 31, and the other of which faces the positive tab 112. The minimum overcurrent distance between the first solder print P1 and the third solder print P3 can refer to the minimum distance of current flowing from the first solder print P1 to the third solder print P3 along the surface of the positive tab 32 facing the positive tab 112.

[0215] As an example, the negative tab 42 has two surfaces opposite along the thickness direction of the negative tab 42, one of which faces the negative terminal 41, and the other of which faces the negative tab 122. The minimum overcurrent distance between the second solder print P2 and the fourth solder print P4 can refer to the minimum distance of current flowing from the second solder print P2 to the fourth solder print P4 along the surface of the negative tab 42 facing the negative tab 122.

[0216] Embodiments of the present application can shorten the conductive path on the positive overcurrent chain of the battery cell 6, reduce the resistance, reduce the difference in positive and negative overcurrent capacity, and improve the overcurrent consistency.

[0217] In some embodiments, the minimum overcurrent cross-sectional area of the positive terminal 31 is greater than or equal to the minimum overcurrent cross-sectional area of the negative terminal 41.

[0218] As an example, the minimum overcurrent cross-sectional area of the positive terminal 31 can be the area of the smallest cross section of the positive terminal 31 perpendicular to the axial direction of the positive lead-out hole 221. The minimum overcurrent cross-sectional area of the negative terminal 41 can be the area of the smallest cross section of the negative terminal 41 perpendicular to the axial direction of the negative lead-out hole 222.

[0219] Embodiments of the present application can reduce the difference in overcurrent capacity between the positive terminal 31 and the negative terminal 41 by increasing the overcurrent area of the positive terminal 31, and reduce the temperature difference between the positive terminal 31 and the negative terminal 41 when overcurrent occurs.

[0220] In some embodiments, the positive tab 112 is made of aluminum, and the negative tab 122 is made of copper. Both copper and aluminum have high thermal conductivity and electrical conductivity. Using aluminum positive tabs 112 and copper negative tabs 122 can improve overcurrent capacity, reduce the temperature rise of the electrode assembly 10, and improve cycle performance.

[0221] Compared with copper, aluminum has higher resistance and thermal resistance; embodiments of the present application make S1 greater than S2 to reduce the resistance difference and thermal resistance difference between the plurality of positive connection portions 1121 and the plurality of negative connection portions 1221, improve the consistency of positive and negative overcurrent capacity and temperature rise, and improve cycle performance.

[0222] In some embodiments, the positive tab 32 is made of aluminum or aluminum alloy. The negative tab 42 is made of copper or copper alloy.

[0223] In some embodiments, the material of the positive terminal 31 is aluminum or an aluminum alloy.

[0224] In some embodiments, the negative terminal 41 can be a copper-aluminum composite structure. For example, the material of the part of the negative terminal 41 connected to the negative tab 42 is copper.

[0225] In some embodiments, the volume of the positive terminal 31 is greater than the volume of the negative terminal 41.

[0226] 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.

[0227] The battery cell 6 of the embodiments of the present application has fast charging capability.

[0228] In some embodiments, the charging time of the battery cell 6 from 10% SOC to 80% SOC under room temperature conditions is less than or equal to 16 minutes.

[0229] As an example, the room temperature can be an ambient temperature of 30°C.

[0230] SOC refers to the state of charge of the battery cell 6.

[0231] For example, 100% SOC and 0% SOC are defined as follows: the battery cell is charged to the upper limit voltage of the battery charge at a constant current charging rate of 0.33C, and then charged at a constant voltage of 0.05C, corresponding to the state of 100% SOC of the battery cell; the battery cell is discharged to the cut-off voltage at a constant current discharge rate of 0.33C, corresponding to the state of 0% SOC of the battery cell. For example, the upper limit voltage of the battery charge and the discharge cut-off voltage can be marked on the outer packaging film of the battery cell.

[0232] For example, 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.

[0233] In the embodiments of the present application, the battery cell 6 has fast charging capability, which can save charging time and improve user experience.

[0234] In some embodiments, the positive tab 112 and the negative tab 122 extend from the same end of the electrode body 10a along the first direction Z.

[0235] In the second direction X, the projection of the positive tab 112 along the third direction Y is arranged apart from the projection of the negative tab 122 along the third direction Y.

[0236] FIG. 16 is a schematic cross-sectional view of a positive tab of a battery cell according to some embodiments of the present application.

[0237] Referring to FIG. 16, in some embodiments, the positive tab 11 further comprises a conductive layer 116 coated on the positive connecting portion 1121.

[0238] As an example, the conductive layer 116 can be coated only on the root region of the positive connecting portion 1121 close to the positive main portion 111.

