Battery cell, battery device, and electric device

Abstract

The application discloses a battery monomer, a battery device and an electric equipment. The battery monomer comprises a shell, an electrode assembly and an end cover. The shell has a first accommodating space and a first opening communicating with the first accommodating space. The electrode assembly is arranged in the first accommodating space. The end cover is connected to the shell and seals the first opening. The electrode assembly comprises a positive electrode sheet, a diaphragm and a negative electrode sheet which are stacked and wound. The thickness of the substrate of at least one of the positive electrode sheet and the negative electrode sheet located at the inner circle of the electrode assembly is greater than the thickness located at the outer circle of the electrode assembly. By increasing the cross-sectional area of the substrate of at least one of the positive electrode sheet and the negative electrode sheet located at the inner circle of the electrode assembly, the resistance of the inner circle of the electrode assembly can be reduced, the problem of heat accumulation in the inner circle of the electrode assembly can be improved, the risk of thermal runaway of the battery monomer can be reduced, and the reliability of the battery monomer and the battery device can be improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell, battery device, and electrical equipment. Background Technology

[0002] With the development of battery technology, wound battery devices have emerged in order to improve the energy capacity and charging speed of battery devices.

[0003] The electrode assembly of a wound battery device is formed by winding together a positive electrode, a separator, and a negative electrode. The heat dissipation path of the electrode assembly gradually increases from the outer ring to the inner ring, which makes it easy for heat to accumulate in the inner ring of the electrode assembly, which can easily cause risks such as thermal runaway and affect the reliability of the electrode cells and the battery device. Utility Model Content

[0004] In view of the above problems, this application provides a battery cell, a battery device, and an electrical device to reduce heat accumulation in the inner ring of the electrode assembly, thereby reducing the risk of thermal runaway in the battery cell and improving the reliability of the battery cell and the battery device.

[0005] In a first aspect, this application provides a battery cell, comprising: a housing having a first accommodating space and a first opening communicating with the first accommodating space; an electrode assembly disposed within the first accommodating space; and an end cap connected to the housing and closing the first opening; wherein the electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet stacked and wound together, and the thickness of the substrate of at least one of the positive and negative electrode sheets in the inner ring of the electrode assembly is greater than the thickness in the outer ring of the electrode assembly. By configuring the substrate of at least one of the positive and negative electrode sheets such that the thickness in the inner ring of the electrode assembly is greater than the thickness in the outer ring of the electrode assembly, the cross-sectional area of ​​the substrate of at least one of the positive and negative electrode sheets in the inner ring of the electrode assembly is increased, which can reduce the resistance of the inner ring of the electrode assembly, thereby reducing the heat generation in the inner ring of the electrode assembly, thus improving the problem of heat accumulation in the inner ring of the electrode assembly, reducing the risk of thermal runaway in the battery cell, and thus improving the reliability of the battery cell and the battery device.

[0006] In some embodiments, the thickness of the substrate of one of the positive and negative electrodes in the inner ring is greater than the thickness in the outer ring; the thickness of the substrate of the other of the positive and negative electrodes in the inner ring is equal to the thickness in the outer ring. This design has several advantages. First, it reduces heat generation in the inner ring of the substrate of either the positive or negative electrode, thus mitigating heat buildup in the inner ring of the electrode assembly. It also increases the structural strength of the inner ring portion of the substrate, improving the fatigue resistance of the localized areas of the electrode assembly. Second, the unchanged thickness of the substrate of the other electrode does not affect heat dissipation in the inner ring. Furthermore, reducing the thickness of the substrate of either the positive or negative electrode in the outer ring of the electrode assembly reduces the radial dimension of the outer ring, shortening the heat dissipation path in the inner ring and improving its efficiency. This further mitigates heat buildup in the inner ring. Third, reducing the thickness of the substrate of either the positive or negative electrode in the outer ring of the electrode assembly also reduces the weight of the electrode assembly and decreases its overall radial dimension, resulting in a simultaneous reduction in weight and volume, thereby increasing the energy density of the individual battery cells.

[0007] In some embodiments, one electrode is a positive electrode and the other is a negative electrode. This configuration, on the one hand, not only reduces the heat generation of the positive electrode substrate in the inner ring, improving the problem of heat accumulation in the inner ring of the electrode assembly, but also increases the structural strength of the portion of the positive electrode substrate in the inner ring, enhancing the fatigue resistance of the inner ring of the positive electrode. On the other hand, by reducing the thickness of the positive electrode substrate in the outer ring of the electrode assembly, the radial dimension of the outer ring of the electrode assembly can be reduced, thereby shortening the heat dissipation path of the inner ring of the electrode assembly, helping to improve the heat dissipation efficiency of the inner ring of the electrode assembly, and further improving the problem of heat accumulation in the inner ring of the electrode assembly.

[0008] In some embodiments, one electrode is a negative electrode and the other is a positive electrode. This configuration, on the one hand, not only reduces the heat generation of the negative electrode substrate in the inner ring, improving the problem of heat accumulation in the inner ring of the electrode assembly, but also increases the structural strength of the portion of the negative electrode substrate in the inner ring, enhancing the fatigue resistance of the inner ring of the negative electrode. On the other hand, by reducing the thickness of the negative electrode substrate in the outer ring of the electrode assembly, the radial dimension of the outer ring of the electrode assembly can be reduced, thereby shortening the heat dissipation path of the inner ring of the electrode assembly, further improving the problem of heat accumulation in the inner ring of the electrode assembly.

[0009] In some embodiments, the substrate includes a first base region and a second base region connecting the first base region. The first base region and the second base region are arranged along the length of the substrate, and the first base region is positioned closer to the axis of the electrode assembly than the second base region. The thickness of the first base region is greater than the thickness of the second base region. This arrangement not only reduces the resistance of the inner ring of the electrode assembly, thereby reducing heat generation and mitigating the risk of heat accumulation, but also reduces the weight and volume of the electrode assembly. This allows for increased energy density of the battery cell while minimizing the risk of thermal runaway.

[0010] In some embodiments, the ratio between the length-direction dimension of the first base region and the length-direction dimension of the second base region is 1:0.01 to 1:100. This configuration not only reduces the resistance of the inner ring of the electrode assembly, thereby reducing heat generation in the inner ring and mitigating the risk of heat accumulation, but also reduces the weight and volume of the electrode assembly. This allows for improving the energy density of the battery cell while reducing the risk of thermal runaway.

[0011] In some embodiments, the ratio between the length-direction dimension of the first base region and the length-direction dimension of the second base region is 1:3 to 1:1. This configuration results in a moderate balance between the thin and thick base regions of the substrate, enabling the reduction of the inner resistance of the electrode assembly while simultaneously reducing the weight and volume of the electrode assembly. This not only improves problems such as thermal runaway caused by heat accumulation but also increases the energy density of the battery cell.

[0012] In some embodiments, the thickness of the first base region is greater than or equal to 2 μm; the thickness of the second base region is greater than or equal to 2 μm. This configuration, on the one hand, can improve the structural strength of the substrate, enabling it to withstand the mechanical stress during production processes such as coating, rolling, and winding, thus reducing the probability of problems such as substrate breakage or wrinkling; on the other hand, it can increase the cross-sectional area of ​​the substrate to reduce its resistance, thereby reducing the heat generated during current transmission and thus reducing the risk of thermal runaway in individual battery cells.

