Battery cell, manufacturing method and system thereof, battery and electric device

Abstract

The embodiments of the present application relate to a battery cell, a manufacturing method and a manufacturing system thereof, a battery, and an electrical device. The battery cell comprises: a shell having a wall portion; an electrode assembly housed in the shell; a pressure relief mechanism provided in the wall portion, the pressure relief mechanism comprising a weak portion, a main body portion, and a connecting portion, the weak portion being configured to be destroyed to release pressure when the pressure inside the shell reaches a threshold value, the main body portion being located within the area enclosed by the weak portion, the connecting portion being located outside the weak portion, and being used to connect to the wall portion; the main body portion protrudes in a direction away from the electrode assembly relative to the connecting portion, and the pressure relief mechanism is provided with a first recess at a position corresponding to the main body portion on the side facing the electrode assembly. The battery cell provided by the embodiments of the present application can improve the safety of the battery cell.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more particularly, to a battery cell and a manufacturing method and system thereof, a battery, and an electrical device. Background Art

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells.

[0003] In the development of battery technology, in addition to improving the performance of battery cells, safety is also an issue that cannot be ignored. If the safety of a battery cell cannot be guaranteed, the battery cell will be unusable. Therefore, how to enhance the safety of battery cells is a technical issue that needs to be addressed urgently in battery technology. Summary of the Invention

[0004] The present application provides a battery cell and a manufacturing method and system thereof, a battery, and an electrical device, which can enhance the safety of the battery cell.

[0005] In the first aspect, according to an embodiment of the present application, a battery cell is proposed, comprising: a shell having a wall portion; an electrode assembly, the electrode assembly being accommodated in the shell; a pressure relief mechanism, the pressure relief mechanism being arranged in the wall portion, the pressure relief mechanism comprising a weak portion, a main body portion and a connecting portion, the weak portion being configured to be destroyed to release pressure when the pressure inside the shell reaches a threshold value, the main body portion being located within an area enclosed by the weak portion, the connecting portion being located outside the weak portion and being used to connect to the wall portion; the main body portion protrudes in a direction away from the electrode assembly relative to the connecting portion, and the pressure relief mechanism is formed with a first recess at a position corresponding to the main body portion on a side facing the electrode assembly.

[0006] In the above scheme, according to the battery cell provided in the embodiment of the present application, the main body protrudes in the direction away from the electrode assembly relative to the connecting part, and a sudden cross-section occurs at the weak part, causing stress concentration in the weak part, and the pressure relief mechanism is formed with a first recess at a position corresponding to the main body on the side facing the electrode assembly, further aggravating the stress concentration in the weak part, making the weak part easy to rupture, and being able to release the pressure when the pressure in the outer shell reaches a threshold, thereby ensuring the safety of the battery cell in the event of thermal runaway, and being conducive to improving the safety and stability of the battery cell.

[0007] In some embodiments, the weakened portion is formed by providing a groove on the pressure relief mechanism.

[0008] In the above solution, the local thickness of the pressure relief mechanism is reduced by providing the groove to form a weak portion.

[0009] In some embodiments, the thickness of the main body portion and the thickness of the connecting portion are both greater than the thickness of the weak portion.

[0010] In the above solution, the weak part is weaker in strength than the main body and the connecting part, and is more easily damaged, so the pressure of the battery cell can be released in time.

[0011] In some embodiments, the thickness of the connecting portion is B1, and the thickness of the weak portion is W1, wherein 0.1≤W1 / B1≤0.5.

[0012] In the above scheme, when the thickness of the weak portion and the connecting portion is within the above numerical range, the processing accuracy of the weak portion can be improved, thereby improving the thickness uniformity of the weak portion. When the weak portion is subjected to alternating stress, the degree of damage to the weak portion is more uniform, thereby improving the explosion consistency of the battery.

[0013] When W1 / B1 is less than 0.1, the thickness of the weak portion is relatively thin, and the strength of the weak portion is low. This makes the weak portion easily damaged when thermal runaway does not occur in the battery cell. Furthermore, when a weak portion of this thickness is formed, its dimensions fluctuate significantly, and its thickness uniformity is poor. When the weak portion of different battery cells is subjected to alternating stress, the area or degree of fatigue aging may vary, resulting in poor consistency in the explosive pressure relief of different battery cells.

[0014] When W1 / B1>0.5, the thickness of the weak part is relatively thick and the strength of the weak part is high. When the preset pressure value of the battery cell is small, the weak part is not easily destroyed. When the battery cell suffers thermal runaway, the gas inside the battery cell cannot be discharged in time, and the battery cell is prone to expansion or even explosion.

[0015] In some embodiments, projections of the groove and the first recess in a first direction at least partially overlap, and the first direction is perpendicular to a thickness direction of the pressure relief mechanism.

[0016] In the above solution, the groove and the weak part are arranged correspondingly in the thickness direction, and the projection of the groove and the first recess in the first direction at least partially overlaps, which will aggravate the stress concentration in the weak part, making the weak part more easily damaged, and the battery cell can be decompressed in time.

[0017] In some embodiments, the connecting portion has a first outer surface and a first inner surface along the thickness direction of the pressure relief mechanism, the first inner surface faces the electrode assembly; the groove is recessed relative to the first inner surface in a direction away from the electrode assembly; and / or the groove is recessed relative to the first outer surface in a direction toward the electrode assembly.

[0018] In some embodiments, the connecting portion has a first outer surface and a first inner surface along the thickness direction of the pressure relief mechanism, the first inner surface faces the electrode assembly; the first recess is recessed relative to the first inner surface in a direction away from the electrode assembly, and at least a portion of the main body protrudes from the first outer surface.

[0019] In some embodiments, in the thickness direction of the pressure relief mechanism, the thickness of the connecting portion is B1, and the height of the main body is H, wherein H / B1≤2.

[0020] In the above solution, when the thickness of the connecting portion and the main body is within the above numerical range, the height of the main body is moderate and easy to process and shape. While the stress concentration at the weak portion is aggravated, the main body can be prevented from interfering with foreign objects outside the battery cell.

[0021] When H / B1>2, the height of the main body is too high and is not easy to process and shape. In addition, the excessively high main body may protrude from the surface of the battery cell and interfere with foreign objects outside the battery cell.

[0022] In some embodiments, the first recess has a bottom wall, the first recess is recessed from the first inner surface along a direction away from the electrode assembly to the bottom wall, and the bottom wall does not extend beyond the first outer surface along the direction away from the electrode assembly.

[0023] In the above scheme, along the thickness direction, as the distance between the bottom wall and the first outer surface decreases, the first recess becomes deeper in the thickness direction, and stress concentration is more likely to form at the connection between the main body corresponding to the position of the first recess and the weak part, and the weak part is more likely to be damaged.

