Battery cell, manufacturing method therefor, battery, and electrical apparatus

Abstract

Provided in the embodiments of the present application are a battery cell, a manufacturing method therefor, a battery and an electrical apparatus, the battery cell comprising a casing (1) comprising a first wall (13); an electrode assembly (3) arranged in the casing (1), the electrode assembly (3) comprising an electrode body (31) and a first tab (32), and the first tab (32) being led out of the electrode body (31); and a first current collecting member (4) for electrically connecting the first tab (32) and the first wall (13), the first current collecting member (4) being connected to the inner surface of the first wall (13) by means of a first weld seam (41), and the first weld seam (41) not penetrating to the outer surface of the first wall (13).

Description

Battery cell and manufacturing method thereof, battery and electric device

[0001] Cross-references to related applications

[0002] This disclosure is based on the Chinese application with application number 202311103985.6 and application date August 30, 2023, and claims its priority. The disclosed content of the above-mentioned Chinese application is hereby introduced into this disclosure as a whole. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a battery cell and a manufacturing method thereof, a battery, and an electrical device. Background Art

[0004] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, power batteries, as the power source of electric vehicles, play an irreplaceable role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also growing. As a core component of new energy vehicles, batteries have high requirements for reliability in use.

[0005] However, how to improve the reliability of batteries during use has always been a difficult problem in the industry.

[0006] Summary of the Invention

[0007] The purpose of this application is to improve the working reliability of the battery.

[0008] According to a first aspect of the present application, a battery cell is provided, comprising:

[0009] a housing comprising a first wall;

[0010] an electrode assembly disposed in the housing, the electrode assembly comprising an electrode body and a first electrode tab, the first electrode tab being led out from the electrode body; and

[0011] The first current collecting member is used to electrically connect the first electrode tab and the first wall. The first current collecting member is connected to the inner surface of the first wall through a first weld, and the first weld does not penetrate the outer surface of the first wall.

[0012] In this embodiment, the battery cell welds the first current collector to the first wall from the inside of the first wall, and the first weld does not penetrate the outer surface of the first wall. Compared to welding from the outside of the first wall and melting through the entire thickness, even if cracks appear at the first weld after cooling, the cracks are located on the inside of the first wall, preventing electrolyte leakage through the weld and out of the first wall, thereby improving the reliability of the battery cell during use. In particular, when the first current collector and the first wall are made of different materials, after cooling, the large difference in thermal expansion coefficients between the two materials leads to inconsistent contraction, which is more likely to cause weld cracks. Locating the first weld on the inside of the first wall can better prevent leakage, thereby reducing the requirements for the materials of the first current collector and the first wall.

[0013] In some embodiments, the first weld penetrates the first current collecting member.

[0014] This embodiment facilitates the welding operation and reduces the difficulty of the process. In particular, when the first current collecting member is thin, it can improve the connection strength between the first current collecting member and the first wall, prevent the battery cell from being detached under long-term operation or vibration, improve the reliability of the electrical connection, and ensure the working performance of the battery cell.

[0015] In some embodiments, at least a portion of the first current collector is sandwiched between the first tab and the first wall.

[0016] This embodiment sandwiches the first current collector between the first tab and the first wall, achieving a reliable electrical connection after welding. Even if the first weld seam becomes loose during long-term use or when the battery cell is subjected to vibration, the first current collector maintains reliable contact with the first wall. Furthermore, due to the restraining effect of the first wall, the first current collector maintains reliable contact with the first tab. This structure improves the reliability of the electrical connection between the first tab and the first wall, thereby enhancing the performance and reliability of the battery cell.

[0017] In some embodiments, the first weld is spaced apart from an outer edge of the first current collecting member.

[0018] This embodiment is conducive to increasing the width of the first weld and can design the first weld into different trajectories to improve the welding firmness and reliability; moreover, during laser welding, the welding equipment can emit the laser vertically downward, which can reduce the difficulty of the welding process and facilitate changing the laser position to form the required trajectory; in addition, the first current collecting part can be supported by the first wall during welding, without the need for additional welding tooling.

[0019] In some embodiments, the first weld is formed by welding an outer edge of the first current collecting member to an inner surface of the first wall.

[0020] This embodiment facilitates determining the trajectory of the first weld and directly performs welding along the outer edge of the first current collecting member, which can reduce the difficulty of the process. Moreover, the first current collecting member can be supported by the first wall during welding without the need for additional welding tooling.

[0021] In some embodiments, the first wall has a main body and a connecting portion, the connecting portion protrudes toward the first current collecting member relative to the main body along the thickness direction of the first wall, and the connecting portion contacts the first current collecting member, and the first weld is formed by welding the first current collecting member and the connecting portion.

[0022] In this embodiment, when the first wall and the first current collecting member are spaced apart, a connecting portion can be provided on the first wall to abut against the first current collecting member for welding, which is conducive to designing the first current collecting member into a structure with uniform thickness and reducing the difficulty of manufacturing the first current collecting member.

[0023] In some embodiments, the first wall has a recessed portion, the inner side wall of the connecting portion and the inner surface of the main body portion define the recessed portion, the first current collecting piece is at least partially located in the recessed portion, and the first weld is formed by welding the outer edge of the first current collecting piece and the inner side wall of the connecting portion.

[0024] This embodiment arranges the first current collecting member in the recessed portion, which does not require additional space in the height direction of the battery cell. This can reduce the height of the battery cell to improve energy density, and can also reduce the area of ​​the first current collecting member to save materials.

[0025] In some embodiments, along the thickness direction of the first wall, a surface of the first current collecting member facing the electrode assembly is closer to the electrode assembly than an inner surface of the bottom wall of the connecting portion.

[0026] In this embodiment, during the assembly of the battery cell, when the first electrode tab is welded to the first current collector, even if the outer edge of the first electrode tab exceeds the outer edge of the first current collector, the first current collector can still make good contact with the kneaded flat surface of the first electrode tab, thereby improving the reliability of the electrical connection between the first current collector and the first electrode tab, thereby improving the performance and reliability of the battery cell.

[0027] In some embodiments, the first weld is formed by welding the first current collecting member to the bottom wall of the connecting portion.

[0028] This embodiment can provide support through the bottom wall of the connecting portion during welding, making the welding process more stable and reliable, without the need for additional supporting tooling, and also reducing the positioning requirements for the first current collecting member.

[0029] In some embodiments, the first current collecting member includes a first portion and a second portion connected to each other, the first portion is used for welding to the first wall, and the second portion is used for welding to the first tab.

[0030] In this embodiment, different parts of the first current collecting member are welded to the first wall and the first electrode tab respectively, which facilitates the welding operation and the welds of the two parts do not affect each other, thereby ensuring welding reliability.

[0031] In some embodiments, the thickness of the first portion is less than the thickness of the second portion.

[0032] In this embodiment, the thickness of the first part is smaller than that of the second part. When the first part is penetrated and welded to the first wall, it is easier to penetrate the first part, which can reduce the power required for laser welding. The material of the first current collecting part integrated into the first wall can be reduced during welding, which can reduce the risk of cracks at the first weld.

[0033] In some embodiments, the thickness of the first portion is smaller than the thickness of the welding region between the first wall and the first portion.

[0034] In this embodiment, the thickness of the first part is smaller than the thickness of the welding area between the first wall and the first part. When the first part is penetrated and welded to the first wall, it is easier to penetrate the first part, which can reduce the power required for laser welding. The thicker first wall can prevent the first weld from penetrating the outer surface of the first wall during welding, which can reduce the requirements for welding accuracy and reduce the risk of leakage in the battery cell.

[0035] In some embodiments, the first current collecting member and the first wall are made of different materials.

[0036] If the first current collector and the first wall are made of different materials, after the welding process cools down, the two materials will shrink to different degrees due to the large difference in thermal expansion coefficients, which makes welding cracks more likely to occur. Even if cracks appear at the first weld, the cracks are located on the inside of the first wall, which can still prevent the electrolyte from leaking out of the first wall through the weld, thereby improving the reliability of the battery cell during use and reducing the requirements for the material selection of the first current collector and the first wall.

[0037] In some embodiments, the first current collecting member is a negative electrode current collecting member, the first current collecting member comprises copper, and the first wall comprises steel.

[0038] In this embodiment, when welding to form the first weld seam, copper atoms generated by the melting of the first current collector will enter the first wall. Due to the large difference in thermal expansion coefficients between copper and steel, after cooling, although the two materials shrink to different degrees and welding cracks are likely to occur, the welding cracks are also located inside the first wall, which can still prevent the electrolyte from leaking out of the first wall through the weld seam, thereby improving the reliability of the battery cell during use.

[0039] In some embodiments, the first wall has a second opening, and the second opening is used for allowing a laser for welding the first current collector and the first electrode tab to pass through.

[0040] During assembly, the first current collector is pre-welded to the first wall, and then the electrode assembly is placed into the housing. At this time, the first tab and the first current collector have not yet been welded. By setting the second opening on the first wall, the first current collector and the first tab can be conveniently welded.

[0041] In some embodiments, the second opening and the first wall have the same central axis, and the first weld is located outside the second opening.

[0042] This embodiment sets a second opening in the central area of ​​the first wall, which can reduce the weakening of the strength of the first wall and facilitate the flexible design of the welding trajectory when welding the first current collecting piece and the first pole ear, and can realize a welding trajectory that is closed all around, which is beneficial to improving welding reliability and current flow capacity; moreover, the first weld is located on the outside of the second opening, and when the first current collecting piece and the first wall are pre-welded, the first wall and the first current collecting piece can be welded at a position close to the outer edge, making the connection more reliable. Since the first current collecting piece is thinner, the edge area of ​​the first current collecting piece can be prevented from being deformed when subjected to external force, and even the first current collecting piece can be prevented from being separated from the first wall.

[0043] In some embodiments, a second weld is formed between the first current collecting member and the first electrode tab, and the second weld does not exceed a projection area of ​​the second opening on the first current collecting member.

[0044] This embodiment can facilitate laser welding at an angle perpendicular to the first current collecting member during the welding process, without adjusting the laser emission angle, thereby reducing process difficulty and improving welding reliability and firmness.

[0045] In some embodiments, the battery cell further includes a closing member covering the second opening.

[0046] In this embodiment, after the first electrode tab and the first current collecting member are welded through the second opening, the second opening is sealed by a sealing member to prevent liquid leakage.

[0047] In some embodiments, the sealing member is provided with a notch, and the notch is configured to be broken when the internal pressure of the battery cell exceeds a preset threshold value to release the pressure.

[0048] The sealing member in this embodiment acts as a pressure relief component. When the internal pressure of the battery cell exceeds a preset threshold, gas flows through the first through-hole toward the sealing member, passes through the second through-hole in the center of the first current collector, and acts on the inner surface of the sealing member. The thin notch is damaged, releasing pressure and improving the safety of the battery cell. Furthermore, the opening pressure of the pressure relief component can be flexibly set and precisely controlled by varying the extension path and depth of the notch.

