Cylindrical battery monomer, battery and power utilization device

Abstract

The utility model relates to a cylindrical battery monomer, a battery and a power utilization device, the cylindrical battery monomer comprises a shell and an electrode assembly accommodated in the shell, the shell comprises a side wall, and the side wall is arranged around the electrode assembly; the electrode assembly comprises a main body part, the main body part comprises a middle area and two end areas which are arranged in the axial direction of the main body part, the middle area is located between the two end areas, and in the radial direction of the main body part, the distance between the outer surface of the middle area and the inner surface of the side wall is larger than the distance between the outer surface of the end areas and the inner surface of the side wall. According to the embodiment of the invention, the use reliability of the cylindrical battery monomer can be improved.

Description

Technical Field

[0001] The present application relates to the field of rechargeable and dischargeable batteries, and in particular to a cylindrical battery cell, a battery and an electrical device. Background Art

[0002] Battery cells have characteristics such as high capacity and are therefore widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc.

[0003] With the development of the battery field, the requirements for battery performance are gradually increasing, especially the reliability of battery cells needs to be further improved. Utility Model Content

[0004] The present application provides a cylindrical battery cell, a battery and an electrical device. The embodiments of the present application can improve the reliability of the cylindrical battery cell.

[0005] In the first aspect, an embodiment of the present application proposes a cylindrical battery cell, which includes an outer shell and an electrode assembly accommodated in the outer shell, wherein the outer shell includes a side wall, which is arranged around the electrode assembly; the electrode assembly includes a main body, the main body includes a middle area and two end areas arranged along its own axial direction, and the middle area is located between the two end areas, wherein, along the radial direction of the main body, the distance between the outer surface of the middle area and the inner surface of the side wall is greater than the distance between the outer surface of the end area and the inner surface of the side wall.

[0006] Therefore, the distance between the outer surface of the end area and the inner surface of the side wall of the embodiment of the present application is relatively smaller, and the distance between the outer surface of the middle area and the inner surface of the side wall is relatively larger, which reserves more sufficient expansion space for the middle area, can effectively reduce the squeezing effect of the main body on the side wall, and improve the reliability of the cylindrical battery cell.

[0007] In some embodiments, in a direction from the end region to the middle region, the distance between the outer surface of the middle region and the inner surface of the side wall decreases first and then increases.

[0008] Therefore, the distance between the outer surface of the middle area and the inner surface of the side wall of the embodiment of the present application shows a trend of first decreasing and then increasing, so that the gap becomes larger as it is closer to the center position of the middle area in the axial direction, and the reserved expansion space becomes larger, which can further reduce the risk of the middle area squeezing the outer shell and improve the reliability of the cylindrical battery cell.

[0009] In some embodiments, the side wall includes a first portion and a second portion arranged axially, the first portion is radially opposite to the middle region, the second portion radially protrudes from a surface of the first portion facing the main body, and the second portion is radially opposite to the end region.

[0010] Therefore, in the embodiment of the present application, the distance between the inner surface of the first part and the outer surface of the middle area is larger, which reserves more expansion space for the middle area, which is beneficial to reduce the risk of the middle area squeezing the outer shell and improve the reliability of the cylindrical battery cell.

[0011] In some embodiments, in a direction from the middle region to the end region, the distance between the outer surface of the end region and the inner surface of the side wall tends to increase.

[0012] Therefore, in the embodiment of the present application, the distance between the outer surface of the end area and the inner surface of the side wall tends to increase, so that the reserved expansion space tends to increase, which is beneficial to reduce the risk of the end area squeezing the outer shell and improve the reliability of the cylindrical battery cell.

[0013] In some embodiments, the number of the second parts is two, and the two second parts are respectively located on both sides of the first part along the axial direction.

[0014] Therefore, in the embodiment of the present application, the two end areas of the main body are respectively provided with second parts. Through the cooperation of the end area and the second part, it is beneficial to reduce the risk of the end area causing compression to the shell. At the same time, the second part can also improve the mechanical strength of the shell, enhance the deformation resistance of the shell, and further improve the reliability of the use of the cylindrical battery cell.

[0015] In some embodiments, a dimension of the first portion in the axial direction is 0.4 to 0.98 times a dimension of the sidewall in the axial direction.

[0016] Therefore, when the axial dimension of the first part in the embodiment of the present application is within the above range, it can provide more sufficient expansion space for the middle area, which is beneficial to further reduce the risk of the middle area squeezing the outer shell and improve the reliability of the cylindrical battery cell.

[0017] In some embodiments, the outer peripheral surface of the side wall is a cylindrical surface. During the charging process of the cylindrical battery cell, the expansion of the electrode assembly has little or no effect on the side wall, thereby improving the structural stability of the cylindrical battery cell.

[0018] In some embodiments, the inner surface of the side wall is a curved surface and is concave in the direction away from the electrode assembly. The curved surface of the side wall is set to reserve more sufficient expansion space for the middle area;

[0019] In some embodiments, the side walls are arranged with uniform thickness. When the electrode assembly exerts a compressive force on the side walls, the deformation of the side walls is more moderate, and stress concentration is less likely to occur, thereby improving the reliability of the side walls.

[0020] In some embodiments, in a direction from one of the two end regions to the other end region, the thickness of the side wall decreases first and then increases. By decreasing the thickness of the side wall first and then increasing, more sufficient expansion space is reserved for the middle region.

[0021] In some embodiments, the side wall protrudes in a direction away from the electrode assembly, which makes it easy to reserve more expansion space for the middle area.

[0022] In some embodiments, when the cylindrical battery cell is at a 100% charge state, the radial distance between the outer surface of the middle region and the inner surface of the side wall is a first middle distance; when the cylindrical battery cell is at a 0% charge state, the radial distance between the outer surface of the middle region and the inner surface of the side wall is a second middle distance; wherein the first middle distance is smaller than the second middle distance, and the difference between the first middle distance and the second middle distance is less than or equal to 0.05 mm.

[0023] Therefore, in the embodiment of the present application, when the difference between the first middle distance and the second middle distance is within the above range, the volume expansion of the cylindrical battery cell during charging is small, which is beneficial to improving the structural stability of the cylindrical battery cell and improving the reliability of the cylindrical battery cell.

[0024] In some embodiments, when the cylindrical battery cell is in a 100% state of charge, the radial spacing between the end region and the inner surface of the side wall is a first end spacing; when the cylindrical battery cell is in a 0% state of charge, the radial spacing between the end region and the inner surface of the side wall is a second end spacing; wherein the first end spacing is smaller than the second end spacing, and the difference between the first end spacing and the second end spacing is less than or equal to 0.05 mm.

[0025] Therefore, in the embodiment of the present application, when the difference between the first end spacing and the second end spacing is within the above range, the volume expansion of the cylindrical battery cell during charging is small, which is beneficial to improving the structural stability of the cylindrical battery cell and improving the reliability of the cylindrical battery cell.

[0026] In some embodiments, when the cylindrical battery cell is at a 100% charge state, the radial spacing between the outer surface of the middle region and the inner surface of the side wall is a first middle spacing; when the cylindrical battery cell is at a 0% charge state, the radial spacing between the outer surface of the middle region and the inner surface of the side wall is a second middle spacing, and the absolute value of the difference between the first middle spacing and the second middle spacing is a middle variable; when the cylindrical battery cell is at a 100% charge state, the radial spacing between the end region and the inner surface of the side wall is a first end spacing; when the cylindrical battery cell is at a 0% charge state, the radial spacing between the end region and the inner surface of the side wall is a second end spacing, and the absolute value of the difference between the first end spacing and the second end spacing is an end variable; wherein, the absolute value of the difference between the middle variable and the end variable is less than or equal to 0.05 mm.

[0027] Therefore, when the absolute value of the difference between the middle variable and the end variable of the embodiment of the present application is within the above range, the difference in the degree of volume expansion between the end area and the middle area of ​​the cylindrical battery cell during charging is small, so that the difference in the degree of volume expansion of the main body as a whole is small, which is not easy to cause local excessive extrusion of the shell, and the reliability of the use of the cylindrical battery cell is significantly improved.

[0028] In some embodiments, the base material of the side wall includes metal, and the thickness of the side wall is 0.3 mm to 1.2 mm.