[0024] In some embodiments, the pressure relief mechanism further includes a transition portion, which is disposed around the connecting portion and is used to connect the wall portion and the connecting portion, and a thickness of the transition portion is greater than a thickness of the connecting portion.

[0025] In the above solution, the thickness of the transition section is relatively thicker, which can improve the welding strength of the transition section and prevent distortion or burn-through during welding due to the thin transition section. In addition, the thickness of the connecting section is relatively thinner, which makes it easier for the pressure relief mechanism to rupture when subjected to alternating stress, thereby providing timely pressure relief.

[0026] In some embodiments, the thickness of the connecting portion is B1, and the thickness of the transition portion is B2, wherein B1 / B2≤2 / 3.

[0027] In the above solution, when the thickness of the connecting portion and the transition portion is within this numerical range, the thickness of the connecting portion and the transition portion is moderate, which can meet both the welding strength requirements of the transition portion and the strength requirements of the connecting portion.

[0028] In some embodiments, the connecting portion has a first outer surface and a first inner surface along the thickness direction of the pressure relief mechanism, and the first inner surface faces the electrode assembly; the transition portion has a second outer surface and a second inner surface along the thickness direction of the pressure relief mechanism, and the second inner surface faces the electrode assembly; the second outer surface protrudes from the first outer surface in the direction away from the electrode assembly; and / or, the second inner surface protrudes from the first inner surface in the direction close to the electrode assembly.

[0029] In some embodiments, the body portion protrudes relative to the transition portion in a direction away from the electrode assembly.

[0030] In the above solution, a stepped structure is formed between the main body, the weak part, the connecting part and the transition part. Stress concentration is easily formed in the weak part and the connecting part, which will especially aggravate the stress concentration in the weak part. The weak part is easily damaged, and the battery cell can be decompressed in time.

[0031] In some embodiments, a minimum dimension of the connecting portion along a first direction is greater than 0.1 mm, and the first direction is perpendicular to a thickness direction of the pressure relief mechanism.

[0032] In the above solution, the weak portion is closer to the center of the pressure relief mechanism, the alternating stress on the weak portion is more uniform, and the consistency of fracture in the weak portion is higher.

[0033] In some embodiments, the battery cell further includes a protection sheet attached to an outer surface of the wall portion and covering the pressure relief mechanism.

[0034] In the above solution, the protective sheet can protect the pressure relief mechanism and reduce the risk of external objects accidentally hitting or scratching the pressure relief mechanism, which may cause the pressure relief mechanism to be twisted, deformed, or dented.

[0035] In some embodiments, the housing includes an end cover and a shell, the shell is provided with an opening, and the end cover is used to cover the opening, wherein the wall portion is the end cover.

[0036] In the above solution, when the pressure relief mechanism is actuated to discharge high-temperature and high-pressure substances, it will basically not affect the structure of the end cover.

[0037] In a second aspect, the present application provides a battery comprising a battery cell according to any embodiment of the first aspect.

[0038] In a third aspect, the present application provides an electrical device comprising a battery cell according to an embodiment of the third aspect. The battery cell is used to provide electrical energy.

[0039] In a fourth aspect, according to an embodiment of the present application, a method for manufacturing a battery cell is provided, comprising: providing an end cover, the end cover being provided with a pressure relief mechanism and an electrode terminal, the pressure relief mechanism comprising a weak portion, a main body portion and a connecting portion, the main body portion being located within an area surrounded by the weak portion, the connecting portion being located outside the weak portion and being used to connect the end cover, the main body portion protruding relative to the connecting portion, and the pressure relief mechanism forming a first recess at a position corresponding to the main body portion; providing an electrode assembly; providing a shell having an opening; connecting the electrode assembly to the electrode terminal; placing the electrode assembly into the shell, and then connecting the end cover to the shell to close the opening of the shell; the weak portion being configured to be destroyed to release pressure when the pressure inside the shell reaches a threshold; the main body portion protruding relative to the connecting portion in a direction away from the electrode assembly, and the pressure relief mechanism forming a first recess at a position corresponding to the main body portion on a side facing the electrode assembly.

[0040] In a fifth aspect, according to an embodiment of the present application, a manufacturing system for a battery cell is provided, comprising: a first providing device for providing an end cover, the end cover being provided with a pressure relief mechanism and an electrode terminal, the pressure relief mechanism comprising a weak portion, a main body portion and a connecting portion, the main body portion being located in an area surrounded by the weak portion, the connecting portion being located outside the weak portion and being used to connect the end cover, the main body portion protruding relative to the connecting portion, and the pressure relief mechanism forming a first recess at a position corresponding to the main body portion; a second providing device for providing an electrode assembly; a third providing device for providing a shell having an opening; a first assembling device for connecting the electrode assembly to the electrode terminal; a second assembling device for placing the electrode assembly into the shell, and then connecting the end cover to the shell to close the opening of the shell, wherein the weak portion is configured to be destroyed to release pressure when the pressure inside the shell reaches a threshold; the main body portion protrudes relative to the connecting portion in a direction away from the electrode assembly, and the pressure relief mechanism forming a first recess at a position corresponding to the main body portion on a side facing the electrode assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0042] Figure 1 is a structural schematic diagram of a vehicle according to an embodiment of the present application;

[0043] Figure 2 is a schematic diagram of the exploded structure of a battery according to an embodiment of the present application;

[0044] Figure 3 yes Figure 2 A schematic structural diagram of the battery module shown;

[0045] Figure 4 is a schematic diagram of the exploded structure of a battery cell according to an embodiment of the present application;

[0046] Figure 5 is a schematic cross-sectional structural diagram of a battery cell according to an embodiment of the present application;

[0047] Figure 6 yes Figure 5 A in the middle is an enlarged schematic diagram;

[0048] Figure 7 1 is a schematic diagram of the exploded structure of an end cap assembly of a battery cell according to an embodiment of the present application;

[0049] Figure 8 1 is a schematic top view of the pressure relief mechanism of a battery cell according to an embodiment of the present application;

[0050] Figure 9 is a schematic top view of the pressure relief mechanism of a battery cell according to another embodiment of the present application;

[0051] Figure 10 yes Figure 9 Schematic diagram of the cross-sectional structure along the FF direction;

[0052] Figure 11 yes Figure 10 The enlarged schematic diagram at point I in the middle;

[0053] Figure 12 is a partial cross-sectional schematic diagram of a pressure relief mechanism of a battery cell provided in an alternative embodiment;

[0054] Figure 13 is a partial cross-sectional schematic diagram of a pressure relief mechanism of a battery cell provided in another alternative embodiment;

[0055] Figure 14 is a partial cross-sectional schematic diagram of a pressure relief mechanism of a battery cell provided by yet another alternative embodiment;

[0056] Figure 15 is a partial cross-sectional schematic diagram of a pressure relief mechanism of a battery cell provided in yet another alternative embodiment;

[0057] Figure 16 is a schematic flow chart of a method for manufacturing a battery cell according to an embodiment of the present application;

[0058] Figure 17 FIG. 4 is a schematic block diagram of a battery cell manufacturing system according to an embodiment of the present application.

