Battery cells, batteries and power consumption devices

Abstract

This application relates to a battery cell, a battery and a power consumption device, wherein the battery cell includes an electrode assembly and a housing, the electrode assembly includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer installed on at least one side of the negative electrode current collector and containing a negative electrode active material, the housing accommodates the electrode assembly, the housing includes side walls, the side walls are installed surrounding the electrode assembly, the negative electrode active material contains silicon, and the housing has a cylindrical structure. Embodiments of this application can improve the energy density of the battery cell while simultaneously providing the battery cell with excellent reliability in use.

Description

Cross-reference of related applications

[0001] This application claims priority to Chinese patent application 202410536596.0, filed on April 30, 2024, entitled “Battery Cell, Battery and Power Consumption Device,” the entirety of which is incorporated herein by reference. [Technical Field]

[0002] This application relates to the field of rechargeable batteries, and more particularly to battery cells, batteries and power consumption devices. [Background technology]

[0003] Battery cells have characteristics such as high capacity, and are therefore widely used in electronic devices such as mobile phones, laptops, battery cars, electric vehicles, electric airplanes, electric steamships, electric toy cars, electric toy steamships, electric toy airplanes, and power tools.

[0004] As the field of battery cells develops, the demands on battery performance are gradually increasing. This is leading to improvements in the energy density of battery cells, while at the same time deteriorating the reliability of the battery cells in use. [Overview of the Initiative]

[0005] This application provides a battery cell, a battery and a power consumption device, and embodiments of this application can improve the energy density of the battery cell while simultaneously providing the battery cell with excellent reliability in use.

[0006] According to a first aspect, an embodiment of the present application provides a battery cell comprising an electrode assembly and a housing, the electrode assembly comprising a negative electrode plate, the negative electrode plate comprising a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector and containing a negative electrode active material, the housing accommodating the electrode assembly, the housing comprising side walls, the side walls provided surrounding the electrode assembly, wherein the negative electrode active material comprises silicon, and the housing has a cylindrical structure.

[0007] As a result, in the embodiment of this application, the battery cell employs a negative electrode active material containing silicon and uses a cylindrical housing. The electrode assembly is cylindrical in proportion to the cylindrical housing, and during the charging process of the battery cell, the radial expansion force of the electrode assembly is the same in all directions. This uniformly distributes the expansion force of the electrode assembly, weakens the pressing force on the housing, improves the structural stability of the housing, and thereby improves the energy density of the battery cell while simultaneously providing the battery cell with excellent reliability.

[0008] In some embodiments, the mass content of silicon in the negative electrode film layer ranges from 1% to 32%. When the mass content of silicon is within this range, it is advantageous for improving the energy density of the battery cell, which in turn is advantageous for the battery cell to have relatively small volume expansion when engaged with the cylindrical housing, and gives the battery cell excellent reliability in use.

[0009] In some embodiments, the mass content of silicon in the negative electrode film layer ranges from 2% to 19%. When the mass content of silicon is within this range, it engages with the cylindrical housing, resulting in relatively small volume expansion of the battery cell and excellent reliability in use.

[0010] In some embodiments, the mass content of silicon in the negative electrode film layer is between 6% and 13%. When the mass content of silicon is within this range, it is advantageous for the battery cell to engage with the cylindrical housing and have relatively small volume expansion, giving the battery cell excellent reliability in use.

[0011] In some embodiments, the capacitance surface density of the negative electrode plate is 3.2 mAh / cm³. 2 That concludes the explanation. When the capacitance surface density of the negative electrode plate is within the above range, it is advantageous for improving the energy density of the battery cell.

[0012] In some embodiments, the capacitance surface density of the negative electrode plate is 3.3 mAh / cm³. 2From 11.5mAh / cm² 2 Therefore, when the capacitance surface density of the negative electrode plate is within the above range, it is advantageous for improving the energy density of the battery cell.

[0013] In some embodiments, the capacitance surface density of the negative electrode plate is 3.96 mAh / cm³. 2 From 7.56mAh / cm² 2 Therefore, when the capacitance surface density of the negative electrode plate is within the above range, it is advantageous for improving the energy density of the battery cell.

[0014] In some embodiments, the substrate material of the sidewall includes steel, and the thickness of the sidewall is 0.3 mm to 0.9 mm. When the thickness of the sidewall is within the above range, the mechanical strength of the sidewall is relatively high and it is less prone to deformation, which is further advantageous when used in combination with a silicon-containing negative electrode to improve the energy density of the battery cell, while also giving the battery cell excellent reliability in use.

[0015] In some embodiments, the sidewall thickness is between 0.3 mm and 0.55 mm. When the sidewall thickness is within this range, it is used in combination with a silicon-containing negative electrode, which is further advantageous in improving the energy density of the battery cell while also providing the battery cell with excellent reliability.

[0016] In some embodiments, the surface density of the negative electrode film layer is 10.5 mg / cm³. 2 The following is the case: selectively 6 mg / cm³ 2 From 10 mg / cm³ 2 By adjusting the surface density of the negative electrode film layer, the energy density and reliability of the battery cell can be further improved, and this is advantageous for improving cycle performance.

[0017] In some embodiments, the porosity of the negative electrode film layer is 10% or more and less than 100%, selectively between 20% and 40%. By adjusting the porosity of the negative electrode film layer, the energy density and operational reliability of the battery cell can be further improved, and this is advantageous for improving cycle performance.

[0018] In some embodiments, the compaction density of the negative electrode film layer is 1.75 g / cm 3 or less, and selectively 1.4 g / cm 3 to 1.7 g / cm 3 . By adjusting the compaction density of the negative electrode film layer, the energy density and usage reliability of the battery cell can be further improved, and it is advantageous for improving the cycle performance.

[0019] In some embodiments, the electrode assembly includes a main body portion, and the main body portion includes a middle region and two end regions installed along the axial direction of the housing. The middle region is located between the two end regions. Here, along the radial direction of the housing, 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.

[0020] Thereby, the distance between the outer surface of the end region and the inner surface of the side wall in the embodiment of the present application is relatively small, and the distance between the outer surface of the middle region and the inner surface of the side wall is relatively large, so that sufficient expansion space is ensured in advance in the middle region, the pressing action on the side wall of the main body portion is effectively reduced, and the usage reliability of the cylindrical battery cell can be improved.

[0021] In some embodiments, in 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 tends to decrease first and then increase.

[0022] Thereby, the distance between the outer surface of the middle region and the inner surface of the side wall in the embodiment of the present application tends to decrease first and then increase. The closer to the central position in the axial direction of the middle region, the larger the gap becomes, and the larger the pre-ensured expansion space becomes, the pressing action on the housing in the middle region can be effectively further reduced, and the usage reliability of the cylindrical battery cell can be improved.

[0023] In some embodiments, the side wall includes a first portion and a second portion positioned axially, the first portion facing the middle region radially, the second portion projecting radially from the surface of the first portion facing the main body, and the second portion facing the end region radially.

[0024] This results in a larger gap between the inner surface of the first portion and the outer surface of the middle region than in the embodiments of this application, which allows for more expansion space to be pre-secured in the middle region, reduces the risk of the middle region pressing against the housing, and is advantageous in improving the reliability of use of the cylindrical battery cell.

[0025] In some embodiments, the distance between the outer surface of the end region and the inner surface of the side wall tends to increase in the direction from the middle region toward the end region.

[0026] As a result, the distance between the outer surface of the end region and the inner surface of the side wall in the embodiments of this application tends to increase, thereby increasing the pre-secured expansion space, which reduces the risk of the end region pressing against the housing and is advantageous in improving the reliability of use of cylindrical battery cells.

[0027] In some embodiments, two second parts are installed, with each of the two second parts positioned on either side of the first part along its axial direction.

[0028] As a result, in the embodiment of this application, the second portion is installed correspondingly to the two end regions of the main body, and the engagement between the end regions and the second portion is advantageous in reducing the risk of the end regions pressing against the housing. At the same time, the second portion can further improve the mechanical strength of the housing, improve the deformation resistance of the housing, and further improve the reliability of use of the cylindrical battery cell.

[0029] In some embodiments, the axial size of the first portion is 0.4 to 0.98 times the axial size of the side wall.

[0030] This allows for more sufficient expansion space in the middle region when the axial size of the first portion in the embodiment of this application is within the above range, further reducing the risk of the middle region pressing against the housing and is advantageous in improving the reliability of use of the cylindrical battery cell.

[0031] In some embodiments, the outer surface of the side wall is cylindrical. During the charging process of a cylindrical battery cell, the expansion of the electrode assembly has a relatively small, or even no, effect on the side wall, improving the structural stability of the cylindrical battery cell.

[0032] In some embodiments, the inner surface of the side wall is an arcuate surface and is concave toward the direction away from the electrode assembly. By setting the side wall to an arcuate surface, sufficient expansion space is pre-secured in the central region. In some embodiments, the sidewalls are installed at equal thickness. When the electrode assembly applies pressure to the sidewalls, the deformation of the sidewalls is further mitigated, stress concentration problems are less likely to occur, and the reliability of the sidewalls during use can be improved.

[0033] In some embodiments, the thickness of the sidewall tends to decrease first and then increase in the direction from one end region to the other of the two end regions. This tendency for the sidewall thickness to decrease first and then increase ensures that there is more sufficient expansion space in the middle region beforehand.

[0034] In some embodiments, the sidewalls protrude away from the electrode assembly, easily enabling the pre-emption of a larger expansion space in the central region.

[0035] In some embodiments, when the battery cell is 100% charged, the radial distance between the outer surface of the central region and the inner surface of the side wall is the first central distance, and when the battery cell is 0% charged, the radial distance between the outer surface of the central region and the inner surface of the side wall is the second central distance, where the first central distance is smaller than the second central distance, and the difference between the first and second central distances is 0.05 mm or less.

[0036] As a result, when the difference between the first and second mid-section spacings in the embodiments of this application is within the above range, the degree of volume expansion during the charging process of the cylindrical battery cell is relatively small, which is advantageous in improving the structural stability of the cylindrical battery cell and improving the reliability of use of the cylindrical battery cell.

[0037] In some embodiments, when the battery cell is 100% charged, the radial distance between the end region and the inner surface of the side wall is the first end distance, and when the battery cell is 0% charged, the radial distance between the end region and the inner surface of the side wall is the second end distance, where the first end distance is smaller than the second end distance, and the difference between the first and second end distances is 0.05 mm or less.

[0038] As a result, when the difference between the first end spacing and the second end spacing in the embodiment of this application is within the above range, the degree of volume expansion during the charging process of the cylindrical battery cell is relatively small, which is advantageous in improving the structural stability of the cylindrical battery cell and improving the reliability of use of the cylindrical battery cell.

[0039] In some embodiments, when the battery cell is 100% charged, the radial distance between the outer surface of the central region and the inner surface of the side wall is the first central distance, and when the battery cell is 0% charged, the radial distance between the outer surface of the central region and the inner surface of the side wall is the second central distance, and the absolute value of the difference between the first central distance and the second central distance is the central variable, and when the battery cell is 100% charged, the radial distance between the end region and the inner surface of the side wall is the first end distance, and when the battery cell is 0% charged, the radial distance between the end region and the inner surface of the side wall is the second end distance, and the absolute value of the difference between the first end distance and the second end distance is the end variable, where the absolute value of the difference between the central variable and the end variable is 0.05 mm or less.