[0049] In some embodiments, the closing component is welded to the first wall to form a third weld, and the third weld is configured to be broken when the internal pressure of the battery cell exceeds a preset threshold to relieve pressure.

[0050] The closing component in this embodiment serves as a pressure relief component. When the internal pressure of the battery cell exceeds a preset threshold, the gas flows along the first through hole toward the closing component, passes through the second through hole in the center of the first current collecting member, and acts on the inner surface of the closing component, causing the closing component to arch outward, thereby increasing the force at the third weld seam, destroying the third weld seam to achieve pressure relief, and improving the safety of the battery cell operation.

[0051] Moreover, the closing component is connected to the first wall by welding, the weak part is the third weld, the minimum thickness of the closing component is the thickness of the plate itself, the thickness consistency of different areas is high, it is easy to ensure the opening pressure of the closing component, and there is no need to form notches by local punching, which can reduce the problems of stress concentration and grain crushing. The steel can obtain higher strength than the base material at the weld position and is not easy to be damaged. It will only be damaged and pressure relieved under the action of high pressure of gas.

[0052] In some embodiments, the third weld is spaced apart from an outer edge of the closure member.

[0053] This embodiment is conducive to increasing the width of the third weld to achieve the opening pressure required for the closed component and improve the welding firmness and reliability; moreover, during laser welding, the welding equipment can emit laser vertically downward, which can reduce the difficulty of the welding process.

[0054] In some embodiments, a region of the first wall adjacent to the second opening is entirely recessed inward to form a first groove, and the closing component is at least partially located in the first groove.

[0055] This embodiment reduces the protruding height of the closing component relative to the first wall by providing the first groove, thereby reducing the risk of deformation or damage of the closing component due to external forces such as collisions, thereby improving the pressure relief reliability of the battery cell; moreover, when the outer shell is inverted with the closing component facing downward to pour electrolyte, the outer shell can also be placed more stably.

[0056] In some embodiments, the third weld is formed by welding an outer edge of the closing component to the bottom wall of the first groove.

[0057] This embodiment facilitates determining the trajectory of the third weld and directly performs welding along the outer edge of the closing component, which can reduce the difficulty of the process; moreover, a portion of the third weld is accumulated in the corner area formed between the outer edge of the closing component and the bottom wall of the first groove, which can improve the welding reliability and strength.

[0058] In some embodiments, a second groove is provided on the bottom wall of the first groove, the closing component is provided in the second groove, and the third weld is formed by welding the outer edge of the closing component to the side wall of the second groove.

[0059] In this embodiment, the sealing component is arranged in the second groove, which allows the sealing component to be further retracted inward relative to the outer surface of the first wall, preventing the sealing component from being deformed or damaged by external forces such as collisions, thereby improving the pressure relief reliability of the battery cell.

[0060] In some embodiments, a thinned portion is provided on the outer periphery of the closing component, and the thinned portion overlaps the first wall.

[0061] This embodiment features a thinned portion around the perimeter of the sealing member, making it easier to penetrate the thinned portion during welding, improving weld strength and reliability. Furthermore, the sealing member is locally thinned at the edges and thicker in the center, enhancing overall strength and preventing deformation caused by gassing within the battery cells.

[0062] In some embodiments, a third groove is provided on the inner surface of the closing component in a region near the outer edge, so that a thinned portion is formed on the outer edge of the closing component.

[0063] This embodiment facilitates the cooperation between the central thickened portion of the closing component and the second opening, and can play a positioning role. No additional positioning is required when welding the closing component, and the closing component will not be misplaced during the welding process, thereby improving welding reliability.

[0064] In some embodiments, the closing component is provided with a reinforcing rib, which protrudes toward the first current collecting member.

[0065] This embodiment provides reinforcing ribs on the sealing member to enhance its overall strength and prevent deformation from external forces or gas generation within the battery cells. Furthermore, the ribs protrude toward the first current collector, preventing deformation or damage to the sealing member from external forces such as collisions.

[0066] In some embodiments, the electrode assembly further includes a second electrode tab, and the second electrode tab and the first electrode tab are respectively led out from two ends of the electrode body.

[0067] In this embodiment, the second tab and the first tab are respectively led out from the two ends of the electrode body, and the second opening on the first wall can be used to weld the closed component, which has a simple structure; and can increase the connection area between the tab on each side and the current collector, thereby improving the flow capacity and optimizing the performance of the battery cell.

[0068] In some embodiments, the battery cell further includes an electrode terminal and a second current collector, the housing further includes a side wall and a second wall opposite to the first wall, the electrode terminal is insulated and arranged on the second wall, and the electrode terminal is electrically connected to the second tab through the second current collector.

[0069] In this embodiment, the electrode terminal is provided on the second wall of the housing. When the second electrode tab and the first electrode tab are led out from both ends of the electrode body, they can be conveniently electrically connected to the electrode terminal and the end cover respectively.

[0070] In some embodiments, the housing includes a container and an end cover, the end cover is fixedly connected to the first opening of the container, and the first wall serves as the end cover.

[0071] When assembling the battery cell, this embodiment can pre-weld the first current collector and the end cover to form an end cover assembly, which is different from the traditional method of welding the end cover to the current collector from the outside after installing the end cover. Moreover, after the welding cools down, even if cracks appear at the first weld, the welding cracks are located on the inside of the end cover, which can still prevent the electrolyte from leaking out of the end cover through the weld, thereby improving the reliability of the battery cell during use. In particular, for the case where the first current collector and the end cover are made of different materials, after cooling, due to the large difference in the thermal expansion coefficients of the two materials, the inconsistent shrinkage of the two materials makes it more likely to produce welding cracks. The first weld is located on the inside of the end cover to better solve the leakage problem, thereby reducing the requirements for the materials of the first current collector and the end cover. Moreover, by pre-welding the first current collector and the end cover, there is no need to perform welding operations inside the cavity of the shell, and the welding difficulty is low and easy to operate.

[0072] According to a second aspect of the present application, a battery is provided, comprising the battery cell of the above embodiment.

[0073] According to a third aspect of the present application, an electrical device is provided, comprising the battery cell and / or battery of the above embodiment, for providing electrical energy to the electrical device.

[0074] According to a fourth aspect of the present application, a method for manufacturing a battery cell is provided, comprising:

[0075] Providing an assembly step: providing a container, an end cap assembly, and an electrode assembly, wherein the electrode assembly includes an electrode body and a first electrode tab, the first electrode tab extending from the electrode body, and the end cap assembly includes an end cap and a first current collector, wherein the first current collector is connected to an inner surface of the end cap by a first weld, and the first weld does not penetrate an outer surface of the end cap;

[0076] Electrode placement step: placing the electrode assembly into the container through the first opening of the container;

[0077] End cap sealing step: closing the end cap assembly on the first opening;

[0078] Electrical connection step: electrically connecting the first current collecting member to the first electrode tab.

[0079] In this embodiment, the battery cell welds the first current collector to the end cap from the inside, and the first weld does not penetrate the outer surface of the end cap. Compared to welding from the outside of the end cap and melting throughout its entire thickness, even if cracks appear at the first weld after cooling, the cracks are located on the inside of the end cap, preventing electrolyte leakage through the weld and out of the end cap, thereby improving the reliability of the battery cell during use. In particular, when the first current collector and the end cap are made of different materials, the significant difference in thermal expansion coefficients after cooling makes the two materials contract more likely to cause weld cracks. Locating the first weld on the inside of the end cap can better prevent leakage, thereby reducing the material requirements for the first current collector and the end cap.

[0080] In some embodiments, the end cap has a second opening, and the step of electrically connecting includes:

[0081] The laser welds the first current collecting member and the first electrode tab through the second opening.

[0082] The second opening in this embodiment forms a channel for laser welding the first current collector and the first pole tab. Since the end cover and the first current collector are pre-welded to form an end cover assembly, when assembling the battery cell, the end cover assembly is integrally covered on the first opening. At this time, the first current collector and the first pole tab have not yet been welded. By providing a second opening on the end cover, the first current collector and the first pole tab can be conveniently welded after the end cover assembly is installed.

[0083] In some embodiments, the end cap assembly further comprises a sealing member, and after the electrical connection step, the manufacturing method further comprises:

[0084] The closing component is made to cover the second opening, and the closing component and the end cover are welded to form a third weld.

[0085] The second opening of this embodiment can be used for welding the first electrode tab and the first current collecting member. After the welding is completed, the second opening is closed by welding a closing component to achieve the closure of the housing.

[0086] In some embodiments, after the end cap sealing step, the manufacturing method further comprises:

[0087] Connect the outer edge of the end cap to the receiving member at the first opening.

[0088] This embodiment can reliably seal the container with the end cover, preventing the electrolyte from leaking from the connection between the end cover and the container. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] 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.

[0090] FIG1 is a schematic structural diagram of some embodiments of the present application for installing a battery on a vehicle.

[0091] FIG2 is an exploded view of the first embodiment of the battery of the present application.

[0092] FIG3 is a cross-sectional view of some embodiments of a battery cell of the present application.

[0093] FIG4 is a schematic structural diagram of the side where the end cover is located in the battery cell of the present application.

[0094] FIG5 is a schematic structural diagram of the side where the electrode terminals are located in the battery cell of the present application.

[0095] FIG6 is a schematic structural diagram of some embodiments of the end cover.

[0096] FIG7 is a structural diagram of a first embodiment of welding the first current collecting member to the end cover.

[0097] FIG8 is a structural diagram of a second embodiment of welding the first current collecting member to the end cover.

[0098] FIG9 is a structural diagram of a third embodiment of welding the first current collecting member to the end cover.

[0099] FIG10 is a schematic structural diagram of a first embodiment of welding a sealing component to an end cover.

[0100] FIG11 is a schematic structural diagram of a second embodiment of welding a sealing component to an end cover.

[0101] FIG12 is a schematic structural diagram of a third embodiment of welding a sealing component to an end cover.

[0102] FIG. 13 is a schematic structural diagram of some embodiments of a sealing component.

[0103] FIG. 14 is a schematic structural diagram of other embodiments of the sealing component.

[0104] FIG15 is a schematic flow chart of some embodiments of the battery cell manufacturing method of the present application.

[0105] In the drawings, the drawings are not drawn to scale.