[0059] In the accompanying drawings, the drawings are not necessarily drawn to scale.

[0060] Among them, the reference numerals in the figures are:

[0061] X, thickness direction; Y, first direction; 1, vehicle; 1a, motor; 1b, controller; 10, battery; 11, bottom shell; 12, top shell; 20, battery; 30, battery cell; 40, outer shell; 41, end cover; 42, shell; 421, opening; 412, through hole; 50, electrode assembly; 51, tab; 60, electrode terminal; 70, adapter; 80, pressure relief mechanism; 81, main body; 82, connecting part; 82a, first outer surface; 82b, first inner surface; 83, weak part; 83c, groove; 84, first recessed part; 841, bottom wall; 85, transition part; 85a, second outer surface; 85b, second inner surface. DETAILED DESCRIPTION

[0062] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0063] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0064] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0065] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0066] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0067] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0068] The term "plurality" used in this application refers to two or more (including two).

[0069] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0070] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0071] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The current collector uncoated with the positive active material layer protrudes from the current collector coated with the positive active material layer. The current collectors uncoated with the positive active material layer, when stacked, serve as the positive electrode tabs. For lithium-ion batteries, for example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector. The current collector uncoated with the negative active material layer protrudes from the current collector coated with the negative active material layer. The current collectors uncoated with the negative active material layer, when stacked, serve as the negative electrode tabs. The negative current collector can be made of copper, and the negative active material can be carbon or silicon, for example. The material of the separator may be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly may be a wound structure or a laminated structure, but the embodiments of the present application are not limited thereto.

[0072] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery safety must also be considered.

[0073] The pressure relief mechanism on a battery cell has a significant impact on battery safety. For example, short circuits or overcharging can cause thermal runaway within the cell, leading to a sudden increase in pressure or temperature. In these situations, the pressure relief mechanism activates to release internal pressure and temperature, preventing explosion or fire.

[0074] A pressure relief mechanism refers to an element or component that is actuated to release the internal pressure or temperature of a battery cell when the internal pressure or temperature reaches a predetermined threshold. The threshold design varies according to different design requirements. The threshold may depend on the material of one or more of the positive electrode plate, negative electrode plate, electrolyte and separator in the battery cell. The pressure relief mechanism can take the form of an explosion-proof valve, an air valve, a pressure relief valve or a safety valve, and can specifically adopt a pressure-sensitive or temperature-sensitive element or structure, that is, when the internal pressure or temperature of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an action or the weak structure provided in the pressure relief mechanism is destroyed, thereby forming an opening or channel for the internal pressure or temperature to be released.

[0075] The "activation" mentioned in this application refers to the action of the pressure relief mechanism or its activation to a certain state, thereby allowing the internal pressure and temperature of the battery cell to be released. The action produced by the pressure relief mechanism may include, but is not limited to: at least a portion of the pressure relief mechanism is ruptured, broken, torn or opened, etc. When the pressure relief mechanism is actuated, the high-temperature and high-pressure substances inside the battery cell will be discharged outward from the actuated part as emissions. In this way, the pressure and temperature of the battery cell can be relieved under controllable pressure or temperature, thereby avoiding potential more serious accidents.

[0076] The emissions from battery cells mentioned in this application include but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0077] After the applicant discovered that during the cycle of the battery cell, the battery cell did not explode and release pressure even when the predetermined conditions for thermal runaway were reached, the applicant analyzed and studied the structure and use environment of the battery cell. During transportation, temperature changes, or charging and discharging of the battery cell, the internal pressure of the battery cell fluctuates alternately, causing the pressure relief mechanism to flip back and forth, that is, the pressure relief mechanism is subjected to the alternating stress generated by the gas inside the battery cell. The applicant found that when the preset pressure value of the battery cell is relatively small, the strength requirement for the pressure relief mechanism is correspondingly low. However, in order to ensure the dimensional accuracy of the pressure relief mechanism, it is necessary to maintain a certain strength of the pressure relief mechanism. In this way, even if it is subjected to the alternating stress generated by the gas inside the battery cell, it is not easy to cause fatigue deformation or fracture. Even when the internal pressure of the battery cell exceeds the preset pressure value, the pressure relief mechanism will still not rupture, and the battery cell cannot be vented in time, causing safety hazards.

[0078] Based on the above problems discovered by the applicant, the applicant has improved the structure of the battery cell. The technical solutions described in the embodiments of this application are applicable to the battery cell, the battery containing the battery cell, and the electrical device using the battery.

[0079] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may be fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0080] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0081] like Figure 1 As shown, a battery 10 is provided inside the vehicle 1. The battery 10 can be provided at the bottom, head, or tail of the vehicle 1. The battery 10 can be used to power the vehicle 1, for example, the battery 10 can serve as an operating power source for the vehicle 1.

[0082] The vehicle 1 may further include a controller 1b and a motor 1a. The controller 1b is used to control the battery 10 to supply power to the motor 1a, for example, to meet the power requirements of the vehicle 1 during starting, navigation, and driving.

[0083] In some embodiments of the present application, the battery 10 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0084] like Figure 2 as well as Figure 3 As shown, the battery 10 includes a battery cell 30 ( Figure 2 (not shown) The battery 10 may further include a case for accommodating the battery cells 30 .

[0085] The box is used to accommodate the battery cells 30 , and the box can have various structural forms.

[0086] In some embodiments, the case may include a bottom shell 11 and a top shell 12. The bottom shell 11 and the top shell 12 cover each other. The bottom shell 11 and the top shell 12 together define a storage space for accommodating the battery cell 30. The bottom shell 11 and the top shell 12 may be hollow structures with one side open. The open side of the bottom shell 11 covers the open side of the top shell 12, forming a case with a storage space. A seal may also be provided between the bottom shell 11 and the top shell 12 to achieve a sealed connection between the bottom shell 11 and the top shell 12.

[0087] In actual use, the bottom shell 11 can cover the top of the top shell 12. The bottom shell 11 can also be called an upper box body, and the top shell 12 can also be called a lower box body.

[0088] The bottom shell 11 and the top shell 12 can be in various shapes, for example, a cylinder, a cuboid, etc. Figure 2 In the embodiment, for example, the bottom shell 11 and the top shell 12 are both rectangular parallelepiped structures.

