Cylindrical battery monomer, battery and power utilization device

Abstract

The invention 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

Cylindrical battery cell, battery and electric device TECHNICAL FIELD

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

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

[0003] With the development of the battery field, the requirements for battery performance are gradually increasing, and in particular the use reliability of battery cells needs to be further improved.

[0004] SUMMARY

[0005] The present application provides a cylindrical battery cell, a battery and an electric device, and the embodiments of the present application can improve the use reliability of the cylindrical battery cell.

[0006] In a first aspect, the embodiments of the present application provide a cylindrical battery cell, which 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 region and two end regions arranged along its own axial direction, the middle region is located between the two end regions, and along the radial direction of the main body part, 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.

[0007] Thus, the distance between the outer surface of the end region and the inner surface of the side wall of the embodiments of the present application is relatively smaller, and the distance between the outer surface of the middle region and the inner surface of the side wall is relatively larger, which reserves more sufficient expansion space for the middle region, can effectively reduce the extrusion of the main body part to the side wall, and improves the use reliability of the cylindrical battery cell.

[0008] In some embodiments, along the 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.

[0009] Thus, the distance between the outer surface of the middle region and the inner surface of the side wall of the embodiments of the present application decreases first and then increases, so that the gap is larger closer to the central position of the middle region in the axial direction, and the reserved expansion space is larger, which can further reduce the risk of extrusion of the middle region to the shell, and improve the use reliability of the cylindrical battery cell.

[0010] In some embodiments, the side wall comprises a first portion and a second portion arranged along the axial direction, the first portion is opposite to the middle region in the radial direction, the second portion protrudes from the surface of the main body portion in the radial direction, and the second portion is opposite to the end region in the radial direction.

[0011] Therefore, the distance between the inner surface of the first portion and the outer surface of the middle region is larger in the embodiments of the present application, more expansion space is reserved for the middle region, which is beneficial to reduce the risk of the middle region pressing the shell and improve the use reliability of the cylindrical battery monomer.

[0012] In some embodiments, the distance between the outer surface of the end region and the inner surface of the side wall increases in the direction from the middle region to the end region.

[0013] Therefore, the distance between the outer surface of the end region and the inner surface of the side wall increases in the embodiments of the present application, the reserved expansion space increases, which is beneficial to reduce the risk of the end region pressing the shell and improve the use reliability of the cylindrical battery monomer.

[0014] In some embodiments, the second portion is provided as two, and the two second portions are respectively located on both sides of the first portion in the axial direction.

[0015] Therefore, in the embodiments of the present application, the two end regions of the main body portion are respectively provided with the second portion, and through the cooperation of the end region and the second portion, it is beneficial to reduce the risk of the end region pressing the shell, and at the same time, the second portion can also improve the mechanical strength of the shell and the anti-deformation ability of the shell, further improving the use reliability of the cylindrical battery monomer.

[0016] In some embodiments, the size of the first portion in the axial direction is 0.4 to 0.98 times the size of the side wall in the axial direction.

[0017] Therefore, in the embodiments of the present application, when the size of the first portion in the axial direction is in the above range, more sufficient expansion space can be provided for the middle region, which is beneficial to further reduce the risk of the middle region pressing the shell and improve the use reliability of the cylindrical battery monomer.

[0018] In some embodiments, the outer peripheral surface of the side wall is a cylindrical surface. In the charging process of the cylindrical battery monomer, the expansion of the electrode assembly has little or even no effect on the side wall, so that the structural stability of the cylindrical battery monomer is improved.

[0019] In some embodiments, the inner surface of the side wall is an arc surface, and is concave in the direction away from the electrode assembly. By providing the arc surface of the side wall, more sufficient expansion space is reserved for the middle region.

[0020] In some embodiments, the side wall is of uniform thickness. When the electrode assembly exerts a pressing force on the side wall, the deformation of the side wall is more moderate, and stress concentration is less likely to occur, thereby improving the reliability of the side wall.

[0021] In some embodiments, the thickness of the side wall decreases first and then increases in the direction from one of the two end regions to the other end region. The thickness of the side wall decreasing first and then increasing provides more sufficient expansion space for the middle region.

[0022] In some embodiments, the side wall protrudes in a direction away from the electrode assembly, and it is easy to provide more expansion space for the middle region.

[0023] In some embodiments, when the cylindrical battery cell is at 100% state of charge, 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 0% state of charge, 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 less 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.

[0024] Therefore, when the difference between the first middle distance and the second middle distance is within the above range in the embodiments of the present application, the cylindrical battery cell has a smaller degree of volume expansion during charging, which is beneficial to improving the structural stability of the cylindrical battery cell and improving the reliability of the cylindrical battery cell.

[0025] In some embodiments, when the cylindrical battery cell is at 100% state of charge, the radial distance between the end region and the inner surface of the side wall is a first end distance; when the cylindrical battery cell is at 0% state of charge, the radial distance between the end region and the inner surface of the side wall is a second end distance; wherein the first end distance is less 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.

[0026] Therefore, when the difference between the first end distance and the second end distance is within the above range in the embodiments of the present application, the cylindrical battery cell has a smaller degree of volume expansion during charging, which is beneficial to improving the structural stability of the cylindrical battery cell and improving the reliability of the cylindrical battery cell.

[0027] In some embodiments, the outer surface of the middle region and the inner surface of the side wall have a radial spacing of a first middle spacing when the cylindrical battery cell is at 100% state of charge, the outer surface of the middle region and the inner surface of the side wall have a radial spacing of a second middle spacing when the cylindrical battery cell is at 0% state of charge, the absolute value of the difference between the first middle spacing and the second middle spacing is a middle variable, the outer surface of the end region and the inner surface of the side wall have a radial spacing of a first end spacing when the cylindrical battery cell is at 100% state of charge, the outer surface of the end region and the inner surface of the side wall have a radial spacing of a second end spacing when the cylindrical battery cell is at 0% state of charge, the absolute value of the difference between the first end spacing and the second end spacing is an end variable, and the absolute value of the difference between the middle variable and the end variable is less than or equal to 0.05 mm.

[0028] Therefore, when the absolute value of the difference between the middle variable and the end variable is within the above range, the difference between the volume expansion degrees of the end region and the middle region of the cylindrical battery cell during charging is small, the difference between the volume expansion degrees of the entire main body is small, and the local over-pressing of the shell is unlikely to occur, thereby significantly improving the use reliability of the cylindrical battery cell.

[0029] In some embodiments, the base material of the side wall comprises metal, and the thickness of the side wall is 0.3 mm to 1.2 mm.

[0030] Therefore, the side wall with the above thickness in the embodiments of the present application has excellent mechanical strength and is unlikely to deform, thereby improving the structural stability of the side wall and the use reliability of the cylindrical battery cell.

[0031] In some embodiments, the axial dimension of the shell is 1.3 times to 2.5 times the radial dimension of the shell.

[0032] Therefore, when the shell satisfies the above size requirement in the embodiments of the present application, the spacing between the outer surface of the middle region and the inner surface of the side wall is greater than the spacing between the outer surface of the end region and the inner surface of the side wall, the structural stability of the shell is high, and the use reliability of the cylindrical battery cell is improved.

[0033] In some embodiments, the axial dimension of the shell is 50 mm to 150 mm.

[0034] In some embodiments, the radial dimension of the shell is 40 mm to 80 mm.

[0035] In some embodiments, the shell comprises a shell body and an end cover, the shell body comprises an integrally formed side wall and an end wall, the end wall and the end cover are opposite in the axial direction, and the end cover is sealingly connected to the side wall.