[0106] Marking instructions: 100, battery cell; 1, shell; 1', container; 11, first opening; 12, side wall; 13, first wall; 14, second wall; 2, end cover; 2', end cover assembly; 20, main body; 21, connecting portion; 22, second opening; 23, first groove; 24, second groove; 25, recessed portion; 3, electrode assembly; 31, electrode body; 311, first through hole; 32, first tab; 33, second tab; 4, first current collector; 41, first weld; 42, second weld; 43, second through hole; 44, first part; 45, second part; 5, closing component; 51, third weld; 52, third groove; 53, thinning portion; 54, reinforcing rib; 6, second current collector; 7, insulating plate; 8, electrode terminal; 81, fourth groove; 82, injection hole; 83, Cover plate; 9. First insulating member; 10. Second insulating member; 200. Battery; 201. Box assembly; 201A. Box; 201B. First cover; 201C. Second cover; 300. Vehicle; 301. Axle; 302. Wheel; 303. Motor; 304. Controller. DETAILED DESCRIPTION

[0107] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0108] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0109] This application uses descriptions of directions or positional relationships such as "up", "down", "top", "bottom", "front", "back", "inside" and "outside" to facilitate the description of this application, and does not indicate or imply that the device referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, it should not be understood as limiting the scope of protection of this application.

[0110] Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Perpendicular" does not strictly refer to perpendicularity, but rather to the tolerances allowed. "Parallel" does not strictly refer to parallelism, but rather to the tolerances allowed. The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application.

[0111] It should also be noted that, in the description of this application, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0112] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least some embodiments of the present 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. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0113] Current battery cells usually include a shell and an electrode assembly housed in the shell, and the shell is filled with an electrolyte. The electrode assembly is mainly formed by stacking or winding a first electrode sheet and a second electrode sheet with opposite polarities, and an insulating member, such as a diaphragm, is usually provided between the first electrode sheet and the second electrode sheet. The portions of the first electrode sheet and the second electrode sheet coated with active material constitute the main body of the electrode assembly, and the portions of the first electrode sheet and the second electrode sheet not coated with active material each constitute the first electrode tab and the second electrode tab. In a battery cell, the first electrode sheet can be a positive electrode sheet, including a positive electrode current collector and a positive electrode active material layer provided on both sides of the positive electrode current collector. The positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate made of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The positive electrode active material layer may include at least one of the following materials: lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. The second electrode sheet may be a negative electrode sheet, including a negative electrode current collector and a negative electrode active material layer provided on both sides of the negative electrode current collector. The negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative electrode active material layer can adopt the negative electrode active material for batteries known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material and lithium titanate, etc. Optionally, the first pole piece can also be a negative pole piece, and the corresponding second pole piece is a positive pole piece. The first pole piece and the second pole piece can be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery cell, the positive electrode active material and the negative electrode active material react with the electrolyte, and the pole pieces connect the electrode terminals to form a current loop.

[0114] Among them, cylindrical battery cells can leak during operation, significantly impacting their reliability. Research has found that the primary cause of leakage is that, in order to allow for same-side electrode terminal extraction, the battery cell uses the outer casing, typically made of steel, as the electrode lead-out portion. The electrode assembly is formed by winding positive and negative electrode sheets and a separator. The negative electrode sheet is made of copper foil. When the negative electrode tab is extracted from the outer casing, the copper negative current collector must be welded to the steel outer casing. When welding from the outside of the outer casing, copper atoms are incorporated into the weld. Due to the mismatch in thermal expansion coefficients between copper and steel, the two materials shrink at different rates after the weld cools, leading to a higher risk of weld cracks.

[0115] To solve the above problems, one solution is to use a steel-copper composite current collecting plate, welding the steel part of the current collecting plate to the outer shell, and the copper part to the negative electrode tab. Due to the inconsistent thermal expansion coefficients and thermal conductivity coefficients of the copper and steel in the current collecting plate, and the current collecting plate is relatively thin and lacks its own rigidity, distortion caused by asynchronous thermal deformation is prone to occur during the manufacture of the current collecting plate. After the current collecting plate is welded, the secondary deformation will be aggravated, making the entire current collecting plate wavy and affecting subsequent assembly. Another solution is to use internal welding, that is, welding the current collecting plate to the side wall of the outer shell, but internal welding requires very high equipment precision, which is not conducive to mass production.

[0116] Based on the shortcomings of the above-mentioned solutions, the present application proposes a battery cell, comprising: a shell, including a first wall; an electrode assembly, arranged in the shell, the electrode assembly including an electrode body and a first electrode tab, the first electrode tab being led out from the electrode body; and a first current collector, used to electrically connect the first electrode tab and the first wall, the first current collector being connected to the inner surface of the first wall by a first weld, and the first weld does not penetrate to the outer surface of the first wall.

[0117] In this embodiment, the battery cell welds the first current collector to the first wall from the inside of the first wall, and the first weld does not penetrate the first wall. Compared to welding from the outside of the first wall and melting through the entire thickness, even if cracks appear at the first weld after cooling, the cracks are located on the inside of the first wall, preventing electrolyte leakage through the weld and out of the first wall, thereby improving the reliability of the battery cell during use. In particular, when the first current collector and the first wall are made of different materials, the significant difference in thermal expansion coefficients after cooling makes the two materials contract more likely to cause weld cracks. Locating the first weld on the inside of the first wall can better prevent leakage, thereby reducing the requirements for the materials of the first current collector and the first wall.

[0118] The battery cells of the embodiments of the present application are applicable to batteries and electrical devices using such battery cells, and the batteries are also applicable to electrical devices.

[0119] The battery of the embodiment of the present application can be used in an electrical device, which can be a battery car, an electric car, a ship, or a spacecraft, for example, a spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft.

[0120] As shown in Figure 1 , the power-consuming device can be a vehicle 300, such as a new energy vehicle, which can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle; or the power-consuming device can be a drone or a ship. Specifically, vehicle 300 may include an axle 301, wheels 302 connected to axle 301, a motor 303, a controller 304, and a battery 200. Motor 303 is used to drive axle 301, and controller 304 is used to control the operation of motor 303. Battery 200 can be located at the bottom, front, or rear of vehicle 300 to provide power to motor 303 and other components of the vehicle.

[0121] As shown in Figure 2, the battery 200 includes a housing assembly 201 and battery cells 100. In the battery 200, there can be one or more battery cells 100. If there are multiple battery cells 100, the multiple battery cells 100 can be connected in series, in parallel, or in a hybrid connection. Hybrid connection means that the multiple battery cells 100 are connected in both series and parallel. Multiple battery cells 100 can be connected in series, in parallel, or in a hybrid connection to form a battery module, and the multiple battery modules can then be connected in series, in parallel, or in a hybrid connection to form a whole and accommodated in the housing assembly 201. Alternatively, all battery cells 100 can be directly connected in series, in parallel, or in a hybrid connection, and then the whole formed by all battery cells 100 is accommodated in the housing assembly 201.

[0122] Among them, the box assembly 201 can be a part of the battery pack, and the box assembly 201 can be detachably installed on the electrical device; or, the box assembly 201 can also be a space formed by a structural member in the electrical device for accommodating the battery cell 100. For example, when the battery cell 100 is used in the vehicle 300, the box assembly 201 is a space formed by the vehicle frame for accommodating the battery cell 100.

[0123] The housing assembly 201 is hollow and is used to accommodate one or more battery cells 100. Depending on the shape, quantity, and combination of the battery cells 100 to be accommodated, as well as other requirements, the housing assembly 201 can have different shapes and sizes. For example, the housing assembly 201 may include: a housing 201A, a first cover 201B, and a second cover 201C. The housing 201A has openings at both ends, and the first and second covers 201B and 201C are used to seal the openings at both ends of the housing 201A. In Figure 2, the housing 201A has a rectangular cylindrical structure based on the arrangement of the multiple battery cells 100. To facilitate maintenance of the batteries 200, the housing assembly 201 can be removably mounted to the electrical device.

[0124] The battery cell 100 may be a secondary battery. A secondary battery refers to a battery cell 100 that can be continuously used by activating active materials by charging after the battery cell 100 is discharged.

[0125] The battery cell 100 can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel metal hydride battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0126] As an example, the battery cell 100 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, and a polygonal battery such as a hexagonal battery. There is no special limitation in this application.

[0127] The following description uses cylindrical battery cells 100 as an example, but is also applicable to battery cells of other shapes. Multiple battery cells 100 can be arranged in a plurality of planes xoy perpendicular to a first direction z. The multiple battery cells 100 can be arranged in a rectangular array along a second direction x and a third direction y, with the second direction x being perpendicular to the third direction y.

[0128] Figure 3 is a cross-sectional view of some embodiments of a battery cell according to the present application. In some embodiments, the battery cell 100 includes: a housing 1 including a first wall 13; an electrode assembly 3 disposed within the housing 1, the electrode assembly 3 including an electrode body 31 and a first electrode tab 32 extending from the electrode body 31; and a first current collector 4 for electrically connecting the first electrode tab 32 to the first wall 13. The first current collector 4 is connected to the inner surface of the first wall 13 via a first weld 41, and the first weld 41 does not penetrate the outer surface of the first wall 13.

[0129] The outer shell 1 has a thin-walled hollow structure for accommodating the electrode assembly 3 and the electrolyte. The outer shell 1 may be a steel shell, an aluminum shell, a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film. The outer shell 1 may include a sidewall 12, a first wall 13, and a second wall 14. The first wall 13 and the second wall 14 are respectively connected to the ends of the sidewall 12. The first wall 13 may be the bottom wall of the outer shell 1. From the perspective of component composition, the outer shell 1 includes a container 1' and an end cap 2. The end cap 2 is fixedly connected to the first opening 11 of the container 1'. The first wall 13 is the end cap 2, and the sidewall 12 is the side wall of the container 1'. The first wall 13 is the end cap 2. If the end of the container 1' opposite the first opening 11 adopts a closed structure, the second wall 14 may be formed integrally with the sidewall 12. If the end of the container 1' opposite the first opening 11 is provided with an opening, it can be closed by the end cap. The second wall 14 also serves as the end cap.

[0130] The electrode assembly 3 is formed by winding a first electrode sheet and a second electrode sheet of opposite polarity around a winding axis K. The winding axis K is aligned with the first direction z. A separator, such as a diaphragm, is typically provided between the first and second electrode sheets. For cylindrical battery cells 100, the wound electrode assembly 3 can be cylindrical; for rectangular battery cells 100, the wound electrode assembly 3 can be flat.

[0131] The portions of the first and second pole pieces coated with active material constitute the electrode body 31. A first through-hole 311 is provided in the center of the electrode body 31 for accommodating electrolyte or serving as an exhaust channel for pressure relief. The portions of the first and second pole pieces not coated with active material each constitute a first pole tab 32 and a second pole tab 33. One of the first and second pole tabs 32, 33 is a negative pole tab, and the other is a positive pole tab. The first and second pole tabs 32, 33 are both extended from the electrode body 31. For example, the first and second pole tabs 32, 33 can be extended from the same end of the electrode body 31, or can be extended from both ends of the electrode body 31. The first pole tab 32 is electrically connected to the end cap 2 via the first current collector 4, and the second pole tab 33 is electrically connected to the electrode terminal 8 via the second current collector 6.