[0040] As a result, when the absolute value of the difference between the middle and end variables in the embodiment of this application is within the above range, the difference in the degree of volume expansion between the end region and the middle region during the charging process of the cylindrical battery cell is relatively small, the difference in the degree of volume expansion of the entire main body is relatively small, it is less likely to cause localized excessive pressure on the housing, and the reliability of use of the cylindrical battery cell is significantly improved.

[0041] In some embodiments, the axial size of the housing is 1.3 to 2.5 times the radial size of the housing.

[0042] As a result, in the embodiments of this application, when the housing satisfies the above size requirements, 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 results in relatively high structural stability of the housing and can improve the reliability of use of the cylindrical battery cell.

[0043] In some embodiments, the housing has a size along its own axial direction ranging from 50 mm to 150 mm.

[0044] In some embodiments, the housing has a size along its own radial direction ranging from 40 mm to 80 mm.

[0045] In some embodiments, the housing includes a case and an end cap, the case includes integrally formed side walls and end walls, the end walls and end caps facing each other along the axial direction of the housing, and the end caps are sealed to the side walls.

[0046] In some embodiments, the electrode assembly includes a first tab and a second tab with opposite polarity, the first tab and the second tab each protruding from the main body, and the battery cell further includes electrode terminals that are insulated from the end wall, the electrode terminals being electrically connected to the second tab and the end wall being electrically connected to the first tab.

[0047] According to a second aspect, the embodiments of the present application further provide a battery comprising a battery cell of any one embodiment of the first aspect of the present application.

[0048] According to a third aspect, an embodiment of the present application further provides a power consumption device which includes a battery according to any one embodiment of the second aspect of the present application. [Brief explanation of the drawing]

[0049] To more clearly illustrate the technical concept of the embodiments of this application, the following is a brief introduction to the drawings that may be used in the embodiments of this application. It is obvious that the drawings in the following description are only a few of the embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without expending any creative effort. [Figure 1] This is a schematic diagram of the structure of a vehicle according to several embodiments of this application. [Figure 2] This is a schematic diagram of a battery exploded according to some embodiments of this application. [Figure 3] Figure 2 is a schematic diagram of the battery module after disassembly. [Figure 4] This is a schematic diagram of the structure of a battery cell according to several embodiments of this application. [Figure 5] This is a schematic diagram of an exploded battery cell according to some embodiments of this application. [Figure 6] This is a schematic cross-sectional view of a battery cell according to several embodiments of this application. [Figure 7] Figure 6 is a schematic enlarged view of point A in the cylindrical battery cell shown. [Figure 8] This is a schematic cross-sectional view of a battery cell according to several embodiments of this application. [Figure 9] This is a schematic cross-sectional view of a battery cell according to some other embodiments of this application. [Figure 10] These are schematic cross-sectional views of battery cells according to several other embodiments of this application. The drawings are not necessarily drawn to actual scale. [Modes for carrying out the invention]

[0050] The following describes in detail embodiments specifically disclosing the battery cell, battery and power consumption device of this application, with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and repeated explanations of structures that are actually the same may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0051] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the limit value, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 can also be assumed. Furthermore, if 1 and 2 are listed as the minimum range values ​​and 3, 4, and 5 are listed as the maximum range values, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “ab” represents an abbreviation for any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply a shortened representation of combinations of these numbers. Also, expressing a parameter as an integer ≥ 2 is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0052] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0053] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0054] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, if a method mentioned may further include step (c), it means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0055] The “Examples” as used in this application mean that certain features, structures, or characteristics described in conjunction with the Examples may be included in at least one Example of this application. The occurrence of this phrase in each location in the specification does not necessarily refer to the same Example, nor does it mean that each Example is mutually exclusive or alternative to the others.

[0056] In the description of this application, unless otherwise specifically defined or limited, the terms “attachment,” “connection,” “connection,” and “installation” should be understood in a broad sense. For example, a fixed connection may be a detachable connection, an integral connection, a direct connection, an indirect connection via an intermediate medium, or internal communication between two elements. A person skilled in the art will be able to understand the specific meaning of these terms in this application depending on the specific circumstances.

[0057] In this application, the terms "and / or" simply describe a relationship between related objects, indicating that three relationships are possible. For example, A and / or B may represent three cases: A alone, a combination of A and B, or B alone. In this application, the character " / " generally indicates that the preceding and succeeding related objects are in an "or" relationship.

[0058] In the embodiments of this application, the same reference numerals indicate the same component, and for the sake of brevity, detailed descriptions of the same component are omitted in different embodiments. It should be understood that the dimensions such as thickness, aspect ratio of various components in the embodiments of this application shown in the drawings, and the dimensions such as thickness, aspect ratio of the overall assembly device, are illustrative only and do not constitute any limitation of this application.

[0059] In this application, "multiple" refers to two or more (including two). In the embodiments of this application, the battery cell may be a secondary battery, which is a battery cell that can be used continuously by activating the active material through a charging method after the battery cell has been discharged.

[0060] Battery cells may include, but are not limited to, lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium-sulfur battery cells, magnesium-ion battery cells, nickel-metal hydride battery cells, nickel-cadmium battery cells, lead-acid battery cells, etc.

[0061] For example, a battery cell may be a cylindrical battery cell, and a cylindrical battery cell refers to a battery cell whose external shape is cylindrical or similar to a cylindrical structure.

[0062] The batteries referred to in the embodiments of this application refer to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0063] In some embodiments, the battery may be a battery module, and if there are multiple battery cells, the multiple battery cells are arranged and fixed to form a single battery module.

[0064] In some embodiments, the battery may be a battery pack, which includes a housing and battery cells, and the battery cells or battery modules are housed within the housing.

[0065] In some embodiments, the housing can be part of the vehicle's chassis structure. For example, the housing may be part of at least the vehicle's floor, or it may be part of at least the vehicle's cross members and side members.

[0066] In some embodiments, the battery may be an energy storage device. The energy storage device may include an energy storage container, an energy storage electrical cabinet, and the like.

[0067] With the advancement of the battery field, the demand for higher energy density in batteries is gradually increasing. Compared to carbon materials, silicon has a relatively higher theoretical specific capacity, and adopting a silicon-containing negative electrode is undoubtedly an effective way to improve energy density. However, during the charging process of battery cells, silicon expands in volume to a relatively large degree, which can deform the battery cell housing and potentially cause it to rupture. This limits the application of silicon and results in relatively low reliability of battery cells.

[0068] In view of this, the embodiment of the present application provides a battery cell which employs a negative electrode active material containing silicon and uses a cylindrical housing. The electrode assembly is cylindrical in shape and, during the charging process of the battery cell, the radial expansion force of the electrode assembly is the same in all directions. This uniformly distributes the expansion force of the electrode assembly, weakens the pressing force on the housing, improves the structural stability of the housing, thereby improving the energy density of the battery cell and providing the battery cell with excellent reliability in use.

[0069] The battery cells described in the embodiments of this application are applicable to batteries and power consumption devices that use batteries.

[0070] Figure 1 is a schematic diagram of the structure of a vehicle according to some embodiments of this application.

[0071] As shown in Figure 1, a battery 2 is installed inside the vehicle 1, and the battery 2 may be installed at the bottom, front, or rear of the vehicle 1. The battery 2 may be used to power the vehicle 1, for example, the battery 2 may be used as the operating power source for the vehicle 1.

[0072] Vehicle 1 may further include a controller 3 and a motor 4, the controller 3 being used to control the battery 2 to supply power to the motor 4, for example, to meet the power consumption requirements for starting, navigating, and driving Vehicle 1.

[0073] In some embodiments of this application, the battery 2 can be used not only as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, providing driving power to the vehicle 1 in place of or in place of gasoline or natural gas.

[0074] Figure 2 is a schematic exploded view of a battery according to some embodiments of the present application. As shown in Figure 2, the battery 2 includes a housing 5 and a cylindrical battery cell (not shown in Figure 2), the cylindrical battery cell being housed within the housing 5.

[0075] The housing 5 is used to house cylindrical battery cells, and the housing 5 may have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, the first housing portion 5a and the second housing portion 5b overlapping each other, and the first housing portion 5a and the second housing portion 5b together define a housing space 5c for housing cylindrical battery cells. The second housing portion 5b may be a hollow structure with one end open, the first housing portion 5a is a plate-like structure, the first housing portion 5a is placed over the open side of the second housing portion 5b to form a housing 5 having a housing space 5c, and both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, the open side of the first housing portion 5a is placed over the open side of the second housing portion 5b to form a housing 5 having a housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b may have various shapes, such as a cylinder or a rectangular parallelepiped.

[0076] To improve the sealing performance after connecting the first housing portion 5a and the second housing portion 5b, a sealing material may be installed between the first housing portion 5a and the second housing portion 5b, such as a sealant or a sealing ring.

[0077] Assuming that the first housing portion 5a is placed over the top of the second housing portion 5b, the first housing portion 5a is also called the upper housing lid, and the second housing portion 5b is also called the lower housing.

[0078] In battery 2, there may be one cylindrical battery cell or multiple cylindrical battery cells. When there are multiple cylindrical battery cells, the multiple cylindrical battery cells may be connected in series, in parallel, or in series-parallel connection, where series-parallel connection means that there are both series and parallel connections among the multiple cylindrical battery cells. Multiple cylindrical battery cells may be directly connected in series, in parallel, or in series-parallel connection and the entire assembly of multiple cylindrical battery cells may be housed in the housing 5. Of course, multiple cylindrical battery cells may first be connected in series, in parallel, or in series-parallel connection to form a battery module 6, and then the multiple battery modules 6 may be connected in series, in parallel, or in series-parallel connection to form a single unit, which may be housed in the housing 5.

[0079] A cylindrical battery cell may be the smallest unit that makes up a battery.

[0080] Figure 3 is a schematic diagram of the battery module structure shown in Figure 2.

[0081] In some embodiments, as shown in Figure 3, there are multiple battery cells 7, and these multiple battery cells 7 are first connected in series, in parallel, or in series-parallel to form a battery module 6. The multiple battery modules 6 are further connected in series, in parallel, or in series-parallel to form a single unit, which is then housed in a housing.

[0082] Multiple battery cells 7 in the battery module 6 are electrically connected via busbar members to achieve parallel, series, or series-parallel connection of the multiple battery cells 7 in the battery module. There may be one or more busbar members, and each busbar member is used to electrically connect at least two cylindrical battery cells.

[0083] Figure 4 is a schematic diagram of the structure of a cylindrical battery cell according to some embodiments of this application, and Figure 5 is an exploded schematic diagram of the cylindrical battery cell shown in Figure 4.

[0084] As shown in Figures 4 and 5, in some embodiments, the battery cell 7 includes an electrode assembly 10 and a housing 20, the electrode assembly 10 being housed within the housing 20.