[0036] In some embodiments, the electrode assembly includes a first tab and a second tab of opposite polarity, the first tab and the second tab respectively protruding from the body portion; the cylindrical battery cell further includes an electrode terminal insulatedly arranged on the end wall, the electrode terminal being electrically connected to the second tab, and the end wall being electrically connected to the first tab.

[0037] In some embodiments, the electrode assembly includes a negative electrode tab, the negative electrode tab including a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector and containing a negative electrode active material, the negative electrode active material including silicon elements.

[0038] Therefore, in the embodiments of the present application, the negative electrode active material includes silicon elements, which can improve the energy density and the use reliability of the cylindrical battery cell.

[0039] In some embodiments, the mass content of the silicon elements in the negative electrode film layer is 1% to 32%.

[0040] Therefore, in the embodiments of the present application, when the mass content of the silicon elements is in the above range, the energy density and the use reliability of the cylindrical battery cell can be improved.

[0041] In a second aspect, the embodiments of the present application further provide a battery, which includes the cylindrical battery cell according to any one of the embodiments of the first aspect of the present application.

[0042] In a third aspect, the embodiments of the present application further provide an electric device, which includes the battery according to any one of the embodiments of the second aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the drawings.

[0044] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application;

[0045] FIG. 2 is an exploded schematic diagram of a battery according to some embodiments of the present application;

[0046] FIG. 3 is an exploded schematic diagram of a battery module shown in FIG. 2;

[0047] FIG. 4 is a structural schematic diagram of a cylindrical battery cell according to some embodiments of the present application;

[0048] FIG. 5 is an exploded schematic diagram of a cylindrical battery cell according to some embodiments of the present application;

[0049] FIG. 6 is a sectional view of a cylindrical battery cell according to some embodiments of the present application;

[0050] Fig. 7 is an enlarged view of the cylindrical battery cell shown in Fig. 6 at A;

[0051] Fig. 8 is a cross-sectional view of a battery cell according to some embodiments of the present application;

[0052] Fig. 9 is a cross-sectional view of a cylindrical battery cell according to other embodiments of the present application;

[0053] Fig. 10 is a cross-sectional view of a cylindrical battery cell according to further embodiments of the present application.

[0054] The accompanying drawings are not necessarily drawn to scale.

[0055] Reference signs are explained as follows:

[0056] X, axial direction; Y, radial direction;

[0057] 1, vehicle; 2, battery; 3, controller; 4, motor; 5, case; 5a, first case portion; 5b, second case portion; 5c, accommodation space; 6, battery module; 7, cylindrical battery cell;

[0058] 10, electrode assembly; 111, first tab; 112, second tab; 12, main body portion; 121, middle region; 122, end region; 122a, end surface; 12a, outer surface;

[0059] 20, housing; 21, case; 211, end wall; 212, side wall; 2121, first portion; 2122, second portion; 212a, outer peripheral surface; 212b, inner surface;

[0060] 22, end cap;

[0061] 30, electrode terminal;

[0062] 40, current collecting member. DETAILED DESCRIPTION

[0063] Hereinafter, embodiments of the cylindrical battery cell, the battery, and the electric device according to the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters that are well known, repeated description of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0064] "RANGES" disclosed herein are defined with both a lower and an upper limit, and a given range is defined with a selected lower limit and a selected upper limit that define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" indicates a shorthand way of describing each and every interger value that is within the range of a to b, wherein a and b are both integers. For example, the numerical range "0-5" indicates that all integers between 0 and 5 are contemplated herein, and "0-5" is merely a shorthand way of describing each and every integer within the range of 0 to 5. In addition, when a parameter is stated to be an integer > 2, it is equivalent to state that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0065] Unless otherwise indicated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0066] Unless otherwise indicated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0067] Unless otherwise indicated, all steps of the present application can be performed in sequence or randomly, and preferably in sequence. For example, a method comprising steps (a) and (b) indicates that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, it is mentioned that the method can further comprise step (c), indicating that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0068] In the present application, the phrase "embodiment" means that the specific features, structures or properties described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor is it independent or alternative to other embodiments.

[0069] In the description of the application, it should be explained that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "attachment" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0070] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the existence of A alone, the existence of A and B together, and the existence of B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0071] In the embodiments of the present application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length, 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 and should not constitute any limitation on the present application.

[0072] "Multiple" appearing in the present application means two or more (including two). In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging the battery cell.

[0073] The battery cell can include, but is not limited to, a lithium ion battery cell, a sodium ion battery cell, a sodium lithium ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium sulfur battery cell, a magnesium ion battery cell, a nickel hydrogen battery cell, a nickel cadmium battery cell, a lead-acid battery cell, etc.

[0074] As an example, the battery cell can be a cylindrical battery cell, which refers to a battery cell whose outer shape is in a cylindrical structure or similar to a cylindrical structure.

[0075] The battery referred to 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.

[0076] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0077] In some embodiments, the battery can be a battery pack, which includes a box body and a battery cell, and the battery cell or the battery module is contained in the box body.

[0078] In some embodiments, the box can be part of a chassis structure of the vehicle. For example, portions of the box can be part of a floor of the vehicle, or portions of the box can be part of cross members and longitudinal members of the vehicle.

[0079] In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0080] The cylindrical battery cell includes an electrode assembly and a housing, and the electrode assembly can swell during the cyclic charging and discharging process, causing extrusion to the housing. The swelling problem exists in almost all parts of the electrode assembly, and the two ends of the electrode assembly in the axial direction can cause extrusion to the middle part of the electrode assembly in the axial direction, increasing the internal stress of the middle part of the electrode assembly, increasing the swelling degree, and increasing the extrusion force of the housing, causing the housing to easily deform or even break at the middle position, affecting the use reliability of the cylindrical battery cell.

[0081] In view of this, the embodiments of the present application provide a cylindrical battery cell, the main body part of the electrode assembly is divided into an end region and a middle region in the axial direction, the distance between the outer surface of the end region and the inner surface of the side wall is smaller, and the distance between the outer surface of the middle region and the inner surface of the side wall of the cylindrical battery cell is larger, leaving a reserved space for the swelling of the electrode assembly, especially the relatively larger reserved space of the middle region of the electrode assembly, which can effectively reduce the extrusion of the electrode assembly to the housing and improve the use reliability of the cylindrical battery cell.

[0082] The cylindrical battery cell described in the embodiments of the present application is suitable for batteries and electric devices using batteries.

[0083] The cylindrical battery cell, the battery and the electric device disclosed in the embodiments of the present application can be used in electric devices using batteries as power sources or various energy storage systems using batteries as energy storage elements. The electric device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric plane toys, etc., and the spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0084] The following embodiments take the vehicle as an example for convenience of description.

[0085] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application.

[0086] As shown in FIG. 1, the vehicle 1 is internally provided with a battery 2, which can be arranged at the bottom, head or tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as an operating power source of the vehicle 1.

[0087] The vehicle 1 can also include a controller 3 and a motor 4, the controller 3 being configured to control the battery 2 to supply power to the motor 4, for example, for the power requirements of the vehicle 1 during start-up, navigation and travel.

[0088] In some embodiments of the present application, the battery 2 can not only serve as a power source for the operation of 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.

[0089] FIG. 2 is an exploded view of a battery according to some embodiments of the present application. As shown in FIG. 2, the battery 2 includes a box body 5 and a cylindrical battery cell (not shown in FIG. 2), the cylindrical battery cell being accommodated in the box body 5.

