Battery cell, battery and electric device

Abstract

The embodiment of the invention provides a battery monomer, a battery and a power utilization device. The battery cell includes an electrode assembly, a case, an electrode terminal, and a current collecting member. The electrode assembly includes a first tab. The case is used for accommodating the electrode assembly. The electrode terminal is arranged on the shell and comprises a first concave part and a connecting part located at the bottom of the first concave part. The current collecting component is connected to the first tab and is welded with the connecting part; the first concave part is arranged on the electrode terminal to reduce the thickness of the connecting part, so that the welding power required by welding the connecting part and the current collecting component is reduced, heat production is reduced, the risk that other components are burnt is reduced, and the safety is improved.

Description

[0001] This application is a divisional application of the invention patent application filed on August 22, 2022, with application number 202280007871.9 (PCT / CN2022 / 114037) and entitled "Battery cell, battery and electrical device".

[0002] Among them, the invention patent application filed on August 22, 2022, with application number 202280007871.9 (PCT / CN2022 / 114037) and entitled "Battery cell, battery and electrical device", claims priority to the application filed on August 23, 2021, entitled "Battery cell and manufacturing method and manufacturing system thereof, battery and electrical device", with international application number PCT / CN2021 / 114156, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery, and an electrical device. Background Technology

[0004] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and rechargeable alkaline zinc-manganese battery cells, among others.

[0005] In the development of battery technology, improving the safety of individual battery cells is a key research direction. Summary of the Invention

[0006] This application provides a battery cell, a battery, and an electrical device that can improve the safety of the battery cell.

[0007] In a first aspect, embodiments of this application provide a battery cell, including an electrode assembly, a housing, electrode terminals, and a current collector. The electrode assembly includes a first tab. The housing is used to house the electrode assembly. The electrode terminals are disposed in the housing, and each electrode terminal includes a first recess and a connecting portion located at the bottom of the first recess. The current collector is connected to the first tab and welded to the connecting portion.

[0008] In the above technical solution, by opening a first recess on the electrode terminal to reduce the thickness of the connection part, the welding power required for welding the connection part to the current collector is reduced, heat generation is reduced, the risk of other components being burned is reduced, and safety is improved.

[0009] In some embodiments, the current collector is welded to the connector to form a first welded portion, which extends at least into the interior of the current collector from the side of the connector away from the current collector in the thickness direction of the connector.

[0010] In the above technical solution, the first welding part extends from the connecting part into the interior of the current collector to connect the current collector and the connecting part, thereby reducing the contact resistance between the current collector and the electrode terminal and improving the current carrying capacity.

[0011] In some embodiments, in the thickness direction of the connection, the first weld portion does not extend beyond the surface of the current collector member away from the connection portion.

[0012] In the above technical solution, the first welded part is spaced at a predetermined distance from the surface of the current collector that is away from the connection part, so as to avoid the current collector being melted through, reduce the risk of metal particles being generated on the surface of the current collector that is away from the connection part, and improve safety.

[0013] In some embodiments, the housing includes a cylindrical body and a cover connected to the cylindrical body. The cylindrical body surrounds the outer periphery of the electrode assembly, and the cover has an electrode lead-out hole, on which electrode terminals are mounted. Both the first welding portion and the cover are annular. The outer diameter of the cover is D0, and the inner diameter of the first welding portion is D1. D1 and D0 satisfy: 0.1 ≤ D1 / D0 ≤ 0.6.

[0014] D0 is positively correlated with the diameter of the electrode assembly. The larger D0 is, the higher the capacity of the electrode assembly, and the higher the requirement for the current-carrying area of ​​the first welding part in the battery cell. The smaller D1 is, the smaller the perimeter of the first welding part, and the smaller the current-carrying area of ​​the first welding part. If D1 / D0 is too small, then due to D0 being too large and D1 being too small, the current-carrying area of ​​the first welding part will be insufficient. The first welding part will generate more heat during charging and discharging, making it difficult to meet the requirements of the battery cell for current capacity and temperature rise during fast charging.

[0015] The larger D1 is, the larger the size of the electrode lead-out hole and the smaller the area of ​​the cover. Similarly, the smaller D0 is, the smaller the area of ​​the cover. If D1 / D0 is too large, the cover will easily deform when the battery cell vibrates due to the small size of D0 and the large size of D1, causing a safety hazard. The cover can serve as an output terminal of the battery cell to connect to the busbar. If D1 / D0 is too large, the connection area between the cover and the busbar will be too small, resulting in insufficient current flow area and excessive heat generation at the connection point, making it difficult to meet the requirements of the battery cell for current flow capacity and temperature rise during fast charging.

[0016] The above technical solution ensures that 0.1≤D1 / D0≤0.6, thereby meeting the requirements of battery cells for overcurrent capacity and temperature rise, and improving the safety of battery cells.

[0017] In some embodiments, the first welded part is a non-closed structure, and the central angle α of the first welded part is 180°-330°.

