Battery cell, battery, and electric device

Abstract

The embodiment of the application provides a battery monomer, a battery and an electric equipment, and belongs to the technical field of batteries. The battery monomer comprises a shell, an electrode assembly, a current collecting member and a pressure relief mechanism. The electrode assembly is arranged in the shell. The end cover is used for covering the opening of the shell. The current collecting member is used for connecting the electrode assembly and the end cover. The pressure relief mechanism is arranged on the end cover. The side of the end cover away from the electrode assembly is provided with a recess, the recess is used for accommodating at least part of the pressure relief mechanism, the end cover is provided with a connecting portion in the area where the recess is arranged, the connecting portion is used for being welded with the current collecting member and forming a first welding portion, and the pressure relief mechanism covers the first welding portion along the thickness direction of the end cover. The size of the pressure relief mechanism in the direction perpendicular to the thickness direction of the end cover is not limited by the first welding portion, the size of the recess and the pressure relief mechanism can be increased according to the requirement, the pressure relief capacity of the pressure relief mechanism is improved, and the safety of the battery monomer is improved.

Description

[0001] This application is a divisional application of the invention patent application filed on December 1, 2021, with application number 202180094629.5 and entitled "Battery cell, battery, electrical device and method and apparatus for manufacturing battery cell". Technical Field

[0002] This application relates to the field of energy storage technology, and in particular to a battery cell, a battery, and an electrical device. Background Technology

[0003] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0004] In battery technology, both battery performance and safety must be considered. Therefore, improving battery safety is a pressing issue that needs to be addressed in battery technology. Summary of the Invention

[0005] This application provides a battery cell, a battery, and an electrical device, which can effectively improve the safety of the battery cell.

[0006] In a first aspect, embodiments of this application provide a battery cell, including: a casing having an opening;

[0007] Electrode assembly for housing within the housing;

[0008] End cap, used to cover an opening;

[0009] The current collector is located on the side of the electrode assembly facing the end cap. The current collector is used to connect the electrode assembly and the end cap to achieve electrical connection between the electrode assembly and the end cap.

[0010] The pressure relief mechanism is located on the end cap. The pressure relief mechanism is actuated when the pressure or temperature inside the battery cell reaches a threshold to release the pressure inside the battery cell.

[0011] The end cap has a recess on the side away from the electrode assembly. The recess is used to accommodate at least a part of the pressure relief mechanism. The end cap forms a connecting part in the area where the recess is provided. The connecting part is used to weld with the current collecting component and form a first welding part. The pressure relief mechanism covers the first welding part along the thickness direction of the end cap.

[0012] The pressure relief mechanism includes a base and a pressure relief section. The base is used to weld to the end cap to form a second welded section, and the pressure relief section is used to actuate when the pressure or temperature inside the battery cell reaches a threshold to release the pressure inside the battery cell.

[0013] In the above technical solution, at least a portion of the pressure relief mechanism is housed within the recess of the end cap, reducing the space occupied by the pressure relief mechanism on the outside of the battery cell and resulting in a smaller overall volume of the battery cell. Since the end cap forms a connecting portion in the area where the recess is located, and this connecting portion is welded to the current collector to form a first welded portion, the pressure relief mechanism covers the first welded portion along the thickness direction of the end cap. This allows the pressure relief mechanism and the first welded portion to be distributed along the thickness direction of the end cap. The size of the pressure relief mechanism in the direction perpendicular to the thickness of the end cap is not limited by the first welded portion, and the size of the recess and the pressure relief mechanism can be increased as needed, which is beneficial for improving the pressure relief capacity of the pressure relief mechanism and enhancing the safety of the battery cell.

[0014] In some embodiments, along the thickness direction of the end cap, the surface of the pressure relief portion away from the connecting portion is coplanar with the surface of the base portion away from the connecting portion.

[0015] In the above technical solution, the surface of the pressure relief part away from the connecting part is set to be coplanar with the surface of the base away from the connecting part. In this way, the structure of the outer surface of the pressure relief mechanism is flush, thereby reducing the overall volume of the battery cell and improving the volumetric energy density of the battery cell.

[0016] In some embodiments, the thickness of the pressure relief portion is less than the thickness of the base.

[0017] In the above technical solution, the thickness of the pressure relief part is less than the thickness of the base, making the pressure relief mechanism thinner in the area of ​​the pressure relief part, which facilitates the release of pressure inside the battery cell.

[0018] In some embodiments, the pressure relief section is provided with a groove. When the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief section breaks from the location of the groove to form an opening for the release of internal pressure or temperature of the battery cell.

[0019] In the above technical solution, by setting the groove, it is easier for the pressure relief part to break, thereby improving the effectiveness of the pressure relief part when performing the pressure relief action, and thus effectively improving the safety of the battery cell.

[0020] In some embodiments, the pressure relief mechanism has a relief groove on the side facing the connection portion, the relief groove being used to avoid the first weld portion.

[0021] In the above technical solution, the pressure relief mechanism is provided with a relief groove, which serves to avoid the first welding part, which helps the pressure relief mechanism to abut against the connecting part, making the pressure relief mechanism more stable during the welding process with the end cover and improving the welding quality between the pressure relief mechanism and the end cover.

[0022] In some embodiments, the pressure relief portion and the base together define a clearance groove.

[0023] In the above technical solution, the pressure relief part of the pressure relief mechanism is used to release the pressure inside the battery cell, and the base of the pressure relief mechanism is used to weld and fix it to the end cover. The pressure relief part and the base together define an avoidance groove to avoid the first welded part, so that the area where the avoidance groove is set in the pressure relief mechanism corresponds to the pressure relief part for pressure relief, and the structure is simple.

[0024] In some embodiments, the connecting part is provided with a channel that penetrates two surfaces of the connecting part that are disposed opposite to each other along the thickness direction, and the pressure relief mechanism covers the channel along the thickness direction.

[0025] In the above technical solution, the connecting part is provided with a through-hole, which can release the stress generated when the connecting part is welded to the current collector. The pressure relief mechanism covers the through-hole along the thickness direction of the end cap, and can release the pressure inside the battery cell through the through-hole when the pressure relief mechanism is actuated.

[0026] In some embodiments, the first weld portion extends circumferentially along the channel, the channel being located on the inner circumferential side of the weld portion, and the channel being used to inject electrolyte into the battery cell.

[0027] In the above technical solution, the channel on the connecting part is an electrolyte injection hole, through which electrolyte can be injected into the battery cell.

[0028] In some embodiments, the current collector is provided with a first central hole and a flow channel for the electrolyte to enter the battery cell. The flow channel is disposed around the first central hole and is disposed opposite to the hole along the thickness direction.

[0029] In the above technical solution, the first central hole and the channel are arranged opposite to each other along the thickness direction of the end cap, and the flow channel is arranged around the first central hole. During the process of injecting electrolyte into the battery cell through the channel, the electrolyte can not only flow into the battery cell along the first central hole, but also flow into the battery cell along the flow channel, thereby improving the injection efficiency and allowing the electrolyte to better wet the electrode assembly.

[0030] In some embodiments, the flow channel and the first central hole are independent of each other, or the flow channel and the first central hole are connected to each other.