[0090] The box body 5 is configured to accommodate the cylindrical battery cell, and the box body 5 can have various structures. In some embodiments, the box body 5 can include a first box body part 5a and a second box body part 5b, the first box body part 5a and the second box body part 5b being mutually coverable, and the first box body part 5a and the second box body part 5b together defining an accommodation space 5c for accommodating the cylindrical battery cell. The second box body part 5b can be a hollow structure with one end open, and the first box body part 5a can be a plate-like structure, the first box body part 5a being coverable to the open end of the second box body part 5b to form the box body 5 with the accommodation space 5c. Alternatively, the first box body part 5a and the second box body part 5b can each be a hollow structure with one side open, the open end of the first box body part 5a being coverable to the open end of the second box body part 5b to form the box body 5 with the accommodation space 5c. Of course, the first box body part 5a and the second box body part 5b can have various shapes, such as a cylinder, a cuboid, etc.

[0091] To improve the sealing performance of the first box body part 5a and the second box body part 5b after being connected, a sealing member, such as sealing glue, a sealing ring, etc., can be arranged between the first box body part 5a and the second box body part 5b.

[0092] Suppose the first box body part 5a is coverable to the top of the second box body part 5b, the first box body part 5a can also be referred to as an upper box cover, and the second box body part 5b can also be referred to as a lower box body.

[0093] In the battery 2, the cylindrical battery cell can be one or multiple. If the cylindrical battery cell is multiple, the multiple cylindrical battery cells can be connected in series, in parallel or in a mixed manner. The mixed manner means that the multiple cylindrical battery cells are connected in both series and parallel. The multiple cylindrical battery cells can be directly connected in series, in parallel or in a mixed manner, and then the whole of the multiple cylindrical battery cells is accommodated in the box body 5. Alternatively, the multiple cylindrical battery cells can be first connected in series, in parallel or in a mixed manner to form a battery module 6, and then the multiple battery modules 6 are connected in series, in parallel or in a mixed manner to form a whole, and the whole is accommodated in the box body 5.

[0094] The cylindrical battery cell can be the smallest unit constituting a battery.

[0095] FIG. 3 is a structural schematic diagram of the battery module shown in FIG. 2.

[0096] In some embodiments, as shown in FIG. 3, the cylindrical battery cell 7 is multiple, and the multiple cylindrical battery cells 7 are connected in series or in parallel or in mixed connection to constitute a battery module 6. The multiple battery modules 6 are connected in series or in parallel or in mixed connection to form a whole and are accommodated in a box.

[0097] The multiple cylindrical battery cells 7 in the battery module 6 can be electrically connected through a busbar component to realize parallel connection or series connection or mixed connection of the multiple cylindrical battery cells 7 in the battery module. The busbar component can be one or more, and each busbar component is used to electrically connect at least two cylindrical battery cells.

[0098] FIG. 4 is a structural schematic diagram of a cylindrical battery cell provided in some embodiments of the present application; and FIG. 5 is an exploded schematic diagram of the cylindrical battery cell shown in FIG. 4.

[0099] As shown in FIGS. 4 and 5, in some embodiments, the cylindrical battery cell 7 includes an electrode assembly 10 and a shell 20, and the electrode assembly 10 is accommodated in the shell 20.

[0100] The shell 20 is a cylindrical structure, and the shell 20 includes a shell body 21 which is a cylindrical structure. The shape of the electrode assembly 10 is also a cylindrical structure. The axial direction of the shell 20 is parallel to the axial direction of the electrode assembly 10, and the radial direction of the shell 20 is parallel to the radial direction of the electrode assembly 10.

[0101] In some embodiments, the dimension of the shell 20 along the axial direction is 1.3 to 2.5 times the dimension of the shell 20 along the radial direction, for example, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, or a range composed of any two of the above values. When the shell 20 satisfies the above dimension requirement, the structure of the shell 20 is stable in cooperation with the structural features of the cylindrical battery cell 7 (for example, 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), which can improve the use reliability of the cylindrical battery cell.

[0102] Exemplarily, the shell 20 has an axial dimension of 50mm to 150mm, such as 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm, 150mm, or a range defined by any two of the above values.

[0103] Exemplarily, the shell 20 has a radial dimension of 40mm to 80mm, such as 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, or a range defined by any two of the above values.

[0104] The electrode assembly 10 includes a positive electrode and a negative electrode. During charging and discharging of the cylindrical battery cell 7, active ions (e.g., lithium ions) are inserted into and extracted from the positive electrode and the negative electrode. Optionally, the electrode assembly 10 further includes a separator disposed between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive electrode and the negative electrode, while allowing the active ions to pass through.

[0105] In some embodiments, the positive electrode can be a positive electrode tab, which can include a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0106] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0107] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, titanium, silver surface treated aluminum, or stainless steel, etc. can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can 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 base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0108] 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 can include at least one of the following materials: phosphates, layered transition metal oxides, and modified compounds of each of them; alternatively, the positive electrode active material can include layered transition metal oxides and modified compounds of each of them, which are advantageous in increasing the energy density of the cylindrical battery cell 7. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode film layer of a battery can also be used. These positive electrode active materials can be used alone or in combination of two or more.

[0109] Examples of the phosphates can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (which can also be referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon.

[0110] The layered transition metal oxide includes at least one of a compound of the general formula Li a Ni b Co c M d O e A f , and modified compounds thereof, where 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.

[0111] Examples of the layered transition metal oxide can include, but are not limited to, at least one of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be referred to as NCM 622 ), LiNi0.8 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 modified compounds thereof.

[0112] When the cylindrical battery cell 7 of the embodiments of the present application is a sodium ion battery, the positive electrode active material can include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), Prussian blue type materials.

[0113] As an example, the positive electrode active material for a sodium ion battery can include at least one of 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 type materials, and materials of the 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 at least one of H + , Li + , Na + , K + , and NH4 + , M' is a transition metal cation, which can be at least one of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn, and Y is a halide anion, which can be at least one of F, Cl, and Br.

[0114] 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, such as carbon coating modification, fast ion conductor coating modification, etc.

[0115] The cylindrical battery cell 7 will be accompanied by the deintercalation and consumption of active ions such as Li during the charging and discharging process, and the molar content of Li is different when the cylindrical battery cell 7 is discharged to different states. In the enumeration of the positive electrode active material in the embodiments of the present application, the molar content of Li is the initial state of the material, that is, the state before feeding, and the positive electrode active material is applied to the battery system. After the charging and discharging cycle, the molar content of Li may change.

[0116] In the enumeration of the positive electrode active material in the embodiments of the present application, the molar content of oxygen O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen O to change. In fact, the molar content of oxygen O will appear to be floating.

[0117] In some embodiments, the positive electrode can use a foam metal. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, or foam carbon, etc. When the foam metal is used as the positive electrode, the surface of the foam metal can not be provided with a positive electrode film layer, of course, the positive electrode film layer can also be provided. As an example, the foam metal can also be filled or / and deposited with a lithium source material, a potassium metal or a sodium metal, and the lithium source material is a lithium metal and / or a lithium-rich material.

[0118] In some embodiments, the positive electrode film layer can also optionally include a positive electrode conductive agent. The embodiments of the present application do not have special limitations on the type of 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 content of the positive electrode conductive agent in the positive electrode film layer is ≤5wt%.

[0119] In some embodiments, the positive electrode film layer can also optionally include a positive electrode binder. The embodiments of the present application do not have special limitations on the type of positive electrode binder. As an example, the positive electrode binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylic ester resin. In some embodiments, the mass percentage content of the positive electrode binder in the positive electrode film layer is ≤5wt%.

[0120] 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, the optional conductive agent, the optional binder and any other components in a solvent and stirring uniformly. The solvent can be N-methyl pyrrolidone (NMP), but is not limited thereto.