[0013] In some embodiments, the substrate includes a copper foil substrate with a thickness of 3 μm to 8 μm. This configuration, on the one hand, makes the weight of the copper foil substrate moderate, which not only enhances the structural strength of the copper foil substrate and reduces the probability of problems such as breakage or wrinkling, but also increases the energy density of the battery cell; on the other hand, it reduces the resistance of the copper foil substrate, thereby reducing the heat generated during current transmission and thus reducing the risk of thermal runaway in the battery cell.

[0014] In some embodiments, the copper foil substrate includes a first base region and a second base region, wherein the difference between the thickness of the first base region and the thickness of the second base region is 1 μm to 2 μm. This configuration, on the one hand, reduces stress concentration between the first and second base regions, thereby reducing or avoiding problems such as breakage or wrinkling between the first and second base regions; on the other hand, when the number of layers in the inner and outer rings of the electrode assembly is the same, it reduces the difference in radial dimension between the inner and outer rings of the electrode assembly, resulting in a more compact electrode assembly structure. This not only improves the energy density of the battery cell but also reduces the stress difference between the inner and outer rings of the electrode assembly, thus improving the stability of the battery cell.

[0015] In some embodiments, the substrate includes an aluminum foil substrate with a thickness of 10 μm to 20 μm. On the one hand, this allows for a larger cross-sectional area of ​​the aluminum foil substrate, reducing the impedance of the electron transport path. This not only improves the conductivity of the aluminum foil substrate but also reduces the heat generated during current transmission, lowering the risk of thermal runaway in individual battery cells. On the other hand, it enhances the structural strength of the aluminum foil substrate, thereby reducing the risk of breakage or wrinkling.

[0016] In some embodiments, the aluminum foil substrate includes a first base region and a second base region; wherein the difference between the thickness of the first base region and the thickness of the second base region is 1 μm to 3 μm. This configuration, on the one hand, reduces stress concentration between the first and second base regions, thereby reducing or avoiding problems such as breakage or wrinkling between the first and second base regions; on the other hand, when the number of layers in the inner and outer rings of the electrode assembly is the same, it reduces the difference between the radial dimensions of the inner and outer rings of the electrode assembly, resulting in a more compact electrode assembly structure. This not only improves the energy density of the battery cell but also reduces the stress difference between the inner and outer rings of the electrode assembly, thus improving the stability of the battery cell.

[0017] In some embodiments, the positive and negative electrode sheets further include a coating layer disposed on the surface of the substrate; wherein the thickness of the coating layer located in the first base region is less than the thickness of the coating layer located in the second base region. This configuration, on the one hand, reduces the risk of breakage or wrinkling in the second base region due to its thinner thickness, thereby improving the reliability of the substrate; on the other hand, it makes the thickness of the positive or negative electrode sheet in the inner ring of the electrode assembly nearly the same as the thickness in the outer ring of the electrode assembly. This reduces the difference in radial dimensions between the inner and outer rings of the electrode assembly when the number of rings in the inner and outer rings is the same, resulting in a more compact electrode assembly structure. This not only improves the energy density of the battery cell but also reduces the stress difference between the inner and outer rings of the electrode assembly, thus improving the stability of the battery cell.

[0018] In some embodiments, the substrate includes multiple base regions arranged sequentially along the length of the substrate; wherein, the thickness of the multiple base regions of the substrate of at least one of the positive and negative electrode plates gradually decreases from a first end to a second end of the substrate along the length direction; the first end is positioned relative to the second end near the axis of the electrode assembly. This arrangement causes the cross-sectional area of ​​the substrate of at least one of the positive and negative electrode plates to gradually increase from the end of the substrate near the axis of the electrode assembly to the end away from the axis of the electrode assembly, so that the resistance of the electrode assembly gradually decreases from the region near the axis of the electrode assembly to the region away from the axis. This results in a gradual decrease in the heat generated by the electrode assembly from the region away from the axis of the electrode assembly to the region near the axis, which can improve the problem of heat accumulation in the inner ring of the electrode assembly, reduce the risk of thermal runaway in the battery cell, and thus improve the reliability of the battery cell and the battery device.

[0019] In some embodiments, the substrate thickness of one of the positive and negative electrode sheets is greater in the inner ring than in the outer ring; the substrate thickness of the other of the positive and negative electrode sheets is less in the inner ring than in the outer ring. This arrangement makes the thicknesses of the positive and negative electrode sheets complementary in the inner and outer rings of the electrode assembly, improving the consistency of gaps and other dimensions between the inner and outer rings. This reduces the difference in radial dimensions between the inner and outer rings when the number of inner and outer rings is the same, resulting in a more compact electrode assembly structure. This not only increases the energy density of the battery cell but also reduces stress differences between the inner and outer rings, improving the stability of the battery cell.

[0020] Secondly, this application provides a battery device, comprising: a battery housing having a second receiving space; and the aforementioned battery cell, the battery cell being disposed within the second receiving space. By configuring the substrate of at least one of the positive and negative electrode plates such that the thickness of the inner ring of the electrode assembly is greater than the thickness of the outer ring of the electrode assembly, the cross-sectional area of ​​the substrate of at least one of the positive and negative electrode plates located in the inner ring of the electrode assembly is increased. This reduces the resistance of the inner ring of the electrode assembly, thereby reducing the heat generation in the inner ring of the electrode assembly. This improves the problem of heat accumulation in the inner ring of the electrode assembly, reduces the risk of thermal runaway in the battery cell, and ultimately improves the reliability of the battery cell and the battery device.

[0021] Thirdly, this application provides an electrical device, which includes the aforementioned battery device. Attached Figure Description

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0023] In the picture:

[0024] Figure 1 This is a schematic diagram of the structure of an embodiment of the electrical equipment provided in this application;

[0025] Figure 2 This is an exploded structural diagram of an embodiment of the battery device provided in this application;

[0026] Figure 3 This is a cross-sectional structural schematic diagram of an embodiment of the battery cell provided in this application;

[0027] Figure 4 This is a schematic diagram of the structure of the substrate of the battery cell provided in this application in the first embodiment;

[0028] Figure 5 This is a schematic diagram of the second embodiment of the substrate of the battery cell provided in this application;

[0029] Figure 6 This is a schematic diagram of the third embodiment of the substrate of the battery cell provided in this application;

[0030] Figure 7 This is a schematic diagram of the fourth embodiment of the substrate of the battery cell provided in this application;

[0031] Figure 8 This is a schematic diagram of the fifth embodiment of the substrate of the battery cell provided in this application.

[0032] The reference numerals in the detailed embodiments are as follows:

[0033] Vehicle 1000a, battery device 100a, controller 200a, motor 300a, battery box 10, second receiving space 10a, second opening 10b, first part 11, second part 12, third part 13, battery cell 20, casing 21, first receiving space 21a, electrode assembly 22, inner ring 22a, outer ring 22b, positive electrode 221, negative electrode 222, separator 223, substrate 23, first base region 231, second base region 232, first end 23a, second end 23b, base region 233, coating layer 24. Detailed Implementation

[0034] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0035] 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 pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0036] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0037] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0038] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0039] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0040] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate heat exchange medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0041] With the development of battery technology, wound battery devices have emerged to improve the energy capacity and charging speed of battery devices. Unlike traditional stacked battery devices, the electrode assembly of a wound battery device is a structure formed by winding together layers of positive electrode plates, negative electrode plates, and separators in thin sheets. This allows for more complete chemical reactions inside the battery device and improves the conductivity between the positive and negative electrode plates, thereby increasing the energy capacity and charging speed of the battery device.