[0085] The housing 20 has a cylindrical structure, and the housing 20 includes a case 21, which has a cylindrical structure, and the corresponding electrode assembly 10 also has a cylindrical shape. The axial direction of the housing 20 is parallel to the axial direction of the electrode assembly 10, and the radial direction of the housing 20 is parallel to the radial direction of the electrode assembly 10.

[0086] In some embodiments, the axial size of the housing 20 is 1.3 to 2.5 times the radial size of the housing 20, for example, in the range of 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, or any two of the above values. When the housing 20 meets the above size requirements, it is used in combination with a silicon-containing negative electrode plate in the battery cell 7, and the housing 20 can effectively restrain the electrode assembly 10, reducing the overall volume expansion of the battery cell 7 and improving the reliability of the cylindrical battery cell.

[0087] For example, the axial size of the housing 20 is from 50 mm to 150 mm, and is a range consisting of, for example, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, 150 mm, or any two of the above values.

[0088] For example, the radial size of the housing 20 is in the range of 40 mm to 80 mm, for example, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, or any two of the above values.

[0089] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charging and discharging process of the battery cell 7, active ions (e.g., lithium ions) intercept and deintercept by moving back and forth between the positive and negative electrodes. Selectively, the electrode assembly 10 further includes a separator member placed between the positive and negative electrodes, which reduces the risk of short circuits between the positive and negative electrodes and allows active ions to pass through.

[0090] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charging and discharging process of the battery cell 7, active ions (e.g., lithium ions) intercept and deintercept by moving back and forth between the positive and negative electrodes. Selectively, the electrode assembly 10 further includes a separator member placed between the positive and negative electrodes, which reduces the risk of short circuits between the positive and negative electrodes and allows active ions to pass through.

[0091] In some embodiments, the positive electrode may be a positive electrode plate, and the positive electrode plate may include a positive electrode current collector and a positive electrode film layer placed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0092] For example, a positive electrode current collector has two opposing surfaces in the direction of its own thickness, and the positive electrode film layer is installed on one or both of the two opposing surfaces of the positive electrode current collector.

[0093] For example, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, the metal foil may be stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, titanium, silver-surface-treated aluminum or stainless steel. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene).

[0094] For example, when the battery cell 7 of the embodiment of the present application is a lithium-ion battery, the cathode active material may include at least one of phosphates, layered transition metal oxides, and their respective modified compounds. Optionally, the cathode active material may include layered transition metal oxides and their respective modified compounds, which is advantageous for improving the energy density of the battery cell 7. However, the present application is not limited to these materials, and other conventional materials that can be used as the battery cathode film layer may also be used. These cathode active materials may be used alone or in combination of two or more.

[0095] Examples of phosphates may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0096] The layered transition metal oxide includes at least one of a compound with the general formula Li a Ni b Co c M d O e A f and its modified compounds. 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.

[0097] Examples of layered transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn1 / 3 O2(NCM 333 (It can also be abbreviated as LiNi) 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (It can also be abbreviated as LiNi) 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (It can also be abbreviated as LiNi) 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (It can also be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (This can also be abbreviated as LiNi)), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.80 Co 0.15 Al 0.05 It may contain, but is not limited to, at least one of O2 and its modified compounds.

[0098] If the battery cell 7 of the embodiment of this application is a sodium-ion battery, the positive electrode active material may include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanionic materials (e.g., phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue-based materials.

[0099] For example, the positive electrode active materials used in sodium-ion batteries are NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and 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-based materials, general formula is X p M' q (PO4) r O xY 3-x It may contain at least one of the materials that are General formula X p M' q (PO4) r O x Y 3-x In 0 <p≦4、0<q≦2、1≦r≦3、0≦x≦2であり、Xは、H + Li + kaNa + , K + and NH4 + It contains at least one of the following, where M' is a transition metal cation, selectively at least one of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn, and Y is a halogen anion, selectively at least one of F, Cl, and Br.

[0100] In the embodiments of this application, the modified compounds for each of the above-mentioned positive electrode active materials may be subjected to doping modification and / or surface coating modification of the positive electrode active material, for example, carbon coating modification, high-speed ion conductor coating modification, etc.

[0101] The battery cell 7 undergoes desorption and consumption of active ions, such as Li, during the charge-discharge process, and the molar content of Li differs when the battery cell 7 is discharged to different states. In the enumeration of positive electrode active materials in the embodiments of this application, the molar content of Li is the initial state of the material, i.e., the state before insertion, and the molar content of Li may change as the positive electrode active material is applied to a battery system and undergoes charge-discharge cycles.

[0102] In the enumeration of positive electrode active materials in the embodiments of this application, the molar content of oxygen (O) is only a theoretical value, and lattice oxygen release causes a change in the molar content of oxygen (O), resulting in actual fluctuations in the molar content of oxygen (O).

[0103] In some embodiments, the positive electrode may be made of foamed metal. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon. When foamed metal is used as the positive electrode, a positive electrode film layer may or may not be placed on the surface of the foamed metal. For example, a lithium source material, potassium metal, or sodium metal may be filled and / or deposited within the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0104] In some embodiments, the cathode film layer further selectively contains a cathode conductive agent. The embodiments of this application are not particularly limited to the type of cathode conductive agent, and as an example, the cathode 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 cathode conductive agent in the cathode film layer is ≤5 wt%.

[0105] In some embodiments, the positive electrode film layer further selectively includes a positive electrode adhesive. The embodiments of this application are not particularly limited to the type of positive electrode adhesive, and for example, the positive electrode adhesive may 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 acrylate resins. In some embodiments, the mass percentage content of the positive electrode adhesive in the positive electrode film layer is ≤5 wt%.

[0106] The positive electrode film layer is generally obtained by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, a selective conductive agent, a selective adhesive, and any other components in a solvent and stirring them uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

[0107] In some embodiments, the negative electrode may be a negative electrode plate, and the negative electrode plate may include a negative electrode current collector and a negative electrode film layer placed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0108] For example, a negative electrode current collector has two opposing surfaces in the direction of its own thickness, and the negative electrode film layer is installed on one or both of the two opposing surfaces of the negative electrode current collector.

[0109] For example, the negative electrode current collector may be a metal foil sheet, foamed metal, or a composite current collector. For example, as the metal foil sheet, silver-surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium may be used. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may 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 (for example, a base material such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene).

[0110] For example, the negative electrode active material can be a negative electrode active material used in battery cells 7 known in the art. For example, the negative electrode active material may include at least one of the following materials: carbon material (for example, the carbon material includes at least one of artificial graphite, natural graphite, soft carbon, and hard carbon), silicon-based material, tin-based material, and lithium titanate. The silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode film layers may be used. These negative electrode film layers may be used individually or in combination of two or more.

[0111] In some embodiments, the negative electrode film layer further selectively contains a negative electrode conductive agent. The embodiments of this application are not particularly limited to the type of negative electrode conductive agent, and for example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage content of the negative electrode conductive agent in the negative electrode film layer is ≤5 wt%.

[0112] In some embodiments, the negative electrode film layer further selectively includes a negative electrode adhesive. The embodiments of this application are not particularly limited to the type of negative electrode adhesive, and as an example, the negative electrode adhesive may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic acid resin (e.g., polyacrylate PAA, polymethacrylate 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 adhesive in the negative electrode film layer is ≤5%.

[0113] In some embodiments, the negative electrode film layer may further selectively contain other additives. For example, the other additives may include thickeners such as sodium carboxymethylcellulose (CMC-Na), PTC thermistor materials, etc. In some embodiments, the mass percentage content of the other additives in the negative electrode film layer is ≤2 wt%.

[0114] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0115] In some embodiments, the separator member includes a separator. This application does not particularly limit the type of separator, and any known porous structure separator with excellent chemical and mechanical stability can be arbitrarily selected and used.

[0116] The embodiments of this application do not particularly limit the type of separator, and any known porous structure separator with excellent chemical and mechanical stability can be arbitrarily selected and used.

[0117] In some embodiments, the separator material may include one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0118] In some embodiments, the separator may include a porous base film and a coating placed on at least one side of the porous base film, the coating may include at least one of inorganic particles or organic particles.

[0119] The porous base film may contain one or more of polyethylene and polypropylene.

[0120] Inorganic particles have good heat resistance and can improve the overall heat resistance of the separator. Within the operating voltage range of the sodium-ion battery, the inorganic particles basically do not undergo oxidation and reduction reactions with metal dendrites; in other words, the inorganic particles are configured not to undergo oxidation and reduction reactions with alkali metals and / or alkaline earth metals at the nominal voltage of the sodium-ion battery.

[0121] In some examples, the inorganic particles include one or more of the following: 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.

[0122] In some embodiments, the organic particles include at least one of the following: 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.

[0123] In some embodiments, the battery cell 7 further includes an electrolyte.

[0124] During the charging and discharging process of a battery cell, active ions move back and forth between the positive and negative electrodes, undergoing intercalation and deintercalation, while the electrolyte plays a role in conducting these active ions between the positive and negative electrodes. The embodiments of this application are not particularly limited to the type of electrolyte and can be selected according to actual needs.

[0125] The electrolyte solution contains an electrolyte salt and a solvent. The types of electrolyte salt and solvent are not specifically limited and can be selected according to actual needs.

[0126] The electrolyte solution comprises an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not specifically limited and can be selected according to actual needs.

[0127] If the battery cell 7 of the embodiment of this 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 bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP), but is not limited to these.

[0128] If the battery cell 7 of the embodiment of this 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 bistrifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorobis(oxalato)phosphate (NaDFOP), and sodium tetrafluoro(oxalato)phosphate (NaTFOP), but is not limited to these.

[0129] For example, the solvent may include, but is not limited to, at least one of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0130] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may further include additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, additives that improve the battery's high-temperature performance, and additives that improve the battery's low-temperature output performance.

[0131] As shown in Figures 4 and 5, in some embodiments, the electrode assembly 10 may be a wound structure or a laminated structure, and selectively, the electrode assembly 10 is a wound structure. The positive electrode plate and the negative electrode plate are wound in a wound structure.

[0132] For example, multiple positive and negative electrode plates can be installed, and these multiple positive and negative electrode plates are stacked alternately.

[0133] In some embodiments, the housing 20 includes a case 21 and an end cap 22, the case 21 having an opening, and the end cap 22 being used to cover the opening.

[0134] The case 21 is a component that fits onto the end cap 22 to form an internal cavity of the battery cell 7, and the formed internal cavity may be used to house the electrode assembly 10, electrolyte, and other components.

[0135] The case 21 and the end cap 22 may be separate components. For example, an opening may be provided on the case 21, and the end cap 22 covers the opening to form the internal cavity of the battery cell 7.

[0136] The end cap 22 is connected to the case 21 by welding, bonding, locking, or other means.

[0137] The case 21 may have an open end or both ends. In some examples, the case 21 may have an open structure on one side, with one end cap 22 installed and covering the case 21. In some other examples, the case 21 may have an open structure on both sides, with two end caps 22 installed, each covering one of the two openings of the case 21.