[0031] In the above technical solution, the arrangement of the flow channel and the first central hole can adapt to the needs of different battery cells, thereby effectively meeting the processing requirements of battery cells.

[0032] In some embodiments, there are multiple flow channels distributed around the first central hole.

[0033] In the above technical solution, the flow channel is designed to facilitate the entry of electrolyte into the electrode assembly to wet the electrode sheet.

[0034] In some embodiments, the flow channel includes a flow-guiding hole that penetrates two surfaces of the flow-collecting member disposed opposite each other along the thickness direction; and / or

[0035] The flow channel includes a flow channel, which is disposed on at least one surface of the flow collecting member in the thickness direction.

[0036] In the above technical solution, the flow channel can be a flow-through hole penetrating both surfaces of the current collector along its thickness direction. Electrolyte entering through the channel can flow rapidly from the side of the current collector facing the end cap to the side away from the end cap through the flow-through hole. Alternatively, the flow channel can be a flow-through groove disposed on the surface of the current collector. Electrolyte entering through the channel can flow laterally along the flow-through groove, which is beneficial for the electrolyte to enter the electrode assembly and wet the electrode sheets.

[0037] In some embodiments, the projection of the second weld portion does not overlap with the projection of the first weld portion along the thickness direction.

[0038] In the above technical solution, the pressure relief mechanism is welded to the end cover to form a second welded part. The second welded part serves to connect the pressure relief mechanism and the end cover, improving the robustness of the pressure relief mechanism positioned behind the end cover. Since the projection of the second welded part along the thickness direction of the end cover does not overlap with the projection of the first welded part along the thickness direction of the end cover, the second welded part will not be formed at the location of the first welded part during the welding process of the pressure relief mechanism and the end cover to form the second welded part. This avoids damage to the first welded part due to secondary welding and ensures the robustness of the connection part after welding with the current collecting component.

[0039] In some embodiments, the first weld portion is a closed structure extending circumferentially along the end cap or a non-closed structure extending circumferentially along the end cap, and the second weld portion is a closed structure extending circumferentially along the end cap or a non-closed structure extending circumferentially along the end cap. The second weld portion is located on the outer periphery of the first weld portion, such that the second weld portion and the first weld portion are offset in the radial direction of the end cap.

[0040] In the above technical solution, since the second welding part is located on the outer periphery of the first welding part, the second welding part is farther away from the channel than the first welding part, thus making the welding position of the pressure relief mechanism and the end cap farther away from the channel. When welding the pressure relief mechanism and the end cap, it is less affected by the residual electrolyte around the channel, ensuring the firmness of the welded pressure relief mechanism and the end cap and improving the welding quality rate.

[0041] In some embodiments, the second weld portion, the first weld portion, and the channel are arranged sequentially from the outside to the inside in the radial direction of the channel.

[0042] Secondly, embodiments of this application provide a battery, comprising: a battery cell provided in any of the embodiments of the first aspect above; and a housing for accommodating the battery cell.

[0043] Thirdly, embodiments of this application provide an electrical device including the battery provided in any of the embodiments of the second aspect above. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0046] Figure 2 This is a schematic diagram of the battery structure provided in some embodiments of this application;

[0047] Figure 3 Exploded views of a single battery cell provided in some embodiments of this application;

[0048] Figure 4 for Figure 3 A cross-sectional view of the battery cell shown;

[0049] Figure 5 Bottom view of a battery cell provided for other embodiments of this application;

[0050] Figure 6 for Figure 4 A partial view of the battery cell shown;

[0051] Figure 7 for Figure 6 The diagram shows the connection between the pressure relief mechanism and the end cap.

[0052] Figure 8 This is a schematic diagram showing the connection between the pressure relief mechanism and the end cap provided in other embodiments of this application;

[0053] Figure 9 for Figure 6 The diagram shows the structure of the current collection component;

[0054] Figure 10 A flowchart illustrating a method for manufacturing a single battery cell according to some embodiments of this application;

[0055] Figure 11 This is a schematic block diagram of a battery cell manufacturing apparatus provided for some embodiments of this application.

[0056] Icons: 10-Box; 11-First part; 12-Second part; 20-Battery cell; 21-Housing shell; 22-Electrode assembly; 221-Positive electrode tab; 222-Negative electrode tab; 223-Second center hole; 23-End cap; 231-Recess; 2311-Bottom surface; 232-Connecting part; 2321-Channel; 233-Cover; 2331-Outer surface; 2332-Inner surface; 234-Protrusion; 2341-Abutting surface; 24-Current collector; 241-First center hole; 242-Current guide channel; 2 5-Pressure relief mechanism; 251-Allowing groove; 252-Base; 253-Pressure relief part; 2531-Scratching groove; 26-Electrode terminal; 27-First welding part; 28-Second welding part; 100-Battery; 200-Controller; 300-Motor; 1000-Vehicle; 2000-Manufacturing equipment; 2100-First supply device; 2200-Second supply device; 2300-Third supply device; 2400-Fourth supply device; 2500-Fifth supply device; 2600-Assembly device; Z-Thickness direction. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0058] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0059] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0060] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0061] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0062] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0063] In this application, "multiple" means two or more (including two).

[0064] In this application, the battery cell 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 are not limited to these. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to these. Battery cells are generally divided into three types according to their packaging method: cylindrical battery cells, square battery cells, and pouch battery cells, and the embodiments of this application are not limited to these.

[0065] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. A battery generally includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0066] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode 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, and the uncoated positive current collector protrudes beyond the coated one, serving as the positive electrode tab. Taking a lithium-ion battery as an 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, etc. The negative electrode 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, and the uncoated negative current collector protrudes beyond the coated one, serving as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together. The separator can be made of PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to these.

[0067] The development of battery technology must take into account multiple design factors, such as energy density, cycle life, discharge capacity, charge / discharge rate and other performance parameters. In addition, battery safety also needs to be considered.

[0068] For individual battery cells, the main safety hazards come from the charging and discharging processes, as well as the appropriate ambient temperature design. To effectively avoid unnecessary losses, battery cells generally have at least three layers of protection. Specifically, these protection measures include at least switching elements, selection of appropriate separator materials, and pressure relief mechanisms. Switching elements are components that stop charging or discharging the battery when the temperature or resistance within the cell reaches a certain threshold. The separator is used to separate the positive and negative electrodes. It can automatically dissolve the micron-sized (or even nanon-sized) micropores attached to it when the temperature rises to a certain value, thus preventing metal ions from passing through the separator and terminating the internal reaction of the battery cell.

[0069] A pressure relief mechanism is a component that is activated to release the internal pressure or temperature of a battery cell when it reaches a predetermined threshold. This threshold design varies depending on design requirements. The threshold may depend on the materials of one or more of the components in the battery cell: the positive electrode, the negative electrode, the electrolyte, and the separator.

[0070] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the pressure and temperature inside the battery cell. The actions of the pressure relief mechanism may include, but are not limited to, at least a portion of the mechanism rupturing, breaking, tearing, or opening. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief within the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.

[0071] For a typical battery cell, the end cap needs to be electrically connected to the electrode assembly so that the end cap serves as an output terminal for the battery cell to output electrical energy. To better achieve the electrical connection between the end cap and the electrode tab, a current collector is usually placed between the electrode assembly and the end cap. The end cap and the electrode assembly are connected through the current collector to achieve the electrical connection between the end cap and the electrode assembly.