[0042] However, since the electrode assembly of a wound battery device is formed by winding together a stacked positive electrode, a separator, and a negative electrode, the heat dissipation path of the electrode assembly gradually increases from the outer ring to the inner ring. This causes heat to easily accumulate in the inner ring of the electrode assembly, which can easily lead to risks such as thermal runaway and affect the reliability of the electrode cells and the battery device.

[0043] Based on the above considerations, this application provides a battery cell, a battery device, and an electrical appliance. The battery cell includes a housing, an electrode assembly, and an end cap. The housing has a first receiving space and an opening communicating with the first receiving space. The electrode assembly is disposed within the first receiving space. The end cap is connected to the housing and closes the opening. The electrode assembly includes a positive electrode, a separator, and a negative electrode, which are stacked and wound together. The thickness of the substrate of at least one of the positive and negative electrode sheets in the inner ring of the electrode assembly is greater than the thickness in the outer ring. By configuring the substrate of at least one of the positive and negative electrode sheets such that the thickness in the inner ring of the electrode assembly is greater than the thickness in the outer ring, the cross-sectional area of ​​the substrate of at least one of the positive and negative electrode sheets in the inner ring of the electrode assembly is increased. This reduces the resistance of the inner ring of the electrode assembly, thereby reducing heat generation in the inner ring and improving the problem of heat accumulation in the inner ring of the electrode assembly. This reduces the risk of thermal runaway in the battery cell, thereby improving the reliability of the battery cell and the battery device.

[0044] The battery cell, battery device, and electrical equipment disclosed in this application can be used in electrical equipment that uses the battery device as a power source or in various energy storage systems that use the battery device as an energy storage element. The electrical equipment can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0045] For ease of explanation, the following embodiments will be described using a vehicle 1000a as an example of an electrical device according to an embodiment of this application.

[0046] Please refer to Figure 1 The vehicle 1000a can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A battery device 100a is installed inside the vehicle 1000a, and the battery device 100a can be located at the bottom of the vehicle 1000a. The battery device 100a can be used to power the vehicle 1000a; for example, the battery device 100a can serve as the operating power source for the vehicle 1000a. The vehicle 1000a may also include a controller 200a and a motor 300a. The controller 200a is used to control the battery device 100a to supply power to the motor 300a, for example, to meet the power needs of the vehicle 1000a during starting, navigation, and driving.

[0047] In some embodiments of this application, the battery device 100a can not only serve as the operating power source for the vehicle 1000a, but also as the driving power source for the vehicle 1000a, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000a.

[0048] In some embodiments, the battery device 100a may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0049] Please refer to Figure 2 The battery device 100a mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include a plurality of battery cells 20, which are connected in series, parallel, or mixed connection via a busbar.

[0050] In this embodiment of the application, the battery cell 20 can be a secondary battery, which refers to a battery cell 20 that can be used again after being discharged by recharging to activate the active materials.

[0051] The battery cell 20 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0052] In some embodiments, the battery housing 10 may be part of the chassis structure of the vehicle 1000a. For example, a portion of the battery housing 10 may be at least a portion of the floor of the vehicle 1000a, or a portion of the battery housing 10 may be at least a portion of the crossbeams and longitudinal beams of the vehicle 1000a.

[0053] Please continue to refer to Figure 2The battery device 100a includes a battery housing 10 and a battery cell 20. The battery cell 20 is housed within the battery housing 10. The battery housing 10 forms a second receiving space 10a, within which the battery cell 20 is disposed. The battery housing 10 can have various structures. In some embodiments, the battery housing 10 may include a first portion 11, a second portion 12, and a third portion 13. The first portion 11 may be a hollow structure with second openings 10b at both ends, the second portion 12 may be a hollow structure with a second opening 10b at one end, and the third portion 13 may also be a hollow structure with a second opening 10b at one end. The first portion 11, the second portion 12, and the third portion 13 overlap each other, collectively defining the second receiving space 10a for accommodating the battery cell 20. In some embodiments, the first portion 11 forms a second receiving space 10a. The first portion 11 can be a hollow structure with second openings 10b at both ends. The second portion 12 and the third portion 13 are both plate-like structures. The second portion 12 covers one second opening 10b of the first portion 11, and the third portion 13 covers the other second opening 10b of the first portion 11 to close the second receiving space 10a. In some embodiments, the battery housing 10 includes only the first portion 11 and the second portion 12. The first portion 11 can be a hollow structure with a second opening 10b at one end, and the second portion 12 can be a plate-like structure. The second portion 12 covers the second opening 10b of the first portion 11 so that the first portion 11 and the second portion 12 together define the second receiving space 10a. Alternatively, the first portion 11 and the second portion 12 can both be hollow structures with a second opening 10b on one side, and the second opening 10b of the first portion 11 and the second opening 10b of the second portion 12 are connected. The battery housing 10 can have various shapes, such as cylindrical, cuboid, or cube, but is not limited to these.

[0054] In some embodiments, please refer to Figures 3 to 6 The battery cell 20 includes a housing 21, an electrode assembly 22, and an end cap (not shown). The housing 21 has a first receiving space 21a and a first opening (not shown) communicating with the first receiving space 21a. The electrode assembly 22 is disposed within the first receiving space 21a. The end cap is connected to the housing 21 and closes the first opening. The electrode assembly 22 includes a positive electrode 221, a separator 223, and a negative electrode 222 stacked and wound together. The thickness of the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 in the inner ring 22a of the electrode assembly 22 is greater than the thickness in the outer ring 22b of the electrode assembly 22.

[0055] The battery cell 20 includes one or more electrode assemblies 22, a housing 21, and an end cap. The housing 21 has a first receiving space 21a and a first opening communicating with the first receiving space 21a, the first receiving space 21a being used to receive the electrode assembly 22. The end cap is connected to the housing 21 and closes the first opening. The housing 21 is a component used to receive the electrode assembly 22. The housing 21 can be a hollow structure with a first opening at one end, or a hollow structure with first openings at both opposite ends. The housing 21 can have various shapes, such as cylindrical, cuboid, or cubic, but is not limited to these. The material of the housing 21 can be copper, iron, aluminum, steel, or aluminum alloy, but is not limited to these.

[0056] The end cap is a component that closes the first opening of the housing 21 to isolate the internal environment of the battery cell 20 from the external environment. The end cap and housing 21 together define a first receiving space 21a for accommodating the electrode assembly 22, electrolyte, and other components. The end cap can be connected to the housing 21 by welding or roll sealing to close the first opening of the housing 21. The shape of the end cap can be adapted to the shape of the housing 21. For example, if the housing 21 is a cuboid structure, the end cap is a rectangular plate structure adapted to the housing 21; similarly, if the housing 21 is a cylindrical structure, the end cap is a circular plate structure adapted to the housing 21. The end cap can be made of copper, iron, aluminum, steel, aluminum alloy, or plastic, but is not limited to these materials. The end cap and housing 21 can be made of the same material, or they can be different materials.

[0057] The electrode assembly 22 includes two separators 223. The electrode assembly 22 can be formed by sequentially stacking and winding one separator 223, a positive electrode 221, another separator 223, and a negative electrode 222; alternatively, the electrode assembly 22 can also be formed by sequentially stacking and winding one separator 223, a negative electrode 222, another separator 223, and a positive electrode 221. The two separators 223 together isolate the positive electrode 221 and the negative electrode 222, preventing them from contacting each other, thereby reducing or eliminating the risk of short circuits caused by contact between the positive and negative electrodes 221 and 222.