[0138] In some embodiments, the case 21 includes a side wall 212 and an end wall 211 connected to the side wall 212, the end wall 211 and the end cap 22 facing each other along the axial direction of the battery cell 7, the end cap 22 being sealed to the side wall 212, and the side wall 212 being installed surrounding the electrode assembly 10.

[0139] In some embodiments, the end wall 211 and the side wall 212 may have the same polarity.

[0140] In some embodiments, the end wall 211 and the side wall 212 may be integrally formed structures, i.e., the case 21 is an integrally formed member. Of course, the end wall 211 and the side wall 212 may be two separate members that are subsequently joined together by methods such as welding, riveting, or bonding.

[0141] From an external perspective, the electrode assembly 10 includes a main body 12, a first tab 111, and a second tab 112, the polarities of the first tab 111 and the second tab 112 being opposite, and the first tab 111 and the second tab 112 each protruding from the main body 12. The first tab 111 is the portion of the first electrode plate whose active material layer is not covered, and the second tab 112 is the portion of the second electrode plate whose active material layer is not covered. The first tab 111 and the second tab 112 are used to draw current from within the main body 12. The polarities of the first and second electrodes are opposite; in other words, one of the first and second electrodes is the positive electrode plate, and the other of the first and second electrodes is the negative electrode plate.

[0142] As an example, the first tab 111 is the negative electrode tab and the second tab 112 is the positive electrode tab. The portion of the negative electrode current collector on the negative electrode plate that is not covered with an active material layer is the negative electrode tab, the active material covered on the negative electrode current collector on the negative electrode plate constitutes the negative electrode film layer, and the portion of the negative electrode current collector covered with the negative electrode film layer and active material is part of the main body 12. The portion of the positive electrode current collector on the positive electrode plate that is not covered with an active material layer is the positive electrode tab, the active material covered on the positive electrode current collector on the positive electrode plate constitutes the positive electrode film layer, and the portion of the positive electrode current collector covered with the positive electrode film layer and active material is part of the main body 12.

[0143] In some embodiments, the battery cell 7 includes a first electrode lead and a second electrode lead, the first electrode lead being electrically connected to a first tab 111 and the second electrode lead being electrically connected to a second tab 112.

[0144] In the axial direction of the main body 12, the first electrode lead-out section and the second electrode lead-out section may be located on both sides of the electrode assembly, or the first electrode lead-out section and the second electrode lead-out section may be located on the same side of the electrode assembly, for example, the second electrode lead-out section may include an electrode terminal 30 installed insulated from the end wall 211, and the first electrode lead-out section may be the end wall 211.

[0145] The first tab 111 and the second tab 112 may extend from the same side of the main body 12, or they may extend from opposite sides.

[0146] The first tab 111 and the second tab 112 may be provided on both sides along the axial direction of the main body 12, in other words, the first tab 111 and the second tab 112 may be provided at both ends along the axial direction of the electrode assembly 10.

[0147] Selectively, the first tab 111 is wound multiple times around the central axis of the electrode assembly 10, and the first tab 111 includes multiple wound tab layers. After the winding is complete, the first tab 111 is substantially columnar, with gaps remaining between two adjacent tab layers. Embodiments of the present application may perform a treatment on the first tab 111 to reduce the gaps between the tab layers and facilitate connection between the first tab 111 and other conductive structures. For example, embodiments of the present application may perform a planarization treatment on the first tab 111 to bring together the ends of the first tab 111 away from the body 12, the planarization treatment forming a dense end face at one end of the first tab 111 away from the body 12, reducing the gaps between the tab layers and facilitating connection between the first tab 111 and other conductive structures. Alternatively, the embodiments of this application may reduce the gap between the tab layers by filling the space between two adjacent tab layers with a conductive material.

[0148] Selectively, the second tab 112 is wound multiple times around the central axis of the electrode assembly 10, and the second tab 112 includes multiple wound tab layers. Exemplarily, the second tab 112 is also planarized to reduce the gaps between the tab layers of the second tab 112.

[0149] The first tab 111 is electrically connected to the end cap 22. The first tab 111 may be electrically connected directly to the end cap 22, or it may be electrically connected indirectly to the end cap 22 via another conductive structure, and the end cap 22 is electrically connected to the end wall 211.

[0150] The second tab 112 is electrically connected to the electrode terminal 30 of the battery cell 7, and the electrode terminal 30 is installed insulated from the end wall 211. The second tab 112 may be directly electrically connected to the electrode terminal 30, or it may be indirectly electrically connected to the electrode terminal 30 via another conductive structure.

[0151] In some embodiments, the second tab 112 may be directly connected to the electrode terminal 30, or it may be connected to the electrode terminal 30 by, for example, welding, contact, or other means. Alternatively, the electrical connection between the second tab 112 and the electrode terminal 30 may be achieved by indirectly connecting the second tab 112 to the electrode terminal 30 via another conductive member (e.g., a current collector 40).

[0152] The electrode terminal 30 is installed insulated from the end wall 211, and therefore the electrode terminal 30 and the end wall 211 may have different polarities, and the electrode terminal 30 and the end wall 211 may be different output poles.

[0153] Electrode lead-out holes may be provided in the end wall 211, and the electrode terminals 30 are installed insulated from the end wall 211 and attached to the electrode lead-out holes, which facilitate the extraction of electrical energy from the electrode assembly 10 to the outside of the case 21.

[0154] The central axis of the electrode assembly 10 is a virtual straight line, and the central axis of the electrode assembly 10 may pass through the electrode extraction hole or be positioned offset from the electrode extraction hole, and is not limited in this application.

[0155] The electrode terminal 30 may be fixed to the end wall 211. The electrode terminal 30 may be entirely fixed to the outside of the end wall 211, or it may be inserted into the housing 20 through the electrode lead-out hole.

[0156] When the first tab 111 is the negative electrode tab and the second tab 112 is the positive electrode tab, the end wall 211 is the negative output electrode of the battery cell 7, and the electrode terminal 30 is the positive output electrode of the battery cell 7. When the first tab 111 is the positive electrode tab and the second tab 112 is the negative electrode tab, the end wall 211 is the positive output electrode of the battery cell 7, and the electrode terminal 30 is the negative output electrode of the battery cell 7.

[0157] In some embodiments, the battery cell 7 includes an electrode assembly 10 and a housing 20, the electrode assembly 10 including a negative electrode plate, the negative electrode plate including a negative electrode current collector and a negative electrode film layer installed on at least one side of the negative electrode current collector and containing a negative electrode active material, the housing 20 housing the electrode assembly 10, the housing 20 including side walls 212, the side walls 212 installed surrounding the electrode assembly 10, where the negative electrode active material includes the element silicon, and the housing 20 has a cylindrical structure.

[0158] This battery cell 7 employs a negative electrode active material containing silicon and uses a cylindrical housing 20. The electrode assembly 10 is cylindrical in shape, and during the charging process of the battery cell 7, the radial expansion force of the electrode assembly 10 is the same in all directions. This uniformly distributes the expansion force of the electrode assembly 10, weakens the pressing force on the housing 20, improves the structural stability of the housing 20, and thereby improves the energy density of the battery cell 7 while simultaneously providing the battery cell 7 with excellent reliability.

[0159] In some embodiments, the mass content of silicon in the negative electrode film layer is 1% to 32%, selectively 2% to 19%, and even more selectively 6% to 13%. When the mass content of silicon is within the above range, it is advantageous for improving the energy density of the battery cell 7, which in turn is advantageous for the battery cell 7 to have relatively small volume expansion when engaged with the cylindrical housing 20, and gives the battery cell 7 excellent reliability in use.

[0160] For example, the mass content of silicon in the negative electrode film layer may be in the range of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, or any two of the above values.

[0161] In some embodiments, the negative electrode active material contains silicon, which may be present in the form of a silicon-based material, for example, the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The introduction of silicon can improve the energy density of the battery cell 7.

[0162] In the embodiments of this application, the mass content of silicon in the negative electrode film layer is as known in the art and can be detected using instruments and methods known in the art. For example, the negative electrode plate can be immersed in a solvent, such as water, to separate the negative electrode active material and the negative electrode current collector, and the materials in the negative electrode film layer can be obtained by suction filtration, which can then be used as a test sample. The silicon content of the test sample can be determined using an inductively coupled plasma-atomography spectrometer, model ICAP7400, from Thermo Fisher Scientific, USA, with reference to the GB / T30902-2014 standard.

[0163] In some embodiments, the capacitance surface density of the negative electrode plate is 3.2 mAh / cm² or higher, and selectively 3.3 mAh / cm². 2 From 11.5mAh / cm² 2 Furthermore, it selectively produces 3.96mAh / cm². 2 From 7.56mAh / cm² 2 Therefore, when the capacitance surface density of the negative electrode plate is within the above range, it is advantageous for improving the energy density of the battery cell 7.

[0164] For example, the capacitance surface density of the negative electrode plate is 3.2 mAh / cm³. 2 , 3.3mAh / cm²2 、3.33 mAh / cm 2 、3.5 mAh / cm 2 、3.8 mAh / cm 2 、3.9 mAh / cm 2 、4 mAh / cm 2 、4.2 mAh / cm 2 、4.5 mAh / cm 2 、4.8 mAh / cm 2 、4.9 mAh / cm 2 、5 mAh / cm 2 、5.2 mAh / cm 2 、5.5 mAh / cm 2 、5.8 mAh / cm 2 、6 mAh / cm 2 、6.2 mAh / cm 2 、6.5 mAh / cm 2 、6.8 mAh / cm 2 、7 mAh / cm 2 、7.5 mAh / cm 2 、8 mAh / cm 2 、8.5 mAh / cm 2 、9 mAh / cm 2 、9.5 mAh / cm 2 、10 mAh / cm 2 、10.5 mAh / cm 2 、11 mAh / cm 2 、11.5 mAh / cm 2 Or it may be a range consisting of any two of the above numerical values.

[0165] The material of the housing 20 may be of multiple types. For example, the base material of the housing 20 includes, but is not limited to, copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the base material of the housing 20 includes steel such as stainless steel. Exemplarily, the base material of the case includes steel such as stainless steel. The case includes a side wall 212 and an end wall 211. In each embodiment of the present application, the base material of the housing 20 refers to the material with the largest occupancy rate in the housing 20.

[0166] The material of the side wall 212 may be of multiple types. For example, the base material of the side wall 212 may include metal, and exemplary metals include, but are not limited to, copper, iron, aluminum, steel, and aluminum alloys. Selectively, the base material of the side wall 212 may include steel, such as stainless steel. The side wall 212 made of the above metal material has excellent mechanical strength, is resistant to deformation, and can improve the structural stability of the side wall 212, thereby improving the reliability of the battery cell 7. In each embodiment of this application, the base material of the side wall 212 refers to the material that occupies the largest proportion of the side wall 212.

[0167] In some embodiments, the substrate material of the sidewall 212 includes steel, and the thickness of the sidewall 212 is 0.3 mm to 0.9 mm, and selectively 0.3 mm to 0.55 mm. When the thickness of the sidewall 212 is within the above range, the mechanical strength of the sidewall 212 is relatively high and it is less prone to deformation, which is further advantageous when used in combination with a silicon-containing negative electrode to improve the energy density of the battery cell 7, while also giving the battery cell 7 excellent reliability in use.