[0072] The inventors noted that, to ensure the stability of the current flow between the end cap and the current collector, the end cap and current collector are typically welded together. A welding groove is provided on the outer side of the end cap, and the end cap is welded to the current collector in the area where the welding groove is located to form a welded part. Simultaneously, to ensure the safety of the battery cell, a pressure relief mechanism is generally provided on the end cap. In the direction perpendicular to the thickness of the end cap, the welding groove and the welded part are located on the outer side of the pressure relief mechanism. The pressure relief mechanism is limited in size by the welding groove and the welded part, resulting in insufficient pressure relief capacity. This poor pressure relief capacity means that internal emissions from the battery cell cannot be discharged in time during thermal runaway, easily leading to battery cell explosions, fires, and other phenomena, thus compromising the safety of the battery cell.

[0073] Based on the above considerations, in order to solve the problem of poor safety of battery cells, the inventors have conducted in-depth research and designed a battery cell that has a recess on the side of the end cap away from the electrode assembly. The recess is used to accommodate at least a part of the pressure relief mechanism. The end cap forms a connecting part in the area where the recess is provided. The connecting part is used to weld with the current collector to form a first welding part. The pressure relief mechanism covers the first welding part along the thickness direction of the end cap.

[0074] In such a battery cell, the end cap forms a connecting part in the area where the recess is set. The connecting part is welded to the current collector to form a first welded part. The pressure relief mechanism covers the first welded part along the thickness direction of the end cap, so that the pressure relief mechanism and the first welded part are distributed in the thickness direction of the end cap. The size of the pressure relief mechanism in the direction perpendicular to the thickness of the end cap is not limited by the first welded part. The size of the recess and the pressure relief mechanism can be made larger as needed, which is beneficial to improve the pressure relief capacity of the pressure relief mechanism and improve the safety of the battery cell.

[0075] The technical solutions described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0076] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0077] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0078] Please refer to Figure 1 , Figure 1 The diagram below illustrates the structure of a vehicle 1000 according to some embodiments of this application. A battery 100 is disposed inside the vehicle 1000, and the battery 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000.

[0079] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0080] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0081] Please refer to Figure 2 , Figure 2 The present invention provides a schematic diagram of the structure of a battery 100 according to some embodiments. The battery 100 includes a housing 10 and a battery cell 20. The housing 10 is used to house the battery cell 20.

[0082] The housing 10 is a component that houses the battery cell 20, providing a space for the battery cell 20. The housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first part 11 and a second part 12, which overlap each other to define a space for accommodating the battery cell 20. The first part 11 and the second part 12 can have various shapes, such as a cuboid or a cylinder. The first part 11 can be a hollow structure open on one side, and the second part 12 can also be a hollow structure open on one side, with the open side of the second part 12 overlapping the open side of the first part 11, thus forming a housing 10 with a accommodating space. Alternatively, the first part 11 can be a hollow structure open on one side, and the second part 12 can be a plate-like structure, with the second part 12 overlapping the open side of the first part 11, thus forming a housing 10 with a accommodating space. The first part 11 and the second part 12 can be sealed using a sealing element, such as a sealing ring or sealant.

[0083] In battery 100, there can be one or more battery cells 20. If there are multiple battery cells 20, they can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel. Alternatively, multiple battery cells 20 can be first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed manner to form a whole, which is then housed within the housing 10. Another option is that all battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the whole consisting of all battery cells 20 is housed within the housing 10.

[0084] In some embodiments, the battery 100 may further include a busbar component, through which multiple battery cells 20 can be electrically connected to each other, enabling series, parallel, or mixed connection of the multiple battery cells 20. The busbar component may be a metallic conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0085] Please refer to Figure 3 , Figure 3 The exploded view of a battery cell 20 provided in some embodiments of this application shows that the battery cell 20 includes a housing 21, an electrode assembly 22, an end cap 23, a current collector 24, and a pressure relief mechanism 25.

[0086] The housing 21 is a component used to house the electrode assembly 22. The housing 21 can be a hollow structure with an opening at one end and an internal cavity for housing the electrode assembly 22, or it can be a hollow structure with openings at both opposite ends and an internal cavity for housing the electrode assembly 22. The housing 21 can have various shapes, such as a cylinder or a cuboid. The housing 21 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy.

[0087] Electrode assembly 22 is the component in the battery cell 20 where the electrochemical reaction occurs. Electrode assembly 22 may include a positive electrode, a negative electrode, and a separator. Electrode assembly 22 can be a wound structure formed by winding the positive electrode, separator, and negative electrode, or a stacked structure formed by arranging the positive electrode, separator, and negative electrode in layers. Electrode assembly 22 has a positive electrode tab 221 and a negative electrode tab 222 (…). Figure 3 (Not shown), the positive electrode tab 221 can be the part of the positive electrode sheet that is not coated with the positive active material layer, and the negative electrode tab 222 can be the part of the negative electrode sheet that is not coated with the negative active material layer.

[0088] End cap 23 is a component that closes onto the opening of housing 21 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 23 can be adapted to the shape of housing 21. For example, if housing 21 is a cuboid structure, end cap 23 can be a rectangular plate structure adapted to housing 21; or if housing 21 is a cylindrical structure, end cap 23 can be a circular plate structure adapted to housing 21. The material of end cap 23 can also be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. The material of end cap 23 can be the same as or different from the material of housing 21.

[0089] In the battery cell 20, there can be one or two end caps 23, and the number of end caps 23 can be determined according to the specific structure of the housing 21. For example, if the housing 21 is a hollow structure with an opening at one end, one end cap 23 can be provided accordingly; or if the housing 21 is a hollow structure with openings at both opposite ends, two end caps 23 can be provided accordingly, with the two end caps 23 respectively covering the two openings of the end cap 23.

[0090] The current collector 24 is a conductor, and can be a metal conductor such as copper, iron, aluminum, steel, or aluminum alloy. In a battery cell 20, there can be one or two current collectors 24. In an embodiment where there is one end cap 23 in the battery cell 20, one current collector 24 can be correspondingly provided, and the electrode assembly 22 can be connected to the end cap 23 via the current collector 24. For example, the positive electrode tab 221 of the electrode assembly 22 is connected to the end cap 23 via the current collector 24, and the negative electrode tab 222 of the electrode assembly 22 is connected to the housing 21, so that the end cap 23 and the housing 21 respectively serve as two output electrodes of opposite polarity in the battery cell 20. In an embodiment where there are two end caps 23 in the battery cell 20, two current collectors 24 can be correspondingly provided, with one current collector 24 corresponding to one end cap 23. For example, as... Figure 3As shown, the positive electrode tab 221 of the electrode assembly 22 is connected to the electrode terminal 26 on one end cap 23 through a current collector 24, and the negative electrode tab 222 of the electrode assembly 22 is connected to another end cap 23 through another current collector 24, so that the electrode terminal 26 of one end cap 23 and the other end cap 23 serve as two output electrodes with opposite polarities of the battery cell 20.