[0029] Therefore, the side wall with the above thickness in the embodiment of the present application has excellent mechanical strength, is not easily deformed, and can improve the structural stability of the side wall, thereby improving the reliability of the cylindrical battery cell.

[0030] In some embodiments, a dimension of the housing in the axial direction is 1.3 to 2.5 times a dimension of the housing in the radial direction.

[0031] Therefore, when the shell in the embodiment of the present application meets the above-mentioned size requirements, the distance between the outer surface of the middle area and the inner surface of the side wall is greater than the distance between the outer surface of the end area and the inner surface of the side wall, so that the structural stability of the shell is higher, which can improve the reliability of the use of the cylindrical battery cell.

[0032] In some embodiments, the housing has an axial dimension of 50 mm to 150 mm.

[0033] In some embodiments, the radial dimension of the housing is 40 mm to 80 mm.

[0034] In some embodiments, the housing includes a shell and an end cover, the shell includes an integrally formed side wall and end wall, the end wall and the end cover are axially opposite, and the end cover is sealingly connected to the side wall.

[0035] In some embodiments, the electrode assembly includes a first pole ear and a second pole ear with opposite polarities, and the first pole ear and the second pole ear respectively protrude from the main body; the cylindrical battery cell also includes an electrode terminal insulated and arranged on the end wall, the electrode terminal is electrically connected to the second pole ear, and the end wall is electrically connected to the first pole ear.

[0036] In some embodiments, the electrode assembly includes a negative electrode plate, which includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector and containing a negative electrode active material, wherein the negative electrode active material includes silicon.

[0037] Therefore, in the embodiment of the present application, the negative electrode active material includes silicon, which can improve both the energy density and the reliability of the cylindrical battery cell.

[0038] In some embodiments, the mass content of silicon in the negative electrode film layer is 1% to 32%.

[0039] Therefore, in the embodiment of the present application, when the mass content of silicon element is within the above range, it is possible to improve both the energy density and the reliability of use of the cylindrical battery cell.

[0040] In a second aspect, an embodiment of the present application further provides a battery, the battery comprising a cylindrical battery cell according to any embodiment of the first aspect of the present application.

[0041] In a third aspect, an embodiment of the present application further proposes an electrical device, comprising a battery as in any embodiment of the second aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0043] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0044] Figure 2 An exploded schematic diagram of a battery provided in some embodiments of the present application;

[0045] Figure 3 for Figure 2 An exploded schematic diagram of a battery module is shown;

[0046] Figure 4 A schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of the present application;

[0047] Figure 5An exploded schematic diagram of a cylindrical battery cell provided in some embodiments of the present application;

[0048] Figure 6 is a cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of the present application;

[0049] Figure 7 yes Figure 6 An enlarged schematic diagram of a cylindrical battery cell at position A is shown;

[0050] Figure 8 is a schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

[0051] Fig. 9 is a cross-sectional schematic diagram of a cylindrical battery cell provided in some other embodiments of the present application;

[0052] Fig.10 1 is a cross-sectional schematic diagram of a cylindrical battery cell provided in some further embodiments of the present application.

[0053] The drawings are not necessarily drawn to scale.

[0054] The following are the descriptions of the reference numerals:

[0055] X, axial direction; Y, radial direction;

[0056] 1. Vehicle; 2. Battery; 3. Controller; 4. Motor; 5. Box; 5a. First box part; 5b. Second box part; 5c. Accommodation space; 6. Battery module; 7. Cylindrical battery cell;

[0057] 10. electrode assembly; 111. first electrode ear; 112. second electrode ear; 12. main body; 121. middle region; 122. end region; 122a. end face; 12a. outer surface;

[0058] 20, housing; 21, shell; 211, end wall; 212, side wall; 2121, first part; 2122, second part; 212a, outer peripheral surface; 212b, inner surface;

[0059] 22. End cap;

[0060] 30. Electrode terminal;

[0061] 40. Current collecting components. DETAILED DESCRIPTION

[0062] Hereinafter, embodiments of the cylindrical battery cell, battery, and electrical device of the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0063] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0064] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0065] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0066] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0067] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0068] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0069] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0070] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0071] The term "multiple" used in this application refers to more than two (including two). In the embodiment of this application, the battery cell may be a secondary battery, which refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0072] Battery cells may include but are not limited to lithium ion battery cells, sodium ion battery cells, sodium lithium ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium sulfur battery cells, magnesium ion battery cells, nickel metal hydride battery cells, nickel cadmium battery cells, lead storage battery cells, etc.

[0073] As an example, the battery cell may be a cylindrical battery cell, which refers to a battery cell having an outer shape that is a cylindrical structure or a structure similar to a cylindrical structure.

[0074] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0075] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0076] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0077] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0078] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0079] A cylindrical battery cell includes an electrode assembly and a shell. During the cyclic charge and discharge process, the electrode assembly may expand, causing compression on the shell. Basically, all parts of the electrode assembly will face the expansion problem, and the two ends of the electrode assembly along the axial direction may cause compression on the middle part of the electrode assembly along the axial direction, causing the internal stress in the middle part of the electrode assembly to increase, the degree of expansion to increase, and the squeezing force on the shell to increase, making the shell prone to deformation or even rupture in the middle position, affecting the reliability of the cylindrical battery cell.

[0080] In view of this, an embodiment of the present application proposes a cylindrical battery cell, in which the main body of the electrode assembly is divided into an end region and a middle region in the axial direction, the outer surface of the end region is spaced smaller than the inner surface of the side wall, and the outer surface of the middle region is spaced larger than the inner surface of the side wall of the cylindrical battery cell, leaving reserved space for the expansion of the electrode assembly, especially the reserved space in the middle region of the electrode assembly is relatively large, which can effectively reduce the extrusion effect of the electrode assembly on the outer shell and improve the reliability of the cylindrical battery cell.

[0081] The cylindrical battery cell described in the embodiments of the present application is suitable for use in batteries and electrical devices using the batteries.

[0082] The cylindrical battery cells, batteries and electrical devices disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed 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.

[0083] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0084] Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application.

[0085] like Figure 1 As shown, a battery 2 is disposed inside the vehicle 1, and the battery 2 may be disposed at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1, for example, the battery 2 may be used as an operating power source for the vehicle 1.

[0086] The vehicle 1 may further include a controller 3 and a motor 4 , wherein the controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1 .

[0087] In some embodiments of the present application, the battery 2 can not only serve as an operating power source for the vehicle 1, but also serve as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0088] Figure 2 Schematic diagram of an explosion of a battery provided in some embodiments of the present application. Figure 2 As shown, the battery 2 includes a box 5 and a cylindrical battery cell ( Figure 2 The cylindrical battery cells are contained in the box body 5.

[0089] The box 5 is used to accommodate cylindrical battery cells, and the box 5 can be of various structures. In some embodiments, the box 5 can include a first box portion 5a and a second box portion 5b, the first box portion 5a and the second box portion 5b cover each other, and the first box portion 5a and the second box portion 5b jointly define a storage space 5c for accommodating cylindrical battery cells. The second box portion 5b can be a hollow structure with one end open, the first box portion 5a is a plate-like structure, and the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c; the first box portion 5a and the second box portion 5b can also be hollow structures with one side open, and the open side of the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c. Of course, the first box portion 5a and the second box portion 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0090] In order to improve the sealing performance after the first box body part 5a and the second box body part 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body part 5a and the second box body part 5b.

[0091] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box.

[0092] In the battery 2, there can be one or more cylindrical battery cells. If there are multiple cylindrical battery cells, the multiple cylindrical battery cells can be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple cylindrical battery cells are both connected in series and in parallel. The multiple cylindrical battery cells can be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple cylindrical battery cells is accommodated in the box 5; of course, multiple cylindrical battery cells can also be connected in series, in parallel, or in mixed connection to form a battery module 6, and the multiple battery modules 6 are then connected in series, in parallel, or in mixed connection to form a whole, and accommodated in the box 5.

[0093] A cylindrical battery cell may be the smallest unit constituting a battery.

[0094] Figure 3 for Figure 2 Schematic diagram of the structure of the battery module shown.