[0121] In some embodiments, the negative electrode can be a negative electrode tab, which can include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0122] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0123] As an example, the negative electrode current collector can employ a metal foil, a foamed metal, or a composite current collector. For example, as the metal foil, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, or the like formed of carbon, nickel, or titanium, etc. can be employed. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector can include a polymer material base layer 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 base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0124] As an example, the negative electrode active material can employ a negative electrode active material for a cylindrical battery cell 7 known in the art. As an example, the negative electrode active material can include at least one of a carbon material (e.g., the carbon material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon), a silicon-based material, a tin-based material, and lithium titanate, etc. The silicon-based material can include at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can include at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode film layer for a battery can also be used. These negative electrode film layers can be used alone or in combination with two or more.

[0125] In some embodiments, the negative electrode active material includes a silicon element, which can be present in the form of a silicon-based material, e.g., the silicon-based material can include at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The introduction of the silicon element can improve the energy density of the cylindrical battery cell 7.

[0126] In some embodiments, the mass content of silicon element in the negative electrode film layer is 1wt% to 32wt%, optionally 2% to 19%, further optionally 6% to 13%. When the mass content of silicon element is within the above range in the cylindrical battery cell 7 system, the energy density of the cylindrical battery cell 7 can be improved; and the negative electrode film layer will swell in volume during the charging process, which cooperates with the structural characteristics of the cylindrical battery cell 7 (for example, 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), so that the gap between the middle region of the shell 20 and the electrode assembly 10 is larger, which can reserve more sufficient swelling space, reduce the extrusion effect on the shell 20, improve the structural stability of the shell 20, and thus improve the use reliability of the cylindrical battery cell 7.

[0127] In the embodiments of the present application, the mass content of silicon element in the negative electrode film layer is the meaning known in the art, which can be detected by using the devices and methods known in the art, for example, placing the negative electrode sheet in a solvent such as water for soaking, separating the negative electrode active material from the negative electrode current collector, and then filtering to obtain each substance in the negative electrode film layer, which is used as a test sample. The content of silicon element can be obtained by using the inductively coupled plasma-emission spectrometer of ICAP7400 model of Thermo Fisher Scientific Company, USA, and referring to the GB / T30902-2014 standard.

[0128] In some embodiments, the negative electrode film layer can further optionally include a negative electrode conductive agent. The type of negative electrode conductive agent is not particularly limited in the embodiments of the present application. As an example, the negative electrode conductive agent can include at least one of super-conductive carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage content of the negative electrode conductive agent in the negative electrode film layer is ≤5wt%.

[0129] In some embodiments, the negative electrode film layer can further optionally include a negative electrode binder. The type of negative electrode binder is not particularly limited in the embodiments of the present application. As an example, the negative electrode binder can include at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (for example, polyacrylic acid PAA, polymethylacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage content of the negative electrode binder in the negative electrode film layer is ≤5%.

[0130] In some embodiments, the negative electrode film layer can also optionally include other auxiliary agents. As an example, the other auxiliary agents can include thickening agents, such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, and the like. In some embodiments, the mass percentage content of the other auxiliary agents in the negative electrode film layer is ≤ 2 wt%.

[0131] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.

[0132] In some embodiments, the separator includes a separator film. The type of the separator film is not particularly limited in the embodiments of the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be selected.

[0133] The type of the separator film is not particularly limited in the embodiments of the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be selected.

[0134] In some embodiments, the material of the separator film can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0135] In some embodiments, the separator film can include a porous base film and a coating layer provided on at least one side of the porous base film, and the coating layer can include at least one of inorganic particles or organic particles.

[0136] The porous base film can include one or more of polyethylene and polypropylene.

[0137] The inorganic particles have good heat resistance and can improve the overall heat resistance of the separator film. The inorganic particles are substantially not subject to 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 to not undergo oxidation and reduction reactions with alkali metals and / or alkaline earth metals at the nominal voltage of the sodium ion battery.

[0138] 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.

[0139] 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, polyamide-imide, polyimide, copolymer of butyl acrylate and ethyl methacrylate, and mixtures thereof.

[0140] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte.

[0141] During charging and discharging of the battery cell, active ions are inserted and de-inserted between the positive electrode and the negative electrode, and the electrolyte functions to conduct the active ions between the positive electrode and the negative electrode. The type of electrolyte is not particularly limited in the embodiments of the present application and can be selected as desired.

[0142] The electrolyte includes an electrolyte salt and a solvent. The type of electrolyte salt and solvent is not particularly limited and can be selected as desired.

[0143] When the cylindrical battery cell 7 of the embodiments of the present application is a lithium ion battery, the electrolyte salt may, for example, include at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalato borate (LiDFOB), lithium difluorooxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0144] When the cylindrical battery cell 7 of the embodiments of the present application is a sodium ion battery, the electrolyte salt may, for example, include at least one of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bisfluorosulfonylimide (NaFSI), sodium bis-trifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalato borate (NaDFOB), sodium difluorooxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0145] As an example, the solvent can include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl 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), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0146] In some embodiments, the electrolyte can further optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive capable of improving certain performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature performance of the battery, an additive capable of improving low-temperature power performance of the battery, and the like.

[0147] As shown in FIGS. 4 and 5, in some embodiments, the electrode assembly 10 can have a jelly-roll structure or a stacked structure, and optionally, the electrode assembly 10 has a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound to have the jelly-roll structure.

[0148] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be provided, respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets can be alternately stacked.

[0149] In some embodiments, the case 20 includes a housing 21 having an opening and an end cap 22 for closing the opening.

[0150] The housing 21 is a component for fitting the end cap 22 to form an internal cavity of the cylindrical battery cell 7, and the internal cavity formed can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0151] The housing 21 and the end cap 22 can be separate components. As an example, the housing 21 can be provided with an opening, and the internal cavity of the cylindrical battery cell 7 can be formed by fitting the end cap 22 to close the opening.

[0152] The end cap 22 can be connected to the housing 21 by welding, adhesion, clamping, or other means.

[0153] The shell 21 can be open at one end or at both ends. In some examples, the shell 21 can be a structure open at one side, and the end cover 22 is provided as one and covers the shell 21. In other examples, the shell 21 can also be a structure open at both sides, and the end cover 22 is provided as two, and the two end covers 22 cover the two openings of the shell 21 respectively.

[0154] 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 along the axial direction of the cylindrical battery cell 7, and the end cover 22 is sealingly connected to the side wall 212, and the side wall 212 is arranged around the electrode assembly 10.

[0155] In some embodiments, the end wall 211 and the side wall 212 can have the same polarity.

[0156] In some embodiments, the end wall 211 and the side wall 212 can be an integrally formed structure, that is, the shell 21 is an integrally formed member. Of course, the end wall 211 and the side wall 212 can also be two members provided separately and then connected together by welding, riveting, bonding or the like.

[0157] From the appearance of the electrode assembly 10, the electrode assembly 10 includes a main body part 12, a first tab 111 and a second tab 112, the polarities of the first tab 111 and the second tab 112 are opposite, and the first tab 111 and the second tab 112 respectively protrude from the main body part 12. The first tab 111 is a part of the first tab that is not coated with an active material layer, and the second tab 112 is a part of the second tab that is not coated with an active material layer. The first tab 111 and the second tab 112 are used to lead out the current in the main body part 12. The polarities of the first tab and the second tab are opposite, that is, one of the first tab and the second tab is a positive electrode tab, and the other of the first tab and the second tab is a negative electrode tab.