[0239] By coating the conductive layer 116, the present embodiments can increase the overcurrent area and reduce the heat generation of the positive connecting portion 1121.

[0240] FIG. 17 is a schematic view of a battery device according to some embodiments of the present application.

[0241] Referring to FIG. 17, in some embodiments, the battery device 2 comprises a plurality of battery cells 6.

[0242] In some embodiments, the battery device 2 further comprises a heat exchange member 7, which is configured to exchange heat with the positive lead-out portion 30.

[0243] As an example, the heat exchange member 7 comprises a heat exchange pipe.

[0244] The heat exchange member 7 can exchange heat with the positive lead-out portion 30 directly or indirectly through other heat conduction structures.

[0245] The heat exchange member 7 can exchange heat with the negative lead-out portion 40 or not.

[0246] The heat exchange member 7 can exchange heat with the positive tab 112 through the positive lead-out portion 30, thereby reducing the temperature rise of the positive tab 112 and improving the cycle performance of the battery cell 6.

[0247] According to some embodiments of the present application, the present application further provides a power consuming device, which comprises the battery device of any of the above embodiments and is configured to be powered by the battery device. The power consuming device can be any of the devices or systems described above.

[0248] Referring to FIGS. 3-15, the present embodiments provide a battery cell 6, which comprises an electrode assembly 10, a housing 20, a positive lead-out portion 30, and a negative lead-out portion 40.

[0249] The housing 20 comprises a shell 21 having an opening and an end cover 22 connected to the shell 21 and covering the opening.

[0250] The electrode assembly 10 is accommodated in the case 20. The electrode assembly 10 includes a positive electrode tab 11 and a negative electrode tab 12. The positive electrode tab 11 includes a positive electrode main body portion 111 provided with a positive electrode active material layer 113 and a plurality of positive electrode tabs 112 extending from the positive electrode main body portion 111 toward the edge of the end cap 22. The negative electrode tab 12 includes a negative electrode main body portion 121 provided with a negative electrode active material layer 123 and a plurality of negative electrode tabs 122 extending from the edge of the negative electrode main body portion 121 toward the end cap 22.

[0251] The positive electrode lead-out portion 30 includes a positive electrode terminal 31 and a positive electrode adapter tab 32. The positive electrode adapter tab 32 is welded to the plurality of positive electrode tabs 112 and forms a first weld mark P1. The positive electrode terminal 31 is provided to the end cap 22 and is welded to the positive electrode adapter tab 32 and forms a third weld mark P3.

[0252] The negative electrode lead-out portion 40 includes a negative electrode terminal 41 and a negative electrode adapter tab 42. The negative electrode adapter tab 42 is welded to the plurality of negative electrode tabs 122 and forms a second weld mark P2. The negative electrode terminal 41 is provided to the end cap 22 and is welded to the negative electrode adapter tab 42 and forms a fourth weld mark P4.

[0253] The positive electrode tab 112 includes a positive electrode connecting portion 1121. One end of the positive electrode connecting portion 1121 is connected to the positive electrode main body portion 111, and the other end is connected to the first weld mark P1. The negative electrode tab 122 includes a negative electrode connecting portion 1221. One end of the negative electrode connecting portion 1221 is connected to the negative electrode main body portion 121, and the other end is connected to the second weld mark P2. The sum of the minimum flow cross-sectional areas of the positive electrode connecting portions 1121 of the plurality of positive electrode tabs 112 is S1. The sum of the minimum flow cross-sectional areas of the negative electrode connecting portions 1221 of the plurality of negative electrode tabs 122 is S2.

[0254] The electrical conductivity of the positive electrode tab 112 is σ c , and the electrical conductivity of the negative electrode tab 122 is σ a . S1 / S2≥σ a / σ c .

[0255] The number of the positive electrode tabs 112 of the electrode assembly 10 is m, and the minimum flow cross-sectional area of the positive electrode connecting portion 1121 is S 11 . S1=m×S 11 The number of the negative electrode tabs 122 of the electrode assembly 10 is n, and the minimum flow cross-sectional area of the negative electrode connecting portion 1221 is S 21 . S2=n×S 21 . m is greater than n.

[0256] The width of the positive electrode connecting portion 1121 is greater than the width of the negative electrode connecting portion 1221. The thickness of the positive electrode connecting portion 1121 is greater than the thickness of the negative electrode connecting portion 1221.

[0257] Although the present application has been described with reference to preferred embodiments, it is to be understood that various modifications can be made without departing from the scope of the application, and that the application is not to be limited to the particulars disclosed herein unless the specification specifically states otherwise. Furthermore, where a term is provided in the description and / or claims that is not specifically recited in the background art, it is to be understood that such term is included in the present application as used herein.