[0095] In some embodiments, Figure 3 As shown, there are multiple cylindrical battery cells 7, and the multiple cylindrical battery cells 7 are first connected in series, in parallel, or in mixed connection to form a battery module 6. The multiple battery modules 6 are then connected in series, in parallel, or in mixed connection to form a whole, and are accommodated in a box.

[0096] The multiple cylindrical battery cells 7 in the battery module 6 can be electrically connected through a busbar component to achieve parallel connection, series connection or mixed connection of the multiple cylindrical battery cells 7 in the battery module. There can be one or more busbar components, each of which is used to electrically connect at least two cylindrical battery cells.

[0097] Figure 4 A schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of the present application; Figure 5 for Figure 4 An exploded schematic diagram of a cylindrical battery cell is shown.

[0098] like Figure 4 and Figure 5 As shown, in some embodiments, the cylindrical battery cell 7 includes an electrode assembly 10 and a housing 20 , and the electrode assembly 10 is accommodated in the housing 20 .

[0099] The outer shell 20 is a cylindrical structure, and includes a shell 21. The shell 21 is a cylindrical structure, and the shape of the corresponding electrode assembly 10 is also a cylindrical structure. The axial direction of the outer shell 20 is parallel to the axial direction of the electrode assembly 10, and the radial direction of the outer shell 20 is parallel to the radial direction of the electrode assembly 10.

[0100] In some embodiments, the axial dimension of the housing 20 is 1.3 to 2.5 times the radial dimension of the housing 20, such as 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, or a range consisting of any two of the above values. When the housing 20 meets the above size requirements, it is matched with the structural features of the cylindrical battery cell 7 (for example, the distance between the outer surface of the middle area and the inner surface of the side wall is greater than the distance between the outer surface of the end area and the inner surface of the side wall), so that the structural stability of the housing 20 is higher, which can improve the reliability of the use of the cylindrical battery cell.

[0101] Exemplarily, the axial dimension of the housing 20 is 50 mm to 150 mm, for example, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, 150 mm, or a range consisting of any two of the above values.

[0102] Exemplarily, the radial dimension of the housing 20 is 40 mm to 80 mm, such as 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, or a range consisting of any two of the above values.

[0103] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charge and discharge process of the cylindrical battery cell 7, active ions (such as lithium ions) are inserted and removed back and forth between the positive electrode and the negative electrode. Optionally, the electrode assembly 10 also includes a separator disposed between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0104] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material.

[0105] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0106] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, titanium, silver surface treated aluminum or stainless steel, etc. may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0107] As an example, when the cylindrical battery cell 7 of the embodiment of the present application is a lithium-ion battery, the positive electrode active material may include at least one of the following materials: phosphate, layered transition metal oxide and their respective modified compounds; optionally, the positive electrode active material may include layered transition metal oxide and their respective modified compounds, which is beneficial to improve the energy density of the cylindrical battery cell 7. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode film layers can also be used. These positive electrode active materials can be used alone or in combination of two or more.

[0108] Examples of phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to 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 iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0109] Layered transition metal oxides include those of the general formula Li a Ni b Co c M d O e A f At least one of the compounds and modified compounds thereof. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl.

[0110] Examples of layered transition metal oxides may include, but are not limited to, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2) and its modified compounds, etc.

[0111] When the cylindrical battery cell 7 of the embodiment of the present application is a sodium ion battery, the positive electrode active material may include but is not limited to at least one of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials.

[0112] As an example, the positive electrode active material for sodium ion batteries may include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2、NaNi 1 / 2 Mn 1 / 2 O2、Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2、NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials, general formula X p M' q (PO4) r O x Y 3-x In the general formula X p M' q (PO4) r O x Y 3-x , 0<p≤4, 0<q≤2, 1≤r≤3, 0≤x≤2, X includes H + , Li + 、Na + , K+ and NH4 + At least one of, M' is a transition metal cation, optionally at least one of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halogen anion, optionally at least one of F, Cl and Br.

[0113] In the embodiments of the present application, the modified compounds of the above-mentioned positive electrode active materials can be doping modification and / or surface coating modification of the positive electrode active materials, such as carbon coating modification, fast ion conductor coating modification, etc.

[0114] The cylindrical battery cell 7 is accompanied by the deintercalation and consumption of active ions such as Li during the charge and discharge process, and the molar content of Li is different when the cylindrical battery cell 7 is discharged to different states. In the examples of the positive electrode active materials in the present application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li may change after charge and discharge cycles.

[0115] In the examples of the present application regarding the positive electrode active materials, the molar content of oxygen O is only a theoretical value. The release of oxygen from the lattice will cause the molar content of oxygen O to change. In reality, the molar content of oxygen O will fluctuate.

[0116] In some embodiments, the positive electrode may be a foamed metal. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, or a carbon foam. When the foamed metal is used as the positive electrode, the positive electrode film layer may not be provided on the surface of the foamed metal, but of course, a positive electrode film layer may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or / and deposited in the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0117] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. The present application embodiment has no particular restrictions on the type of the positive electrode conductive agent. As an example, the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent in the positive electrode film layer is ≤5wt%.

[0118] In some embodiments, the positive electrode film layer may also optionally include a positive electrode binder. The embodiment of the present application has no particular restrictions on the type of positive electrode binder. As an example, the positive electrode binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and at least one of fluorine-containing acrylic resins. In some embodiments, the mass percentage of the positive electrode binder in the positive electrode film layer is ≤5wt%.

[0119] The positive electrode film layer is usually formed by coating the positive electrode slurry on the positive electrode current collector, drying and cold pressing. The positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder and any other components in a solvent and stirring them uniformly. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0120] In some embodiments, the negative electrode may be a negative electrode plate, which may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0121] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0122] As an example, the negative electrode current collector can be a metal foil, a foamed metal or a composite current collector. For example, as a metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. can be used. The foamed metal can be a foamed nickel, a foamed copper, a foamed aluminum, a foamed alloy, or a foamed carbon, etc. The composite current collector can include a polymer material base and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0123] As an example, the negative electrode active material may adopt the negative electrode active material for cylindrical battery cells 7 known in the art. As an example, the negative electrode active material may include at least one of the following materials: carbon material (for example, the carbon material includes at least one of artificial graphite, natural graphite, soft carbon, and hard carbon), silicon-based material, tin-based material, lithium titanate, etc. The silicon-based material may include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may include at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode film layers may also be used. These negative electrode film layers may be used alone or in combination of two or more.

[0124] In some embodiments, the negative electrode active material includes silicon, which may be present in the form of a silicon-based material, for example, the silicon-based material may include at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon compounds, silicon-nitrogen compounds, and silicon alloys. The introduction of silicon can improve the energy density of the cylindrical battery cell 7.

[0125] In some embodiments, the mass content of silicon in the negative electrode film layer is 1wt% to 32wt%, optionally 2% to 19%, and further optionally 6% to 13%. In the cylindrical battery cell 7 system, when the mass content of silicon is within the above range, the energy density of the cylindrical battery cell 7 can be improved; and the above negative electrode film layer will expand in volume during charging, which cooperates with the structural features of the cylindrical battery cell 7 (for example, the distance between the outer surface of the middle area and the inner surface of the side wall is greater than the distance between the outer surface of the end area and the inner surface of the side wall), so that the gap between the shell 20 and the middle area of ​​the electrode assembly 10 is larger, which can reserve more sufficient expansion space, reduce the squeezing effect on the shell 20, and improve the structural stability of the shell 20, thereby improving the reliability of the use of the cylindrical battery cell 7.

[0126] In the embodiments of the present application, the mass content of silicon in the negative electrode film layer has a meaning well known in the art, and can be detected by equipment and methods well known in the art, such as immersing the negative electrode plate in a solvent such as water, separating the negative electrode active material from the negative electrode current collector, and filtering to obtain various substances in the negative electrode film layer, which are used as test samples. The test samples are measured using an ICAP7400 inductively coupled plasma-emission spectrometer produced by Thermo Fisher Scientific, USA, and referring to GB / T30902-2014 standard to obtain the silicon content.

[0127] In some embodiments, the negative electrode film layer may further optionally include a negative electrode conductive agent. The present application embodiment has no particular restrictions on the type of the negative electrode conductive agent. As an example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the negative electrode conductive agent in the negative electrode film layer is ≤5wt%.