[0058] Please refer to the following: Figure 7Both the positive electrode 221 and the negative electrode 222 include a substrate 23 and a coating layer 24. The coating layer 24 is disposed on two opposing surfaces of the substrate 23 along its thickness direction, wherein the thickness direction is parallel to the radial direction of the electrode assembly 22. The substrate 23 of the positive electrode 221 is also the current collector of the positive electrode 221, and the substrate 23 of the negative electrode 222 is also the current collector of the negative electrode 222. The coating layer 24 is also the electrode active material layer. The substrate 23 of the positive electrode 221 can be an aluminum foil substrate, a copper foil substrate, a titanium foil substrate, or a stainless steel foil substrate, but is not limited to these. The substrate 23 of the negative electrode 222 can be a copper foil substrate, an aluminum foil substrate, a stainless steel foil substrate, or a nickel foil substrate, etc., but is not limited to these. The material of the substrate 23 of the positive electrode 221 and the negative electrode 222 can be selected according to the specific situation. For example, in a lithium-ion battery, the substrate 23 of the positive electrode 221 can be an aluminum foil substrate, and the substrate 23 of the negative electrode 222 can be a copper foil substrate.

[0059] The electrode assembly 22 includes an inner ring 22a and an outer ring 22b arranged radially, wherein the inner ring 22a is positioned relative to the outer ring 22b close to the axis of the electrode assembly 22.

[0060] The thickness distribution of the substrate 23 of the positive electrode 221 and the negative electrode 222 can have at least the following conditions: For example, the thickness of the substrate 23 of the positive electrode 221 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness located in the outer ring 22b of the electrode assembly 22, and the thickness of the substrate 23 of the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is equal to the thickness located in the outer ring 22b of the electrode assembly 22. Another example is that the thickness of the substrate 23 of the positive electrode 221 located in the inner ring 22a of the electrode assembly 22 is equal to the thickness located in the outer ring 22b of the electrode assembly 22, and the thickness of the substrate 23 of the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness located in the outer ring 22b of the electrode assembly 22. Yet another example is that the thickness of the substrate 23 of both the positive electrode 221 and the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness located in the outer ring 22b of the electrode assembly 22. The thickness of the substrate 23 is also the radial dimension of the substrate 23 along the electrode assembly 22.

[0061] By configuring the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 such that the thickness of the inner ring 22a of the electrode assembly 22 is greater than the thickness of the outer ring 22b of the electrode assembly 22, the cross-sectional area of ​​at least a portion of the substrate 23 of the positive electrode 221 and the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is increased. This reduces the resistance of the inner ring 22a of the electrode assembly 22, thereby reducing the heat generation in the inner ring 22a of the electrode assembly 22. This improves the problem of heat accumulation in the inner ring 22a of the electrode assembly 22, reduces the risk of thermal runaway in the battery cell 20, and improves the reliability of the battery cell 20 and the battery device 100a.

[0062] In some embodiments, please continue to refer to Figures 4 to 5 The thickness of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 in the inner ring 22a of the electrode assembly 22 is greater than the thickness in the outer ring 22b of the electrode assembly 22; the thickness of the substrate 23 of the other of the positive electrode 221 and the negative electrode 222 in the inner ring 22a of the electrode assembly 22 is equal to the thickness in the outer ring 22b of the electrode assembly 22.

[0063] If the thickness of the substrate 23 of the positive electrode 221 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22, then the thickness of the substrate 23 of the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is equal to the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22.

[0064] By making the thickness of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 in the inner ring 22a of the electrode assembly 22 greater than that in the outer ring 22b of the electrode assembly 22, and making the thickness of the substrate 23 of the other electrode 222 in the inner ring 22a equal to that in the outer ring 22b of the electrode assembly 22, on the one hand, not only can the heat generation of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 in the inner ring 22a be reduced, thereby improving the problem of heat accumulation in the inner ring 22a of the electrode assembly 22, but also the structural strength of the portion of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 in the inner ring 22a can be improved, thereby improving the fatigue resistance of the local area of ​​the electrode assembly 22; on the other hand, since the thickness of the substrate 23 of the other electrode 221 and the negative electrode 222 remains unchanged, it will not affect The heat dissipation effect of the inner ring 22a is improved. Furthermore, by reducing the thickness of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 in the outer ring 22b of the electrode assembly 22, the radial dimension of the outer ring 22b of the electrode assembly 22 can be reduced, thereby shortening the heat dissipation path of the inner ring 22a of the electrode assembly 22. This helps to improve the heat dissipation efficiency of the inner ring 22a of the electrode assembly 22, and further improves the problem of heat accumulation in the inner ring 22a of the electrode assembly 22. Thirdly, by reducing the thickness of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 in the outer ring 22b of the electrode assembly 22, the weight of the electrode assembly 22 can also be reduced, and the overall radial dimension of the electrode assembly 22 can be reduced, so that the weight and volume of the electrode assembly 22 can be reduced simultaneously, thereby increasing the energy density of the battery cell 20.

[0065] In some embodiments, please continue to refer to Figure 4 One of the positive electrode plate 221 and the negative electrode plate 222 is the positive electrode plate 221, and the other of the positive electrode plate 221 and the negative electrode plate 222 is the negative electrode plate 222.

[0066] In this case, the thickness of the substrate 23 of the positive electrode 221 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22, and the thickness of the substrate 23 of the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is equal to the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22. With this structure, on the one hand, it can not only reduce the heat generation of the substrate 23 of the positive electrode 221 located in the inner ring 22a and improve the problem of heat accumulation in the inner ring 22a of the electrode assembly 22, but also improve the structural strength of the portion of the substrate 23 of the positive electrode 221 located in the inner ring 22a, thereby improving the fatigue resistance of the inner ring 22a of the positive electrode 221. On the other hand, by reducing the thickness of the substrate 23 of the positive electrode 221 located in the outer ring 22b of the electrode assembly 22, the radial dimension of the outer ring 22b of the electrode assembly 22 can be reduced, thereby shortening the heat dissipation path of the inner ring 22a of the electrode assembly 22, which helps to improve the heat dissipation efficiency of the inner ring 22a of the electrode assembly 22, and further improve the problem of heat accumulation in the inner ring 22a of the electrode assembly 22.

[0067] In some embodiments, please continue to refer to Figure 5 One of the positive electrode 221 and the negative electrode 222 is the negative electrode 222, and the other of the positive electrode 221 and the negative electrode 222 is the positive electrode 221.

[0068] In this case, the thickness of the substrate 23 of the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22, and the thickness of the substrate 23 of the positive electrode 221 located in the inner ring 22a of the electrode assembly 22 is equal to the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22. With this structure, on the one hand, it can not only reduce the heat generation of the substrate 23 of the negative electrode 222 located in the inner ring 22a and improve the problem of heat accumulation in the inner ring 22a of the electrode assembly 22, but also improve the structural strength of the portion of the substrate 23 of the negative electrode 222 located in the inner ring 22a and improve the fatigue resistance of the inner ring 22a of the negative electrode 222. On the other hand, by reducing the thickness of the substrate 23 of the negative electrode 222 located in the outer ring 22b of the electrode assembly 22, the radial dimension of the outer ring 22b of the electrode assembly 22 can be reduced, thereby shortening the heat dissipation path of the inner ring 22a of the electrode assembly 22, and further improving the problem of heat accumulation in the inner ring 22a of the electrode assembly 22.