[0132] The first current collector 4 is electrically connected to the first wall 13 by welding, for example, laser welding. The first current collector 4 is connected to the inner surface of the first wall 13 by a first weld 41. Specifically, the first current collector 4 can be a thin plate with uniform thickness, or it can have locally recessed, convex, or curved features. For cylindrical battery cells 100, both the first current collector 4 and the second current collector 6 can be disc-shaped.

[0133] During welding, the welding equipment is operated from the side of the first current collecting part 4 away from the first wall 13. In order to facilitate welding, the first wall 13 can be inverted on the working platform, and the first current collecting part 4 can be positioned at a suitable position inside the first wall 13. The first current collecting part 4 can be supported by the first wall 13 or other tooling.

[0134] Figure 4 is a schematic structural diagram of the battery cell near the first wall side. The first weld 41 does not penetrate the outer surface of the first wall 13. In other words, there is a preset distance between the first weld 41 and the outer surface of the first wall 13, or the first weld 41 does not reach or extend to the outer surface of the first wall 13, or the first weld 41 is only located on the inner side of the outer surface of the first wall 13.

[0135] In this embodiment of the battery cell 100, the first current collector 4 is welded to the first wall 13 from the inside of the first wall 13, and the first weld 41 does not penetrate the outer surface of the first wall 13. Compared to welding from the outside of the first wall 13 and melting throughout the entire thickness, even if cracks appear at the first weld 41 after the weld cools, the cracks are located on the inside of the first wall 13, preventing electrolyte leakage through the weld and out of the first wall 13, thereby improving the reliability of the battery cell 100 during use. In particular, when the first current collector 4 and the first wall 13 are made of different materials, after cooling, the different thermal expansion coefficients of the two materials make the different degrees of contraction during cooling more likely to cause weld cracks. Locating the first weld 41 on the inside of the first wall 13 can better prevent leakage, thereby reducing the material requirements for the first current collector 4 and the first wall 13.

[0136] Secondly, in conventional battery cells, welding is performed from the outside of the end cap after the electrode assembly 3 is installed. This increases the thickness of the first current collector 4 to prevent penetration of the first current collector 4, which not only wastes material but also causes more of the first current collector 4 material to be integrated into the first wall 13 during welding, increasing the risk of weld cracks. In contrast, the present invention welds from the inside of the first wall 13, allowing penetration of the first current collector 4. While maintaining current flow capacity, the thickness of the first current collector 4 can be reduced, thereby reducing the amount of first current collector 4 material integrated into the first wall 13, lowering the risk of weld cracks, and reducing the space occupied by the battery cell 100 in the thickness direction, thereby saving material.

[0137] Again, before assembling the battery cell 100, in order to make the first weld 41 located on the inner side of the first wall 13, it is necessary to first weld the first current collector 4 to the first wall 13. Compared with the traditional method of welding from the outside after installing the electrode assembly 3, it can prevent the high temperature of welding from burning the isolation part, which is beneficial to ensure the insulation performance between the positive electrode plate and the negative electrode plate, so as to avoid short circuit of the battery cell 100 during operation, thereby improving the reliability of the battery cell 100 during use.

[0138] Finally, compared with the internal welding method between the first current collecting part 4 and the side wall of the outer shell 1, the battery cell 100 of the present application does not need to be provided with a folded edge on the outer edge of the first current collecting part 4, and can reduce the space occupied by the battery cell 100 in the height direction, thereby improving the energy density of the battery cell 100.

[0139] In some embodiments, the first current collecting member 4 and the first wall 13 are made of different materials.

[0140] For example, the main body of the first current collector 4 can be made of a variety of materials, such as copper or aluminum. If the first current collector 4 is a positive electrode current collector, the main body is typically aluminum; if the first current collector 4 is a negative electrode current collector, the main body is typically copper. The main body of the first wall 13 is typically made of aluminum, an aluminum alloy, or steel. To achieve rust resistance, the outer surfaces of the first current collector 4 and the first wall 13 can be nickel-plated.

[0141] It should be noted that the different materials of the first current collecting member 4 and the first wall 13 refer to differences in the primary components of the first current collecting member 4 and the primary components of the first wall 13. For example, if the first current collecting member 4 and the first wall 13 are both made of a single material, then the materials of the first current collecting member 4 and the first wall 13 are composed of different metallic elements. If the first current collecting member 4 and the first wall 13 are made of an alloy or a mixed material, then the primary components of the first current collecting member 4 and the first wall 13 are different, not just a difference in the content of the components.

[0142] If the first current collector 4 and the first wall 13 are made of different materials, after the welding process cools down, the two materials may shrink to different degrees due to a large difference in thermal expansion coefficients, making welding cracks more likely to occur. Even if cracks appear at the first weld 41, the cracks are located on the inner side of the first wall 13, which can still prevent the electrolyte from leaking out of the first wall 13 through the weld, thereby improving the reliability of the battery cell 100 during use and reducing the requirements for the material selection of the first current collector 4 and the first wall 13.

[0143] Optionally, the first current collecting member 4 and the first wall 13 are made of the same material, that is, the main component of the first current collecting member 4 is the same as the main component of the first wall 13. For example, if the first current collecting member 4 and the first wall 13 are both made of a single material, they are both composed of the same metal element; if the first current collecting member 4 and the first wall 13 are made of an alloy or a mixed material, the main component of the first current collecting member 4 and the first wall 13 is the same; if the first current collecting member 4 and the first wall 13 differ only in the content of the component, they are also made of the same material, for example, low carbon steel, medium carbon steel, and high carbon steel are all the same material.

[0144] In some embodiments, the first current collecting member 4 is a negative electrode current collecting member, the first current collecting member 4 comprises copper, and the first wall 13 comprises steel.

[0145] To achieve rust prevention, the outer surfaces of the first current collecting member 4 and the first wall 13 may be nickel plated. Since the first current collecting member 4 and the first wall 13 have different main components, the first current collecting member 4 and the first wall 13 are made of different materials.

[0146] Optionally, the first current collecting member 4 may also be a positive electrode current collecting member.

[0147] In this embodiment, when the first weld 41 is formed by welding, the copper atoms generated by the melting of the first current collector 4 will enter the first wall 13. Due to the large difference in thermal expansion coefficients between copper and steel, after cooling, although the two materials shrink to different degrees and welding cracks are likely to occur, the welding cracks are also located inside the first wall 13, which can still prevent the electrolyte from leaking out of the first wall 13 through the weld, thereby improving the reliability of the battery cell 100 during use.

[0148] In some embodiments, the first weld 41 penetrates the first current collecting member 4 .

[0149] The first welding seam 41 penetrates the first current collecting member 4 and extends toward the first wall 13 to weld the first current collecting member 4 and the first wall 13 together.

[0150] This embodiment facilitates the welding operation and reduces the difficulty of the process. In particular, when the first current collecting member 4 is thin, the connection strength between the first current collecting member 4 and the first wall 13 can be improved, thereby preventing the battery cell 100 from being disconnected when working for a long time or being vibrated, thereby improving the reliability of the electrical connection and ensuring the working performance of the battery cell 100.

[0151] In some embodiments, as shown in FIG. 4 , at least a portion of the first current collecting member 4 is sandwiched between the first electrode tab 32 and the first wall 13 .

[0152] The first current collecting member 4 includes a first portion 44 and a second portion 45 connected to each other. For example, the first current collecting member 4 is disc-shaped. Although its thickness is uniform, it can still be functionally divided into a first portion 44 and a second portion 45. The first portion 44 is located radially outward of the second portion 45 and is annular. The first portion 44 is used for welding to the first wall 13, and the second portion 45 is used for welding to the first electrode tab 32. Specifically, the first portion 44 is located between the first electrode tab 32 and the first wall 13, and the two side surfaces of the first portion 44 are in contact with the first electrode tab 32 and the first wall 13, respectively.

[0153] Optionally, the first current collecting member 4 is only welded to the first wall 13 and is not limited by the first wall 13 .

[0154] This embodiment sandwiches the first current collector 4 between the first tab 32 and the first wall 13, achieving a reliable electrical connection after welding. Even if the first weld 41 becomes detached during long-term use or when the battery cell 100 is subjected to vibration, the first current collector 4 maintains reliable contact with the first wall 13. Furthermore, due to the restraining effect of the first wall 13, the first current collector 4 maintains reliable contact with the first tab 32. This structure improves the reliability of the electrical connection between the first tab 32 and the first wall 13, thereby enhancing the performance and reliability of the battery cell 100.

[0155] In some embodiments, as shown in FIG. 6 and FIG. 7 , the first weld 41 is spaced apart from the outer edge of the first current collecting member 4 .

[0156] During welding, the laser first acts on the surface of the first current collecting member 4 away from the first wall 13. The extension trajectory of the first weld 41 can be continuous or discontinuous annular, with only one annular weld provided, or at least two annular welds spaced apart in the radial direction of the first current collecting member 4. Alternatively, the first weld 41 can be provided in other straight or curved extension forms to improve the connection reliability between the first wall 13 and the first current collecting member 4.

[0157] Specifically, as shown in Figure 7, the first wall 13 has a main body portion 20 and a connecting portion 21. The connecting portion 21 protrudes toward the first current collecting member 4 as a whole relative to the main body portion 20 along the thickness direction of the first wall 13 to form a U-shape, and the connecting portion 21 is in contact with the first current collecting member 4. The first weld 41 is formed by welding the first current collecting member 4 to the connecting portion 21. The bottom wall of the connecting portion 21 forms a flat plate to increase the contact area between the connecting portion 21 and the first current collecting member 4. The first portion 44 of the first current collecting member 4 is sandwiched between the connecting portion 21 and the first tab 32. The first weld 41 penetrates the first current collecting member 4 and extends within the bottom wall of the connecting portion 21, and does not exceed the outer surface of the bottom wall of the connecting portion 21. Preferably, the outer edge of the first current collecting member 4 extends to a position close to the outer side wall of the U-shaped connecting portion 21 to increase the width of the area available for welding.

[0158] During welding, the welding equipment is operated from the side of the first current collecting part 4 away from the first wall 13. In order to facilitate welding, the first wall 13 can be inverted on the working platform, and the first current collecting part 4 can be positioned at a suitable position on the first wall 13. The first current collecting part 4 can be supported by the first wall 13.

[0159] This embodiment is conducive to increasing the width of the first weld 41, and the first weld 41 can be designed into different trajectories to improve the welding firmness and reliability; moreover, during laser welding, the welding equipment can emit the laser vertically downward, which can reduce the difficulty of the welding process and facilitate changing the laser position to form the required trajectory; in addition, the first current collecting part 4 can be supported by the first wall 13 during welding, without the need for additional welding tooling.

[0160] In some embodiments, as shown in FIG. 8 , the first weld 41 is formed by welding the outer edge of the first current collecting member 4 to the inner surface of the first wall 13 .