[0128] In some embodiments, the negative electrode film layer may further optionally include a negative electrode binder. The embodiment of the present application has no particular restrictions on the type of negative electrode binder. As an example, the negative electrode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage of the negative electrode binder in the negative electrode film layer is ≤5%.

[0129] In some embodiments, the negative electrode film layer may further include other additives. As an example, the other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc. In some embodiments, the mass percentage of the other additives in the negative electrode film layer is ≤2wt%.

[0130] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0131] In some embodiments, the separator includes a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical stability and mechanical stability can be selected.

[0132] The embodiments of the present application have no particular restrictions on the type of isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.

[0133] In some embodiments, the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0134] In some embodiments, the isolation membrane may include a porous base membrane and a coating layer disposed on at least one side of the porous base membrane, and the coating layer may include at least one of inorganic particles or organic particles.

[0135] The porous base membrane may include one or more of polyethylene and polypropylene.

[0136] The inorganic particles have good heat resistance and can improve the heat resistance of the separator as a whole. The inorganic particles will not undergo oxidation and reduction reactions with metal dendrites within the operating voltage range of the sodium ion battery. In other words, the inorganic particles are configured not to undergo oxidation and reduction reactions with alkali metals and / or alkaline earth metals at the nominal voltage of the sodium ion battery.

[0137] In some embodiments, the inorganic particles include one or more of boehmite γ-AlOOH, aluminum oxide Al2O3, aluminum hydroxide Al(OH)3, barium sulfate BaSO4, magnesium oxide MgO, magnesium hydroxide Mg(OH)2, calcium oxide CaO, cerium oxide CeO2, zirconium titanate SrTiO3, barium titanate BaTiO3, and magnesium fluoride MgF2.

[0138] In some embodiments, the organic particles include at least one of polystyrene, polyethylene, polyimide, melamine resin, phenolic resin, polypropylene, polyester (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyphenylene sulfide, polyaramid, polyamideimide, polyimide, copolymer of butyl acrylate and ethyl methacrylate, and mixtures thereof.

[0139] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte.

[0140] During the charge and discharge process of the battery cell, active ions are embedded and released back and forth between the positive electrode and the negative electrode, and the electrolyte plays a role in conducting active ions between the positive electrode and the negative electrode. The present application embodiment has no particular limitation on the type of electrolyte, which can be selected according to actual needs.

[0141] The electrolyte includes electrolyte salt and solvent. The types of electrolyte salt and solvent are not specifically limited and can be selected according to actual needs.

[0142] When the cylindrical battery cell 7 of the embodiment of the present application is a lithium ion battery, as an example, the electrolyte salt may include but is not limited to at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0143] When the cylindrical battery cell 7 of the embodiment of the present application is a sodium ion battery, as an example, the electrolyte salt may include but is not limited to at least one of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalatoborate (NaDFOB), sodium dioxalatoborate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorobis(oxalatophosphate) (NaDFOP) and sodium tetrafluorooxalatophosphate (NaTFOP).

[0144] As an example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

[0145] In some embodiments, the electrolyte may also optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, and additives that improve battery low temperature power performance.

[0146] like Figure 4 and Figure 5 As shown, in some embodiments, the electrode assembly 10 may be a wound structure or a laminated structure. Optionally, the electrode assembly 10 is a wound structure. The positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0147] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0148] 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 used to cover the opening.

[0149] The housing 21 is a component used to cooperate with the end cover 22 to form an internal cavity of the cylindrical battery cell 7. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte and other components.

[0150] The housing 21 and the end cap 22 may be independent components. For example, an opening may be provided on the housing 21, and the end cap 22 may cover the opening to form an internal cavity of the cylindrical battery cell 7.

[0151] The end cover 22 is connected to the housing 21 by welding, bonding, clamping or other methods.

[0152] The housing 21 may be open at one end or at both ends. In some examples, the housing 21 may be a structure with an opening at one end, and an end cap 22 is provided and covers the housing 21. In other examples, the housing 21 may be a structure with openings at both ends, and two end caps 22 are provided, and the two end caps 22 cover the two openings of the housing 21 respectively.

[0153] In some embodiments, the shell 21 includes a side wall 212 and an end wall 211 connected to the side wall 212 . The end wall 211 and the end cover 22 are opposite to each other along the axial direction of the cylindrical battery cell 7 . The end cover 22 is sealed to the side wall 212 . The side wall 212 is arranged around the electrode assembly 10 .

[0154] In some embodiments, end wall 211 and side wall 212 may have the same polarity.

[0155] In some embodiments, the end wall 211 and the side wall 212 may be an integrally formed structure, that is, the housing 21 is an integrally formed component. Of course, the end wall 211 and the side wall 212 may also be two components provided separately and then connected together by welding, riveting, bonding, etc.

[0156] From the appearance of the electrode assembly 10, the electrode assembly 10 includes a main body 12, a first pole ear 111 and a second pole ear 112. The first pole ear 111 and the second pole ear 112 have opposite polarities, and the first pole ear 111 and the second pole ear 112 protrude from the main body 12 respectively. The first pole ear 111 is a portion of the first pole sheet that is not coated with an active material layer, and the second pole ear 112 is a portion of the second pole sheet that is not coated with an active material layer. The first pole ear 111 and the second pole ear 112 are used to draw out the current in the main body 12. The first pole sheet and the second pole sheet have opposite polarities. In other words, one of the first pole sheet and the second pole sheet is a positive pole sheet, and the other of the first pole sheet and the second pole sheet is a negative pole sheet.

[0157] The first pole tab 111 is a negative pole tab, and the second pole tab 112 is a positive pole tab. The negative electrode current collector portion not coated with the active material layer in the negative electrode pole sheet is the negative electrode pole tab, and the active material coated by the negative electrode current collector in the negative electrode pole sheet constitutes the negative electrode film layer. The negative electrode film layer and the negative electrode current collector portion coated with the active material are part of the main body 12. The positive electrode current collector portion not coated with the active material layer in the positive electrode pole sheet is the positive electrode pole tab, and the active material coated by the positive electrode current collector in the positive electrode pole sheet constitutes the positive electrode film layer. The positive electrode film layer and the positive electrode current collector portion coated with the active material are part of the main body 12.

[0158] In some embodiments, the cylindrical battery cell 7 includes a first electrode lead-out portion and a second electrode lead-out portion, the first electrode lead-out portion is electrically connected to the first electrode tab 111 , and the second electrode lead-out portion is electrically connected to the second electrode tab 112 .

[0159] In the axial direction of the main body 12, the first electrode lead-out portion and the second electrode lead-out portion may also be located on both sides of the electrode assembly, or the first electrode lead-out portion and the second electrode lead-out portion may be located on the same side of the electrode assembly. For example, the second electrode lead-out portion includes an electrode terminal 30 insulated and arranged on the end wall 211, and the first electrode lead-out portion is the end wall 211.

[0160] The first electrode tab 111 and the second electrode tab 112 may extend from the same side of the main body 12 , or may extend from opposite sides respectively.

[0161] The first electrode tab 111 and the second electrode tab 112 may be respectively disposed at two sides of the main body 12 along the axial direction. In other words, the first electrode tab 111 and the second electrode tab 112 are respectively disposed at two ends of the electrode assembly 10 along the axial direction.

[0162] Optionally, the first pole lug 111 is wound around the central axis of the electrode assembly 10 for multiple turns, and the first pole lug 111 includes multiple turns of pole lug layers. After the winding is completed, the first pole lug 111 is generally cylindrical, and a gap is left between two adjacent turns of pole lug layers. The embodiment of the present application can process the first pole lug 111 to reduce the gap between the pole lug layers, so as to facilitate the connection of the first pole lug 111 with other conductive structures. For example, the embodiment of the present application can flatten the first pole lug 111 so that the end of the first pole lug 111 away from the main body 12 is gathered and gathered together; the flattening process forms a dense end face at one end of the first pole lug 111 away from the main body 12, reduces the gap between the pole lug layers, and facilitates the connection of the first pole lug 111 with other conductive structures. Alternatively, the embodiment of the present application can also fill the conductive material between two adjacent turns of pole lug layers to reduce the gap between the pole lug layers.