[0158] Taking the first tab 111 as a negative electrode tab and the second tab 112 as a positive electrode tab as an example for description; the part of the negative electrode current collector in the negative electrode tab that is not coated with an active material layer is a negative electrode tab, the active material coated by the negative electrode current collector in the negative electrode tab constitutes a negative electrode film layer, and the negative electrode film layer and the part of the negative electrode current collector coated with the active material are part of the main body part 12. The part of the positive electrode current collector in the positive electrode tab that is not coated with an active material layer is a positive electrode tab, the active material coated by the positive electrode current collector in the positive electrode tab constitutes a positive electrode film layer, and the positive electrode film layer and the part of the positive electrode current collector coated with the active material are part of the main body part 12.

[0159] In some embodiments, the cylindrical battery cell 7 includes a first electrode lead-out part and a second electrode lead-out part, the first electrode lead-out part is electrically connected to the first tab 111, and the second electrode lead-out part is electrically connected to the second tab 112.

[0160] In the axial direction of the main body 12, the first electrode lead-out portion and the second electrode lead-out portion can also be located on both sides of the electrode assembly, or the first electrode lead-out portion and the second electrode lead-out portion are located on the same side of the electrode assembly, for example, the second electrode lead-out portion includes the electrode terminal 30 which is insulated arranged on the end wall 211, and the first electrode lead-out portion is the end wall 211.

[0161] The first tab 111 and the second tab 112 can be extended from the same side of the main body 12, or can be extended from opposite sides respectively.

[0162] The first tab 111 and the second tab 112 can be respectively arranged on both sides of the main body 12 in the axial direction, in other words, the first tab 111 and the second tab 112 are respectively arranged on both ends of the electrode assembly 10 in the axial direction.

[0163] Optionally, the first tab 111 is wound around the central axis of the electrode assembly 10 for multiple turns, and the first tab 111 includes multiple tab layers. After winding is completed, the first tab 111 is generally cylindrical, and a gap is left between adjacent two tab layers. The first tab 111 can be processed in the embodiment of the application to reduce the gap between the tab layers and facilitate the connection of the first tab 111 with other conductive structures. For example, the first tab 111 can be subjected to a rubbing treatment to make the end portion of the first tab 111 away from the main body 12 gather together; the rubbing treatment forms a dense end face at the end of the first tab 111 away from the main body 12, reduces the gap between the tab layers, and facilitates the connection of the first tab 111 with other conductive structures. Alternatively, the gap between the adjacent two tab layers can be filled with a conductive material.

[0164] Optionally, the second tab 112 is wound around the central axis of the electrode assembly 10 for multiple turns, and the second tab 112 includes multiple tab layers. Exemplarily, the second tab 112 is also subjected to a rubbing treatment to reduce the gap between the tab layers of the second tab 112.

[0165] The first tab 111 is electrically connected to the end cover 22. The first tab 111 can be directly electrically connected to the end cover 22, or can be indirectly electrically connected to the end cover 22 through other conductive structures, and the end cover 22 is electrically connected to the end wall 211.

[0166] The second tab 112 is electrically connected to the electrode terminal 30 of the cylindrical battery cell 7, and the electrode terminal 30 is insulated arranged on the end wall 211. The second tab 112 can be directly electrically connected to the electrode terminal 30, or can be indirectly electrically connected to the electrode terminal 30 through other conductive structures.

[0167] In some embodiments, the second tab 112 can be directly connected to the electrode terminal 30, for example, by welding, abutting or other means. Alternatively, the second 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 tab 112 and the electrode terminal 30.

[0168] The electrode terminal 30 is insulated from the end wall 211, and thus the electrode terminal 30 and the end wall 211 can have different polarities and can serve as different output poles.

[0169] The end wall 211 can be provided with an electrode lead-out hole, and the electrode terminal 30 is insulated from the end wall 211 and is mounted in the electrode lead-out hole. The electrode lead-out hole facilitates leading out the electrical energy of the electrode assembly 10 to the outside of the shell 21.

[0170] The central axis of the electrode assembly 10 is a virtual straight line, which can pass through the electrode lead-out hole or be arranged offset from the electrode lead-out hole, which is not limited in the present application.

[0171] The electrode terminal 30 can be fixed to the end wall 211. The electrode terminal 30 can be fixed integrally on the outside of the end wall 211 or can extend into the interior of the shell 20 through the electrode lead-out hole.

[0172] When the first tab 111 is a negative tab and the second tab 112 is a positive tab, the end wall 211 is the negative output pole of the cylindrical battery monomer 7, and the electrode terminal 30 is the positive output pole of the cylindrical battery monomer 7. When the first tab 111 is a positive tab and the second tab 112 is a negative tab, the end wall 211 is the positive output pole of the cylindrical battery monomer 7, and the electrode terminal 30 is the negative output pole of the cylindrical battery monomer 7.

[0173] FIG. 6 is a cross-sectional view of a cylindrical battery monomer according to some embodiments of the present application, FIG. 7 is an enlarged view of the cylindrical battery monomer shown in FIG. 6 at position A, and FIG. 8 is a cross-sectional view of a battery monomer according to some embodiments of the present application.

[0174] As shown in FIGS. 6-8, in some embodiments, the cylindrical battery monomer 7 includes a shell 20 and an electrode assembly 10 contained in the shell 20, the shell 20 includes a side wall 212 arranged around the electrode assembly 10, and the electrode assembly 10 includes a main body portion 12 including a middle region 121 and two end regions 122 arranged along an axis thereof, the middle region 121 being located between the two end regions 122. In the radial direction of the main body portion 12, the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 is greater than the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212.

[0175] The X direction shown in FIGS. 6 and 7 represents the axial direction of the body part 12, i.e., the axial direction of the electrode assembly 10, which is parallel to the axial direction of the shell 20. The Y direction represents the radial direction of the body part 12, i.e., the radial direction of the electrode assembly 10, which is parallel to the radial direction of the shell 20. The X direction is perpendicular to the Y direction.

[0176] During charging of the cylindrical battery cell 7, the body part 12 can expand in volume, so that the body part 12 has a risk of pressing the side wall 212; the internal stress of the body part 12 is substantially the same at each point in the radial direction Y; due to the higher degree of freedom of expansion of the end region 122, the end region 122 of the body part 12 can further press the middle region 121 in the axial direction X, so that the internal stress of the middle region 121 is intensified, the degree of expansion in the radial direction Y is greater, and the risk of the middle region 121 pressing and damaging the side wall 212 is greater. However, the gap between the body part 12 and the side wall 212 in the embodiments of the present application provides expansion space for the body part 12, reduces the risk of the body part 12 pressing the side wall 212, further makes the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 relatively smaller, and makes the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 relatively greater, so as to provide more sufficient expansion space for the middle region 121, effectively reduce the pressing effect of the body part 12 on the side wall 212, and improve the use reliability of the cylindrical battery cell 7.

[0177] In the embodiments of the present application, the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 is greater than the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212, which can be understood as the minimum value of the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 being greater than the maximum value of the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212.

[0178] The inner surface 212b of the side wall 212 is the surface of the side wall 212 facing the body part 12, and the outer surface 12a of the body part 12 can also be understood as the surface of the body part 12 facing the side wall 212. Specifically, for example, the end region 122 includes an end face 122a facing away from the middle region 121, the dimension of the body part 12 in the axial direction X is defined as L, the position of the end face 122a of one of the two end regions 122 is the origin, and the position of the end face 122a of the other end region 122 is L, the distance between the body part 12 and the side wall 212 at L / 3 of the body part 12 is tested, the distance between the outer surface 12a at L / 3 of the body part 12 and the side wall 212 at multiple positions can be tested, and the average value is taken as the distance at this position.