[0168] For example, the thickness of the side wall 212 may be in the range of 0.3 mm, 0.4 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or any two of the above values.

[0169] In some embodiments, the side wall 212 is formed integrally with the end wall 211, which is advantageous for simplifying the manufacturing process. The base material of the end wall 211 includes, but is not limited to, metals such as copper, iron, aluminum, steel, and aluminum alloys. Selectively, the base material of the end wall 211 includes steel such as stainless steel. The end wall 211 made of the above metal material has excellent mechanical strength, is resistant to deformation, and can improve the structural stability of the end wall 211, thereby improving the reliability of use of the battery cell 7.

[0170] In some embodiments, the base material of the end wall 211 includes metal, and the thickness of the end wall 211 is 0.3 mm to 0.9 mm. For example, the base material of the end wall 211 includes steel, and the thickness of the end wall 211 is 0.3 mm to 0.9 mm.

[0171] In some embodiments, the capacitance surface density of the negative electrode plate is 3.2 mAh / cm³. 2 The base material of the side wall 212 includes steel, and the thickness of the side wall 212 is 0.3 mm to 0.9 mm. The negative electrode plate with the above capacitance surface density is used in combination with the side wall 212 of the above thickness, which is advantageous in improving the energy density of the battery cell 7, as well as providing the battery cell 7 with excellent reliability and improving cycle performance.

[0172] In some embodiments, the capacitance surface density of the negative electrode plate is 3.3 mAh / cm³. 2 From 11.5mAh / cm² 2 The base material of the side wall 212 includes steel, and the thickness of the side wall 212 is 0.3 mm to 0.80 mm. The negative electrode plate with the above capacitance surface density is used in combination with the side wall 212 of the above thickness, which is advantageous in improving the energy density of the battery cell 7, as well as providing the battery cell 7 with excellent reliability and improving cycle performance.

[0173] In some embodiments, the capacitance surface density of the negative electrode plate is 3.96 mAh / cm³. 2 From 11.5mAh / cm² 2 The base material of the side wall 212 includes steel, and the thickness of the side wall 212 is 0.3 mm to 0.50 mm. The negative electrode plate with the above capacitance surface density is used in combination with the side wall 212 of the above thickness, which is advantageous in improving the energy density of the battery cell 7, as well as providing the battery cell 7 with excellent reliability in use and improving cycle performance.

[0174] In the embodiments of this application, the capacitance surface density of the negative electrode plate has a meaning known in the art and can be detected using instruments and methods known in the art. For example, a counter electrode is constructed with the above-mentioned negative electrode plate and metallic lithium sheet, a CR2430 type button cell is assembled in a glove box protected by argon gas using the electrolyte and separator of Example 1, the resulting button cell is left standing for 12 hours, then discharged at 25°C with a constant current of 0.05C to 0.005V, left standing for 10 minutes, discharged at a constant current of 50μA to 0.005V, left standing for 10 minutes, discharged at a constant current of 10μA to 0.005V, then charged at 0.1C to 2V, the charged capacity is recorded, and the ratio of the charged capacity to the area of ​​the negative electrode plate is the capacitance surface density.

[0175] In the embodiments of this application, the thickness of the side wall 212 is as known in the art and can be detected using instruments and methods known in the art, for example, by measuring with a spiral micrometer or caliper.

[0176] The embodiments of this application can further improve the energy density and operational reliability of the battery cell 7, and are also advantageous for improving cycle performance, by adjusting at least one of the following conditions of the negative electrode film layer.

[0177] In some embodiments, the surface density of the negative electrode film layer is 10.5 mg / cm³. 2 The following is the case: selectively 6 mg / cm³ 2 From 10 mg / cm³ 2 That is the case.

[0178] In some embodiments, the porosity of the negative electrode film layer is 10% or more and less than 100%, selectively between 20% and 40%.

[0179] In some embodiments, the compaction density of the negative electrode film layer is 1.75 g / cm³. 3 The following is the case, selectively 1.4 g / cm³ 3 From 1.7 g / cm³ 3 That is the case.

[0180] In the embodiments of this application, the surface density of the negative electrode film layer has a meaning known in the art and can be tested using methods and equipment known in the art. For example, a negative electrode plate coated on one side and cold-pressed (if the negative electrode plate is coated on both sides, the negative electrode film layer on one side can be wiped off first) is taken, punched out into a small disc with an area of ​​S1, and its weight is recorded as M1. Next, the negative electrode film layer of the weighed negative electrode plate is wiped off, the weight of the negative electrode current collector is weighed, and recorded as M0. Surface density of the negative electrode plate = (M1 - M0) / S1.

[0181] In the embodiments of this application, the consolidation density of the negative electrode film layer is as known in the art and can be tested using methods and equipment known in the art, for example, consolidation density of the negative electrode film layer = surface density of the negative electrode film layer / thickness of the negative electrode film layer. The thickness of the negative electrode film layer is as known in the art and can be tested using methods known in the art, for example, by measuring it using a micrometer (e.g., Mitutoyo 293-100, accuracy 0.1 μm).

[0182] In the embodiments of this application, the porosity of the negative electrode film layer has a meaning known in the art and can be tested using methods and equipment known in the art. For example, a negative electrode plate coated on one side and cold-pressed (if the negative electrode plate is coated on both sides, the negative electrode film layer on one side can be wiped off first) is taken, punched into a small disc sample of a certain area, the apparent volume V1 of the negative electrode plate is calculated, and the true volume V2 of the negative electrode plate is obtained by measuring the true volume V2 of the negative electrode plate using a true density tester with an inert gas (e.g., helium or nitrogen gas) as the medium and using the gas displacement method. Porosity of the negative electrode film layer = (V1 - V2) / V1 × 100%. Multiple negative electrode plate samples (e.g., 30) with good appearance and no powder fallout at the edges are taken and tested, and the results may be averaged, thereby improving the accuracy of the test results. The testing equipment may be a Micromeritics AccuPyc II 1340 true density tester.

[0183] Figure 6 is a schematic cross-sectional view of a cylindrical battery cell according to some embodiments of this application, Figure 7 is an enlarged schematic view of location A of the cylindrical battery cell shown in Figure 6, and Figure 8 is a schematic cross-sectional view of a battery cell according to some embodiments of this application.

[0184] As shown in Figures 6 to 8, in some embodiments, the battery cell 7 includes a housing 20 and an electrode assembly 10 housed within the housing 20, the housing 20 includes a side wall 212 which surrounds the electrode assembly 10, the electrode assembly 10 includes a main body 12 which includes a central region 121 and two end regions 122 which are positioned along its own axial direction, the central region 121 being located between the two end regions 122, where, along the radial direction of the main body 12, the distance between the outer surface of the central 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.

[0185] In Figures 6 and 7, the X direction represents the axial direction of the main body 12, and the axial direction of the main body 12, i.e., the axial direction of the electrode assembly 10, is parallel to the axial direction of the housing 20. The Y direction represents the radial direction of the main body 12, and the radial direction of the main body 12, i.e., the radial direction of the electrode assembly 10, is parallel to the radial direction of the housing 20. The X direction is perpendicular to the Y direction.

[0186] During the charging process of the battery cell 7, the main body portion 12 undergoes volume expansion, which may create a risk of the main body portion 12 pressing against the side wall 212. The internal stress at each point in the radial direction Y of the main body portion 12 is approximately the same, and the degree of freedom of expansion in the end region 122 is relatively high. Therefore, in the axial direction X, the end region 122 of the main body portion 12 may further press against the middle region 121, thereby increasing the internal stress in the middle region 121, making the degree of expansion in the radial direction Y greater, and increasing the risk of the middle region 121 pressing against the side wall 212 and causing it to break. In the embodiment of this application, a gap is set between the main body 12 and the side wall 212. The presence of this gap ensures an expansion space in the main body 12 in advance, reducing the risk of the main body 12 pressing against the side wall 212. Furthermore, the gap between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 is relatively reduced, while the gap between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 is relatively increased. The middle region 121 ensures a sufficient expansion space in advance, effectively reducing the pressing force of the main body 12 against the side wall 212, thereby improving the reliability of the battery cell 7.

[0187] In the embodiments of this application, the distance between the outer surface of the central region 121 and the inner surface 212b of the side wall 212 may be understood to be greater than the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212, and the minimum value of the distance between the outer surface of the central region 121 and the inner surface 212b of the side wall 212 may be understood to be 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.

[0188] The inner surface 212b of the side wall 212 is the surface of the side wall 212 facing the main body 12, and the outer surface 12a of the main body 12 may be understood as the surface of the main body 12 facing the side wall 212. Specifically, for example, the end region 122 includes an end face 122a that is separated from the middle region 121, and the size of the main body 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 taken as the origin, and the position of the end face 122a of the other end region 122 is L. The distance between the main body 12 and the side wall 212 in L / 3 of the main body 12 is measured, and the distance between multiple positions on the outer surface 12a of L / 3 of the main body 12 and the corresponding side wall 212 is measured, and the average value is taken to determine the distance at this location.

[0189] In Figure 7, W1 represents the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 at one location, and W2 represents the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212 at one location, with W2 being greater than W1.

[0190] The end region 122 has a fixed size in the axial direction X, and each of the two end faces 122a of the main body 12 that face each other along the axial direction X is the respective end face 122a of the two end regions 122, and the end region 122 is the region between the end face 122a and the distance end face H2. For example, H2 may be 20 mm, that is, the size of the end region 122 in the axial direction X may be 20 mm. H2 shown in Figure 8 represents the size of the end region 122 in the axial direction X.

[0191] The central region 121 is a structure having a constant size in the axial direction X, and the central region 121 is the region between the central cross section and the central cross section H1, and the central cross section is a cross section that includes the center point of the main body 12 on its own axis, and this central cross section is perpendicular to the axis of the main body 12. For example, H1 may be 5 mm and 2H1 may be 10 mm, that is, the size of the central region 121 in the axial direction X may be 10 mm. In Figure 8, 2H1 represents the size of the central region 121 in the axial direction X, M represents the axis of the main body 12, and N represents the line located in the central cross section of the main body 12.

[0192] The main body 12 of the electrode assembly 10 includes an end region 122 and a middle region 121. That is, the main body 12 includes an end region 122, a middle region 121, and another end region 122, which are installed along the axial direction X. The end region 122 may be directly connected to the middle region 121. In other words, the main body 12 includes an end region 122, a middle region 121, and another end region 122, which are installed sequentially along the axial direction X. Of course, a connecting region may be included between the end region 122 and the middle region 121. For example, the main body 12 includes an end region 122, a connecting region, a middle region 121, a connecting region, and another end region 122, which are installed along the axial direction X.

[0193] In some embodiments, the mass content of silicon in the negative electrode film layer is 1% to 32%, selectively 2% to 19%, and even more selectively 6% to 13%. When the mass content of silicon in the battery cell 7 system is within the above range, the energy density of the battery cell 7 can be improved, and the negative electrode film layer undergoes volume expansion during the charging process, which, in cooperation with the structural features of the battery cell 7 (for example, the gap between the outer surface of the central region 121 and the inner surface 212b of the side wall 212 is greater than the gap between the outer surface of the end region 122 and the inner surface 212b of the side wall 212), makes the gap between the housing 20 and the central region 121 of the electrode assembly 10 relatively large, pre-securing more sufficient expansion space, reducing the pressing force on the housing 20, improving the structural stability of the housing 20, and further improving the reliability of the battery cell 7 in use.