[0163] Optionally, the second pole tab 112 is wound around the central axis of the electrode assembly 10 for multiple turns, and the second pole tab 112 includes multiple turns of pole tab layers. Exemplarily, the second pole tab 112 is also flattened to reduce the gap between the pole tab layers of the second pole tab 112.

[0164] The first electrode tab 111 is electrically connected to the end cap 22 . The first electrode tab 111 may be directly electrically connected to the end cap 22 , or may be indirectly electrically connected to the end cap 22 through other conductive structures. The end cap 22 is electrically connected to the end wall 211 .

[0165] The second pole tab 112 is electrically connected to the electrode terminal 30 of the cylindrical battery cell 7, and the electrode terminal 30 is insulated and disposed on the end wall 211. The second pole tab 112 can be electrically connected to the electrode terminal 30 directly or indirectly through other conductive structures.

[0166] In some embodiments, the second electrode tab 112 can be directly connected to the electrode terminal 30, for example, by welding, abutting or other means. Alternatively, the second electrode tab 112 can also be indirectly connected to the electrode terminal 30 through other conductive components (such as the current collecting member 40) to achieve electrical connection between the second electrode tab 112 and the electrode terminal 30.

[0167] The electrode terminal 30 is insulated and disposed on the end wall 211 . Therefore, the electrode terminal 30 and the end wall 211 may have different polarities, and the electrode terminal 30 and the end wall 211 may serve as different output poles.

[0168] The end wall 211 may be provided with an electrode lead-out hole, and the electrode terminal 30 is insulated and disposed on the end wall 211 and installed in the electrode lead-out hole, and the electrode lead-out hole facilitates the electrical energy of the electrode assembly 10 to be led out of the shell 21 .

[0169] The central axis of the electrode assembly 10 is a virtual straight line. The central axis of the electrode assembly 10 may pass through the electrode lead-out hole, or may be staggered with the electrode lead-out hole, which is not limited in the present application.

[0170] The electrode terminal 30 may be fixed to the end wall 211. The electrode terminal 30 may be fixed as a whole to the outside of the end wall 211, or may extend into the interior of the housing 20 through the electrode lead-out hole.

[0171] When the first pole tab 111 is a negative pole tab and the second pole tab 112 is a positive pole tab, the end wall 211 is the negative output pole of the cylindrical battery cell 7, and the electrode terminal 30 is the positive output pole of the cylindrical battery cell 7. When the first pole tab 111 is a positive pole tab and the second pole tab 112 is a negative pole tab, the end wall 211 is the positive output pole of the cylindrical battery cell 7, and the electrode terminal 30 is the negative output pole of the cylindrical battery cell 7.

[0172] Figure 6 is a cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of the present application, Figure 7 yes Figure 6 The enlarged schematic diagram of the cylindrical battery cell at A is shown. Figure 8 It is a cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application.

[0173] like Figures 6 to 8As shown, in some embodiments, the cylindrical battery cell 7 includes a shell 20 and an electrode assembly 10 accommodated in the shell 20, the shell 20 includes a side wall 212, and the side wall 212 is arranged around the electrode assembly 10; the electrode assembly 10 includes a main body 12, the main body 12 includes a middle area 121 and two end areas 122 arranged along its own axial direction, and the middle area 121 is located between the two end areas 122; wherein, along the radial direction of the main body 12, the distance between the outer surface of the middle area 121 and the inner surface 212b of the side wall 212 is greater than the distance between the outer surface of the end area 122 and the inner surface 212b of the side wall 212.

[0174] Figure 6 and Figure 7 The X direction shown in the figure represents the axial direction of the main body 12, which is the axial direction of the electrode assembly 10 and is parallel to the axial direction of the housing 20. The Y direction represents the radial direction of the main body 12, which is the radial direction of the electrode assembly 10 and is parallel to the radial direction of the housing 20. The X direction is perpendicular to the Y direction.

[0175] During the charging process of the cylindrical battery cell 7, the main body 12 may expand in volume, so that the main body 12 is at risk of squeezing the side wall 212; the internal stress of the main body 12 at various locations in the radial direction Y is basically the same; since the end region 122 has a higher degree of freedom of expansion, in the axial direction X, the end region 122 of the main body 12 may further squeeze the middle region 121, thereby aggravating the internal stress of the middle region 121 and expanding to a greater extent in the radial direction Y, resulting in a greater risk of the middle region 121 squeezing and damaging the side wall 212. In the embodiment of the present application, a gap is provided between the main body 12 and the side wall 212. The existence of the gap reserves expansion space for the main body 12, reduces the risk of the main body 12 squeezing the side wall 212, and further makes the distance between the outer surface of the end area 122 and the inner surface 212b of the side wall 212 relatively smaller, and the distance between the outer surface of the middle area 121 and the inner surface 212b of the side wall 212 relatively larger, thereby reserving more sufficient expansion space for the middle area 121, which can effectively reduce the squeezing effect of the main body 12 on the side wall 212 and improve the reliability of the cylindrical battery cell 7.

[0176] In the embodiment of the present application, the distance between the outer surface of the middle area 121 and the inner surface 212b of the side wall 212 is greater than the distance between the outer surface of the end area 122 and the inner surface 212b of the side wall 212. It can be understood that the minimum value of the distance between the outer surface of the middle area 121 and the inner surface 212b of the side wall 212 is greater than the maximum value of the distance between the outer surface of the end area 122 and the inner surface 212b of the side wall 212.

[0177] The inner surface 212b of the side wall 212 is the surface of the side wall 212 facing the main body 12, and the outer surface 12a of the main body 12 can also be understood as the surface of the main body 12 facing the side wall 212. Specifically, for example, the end region 122 includes an end surface 122a that faces away from the middle region 121. The dimension of the main body 12 in the axial direction X is defined as L. The position of the end surface 122a of one of the two end regions 122 is the origin, and the position of the end surface 122a of the other end region 122 is L. The distance between the main body 12 and the side wall 212 at L / 3 of the main body 12 is tested. The distance between multiple positions of the outer surface 12a of the main body 12 at L / 3 and the corresponding side wall 212 can be tested, and the average value is taken as the distance at that location.

[0178] Figure 7 In the figure, W1 represents the distance between the outer surface at one position in the end region 122 and the inner surface 212b of the side wall 212; W2 represents the distance between the outer surface at one position in the middle region 121 and the inner surface 212b of the side wall 212, and W2 is greater than W1.

[0179] The end region 122 is a structure having a certain size in the axial direction X. The two end faces 122a122a of the main body 12 opposite to each other in the axial direction X are the end faces 122a122a of the two end regions 122, respectively. The end region 122 is the region between the end faces 122a122a and the distance H2 from the end face 122a. For example, H2 may be 20 mm, that is, the size of the end region 122 in the axial direction X is 20 mm. Figure 8 H2 shown in FIG. 1 represents the dimension of the end region 122 in the axial direction X.

[0180] The middle region 121 is a structure having a certain size in the axial direction X. The middle region 121 is the region from the middle section to the distance H1 from the middle section. The middle section is a section including the center point of the main body 12 on its own axis, and the middle section is perpendicular to the axis of the main body 12. For example, H1 can be 5 mm, 2H1 is 10 mm, that is, the size of the middle region 121 in the axial direction X is 10 mm. Figure 8 2H1 shown in the figure represents the size of the middle region 121 in the axial direction X, M represents the axis of the main body 12 , and N represents a line located in the middle section of the main body 12 .

[0181] The main body 12 of the electrode assembly 10 includes an end region 122 and a middle region 121, that is, the main body 12 includes an end region 122, a middle region 121, and an end region 122 arranged along the axial direction X; the end region 122 may be directly connected to the middle region 121, that is, the main body 12 includes an end region 122, a middle region 121, and an end region 122 arranged in sequence along the axial direction X. Of course, a connection region may also be included between the end region 122 and the middle region 121, for example, the main body 12 includes an end region 122, a connection region, a middle region 121, a connection region, and an end region 122 arranged along the axial direction X.

[0182] In some embodiments, in the direction from the end region 122 to the middle region 121, the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 first decreases and then increases. The direction from the end region 122 to the middle region 121 is parallel to the axial direction X of the main body 12, but the direction from the end region 122 to the middle region 121 is a single direction.