[0069] Furthermore, since the thickness of the substrate 23 of the negative electrode 222 located in the outer ring 22b of the electrode assembly 22 is thinner than that located in the inner ring 22a, the thickness of the coating layer 24 on the portion of the substrate 23 of the negative electrode 222 located in the outer ring 22b can be greater than the thickness of the coating layer 24 on the portion of the substrate 23 of the negative electrode 222 located in the inner ring 22a. On the one hand, by increasing the thickness of the coating layer 24 on the portion of the substrate 23 of the negative electrode 222 located in the outer ring 22b, the capacity of the negative electrode 222 can be increased, allowing the negative electrode 222 to have sufficient space to embed lithium ions, thereby reducing the risk of lithium plating. On the other hand, by making the thickness of the negative electrode 222 located in the inner ring 22a and the thickness located in the outer ring 22b approximately the same, the difference between the radial dimensions of the inner ring and the radial dimensions of the outer ring of the electrode assembly can be reduced, making the structure of the electrode assembly more compact and improving the stability of the electrode assembly 22.

[0070] In some embodiments, please continue to refer to Figure 6 In this structure, the thickness of the substrate 23 of both the positive electrode 221 and the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22. This structure increases the cross-sectional area of ​​the substrate 23 of both the positive electrode 221 and the negative electrode 222 within the inner ring 22a of the electrode assembly 22, reducing the resistance of the inner ring 22a and thus reducing heat generation. This improves the problem of heat accumulation in the inner ring 22a of the electrode assembly 22, reduces the risk of thermal runaway in the battery cell 20, and ultimately improves the reliability of the battery cell 20 and the battery device 100a. Furthermore, it reduces the thickness of the outer ring 22b of the electrode assembly 22. The radial dimension of 22b along the electrode assembly 22 can shorten the heat dissipation path of the inner ring 22a of the electrode assembly 22, thereby further improving the problem of heat accumulation in the inner ring 22a of the electrode assembly 22; thirdly, by reducing the thickness of the substrate 23 of the positive electrode 221 and the negative electrode 222 located in the outer ring 22b of the electrode assembly 22, the weight of the electrode assembly 22 can also be reduced, and the overall radial dimension of the electrode assembly 22 can be reduced, so that the weight and volume of the electrode assembly 22 can be reduced simultaneously, thereby improving the energy density of the battery cell 20.

[0071] In some embodiments, please continue to refer to Figures 4 to 6 The substrate 23 includes a first base region 231 and a second base region 232 connected to the first base region 231. The first base region 231 and the second base region 232 are arranged along the length direction of the substrate 23, and the first base region 231 is positioned relative to the second base region 232 closer to the axis of the electrode assembly 22. The thickness of the first base region 231 is greater than the thickness of the second base region 232.

[0072] The electrode assembly 22 is formed by winding a positive electrode 221, a separator 223, and a negative electrode 222 along the winding direction XX, which is also the length direction of the substrate 23. In the electrode assembly 22, the length direction of the substrate 23 is helical, and the width direction of the substrate 23 is parallel to the axis of the electrode assembly 22.

[0073] If the substrate 23 has two regions with different thicknesses along its length, the thicker region of the substrate 23 is designated as the first base region 231, and the thinner region relative to the first base region 231 is designated as the second base region 232. The first base region 231 is positioned closer to the axis of the electrode assembly 22 relative to the second base region 232. For example, if the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 includes the first base region 231 and the second base region 232, before the electrode assembly 22 is wound, the first base region 231 is located at the beginning of the winding direction XX, and the second base region 232 is located at the end of the winding direction. This ensures that after the electrode assembly 22 is wound, the first base region 231 is positioned closer to the axis of the electrode assembly 22 relative to the second base region 232. Consequently, the thickness of the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness located in the outer ring 22b of the electrode assembly 22.

[0074] By configuring the substrate 23 to include a first base region 231 and a second base region 232, wherein the thickness of the first base region 231 is greater than the thickness of the second base region 232, and the first base region 231 is positioned closer to the axis of the electrode assembly 22 relative to the second base region 232, it is possible not only to reduce the resistance of the inner ring 22a of the electrode assembly 22, thereby reducing the heat generation of the inner ring 22a and reducing the risk of heat accumulation, but also to reduce the weight and volume of the electrode assembly 22, thereby achieving the goal of increasing the energy density of the battery cell 20 while reducing the risk of thermal runaway.

[0075] If the thickness of substrate 23 is constant along the length direction, then substrate 23 does not have a first base region 231 and a second base region 232.

[0076] In some embodiments, the ratio between the length-direction dimension of the first base region 231 and the length-direction dimension of the second base region 232 is 1:0.01 to 1:100.

[0077] The ratio between the length-direction dimension of the first base region 231 and the length-direction dimension of the second base region 232 is 1:0.01, 1:0.1, 1:0.3, 1:0.5, 1:0.6, 1:0.68, 1:0.7, 1:0.8, 1:0.88, 1:0.95, 1:1, 1:1.15, 1:1.18, 1:2, 1:25, 1:3, 1:5, 1:8, 1:10, 1:15, 1:20, 1:26, and 1:30. 1:40, 1:45, 1:48, 1:50, 1:56, 1:58, 1:60, 1:66.8, 1:68.6, 1:70, 1:75, 1:80, 1:86, 1:88, 1:90, 1:95, 1:100, etc., but not limited to these. They can be selected according to actual needs, as long as the ratio between the length direction dimension of the first base region 231 and the length direction dimension of the second base region 232 is within the range of 1:0.01 to 1:100.

[0078] By adjusting the ratio between the length-direction dimension of the first base region 231 and the length-direction dimension of the second base region 232, it is possible to achieve the following: the first base region 231 is entirely located within the inner ring 22a of the electrode assembly 22, and the second base region 232 is entirely located within the outer ring 22b of the electrode assembly 22; or, a portion of the first base region 231 is located within the inner ring 22a of the electrode assembly 22, and another portion extends to the outer ring 22b of the electrode assembly 22, with the second base region 232 located within the outer ring 22b of the electrode assembly 22; or, a portion of the second base region 232 is located within the outer ring 22b of the electrode assembly 22, and another portion extends to the inner ring 22a of the electrode assembly 22, with the first base region 231 located within the outer ring 22b of the electrode assembly 22. The distribution of the first base region 231 and the second base region 232 can be achieved by changing the ratio between the length-direction dimension of the first base region 231 and the length-direction dimension of the second base region 232, etc.

[0079] By making the ratio between the length-direction dimension of the first base region 231 and the length-direction dimension of the second base region 232 within the range of 1:0.01 to 1:100, it is possible not only to reduce the resistance of the inner ring 22a of the electrode assembly 22, thereby reducing the heat generation of the inner ring 22a and reducing the risk of heat accumulation, but also to reduce the weight and volume of the electrode assembly 22, thereby achieving the goal of increasing the energy density of the battery cell 20 while reducing the risk of thermal runaway.

[0080] In some embodiments, the ratio between the length-direction dimension of the first base region 231 and the length-direction dimension of the second base region 232 is 1:3 to 1:1.

[0081] The ratios between the length-direction dimensions of the first base region 231 and the length-direction dimensions of the second base region 232 are 1:3, 1:2.295, 1:2.29, 1:2.285, 1:2.28, 1:2.27, 1:2.266, 1:2.26, 1:2.258, 1:2.25, 1:2.245, 1:2.23, 1:2.22, 1:2.15, 1:2, 1:1.9, 1:1.88, and 1:1.85. The ratios can be 1:1.776, 1:1.6, 1:1.56, 1:1.53, 1:1.5, 1:1.45, 1:1.4, 1:1.33, 1:1.3, 1:1.25, 1:1.22, 1:1.2, 1:1.15, 1:1, etc., but are not limited to these. They can be selected according to actual needs, as long as the ratio between the length dimension of the first base region 231 and the length dimension of the second base region 232 is in the range of 1:3 to 1:1.