[0091] The pressure relief mechanism 25 is a component that releases pressure inside the battery cell 20. When the pressure or temperature inside the battery cell 20 reaches a threshold, the pressure is released through the pressure relief mechanism 25. The pressure relief mechanism 25 can take the form of an explosion-proof valve, explosion-proof disc, air valve, pressure relief valve, or safety valve, and can specifically adopt pressure-sensitive or temperature-sensitive elements or structures. That is, when the pressure or temperature inside the battery cell 20 reaches a predetermined threshold, the pressure relief mechanism 25 performs an action or a weak structure provided in the pressure relief mechanism 25 is destroyed, thereby forming an opening or channel for the pressure or temperature inside the battery cell 20 to be released.

[0092] Please refer to Figure 4 , Figure 4 for Figure 3 The cross-sectional view of the battery cell 20 shown in this application embodiment provides a battery cell 20, including a housing 21, an electrode assembly 22, an end cap 23, a current collector 24, and a pressure relief mechanism 25. The housing 21 has an opening. The electrode assembly 22 is housed within the housing 21. The end cap 23 closes to the opening. The current collector 24 is located on the side of the electrode assembly 22 facing the end cap 23, and connects the electrode assembly 22 and the end cap 23 to achieve electrical connection between the electrode assembly 22 and the end cap 23. The pressure relief mechanism 25 is disposed on the end cap 23, and is actuated when the pressure or temperature inside the battery cell 20 reaches a threshold value to release the pressure inside the battery cell 20.

[0093] The end cap 23 has a recess 231 on the side opposite to the electrode assembly 22. The recess 231 is used to accommodate at least a part of the pressure relief mechanism 25. The end cap 23 forms a connecting part 232 in the area where the recess 231 is provided. The connecting part 232 is used to weld with the current collector 24 to form a first welding part 27. The pressure relief mechanism 25 covers the first welding part 27 along the thickness direction Z of the end cap 23.

[0094] The pressure relief mechanism 25 is a component that releases the pressure inside the battery cell 20. The pressure relief mechanism 25 and the end cap 23 can be connected in various ways, such as by bonding, welding, or interference fit.

[0095] The current collector 24 is connected to both the end cap 23 and the electrode assembly 22 to achieve an electrical connection between the electrode assembly 22 and the end cap 23. The current collector 24 can connect the end cap 23 to the positive electrode tab 221 of the electrode assembly 22, or it can connect the end cap 23 to the negative electrode tab 222 of the electrode assembly 22. The current collector 24 can be connected to the positive electrode tab 221 or the negative electrode tab 222 in a non-fixed manner, for example, by abutting against the positive electrode tab 221 or the negative electrode tab 222; or the current collector 24 can be connected to the positive electrode tab 221 or the negative electrode tab 222 in a fixed manner, for example, by welding the current collector 24 to the positive electrode tab 221 or the negative electrode tab 222.

[0096] A recess 231 is provided on the side of the end cap 23 facing away from the electrode assembly 22. Understandably, the opening of the recess 231 faces away from the electrode assembly 22. The recess 231 is recessed from the surface of the end cap 23 facing away from the electrode assembly 22 in the direction facing the electrode assembly 22, and the opening of the recess 231 is formed on this surface. The recess 231 can be of various shapes, such as circular or square. The recess 231 provides space for the pressure relief mechanism 25. The pressure relief mechanism 25 can be entirely accommodated within the recess 231, or it can be partially accommodated within the recess 231. For example, in the thickness direction Z of the end cap 23, a portion of the pressure relief mechanism 25 may be located within the recess 231, and a portion may be located outside the recess 231.

[0097] The end cap 23 forms a connecting portion 232 in the area where the recess 231 is provided. The connecting portion 232 is the part of the end cap 23 located at the bottom of the recess 231. It can also be understood that the connecting portion 232 is the remaining part of the end cap 23 in the recess direction of the recess 231 after the recess 231 is provided.

[0098] The first welded part 27 is the part where the connecting part 232 and the current collector 24 are connected together after welding. The area where the connecting part 232 and the current collector 24 are welded together forms the first welded part 27. Taking the connecting part 232 and the current collector 24 as an example of welding by through welding, the first welded part 27 can be the part where the connecting part 232 and the current collector 24 are welded and fused together.

[0099] The pressure relief mechanism 25 covers the first welded part 27 along the thickness direction Z of the end cover 23. That is, the pressure relief mechanism 25 completely covers the first welded part 27 along the thickness direction Z of the end cover 23. It can also be understood that the first welded part 27 is located in the area formed by the projection of the pressure relief mechanism 25 along the thickness direction Z of the end cover 23.

[0100] In this embodiment, at least a portion of the pressure relief mechanism 25 is housed within the recess 231 of the end cap 23, reducing the space occupied by the pressure relief mechanism 25 outside the battery cell 20 and resulting in a smaller overall volume of the battery cell 20. Since the end cap 23 forms a connecting portion 232 in the area where the recess 231 is located, and the connecting portion 232 is welded to the current collector 24 to form a first weld portion 27, the pressure relief mechanism 25 covers the first weld portion 27 along the thickness direction Z of the end cap 23. This allows the pressure relief mechanism 25 and the first weld portion 27 to be distributed along the thickness direction Z of the end cap 23. The size of the pressure relief mechanism 25 in the direction perpendicular to the thickness direction Z of the end cap 23 is not limited by the first weld portion 27, allowing the size of the recess 231 and the pressure relief mechanism 25 to be increased as needed. This improves the pressure relief capacity of the pressure relief mechanism 25 and enhances the safety of the battery cell 20.

[0101] In some embodiments, please continue to refer to Figure 4 The pressure relief mechanism 25 is welded to the end cap 23 to form a second welded part 28. Along the thickness direction Z of the end cap 23, the projection of the second welded part 28 does not overlap with the projection of the first welded part 27.

[0102] The second welded part 28 is the portion that connects the pressure relief mechanism 25 and the end cap 23 after welding. The area where the pressure relief mechanism 25 and the end cap 23 form a weld mark is the second welded part 28. Taking the pressure relief mechanism 25 and the end cap 23 as examples of welding by through welding, the second welded part 28 can be the portion where the connection part 232 of the pressure relief mechanism 25 and the end cap 23 are welded together; taking the pressure relief mechanism 25 and the end cap 23 as examples of welding by seam welding, the second welded part 28 can be the solder connecting the outer peripheral surface of the pressure relief mechanism 25 and the inner peripheral surface of the recess 231.

[0103] In this embodiment, the pressure relief mechanism 25 is welded to the end cap 23 to form a second welded portion 28. The second welded portion 28 serves to connect the pressure relief mechanism 25 and the end cap 23, improving the robustness of the pressure relief mechanism 25 after being placed behind the end cap 23. Since the projection of the second welded portion 28 along the thickness direction Z of the end cap 23 does not overlap with the projection of the first welded portion 27 along the thickness direction Z of the end cap 23, the second welded portion 28 will not be formed at the location of the first welded portion 27 during the welding process of the pressure relief mechanism 25 and the end cap 23 to form the second welded portion 28. This avoids damage to the first welded portion 27 due to secondary welding and ensures the robustness of the connection portion 232 after welding with the current collecting member 24.

[0104] In some embodiments, please continue to refer to Figure 4 Both the first welded portion 27 and the second welded portion 28 extend circumferentially along the end cap 23, with the second welded portion 28 located on the outer periphery of the first welded portion 27.