[0183] The distance between the outer surface of the middle area 121 and the inner surface 212b of the side wall 212 first decreases and then increases, so that the closer the gap is to the center position of the middle area 121 in the axial direction X, the larger the reserved expansion space is, which can further reduce the risk of the middle area 121 squeezing the outer shell 20 and improve the reliability of the cylindrical battery cell 7.

[0184] In the embodiment of the present application, the shell 20 can be set to a variety of structural forms to increase the expansion space of the middle area 121. The structural form of the shell 20 is described below.

[0185] like Figures 6 to 8 As shown, in some embodiments, the side wall 212 includes a first portion 2121 and a second portion 2122 arranged along the axial direction X, the first portion 2121 is opposite to the middle area 121 along the radial direction Y, the second portion 2122 protrudes from the surface of the first portion 2121 facing the main body 12 along the radial direction Y, and the second portion 2122 is opposite to the end area 122 along the radial direction Y.

[0186] During the charging process of the cylindrical battery cell 7, the end region 122 expands toward the second part 2122 in the radial direction Y, and the middle region 121 expands toward the first part 2121 in the radial direction Y, and the middle region 121 expands to a greater extent; the second part 2122 protrudes from the first part 2121 along the radial direction Y, and the distance between the inner surface 212b of the second part 2122 and the outer surface of the end region 122 is relatively smaller, and the distance between the inner surface 212b of the first part 2121 and the outer surface of the middle region 121 is larger, which reserves more expansion space for the middle region 121, which is beneficial to reduce the risk of the middle region 121 squeezing the outer shell 20 and improving the reliability of the cylindrical battery cell 7.

[0187] Optionally, the first portion 2121 may further be opposite to a portion of the end region 122 along the radial direction Y, and the second portion 2122 may be opposite to another portion of the end region 122 along the radial direction Y.

[0188] Optionally, in the direction from the middle region 121 to the end region 122, the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 increases. The direction from the middle region 121 to the end region 122 is parallel to the axial direction X of the main body 12, but the direction from the middle region 121 to the end region 122 is a single direction, which is parallel to the direction from the end region 122 to the middle region 121, but in the opposite direction.

[0189] The end region 122 is a structure with a certain size in the axial direction X. The closer to the end face 122a of the end region 122, the higher the expansion freedom and the smaller the internal stress. On the contrary, along the axial direction X, as the distance from the end face 122a increases, the internal stress increases, and the degree of expansion in the radial direction Y increases. In the embodiment of the present application, the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 tends to increase, so that the reserved expansion space tends to increase, which is beneficial to reduce the risk of the end region 122 causing compression of the outer shell 20 and improve the reliability of the cylindrical battery cell 7.

[0190] In some embodiments, the second portion 2122 may be provided as at least one, for example, one or two.

[0191] Exemplarily, when the second portion 2122 is provided as one, the second portion 2122 may be located at any end of the main body 12 along the axial direction X.

[0192] Alternatively, illustratively, two second parts 2122 are provided, and the two second parts 2122 are respectively located on both sides of the first part 2121 along the axial direction X. When two second parts 2122 are provided, the two end regions 122 of the main body 12 are respectively provided with second parts 2122. The cooperation between the end regions 122 and the second parts 2122 is conducive to reducing the risk of the end regions 122 causing compression to the housing 20. At the same time, the second parts 2122 can also improve the mechanical strength of the housing 20, enhance the anti-deformation ability of the housing 20, and further enhance the reliability of the cylindrical battery cell 7.

[0193] In some embodiments, the dimension of the first portion 2121 along the axial direction X is 0.4 to 0.98 times the dimension of the side wall 212 along the axial direction X, for example, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.98 or a range consisting of any of the above values. Figure 6 L1 shown in the figure is the dimension of the first portion 2121 along the axial direction X, and L0 is the dimension of the side wall 212 along the axial direction X.

[0194] When the dimension of the first portion 2121 along the axial direction X is within the above range, it can provide more sufficient expansion space for the middle region 121 , which is beneficial to further reduce the risk of the middle region 121 squeezing the outer shell 20 and improve the reliability of the cylindrical battery cell 7 .

[0195] In some embodiments, the outer circumferential surface 212a of the side wall 212 is a cylindrical surface, so that the cylindrical battery cell 7 is a standard cylindrical structure, which means that during the charging process of the cylindrical battery cell 7, the side wall 212 will basically not deform, or the first part 2121 and the second part 2122 have a small expansion deformation degree and a small deformation difference. In other words, the expansion of the electrode assembly 10 has little effect on the side wall 212, or even no effect, so that the structural stability of the cylindrical battery cell 7 is improved; under this structural form, the side wall 212 is set to a non-uniform thickness, and the inner surface 212b of the side wall 212 is set to be non-flat, so that more sufficient expansion space is reserved for the middle area 121. Of course, in other embodiments, the outer circumferential surface 212a of the side wall 212 may also be a curved surface convex in the direction away from the electrode assembly 10. In the above embodiments of the present application, the outer circumferential surface 212a of the side wall 212 and the inner surface 212b of the side wall 212 are opposite to each other along the radial direction Y.

[0196] Fig. 9 It is a cross-sectional schematic diagram of a cylindrical battery cell provided in some other embodiments of the present application.

[0197] like Fig. 9As shown, in other embodiments, the inner surface 212b of the side wall 212 is a curved surface, that is, the surface of the side wall 212 facing the electrode assembly 10 is a curved surface, and is concave in the direction away from the electrode assembly 10. By setting the curved surface of the side wall 212, more sufficient expansion space is reserved for the middle area 121; specifically, the side wall 212 portion opposite to the middle area 121 can be set to be relatively more deeply concave, and the side wall 212 portion opposite to the end area 122 can be set to be relatively shallower.

[0198] For example, the sidewall 212 may be configured with uniform thickness or non-uniform thickness.

[0199] When the side wall 212 is set to be of equal thickness, the formation process of the side wall 212 is simpler, and when the electrode assembly 10 exerts an extrusion force on the side wall 212, the deformation of the side wall 212 is more moderate, and stress concentration is less likely to occur, which can improve the reliability of the use of the side wall 212. Optionally, along the radial direction Y, the side wall 212 protrudes in the direction away from the electrode assembly 10, and the side wall 212 presents a slightly convex structure as a whole. Specifically, the outer peripheral surface 212a of the side wall 212 can be a curved surface, which protrudes in the direction away from the electrode assembly 10. Figure 8 The structure in which the side walls 212 are arranged with equal thickness is shown.

[0200] Fig.10 1 is a cross-sectional schematic diagram of a cylindrical battery cell provided in some further embodiments of the present application.

[0201] like Fig.10 As shown, when the side wall 212 is set to be non-uniform thickness, the thickness of the side wall 212 decreases first and then increases in the direction from one of the two end regions 122 to the other end region 122. The thickness of the side wall 212 decreases first and then increases, thereby reserving more sufficient expansion space for the middle region 121. Specifically, a larger gap can be correspondingly set at the position of the middle region 121 to reserve more sufficient expansion space.

[0202] Optionally, along the radial direction Y, the side wall 212 protrudes in the direction away from the electrode assembly 10, and the side wall 212 as a whole presents a slightly convex structure, which is easy to achieve to reserve a larger expansion space for the middle area 121. Specifically, the outer peripheral surface 212a of the side wall 212 can be a curved surface, which protrudes in the direction away from the electrode assembly 10. Of course, when the side wall 212 is set to a non-uniform thickness, the outer peripheral surface of the side wall 212 can be a cylindrical surface.

[0203] In the above embodiments of the present application, the spacing test is performed when the cylindrical battery cell 7 is in a 0% state of charge SOC, and the test can be performed using equipment and methods known in the art. The spacing test in this state can be performed using equipment and methods known in the art. Specifically, at 25°C, the cylindrical battery cell 7 is discharged at 0.33C to 2.5V, and then discharged at 0.1C to 2.5V. At this time, the cylindrical battery cell 7 is in a 0% state of charge. The cylindrical battery cell 7 in a 0% state of charge is placed in an X-ray computed tomography scanner (brand: GE, model: Phoenix Nanotom M), and tested in accordance with ISO 15708:2002 standard to obtain a computed tomography image of the cylindrical battery cell 7 in the axial direction X and the radial direction Y. The spacing between each part of the side wall 212 and the main body 12 is measured according to the image, thereby measuring the spacing between the middle area 121 and the side wall 212, and measuring the spacing between the end area 122 and the side wall 212.