[0082] By making the ratio between the length-direction dimension of the first base region 231 and the length-direction dimension of the second base region 232 within the range of 1:3 to 1:1, the thin base region 233 and the thick base region 233 of the substrate 23 are appropriately balanced. This allows for the reduction of the resistance of the inner ring 22a of the electrode assembly 22 while simultaneously reducing the weight and volume of the electrode assembly 22. Consequently, this not only improves problems such as thermal runaway caused by heat accumulation but also increases the energy density of the battery cell 20.

[0083] In some embodiments, the thickness of the first base region 231 is greater than or equal to 2 μm; the thickness of the second base region 232 is greater than or equal to 2 μm.

[0084] The thickness of the first base region 231 can be 2μm, 2.2μm, 2.5μm, 2.8μm, 3μm, 3.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.8μm, 8μm, 8.5μm, 9μm, 10μm, 12μm, 12.5μm, 15μm, 16μm, 18.5μm, 19μm, 20μm, 22μm, 25μm, 26.5μm, 28μm, 30μm, etc., but is not limited to these. It can be selected according to actual needs, as long as the thickness of the first base region 231 is greater than or equal to 2μm.

[0085] The thickness of the second base region 232 can be 2μm, 2.15μm, 2.22μm, 2.5μm, 2.6μm, 2.8μm, 3μm, 3.5μm, 3.8μm, 4.2μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.8μm, 8μm, 8.5μm, 9μm, 10μm, 12μm, 12.5μm, 15μm, 16μm, 18.5μm, 19μm, 20μm, 22μm, 25μm, 26.5μm, 28μm, 30μm, etc., but is not limited to these. It can be selected according to actual needs, as long as the thickness of the second base region 232 is greater than or equal to 2μm.

[0086] If the thickness of the first base region 231 and the second base region 232 is less than 2μm, it not only results in low structural strength of the substrate 23, which is insufficient to withstand the mechanical stress during the coating, rolling, and winding processes, making it prone to breakage or wrinkling, but also increases the resistance of the substrate 23, leading to excessive heat generation and a risk of thermal runaway due to heat concentration. By making the thickness of the first base region 231 greater than or equal to 2μm and the thickness of the second base region 232 greater than or equal to 2μm, on the one hand, the structural strength of the substrate 23 can be improved, enabling it to withstand the mechanical stress during the coating, rolling, and winding processes, reducing the probability of breakage or wrinkling; on the other hand, the resistance of the substrate 23 can be reduced, thereby reducing the heat generated during current transmission and thus reducing the risk of thermal runaway in the battery cell 20.

[0087] In battery systems such as lithium-ion batteries, sodium-ion batteries, and lithium metal batteries, a copper foil substrate can be used as the current collector for the negative electrode 222, and an aluminum foil substrate can be used as the current collector for the positive electrode 221. Similarly, in battery systems such as sodium-ion batteries, aluminum-ion batteries, and magnesium-ion batteries, a copper foil substrate can be used as the current collector for the positive electrode 221, and an aluminum foil substrate can be used as the current collector for the negative electrode 222. In the embodiments described below, the copper foil substrate can be used as the current collector for either the positive or negative electrode 222; the aluminum foil substrate can also be used as the current collector for either the positive or negative electrode 222, and the choice can be made according to actual needs.

[0088] In some embodiments, the substrate 23 includes a copper foil substrate with a thickness of 3 μm to 8 μm.

[0089] The thickness of the copper foil substrate can be 3μm, 3.2μm, 3.35μm, 3.5μm, 3.8μm, 4μm, 4.3μm, 4.5μm, 4.8μm, 5μm, 5.35μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.25μm, 7.66μm, 8μm, etc., but is not limited to these. It can be selected according to actual needs, as long as the thickness of the copper foil substrate is within the range of 3μm to 8μm.

[0090] By making the thickness of the copper foil substrate within the range of 3μm to 8μm, on the one hand, the weight of the copper foil substrate is moderate, which not only enhances the structural strength of the copper foil substrate and reduces the probability of problems such as breakage or wrinkling of the copper foil substrate, but also increases the energy density of the battery cell 20; on the other hand, it can reduce the resistance of the copper foil substrate, thereby reducing the heat generated during current transmission, and thus reducing the risk of thermal runaway of the battery cell 20.

[0091] In some embodiments, the copper foil substrate includes a first base region 231 and a second base region 232, wherein the difference between the thickness of the first base region 231 and the thickness of the second base region 232 is 1 μm to 2 μm.

[0092] The difference between the thickness of the first base region 231 and the thickness of the second base region 232 of the copper foil substrate can be 1.01μm, 1.025μm, 1.085μm, 1.1μm, 1.125μm, 1.15μm, 1.188μm, 1.2μm, 1.25μm, 1.268μm, 1.28μm, 1.3μm, 1.358μm, 1.569μm, 1.6μm, or 1.66μm. The thicknesses can be 1.68μm, 1.7μm, 1.75μm, 1.778μm, 1.8μm, 1.82μm, 1.85μm, 1.88μm, 1.9μm, 1.935μm, 1.988μm, 2μm, etc., but are not limited to these. They can be selected according to actual needs, as long as the difference between the thickness of the first base region 231 and the thickness of the second base region 232 of the copper foil substrate is within the range of 1μm to 2μm.

[0093] If the thicknesses of the first base region 231 and the second base region 232 of the copper foil substrate are different, stress concentration is likely to occur between the first base region 231 and the second base region 232, which may lead to problems such as breakage or wrinkles between the first base region 231 and the second base region 232. By keeping the difference between the thickness of the first base region 231 and the thickness of the second base region 232 of the copper foil substrate within the range of 1μm to 2μm, on the one hand, stress concentration between the first base region 231 and the second base region 232 can be reduced, thereby reducing or avoiding problems such as breakage or wrinkling between the first base region 231 and the second base region 232; on the other hand, when the number of layers of the inner ring 22a and the outer ring 22b of the electrode assembly 22 is the same, the difference between the radial dimensions of the inner ring 22a and the outer ring 22b of the electrode assembly 22 can be reduced, thereby making the structure of the electrode assembly 22 more compact. This not only improves the energy density of the battery cell 20, but also reduces the stress difference between the inner ring 22a and the outer ring 22b of the electrode assembly 22, thus improving the stability of the battery cell 20.

[0094] In some embodiments, the substrate 23 includes an aluminum foil substrate with a thickness of 10 μm to 20 μm.

[0095] The thickness of the aluminum foil substrate can be 10μm, 10.2μm, 10.35μm, 10.5μm, 10.8μm, 11μm, 11.3μm, 11.5μm, 11.8μm, 12μm, 12.35μm, 12.5μm, 13μm, 13.5μm, 13.88μm, 14μm, 14.25μm, 14.66μm, 15μm, or 15.66μm. The thicknesses are 15.9μm, 16μm, 16.5μm, 16.8μm, 17μm, 17.3μm, 17.5μm, 17.77μm, 18μm, 18.35μm, 18.66μm, 19μm, 19.5μm, 19.88μm, 20μm, etc., but are not limited to these. The appropriate thickness can be selected according to actual needs, as long as the thickness of the aluminum foil substrate is within the range of 10μm to 20μm.