[0105] The first welded portion 27 can be a closed structure extending circumferentially along the end cap 23, for example, the first welded portion 27 is an annular structure. Alternatively, the first welded portion 27 can be a non-closed structure extending circumferentially along the end cap 23, for example, the first welded portion 27 is divided into multiple segments, which are spaced apart circumferentially along the end cap 23. The second welded portion 28 can be a closed structure extending circumferentially along the end cap 23, for example, the second welded portion 28 is an annular structure. Alternatively, the second welded portion 28 can be a non-closed structure extending circumferentially along the end cap 23, for example, the second welded portion 28 is divided into multiple segments, which are spaced apart circumferentially along the end cap 23.

[0106] The second weld portion 28 is located on the outer periphery of the first weld portion 27, such that the second weld portion 28 and the first weld portion 27 are radially offset in the end cap 23. Figure 4 As shown, taking the example that both the first welding part 27 and the second welding part 28 are annular structures, the second welding part 28 is located on the outer periphery of the first welding part 27, so that the first welding part 27 is the inner ring and the second welding part 28 is the outer ring.

[0107] In this embodiment, the second welding part 28 is located on the outer periphery of the first welding part 27, so that the projection of the second welding part 28 along the thickness direction Z of the end cover 23 does not overlap with the projection of the first welding part 27 along the thickness direction Z of the end cover 23. Furthermore, the second welding part 28 has a larger circumferential dimension in the end cover 23, thereby improving the robustness of the pressure relief mechanism 25 after welding with the end cover 23.

[0108] In other embodiments, please refer to Figure 5 , Figure 5 This is a bottom view of the battery cell 20 provided in some other embodiments of this application. Along the circumference of the end cap 23, the second welded portion 28 and the first welded portion 27 are arranged alternately. This ensures that the projection of the second welded portion 28 along the thickness direction Z of the end cap 23 does not overlap with the projection of the first welded portion 27 along the thickness direction Z of the end cap 23, resulting in a simple arrangement.

[0109] The second weld portion 28 and the first weld portion 27 are arranged alternately, such that the first weld portion 27 and the second weld portion 28 are staggered in the circumferential direction of the end cap 23. There can be one first weld portion 27 and multiple second weld portions 28. For example, in... Figure 5 In the middle, there are two first welding parts 27 and two second welding parts 28.

[0110] For example, both the first welded portion 27 and the second welded portion 28 are V-shaped.

[0111] In some embodiments, please refer to Figure 6 , Figure 6 for Figure 4The partial view of the battery cell 20 shown shows that the pressure relief mechanism 25 has a relief groove 251 on the side facing the connection part 232. The relief groove 251 is used to avoid the first welding part 27.

[0112] The clearance groove 251 is a clearance space on the pressure relief mechanism 25 that avoids the first welded portion 27. The clearance groove 251 can accommodate the portion of the first welded portion 27 that protrudes from the connecting portion 232. The clearance groove 251 can be circular, square, etc. For example, the first welded portion 27 is annular, and the clearance groove 251 is a circular structure coaxially arranged with the first welded portion 27.

[0113] It should be noted that whether the first welding part 27 and the second welding part 28 are offset radially or circumferentially in the end cover 23, an avoidance groove 251 for avoiding the first welding part 27 can be provided on the side of the pressure relief mechanism 25 facing the connecting part 232.

[0114] In this embodiment, the clearance groove 251 serves to avoid the first welding part 27, which helps the pressure relief mechanism 25 to abut against the connecting part 232, making the pressure relief mechanism 25 more stable during the welding process with the end cover 23 and improving the welding quality between the pressure relief mechanism 25 and the end cover 23.

[0115] In some embodiments, please refer to Figure 7 , Figure 7 for Figure 6 The diagram shows the connection between the pressure relief mechanism 25 and the end cap 23. The pressure relief mechanism 25 includes a base 252 and a pressure relief portion 253. The base 252 is used to weld to the end cap 23 to form a second welded portion 28. The pressure relief portion 253 is used to actuate when the pressure or temperature inside the battery cell 20 reaches a threshold to release the pressure inside the battery cell 20. The pressure relief portion 253 is connected to the inner peripheral surface of the base 252 and covers the first welded portion 27 along the thickness direction Z of the end cap 23. The pressure relief portion 253 and the base 252 together define a relief groove 251.

[0116] The base 252 is the part welded to the end cap 23 for the pressure relief mechanism 25, and the pressure relief part 253 is the part of the pressure relief mechanism 25 that releases the pressure inside the battery cell 20. The base 252 and the pressure relief part 253 can be an integrally formed structure.

[0117] For example, the pressure relief mechanism 25 is a circular explosion-proof plate, the base 252 is an annular structure, and the pressure relief part 253 is a circular structure. The outer peripheral surface of the pressure relief part 253 is connected to the inner peripheral surface of the base 252. The inner peripheral surface of the base 252 refers to the surface located inside the base 252 and extending along the thickness direction Z of the end cap 23. Taking the base 252 as an annular shape as an example, the inner peripheral surface of the base 252 is the circular surface inside the base 252.

[0118] The clearance groove 251 is defined by the pressure relief part 253 and the base 252. The side surface of the clearance groove 251 is the inner circumferential surface of the base 252, and the bottom surface 2311 of the clearance groove 251 is the surface of the pressure relief part 253 facing the connecting part 232.

[0119] When the pressure or temperature inside the battery cell 20 reaches a threshold, the pressure relief section 253 can be actuated by rupturing, breaking, tearing, or opening. For example, in... Figure 7 In the middle, the pressure relief part 253 is provided with a groove 2531. When the internal pressure or temperature of the battery cell 20 reaches a threshold, the pressure relief part 253 breaks from the position of the groove 2531 to form an opening for the pressure or temperature inside the battery cell 20 to be released.

[0120] In this embodiment, the pressure relief part 253 and the base part 252 together define an avoidance groove 251 that avoids the first welding part 27, so that the area where the avoidance groove 251 is provided in the pressure relief mechanism 25 is correspondingly formed with a pressure relief part 253 for pressure relief. The structure is simple and is conducive to the pressure relief mechanism 25 releasing the pressure inside the battery cell 20.

[0121] In some embodiments, please continue to refer to Figure 7 The thickness of the pressure relief part 253 is less than the thickness of the base part 252.

[0122] The thickness of the pressure relief portion 253 is the dimension of the pressure relief portion 253 in the thickness direction Z of the end cap 23, and the thickness of the base portion 252 is the dimension of the pressure relief portion 253 in the thickness direction Z of the end cap 23.

[0123] For example, along the thickness direction Z of the end cap 23, the surface of the pressure relief portion 253 facing away from the connecting portion 232 is coplanar with the surface of the base portion 252 facing away from the connecting portion 232.

[0124] The thickness of the pressure relief section 253 is less than the thickness of the base 252, making the pressure relief mechanism 25 thinner in the area of ​​the pressure relief section 253, which facilitates the release of pressure inside the battery cell 20. When a groove 2531 is provided on the pressure relief section 253, the depth of the groove 2531 does not need to be too deep to actuate the pressure relief section 253 and release the pressure inside the battery cell 20.