Claims

1. A battery cell, comprising: a housing; a positive lead-out portion and a negative lead-out portion disposed in the housing; an electrode assembly accommodated in the housing, the electrode assembly comprising a positive electrode tab and a negative electrode tab, the positive electrode tab comprising a positive electrode main body portion provided with a positive electrode active material layer and a positive electrode ear extending from an edge of the positive electrode main body portion, the negative electrode tab comprising a negative electrode main body portion provided with a negative electrode active material layer and a negative electrode ear extending from an edge of the negative electrode main body portion, the negative electrode ear having a greater electrical conductivity than the positive electrode ear, a plurality of the positive electrode ears being welded to the positive lead-out portion and forming a first weld, and a plurality of the negative electrode ears being welded to the negative lead-out portion and forming a second weld; wherein the positive electrode ear comprises a positive electrode connecting portion, one end of the positive electrode connecting portion being connected to the positive electrode main body portion and the other end of the positive electrode connecting portion being connected to the first weld; and the negative electrode ear comprises a negative electrode connecting portion, one end of the negative electrode connecting portion being connected to the negative electrode main body portion and the other end of the negative electrode connecting portion being connected to the second weld; wherein a sum of minimum cross-sectional areas of the positive electrode connecting portions of the plurality of the positive electrode ears is S1, a sum of minimum cross-sectional areas of the negative electrode connecting portions of the plurality of the negative electrode ears is S2, and S1 is greater than S2. The total volume of the plurality of the positive electrode connecting portions is greater than or equal to the total volume of the plurality of the negative electrode connecting portions. The minimum width of the positive electrode connecting portion is greater than the minimum width of the negative electrode connecting portion. The thickness of the positive electrode ear is greater than the thickness of the negative electrode ear. The number of the positive electrode ears is greater than the number of the negative electrode ears. The area of the first weld is greater than the area of the second weld.

2. The battery cell of claim 1, wherein, the positive tab has an electrical conductivity σ c , the negative tab has an electrical conductivity σ a ; S1 / S2≥ σ a / σ c .

3. The battery cell of claim 1 or 2, wherein, The positive lead-out portion comprises a positive electrode terminal and a positive electrode adapter tab, the positive electrode adapter tab being welded to the plurality of the positive electrode ears and forming the first weld, the positive electrode terminal being disposed in the housing and being welded to the positive electrode adapter tab and forming a third weld.

4. The battery cell of any one of claims 1-3, wherein, The positive electrode connecting portion has two first surfaces opposite in the thickness direction of the positive electrode connecting portion, and the area of the first surface is S c ; the negative electrode connecting portion has two second surfaces opposite in the thickness direction of the negative electrode connecting portion, and the area of the second surface is S a ; The negative tab has a thermal conductivity greater than the thermal conductivity of the positive tab, and S c greater than S a .

5. The battery cell of any one of claims 1-4, wherein, The negative lead-out portion comprises a negative electrode terminal and a negative electrode adapter tab, the negative electrode adapter tab being welded to the plurality of the negative electrode ears and forming the second weld, the negative electrode terminal being disposed in the housing and being welded to the negative electrode adapter tab and forming a fourth weld.

6. The battery cell of any one of claims 1-5, wherein, The area of the third weld is greater than the area of the fourth weld.

7. The battery cell of any one of claims 1-6, wherein, The minimum flow distance between the first weld and the third weld is less than the minimum flow distance between the second weld and the fourth weld.

8. The battery cell of any one of claims 1-7, wherein, The volume of the positive electrode adapter tab is greater than or equal to the volume of the negative electrode adapter tab.

9. The battery cell of any one of claims 1-8, wherein, The minimum cross-sectional area of the positive electrode terminal is greater than or equal to the minimum cross-sectional area of the negative electrode terminal. The positive electrode ear is made of aluminum and the negative electrode ear is made of copper.

10. The battery cell of claim 9, wherein, The positive electrode tab further comprises a conductive layer coated on the positive electrode connecting portion.

11. The battery cell of claim 9 or 10, wherein, The average charge rate of the battery cell is K, satisfying K≥2.

12. The battery cell of any one of claims 9-11, wherein, 17.A battery device comprising a plurality of battery cells according to any one of claims 1-16.

13. The battery cell of any one of claims 9-12, wherein, 18.The battery device according to claim 17, further comprising a heat exchange member for exchanging heat with the positive lead-out portion.

14. The battery cell of any one of claims 1-13, wherein, ​ 15. The battery cell of any one of claims 1-14, wherein, ​ 16. The battery cell of any one of claims 1-15, wherein, ​ ​ ​ 19. An electrically powered device comprising a battery device according to claim 17 or 18, said battery device being used to provide electrical energy.

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