[0204] Principle of X-ray computed tomography scanner: When an X-ray beam with a certain energy and intensity passes through the cylindrical battery cell 7, a tomographic image is obtained through an image reconstruction algorithm according to the different attenuation and distribution of the X-ray beam in the object being detected, and finally a three-dimensional image of the sample is obtained by computer information processing and image reconstruction technology.

[0205] In some embodiments, when the cylindrical battery cell 7 is in a 100% charge state, the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 along the radial direction Y is a first middle distance; when the cylindrical battery cell 7 is in a 0% charge state, the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 along the radial direction Y is a second middle distance; wherein, the first middle distance is smaller than the second middle distance, and the difference between the first middle distance and the second middle distance is less than or equal to 0.05 mm.

[0206] The negative electrode active material in the cylindrical battery cell 7 may expand in volume during the charging process. When the cylindrical battery cell 7 is at 100% SOC, the volume expansion of the negative electrode active material is relatively large. In this case, the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 along the radial direction Y is the first middle distance. Correspondingly, when the cylindrical battery cell 7 is at 0% SOC, the volume expansion of the negative electrode active material is relatively small. In this case, the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 along the radial direction Y is the second middle distance. When the difference between the first middle distance and the second middle distance is within the above range, the volume expansion of the cylindrical battery cell 7 during the charging process is small, which is conducive to improving the structural stability of the cylindrical battery cell 7 and improving the reliability of the use of the cylindrical battery cell 7.

[0207] Exemplarily, the difference between the first middle spacing and the second middle spacing is less than or equal to 0.05 mm, for example, 0.05 mm, 0.045 mm, 0.04 mm, 0.035 mm, 0.03 mm, 0.025 mm, 0.02 mm, 0.015 mm, 0.01 mm, 0.005 mm, 0 or a range consisting of any two of the above values.

[0208] The difference between the first middle distance and the second middle distance can be calculated by measuring the distance between the same position of the middle region 121 and the side wall 212 at different charge states. Further, the difference between the first end distance and the second end distance can be calculated by measuring multiple distances between multiple positions of the middle region 121 and the side wall 212 at different charge states, and averaging the multiple distances as the difference between the first end distance and the second end distance; for example, the difference between the distance between the first position of the middle region 121 and the side wall 212 at different charge states is measured as the first distance, and the difference between the distance between the second position of the middle region 121 and the side wall 212 at different charge states is measured as the second distance, and the average of the first distance and the second distance is the difference between the first middle distance and the second middle distance.

[0209] In the embodiment of the present application, the spacing test of the cylindrical battery cell 7 at 100% state of charge SOC can be tested by using equipment and methods known in the art. Specifically, at 25°C, the cylindrical battery cell 7 prepared above is charged to 4.25V at 0.33C, and then charged to 4.25V at 0.1C. At this time, the cylindrical battery cell 7 is at 100% state of charge. The cylindrical battery cell 7 at 100% state of charge is placed in an X-ray computed tomography scanner (brand: GE, model: PhoenixNanotom M), and tested with reference to ISO 15708:2002 standard to obtain a computed tomography image of the cylindrical battery cell 7 in the axial direction X and the radial direction Y. The spacing between each part of the side wall 212 and the main body 12 is measured according to the image, thereby measuring the spacing between the outer surface of the middle area 121 and the inner surface 212b of the side wall 212, and measuring the spacing between the outer surface of the end area 122 and the inner surface 212b of the side wall 212.

[0210] In some embodiments, when the cylindrical battery cell 7 is in a 100% charge state, the distance between the end region 122 and the inner surface 212b of the side wall 212 along the radial direction Y is a first end distance; when the cylindrical battery cell 7 is in a 0% charge state, the distance between the end region 122 and the inner surface 212b of the side wall 212 along the radial direction Y is a second end distance; wherein, the first end distance is smaller than the second end distance, and the difference between the first end distance and the second end distance is less than or equal to 0.05 mm.

[0211] When the cylindrical battery cell 7 is at 100% SOC, the volume expansion of the negative electrode active material is relatively large. In this case, the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 along the radial direction Y is the first end distance. Correspondingly, when the cylindrical battery cell 7 is at 0% SOC, the volume expansion of the negative electrode active material is relatively small. In this case, the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 along the radial direction Y is the second end distance. When the difference between the first end distance and the second end distance is within the above range, the volume expansion of the cylindrical battery cell 7 is small during the charging process, which is conducive to improving the structural stability of the cylindrical battery cell 7 and improving the reliability of the use of the cylindrical battery cell 7.

[0212] Exemplarily, the difference between the first end spacing and the second end spacing is less than or equal to 0.05 mm, for example, 0.05 mm, 0.045 mm, 0.04 mm, 0.035 mm, 0.03 mm, 0.025 mm, 0.02 mm, 0.015 mm, 0.01 mm, 0.005 mm, 0 or a range consisting of any two of the above values.

[0213] The difference between the first end spacing and the second end spacing can be calculated by measuring the spacing between the same position of the end region 122 and the side wall 212 at different charge states. Further, the difference between the first end spacing and the second end spacing can be calculated by measuring multiple spacings between multiple positions of the end region 122 and the side wall 212 at different charge states, and taking the average value of the multiple spacings as the difference between the first end spacing and the second end spacing; for example, measuring the spacing between the first position of the end region 122 and the side wall 212 at different charge states as the first spacing, measuring the spacing between the second position of the end region 122 and the side wall 212 at different charge states as the second spacing, and the average value of the first spacing and the second spacing is the difference between the first end spacing and the second end spacing.

[0214] In some embodiments, the absolute value of the difference between the first middle spacing and the second middle spacing is the middle variable, and the absolute value of the difference between the first end spacing and the second end spacing is the end variable, wherein the absolute value of the difference between the middle variable and the end variable is less than or equal to 0.05 mm.

[0215] When the absolute value of the difference between the middle variable and the end variable is within the above range, the volume expansion degree of the end area 122 and the middle area 121 of the cylindrical battery cell 7 during charging is relatively small, so that the overall volume expansion degree of the main body 12 is relatively small, which is not easy to cause local excessive extrusion of the outer shell 20, and the reliability of the use of the cylindrical battery cell 7 is significantly improved.

[0216] Exemplarily, the absolute value of the difference between the middle variable and the end variable is less than or equal to 0.05 mm, for example, 0.05 mm, 0.045 mm, 0.04 mm, 0.035 mm, 0.03 mm, 0.025 mm, 0.02 mm, 0.015 mm, 0.01 mm, 0.005 mm, 0 or a range consisting of any two of the above values.

[0217] like Fig. 9 As shown, the material of the side wall 212 can be various. For example, the base material of the side wall 212 includes metal. For example, the metal includes but is not limited to copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the base material of the side wall 212 includes steel, such as stainless steel. The side wall 212 made of the above metal material has excellent mechanical strength and is not easily deformed, which can improve the structural stability of the side wall 212, thereby improving the reliability of the cylindrical battery cell 7. In each embodiment of the present application, the base material of the side wall 212 refers to the material that accounts for the largest proportion in the side wall.

[0218] In some embodiments, the base material of the side wall 212 includes metal, and the thickness of the side wall 212 is 0.3mm to 1.2mm. For example, the base material of the side wall 212 includes steel, and the thickness of the side wall 212 is 0.3mm to 1.2mm, such as 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.35mm, 0.38mm, 0.40mm, 0.42mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm or a range consisting of any two of the above values. The side wall 212 of the above thickness has excellent mechanical strength, is not easy to deform, can improve the structural stability of the side wall 212, and thus improve the reliability of the cylindrical battery cell 7.

[0219] In some embodiments, the side wall 212 is integrally formed with the end wall 211, which is conducive to simplifying the preparation process; the base material of the end wall 211 includes metal, and illustratively, the metal includes but is not limited to copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the base material of the end wall 211 includes steel, such as stainless steel. The end wall 211 made of the above metal material has excellent mechanical strength, is not easy to deform, and can improve the structural stability of the end wall 211, thereby improving the reliability of the cylindrical battery cell 7.