[0161] During welding, the laser is applied to the corner area formed by the outer edge of the first current collecting member 4 and the inner surface of the first wall 13 to achieve a fillet weld. The first weld 41 may fully or partially penetrate the outer edge of the first current collecting member 4. When using laser welding, the welding equipment can emit the laser at an angle to the first current collecting member 4. After welding, the first weld 41 may partially accumulate at the corner area formed by the outer edge of the first current collecting member 4 and the inner surface of the first wall 13 to increase the connection strength. The first weld 41 may extend continuously or intermittently along the outer edge of the first current collecting member 4.

[0162] Specifically, as shown in Figure 8, the first wall 13 includes a main body portion 20 and a connecting portion 21. The connecting portion 21 protrudes relative to the main body portion 20 toward the first current collecting member 4 along the thickness direction of the first wall 13, forming a U-shape. The connecting portion 21 contacts the first current collecting member 4, and a first weld 41 is formed by welding the first current collecting member 4 to the connecting portion 21. The bottom wall of the connecting portion 21 is formed into a flat plate to increase the contact area between the connecting portion 21 and the first current collecting member 4. The first portion 44 of the first current collecting member 4 is sandwiched between the connecting portion 21 and the first tab 32. A portion of the first weld 41 is accumulated in the corner area formed by the side wall of the first current collecting member 4 and the inner surface of the bottom wall of the U-shaped connecting portion 21. Another portion extends inward from the outer wall of the first current collecting member 4 and extends obliquely within the bottom wall of the connecting portion 21, without exceeding the outer surface of the bottom wall of the connecting portion 21.

[0163] This embodiment facilitates determining the trajectory of the first weld 41 and directly performs welding along the outer edge of the first current collecting member 4, which can reduce the difficulty of the process; moreover, the first current collecting member 4 can be supported by the first wall 13 during welding without the need for additional welding tooling.

[0164] In some embodiments, the first wall 13 has a main body portion 20 and a connecting portion 21, the connecting portion 21 protrudes toward the first current collecting part 4 along the thickness direction of the first wall 13, and the connecting portion 21 contacts the first current collecting part 4, and the first weld 41 is formed by welding the first current collecting part 4 and the connecting portion 21.

[0165] The connecting portion 21 may be U-shaped and abut against the first current collecting member 4 , and the bottom wall of the connecting portion 21 may be a flat plate to increase the contact area between the connecting portion 21 and the first current collecting member 4 . The connecting portion 21 may be formed by stamping the first wall 13 .

[0166] For example, the first wall 13 is disc-shaped, and the connecting portion 21 can be located in an area close to the outer edge of the first wall 13 . The connecting portion 21 can form a continuous or discontinuous annular structure, and its structure is determined according to the setting position of the first weld 41 .

[0167] In this embodiment, when the first wall 13 and the first current collecting part 4 are spaced apart, a connecting portion 21 can be provided on the first wall 13 to abut against the first current collecting part 4 for welding, which is conducive to designing the first current collecting part 4 into a structure with uniform thickness and can reduce the manufacturing difficulty of the first current collecting part 4.

[0168] In some embodiments, as shown in Figure 9, the first wall 13 has a recessed portion 25, and the inner side wall of the connecting portion 21 and the inner surface of the main body portion 20 define the recessed portion 25. The first current collecting part 4 is at least partially located in the recessed portion 25, and the first weld 41 is formed by welding between the outer edge of the first current collecting part 4 and the inner side wall of the connecting portion 21.

[0169] The outer edge of the first current collecting member 4 may contact the inner sidewall of the connecting portion 21, or a gap may exist between the outer edge of the first current collecting member 4 and the inner sidewall of the connecting portion 21. The inner sidewall of the connecting portion 21 is adjacent to its bottom wall and close to the central axis of the first wall 13, while the outer sidewall of the connecting portion 21 is adjacent to its bottom wall and close to the outer edge of the first wall 13. The outer sidewall of the connecting portion 21 is located radially outward of the inner edge of the connecting portion 21. The first current collecting member 4 may be located within the recessed portion 25 for part of its thickness or entirely within the recessed portion 25.

[0170] During welding, the laser acts between the outer edge of the first current collecting member 4 and the inner sidewall of the connecting portion 21 to achieve a butt weld. The first weld 41 may fully or partially penetrate the outer edge of the first current collecting member 4 and extend within the inner sidewall of the connecting portion 21, but not through the outer surface of the inner sidewall. The first weld 41 may extend continuously or intermittently along the outer edge of the first current collecting member 4.

[0171] During welding, since the first current collecting member 4 cannot be supported by the first wall 13 , the first current collecting member 4 may be supported by a tool.

[0172] In this embodiment, the first current collecting member 4 is disposed in the recessed portion 25 , which does not require additional space in the height direction of the battery cell 100 . This can reduce the height of the battery cell 100 to improve energy density, and can also reduce the area of ​​the first current collecting member 4 to save materials.

[0173] In some embodiments, along the thickness direction of the first wall 13 , the surface of the first current collecting member 4 facing the electrode assembly 3 is closer to the electrode assembly 3 than the inner surface of the bottom wall of the connecting portion 21 .

[0174] Before the first electrode tab 32 is welded to the first current collecting member 4 , the first electrode tab 32 is flattened to form a welding plane with multiple layers of electrode tabs.

[0175] In this embodiment, during the assembly process of the battery cell 100, when the first pole tab 32 is welded to the first current collector 4, even if the outer edge of the first pole tab 32 exceeds the outer edge of the first current collector 4, the first current collector 4 can still make good contact with the kneaded flat surface of the first pole tab 32, thereby improving the reliability of the electrical connection between the first current collector 4 and the first pole tab 32, thereby improving the performance and reliability of the battery cell 100.

[0176] In some embodiments, the first weld 41 is formed by welding the first current collecting member 4 to the bottom wall of the connecting portion 21 .

[0177] In one structural form, as shown in Figure 7, the first weld 41 is spaced apart from the outer edge of the first current collecting member 4. The bottom wall of the connecting portion 21 forms a flat plate to increase the contact area between the connecting portion 21 and the first current collecting member 4. The first portion 44 of the first current collecting member 4 is sandwiched between the connecting portion 21 and the first pole tab 32, and the first weld 41 penetrates the first current collecting member 4 and extends within the bottom wall of the connecting portion 21, and does not exceed the outer surface of the bottom wall of the connecting portion 21. Preferably, the outer edge of the first current collecting member 4 extends to a position close to the outer side wall of the U-shaped connecting portion 21 to increase the overlap width between the first current collecting member 4 and the connecting portion 21, thereby increasing the width of the area available for welding.

[0178] This structure is conducive to increasing the width of the first weld 41, and the first weld 41 can be designed into different trajectories to improve the welding firmness and reliability; moreover, during laser welding, the welding equipment can emit the laser vertically downward, which can reduce the difficulty of the welding process and facilitate changing the laser position to form the required trajectory; in addition, the first current collecting part 4 can be supported by the first wall 13 during welding, without the need for additional welding tooling.

[0179] In another structural form, as shown in Figure 8, the first weld 41 is formed by welding between the outer edge of the first current collecting part 4 and the bottom wall of the connecting part 21. During welding, the laser acts on the corner area formed by the outer edge of the first current collecting part 4 and the bottom wall of the connecting part 21 to achieve fillet welding, and the first weld 41 can fully or partially penetrate the outer edge of the first current collecting part 4. When laser welding is used, the welding equipment can emit a laser at an angle to the first current collecting part 4. After welding, the first weld 41 can be partially accumulated in the corner area formed by the outer edge of the first current collecting part 4 and the bottom wall of the connecting part 21, and the other part extends inward from the outer side wall of the first current collecting part 4, and extends obliquely inside the bottom wall of the connecting part 21, and does not exceed the outer surface of the bottom wall of the connecting part 21. This welding method can increase the connection strength.

[0180] This structure facilitates determining the trajectory of the first weld 41 and allows welding to be performed directly along the outer edge of the first current collecting member 4, thereby reducing process difficulty. Furthermore, the first current collecting member 4 can be supported by the bottom wall of the connecting portion 21 during welding without the need for additional welding tooling.

[0181] In this embodiment, the bottom wall of the connecting portion 21 can provide support during welding, making the welding process more stable and reliable, eliminating the need for additional supporting fixtures, and reducing the positioning requirements for the first current collecting member 4 .

[0182] In some embodiments, the first current collecting member 4 includes a first portion 44 and a second portion 45 connected to each other. The first portion 44 is used for welding to the first wall 13 , and the second portion 45 is used for welding to the first electrode tab 32 .

[0183] For example, the first current collecting member 4 is a circular disc, with the first portion 44 located radially outward from the second portion 45. The first portion 44 is annular. The first portion 44 and the second portion 45 can be divided by thickness. Alternatively, if the entire first current collecting member 4 has a uniform thickness, the functional divisions can be based on the areas connected to different components. If the outer edge of the first current collecting member 4 is welded to the end cap 2 to form the first weld seam 41, the outer edge of the first current collecting member 4 serves as the first portion 44. The first portion 44 and the second portion 45 are integrally formed.

[0184] In this embodiment, different parts of the first current collecting member 4 are welded to the first wall 13 and the first electrode tab 32 respectively, which facilitates the welding operation and the welds of the two parts do not affect each other, thereby ensuring welding reliability.

[0185] In some embodiments, the thickness of the first portion 44 is less than the thickness of the second portion 45 .

[0186] In this embodiment, the thickness of the first part 44 is smaller than the thickness of the second part 45. When the first part 44 is penetrated and welded to the first wall 13, it is easier to penetrate the first part 44, which can reduce the power required for laser welding. The material of the first current collecting part 4 that is integrated into the first wall 13 can also be reduced during welding, which can reduce the risk of cracks at the first weld 41.

[0187] In some embodiments, the thickness of the first portion 44 is smaller than the thickness of the welding region between the first wall 13 and the first portion 44 .

[0188] In this embodiment, the thickness of the first portion 44 is less than the thickness of the welding area between the first wall 13 and the first portion 44. When the first portion 44 is penetrated and welded to the first wall 13, it is easier to penetrate the first portion 44, which can reduce the power required for laser welding. The thicker first wall 13 can prevent the first weld 41 from penetrating the outer surface of the first wall 13 during welding, which can reduce the requirements for welding accuracy and reduce the risk of leakage of the battery cell 100.

[0189] In some embodiments, the first wall 13 has a second opening 22 , and the second opening 22 is used for allowing a laser for welding the first current collecting member 4 and the first electrode tab 32 to pass through.

[0190] The second opening 22 may be provided in an area according to the welding area between the first current collecting member 4 and the first electrode tab 32. The second opening 22 may be in a circular, elliptical or polygonal shape.