[0089] In the battery 10, there can be one or more battery cells 30. If there are multiple battery cells 30, the multiple battery cells 30 can be connected in series, in parallel, or in a mixed connection. Mixed connection means that the multiple battery cells 30 are connected both in series and in parallel. The multiple battery cells 30 can be directly connected in series, in parallel, or in a mixed connection, and then the entire battery module 20 is housed in a box. Alternatively, multiple battery cells 30 can be first connected in series, in parallel, or in a mixed connection to form a battery module 20. The multiple battery modules 20 are then connected in series, in parallel, or in a mixed connection to form a single unit and housed in a box.

[0090] In some embodiments, as Figure 3 As shown, in the battery, there are multiple battery cells 30. The multiple battery cells 30 are first connected in series, parallel, or mixed to form a battery module 20. The multiple battery modules 20 are then connected in series, parallel, or mixed to form a whole and accommodated in a box.

[0091] In some embodiments, the multiple battery cells 30 in the battery module 20 may be electrically connected via a busbar component to achieve parallel connection, series connection, or mixed connection of the multiple battery cells 30 in the battery module 20 .

[0092] like Figure 4 As shown, in some embodiments, the battery cell 30 includes a housing 40, an electrode assembly 50, an electrode terminal 60, an insulating member, and a transition member 70. The housing 40 includes a shell 42 and an end cover 41, and the shell 42 has an opening 421. The electrode assembly 50 is accommodated in the shell 42, and the electrode assembly 50 includes a tab 51. The end cover 41 is used to cover the opening 421. The electrode terminal 60 is mounted on the end cover 41. The insulating member is located on the side of the end cover 41 facing the electrode assembly 50. The transition member 70 is used to connect the electrode terminal 60 and the tab 51 so that the tab 51 is electrically connected to the electrode terminal 60.

[0093] The shell 42 can be in various shapes, such as a cylinder, a cuboid, etc. The shape of the shell 42 can be determined according to the specific shape of the electrode assembly 50. For example, if the electrode assembly 50 is a cylindrical structure, the shell 42 can be a cylindrical structure. If the electrode assembly 50 is a cuboid structure, the shell 42 can be a cuboid structure. Figure 4 In the embodiment, the shell 42 and the electrode assembly 50 are both rectangular parallelepiped structures.

[0094] The shell 42 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0095] There may be one or more electrode assemblies 50 housed in the housing 42. Figure 4 In the embodiment, there are two electrode assemblies 50 housed in the housing 42 .

[0096] In some embodiments, the electrode assembly 50 further includes a positive electrode sheet, a negative electrode sheet, and a separator. The electrode assembly 50 may be a wound structure formed by winding the positive electrode sheet, the separator, and the negative electrode sheet. The electrode assembly 50 may also be a laminated structure formed by stacking the positive electrode sheet, the separator, and the negative electrode sheet.

[0097] The positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The separator is located between the positive electrode sheet and the negative electrode sheet, isolating the positive electrode sheet from the negative electrode sheet to reduce the risk of short circuit between the positive and negative electrode sheets.

[0098] The material of the spacer may be PP (polypropylene) or PE (polyethylene).

[0099] The tabs 51 in the electrode assembly 50 are divided into positive tabs and negative tabs. The positive tab is the portion of the positive electrode current collector that is not coated with the positive electrode active material layer. The negative tab is the portion of the negative electrode current collector that is not coated with the negative electrode active material layer.

[0100] In the examples of this application, see Figure 4 and Figure 5 The end cap 41 is used to cover the opening 421 of the housing 42 to form a sealed space for accommodating the electrode assembly 50. The sealed space can also be used to accommodate electrolyte, such as electrolyte. The electrode terminal 60 is an output component for outputting the electrical energy of the battery cell 30, and there can be two electrodes.

[0101] The housing 42 may have one or two openings 421. If the housing 42 has one opening 421, then one end cap 41 may be provided. If the housing 42 has two openings 421, then two end caps 41 may be provided. The two end caps 41 respectively cover the two openings 421, and each end cap 41 may be provided with an electrode terminal 60.

[0102] In some embodiments, as Figure 4As shown, the housing 42 has a single opening 421 and a single end cap 41. Two electrode terminals 60 can be provided in the end cap 41. One electrode terminal 60 is electrically connected to the positive tab of the electrode assembly 50 via an adapter 70. The other electrode terminal 60 is electrically connected to the negative tab of the electrode assembly 50 via another adapter 70.

[0103] In other embodiments, the shell 42 has two openings 421. The two openings 421 are arranged on opposite sides of the shell 42, and there are two end caps 41. The two end caps 41 respectively cover the two openings 421 of the shell 42. In this case, there can be only one electrode terminal 60 on each end cap 41. The electrode terminal 60 on one end cap 41 is electrically connected to one tab (positive tab) of the electrode assembly 50 through a transition component 70; the electrode terminal 60 on the other end cap 41 is electrically connected to the other tab (negative tab) of the electrode assembly 50 through another transition component 70.

[0104] In some embodiments, as Figure 4 As shown, the battery cell 30 may further include a pressure relief mechanism 80. The pressure relief mechanism 80 is mounted on the housing 40. The pressure relief mechanism 80 is used to release the pressure inside the battery cell 30 when the internal pressure or temperature of the battery cell 30 reaches a threshold.

[0105] Illustratively, the pressure relief mechanism 80 may be an explosion-proof valve, an explosion-proof disk, an air valve, a pressure relief valve, a safety valve, or the like.

[0106] See Figures 4 to 7 In some embodiments, the housing 40 of the embodiment of the present application has a wall portion, the wall portion has a through hole 412 , and the pressure relief mechanism 80 covers the through hole 412 .

[0107] In the examples of this application, see Figures 4 to 7 In order to enable the pressure relief mechanism 80 to explode and release pressure in time, an embodiment of the present application provides a battery cell 30, which includes: a shell 40, the shell 40 has a wall portion; an electrode assembly 50, the electrode assembly 50 is accommodated in the shell 40; a pressure relief mechanism 80, the pressure relief mechanism 80 is arranged on the wall portion, the pressure relief mechanism 80 includes a weak portion 83, a main body portion 81 and a connecting portion 82, the weak portion 83 is configured to be destroyed to release pressure when the pressure inside the shell 40 reaches a threshold value, the main body portion 81 is located in the area surrounded by the weak portion 83, the connecting portion 82 is located on the outside of the weak portion 83, and is used to connect the wall portion; the main body portion 81 protrudes in a direction away from the electrode assembly 50 relative to the connecting portion 82, and the pressure relief mechanism 80 is formed with a first recess 84 at a position corresponding to the main body portion 81 on the side facing the electrode assembly 50.