[0096] Because aluminum foil substrates have lower density and lower conductivity than copper foil substrates, by making the thickness of the aluminum foil substrate greater than that of the copper foil substrate, that is, by making the thickness of the aluminum foil substrate within the range of 10μm to 20μm, on the one hand, the cross-sectional area of ​​the aluminum foil substrate is larger, which can reduce the impedance of the electron transport path. This not only improves the conductivity of the aluminum foil substrate, but also reduces the heat generated during current transmission, thereby reducing the risk of thermal runaway of the battery cell 20. On the other hand, it can enhance the structural strength of the aluminum foil substrate, thereby reducing the risk of breakage or wrinkling of the aluminum foil substrate.

[0097] In some embodiments, the aluminum foil substrate includes a first base region 231 and a second base region 232; wherein the difference between the thickness of the first base region 231 and the thickness of the second base region 232 is 1 μm to 3 μm.

[0098] The difference between the thickness of the first base region 231 and the thickness of the second base region 232 of the aluminum foil substrate can be 1.01μm, 1.025μm, 1.085μm, 1.1μm, 1.125μm, 1.15μm, 1.188μm, 1.2μm, 1.25μm, 1.268μm, 1.28μm, 1.3μm, 1.358μm, 1.569μm, 1.6μm, 1.66μm, 1.68μm, 1.7μm, 1.75μm, 1.778μm, 1.8μm, 1.82μm, 1.85μm, 1.88μm, 1.9μm, 1.935μm, etc. The thicknesses are 1.988μm, 2μm, 2.025μm, 2.055μm, 2.095μm, 2.11μm, 2.125μm, 2.35μm, 2.388μm, 2.4μm, 2.45μm, 2.478μm, 2.5μm, 2.58μm, 2.6μm, 2.66μm, 2.7μm, 2.75μm, 2.8μm, 2.85μm, 2.9μm, 3μm, etc., but are not limited to these. They can be selected according to actual needs, as long as the difference between the thickness of the first base region 231 and the thickness of the second base region 232 of the aluminum foil substrate is within the range of 1μm to 3μm.

[0099] By keeping the difference between the thickness of the first base region 231 and the thickness of the second base region 232 of the aluminum foil substrate within the range of 1μm to 3μm, on the one hand, stress concentration between the first base region 231 and the second base region 232 can be reduced, thereby reducing or avoiding problems such as breakage or wrinkling between the first base region 231 and the second base region 232; on the other hand, when the number of layers of the inner ring 22a and the outer ring 22b of the electrode assembly 22 is the same, the difference between the radial dimension of the inner ring 22a and the radial dimension of the outer ring 22b of the electrode assembly 22 can be reduced, thereby making the structure of the electrode assembly 22 more compact. This not only improves the energy density of the battery cell 20, but also reduces the stress difference between the inner ring 22a and the outer ring 22b of the electrode assembly 22, thus improving the stability of the battery cell 20.

[0100] In some embodiments, please continue to refer to Figure 7 The positive electrode 221 and the negative electrode 222 also include a coating layer 24 disposed on the surface of the substrate 23. The thickness of the coating layer 24 located in the first base region 231 is less than the thickness of the coating layer 24 located in the second base region 232.

[0101] The coating layer 24 is disposed on two opposing surfaces of the substrate 23 along the thickness direction.

[0102] The coating layer 24 is an electrode active material layer. The coating layer 24 applied to the surface of the substrate 23 of the positive electrode 221 can be lithium cobalt oxide (LiCoO2), lithium iron phosphate (LiFePO4), or a ternary material (NMC / NCA), but is not limited to these. The coating layer 24 applied to the surface of the substrate 23 of the negative electrode 222 can be graphite, silicon-based materials, or lithium metal, but is not limited to these.

[0103] Since the thickness of the first base region 231 is greater than the thickness of the second base region 232, by making the thickness of the coating layer 24 located in the first base region 231 less than the thickness of the coating layer 24 located in the second base region 232, on the one hand, the risk of breakage or wrinkling due to the thinner thickness of the second base region 232 can be reduced, thereby improving the reliability of the substrate 23; on the other hand, by making the thickness of the positive electrode 221 or negative electrode 222 in the inner ring 22a of the electrode assembly 22 nearly the same as the thickness in the outer ring 22b of the electrode assembly 22, the difference between the radial dimensions of the inner ring 22a and the outer ring 22b of the electrode assembly 22 can be reduced when the number of rings in the inner ring 22a and the outer ring 22b of the electrode assembly 22 is the same, thereby making the structure of the electrode assembly 22 more compact. This not only improves the energy density of the battery cell 20, but also reduces the stress difference between the inner ring 22a and the outer ring 22b of the electrode assembly 22, thereby improving the stability of the battery cell 20.

[0104] In some embodiments, the positive electrode 221 includes an aluminum foil substrate, and the negative electrode 222 includes a copper foil substrate. The thickness of the aluminum foil substrate in the inner ring 22a of the electrode assembly 22 is equal to the thickness in the outer ring 22b of the electrode assembly 22. The thickness of the copper foil substrate in the inner ring 22a of the electrode assembly 22 is greater than the thickness in the outer ring 22b of the electrode assembly 22. The thickness of the coating layer 24 disposed on the aluminum foil substrate is less than the thickness of the coating layer 24 disposed on the copper foil substrate. The copper foil substrate includes a first base region 231 and a second base region 232. The thickness of the coating layer 24 disposed on the first base region 231 is less than the thickness of the coating layer 24 disposed on the second base region 232. This configuration serves two purposes. First, it makes the thickness of the negative electrode 222 in the inner ring 22a nearly the same as the thickness in the outer ring 22b, thereby reducing the difference between the radial dimensions of the inner and outer rings of the electrode assembly. This makes the electrode assembly structure more compact and improves the stability of the electrode assembly 22. Second, it makes the capacity of the negative electrode 222 larger than that of the positive electrode 221, giving the negative electrode 222 sufficient space to embed lithium ions, thus reducing the risk of lithium plating.

[0105] In some embodiments, please refer to Figure 8 The substrate 23 includes a plurality of base regions 233, which are arranged sequentially along the length of the substrate 23. The thickness of the plurality of base regions 233 of the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 gradually decreases along the length of the substrate 23 from the first end 23a to the second end 23b of the substrate 23. The first end 23a is positioned close to the axis of the electrode assembly 22 relative to the second end 23b.

[0106] The number of base regions 233 of the substrate 23 can be 2, 3, 5, 6, 8, 10, 11, 12, 15, 18, 20, etc., but is not limited to these, and can be selected according to the actual situation.

[0107] The thickness distribution of the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 has at least the following possible configurations: For example, the thickness of the plurality of base regions 233 of the substrate 23 of the positive electrode 221 gradually decreases along the length direction of the substrate 23 from the first end 23a to the second end 23b of the substrate 23, while the thickness of the substrate 23 of the negative electrode 222 remains unchanged along the length direction. Another example is that the thickness of the plurality of base regions 233 of the substrate 23 of the negative electrode 222 gradually decreases along the length direction of the substrate 23 from the first end 23a to the second end 23b of the substrate 23, while the thickness of the substrate 23 of the positive electrode 221 remains unchanged along the length direction.