[0125] In some embodiments, please continue to refer to Figure 7 The outer peripheral surface of the base 252 is welded to the inner peripheral surface of the recess 231 to form a second welded portion 28.

[0126] The outer peripheral surface of the base 252 refers to the surface located outside the base 252 and extending along the thickness direction Z of the end cap 23. Taking the base 252 as an example, the outer peripheral surface of the base 252 is the circular surface outside the base 252. The inner peripheral surface of the recess 231 is the surface of the recess 231 extending along the thickness direction Z of the end cap 23.

[0127] The second weld portion 28 is located in the gap area formed between the outer peripheral surface of the base 252 and the inner peripheral surface of the recess 231, so that the second weld portion 28 is far away from the pressure relief portion 253, reducing the risk of damage to the pressure relief portion 253 during the welding of the pressure relief mechanism 25. The pressure relief mechanism 25 can be welded to the end cap 23 by seam welding, which is a simple welding method with high welding efficiency.

[0128] In other embodiments, please refer to Figure 8 , Figure 8 This is a schematic diagram of the connection between the pressure relief mechanism 25 and the end cap 23 provided in some other embodiments of this application. The base 252 is welded to the connecting part 232 to form a second welded part 28.

[0129] The base 252 and the connecting part 232 can be welded together by through welding. The second welding part 28 passes through the base 252 and is combined with the connecting part 232, so that the pressure relief mechanism 25 has good firmness after being welded to the end cover 23.

[0130] In some embodiments, please refer to Figures 6-8 The end cap 23 includes a cap body 233 and a protrusion 234. The cap body 233 is used to connect to the housing 21. The cap body 233 has an outer surface 2331 and an inner surface 2332 that are disposed opposite each other along the thickness direction Z of the end cap 23. The inner surface 2332 faces the flow collecting member 24, and the recess 231 is recessed from the outer surface 2331 in the direction facing the flow collecting member 24. The protrusion 234 protrudes from the inner surface 2332 and is located at a position corresponding to the recess 231 on the cap body 233. The protrusion 234 has an abutment surface 2341 for abutting against the flow collecting member 24. The portion of the end cap 23 located between the abutment surface 2341 and the bottom surface 2311 of the recess 231 is a connecting portion 232.

[0131] The cover 233 is the main body connecting the end cap 23 and the housing 21, and the protrusion 234 is the portion of the end cap 23 that protrudes from the cover 233. The cover 233 can be a plate-like structure, and the protrusion 234 can be a boss provided on the inner surface 2332 of the cover 233. The inner surface 2332 of the cover 233 is the surface of the cover 233 facing the current collector 24 along the thickness direction Z of the end cap 23, and the outer surface 2331 of the cover 233 is the surface of the cover 233 facing away from the current collector 24 along the thickness direction Z of the end cap 23. The abutting surface 2341 of the protrusion 234 is the end face of the protrusion 234 facing away from the cover 233 along the thickness direction Z of the end cap 23. The bottom surface 2311 of the recess 231 is the surface of the recess 231 that is closest to the current collector 24 along the thickness direction Z of the end cap 23. Along the thickness direction Z of the end cap 23, the bottom surface 2311 of the recess 231 and the abutting surface 2341 of the protrusion 234 are the two surfaces of the connecting part 232.

[0132] In this embodiment, the protrusion 234 is located at the position corresponding to the recess 231 on the cover 233 and protrudes from the inner surface 2332 of the cover 233. The protrusion 234 can reinforce the position where the recess 231 is located on the cover 233 and allow the recess 231 to be recessed as deeply as possible along the direction facing the flow collector 24, which is beneficial to increasing the recess depth of the recess 231. In addition, the protrusion 234 protrudes from the inner surface 2332 of the cover 233, which makes it easier to ensure the flatness of the contact surface 2341, so that the protrusion 234 and the flow collector 24 can maintain good contact and ensure the flow area between the flow collector 24 and the end cap 23.

[0133] In some embodiments, along the thickness direction Z of the end cap 23, the bottom surface 2311 of the recess 231 is closer to the flow collector 24 than the inner surface 2332 of the cover 233; or, the bottom surface 2311 of the recess 231 is flush with the inner surface 2332 of the cover 233.

[0134] If the bottom surface 2311 of the recess 231 is closer to the flow collector 24 than the inner surface 2332 of the cover 233, then the recess 231 is recessed into the protrusion 234; if the bottom surface 2311 of the recess 231 is flush with the inner surface 2332 of the cover 233, then the bottom surface 2311 of the recess 231 and the inner surface 2332 of the cover 233 are located in the same plane.

[0135] The above structure, on the one hand, increases the recess depth of the recess 231, thereby increasing the space in the recess 231 for accommodating the pressure relief mechanism 25; on the other hand, it makes the distance between the abutting surface 2341 of the protrusion 234 and the bottom surface 2311 of the recess 231 relatively small, making the thickness of the connecting part 232 relatively small, which facilitates welding (e.g., through welding) the connecting part 232 to the current collecting member 24 from the outside of the end cover 23, and improves the firmness of the connecting part 232 after welding to the current collecting member 24.

[0136] In some embodiments, the pressure relief mechanism 25 is entirely housed within the recess 231. The pressure relief mechanism 25 has no portion located outside the recess 231, thus not occupying space outside the recess 231 and further reducing the overall volume of the battery cell 20.

[0137] In some embodiments, please continue to refer to Figures 6-8 The connecting part 232 is provided with a channel 2321, which penetrates the two surfaces of the connecting part 232 that are arranged opposite each other along the thickness direction Z of the end cover 23. The pressure relief mechanism 25 covers the channel 2321 along the thickness direction Z of the end cover 23.

[0138] The channel 2321 is a through-hole structure provided in the connecting part 232, and the channel 2321 can be provided at the center of the connecting part 232. In the embodiment where the pressure relief mechanism 25 is provided with the relief groove 251, the channel 2321 communicates with the relief groove 251.

[0139] In an embodiment where the end cap 23 has a protrusion 234, the two surfaces of the connecting portion 232 that are disposed opposite each other along the thickness direction Z of the end cap 23 are the abutting surface 2341 of the protrusion 234 and the bottom surface 2311 of the recess 231.

[0140] In this embodiment, the connecting portion 232 is provided with a channel 2321 that penetrates the connecting portion 232. The channel 2321 can release the stress generated when the connecting portion 232 is welded to the current collector 24. The pressure relief mechanism 25 covers the channel 2321 along the thickness direction Z of the end cap 23. When the pressure relief mechanism 25 is actuated, the pressure inside the battery cell 20 can be released through the channel 2321.

[0141] In some embodiments, the first weld portion 27 extends circumferentially along the channel 2321, which is located on the inner circumferential side of the weld portion. The channel 2321 is used to inject electrolyte into the battery cell 20. Electrolyte can be injected into the battery cell 20 through the channel 2321.

[0142] The first weld portion 27 can be a closed structure extending circumferentially along the end cap 23, for example, the first weld portion 27 can be an annular structure. The first weld portion 27 can also be a non-closed structure extending circumferentially along the end cap 23, for example, the first weld portion 27 can be divided into multiple segments, which are arranged at intervals along the circumference of the end cap 23. Taking the first weld portion 27 as an annular structure as an example, the first weld portion 27 can be coaxially arranged with the channel 2321, so that the channel 2321 is located on the inner circumferential side of the first weld portion 27.