[0108] It should be noted that the electrode assembly 50 of the embodiment of the present application may be a wound electrode assembly, a laminated electrode assembly or an electrode assembly in another form.

[0109] In some embodiments, the electrode assembly 50 is a wound electrode assembly. The positive electrode sheet, negative electrode sheet, and separator are all strip-shaped structures. In the embodiment of the present application, the positive electrode sheet, separator, and negative electrode sheet can be stacked in sequence and wound two or more times to form the electrode assembly 50.

[0110] In other embodiments, the electrode assembly 50 is a laminated electrode assembly. Specifically, the electrode assembly 50 includes a plurality of positive electrode sheets and a plurality of negative electrode sheets, which are alternately stacked, and the stacking direction is parallel to the thickness direction of the positive electrode sheets and the thickness direction of the negative electrode sheets.

[0111] In the embodiment of the present application, the end cover 41 may include a wall portion, that is, the pressure relief mechanism 80 may be provided on the end cover 41; or the housing 40 may include a wall portion, that is, the pressure relief mechanism 80 may be provided on the housing 40. The pressure relief mechanism 80 in the embodiment of the present application is provided on the wall portion. It is understandable that the housing 40 and the pressure relief mechanism 80 may be split structures, that is, the two are independently processed and manufactured and then assembled by mechanical connection. The housing 40 and the pressure relief mechanism 80 may also be an integrally molded structure. For example, the present application may thin a predetermined area of ​​the wall portion to form the pressure relief mechanism 80. For the sake of simplicity, the embodiments described below are described with the end cover 41 as the wall portion.

[0112] The thickness of the end cap 41 is greater than that of the housing 42, making it more rigid than the housing 42. Under the same pressure, the end cap 41 is less likely to deform. During transportation, temperature fluctuations, or charging and discharging, the internal pressure of the battery cell 30 fluctuates. Therefore, when the pressure relief mechanism 80 is installed on the end cap 41, alternating stress acts on the pressure relief mechanism 80, causing it to release high-temperature, high-pressure substances without damaging the structure of the end cap 41.

[0113] In the battery cell 30 of the embodiment of the present application, the weak portion 83 refers to a portion of the pressure relief mechanism 80 that is weaker than the main body 81 and the connecting portion 82 and is easily broken, shattered, torn, or opened. The pressure relief mechanism 80 includes the weak portion 83, the main body 81, and the connecting portion 82. The weak portion 83 is located at the connection between the main body 81 and the connecting portion 82. It can be understood that a predetermined area of ​​the pressure relief mechanism 80 is thinned, and the thinned portion forms the weak portion 83. The two portions separated by the weak portion 83 and connected by the weak portion 83 form the main body 81 and the connecting portion 82. Alternatively, the predetermined area of ​​the pressure relief mechanism 80 is treated with a material so that the strength of the area is weaker than that of other areas. The weak portion 83 is formed in the area with low strength, and the two portions with high strength, separated by the weak portion 83, and connected by the weak portion 83 form the main body 81 and the connecting portion 82.

[0114] The connecting portion may be directly connected to the wall portion, or may be indirectly connected to the wall portion through other portions.

[0115] In some examples, the weak portion can surround the main body in a circle. In other examples, the weak portion can also surround the main body at a certain angle, for example, the weak portion can surround the main body 180°-300°.

[0116] When the preset pressure value of the battery cell 30 is low, the strength requirement for the weak portion 83 is correspondingly lower. However, to ensure the dimensional accuracy of the weak portion 83, it is necessary to maintain a certain strength. During transportation, temperature fluctuations, or charging and discharging, the internal pressure of the battery cell 30 fluctuates alternately, causing the pressure relief mechanism 80 to deform, either bulging away from the electrode assembly 50 or concaving toward the electrode assembly 50. When the pressure relief mechanism 80 alternates between bulging and concaving, the weak portion 83 connected to the main body 81 and the connecting portion 82 is subjected to alternating stresses. To prevent the weak portion 83 from rupturing under the alternating stresses, it is necessary to maintain a certain strength. However, due to the certain strength of the weak portion 83, when the internal pressure of the battery cell 30 exceeds the preset pressure value, the weak portion 83 may not rupture in time. If the internal pressure of the battery cell 30 is too high, the gas inside the battery cell 30 cannot be discharged in time, which may cause the battery cell 30 to swell or even explode.

[0117] In the battery cell 30 of the embodiment of the present application, the main body 81 protrudes in the direction away from the electrode assembly 50 relative to the connecting portion 82, and a sudden cross-section occurs at the weak portion 83, causing stress concentration in the weak portion 83. The pressure relief mechanism 80 is formed with a first recess 84 at a position corresponding to the main body 81 on the side facing the electrode assembly 50, further aggravating the stress concentration in the weak portion 83, making the weak portion 83 easy to rupture, and being able to release pressure when the pressure in the outer shell 40 reaches a threshold, thereby ensuring the safety of the battery cell 30 in the event of thermal runaway, and helping to improve the safety and stability of the battery cell 30.

[0118] In some embodiments, the battery cell 30 further includes a protective sheet 90 . The protective sheet 90 is attached to the outer surface of the wall of the housing 40 and covers the pressure relief mechanism 80 .

[0119] The protective sheet 90 can protect the pressure relief mechanism 80 and reduce the possibility of external objects accidentally hitting or scratching the pressure relief mechanism 80, causing the pressure relief mechanism 80 to be twisted or deformed or dented, thereby affecting the normal fracture and explosion of the weak part 83 of the pressure relief mechanism 80.

[0120] In some examples, the protective sheet 90 is located on the upper side of the end cap and covers the through hole 412. The material of the protective sheet 90 can be plastic such as polyethylene or polypropylene.

[0121] In the battery cell 30 of the embodiment of the present application, the weak portion 83 can be in a curved structure, an annular structure, or other shapes. When the weak portion 83 is an annular or ring-shaped structure, the main body 81 is located within the area enclosed by the weak portion 83, and the connecting portion 82 is located outside the weak portion 83. The connecting portion 82 is used to connect to the wall of the housing 40.

[0122] In some embodiments, the weak portion 83 may be formed by forming a notch, a groove or other structure on the pressure relief mechanism 80 to reduce the local strength of the pressure relief mechanism 80 .

[0123] In some embodiments, see Figures 8 to 15 The weak portion 83 is formed by providing a groove 83c on the pressure relief mechanism 80. The connecting portion 82 has a first outer surface 82a and a first inner surface 82b along the thickness direction X of the pressure relief mechanism 80. The first inner surface 82b faces the electrode assembly 50.