[0108] By gradually decreasing the thickness of multiple base regions 233 of the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 along the length direction of the substrate 23 from the first end 23a to the second end 23b of the substrate 23, the cross-sectional area of ​​the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 gradually increases from the end of the substrate 23 near the axis of the electrode assembly 22 to the end away from the axis of the electrode assembly 22. This causes the resistance of the electrode assembly 22 to gradually decrease along the region near the axis of the electrode assembly 22 to the region away from the axis, thereby causing the heat generated by the electrode assembly 22 to gradually decrease along the region away from the axis of the electrode assembly 22 to the region near the axis. This can improve the problem of heat accumulation in the inner ring 22a of the electrode assembly 22, reduce the risk of thermal runaway in the battery cell 20, and thus improve the reliability of the battery cell 20 and the battery device 100a.

[0109] In some embodiments, the thickness of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness located in the outer ring 22b of the electrode assembly 22. The thickness of the substrate 23 of the other of the positive electrode 221 and the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is less than the thickness located in the outer ring 22b of the electrode assembly 22.

[0110] In this design, the length of the thicker portion of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 can be equal to the length of the thinner portion of the substrate 23 of the other. Furthermore, the length of the thinner portion of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 can be equal to the length of the thicker portion of the substrate 23 of the other. This ensures that the thicknesses of the positive electrode 221 and the negative electrode 222 are complementary in the inner ring 22a and outer ring 22b of the electrode assembly 22, respectively. This improves the consistency of the gap and other dimensions between the inner ring 22a and the outer ring 22b of the electrode assembly 22. Furthermore, when the number of rings in the inner ring 22a and the outer ring 22b is the same, the difference between the radial dimensions of the inner ring 22a and the outer ring 22b of the electrode assembly 22 can be reduced.

[0111] Specifically, if the thickness of the substrate 23 of the positive electrode 221 located in the inner ring 22a of the electrode assembly 22 is greater than the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22, then the thickness of the substrate 23 of the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is less than the thickness of the substrate 23 located in the outer ring 22b of the electrode assembly 22.

[0112] By making the thickness of the substrate 23 of one of the positive electrode 221 and the negative electrode 222 in the inner ring 22a of the electrode assembly 22 greater than the thickness in the outer ring 22b of the electrode assembly 22, and making the thickness of the substrate 23 of the other of the positive electrode 221 and the negative electrode 222 in the inner ring 22a of the electrode assembly 22 less than the thickness in the outer ring 22b of the electrode assembly 22, the thicknesses of the positive electrode 221 and the negative electrode 222 are complementary in the inner ring 22a and outer ring 22b of the electrode assembly 22, respectively, it is possible to improve... The consistency of the gap between the inner ring 22a and the outer ring 22b of the high-electrode assembly 22 reduces the difference between the radial dimensions of the inner ring 22a and the outer ring 22b of the electrode assembly 22 when the number of inner rings 22a and the outer ring 22b is the same. This makes the structure of the electrode assembly 22 more compact, which not only improves the energy density of the battery cell 20, but also reduces the stress difference between the inner ring 22a and the outer ring 22b of the electrode assembly 22, thereby improving the stability of the battery cell 20.

[0113] This application further proposes a battery device 100a. The battery device 100a includes a battery housing 10 and a battery cell 20 as described in any of the above embodiments. The battery housing 10 has a second receiving space 10a. The battery cell 20 is disposed within the second receiving space 10a.

[0114] This application further proposes an electrical device. The electrical device includes the aforementioned battery device 100a.

[0115] According to some embodiments of this application, the battery device 100a described above can be used in electrical equipment. By configuring the substrate 23 of at least one of the positive electrode 221 and the negative electrode 222 such that the thickness of the inner ring 22a of the electrode assembly 22 is greater than the thickness of the outer ring 22b of the electrode assembly 22, the cross-sectional area of ​​at least a portion of the substrate 23 of the positive electrode 221 and the negative electrode 222 located in the inner ring 22a of the electrode assembly 22 is increased. This reduces the resistance of the inner ring 22a of the electrode assembly 22, thereby reducing the heat generation in the inner ring 22a of the electrode assembly 22. This improves the problem of heat accumulation in the inner ring 22a of the electrode assembly 22, reduces the risk of thermal runaway in the battery cell 20, and ultimately improves the reliability of the battery cell 20 and the battery device 100a.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, The battery cell includes: The housing has a first receiving space and a first opening communicating with the first receiving space; Electrode assembly, disposed within the first accommodating space; and An end cap is attached to the housing and closes the first opening; The electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet stacked and wound together. The substrate of at least one of the positive electrode sheet and the negative electrode sheet has a thickness greater in the inner circle of the electrode assembly than in the outer circle of the electrode assembly.

2. The battery cell according to claim 1, characterized in that, The thickness of the substrate of one of the positive electrode and the negative electrode in the inner circle is greater than the thickness in the outer circle; the thickness of the substrate of the other of the positive electrode and the negative electrode in the inner circle is equal to the thickness in the outer circle.

3. The battery cell according to claim 2, characterized in that, One of them is the positive electrode, and the other is the negative electrode.

4. The battery cell according to claim 2, characterized in that, One of them is the negative electrode, and the other is the positive electrode.

5. The battery cell according to claim 1 or 2, characterized in that, The substrate includes a first base region and a second base region connected to the first base region. The first base region and the second base region are arranged along the length direction of the substrate, and the first base region is arranged relative to the second base region closer to the axis of the electrode assembly. The thickness of the first base region is greater than the thickness of the second base region.

6. The battery cell according to claim 5, characterized in that, The ratio between the dimension of the first base region along the length direction and the dimension of the second base region along the length direction is 1:0.01 to 1:

100.

7. The battery cell according to claim 6, characterized in that, The ratio between the dimension of the first base region along the length direction and the dimension of the second base region along the length direction is 1:3 to 1:

1.

8. The battery cell according to claim 5, characterized in that, The thickness of the first base region is greater than or equal to 2 μm; the thickness of the second base region is greater than or equal to 2 μm.

9. The battery cell according to claim 5, characterized in that, The substrate includes a copper foil substrate with a thickness of 3μm to 8μm.

10. The battery cell according to claim 9, characterized in that, The copper foil substrate includes a first base region and a second base region, wherein the difference between the thickness of the first base region and the thickness of the second base region is 1 μm to 2 μm.

11. The battery cell according to claim 5, characterized in that, The substrate includes an aluminum foil substrate with a thickness of 10 μm to 20 μm.

12. The battery cell according to claim 11, characterized in that, The aluminum foil substrate includes a first base region and a second base region; wherein the difference between the thickness of the first base region and the thickness of the second base region is 1 μm to 3 μm.

13. The battery cell according to claim 5, characterized in that, The positive electrode and the negative electrode also include a coating layer disposed on the surface of the substrate; The thickness of the coating layer located in the first base region is less than the thickness of the coating layer located in the second base region.

14. The battery cell according to any one of claims 1 to 4, characterized in that, The substrate includes multiple base regions, which are arranged sequentially along the length of the substrate. Wherein, the thickness of the plurality of base regions of the substrate of at least one of the positive electrode and the negative electrode gradually decreases along the length direction from the first end of the substrate to the second end of the substrate; the first end is disposed near the axis of the electrode assembly relative to the second end.

15. The battery cell according to claim 1, characterized in that, The thickness of the substrate of one of the positive electrode and the negative electrode in the inner circle is greater than the thickness in the outer circle; the thickness of the substrate of the other of the positive electrode and the negative electrode in the inner circle is less than the thickness in the outer circle.

16. A battery device, characterized in that, The battery device includes: The battery housing forms a second receiving space; and The battery cell as described in any one of claims 1 to 15, wherein the battery cell is disposed within the second accommodating space.

17. An electrical appliance, characterized in that, The electrical equipment includes: The battery device as claimed in claim 16.

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