[0143] When both the first weld portion 27 and the second weld portion 28 extend circumferentially along the end cap 23, and the second weld portion 28 is located on the outer periphery of the first weld portion 27, the second weld portion 28, the first weld portion 27, and the channel 2321 are arranged sequentially from the outside to the inside in the radial direction of the channel 2321, that is, the second weld portion 28 is located on the outer periphery of the first weld portion 27, and the first weld portion 27 is located on the outer periphery of the channel 2321.

[0144] When electrolysis is injected into the battery cell 20 through the channel 2321, electrolyte may remain around the connection portion 232. If the welding position is close to the channel 2321 during the welding of the pressure relief mechanism 25 and the end cap 23, the residual electrolyte on the connection portion 232 may cause the weld between the pressure relief mechanism 25 and the end cap 23 to be weak, resulting in a low welding yield. However, since the second welding portion 28 is located on the outer periphery of the first welding portion 27, it is further away from the channel 2321 than the first welding portion 27. This allows the welding position of the pressure relief mechanism 25 and the end cap 23 to be further away from the channel 2321. Therefore, the welding of the pressure relief mechanism 25 and the end cap 23 is less affected by the residual electrolyte around the channel 2321, ensuring the strength of the weld and improving the welding yield.

[0145] In some embodiments, please refer to Figure 9 , Figure 9 for Figure 6 The schematic diagram of the current collector 24 shown shows that the current collector 24 is provided with a first central hole 241 for the electrolyte to enter the battery cell 20 and a flow channel 242. The flow channel 242 is arranged around the first central hole 241 along the thickness direction Z of the end cap 23. The first central hole 241 and the channel 2321 are arranged opposite to each other.

[0146] The first central hole 241 is a through hole located at the center of the flow collecting member 24. Taking the flow collecting member 24 as a disk structure as an example, the axis of the first central hole 241 coincides with the axis of the flow collecting member 24. The first central hole 241 and the channel 2321 are arranged opposite each other along the thickness direction Z of the end cap 23. The first central hole 241 and the channel 2321 can be coaxial, or the axis of the first central hole 241 can be slightly deviated from the axis of the channel 2321. As long as the first central hole 241 and the channel 2321 are not completely misaligned in the radial direction of the first central hole 241, it should be understood that the first central hole 241 and the channel 2321 are arranged opposite each other along the thickness direction Z of the end cap 23.

[0147] The flow channel 242 is a channel on the current collecting member 24 that is distinct from the first central hole 241 and used for conveying electrolyte. The flow channel 242 can be independent of or connected to the first central hole 241. There can be one or more flow channels 242. Taking multiple flow channels 242 as an example, multiple flow channels 242 can be distributed around the first central hole 241.

[0148] For example, the electrode assembly 22 has a second central hole 223, and the first central hole 241 is disposed opposite to the second central hole 223 along the thickness direction Z of the end cap 23. Taking the wound structure of the electrode assembly 22, which is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet, as an example, the second central hole 223 is formed at the core position of the main body.

[0149] In this embodiment, since the first central hole 241 and the channel 2321 are arranged opposite to each other along the thickness direction Z of the end cap 23, and the flow channel 242 is arranged around the first central hole 241, during the process of injecting electrolyte into the battery cell 20 through the channel 2321, the electrolyte can not only flow into the battery cell 20 along the first central hole 241, but also flow into the battery cell 20 along the flow channel 242, thereby improving the injection efficiency and allowing the electrolyte to better wet the electrode assembly 22.

[0150] In some embodiments, please continue to refer to Figure 9 The flow channel 242 includes a flow-guiding hole that penetrates two surfaces of the flow-collecting member 24 that are disposed opposite each other along the thickness direction Z of the end cap 23; and / or, the flow channel 242 includes a flow-guiding groove that is disposed on at least one surface of the flow-collecting member 24 in the thickness direction Z of the end cap 23.

[0151] The flow guide groove is provided on at least one surface of the current collector 24 in the thickness direction Z of the end cover 23. It can be that only the surface of the current collector 24 facing the electrode assembly 22 is provided with the flow guide groove, or only the surface of the current collector 24 facing the end cover 23 is provided with the flow guide groove, or both the surface of the current collector 24 facing the end cover 23 and the surface facing the electrode assembly 22 are provided with the flow guide groove.

[0152] In this embodiment, if the flow channel 242 is a flow hole penetrating both surfaces of the current collector 24 along the thickness direction Z of the end cap 23, the electrolyte entering through the channel 2321 can flow rapidly from the side of the current collector 24 facing the end cap 23 to the side away from the end cap 23 through the flow hole. If the flow channel 242 is a flow groove provided on the surface of the current collector 24, the electrolyte entering through the channel 2321 can flow laterally along the flow groove, which is beneficial for the electrolyte to enter the electrode assembly 22 to wet the electrode sheet.

[0153] This application provides a battery 100, including a housing 10 and a battery cell 20 provided in any of the above embodiments, wherein the housing 10 is used to accommodate the battery cell 20.

[0154] This application provides an electrical device, including a battery 100 and any embodiment of the battery 100 provided.

[0155] In addition, please refer to Figure 3 and Figure 4 This application provides a cylindrical battery, including a housing 21, an electrode assembly 22, an end cap 23, a current collector 24, and a pressure relief mechanism 25. The housing 21 has openings at opposite ends. One end cap 23 covers the top opening of the housing 21, and the other end cap 23 covers the bottom opening of the housing 21. The end cap 23 at the top of the housing 21 is provided with electrode terminals 26. The electrode assembly 22 has a positive electrode tab 221 and a negative electrode tab 222. The positive electrode tab 221 is connected to the electrode terminal 26 via a current collector 24, and the negative electrode tab 222 is connected to the end cap 23 at the bottom of the housing 21 via another current collector 24. The pressure relief mechanism 25 is disposed on the end cap 23 at the bottom of the housing 21. The end cap 23 at the bottom of the housing 21 has a recess 231 on the side opposite to the electrode assembly 22. The recess 231 is used to accommodate at least a part of the pressure relief mechanism 25. The end cap 23 at the bottom of the housing 21 forms a connecting part 232 in the area where the recess 231 is provided. The connecting part 232 is used to weld with the current collector 24 to form a first welding part 27. The pressure relief mechanism 25 covers the first welding part 27 along the thickness direction Z of the end cap 23.

[0156] In such a cylindrical battery, since the end cap 23 forms a connecting portion 232 in the area where the recess 231 is provided, the connecting portion 232 is welded to the current collector 24 to form a first weld portion 27, and the pressure relief mechanism 25 covers the first weld portion 27, the pressure relief mechanism 25 and the first weld portion 27 are distributed in the thickness direction Z of the end cap 23. The size of the pressure relief mechanism 25 in the thickness direction Z perpendicular to the end cap 23 is not limited by the first weld portion 27. The size of the recess 231 and the pressure relief mechanism 25 can be made larger as needed, which is beneficial to improve the pressure relief capacity of the pressure relief mechanism 25 and improve the safety of the battery cell 20.