[0124] For example, the groove 83c can be formed by removing material from the pressure relief mechanism 80 by machining, which helps to reduce the processing cost and difficulty. Along the thickness direction X, the weak portion 83 and the groove 83c are arranged correspondingly.

[0125] In some embodiments, see Figure 8 The groove 83c on the pressure relief mechanism 80 is curved, and the weak portion 83 corresponding to the groove 83c is a curved structure. The groove 83c on the pressure relief mechanism 80 is strip-shaped, and the weak portion 83 corresponding to the groove 83c is a strip-shaped structure.

[0126] When the internal pressure of the battery cell 30 alternates between high and low, the weak portion 83 is prone to fatigue aging or rupture. The main body 81 flips over after the weak portion 83 ruptures, thereby releasing the pressure of the battery cell 30 .

[0127] In some embodiments, see Figure 9 The groove 83c on the pressure relief mechanism 80 is annular. The weak portion 83 corresponding to the groove 83c is also annular. The main body 81 is located in the area surrounded by the weak portion 83. The connecting portion 82 is used to connect to the wall portion.

[0128] In some examples, the area enclosed by the groove 83c can be in a racetrack, circular, rectangular, or elliptical shape. When the internal pressure of the battery cell 30 fluctuates between high and low, the weak portion 83 is susceptible to fatigue aging or fracture. After the weak portion 83 fractures, the through hole 412 in the wall is exposed, connecting the battery cell 30 to the external environment, allowing the battery cell 30 to quickly release pressure.

[0129] In some embodiments, the groove 83 c is recessed along the thickness direction X.

[0130] For some examples, see Figure 10 and Figure 11 The groove 83 c is recessed relative to the first outer surface 82 a in a direction toward the electrode assembly 50 .

[0131] For other examples, see Figure 12 The groove 83 c is recessed relative to the first inner surface 82 b in a direction away from the electrode assembly 50 .

[0132] In some further examples, see Figure 13 There are two grooves 83c, one groove 83c is recessed relative to the first inner surface 82b in a direction away from the electrode assembly 50, and the other groove 83c is recessed relative to the first outer surface 82a in a direction toward the electrode assembly 50.

[0133] In some embodiments, see Figure 14 The thickness of the main body 81 and the connecting portion 82 are both greater than the thickness of the weak portion 83. The weak portion 83 is weaker than the main body 81 and the connecting portion 82 and is more easily damaged, thereby timely relieving the pressure of the battery cell 30 when the battery cell thermal runaway occurs.

[0134] In some embodiments, the thickness of the connecting portion 82 is B1, and the thickness of the weak portion 83 is W1, where 0.1≤W1 / B1≤0.5. When the thickness of the weak portion 83 and the connecting portion 82 are within the above numerical ranges, the processing accuracy of the weak portion 83 can be improved, thereby improving the thickness uniformity of the weak portion 83. When the weak portion 83 is subjected to alternating stress, the degree of damage to the weak portion 83 is more uniform, thereby improving the explosion consistency of the battery.

[0135] When W1 / B1 is less than 0.1, the thickness of the weak portion 83 is relatively thin, and the strength of the weak portion 83 is low. Therefore, the weak portion 83 is easily damaged when the battery cell 30 does not experience thermal runaway. Furthermore, when the weak portion 83 is formed at this thickness, its dimensions fluctuate significantly, and its thickness uniformity is poor. When the weak portion 83 of different battery cells 30 is subjected to alternating stress, the areas or extent of fatigue aging may vary, resulting in poor consistency in the explosive pressure relief of different battery cells 30.

[0136] When W1 / B1>0.5, the thickness of the weak portion 83 is relatively thick and the strength of the weak portion 83 is relatively high. When the preset pressure value of the battery cell 30 is small, the weak portion 83 is not easily damaged. When the battery cell 30 suffers from thermal runaway, the gas inside the battery cell 30 cannot be discharged in time, and the battery cell 30 is prone to expansion or even explosion.

[0137] In the battery cell 30 of the embodiment of the present application, see Figure 14 The first recess 84 is recessed relative to the first inner surface 82b in a direction away from the electrode assembly 50. Stress concentration is formed at the weak portion 83, and the weak portion 83 is easily damaged, so that the battery cell 30 can be decompressed in time.

[0138] In some embodiments, the projections of the groove 83c and the first recess 84 in the first direction Y at least partially overlap, and the first direction Y is perpendicular to the thickness direction X of the pressure relief mechanism 80. The groove 83c and the weak portion 83 are correspondingly arranged in the thickness direction X, and the projections of the groove 83c and the first recess 84 in the first direction Y at least partially overlap, which exacerbates stress concentration in the weak portion 83, making the weak portion 83 more susceptible to damage, thereby allowing for timely pressure relief from the battery cell 30.

[0139] In some embodiments, see Figure 14 The first recess 84 is recessed relative to the first inner surface 82b in a direction away from the electrode assembly 50, and at least a portion of the body portion 81 protrudes from the first outer surface 82a. At least a portion of the body portion 81 protrudes from the first outer surface 82a, forming a stepped structure between the body portion 81 and the connecting portion 82. This significantly increases stress at the junction of the body portion 81 and the connecting portion 82. Furthermore, the weak portion 83 located at the junction of the body portion 81 and the connecting portion 82 exacerbates stress concentration at the weak portion 83.

[0140] In some embodiments, see Figure 14 In the thickness direction X of the pressure relief mechanism 80, the thickness of the connecting portion 82 is B1, and the height of the main body 81 is H, where H / B1 ≤ 2. When the thicknesses of the connecting portion 82 and the main body 81 are within the above numerical range, the height of the main body 81 is moderate, making it easier to process and form. This can also prevent interference between the main body 81 and foreign objects outside the battery cell 30, even though stress concentration at the weak portion 83 is increased.

[0141] When H / B1>2, the height of the main body 81 is too high and difficult to process. In addition, the excessively high main body 81 may protrude from the surface of the battery cell 30 and interfere with foreign objects outside the battery cell 30 .

[0142] In some embodiments, see Figure 14The first recess 84 has a bottom wall 841. The first recess 84 is recessed from the first inner surface 82b in a direction away from the electrode assembly 50 to the bottom wall 841. The bottom wall 841 does not extend beyond the first outer surface 82a in the direction away from the electrode assembly 50. Along the thickness direction X, as the distance between the bottom wall 841 and the first outer surface 82a decreases, the first recess 84 becomes deeper in the thickness direction X. This increases the likelihood of stress concentration at the connection between the body portion 81 corresponding to the position of the first recess 84 and the weak portion 83, making the weak portion 83 more susceptible to damage.