[0220] In some embodiments, the base material of the end wall 211 includes metal, and the thickness of the end wall 211 is 0.3 mm to 1.2 mm. For example, the base material of the end wall 211 includes steel, and the thickness of the end wall 211 is 0.3 mm to 1.2 mm.

[0221] As a specific embodiment of the present application, Figures 4 to 7 As shown, the cylindrical battery cell 7 includes a shell 20 and an electrode assembly 10 accommodated in the shell 20, the shell 20 includes a side wall 212, and the side wall 212 is arranged around the electrode assembly 10; the electrode assembly 10 includes a main body 12, the main body 12 includes a middle area 121 and two end areas 122 arranged along its own axial direction X, and the middle area 121 is located between the two end areas 122; the side wall 212 includes a first part 2121 and a second part 2122 arranged along the axial direction X, the first part 2121 is opposite to the middle area 121 along the radial direction Y, the second part 2122 protrudes from the surface of the first part 2121 facing the main body 12 along the radial direction Y, and the second part 2122 is opposite to the end area 122 along the radial direction Y; wherein, along the radial direction Y of the main body 12, the distance between the outer surface of the middle area 121 and the inner surface 212b of the side wall 212 is greater than the distance between the outer surface of the end area 122 and the inner surface 212b of the side wall 212. The distance between the inner surface 212b of the first part 2121 and the outer surface of the middle area 121 is larger, which reserves more expansion space for the middle area 121, helps to reduce the risk of the middle area 121 squeezing the outer shell 20 and improve the reliability of the cylindrical battery cell 7.

[0222] As another specific embodiment of the present application, Figure 8 As shown, the cylindrical battery cell 7 includes a shell 20 and an electrode assembly 10 accommodated in the shell 20, the shell 20 includes a side wall 212, and the side wall 212 is arranged around the electrode assembly 10; the electrode assembly 10 includes a main body 12, the main body 12 includes a middle area 121 and two end areas 122 arranged along its own axial direction X, and the middle area 121 is located between the two end areas 122; the inner surface 212b of the side wall 212 is an arc surface, and is recessed in the direction away from the electrode assembly 10; and the side wall 212 can be set with equal thickness; wherein, along the radial direction of the main body 12, the distance between the outer surface of the middle area 121 and the inner surface 212b of the side wall 212 is greater than the distance between the outer surface of the end area 122 and the inner surface 212b of the side wall 212. The distance between the inner surface 212b of the side wall 212 and the outer surface of the middle area 121 is larger, which reserves more expansion space for the middle area 121, helps to reduce the risk of the middle area 121 squeezing the outer shell 20 and improves the reliability of the cylindrical battery cell 7.

[0223] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0224] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein, but these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A cylindrical battery cell, characterized in that: The invention comprises a housing and an electrode assembly contained in the housing, wherein the housing comprises a side wall, and the side wall is arranged around the electrode assembly; The electrode assembly comprises a main body, wherein the main body comprises a middle region and two end regions arranged along its own axial direction, wherein the middle region is located between the two end regions; Wherein, along the radial direction of the main body, the distance between the outer surface of the middle region and the inner surface of the side wall is greater than the distance between the outer surface of the end region and the inner surface of the side wall.

2. The cylindrical battery cell according to claim 1, characterized in that: In a direction from the end region to the middle region, the distance between the outer surface of the middle region and the inner surface of the side wall first decreases and then increases.

3. The cylindrical battery cell according to claim 1, characterized in that: The side wall includes a first portion and a second portion arranged along the axial direction, the first portion is opposite to the middle region along the radial direction, the second portion protrudes from a surface of the first portion facing the main body along the radial direction, and the second portion is opposite to the end region along the radial direction.

4. The cylindrical battery cell according to claim 3, characterized in that: In a direction from the middle region to the end region, the distance between the outer surface of the end region and the inner surface of the side wall tends to increase.

5. The cylindrical battery cell according to claim 3, characterized in that: The number of the second parts is two, and the two second parts are respectively located at two sides of the first part along the axial direction.

6. The cylindrical battery cell according to claim 3, characterized in that: A dimension of the first portion along the axial direction is 0.4 to 0.98 times a dimension of the side wall along the axial direction.

7. The cylindrical battery cell according to claim 3, characterized in that: The outer peripheral surface of the side wall is a cylindrical surface.

8. The cylindrical battery cell according to claim 1, characterized in that: The inner surface of the side wall is a curved surface and is concave in a direction away from the electrode assembly.

9. The cylindrical battery cell according to claim 8, characterized in that: The side walls are arranged with equal thickness.

10. The cylindrical battery cell according to claim 8, characterized in that: In a direction from one of the two end regions to the other end region, the thickness of the side wall decreases first and then increases.

11. The cylindrical battery cell according to claim 8, characterized in that: The side wall protrudes in a direction away from the electrode assembly.

12. The cylindrical battery cell according to any one of claims 1 to 11, characterized in that: When the cylindrical battery cell is in a 100% charged state, the distance between the outer surface of the middle region and the inner surface of the side wall along the radial direction is a first middle distance; When the cylindrical battery cell is in a 0% state of charge, the distance between the outer surface of the middle region and the inner surface of the side wall along the radial direction is a second middle distance; The first middle spacing is smaller than the second middle spacing, and the difference between the first middle spacing and the second middle spacing is less than or equal to 0.05 mm.

13. The cylindrical battery cell according to any one of claims 1 to 11, characterized in that: When the cylindrical battery cell is in a 100% charged state, the distance between the end region and the inner surface of the side wall along the radial direction is a first end distance; When the cylindrical battery cell is in a 0% state of charge, the distance between the end region and the inner surface of the side wall along the radial direction is a second end distance; The first end spacing is smaller than the second end spacing, and the difference between the first end spacing and the second end spacing is less than or equal to 0.05 mm.

14. The cylindrical battery cell according to any one of claims 1 to 11, characterized in that: When the cylindrical battery cell is in a 100% charged state, the distance between the outer surface of the middle region and the inner surface of the side wall along the radial direction is a first middle distance; When the cylindrical battery cell is in a 0% state of charge, the distance between the outer surface of the middle region and the inner surface of the side wall along the radial direction is a second middle distance, and the absolute value of the difference between the first middle distance and the second middle distance is a middle variable; When the cylindrical battery cell is in a 100% charged state, the distance between the end region and the inner surface of the side wall along the radial direction is a first end distance; When the cylindrical battery cell is in a 0% state of charge, the distance between the end region and the inner surface of the side wall along the radial direction is a second end distance, and the absolute value of the difference between the first end distance and the second end distance is an end variable; The absolute value of the difference between the middle variable and the end variable is less than or equal to 0.05 mm.

15. The cylindrical battery cell according to any one of claims 1 to 11, characterized in that: The base material of the side wall includes metal, and the thickness of the side wall is 0.3 mm to 1.2 mm.

16. The cylindrical battery cell according to any one of claims 1 to 11, characterized in that: A dimension of the housing along the axial direction is 1.3 to 2.5 times a dimension of the housing along the radial direction.

17. The cylindrical battery cell according to any one of claims 1 to 11, characterized in that: The dimension of the housing along the axial direction is 50 mm to 150 mm; and / or The dimension of the housing along the radial direction is 40 mm to 80 mm.

18. The cylindrical battery cell according to any one of claims 1 to 11, characterized in that: The housing comprises a shell and an end cover, the shell comprises the side wall and the end wall which are integrally formed, the end wall and the end cover are opposite to each other along the axial direction, and the end cover is sealingly connected to the side wall.

19. The cylindrical battery cell according to claim 18, characterized in that: The electrode assembly comprises a first electrode tab and a second electrode tab with opposite polarities, wherein the first electrode tab and the second electrode tab protrude from the main body respectively; The cylindrical battery cell further includes an electrode terminal insulated and disposed on the end wall, the electrode terminal is electrically connected to the second electrode tab, and the end wall is electrically connected to the first electrode tab.

20. A battery, characterized in that: The invention comprises a cylindrical battery cell as claimed in any one of claims 1 to 19.

21. An electrical device, characterized in that: Comprising a battery as claimed in claim 20, the battery is used to provide electrical energy.

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