[0179] In FIG. 7, W1 represents the distance between the outer surface at a position in the end region 122 and the inner surface 212b of the side wall 212, and W2 represents the distance between the outer surface at a position in the middle region 121 and the inner surface 212b of the side wall 212, W2 being greater than W1.

[0180] The end region 122 is a structure having a dimension in the axial direction X, and the two end faces 122a, 122a of the main body 12 opposite to each other in the axial direction X are the respective end faces 122a, 122a of the two end regions 122, respectively. The end region 122 is a region between the end faces 122a, 122a and a distance H2 from the end faces 122a, 122a. For example, H2 can be 20 mm, i.e., the dimension of the end region 122 in the axial direction X is 20 mm. In FIG. 8, H2 represents the dimension of the end region 122 in the axial direction X.

[0181] The middle region 121 is a structure having a dimension in the axial direction X, and the middle region 121 is a region between a middle cross section and a distance H1 from the middle cross section, the middle cross section being a cross section containing the center point of the main body 12 on its own axis and being perpendicular to the axis of the main body 12. For example, H1 can be 5 mm, and 2H1 can be 10 mm, i.e., the dimension of the middle region 121 in the axial direction X is 10 mm. In FIG. 8, 2H1 represents the dimension of the middle region 121 in the axial direction X, M represents the axis of the main body 12, and N represents a line at the middle cross section of the main body 12.

[0182] The main body 12 of the electrode assembly 10 includes the end region 122 and the middle region 121, i.e., the main body 12 includes the end region 122, the middle region 121, and the end region 122 arranged in the axial direction X. The end region 122 can be directly connected to the middle region 121, i.e., the main body 12 includes the end region 122, the middle region 121, and the end region 122 arranged in the axial direction X in this order. Of course, a connection region can be included between the end region 122 and the middle region 121, for example, the main body 12 includes the end region 122, a connection region, the middle region 121, a connection region, and the end region 122 arranged in the axial direction X.

[0183] 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 decreases first 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 one-way direction.

[0184] The distance between the outer surface of the central region 121 and the inner surface 212b of the sidewall 212 first decreases and then increases, so that the gap is larger closer to the center position of the central region 121 in the axial X direction, and the reserved expansion space is larger, which can further reduce the risk of the central region 121 squeezing the outer shell 20 and improve the reliability of the cylindrical battery cell 7.

[0185] In this embodiment, the outer shell 20 can be configured in various structural forms to increase the expansion space of the central region 121. The structural forms of the outer shell 20 will be described below.

[0186] As shown in Figures 6 to 8, in some embodiments, the sidewall 212 includes a first portion 2121 and a second portion 2122 disposed along the axial direction X. The first portion 2121 is opposite to the central region 121 in the radial direction Y, and the second portion 2122 protrudes from the surface of the first portion 2121 facing the main body 12 in the radial direction Y, and the second portion 2122 is opposite to the end region 122 in the radial direction Y.

[0187] During the charging process of the cylindrical battery cell 7, the end region 122 expands radially towards the second part 2122, and the middle region 121 expands radially towards the first part 2121, with the middle region 121 expanding to a greater extent. The second part 2122 protrudes radially from the first part 2121, 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, while the distance between the inner surface 212b of the first part 2121 and the outer surface of the middle region 121 is larger. This provides more expansion space for the middle region 121, which helps to reduce the risk of the middle region 121 squeezing the outer casing 20 and improves the reliability of the cylindrical battery cell 7.

[0188] Optionally, the first portion 2121 may further be radially opposite to a portion of the end region 122, and the second portion 2122 may be radially opposite to another portion of the end region 122.

[0189] 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 sidewall 212 tends to increase. 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 unidirectional direction, which is parallel to the direction from the end region 122 to the middle region 121, but opposite in direction.

[0190] The end region 122 is a structure having a size in the axial direction X, the closer to the end face 122a of the end region 122, the higher the expansion degree and the smaller the internal stress; on the contrary, along the axial direction X, as the size increases away from the end face 122a, the internal stress increases, and the expansion degree in the radial direction Y increases, and in the embodiment of the application, the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 is increasing, so that the reserved expansion space is increasing, which is beneficial to reduce the risk of extrusion of the end region 122 to the shell 20 and improve the use reliability of the cylindrical battery cell 7.

[0191] In some embodiments, the second part 2122 can be provided as at least one, for example one or two.

[0192] For example, when the second part 2122 is provided as one, the second part 2122 can be located at any one end of the main body part 12 along the axial direction X.

[0193] Alternatively, for example, when the second part 2122 is provided as two, the two second parts 2122 are respectively located on both sides of the first part 2121 along the axial direction X. When the second part 2122 is provided as two, the two end regions 122 of the main body part 12 are respectively provided with the second part 2122, and through the cooperation of the end region 122 and the second part 2122, it is beneficial to reduce the risk of extrusion of the end region 122 to the shell 20, and at the same time, the second part 2122 can also improve the mechanical strength of the shell 20, improve the anti-deformation ability of the shell 20, and further improve the use reliability of the cylindrical battery cell 7.

[0194] In some embodiments, the size of the first part 2121 along the axial direction X is 0.4 to 0.98 times the size of the side wall 212 along the axial direction X, for example, 0.4 times, 0.45 times, 0.5 times, 0.55 times, 0.6 times, 0.65 times, 0.7 times, 0.75 times, 0.8 times, 0.85 times, 0.9 times, 0.95 times, 0.98 times or a range composed of any of the above values. L1 shown in FIG. 6 is the size of the first part 2121 along the axial direction X, and L0 is the size of the side wall 212 along the axial direction X.

[0195] When the size of the first part 2121 along the axial direction X is in the above range, it can provide more sufficient expansion space for the middle region 121, which is beneficial to further reduce the risk of extrusion of the middle region 121 to the shell 20 and improve the use reliability of the cylindrical battery cell 7.

[0196] 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, meaning that the side wall 212 is not deformed substantially or the first portion 2121 and the second portion 2122 are less deformed during the charging of the cylindrical battery cell 7, or the deformation difference is small, in other words, the expansion of the electrode assembly 10 has little or even no effect on the side wall 212, so that the structural stability of the cylindrical battery cell 7 is improved; in this structure, the side wall 212 is non-uniform in thickness, and the inner surface 212b of the side wall 212 is not flush, so that more sufficient expansion space is reserved for the middle region 121. Of course, in other embodiments, the outer circumferential surface 212a of the side wall 212 can also be an arc surface that protrudes 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.

[0197] FIG. 9 is a cross-sectional view of a cylindrical battery cell according to some embodiments of the present application.

[0198] As shown in FIG. 9, in other embodiments, the inner surface 212b of the side wall 212 is an arc surface, that is, the surface of the side wall 212 facing the electrode assembly 10 is an arc surface and is recessed away from the electrode assembly 10. By providing the arc surface of the side wall 212, more sufficient expansion space is reserved for the middle region 121; specifically, the side wall 212 opposite to the middle region 121 can be recessed relatively deeper, and the side wall 212 opposite to the end region 122 can be recessed relatively shallower.

[0199] For example, the side wall 212 can be uniform in thickness or non-uniform in thickness.

[0200] When the side wall 212 is uniform in thickness, the forming process of the side wall 212 is simpler, and when the electrode assembly 10 exerts a pressing 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 use reliability of the side wall 212. Alternatively, along the radial direction Y, the side wall 212 protrudes away from the electrode assembly 10, and the side wall 212 as a whole has a slightly convex structure. Specifically, the outer circumferential surface 212a of the side wall 212 can be an arc surface that protrudes away from the electrode assembly 10. FIG. 8 shows the structure of the uniform-thickness side wall 212.