[0143] In some embodiments, the pressure relief mechanism 80 of the embodiment of the present application further includes a transition portion 85, see Figure 14 As shown, transition portion 85 surrounds connecting portion 82 and connects the wall portion and connecting portion 82. Transition portion 85 is thicker than connecting portion 82. The relatively thicker transition portion 85 improves the weld strength of transition portion 85 and prevents distortion or burn-through during welding, which might occur if the transition portion 85 were thinner. Furthermore, the relatively thinner connecting portion 82 facilitates rupture of pressure relief mechanism 80 when subjected to alternating stress, providing timely pressure relief.

[0144] In some embodiments, the thickness of the connecting portion 82 is B1, and the thickness of the transition portion 85 is B2, where B1 / B2 ≤ 2 / 3. When the thickness of the connecting portion 82 and the transition portion 85 is within this numerical range, the thickness of the connecting portion 82 and the transition portion 85 is moderate, meeting both the welding strength requirements of the transition portion 85 and the strength requirements of the connecting portion 82.

[0145] It should be noted that the transition portion 85 has a second outer surface 85 a and a second inner surface 85 b along the thickness direction X of the pressure relief mechanism 80 , and the second inner surface 85 b faces the electrode assembly 50 .

[0146] In some embodiments, the second outer surface 85 a protrudes beyond the first outer surface 82 a in a direction away from the electrode assembly 50 .

[0147] In some embodiments, the second inner surface 85 b protrudes from the first inner surface 82 b in a direction approaching the electrode assembly 50 .

[0148] In some embodiments, the second outer surface 85 a protrudes from the first outer surface 82 a in a direction away from the electrode assembly 50 ; and the second inner surface 85 b protrudes from the first inner surface 82 b in a direction approaching the electrode assembly 50 .

[0149] As an example, the thickness of the connecting portion 82 is B1, and the thickness of the transition portion 85 is B2, where B1 / B2 ≤ 2 / 3. When the thickness of the connecting portion 82 and the transition portion 85 is within this numerical range, the thickness of the connecting portion 82 and the transition portion 85 is moderate, meeting both the welding strength of the transition portion 85 and the tear strength of the connecting portion 82.

[0150] In some embodiments, the transition portion 85 and the connecting portion 82 are smoothly connected to each other, thereby preventing the connection between the transition portion 85 and the connecting portion 82 from breaking during the installation process.

[0151] In some embodiments, see Figure 15 Along the thickness direction X, the main body 81 protrudes relative to the transition portion 85, away from the electrode assembly 50. Furthermore, the thickness of the transition portion 85 is greater than that of the connecting portion 82. A stepped structure is formed between the main body 81, the weak portion 83, the connecting portion 82, and the transition portion 85. This easily leads to stress concentration in the weak portion 83 and the connecting portion 82, particularly in the weak portion 83, which can easily damage the weak portion 83 and relieve pressure in the battery cell 30.

[0152] The minimum dimension of the connecting portion 82 in the embodiment of the present application is greater than 0.1 mm along the first direction Y. The weak portion 83 is closer to the center of the pressure relief mechanism 80 , and the alternating stress on the weak portion 83 is more uniform, so the consistency of the fracture of the weak portion 83 is higher.

[0153] See also Figure 16 The present embodiment further provides a method for manufacturing a battery cell 30, which includes:

[0154] An end cap 41 is provided. A pressure relief mechanism 80 and an electrode terminal 60 are provided on the end cap 41. The pressure relief mechanism 80 includes a weakened portion 83, a main body 81, and a connecting portion 82. The main body 81 is located within an area surrounded by the weakened portion 83. The connecting portion 82 is located outside the weakened portion 83 and is used to connect to the end cap 41. The main body 81 protrudes relative to the connecting portion 82. The pressure relief mechanism 80 has a first recess 84 formed at a position corresponding to the main body 81.

[0155] Providing an electrode assembly 50;

[0156] Providing a housing 42 having an opening 421;

[0157] Connecting the electrode assembly 50 to the electrode terminal 60;

[0158] The electrode assembly 50 is placed in the housing 42, and then the end cap 41 is connected to the housing 42 to close the opening 421 of the housing 42.

[0159] Among them, the weak portion 83 is configured to be destroyed to release the pressure when the pressure inside the shell 42 reaches a threshold value; the main body 81 protrudes in the direction away from the electrode assembly 50 relative to the connecting portion 82, and the pressure relief mechanism 80 forms a first recess 84 at a position corresponding to the main body 81 on the side facing the electrode assembly 50.

[0160] In the battery cell 30 manufactured by the manufacturing method of the battery cell 30 of the embodiment of the present application, the main body 81 of the pressure relief mechanism 80 protrudes in the direction away from the electrode assembly 50 relative to the connecting portion 82, causing stress concentration at the weak portion 83, and the pressure relief mechanism 80 is formed with a first recess 84 at a position corresponding to the main body 81 on the side facing the electrode assembly 50, thereby aggravating the stress concentration at the weak portion 83, reducing the strength of the weak portion 83, making the weak portion 83 easy to rupture, and being able to release pressure when the pressure in the outer shell 40 reaches a threshold, thereby ensuring the safety of the battery cell 30 in the event of thermal runaway, and helping to improve the safety and stability of the battery.

[0161] The method for manufacturing the battery cell 30 according to the embodiment of the present application can manufacture the battery cell 30 according to the above-mentioned embodiment.

[0162] See also Figure 17 The present embodiment further provides a manufacturing system 1000 for a battery cell 30, which includes:

[0163] A first providing device 1001 is used to provide an end cap 41. The end cap 41 is provided with a pressure relief mechanism 80 and an electrode terminal 60. The pressure relief mechanism 80 includes a weakened portion 83, a main body 81, and a connecting portion 82. The main body 81 is located within the area surrounded by the weakened portion 83. The connecting portion 82 is located outside the weakened portion 83 and is used to connect to the end cap 41. The main body 81 protrudes relative to the connecting portion 82. The pressure relief mechanism 80 has a first recess 84 formed at a position corresponding to the main body 81.

[0164] A second providing device 1002 is used to provide an electrode assembly 50;

[0165] A third providing device 1003 is used to provide a housing 42 having an opening 421;

[0166] The first assembly device 1004 is used to connect the electrode assembly 50 to the electrode terminal 60;

[0167] The second assembly device 1005 is used to place the electrode assembly 50 into the shell 42, and then connect the end cap 41 to the shell 42 to close the opening 421 of the shell 42.

[0168] Among them, the weak portion 83 is configured to be destroyed to release the pressure when the pressure inside the shell 42 reaches a threshold value; the main body 81 protrudes in the direction away from the electrode assembly 50 relative to the connecting portion 82, and the pressure relief mechanism 80 forms a first recess 84 at a position corresponding to the main body 81 on the side facing the electrode assembly 50.