[0191] During assembly, the first current collector 4 is pre-welded to the first wall 13, and then the electrode assembly 3 is installed in the outer shell 1. At this time, the first electrode tab 32 and the first current collector 4 have not yet been welded. By setting the second opening 22 on the first wall 13, the first current collector 4 and the first electrode tab 32 can be conveniently welded.

[0192] For example, the housing 1 further includes a side wall 12, and the first wall 13 is formed by the end cap 2, which is fixedly connected to the side wall 12. In this structure, the end cap 2 and the first current collector 4 are pre-welded to form an end cap assembly 2'. When assembling the battery cell 100, the end cap assembly 2' is completely covered with the first opening 11. At this time, the first current collector 4 and the first electrode tab 32 have not yet been welded. By providing the second opening 22 in the end cap 2, the first current collector 4 and the first electrode tab 32 can be conveniently welded after the end cap assembly 2' is installed.

[0193] In some embodiments, the second opening 22 and the first wall 13 have the same central axis, and the first weld 41 is located outside the second opening 22 .

[0194] Optionally, the second opening 22 is located outside the first weld 41 , and the second opening 22 is intermittently arranged along the circumference of the first wall 13 .

[0195] In this embodiment, a second opening 22 is provided in the central area of ​​the first wall 13, which can reduce the weakening of the strength of the first wall 13 and facilitate the flexible design of the welding trajectory when welding the first current collector 4 and the first tab 32, so as to realize a welding trajectory that is closed all around, which is beneficial to improving welding reliability and current flow capacity; moreover, the first weld 41 is located on the outside of the second opening 22, and when the first current collector 4 and the first wall 13 are pre-welded, the first wall 13 and the first current collector 4 can be welded at a position close to the outer edge, making the connection more reliable. Since the first current collector 4 is relatively thin, the edge area of ​​the first current collector 4 can be prevented from being deformed when subjected to external force, and even the first current collector 4 can be prevented from being separated from the first wall 13; in addition, for the embodiment in which the closing component 5 is provided at the second opening 22, when the battery cell 100 has thermal runaway, exhaust will be discharged through the first through hole 311 at the central axis of the electrode assembly 3, and the exhaust can directly act on the closing component 5 to achieve smooth opening.

[0196] In some embodiments, as shown in FIG. 4 , a second weld 42 is formed by welding the first current collecting member 4 and the first electrode tab 32 . The second weld 42 does not exceed the projection area of ​​the second opening 22 on the first current collecting member 4 .

[0197] During welding, the welding equipment emits a laser inward from the outside of the first wall 13 through the second opening 22, and the second weld 42 penetrates the first current collector 4 and extends into the first electrode tab 32. The second weld 42 in Figure 4 is only for reference, and its trajectory can be flexibly designed. For example, the trajectory of the second weld 42 can be a single ring or at least two concentric rings, or it can be a plurality of straight or curved trajectories radiating radially outward from the center, or a combination of the above two types of trajectories can be used, with an annular trajectory added to the radial trajectory to improve welding reliability. Moreover, the outermost position of the second weld 42 along the radial direction of the first current collector 4 does not exceed the projection area of ​​the second opening 22 on the first current collector 4.

[0198] Optionally, in the case of oblique laser emission, the second weld 42 may also reach the outside of the projection area of ​​the second opening 22 of the first current collecting member 4 , that is, the area where the first wall 13 blocks the first current collecting member 4 .

[0199] This embodiment can facilitate the laser welding at an angle perpendicular to the first current collecting member 4 during the welding process, without adjusting the laser emission angle, which can reduce the process difficulty and improve the reliability and firmness of the welding.

[0200] In some embodiments, as shown in FIG. 4 , the battery cell 100 further includes a sealing member 5 , which covers the second opening 22 .

[0201] The closure member 5 can be a thin plate structure, such as a 0.1 mm thick steel plate. For example, the closure member 5 can be designed in a circular, elliptical, or polygonal shape. The outer edge of the closure member 5 overlaps the outer surface of the end cap 2, and is welded in the overlapping area to form a third weld seam 51. Alternatively, the outer edge of the closure member 5 mates with the inner sidewall of the second opening 22, and is welded in the butt joint area to form a third weld seam 51.

[0202] In this embodiment, after the first electrode tab 32 and the first current collecting member 4 are welded through the second opening 22 , the second opening 22 is sealed by the sealing member 5 to prevent liquid leakage.

[0203] In some embodiments, the sealing member 5 is provided with a notch, and the notch is configured to be destroyed when the internal pressure of the battery cell 100 exceeds a preset threshold value to release the pressure.

[0204] The sealing member 5 in this embodiment acts as a pressure relief member. When the internal pressure of the battery cell 100 exceeds a preset threshold, gas flows along the first through-hole 311 toward the sealing member 5, passes through the second through-hole 43 in the center of the first current collector 4, and acts on the inner surface of the sealing member 5. The thin notch is damaged, thereby releasing pressure and improving the safety of the battery cell 100. Furthermore, the opening pressure of the pressure relief member can be flexibly set by varying the extension path and depth of the notch, allowing for precise control.

[0205] In some embodiments, the closing component 5 is welded to the first wall 13 to form a third weld 51 . The third weld 51 is configured to be broken when the internal pressure of the battery cell 100 exceeds a preset threshold value to release the pressure.

[0206] The closing component 5 in this embodiment serves as a pressure relief component. When the internal pressure of the battery cell 100 exceeds a preset threshold, the gas flows along the first through hole 311 toward the closing component 5, and passes through the second through hole 43 in the center of the first current collecting member 4 to act on the inner surface of the closing component 5, causing the closing component 5 to arch outward, thereby increasing the force at the third weld 51, destroying the third weld 51 to achieve pressure relief, and improving the safety of the battery cell 100.

[0207] Moreover, the closing component 5 is connected to the first wall 13 by welding, and the weak part is the third weld 51. The minimum thickness of the closing component 5 is the thickness of the plate itself. The thickness consistency of different areas is high, which makes it easy to ensure the opening pressure of the closing component 5. There is no need to form notches by local punching, which can reduce the problems of stress concentration and grain crushing. The steel can obtain higher strength than the base material at the weld position and is not easy to be damaged. It will only be damaged and pressure relieved under the action of high pressure of gas.

[0208] In some embodiments, as shown in FIG. 10 , the area of ​​the first wall 13 near the second opening 22 is entirely recessed inward to form a first groove 23 , and at least a portion of the closing component 5 is located in the first groove 23 .

[0209] The depth of the first groove 23 is configured such that the outer surface of the closure member 5 does not extend beyond the outer surface of the end cap 2 adjacent to the first groove 23, or such that part of the thickness of the closure member 5 is located within the first groove 23. A certain distance may be provided between the inner sidewall of the first groove 23 and the outer sidewall of the closure member 5 to facilitate installation. A transition fillet is provided at the opening of the first groove 23.

[0210] This embodiment reduces the protruding height of the closing component 5 relative to the first wall 13 by providing the first groove 23, thereby reducing the risk of deformation or damage of the closing component 5 due to external forces such as collisions, thereby improving the pressure relief reliability of the battery cell 100; moreover, when the outer shell 1 is inverted with the closing component 5 facing downward to pour the electrolyte, the outer shell 1 can also be placed more stably.

[0211] In some embodiments, as shown in FIG. 10 , the third weld 51 is spaced apart from the outer edge of the closing component 5 .

[0212] During welding, the laser first acts on the outer surface of the closing component 5 and extends inward from the bottom wall of the first groove 23. The extension trajectory of the third weld 51 is consistent with the shape of the closing component 5.

[0213] This embodiment is conducive to increasing the width of the third weld 51 to achieve the opening pressure required for the closed component 5 and improve the welding firmness and reliability; moreover, during laser welding, the welding equipment can emit laser vertically downward, which can reduce the difficulty of the welding process.

[0214] In some embodiments, as shown in FIG. 11 , the third weld 51 is formed by welding the outer edge of the closing component 5 and the bottom wall of the first groove 23 .

[0215] During welding, the laser is applied to the corner area formed between the outer edge of the closure member 5 and the bottom wall of the first groove 23, achieving a fillet weld. The third weld 51 may fully or partially penetrate the outer edge of the closure member 5. When laser welding is employed, the welding equipment may emit the laser at an angle relative to the closure member 5. After welding, a portion of the third weld 51 is deposited at the corner area formed between the outer edge of the closure member 5 and the bottom wall of the first groove 23. Another portion extends inward from the outer side wall of the closure member 5 and extends obliquely within the bottom wall of the first groove 23, without exceeding the bottom wall of the first groove 23, thereby increasing the strength of the connection. The third weld 51 extends continuously along the outer edge of the closure member 5.

[0216] This embodiment facilitates determining the trajectory of the third weld 51 and directly performs welding along the outer edge of the closing component 5, which can reduce the difficulty of the process; moreover, a portion of the third weld 51 is accumulated in the corner area formed between the outer edge of the closing component 5 and the bottom wall of the first groove 23, which can improve the welding reliability and strength.

[0217] In some embodiments, as shown in FIG12 , a second groove 24 is provided on the bottom wall of the first groove 23 , the closing component 5 is provided in the second groove 24 , and the third weld 51 is formed by welding the outer edge of the closing component 5 to the side wall of the second groove 24 .

[0218] The outer edge of the closing component 5 may abut against the inner sidewall of the second groove 24 , or there may be a gap between the outer edge of the closing component 5 and the inner sidewall of the second groove 24 .

[0219] During welding, the laser acts between the outer edge of the closing component 5 and the inner side wall of the second groove 24 to achieve butt welding. The third weld 51 can penetrate the outer edge of the closing component 5 and extend into the bottom wall of the second groove 24. The third weld 51 can extend continuously along the outer edge of the closing component 5.

[0220] In this embodiment, the sealing component 5 is disposed in the second groove 24 , so that the sealing component 5 can be further retracted inward relative to the outer surface of the first wall 13 , thereby preventing the sealing component 5 from being deformed or damaged by external forces such as collisions, thereby improving the pressure relief reliability of the battery cell 100 .

[0221] In some embodiments, as shown in FIG. 13 , a thinned portion 53 is provided on the outer periphery of the closing component 5 , and the thinned portion 53 overlaps the first wall 13 .

[0222] The sealing component 5 can be thinned by removing material from the outer surface or the inner surface, or by removing material from both the inner and outer surfaces.

[0223] This embodiment features a thinned portion 53 around the periphery of the sealing member 5, making it easier to penetrate the thinned portion 53 during welding, improving weld strength and reliability. Furthermore, the sealing member 5 is locally thinned at the edges and thickened in the center, enhancing overall strength and preventing deformation caused by gassing within the battery cell 100.

[0224] In some embodiments, a third groove 52 is provided on the inner surface of the closing component 5 near the outer edge, so that a thinned portion 53 is formed on the outer edge of the closing component 5 .