[0157] Please refer to Figure 10 , Figure 10 This is a flowchart illustrating a method for manufacturing a battery cell 20 according to some embodiments of this application. The embodiments of this application provide a method for manufacturing a battery cell 20, the method comprising:

[0158] S100: Provides housing 21 with an opening;

[0159] S200: Provides electrode assembly 22;

[0160] S300: Provides an end cap 23, the end cap 23 having a recess 231, and the end cap 23 forming a connecting portion 232 in the area where the recess 231 is provided; provides a flow collector 24;

[0161] S400: Provides a pressure relief mechanism 25, which is actuated when the pressure or temperature inside the battery cell 20 reaches a threshold to release the pressure inside the battery cell 20.

[0162] S500: The electrode assembly 22 is housed within the housing 21;

[0163] S600: Connect the current collector 24 to the electrode assembly 22;

[0164] S700: Close the end cap 23 to the opening, so that the recess 231 is located on the side of the end cap 23 away from the electrode assembly 22;

[0165] S800: The connecting part 232 is welded to the current collecting member 24 to form the first welded part 27;

[0166] S900: The pressure relief mechanism 25 is installed inside the end cover 23, such that at least a portion of the pressure relief mechanism 25 is accommodated in the recess 231, and the pressure relief mechanism 25 covers the first welded portion 27 along the thickness direction Z of the end cover 23.

[0167] In the above method, the order of steps S100, S200, S300 and S400 is not restricted. For example, step S400 can be executed first, then step S300, then step S200, and then step S100.

[0168] It should be noted that the relevant structure of the battery cell 20 manufactured by the manufacturing method provided in the above embodiments can be found in the battery cell 20 provided in the foregoing embodiments, and will not be repeated here.

[0169] Please refer to Figure 11 , Figure 11 This is a schematic block diagram of a battery cell 20 manufacturing apparatus 2000 provided in some embodiments of this application. This application also provides a battery cell 2000 manufacturing apparatus 2000, which includes a first providing device 2100, a second providing device 2200, a third providing device 2300, a fourth providing device 2400, a fifth providing device 2500, and an assembly device 2600.

[0170] A first providing device 2100 is used to provide a housing 21, having an opening. A second providing device 2200 is used to provide an electrode assembly 22. A third providing device 2300 is used to provide an end cap 23, the end cap 23 having a recess 231, and a connecting portion 232 forming in the area where the recess 231 is provided. A fourth providing device 2400 is used to provide a current collector 24. A fifth providing device 2500 is used to provide a pressure relief mechanism 25, the pressure relief mechanism 25 being actuated when the pressure or temperature inside the battery cell 20 reaches a threshold, to release the pressure inside the battery cell 20. Assembly device 2600 is used to accommodate electrode assembly 22 within housing 21; assembly device 2600 is also used to connect current collector 24 to electrode assembly 22; assembly device 2600 is also used to close end cap 23 to opening, such that recess 231 is located on the side of end cap 23 away from electrode assembly 22; assembly device 2600 is also used to weld connection portion 232 to current collector 24 to form first weld portion 27; assembly device 2600 is also used to install pressure relief mechanism 25 within end cap 23, such that at least a portion of pressure relief mechanism 25 is accommodated in recess 231, such that pressure relief mechanism 25 covers first weld portion 27 along thickness direction Z of end cap 23.

[0171] It should be noted that the relevant structure of the battery cell 20 manufactured by the manufacturing equipment 2000 provided in the above embodiments can be found in the battery cell 20 provided in the foregoing embodiments, and will not be repeated here.

[0172] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0173] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, include: The shell has an opening; Electrode assemblies, for housing within the housing; End cap, for covering the opening; A current collector is located on the side of the electrode assembly facing the end cap. The current collector is used to connect the electrode assembly and the end cap to achieve electrical connection between the electrode assembly and the end cap. A pressure relief mechanism is provided on the end cap. The pressure relief mechanism is actuated when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell. The end cap has a recess on the side opposite to the electrode assembly, the recess is used to accommodate at least a part of the pressure relief mechanism, the end cap forms a connecting part in the area where the recess is provided, the connecting part is used to weld to the current collecting member and form a first welding part, and the pressure relief mechanism covers the first welding part along the thickness direction of the end cap. The pressure relief mechanism includes a base and a pressure relief part. The base is used to weld to the end cap to form a second welded part. The pressure relief part is used to actuate when the pressure or temperature inside the battery cell reaches a threshold to release the pressure inside the battery cell.

2. The battery cell according to claim 1, characterized in that, Along the thickness direction of the end cap, the surface of the pressure relief portion facing away from the connecting portion is coplanar with the surface of the base portion facing away from the connecting portion.

3. The battery cell according to claim 1, characterized in that, The thickness of the pressure relief section is less than the thickness of the base.

4. The battery cell according to claim 3, characterized in that, The pressure relief section is provided with a groove. When the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief section breaks from the groove to form an opening for the pressure or temperature inside the battery cell to be released.

5. The battery cell according to claim 1, characterized in that, The pressure relief mechanism has a clearance groove on the side facing the connection part, and the clearance groove is used to avoid the first welded part.

6. The battery cell according to claim 5, characterized in that, The pressure relief portion and the base together define the clearance groove.

7. The battery cell according to any one of claims 1-6, characterized in that, The connecting part is provided with a channel, which penetrates two surfaces of the connecting part that are arranged opposite to each other along the thickness direction, and the pressure relief mechanism covers the channel along the thickness direction.

8. The battery cell according to claim 7, characterized in that, The first welded portion extends circumferentially along the channel, which is located on the inner circumferential side of the welded portion, and is used to inject electrolyte into the battery cell.

9. The battery cell according to claim 8, characterized in that, The current collector is provided with a first central hole and a flow channel for the electrolyte to enter the battery cell. The flow channel is disposed around the first central hole and is disposed opposite to the channel along the thickness direction.

10. The battery cell according to claim 9, characterized in that, The flow channel is independent of the first central hole, or the flow channel is connected to the first central hole.

11. The battery cell according to claim 9, characterized in that, There are multiple flow channels, and the multiple flow channels are distributed around the first central hole.

12. The battery cell according to claim 9, characterized in that, The flow guiding channel includes a flow guiding hole that penetrates two surfaces of the flow collecting member that are disposed opposite to each other along the thickness direction; and / or The flow channel includes a flow guide groove, which is disposed on at least one surface of the flow collecting member in the thickness direction.

13. The battery cell according to claim 7, characterized in that, Along the thickness direction, the projection of the second welded portion does not overlap with the projection of the first welded portion.

14. The battery cell according to claim 13, characterized in that, The first welded portion is either a closed structure extending circumferentially along the end cap or a non-closed structure extending circumferentially along the end cap. The second welded portion is either a closed structure extending circumferentially along the end cap or a non-closed structure extending circumferentially along the end cap. The second welded portion is located on the outer periphery of the first welded portion, such that the second welded portion and the first welded portion are offset radially from each other in the end cap.

15. The battery cell according to claim 14, characterized in that, The second welding part, the first welding part, and the channel are arranged sequentially from the outside to the inside in the radial direction of the channel.

16. A battery, characterized in that, include: The battery cell as described in any one of claims 1-15; The housing is used to house the individual battery cells.

17. An electrical appliance, characterized in that, Includes the battery as described in claim 16.

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