[0169] In the battery cell 30 manufactured by the manufacturing method of the battery cell 30 of the embodiment of the present application, the main body 81 of the pressure relief mechanism 80 protrudes in the direction away from the electrode assembly 50 relative to the connecting portion 82, causing stress concentration at the weak portion 83, and the pressure relief mechanism 80 is formed with a first recess 84 at a position corresponding to the main body 81 on the side facing the electrode assembly 50, thereby aggravating the stress concentration at the weak portion 83, reducing the strength of the weak portion 83, making the weak portion 83 easy to rupture, and being able to release pressure when the pressure in the outer shell 40 reaches a threshold, thereby ensuring the safety of the battery cell 30 in the event of thermal runaway, and helping to improve the safety and stability of the battery.

[0170] The manufacturing system of the battery cell 30 according to the embodiment of the present application can execute the manufacturing method of the battery cell 30 according to the above-mentioned embodiment.

[0171] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A battery cell, comprising: a housing having a wall portion; an electrode assembly, the electrode assembly being accommodated in the housing; a pressure relief mechanism, independently processed and formed and connected to the wall portion, the pressure relief mechanism comprising a weakened portion, a main body portion, a connecting portion, and a transition portion, the weakened portion being configured to be destroyed to release the pressure when the pressure inside the housing reaches a threshold value, the main body portion being located within an area enclosed by the weakened portion, the connecting portion being located outside the weakened portion, the transition portion being disposed around the connecting portion and used to connect the wall portion and the connecting portion, and the thickness of the transition portion being greater than the thickness of the connecting portion; The main body protrudes in a direction away from the electrode assembly relative to the connecting portion, and the pressure relief mechanism is formed with a first recess at a position corresponding to the main body on a side facing the electrode assembly, wherein the first recess has a bottom wall; The connecting portion has a first inner surface along the thickness direction of the pressure relief mechanism, the first inner surface faces the electrode assembly; the transition portion has a second inner surface along the thickness direction of the pressure relief mechanism, the second inner surface faces the electrode assembly; the weak portion has a third inner surface along the thickness direction of the pressure relief mechanism, the third inner surface faces the electrode assembly; along the thickness direction of the pressure relief mechanism, the first inner surface is farther from the electrode assembly than the second inner surface, a first step is formed between the first inner surface and the second inner surface; the bottom wall is farther from the electrode assembly than the third inner surface, and a second step is formed between the third inner surface and the bottom wall; the bottom wall, the second step, the third inner surface, the first inner surface, the first step, and the second inner surface are continuously arranged; The thickness of the connecting portion is B1, and the thickness of the transition portion is B2, wherein B1 / B2≤2 / 3.

2. The battery cell according to claim 1, wherein: The weak portion is formed by providing a groove on the pressure relief mechanism.

3. The battery cell according to claim 2, wherein: The thickness of the main body portion and the thickness of the connecting portion are both greater than the thickness of the weak portion.

4. The battery cell according to claim 3, wherein: The thickness of the connecting portion is B1, and the thickness of the weak portion is W1, wherein 0.1≤W1 / B1≤0.

5.

5. The battery cell according to claim 2, wherein: The connecting portion has a first outer surface along a thickness direction of the pressure relief mechanism, and the groove is recessed relative to the first outer surface along a direction toward the electrode assembly. The battery cell according to claim 1 , wherein: The connecting portion has a first outer surface along the thickness direction of the pressure relief mechanism, and at least a portion of the main body protrudes from the first outer surface.

7. The battery cell according to claim 6, wherein: In the thickness direction of the pressure relief mechanism, the thickness of the connecting portion is B1, and the height of the main body is H, wherein H / B1≤2.

8. The battery cell according to claim 6, wherein: The bottom wall does not extend beyond the first outer surface in a direction away from the electrode assembly.

9. The battery cell according to claim 1, wherein: The connecting portion has a first outer surface along the thickness direction of the pressure relief mechanism; The transition portion has a second outer surface along the thickness direction of the pressure relief mechanism; The second outer surface protrudes from the first outer surface in a direction away from the electrode assembly.

10. The battery cell according to claim 1 or 9, wherein: The main body portion protrudes relative to the transition portion in a direction away from the electrode assembly.

11. The battery cell according to any one of claims 1 to 9, wherein: The battery cell further includes a protection sheet attached to an outer surface of the wall portion and covering the pressure relief mechanism.

12. The battery cell according to any one of claims 1 to 9, wherein: The housing includes an end cover and a shell, the shell is provided with an opening, and the end cover is used to cover the opening. Wherein, the wall portion is the end cover.

13. A battery comprising the battery cell according to any one of claims 1 to 12.

14. An electrical device comprising the battery according to claim 13, wherein the battery is used to provide electrical energy.

15. A method for manufacturing a battery cell, comprising: An end cap is provided, wherein the end cap is provided with a pressure relief mechanism and an electrode terminal, the pressure relief mechanism comprising a weakened portion, a main body portion, a connecting portion, and a transition portion, the main body portion being located within an area surrounded by the weakened portion, the connecting portion being located outside the weakened portion, and the pressure relief mechanism having a first recess formed at a position corresponding to the main body portion; providing an electrode assembly; Providing a housing having a wall portion and an opening, wherein the pressure relief mechanism is independently processed and formed and connected to the wall portion; connecting the electrode assembly to the electrode terminal; placing the electrode assembly into the housing, and then connecting the end cap to the housing to close the opening of the housing, In which, the weak portion is configured to be destroyed to release the pressure when the pressure inside the shell reaches a threshold value; the main body protrudes relative to the connecting portion in a direction away from the electrode assembly, and the pressure relief mechanism forms the first recess at a position corresponding to the main body on the side facing the electrode assembly, the first recess has a bottom wall, the transition portion is arranged around the connecting portion and is used to connect the wall portion and the connecting portion, and the thickness of the transition portion is greater than the thickness of the connecting portion, the connecting portion has a first inner surface along the thickness direction of the pressure relief mechanism, the first inner surface faces the electrode assembly, and the transition portion has a second inner surface along the thickness direction of the pressure relief mechanism, the second inner surface faces the electrode assembly The weak portion has a third inner surface along the thickness direction of the pressure relief mechanism, the third inner surface faces the electrode assembly, and along the thickness direction of the pressure relief mechanism, the first inner surface is farther from the electrode assembly than the second inner surface, a first step is formed between the first inner surface and the second inner surface, the bottom wall is farther from the electrode assembly than the third inner surface, and a second step is formed between the third inner surface and the bottom wall, the bottom wall, the second step, the third inner surface, the first inner surface, the first step and the second inner surface are continuously arranged, the thickness of the connecting portion is B1, and the thickness of the transition portion is B2, wherein B1 / B2≤2 / 3.

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