[0201] FIG. 10 is a cross-sectional view of a cylindrical battery cell according to some embodiments of the present application.

[0202] As shown in FIG. 10, when the side wall 212 is configured to be non-uniform in 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 decreasing first and then increasing provides more sufficient expansion space for the middle region 121. Specifically, a larger gap can be provided at the position of the middle region 121 to provide more sufficient expansion space.

[0203] 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 has a slightly convex structure, which is easy to provide more expansion space for the middle region 121. Specifically, the outer circumferential surface 212a of the side wall 212 can be a curved surface that protrudes in the direction away from the electrode assembly 10. Of course, when the side wall 212 is configured to be non-uniform in thickness, the outer circumferential surface of the side wall 212 can be a cylindrical surface.

[0204] In the above embodiments of the present application, the test of the spacing is performed when the cylindrical battery cell 7 is in a 0% state of charge (SOC). The test can be performed by using devices and methods known in the art. Specifically, the cylindrical battery cell 7 is discharged at 0.33C to 2.5V and then discharged at 0.1C to 2.5V at 25°C, and the cylindrical battery cell 7 is in a 0% state of charge at this time. The cylindrical battery cell 7 in the 0% state of charge is placed in an X-ray computed tomography scanner (brand: GE, model: Phoenix Nanotom M), and the test is performed in accordance with the ISO 15708:2002 standard. Computed tomography images of the cylindrical battery cell 7 in the axial direction X and the radial direction Y are obtained, and the spacing between the side wall 212 and the main body 12 at different positions is measured according to the images. Thus, the spacing between the middle region 121 and the side wall 212 is measured, and the spacing between the end region 122 and the side wall 212 is measured.

[0205] Principle of the X-ray computed tomography scanner: When an X-ray beam with a certain energy and intensity passes through the cylindrical battery cell 7, a tomography image is obtained by an image reconstruction algorithm according to the attenuation and distribution of the X-ray beam in the detected object. Finally, a three-dimensional image of the sample is obtained by using computer information processing and image reconstruction technology.

[0206] In some embodiments, 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 at 100% state of charge, and is a second middle distance when the cylindrical battery cell 7 is at 0% state of charge; 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.

[0207] The negative active material in the cylindrical battery cell 7 can expand in volume during charging. When the cylindrical battery cell 7 is at 100% SOC, the negative active material expands in volume to a relatively large extent, in which 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 a first middle distance. Correspondingly, when the cylindrical battery cell 7 is at 0% SOC, the negative active material expands in volume to a relatively small extent, in which 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 a second middle distance. When the difference between the first middle distance and the second middle distance is within the above range, the cylindrical battery cell 7 expands in volume to a relatively small extent during charging, which is conducive to improving the structural stability of the cylindrical battery cell 7 and improving the use reliability of the cylindrical battery cell 7.

[0208] Illustratively, the difference between the first middle distance and the second middle distance 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 composed of any two of the above values.

[0209] 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 states of charge. Further, the difference between the first middle distance and the second middle distance can be calculated by measuring multiple distances between multiple positions of the middle region 121 and the side wall 212 at different states of charge, and taking the average of the multiple distances as the difference between the first middle distance and the second middle distance; for example, measuring the distance difference between a first position of the middle region 121 and the side wall 212 at different states of charge as a first distance, measuring the distance difference between a second position of the middle region 121 and the side wall 212 at different states of charge as a second distance, and taking the average of the first distance and the second distance as the difference between the first middle distance and the second middle distance.

[0210] In the embodiments of the present application, the spacing test of the cylindrical battery cell 7 at 100% SOC can be tested by using the devices and methods known in the art. Specifically, the cylindrical battery cell 7 prepared above is charged at 0.33C to 4.25V and then charged at 0.1C to 4.25V at 25°C, at which time the cylindrical battery cell 7 is at 100% SOC. The cylindrical battery cell 7 at 100% SOC is placed in an X-ray computed tomography scanner (brand: GE, model: Phoenix Nanotom M), and tested according to the ISO 15708:2002 standard to obtain the computed tomography images of the cylindrical battery cell 7 in the axial X and radial Y directions. The spacing between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 is measured according to the images, and the spacing between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 is also measured.

[0211] In some embodiments, the spacing between the end region 122 and the inner surface 212b of the side wall 212 in the radial Y direction is a first end spacing when the cylindrical battery cell 7 is at 100% SOC, and is a second end spacing when the cylindrical battery cell 7 is at 0% SOC. The first end spacing is less 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.

[0212] The volume expansion of the negative active material of the cylindrical battery cell 7 is relatively large at 100% SOC, in which case the spacing between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 in the radial Y direction is a first end spacing. Correspondingly, the volume expansion of the negative active material of the cylindrical battery cell 7 is relatively small at 0% SOC, in which case the spacing between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 in the radial Y direction is a second end spacing. 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 7 during charging is relatively small, which is beneficial to improving the structural stability of the cylindrical battery cell 7 and improving the use reliability of the cylindrical battery cell 7.

[0213] For example, the difference between the first end spacing and the second end spacing is less than or equal to 0.05 mm, such as 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 composed of any two of the above values.

[0214] The difference between the first end distance and the second end distance can be calculated by measuring the distance between the same position of the end region 122 and the side wall 212 at different states of charge. 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 end region 122 and the side wall 212 at different states of charge, and averaging the multiple distances as the difference between the first end distance and the second end distance; for example, measuring the distance between a first position of the end region 122 and the side wall 212 at different states of charge as a first distance, measuring the distance between a second position of the end region 122 and the side wall 212 at different states of charge as a second distance, and averaging the first distance and the second distance as the difference between the first end distance and the second end distance.

[0215] In some embodiments, the absolute value of the difference between the first middle distance and the second middle distance is a middle variable, and the absolute value of the difference between the first end distance and the second end distance 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.

[0216] When the absolute value of the difference between the middle variable and the end variable is within the above range, the difference in the volume expansion degree of the end region 122 and the middle region 121 of the cylindrical battery cell 7 during charging is small, so that the difference in the volume expansion degree of the main body 12 as a whole is small, and the local over-pressing of the shell 20 is less likely to occur, and the use reliability of the cylindrical battery cell 7 is significantly improved.

[0217] For example, the absolute value of the difference between the middle variable and the end variable is less than or equal to 0.05 mm, such as 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 composed of any two of the above values.

[0218] As shown in FIG. 9, the material of the side wall 212 can be various, such as the base material of the side wall 212 including metal, for example, the metal including but not limited to copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the base material of the side wall 212 includes steel, for example, stainless steel. The side wall 212 with the above metal material has excellent mechanical strength and is less likely to deform, which can improve the structural stability of the side wall 212 and thus improve the use reliability of the cylindrical battery cell 7. In the embodiments of the present application, the base material of the side wall 212 refers to the material with the largest proportion in the side wall.

[0219] In some embodiments, the base material of the side wall 212 comprises 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 comprises steel, and the thickness of the side wall 212 is 0.3mm to 1.2mm, for example, 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 between any two of the above values. The side wall 212 with the above thickness has excellent mechanical strength and is not easy to deform, which can improve the structural stability of the side wall 212 and thus improve the use reliability of the cylindrical battery cell 7.

[0220] 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 comprises metal, for example, the metal comprises but is not limited to copper, iron, aluminum, steel, aluminum alloy, etc. Alternatively, the base material of the end wall 211 comprises steel, for example, stainless steel. The end wall 211 with the above metal material has excellent mechanical strength and is not easy to deform, which can improve the structural stability of the end wall 211 and thus improve the use reliability of the cylindrical battery cell 7.