[0225] The thinned portion 53 overlaps the outer surface of the first wall 13 at a position adjacent to the second opening 22. In Figure 12 , when the closure member 5 shown in Figure 13 is installed, the thinned portion 53 overlaps the bottom wall of the third groove 52, and the portion of the closure member 5 within the thinned portion 53 is embedded in the second opening 22. The thinned portion 53 can be achieved by partial upsetting.

[0226] This embodiment facilitates the cooperation between the central thickened portion of the closing component 5 and the second opening 22, and can play a positioning role. No additional positioning is required when welding the closing component 5, and the closing component 5 will not be misplaced during the welding process, thereby improving welding reliability.

[0227] In some embodiments, as shown in FIG. 14 , a reinforcing rib 54 is provided on the closing component 5 , and the reinforcing rib 54 protrudes toward the first current collecting member 4 .

[0228] The reinforcing rib 54 can be realized by stamping the end cover 2 . The reinforcing rib 54 can be an annular structure protruding toward the first current collecting member 4 along the circumference of the closing component 5 . The cross section of the reinforcing rib 54 can be arc-shaped.

[0229] This embodiment provides reinforcing ribs 54 on the sealing member 5 to enhance its overall strength and prevent deformation due to external forces or gas generation within the battery cells 100. Furthermore, the ribs 54 protrude toward the first current collector 4, preventing deformation or damage to the sealing member 5 caused by external forces such as collisions.

[0230] In some embodiments, as shown in FIG. 3 and FIG. 5 , the electrode assembly 3 further includes a second electrode tab 33 , and the second electrode tab 33 and the first electrode tab 32 are respectively led out from two ends of the electrode body 31 .

[0231] Optionally, the second electrode tab 33 and the first electrode tab 32 may also be led out from the same end of the electrode body 31 . Accordingly, the closing component 5 is located on the second wall 14 of the housing 1 opposite to the first wall 13 .

[0232] In this embodiment, the second electrode tab 33 and the first electrode tab 32 are respectively led out from the two ends of the electrode body 31, and the second opening 22 on the first wall 13 can be used to weld the closing component 5, which has a simple structure; and can increase the connection area between the electrode tab on each side and the current collector, thereby improving the flow capacity and optimizing the performance of the battery cell 100.

[0233] In some embodiments, the battery cell 100 further includes an electrode terminal 8 and a second current collector 6 , the housing 1 further includes a side wall 12 and a second wall 14 arranged opposite to the first wall 13 , the electrode terminal 8 is insulated and arranged on the second wall 14 , and the electrode terminal 8 is electrically connected to the second electrode tab 33 through the second current collector 6 .

[0234] Among them, the electrode terminal 8 is insulated from the second wall 14 by the first insulating member 9, and the opening for installing the electrode terminal 8 can be sealed. A fourth groove 81 is provided on the outer surface of the electrode terminal 8, and a liquid injection hole 82 is provided on the bottom wall of the fourth groove 81. The second current collector 6 is welded to the second tab 33, and the bottom wall of the fourth groove 81 is welded to the second current collector 6. After the liquid injection is completed, the fourth groove 81 is closed by a cover plate 83. An insulating plate 7 may be provided on the inner surface of the second wall 14 to achieve insulation between the second current collector 6 and the second wall 14. In addition, the second tab 33 and the second current collector 6 can be wrapped by an L-shaped second insulating member 10 to achieve insulation from the outer shell 1.

[0235] In this embodiment, the electrode terminal 8 is provided on the second wall 14 of the housing 1 . When the second electrode tab 33 and the first electrode tab 32 are led out from both ends of the electrode body 31 , they can be conveniently electrically connected to the electrode terminal 8 and the end cap 2 respectively.

[0236] In some embodiments, the housing 1 includes a container 1 ′ and an end cover 2 . The end cover 2 is fixedly connected to the first opening 11 of the container 1 ′, and the first wall 13 is the end cover 2 .

[0237] The housing 1 may include a side wall 12, a first wall 13, and a second wall 14, with the first wall 13 and the second wall 14 respectively connected to opposite ends of the side wall 12. The side wall 12 serves as the side wall of the container 1', and the first wall 13 serves as the end cap 2. If the end of the container 1' opposite the first opening 11 is closed, the second wall 14 may be integrally formed with the side wall 12. If the end of the container 1' opposite the first opening 11 is open, it may be closed by an end cap, and the second wall 14 also serves as the end cap.

[0238] The first current collecting part 4 is connected to the inner surface of the end cover 2 by a first weld 41. During welding, the welding equipment is operated from the side of the first current collecting part 4 away from the end cover 2. In order to facilitate welding, the end cover 2 can be inverted on the working platform, and the first current collecting part 4 can be positioned at a suitable position on the first wall 13. The first current collecting part 4 can be supported by the end cover 2 or other tooling.

[0239] During assembly of the battery cell 100, this embodiment pre-welds the first current collector 4 and the end cap 2 to form an end cap assembly 2'. This differs from the conventional method of welding the end cap to the current collector from the outside after installation. Furthermore, even if cracks appear at the first weld seam 41 after cooling, the cracks are located inside the end cap 2, preventing electrolyte leakage through the weld seam and out of the end cap 2, thereby improving the reliability of the battery cell 100 during use. In particular, when the first current collector 4 and the end cap 2 are made of different materials, the large difference in thermal expansion coefficients after cooling makes the two materials contract more likely to cause weld cracks. Locating the first weld seam 41 inside the end cap 2 can better address leakage, thereby reducing the material requirements for the first current collector 4 and the end cap 2. Furthermore, pre-welding the first current collector 4 and the end cap 2 eliminates the need for welding within the cavity of the housing 1, making welding easier and more convenient.

[0240] The structure and assembly method of the battery cell 100 of the present application will be described below through a specific embodiment.

[0241] As shown in Figures 3 and 4, the battery cell 100 is cylindrical and includes: an outer shell 1, an electrode assembly 3, a first current collector 4, a sealing member 5, a second current collector 6, and an electrode terminal 8. The outer shell 1 includes a container 1' and an end cap 2. The container 1' has a first opening 11. The end cap 2 is used to cover the first opening 11. A second opening 22 is provided at the central axis of the end cap 2. The second opening 22 is sealed by a sealing member 5. A third weld 51 is formed between the sealing member 5 and the end cap 2. The end cap 2 has a body 20 and a connecting portion 21. The connecting portion 21 protrudes relative to the body 20 toward the first current collector 4 along the thickness direction of the end cap 2. The connecting portion 21 is located near the outer edge of the end cap 2 and is arranged along the entire circumference of the end cap 2. The connecting portion 21 has a U-shaped cross-section and protrudes as a whole toward the first current collector 4.

[0242] The electrode assembly 3 includes an electrode body 31 and first and second tabs 32, 33 extending from each end of the electrode body 31. For example, the first and second tabs 32, 33 can be closed ring structures, or rectangular or fan-shaped structures spaced apart circumferentially around the electrode body 31. The first current collector 4 can be a circular thin sheet sandwiched between the connecting portion 21 and the first tab 32. A first weld 41 is formed between the first current collector 4 and the connecting portion 21, and the first weld 41 does not penetrate the outer surface of the end cap 2. The first current collector 4 is spaced apart from the area of ​​the main body 20 radially inward of the connecting portion 21, along the height of the battery cell 100. A first through-hole 311 is provided in the center of the electrode body 31, and a second through-hole 43 is provided in the center of the first current collector 4 to allow exhaust gas to act on the sealing member 5 in the event of thermal runaway of the battery cell 100. The electrode terminal 8 is insulated and disposed on the second wall 14. The electrode terminal 8 is electrically connected to the second tab 33 via the second current collector 6. The outer surface of the electrode terminal 8 is provided with a fourth groove 81, the bottom wall of which is provided with a liquid injection hole 82. The second current collector 6 is welded to the second electrode tab 33, and the bottom wall of the fourth groove 81 is welded to the second current collector 6. After liquid injection is completed, the fourth groove 81 is sealed with a cover plate 83.

[0243] When assembling the battery cell 100, first, the end cover 2 and the first current collector 4 are welded from one side of the first current collector 4 to form an end cover assembly 2'; secondly, the electrode terminal 8 is installed on the second wall 14 of the outer shell 1, and the electrode terminal 8 and the second wall 14 are insulated by the first insulating member 9, and the insulating plate 7 is installed on the inner surface of the second wall 14; then, the second current collector 6 and the second tab 33 are welded, and the L-shaped second insulating member 10 is wrapped around the position of the electrode assembly 3 and the second current collector 6, and placed in the outer shell 1; then, the end cover assembly 2' is covered on the first opening 11, and the outer edge of the end cover 2 is welded to the first opening 11 of the accommodating member 1', and the first current collector 4 is welded to the first tab 32 through the second opening 22. The order of these two welding steps can be interchanged, and then the closing component 5 is welded; finally, the outer shell 1 is inverted, the electrode terminal 8 and the second current collector 6 are welded, and the cover plate 83 is closed after the electrolyte is injected through the injection hole 82.

[0244] Secondly, the present application provides a method for manufacturing a battery cell, as shown in FIG15 , which, in some embodiments, includes:

[0245] S110, providing an assembly step: providing a container 1', an end cap assembly 2', and an electrode assembly 3, wherein the electrode assembly 3 includes an electrode body 31 and a first electrode tab 32, the first electrode tab 32 extending from the electrode body 31, and the end cap assembly 2' includes an end cap 2 and a first current collector 4, wherein the first current collector 4 is connected to the inner surface of the end cap 2 via a first weld 41, and the first weld 41 does not penetrate the outer surface of the end cap 2;

[0246] S120, electrode placement step: placing the electrode assembly 3 into the container 1' through the first opening 11 of the container 1';

[0247] S130, end cap sealing step: closing the end cap assembly 2' on the first opening 11; and

[0248] S140 , electrical connection step: electrically connecting the first current collecting member 4 to the first electrode tab 32 .

[0249] Among them, S110 to S140 are executed sequentially.

[0250] In this embodiment of the battery cell 100, the first current collector 4 is welded to the end cap 2 from the inside of the end cap 2, and the first weld 41 does not penetrate the outer surface of the end cap 2. Compared to welding from the outside of the end cap 2 and melting throughout the entire thickness, even if cracks appear at the first weld 41 after the weld cools, the cracks are located on the inside of the end cap 2, preventing electrolyte leakage through the weld and out of the end cap 2, thereby improving the reliability of the battery cell 100 during use. In particular, when the first current collector 4 and the end cap 2 are made of different materials, after cooling, the large difference in thermal expansion coefficients between the two materials causes inconsistent contraction, which makes weld cracks more likely to occur. Locating the first weld 41 on the inside of the end cap 2 can better prevent leakage, thereby reducing the material requirements for the first current collector 4 and the end cap 2.

[0251] In some embodiments, the end cap 2 has a second opening 22 , and the electrical connection step S140 includes:

[0252] The laser passes through the second opening 22 to weld the first current collecting member 4 and the first electrode tab 32 .