[0194] In some embodiments, in the direction from the end region 122 toward 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 tends to decrease first and then increase. The direction from the end region 122 toward the middle region 121 is parallel to the axial direction X of the main body 12, but the direction from the end region 122 toward the middle region 121 is unidirectional.

[0195] The gap between the outer surface of the central region 121 and the inner surface 212b of the side wall 212 tends to decrease first and then increase, with the gap becoming larger closer to the center position in the axial direction X of the central region 121. This increases the pre-secured expansion space, further reducing the risk of the central region 121 pressing against the housing 20 and improving the reliability of the battery cell 7.

[0196] In the embodiments of this application, the housing 20 may be installed in various structural forms to increase the expansion space of the central region 121, and the structural forms of the housing 20 will now be described.

[0197] As shown in Figures 6 to 8, in some embodiments, the side wall 212 includes a first portion 2121 and a second portion 2122 installed along the axial direction X, the first portion 2121 facing the middle region 121 along the radial direction Y, the second portion 2122 protruding from the surface of the first portion 2121 facing the main body 12 along the radial direction Y, and the second portion 2122 facing the end region 122 along the radial direction Y.

[0198] During the charging process of the battery cell 7, the end region 122 expands radially Y toward the second portion 2122, and the middle region 121 expands radially Y toward the first portion 2121, and the degree of expansion of the middle region 121 is greater than that of the first portion 2121. The second portion 2122 protrudes from the first portion 2121 along the radial Y, and the gap between the inner surface 212b of the second portion 2122 and the outer surface of the end region 122 is relatively smaller, while the gap between the inner surface 212b of the first portion 2121 and the outer surface of the middle region 121 is larger. This allows for more expansion space in the middle region 121, reduces the risk of the middle region 121 pressing against the housing 20, and is advantageous in improving the reliability of the battery cell 7.

[0199] Selectively, the first portion 2121 may further face a portion of the end region 122 along the radial Y direction, and the second portion 2122 may face another portion of the end region 122 along the radial Y direction.

[0200] Selectively, in the direction from the central region 121 toward the end region 122, the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 tends to increase. The direction from the central region 121 toward the end region 122 is parallel to the axial direction X of the main body 12, but the direction from the central region 121 toward the end region 122 is unidirectional, and this direction is parallel to the direction from the end region 122 toward the central region 121, but in the opposite direction.

[0201] The end region 122 has a configuration having a constant size in the axial direction X. The closer the end region 122 is to the end face 122a, the higher the degree of freedom of expansion and the lower the internal stress. Conversely, as the size increases from the end face 122a along the axial direction X, the internal stress increases and the degree of expansion in the radial direction Y increases. In the embodiment of this application, the gap between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 tends to increase, thereby increasing the pre-secured expansion space. This reduces the risk of the end region 122 pressing against the housing 20 and is advantageous in improving the reliability of the battery cell 7.

[0202] In some embodiments, the second portion 2122 may be provided as at least one, for example, one or two.

[0203] For example, if one second portion 2122 is installed, the second portion 2122 may be located at either end of the main body 12 along the axial direction X.

[0204] Alternatively, exemplary, two second portions 2122 may be installed, with each second portion 2122 located on either side of the first portion 2121 along the axial X. When two second portions 2122 are installed, each second portion 2122 is installed correspondingly to one of the two end regions 122 of the main body 12, and the engagement between the end regions 122 and the second portions 2122 is advantageous in reducing the risk of the end regions 122 pressing against the housing 20. At the same time, the second portions 2122 can further improve the mechanical strength of the housing 20, improve the deformation resistance of the housing 20, and further improve the reliability of the battery cell 7.

[0205] In some embodiments, the size of the first portion 2121 along the axial X is 0.4 to 0.98 times the size of the side wall 212 along the axial X, for example, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.98, or any of the above values. In Figure 6, L1 is the size of the first portion 2121 along the axial X, and L0 is the size of the side wall 212 along the axial X.

[0206] If the size of the first portion 2121 along the axial X is within the above range, the middle region 121 can provide sufficient expansion space, further reducing the risk of the middle region 121 pressing against the housing 20, which is advantageous in improving the reliability of use of the battery cell 7.

[0207] In some embodiments, the outer circumferential surface 212a of the side wall 212 is a cylindrical surface, thereby the battery cell 7 has a standard cylindrical structure, meaning that during the charging process of the battery cell 7, the side wall 212 does not deform at all, or the degree of expansion deformation of the first part 2121 and the second part 2122 is relatively small, and the difference in deformation is relatively small. In other words, the effect of the expansion of the electrode assembly 10 on the side wall 212 is relatively small, or even nonexistent, improving the structural stability of the battery cell 7. In this structural form, the side wall 212 is installed with non-uniform thickness, and the non-flattened inner surface 212b of the side wall 212 pre-secures sufficient expansion space in the central region 121. Of course, in some other embodiments, the outer circumferential surface 212a of the side wall 212 may also be an arcuate surface projecting away from the electrode assembly 10. In each of the embodiments of this application, the outer peripheral surface 212a and the inner surface 212b of the side wall 212 face each other along the radial direction Y.

[0208] Figure 9 is a schematic cross-sectional view of a cylindrical battery cell according to some other embodiments of this application.

[0209] As shown in Figure 9, in some other embodiments, the inner surface 212b of the side wall 212 is an arcuate surface, that is, the surface of the side wall 212 facing the electrode assembly 10 is an arcuate surface and is concave toward the direction away from the electrode assembly 10. By setting the arcuate surface of the side wall 212, sufficient expansion space can be secured in advance by the central region 121, and specifically, the degree of partial concavity of the side wall 212 facing the central region 121 can be set to be relatively deep, and the degree of partial concavity of the side wall 212 facing the end region 122 can be set to be relatively shallow.

[0210] For example, the side walls 212 may be installed with equal thickness or with unequal thickness.

[0211] When the sidewalls 212 are installed at equal thickness, the process of forming the sidewalls 212 is simpler, and when the electrode assembly 10 applies pressure to the sidewalls 212, the deformation of the sidewalls 212 is more mitigated, stress concentration problems are less likely to occur, and the reliability of the sidewalls 212 can be improved. Selectively, along the radial direction Y, the sidewalls 212 protrude away from the electrode assembly 10, and the entire sidewall 212 exhibits a slightly protruding structural form. Specifically, the outer circumferential surface 212a of the sidewalls 212 may be an arcuate surface, and this arcuate surface protrudes away from the electrode assembly 10. Figure 8 shows a structural form in which the sidewalls 212 are installed at equal thickness.

[0212] Figure 10 is a schematic cross-sectional view of a cylindrical battery cell according to yet another embodiment of the present application.

[0213] As shown in Figure 10, when the side walls 212 are installed with non-uniform thickness, the thickness of the side walls 212 tends to decrease first and then increase in the direction from one end region 122 to the other end region 122. This tendency for the thickness of the side walls 212 to decrease first and then increase ensures sufficient expansion space in the middle region 121. Specifically, a larger gap may be set corresponding to the position of the middle region 121, thereby ensuring even more sufficient expansion space in advance.

[0214] Selectively, along the radial direction Y, the side wall 212 protrudes away from the electrode assembly 10, and the entire side wall 212 exhibits a slightly protruding structural form, easily realizing the pre-emption of a larger expansion space than the central region 121. Specifically, the outer circumferential surface 212a of the side wall 212 may be an arcuate surface, and this arcuate surface protrudes away from the electrode assembly 10. Of course, if the side wall 212 is installed with non-uniform thickness, the outer circumferential surface of the side wall 212 may be a cylindrical surface.

[0215] In each of the embodiments of this application, the spacing test is performed under a state of charge (SOC) of 0% for the cylindrical battery cell 7, and can be performed using equipment and methods known in the art. Specifically, at 25°C, the cylindrical battery cell 7 is discharged to 2.5V at 0.33C, then discharged to 2.5V at 0.1C, at which point the cylindrical battery cell 7 is in a 0% charge state. The cylindrical battery cell 7 in a 0% charge state is placed in an X-ray computed tomography (X) scanner (brand: GE, model: Phoenix Nanotom M), and the test is performed in reference to the ISO 15708:2002 standard to obtain computed tomography images of the cylindrical battery cell 7 in the axial X and radial Y directions. Based on the images, the spacing between each point on the side wall 212 and the main body 12 is measured, thereby measuring the spacing between the middle region 121 and the side wall 212, and the spacing between the end region 122 and the side wall 212.

[0216] Principle of X-ray computed tomography: When an X-ray beam of constant energy and intensity passes through the battery cell 7, a tomographic image is acquired by an image reconstruction algorithm based on the attenuation and distribution differences of the X-ray beam in the object being detected. Finally, a three-dimensional image of the sample is acquired using computer information processing and image reconstruction techniques.

[0217] In some embodiments, when the battery cell 7 is 100% charged, the distance along the radial Y direction between the outer surface of the central region 121 and the inner surface 212b of the side wall 212 is the first central distance, and when the battery cell 7 is 0% charged, the distance along the radial Y direction between the outer surface of the central region 121 and the inner surface 212b of the side wall 212 is the second central distance, where the first central distance is smaller than the second central distance, and the difference between the first central distance and the second central distance is 0.05 mm or less.

[0218] In the battery cell 7, the negative electrode active material may undergo volume expansion during the charging process. When the battery cell 7 is at 100% SOC, the volume expansion of the negative electrode active material is relatively large. In this case, the distance along the radial Y direction between the outer surface of the central region 121 and the inner surface 212b of the side wall 212 is the first central distance. Conversely, when the battery cell 7 is at 0% SOC, it is in a fully discharged state, and the volume expansion of the negative electrode active material is relatively small. In this case, the distance along the radial Y direction between the outer surface of the central region 121 and the inner surface 212b of the side wall 212 is the second central distance. When the difference between the first and second central distances is within the above range, the volume expansion of the battery cell 7 during the charging process is relatively small, which is advantageous in improving the structural stability of the battery cell 7 and improving the reliability of the battery cell 7 in use.

[0219] For example, the difference between the first midpoint spacing and the second midpoint spacing is 0.05 mm or less, and is within the range of, 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 any two of the above values.

[0220] By measuring the distance between the same position in the central region 121 and the side wall 212 under different charge states, the difference between the first central distance and the second central distance can be calculated. Furthermore, by measuring multiple distances between multiple positions in the central region 121 and the side wall 212 under different charge states, the average value for the multiple distances can be calculated and used as the difference between the first end distance and the second end distance. For example, the difference in distance between a first position in the central region 121 and the side wall 212 under different charge states can be measured and used as the first distance, and the difference in distance between a second position in the central region 121 and the side wall 212 under different charge states can be measured and used as the second distance. The average value of the first and second distances is the difference between the first central distance and the second central distance.