[0221] In some embodiments, the base material of the end wall 211 comprises metal, and the thickness of the end wall 211 is 0.3mm to 1.2mm. For example, the base material of the end wall 211 comprises steel, and the thickness of the end wall 211 is 0.3mm to 1.2mm.

[0222] As shown in FIGS. 4-7, as an embodiment of the present application, the cylindrical battery cell 7 comprises a shell 20 and an electrode assembly 10 accommodated in the shell 20, the shell 20 comprises a side wall 212 arranged around the electrode assembly 10; the electrode assembly 10 comprises a main body 12 comprising a middle region 121 and two end regions 122 arranged along an axial direction X thereof, the middle region 121 is located between the two end regions 122; the side wall 212 comprises a first portion 2121 and a second portion 2122 arranged along the axial direction X, the first portion 2121 is opposite to the middle region 121 along a radial direction Y, the second portion 2122 protrudes from a surface of the first portion 2121 along the radial direction Y and faces the main body 12, and the second portion 2122 is opposite to the end regions 122 along the radial direction Y; wherein along the radial direction Y of the main body 12, a distance between an outer surface of the middle region 121 and an inner surface 212b of the side wall 212 is greater than a distance between an outer surface of the end region 122 and the inner surface 212b of the side wall 212. The distance between the inner surface 212b of the first portion 2121 and the outer surface of the middle region 121 is greater, which reserves more expansion space for the middle region 121, is conducive to reducing the risk of the middle region 121 extruding the shell 20, and improves the use reliability of the cylindrical battery cell 7.

[0223] As shown in FIG. 8, as another embodiment of the present application, the cylindrical battery cell 7 comprises a shell 20 and an electrode assembly 10 accommodated in the shell 20, the shell 20 comprises a side wall 212 arranged around the electrode assembly 10; the electrode assembly 10 comprises a main body 12 comprising a middle region 121 and two end regions 122 arranged along an axial direction X thereof, the middle region 121 is located between the two end regions 122; an inner surface 212b of the side wall 212 is a curved surface and is concave towards a direction away from the electrode assembly 10; and the side wall 212 can be arranged with equal thickness; wherein along the radial direction of the main body 12, a distance between an outer surface of the middle region 121 and the inner surface 212b of the side wall 212 is greater than a distance between an outer surface of the end region 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 region 121 is greater, which reserves more expansion space for the middle region 121, is conducive to reducing the risk of the middle region 121 extruding the shell 20, and improves the use reliability of the cylindrical battery cell 7.

[0224] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0225] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for some of the technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A cylindrical battery cell, comprising a housing and an electrode assembly accommodated in the housing, the housing comprising a side wall arranged around the electrode assembly; the electrode assembly comprising a main body portion comprising a middle region and two end regions arranged along an axial direction of the main body portion, the middle region being located between the two end regions; wherein an outer surface of the middle region is spaced apart from an inner surface of the side wall by a larger distance than an outer surface of the end region is spaced apart from the inner surface of the side wall along a radial direction of the main body portion.

2. The cylindrical battery cell of claim 1, wherein, the distance between the outer surface of the middle region and the inner surface of the side wall decreases first and then increases along a direction from the end region to the middle region.

3. The cylindrical battery cell according to claim 1 or 2, wherein the side wall comprises a first portion and a second portion arranged along the axial direction, the first portion being opposite to the middle region along the radial direction, the second portion protruding from the first portion along the radial direction to face a surface of the main body portion, and the second portion being opposite to the end region along the radial direction.

4. The cylindrical battery cell of claim 3, wherein, the distance between the outer surface of the end region and the inner surface of the side wall increases along a direction from the middle region to the end region.

5. The cylindrical battery cell according to claim 3 or 4, wherein, the second portion is arranged in two, and the two second portions are respectively located on two sides of the first portion along the axial direction.

6. The cylindrical battery cell according to any one of claims 3 to 5, wherein, 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 any one of claims 3 to 6, wherein, an outer circumferential surface of the side wall is a cylindrical surface.

8. The cylindrical battery cell according to claim 1 or 2, wherein, the inner surface of the side wall is a curved surface and is concave toward a direction away from the electrode assembly.

9. The cylindrical battery cell of claim 8, wherein, the side wall is arranged with a uniform thickness.

10. The cylindrical battery cell of claim 8, wherein, the thickness of the side wall decreases first and then increases along a direction from one of the end regions to the other end region.

11. The cylindrical battery cell of any one of claims 8 to 10, wherein, the side wall is protruded toward a direction away from the electrode assembly. 12.The cylindrical battery cell of any one of claims 1 to 11, wherein, a 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 100% state of charge; a 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 when the cylindrical battery cell is in a 0% state of charge; wherein the first middle distance is smaller than the second middle distance, and a difference between the first middle distance and the second middle distance is less than or equal to 0.05 mm. 13.The cylindrical battery cell of any one of claims 1 to 12, wherein, a distance between the outer surface of 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 100% state of charge; a distance between the outer surface of the end region and the inner surface of the side wall along the radial direction is a second end distance when the cylindrical battery cell is in a 0% state of charge; wherein the first end distance is smaller than the second end distance, and a difference between the first end distance and the second end distance is less than or equal to 0.05 mm. 14.The cylindrical battery cell of any one of claims 1 to 13, wherein, a first middle distance when the cylindrical battery cell is at 100% state of charge; a second middle distance when the cylindrical battery cell is at 0% state of charge, an absolute value of a difference between the first middle distance and the second middle distance being a middle variable; a first end distance when the cylindrical battery cell is at 100% state of charge; a second end distance when the cylindrical battery cell is at 0% state of charge, an absolute value of a difference between the first end distance and the second end distance being an end variable; wherein an absolute value of a difference between the middle variable and the end variable is less than or equal to 0.05 mm.

15. The cylindrical battery cell of any one of claims 1 to 14, wherein, The base material of the side wall comprises metal, and the thickness of the side wall is 0.3 mm to 1.2 mm.

16. The cylindrical battery cell of any one of claims 1 to 15, wherein, The dimension of the shell along the axial direction is 1.3 times to 2.5 times of the dimension of the shell along the radial direction.

17. The cylindrical battery cell of any one of claims 1 to 16, wherein, The dimension of the shell along the axial direction is 50 mm to 150 mm; and / or The dimension of the shell along the radial direction is 40 mm to 80 mm.

18. The cylindrical battery cell of any one of claims 1 to 17, wherein, The shell comprises a shell body and an end cover, the shell body comprising the side wall and the end wall formed integrally, the end wall and the end cover being opposite along the axial direction, and the end cover being sealingly connected to the side wall.

19. The cylindrical battery cell of claim 18, wherein, The electrode assembly comprises first and second polar opposite tabs, the first and second tabs respectively protruding from the main body portion; The cylindrical battery cell further comprises an electrode terminal insulatively arranged on the end wall, the electrode terminal being electrically connected to the second tab, and the end wall being electrically connected to the first tab.

20. The cylindrical battery cell of any one of claims 1 to 19, wherein, The electrode assembly comprises a negative electrode tab, the negative electrode tab comprising a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector and containing a negative electrode active material, the negative electrode active material comprising silicon element.

21. The cylindrical battery cell of claim 20, wherein, The mass content of the silicon element in the negative electrode film layer is 1% to 32%.

22. A battery comprising the cylindrical battery cell according to any one of claims 1 to 21.

23. An electric device comprising the battery according to claim 22, the battery being configured to provide electric energy.

Images