[0253] The second opening 22 in this embodiment forms a channel for laser welding the first current collector 4 and the first pole tab 32. Since the end cover 2 and the first current collector 4 are pre-welded to form the end cover assembly 2', when assembling the battery cell 100, the end cover assembly 2' is completely covered on the first opening 11. At this time, the first current collector 4 and the first pole tab 32 have not yet been welded. By providing the second opening 22 on the end cover 2, the first current collector 4 and the first pole tab 32 can be conveniently welded after the end cover assembly 2' is installed.

[0254] In some embodiments, the end cap assembly 2' further includes a sealing component 5. After the negative electrode electrical connection step S140, the manufacturing method further includes:

[0255] The closing component 5 is made to cover the second opening 22 , and the closing component 5 and the end cover 2 are welded to form a third weld 51 .

[0256] The closing component 5 can cover the second opening 22 from the outside of the end cover 2 , and the third weld 51 is configured to be destroyed when the internal pressure of the battery cell 100 exceeds a preset threshold value to release the pressure.

[0257] The second opening 22 of this embodiment can be used for welding the first electrode tab 32 and the first current collecting member 4 . After welding is completed, the second opening 22 is sealed by welding the closing component 5 to achieve sealing of the housing 1 .

[0258] In some embodiments, after the end cap sealing step S130, the manufacturing method further comprises:

[0259] The outer edge of the end cap 2 is connected to the receiving part 1 ′ at the first opening 11 .

[0260] The order of executing this step and the negative electrode electrical connection step S140 is interchangeable. If the end cap 2 is connected to the container 1' first, the first current collector 4 can be reliably contacted with the first electrode tab 32, and then the negative electrode electrical connection step S140 is performed. This improves the reliability of the electrical connection between the first current collector 4 and the first electrode tab 32. If the negative electrode electrical connection step S140 is performed first, and then the end cap 2 is connected to the container 1', the first current collector 4 and the first electrode tab 32 can be welded under appropriate contact pressure. The gap between the outer edge of the end cap 2 and the first opening 11 of the container 1' can be compensated by the weld, which can prevent the end cap assembly 2' from applying excessive pressure on the first electrode tab 32 and reduce deformation of the first electrode tab 32.

[0261] For example, as shown in Figure 4, the end cap 2 can overlap the end of the container 1', and the outer edge of the end cap 2 can be welded to the end of the container 1'. The end cap 2 has a connecting portion 21 that protrudes toward the first current collecting member 4 to form a U-shaped structure. The outer sidewall of the connecting portion 21 cooperates with the sidewall 12 of the container 1' to ensure positioning.

[0262] This embodiment can reliably seal the container 1 ′ with the end cover 2 , preventing the electrolyte from leaking from the connection between the end cover 2 and the container 1 ′.

[0263] 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 (1) comprising a first wall (13); An electrode assembly (3) is arranged in the housing (1), the electrode assembly (3) comprising an electrode body (31) and a first electrode tab (32), the first electrode tab (32) being led out from the electrode body (31); and A first current collecting member (4) is used to electrically connect the first electrode tab (32) and the first wall (13); the first current collecting member (4) is connected to the inner surface of the first wall (13) via a first weld (41), and the first weld (41) does not penetrate the outer surface of the first wall (13).

2. The battery cell according to claim 1, wherein: The first welding seam (41) penetrates the first current collecting member (4).

3. The battery cell according to claim 1 or 2, wherein: At least a portion of the first current collecting member (4) is sandwiched between the first electrode tab (32) and the first wall (13).

4. The battery cell according to claim 3, wherein: The first welding seam (41) is spaced apart from the outer edge of the first current collecting member (4).

5. The battery cell according to claim 3, wherein: The first welding seam (41) is formed by welding the outer edge of the first current collecting member (4) and the inner surface of the first wall (13).

6. The battery cell according to any one of claims 1 to 3, wherein: The first wall (13) comprises a main body portion (20) and a connecting portion (21), wherein the connecting portion (21) protrudes relative to the main body portion (20) toward the first current collecting member (4) along the thickness direction of the first wall (13), and the connecting portion (21) is in contact with the first current collecting member (4), and the first weld (41) is formed by welding the first current collecting member (4) and the connecting portion (21).

7. The battery cell according to claim 6, wherein: The first wall (13) has a recessed portion (25), the inner side wall of the connecting portion (21) and the inner surface of the main body (20) define the recessed portion (25), the first current collecting piece (4) is at least partially located in the recessed portion (25), and the first weld (41) is formed by welding the outer edge of the first current collecting piece (4) and the inner side wall of the connecting portion (21).

8. The battery cell according to claim 7, wherein: Along the thickness direction of the first wall (13), the surface of the first current collecting member (4) facing the electrode assembly (3) is closer to the electrode assembly (3) than the inner surface of the bottom wall of the connecting portion (21).

9. The battery cell according to claim 6, wherein: The first welding seam (41) is formed by welding the first current collecting member (4) and the bottom wall of the connecting portion (21).

10. The battery cell according to any one of claims 1 to 9, wherein: The first current collecting member (4) comprises a first portion (44) and a second portion (45) which are connected to each other, wherein the first portion (44) is used for welding to the first wall (13), and the second portion (45) is used for welding to the first electrode tab (32).

11. The battery cell according to claim 10, wherein: The thickness of the first portion (44) is smaller than the thickness of the second portion (45).

12. The battery cell according to claim 10 or 11, wherein: The thickness of the first portion (44) is smaller than the thickness of the welding area between the first wall (13) and the first portion (44).

13. The battery cell according to any one of claims 1 to 12, wherein: The first current collecting member (4) and the first wall (13) are made of different materials.

14. The battery cell according to any one of claims 1 to 13, wherein: The first current collector (4) is a negative electrode current collector, the first current collector (4) comprises a copper material, and the first wall (13) comprises a steel material.

15. The battery cell according to any one of claims 1 to 14, wherein: The first wall (13) has a second opening (22), and the second opening (22) is used for allowing a laser for welding the first current collecting member (4) and the first electrode tab (32) to pass through.

16. The battery cell according to claim 15, wherein: The second opening (22) and the first wall (13) have the same central axis, and the first welding seam (41) is located outside the second opening (22).

17. The battery cell according to claim 15 or 16, wherein: The first current collecting member (4) and the first pole tab (32) are welded to form a second weld seam (42), and the second weld seam (42) does not exceed a projection area of ​​the second opening (22) on the first current collecting member (4).

18. The battery cell according to any one of claims 15 to 17, further comprising a closing member (5), wherein the closing member (5) covers the second opening (22).

19. The battery cell according to claim 18, wherein: The sealing component (5) is provided with a notch, and the notch is configured to be destroyed when the internal pressure of the battery cell (100) exceeds a preset threshold value, so as to release the pressure.

20. The battery cell according to claim 18, wherein: The closing component (5) is welded to the first wall (13) to form a third weld (51), and the third weld (51) is configured to be destroyed when the internal pressure of the battery cell (100) exceeds a preset threshold value to release pressure.

21. The battery cell according to claim 20, wherein: The third weld seam (51) is spaced apart from the outer edge of the closing component (5).

22. The battery cell according to claim 20, wherein: The area of ​​the first wall (13) close to the second opening (22) is concave inward as a whole to form a first groove (23), and the closing component (5) is at least partially located in the first groove (23).

23. The battery cell according to claim 22, wherein: The third weld seam (51) is formed by welding the outer edge of the closing component (5) and the bottom wall of the first groove (23).

24. The battery cell according to claim 22, wherein: The bottom wall of the first groove (23) is provided with a second groove (24), the closing component (5) is arranged in the second groove (24), and the third weld (51) is formed by welding the outer edge of the closing component (5) and the side wall of the second groove (24).

25. The battery cell according to any one of claims 18 to 24, wherein: A thinned portion (53) is provided on the outer periphery of the closing component (5), and the thinned portion (53) overlaps the first wall (13).

26. The battery cell according to claim 25, wherein: The inner surface of the closing component (5) is provided with a third groove (52) in a region close to the outer edge, so that the outer edge of the closing component (5) forms the thinned portion (53).

27. The battery cell according to any one of claims 18 to 26, wherein: The closing component (5) is provided with a reinforcing rib (54), and the reinforcing rib (54) protrudes toward the first current collecting member (4).

28. The battery cell according to any one of claims 1 to 27, wherein: The electrode assembly (3) further comprises a second electrode tab (33), wherein the second electrode tab (33) and the first electrode tab (32) are respectively led out from two ends of the electrode body (31).

29. The battery cell according to claim 28, further comprising an electrode terminal (8) and a second current collector (6), the housing (1) further comprising a side wall (12) and a second wall (14) arranged opposite to the first wall (13), the electrode terminal (8) being insulated and arranged on the second wall (14), and the electrode terminal (8) being electrically connected to the second pole lug (33) via the second current collector (6).

30. The battery cell according to any one of claims 1 to 29, wherein: The housing (1) comprises a container (1') and an end cover (2); the end cover (2) is fixedly connected to a first opening (11) of the container (1'); and the first wall (13) is the end cover (2).

31. A battery, comprising the battery cell (100) according to any one of claims 1 to 30.

32. An electrical device, comprising the battery cell (100) according to any one of claims 1 to 30 and / or the battery (200) according to claim 31, for providing electrical energy to the electrical device.

33. A method for manufacturing a battery cell, comprising: Providing an assembly step: providing a container (1'), an end cap assembly (2') and an electrode assembly (3), wherein the electrode assembly (3) comprises an electrode body (31) and a first electrode tab (32), wherein the first electrode tab (32) is led out from the electrode body (31), and the end cap assembly (2') comprises an end cap (2) and a first current collector (4), wherein the first current collector (4) is connected to the inner surface of the end cap (2) via a first weld (41), and the first weld (41) does not penetrate the outer surface of the end cover (2); Electrode placement step: placing the electrode assembly (3) into the container (1') from the first opening (11) of the container (1'); End cap sealing step: covering the end cap assembly (2') on the first opening (11); Electrical connection step: electrically connecting the first current collecting member (4) to the first electrode tab (32).

34. The manufacturing method according to claim 33, wherein: The end cover (2) has a second opening (22), and the electrical connection step comprises: The laser is used to weld the first current collecting member (4) and the first electrode tab (32) through the second opening (22).

35. The manufacturing method according to claim 34, wherein: The end cap assembly (2') further comprises a sealing component (5). After the electrical connection step, the manufacturing method further comprises: The closing component (5) is made to cover the second opening (22), and the closing component (5) and the end cover (2) are welded to form a third weld (51).

36. The manufacturing method according to any one of claims 33 to 35, wherein: After the end cap sealing step, the manufacturing method further comprises: The outer edge of the end cover (2) is connected to the container (1') at the first opening (11).

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