[0221] In the embodiments of this application, the interval measurement at the 100% charged state of charge (SOC) of the cylindrical battery cell 7 can be measured using instruments and methods known in the art. Specifically, at 25°C, the manufactured cylindrical battery cell 7 is charged to 4.25V at 0.33C, and then charged to 4.25V at 0.1C, at which point the cylindrical battery cell 7 is in a 100% charged state. A cylindrical battery cell 7 in a 100% charged state is placed in an X-ray computed tomography (X) scanner (brand: GE, model: Phoenix Nanotom M), and a test is performed in accordance with the ISO 15708:2002 standard to obtain computed tomography images of the cylindrical battery cell 7 in the axial X and radial Y directions. Based on the images, the distance between each point of the side wall 212 and the main body 12 is measured, thereby measuring the distance between the outer surface of the middle region 121 and the inner surface 212b of the side wall 212, and the distance between the outer surface of the end region 122 and the inner surface 212b of the side wall 212.

[0222] In some embodiments, when the battery cell 7 is 100% charged, the distance along the radial Y direction between the end region 122 and the inner surface 212b of the side wall 212 is the first end distance, and when the battery cell 7 is 0% charged, the distance along the radial Y direction between the end region 122 and the inner surface 212b of the side wall 212 is the second end distance, where the first end distance is smaller than the second end distance, and the difference between the first end distance and the second end distance is 0.05 mm or less.

[0223] When the battery cell 7 is at 100% SOC, the degree of volume expansion of the negative electrode active material is relatively large. In this case, the distance along the radial Y direction between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 is the first end distance. Conversely, when the battery cell 7 is at 0% SOC, the degree of volume expansion of the negative electrode active material is relatively small. In this case, the distance along the radial Y direction between the outer surface of the end region 122 and the inner surface 212b of the side wall 212 is the second end distance. When the difference between the first and second end distances is within the above range, the degree of volume expansion of the battery cell 7 during the charging process is relatively small, which is advantageous in improving the structural stability of the battery cell 7 and improving the reliability of the battery cell 7 in use.

[0224] For example, the difference between the first end spacing and the second end spacing is 0.05 mm or less, and is within the range of, 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 any two of the above values.

[0225] By measuring the distance between the same position in the end region 122 and the side wall 212 under different charge states, the difference between the first end distance and the second end distance can be calculated. Furthermore, by measuring multiple distances between multiple positions in the end region 122 and the side wall 212 under different charge states, the average value for these multiple distances can be calculated and used as the difference between the first end distance and the second end distance. For example, the distance between a first position in the end region 122 and the side wall 212 under different charge states can be measured to determine the first distance, and the distance between a second position in the end region 122 and the side wall 212 under different charge states can be measured to determine the second distance. The average value of the first and second distances is the difference between the first and second end distances.

[0226] In some embodiments, the absolute value of the difference between the first mid-section spacing and the second mid-section spacing is the mid-section variable, and the absolute value of the difference between the first end-section spacing and the second end-section spacing is the end-section variable, where the absolute value of the difference between the mid-section variable and the end-section variable is 0.05 mm or less.

[0227] When the absolute value of the difference between the central variable and the end variable falls within the above range, the difference in the degree of volume expansion between the end region 122 and the central region 121 during the charging process of the battery cell 7 is relatively small, the difference in the degree of volume expansion of the entire main body 12 is relatively small, it is less likely to cause localized excessive pressure on the housing 20, and the reliability of the battery cell 7 is significantly improved.

[0228] For example, the absolute value of the difference between the midpoint variable and the endpoint variable is 0.05 mm or less, and is within the range of, 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 any two of the above values.

[0229] As a specific embodiment of the present application, as shown in Figures 4 to 7, the battery cell 7 includes a housing 20 and an electrode assembly 10 housed within the housing 20, the housing 20 includes a side wall 212 which surrounds the electrode assembly 10, the electrode assembly 10 includes a main body 12 which includes a central region 121 and two end regions 122 which are positioned along its own axial direction X, the central region 121 being located between the two end regions 122, and the side wall 212 along the axial direction X The structure includes a first portion 2121 and a second portion 2122, wherein the first portion 2121 faces the central region 121 along the radial direction Y, and the second portion 2122 protrudes from the surface of the first portion 2121 facing the main body 12 along the radial direction Y, and the second portion 2122 faces the end region 122 along the radial direction Y, where the distance between the outer surface of the central 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. The greater distance between the inner surface 212b of the first portion 2121 and the outer surface of the central region 121 is advantageous in that it pre-secures more expansion space in the central region 121, reduces the risk of the central region 121 pressing against the housing 20, and improves the reliability of use of the battery cell 7.

[0230] As another specific embodiment of the present application, as shown in Figure 8, the battery cell 7 includes a housing 20 and an electrode assembly 10 housed within the housing 20, the housing 20 includes a side wall 212 which surrounds the electrode assembly 10, the electrode assembly 10 includes a main body 12 which includes a middle region 121 and two end regions 122 which are positioned along its own axial direction X, the middle region 121 being located between the two end regions 122, the inner surface 212b of the side wall 212 being an arcuate surface and recessed toward the direction away from the electrode assembly 10, and the side wall 212 may be of equal thickness, where 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 along the radial direction of the main body 12. The larger gap between the inner surface 212b of the side wall 212 and the outer surface of the central region 121 allows for more expansion space to be pre-secured in the central region 121, reducing the risk of the central region 121 pressing against the housing 20 and improving the reliability of the battery cell 7.

[0231] Examples The following examples provide a more detailed description of the contents disclosed in the examples of this application, and these examples are for illustrative purposes only, as it will be obvious to those skilled in the art that various modifications and changes can be made within the scope of the contents disclosed in the examples of this application. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on mass, and all reagents used in the examples can be obtained commercially or synthesized according to conventional methods and can be used directly without further processing, and all instruments used in the examples can be obtained commercially.

[0232] Example 1 1. Manufacturing of positive electrode plates The positive electrode plate includes a positive electrode current collector and a positive electrode film layer. The positive electrode film layer is located on both sides of the positive electrode current collector, which is aluminum foil. The positive electrode film layer is formed by uniformly coating the surface of the aluminum foil of the positive electrode current collector with a positive electrode slurry (solvent is N-methylpyrrolidone NMP), drying, and cold pressing. The positive electrode film layer contains a positive electrode active material, a conductive agent carbon black (Super P), and an adhesive polyvinylidene fluoride (PVDF) in a weight ratio of 97:1:2.

[0233] The positive electrode active material has the molecular formula LiNi 0.8 Co 0.1 Mn 0.1 It contains a layered transition metal oxide called O2(NCM811).

[0234] 2. Manufacturing of the negative electrode plate The negative electrode plate includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer is located on both sides of the negative electrode current collector. The negative electrode current collector is copper foil. The negative electrode film layer is formed by uniformly coating the surface of the copper foil of the negative electrode current collector with a negative electrode slurry (solvent is deionized water), drying, and cold pressing. The negative electrode film layer contains a silicon-based material (specifically silicon oxide) in a weight ratio of 12.6:82.4:1.9:0.1:3, graphite, conductive agent carbon black, conductive agent carbon nanotubes, and adhesive polyacrylic acid. The surface density of the negative electrode film layer is 9.0 mg / cm². 2 The porosity is 22.1%, and the compacted density is 1.7 g / cm³. 3 That is the case.

[0235] 3. Separator The separator is a polypropylene (PP) film layer.

[0236] 4. Manufacturing of electrolyte The electrolyte contained an organic solvent and a lithium salt. Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain the organic solvent. Then, a thoroughly dried lithium salt LiPF6 was dissolved in the resulting organic solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0237] 5. Manufacturing of battery cells The positive electrode plate, separator, and negative electrode plate are stacked in order, with the separator positioned between the positive and negative electrode plates to provide isolation. The positive electrode plate, separator, and negative electrode plate are wound together to obtain an electrode assembly. The electrode assembly is placed in a cylindrical housing. After drying, an electrolyte is injected, and a battery cell is obtained through processes such as vacuum sealing, standing, chemical formation, and shaping. Here, the electrode assembly has a cylindrical structure, the housing has a cylindrical structure, the housing includes a case and end caps, the case includes integrally formed side walls and end walls, the side walls are installed surrounding the electrode assembly, and the end caps and end walls face each other along the axial direction of the housing.

[0238] Comparative Example 1 A battery cell was manufactured in the same manner as in Example 1, the only difference from Example 1 being that the manufacturing of the negative electrode plate in Comparative Example 1 includes the following steps.

[0239] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer is located on both sides of the negative electrode current collector. The negative electrode current collector is copper foil. The negative electrode film layer is formed by uniformly coating the surface of the copper foil of the negative electrode current collector with a negative electrode slurry (solvent is deionized water), drying, and cold pressing. The negative electrode film layer contains graphite, conductive carbon black, conductive carbon nanotubes, and adhesive polyacrylic acid in a weight ratio of 95:1.9:0.1:3.

[0240] Comparative Example 2 The battery cell was manufactured in the same manner as in Example 1, with the differences being that the electrode assembly has a flattened structure, the housing has a rectangular parallelepiped structure, and the battery cell manufacturing steps are as follows.

[0241] The above positive electrode plate, separator, and negative electrode plate are stacked in sequence, with the separator positioned between the positive electrode plate and the negative electrode plate to perform an isolation function. The positive electrode plate, separator, and negative electrode plate are wound to obtain an electrode assembly. The electrode assembly has a flat structure. The electrode assembly is placed in a housing having a rectangular parallelepiped structure, and after drying, an electrolytic solution is injected. Through processes such as vacuum sealing, standing, formation, and shaping, a battery cell is obtained.

[0242] Performance testing 1. Expansion volume test of the battery cell The battery cell in a 0% state of charge is immersed in silicone oil, and its mass is weighed and designated as m0.

[0243] The battery cell in a 100% state of charge is immersed in silicone oil, and its mass is weighed and designated as m1.

[0244] When the density of the silicone oil is ρ シリコンオイル the volume change ΔV of the battery cell between the 100% state of charge and the 0% state of charge is ΔV = (m0 - m1) / ρ シリコンオイル When evaluating the usage reliability of the battery cell with ΔV, the smaller ΔV is, the smaller the volume expansion of the battery cell, and the higher the usage reliability. The larger ΔV is, the larger the volume expansion of the battery cell, and the lower the usage reliability.

[0245] 2. Energy density test of the battery cell Under a constant voltage (both in the examples and comparative examples, it is 4.25 V), multiply the discharge capacity (Ah) of the first cycle by the ratio of the discharge voltage to the mass of the battery cell.

[0246] Energy density = discharge capacity (Ah) of the first cycle × discharge voltage (4.25 V) / mass (kg) of the battery cell.

[0247] Here, the discharge capacity of the first cycle is tested according to the following steps: At 45°C, the battery cell manufactured above is fully charged at 1C and then fully discharged at 1C. This is one cycle of charge-discharge process. Record the discharge capacity at this time, which is the discharge capacity of the first cycle.

[0248] The test results are shown in Table 1.

[0249] [Table 1]

[0250] In Table 1, the mass content of silicon element refers to the mass content in the negative electrode film layer.

[0251] As can be seen from Table 1, compared to Comparative Examples 1 and 2, Example 1 significantly improves the energy density of the battery cell by introducing silicon into the negative electrode active material, and because the housing has a cylindrical structure, the volume expansion of the battery cell does not become too large, and the reliability of the battery cell remains excellent. When the expansion volume is 0.6 mL or less, the reliability of the battery cell is relatively high in all cases, and when the expansion volume is 0.57 mL or less, and even more selectively 0.34 mL, the reliability of the battery cell is further improved.

[0252] Examples 2-1 to 2-5 The battery cell was manufactured in the same manner as in Example 1, with the difference being that the manufacturing of the negative electrode plate in Examples 2-1 to 2-5 included the following steps: The negative electrode plate includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer is located on both sides of the negative electrode current collector. The negative electrode current collector is copper foil. The negative electrode film layer is formed by uniformly coating the surface of the copper foil of the negative electrode current collector with a negative electrode slurry (solvent is deionized water), drying, and cold pressing. The negative electrode film layer contains a silicon-based material (specifically silicon oxide), graphite, conductive carbon black, conductive carbon nanotubes, and adhesive polyacrylic acid, and the mass content and capacitance surface density of the silicon element are adjusted.

[0253] Examples 3-1 to 3-4 Battery cells were manufactured using the same method as in Example 1, with the only difference being that the thickness of the side walls was adjusted in Examples 3-1 to 3-4.

[0254] Example 4 The battery cell was manufactured in the same manner as in Example 1, with the only difference being that the material of the side wall was adjusted in Example 4.

[0255] Performance testing The expansion volume test and energy density test of the battery cells are performed according to the test methods shown in Table 1.

[0256] 3. Battery cycle performance test At 45°C, the manufactured battery cell is fully charged at 1C and then fully discharged at 1C. This constitutes one charge-discharge cycle, and the discharge capacity at this time is recorded, i.e., the discharge capacity of the first cycle. A charge-discharge cycle test is performed on the battery cell according to the above method, and the discharge capacity after each cycle is recorded until the discharge capacity of the battery cell decreases to 80% of the initial discharge capacity. The cycle performance of the battery cell is characterized by the number of cycles at this time. The higher the number of cycles of the battery cell, the better the cycle performance.

[0257] The test results are shown in Table 2.

[0258] [Table 2]

[0259] As can be seen from Table 2, Examples 2-1 to 2-5 can synchronously adjust the capacitance surface density by adjusting the mass content of silicon element, which is advantageous in that it engages with side walls of a certain thickness, improving both the cycle performance and energy density of the battery cell, and also reduces the volume expansion of the battery cell relatively. Furthermore, the embodiments of this application are applied to different silicon-based materials, which engage with side walls of 0.3 mm to 0.9 mm, which is advantageous in that it improves both the cycle performance and energy density of the battery cell, and also reduces the volume expansion of the battery cell relatively.

[0260] Examples 3-1 to 3-4 are advantageous in terms of engagement with the mass content of the silicon element by adjusting the thickness of the sidewall, are advantageous for simultaneously improving the cycle performance and energy density of the battery cell, and relatively reduce the volume expansion of the battery cell. Moreover, the examples of the present application are applicable to sidewalls of different materials, such as steel or aluminum. The sidewalls of the above metal materials have high mechanical strength, can effectively improve the problem of volume expansion, and can simultaneously improve the cycle performance and energy density of the battery cell.

[0261] Example 5 A battery cell was manufactured in the same manner as in Example 1. The difference from Example 1 is that in Example 5, the surface density, porosity, and compaction density of the negative electrode film layer were adjusted.

[0262] The performance test method is as shown in the test steps of Table 2.

[0263] The test results are as shown in Table 3.

[0264]

Table 3

[0265] As can be seen from Table 3, Example 5 is advantageous for simultaneously improving the cycle performance and energy density of the battery cell by adjusting the surface density, porosity, compaction density, etc. of the negative electrode film layer, and relatively reduces the volume expansion of the battery cell.

[0266] Although illustrative examples have been shown and described, those skilled in the art should understand that the above examples should not be construed as limitations to the present application, and modifications, substitutions, and alterations can be made to the examples without departing from the spirit, principles, and scope of the present application.

[0267] While exemplary embodiments have been described, those skilled in the art should understand that the embodiments described above should not be construed as limitations on this application, and that modifications, substitutions, and alterations can be made to the embodiments without departing from the spirit, principles, and scope of this application. [Explanation of Symbols]

[0268] X: Axial direction, Y: Radial direction, 1: Vehicle, 2: Battery, 3: Controller, 4: Motor, 5: Housing, 5a: First housing section, 5b: Second housing section, 5c: Enclosure space, 6: Battery module, 7: Battery cell, 10: Electrode assembly, 111: First tab, 112: Second tab, 12: Main body, 121: Middle region, 122: End region, 122a: End face, 12a: Outer surface, 20: Housing, 21: Case, 211: End wall, 212: Side wall, 2121: First part, 2122: Second part, 212a: Outer surface, 212b: Inner surface, 22: End cap, 30: Electrode terminal, 40: Current collection component.

Claims

1. It is a battery cell, An electrode assembly comprising a negative electrode plate, wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer installed on at least one side of the negative electrode current collector and containing a negative electrode active material, A housing that accommodates the electrode assembly, the housing includes side walls, and the side walls are installed surrounding the electrode assembly. Herein, the negative electrode active material contains silicon, and the housing has a cylindrical structure, in this battery cell.

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

3. The battery cell according to claim 2, wherein the mass content of the silicon element in the negative electrode film layer is 2% to 19%.

4. The battery cell according to claim 3, wherein the mass content of the silicon element in the negative electrode film layer is 6% to 13%.

5. The capacitance surface density of the negative electrode plate is 3.2 mAh / cm³. ２ The battery cell according to any one of claims 1 to 4.

6. The capacitance surface density of the negative electrode plate is 3.3 mAh / cm³. ２ From 11.5 mAh / cm² ２ The battery cell according to claim 5.

7. The capacitance surface density of the negative electrode plate is 3.96 mAh / cm³. ２ From 7.56 mAh / cm² ２ The battery cell according to claim 6.

8. The battery cell according to any one of claims 1 to 7, wherein the base material of the side wall includes steel, and the thickness of the side wall is 0.3 mm to 0.9 mm.

9. The battery cell according to claim 8, wherein the thickness of the side wall is 0.3 mm to 0.55 mm.

10. The negative electrode film layer further satisfies one or more of the following conditions: (1) The surface density of the negative electrode film layer is 10.5 mg / cm². ２ The following: (2) The porosity of the negative electrode film layer is 10% or more and less than 100%, (3) The compaction density of the negative electrode film layer is 1.75 g / cm³. ３ The following is: A battery cell according to any one of claims 1 to 9.

11. The electrode assembly includes a main body, the main body includes a middle region and two end regions positioned along the axial direction of the housing, the middle region being located between the two end regions, The battery cell according to any one of claims 1 to 10, wherein, along the radial direction of the housing, the distance between the outer surface of the central 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.

12. The battery cell according to claim 11, wherein, in the direction from the end region toward the middle region, the distance between the outer surface of the middle region and the inner surface of the side wall tends to decrease first and then increase.

13. The battery cell according to claim 11 or 12, wherein the side wall includes a first portion and a second portion installed along the axial direction, the first portion facing the middle region along the radial direction, the second portion protruding radially from the surface of the first portion facing the main body, and the second portion facing the end region along the radial direction.

14. The battery cell according to claim 13, wherein, in the direction from the central region toward the end region, the distance between the outer surface of the end region and the inner surface of the side wall tends to increase.

15. The battery cell according to claim 13 or 14, wherein two of the second parts are installed, and the two second parts are each located on both sides of the first part along the axial direction.

16. The battery cell according to any one of claims 13 to 15, wherein the size of the first portion along the axial direction is 0.4 to 0.98 times the size of the side wall along the axial direction.

17. The battery cell according to any one of claims 13 to 16, wherein the outer circumferential surface of the side wall is a cylindrical surface.

18. The battery cell according to claim 11 or 12, wherein the inner surface of the side wall is an arcuate surface and is concave in a direction away from the electrode assembly.

19. The battery cell according to claim 18, wherein the side walls are installed at equal thickness.

20. The battery cell according to claim 18, wherein, in the direction from one of the two end regions toward the other end region, the thickness of the side wall tends to decrease first and then increase.

21. The battery cell according to any one of claims 18 to 20, wherein the side wall protrudes toward a direction away from the electrode assembly.

22. When the battery cell is 100% charged, the radial distance between the outer surface of the central region and the inner surface of the side wall is the first central distance. When the battery cell is in a 0% charged state, the radial distance between the outer surface of the central region and the inner surface of the side wall is the second central distance. Here, the first central spacing is smaller than the second central spacing, and the difference between the first central spacing and the second central spacing is 0.05 mm or less, as described in any one of claims 11 to 21.

23. When the battery cell is 100% charged, the radial distance between the end region and the inner surface of the side wall is the first end distance. When the battery cell is in a 0% charged state, the radial distance between the end region and the inner surface of the side wall is the second end distance. The battery cell according to any one of claims 11 to 22, wherein the first end spacing is smaller than the second end spacing, and the difference between the first end spacing and the second end spacing is 0.05 mm or less.

24. When the battery cell is 100% charged, the radial distance between the outer surface of the central region and the inner surface of the side wall is the first central distance. When the battery cell is in a 0% charged state, the radial distance between the outer surface of the central region and the inner surface of the side wall is the second central distance, and the absolute value of the difference between the first central distance and the second central distance is the central variable. When the battery cell is 100% charged, the radial distance between the end region and the inner surface of the side wall is the first end distance. When the battery cell is in a 0% charged state, the radial distance between the end region and the inner surface of the side wall is the second end distance, and the absolute value of the difference between the first end distance and the second end distance is the end variable. Here, the absolute value of the difference between the middle variable and the end variable is 0.05 mm or less, as described in any one of claims 11 to 23.

25. The battery cell according to any one of claims 1 to 24, wherein the size of the housing along its own axial direction is 1.3 to 2.5 times the size of the housing along its own radial direction.

26. The housing has a size along its own axial direction of 50 mm to 150 mm, and / or The battery cell according to any one of claims 1 to 25, wherein the housing has a size of 40 mm to 80 mm along its radial direction.

27. The battery cell according to any one of claims 1 to 26, wherein the housing includes a case and an end cap, the case includes integrally formed side walls and end walls, the end walls and the end cap face each other along the axial direction of the housing, and the end cap is sealed to the side wall.

28. The electrode assembly includes a first tab and a second tab with opposite polarity, the first tab and the second tab each protruding from the main body, The battery cell according to claim 27, further comprising an electrode terminal insulated from the end wall, wherein the electrode terminal is electrically connected to the second tab, and the end wall is electrically connected to the first tab.

29. A battery comprising a battery cell as described in any one of claims 1 to 28.

30. A power consumption device comprising a battery as described in claim 29, wherein the battery is used to provide electrical energy.

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