[0018] α is positively correlated with the current-carrying area of ​​the first weld. The smaller α is, the smaller the current-carrying area of ​​the first weld, and the higher the heat generated when current flows through the first weld. The above technical solution limits α to 180°-330° to ensure that the first weld meets the requirements of the battery cell for current carrying capacity and temperature rise. The first weld is a non-enclosed structure, and the unwelded area between the two ends of the first weld along the circumferential direction can release welding stress and reduce stress concentration.

[0019] In some embodiments, the first weld portion is a closed structure to increase the welding area and improve the welding strength and flow capacity of the first weld portion.

[0020] In some embodiments, 0.2 ≤ D1 / D0 ≤ 0.4

[0021] In some embodiments, D1 is 5mm-14mm to meet the requirements of the battery cell for overcurrent capacity and temperature rise.

[0022] In some embodiments, the cover and the cylinder are integrally formed, thus eliminating the need for a connection process between them. When the cover and the cylinder are electrically connected to the positive or negative terminal of the electrode assembly, the resistance at the connection point is low due to the integral structure, thereby improving current carrying capacity. The cover can be used to connect to external components (such as busbars). When a battery cell is subjected to external impact, the external component may pull on the cover, causing force to be applied to the connection point between the cover and the cylinder. The above technical solution integrates the cover and the cylinder, thereby increasing the strength of the connection point and reducing the risk of connection failure.

[0023] In some embodiments, in the thickness direction of the connection, the dimension of the first welded portion is h, and the thickness of the area of ​​the connection for welding with the current collecting member is d0. d0 and h satisfy: 1 ​​< h / d0 ≤ 1.5.

[0024] If h / d0 ≤ 1, the penetration depth of the first weld is small, and the first weld is formed entirely at the connection, resulting in a weak weld. The first weld is then unable to effectively connect the current collector and the connection. When d0 is constant, the larger h is, the greater the power required for welding and the higher the heat generated during the welding process. If h is too large, the high temperature generated during welding can easily damage components around the electrode terminals, causing safety hazards.

[0025] The above technical solution ensures that 1 < h / d0 ≤ 1.5, thereby reducing welding heat generation and lowering welding difficulty while ensuring the connection between the current collection component and the connecting part.

[0026] In some embodiments, the thickness of the area of ​​the current collector for welding with the connection is d1, d0 and d1 satisfy: 0.5≤d1 / d0≤1.2.

[0027] When d0 is constant, the smaller d1 is, the easier it is for the current collector to be melted through during the welding process, and the easier it is for the high-temperature particles generated during welding to fall into the battery cell; the larger d1 is, the larger the space and weight occupied by the current collector, and the lower the energy density of the battery cell.

[0028] The above technical solution ensures that 0.5≤d1 / d0≤1.2, thereby reducing the risk of current collector components being melted through and reducing the loss of energy density of individual battery cells.

[0029] In some embodiments, d0 is 0.4mm-1.2mm to meet the requirements of battery cells for overcurrent capacity and temperature rise, reduce welding heat generation, and improve safety.

[0030] In some embodiments, at least a portion of the first tab is located on the side of the current collector opposite to the electrode terminal and is supported on the current collector.

[0031] In the above technical solution, the first tab can support the current collector, allowing it to fit snugly against the connecting portion. When the battery cell vibrates, the first tab can restrict the movement of the current collector relative to the connecting portion, thereby reducing the stress on the first weld and lowering the risk of tearing. When welding the connecting portion and the current collector, the first tab can support the current collector, thereby reducing the relative displacement between the current collector and the connecting portion during the welding process and lowering the risk of incomplete welding.

[0032] In some embodiments, a first portion of the first tab is located on the side of the connector opposite to the first recess and is used to support the portion of the current collector opposite to the connector.

[0033] In the above technical solution, the first part can support the portion of the current collector that is opposite to the connecting part, so that the current collector and the connecting part fit tightly together, reducing the risk of incomplete welding. During the welding process, the first part can also limit the deformation of the current collector and improve the morphology of the current collector.

[0034] In some embodiments, the first portion is welded to the current collector and forms a second welded portion.

[0035] In the above technical solution, the second welded portion can reduce the contact resistance between the current collector and the first tab, thereby improving the current carrying capacity. The second welded portion is close to the connecting portion, which reduces the conductive path between the connecting portion and the second welded portion, thus reducing resistance and improving the current carrying capacity.

[0036] In some embodiments, a second portion of the first tab surrounds the outer periphery of the first portion and is used to support the area of ​​the current collector that is not opposite to the connecting portion.

[0037] In the above technical solution, by setting the second part, the area of ​​the region supporting the current collection component of the first electrode ear can be increased, the supporting effect of the first electrode ear can be improved, the pressure between the first electrode ear and the current collection component can be reduced, and the risk of the first electrode ear being crushed can be reduced.

[0038] In some embodiments, the second portion is welded to the current collector and forms a third welded portion.

[0039] In the above technical solution, the third welding part can reduce the contact resistance between the current collecting component and the second part, thereby improving the current carrying capacity.

[0040] In some embodiments, the current collector has a protrusion on the side facing the first electrode tab, and the protrusion is welded to the second portion to form a third weld portion.

[0041] In the above technical solution, the protrusion can fit better with the second part, reducing the risk of poor welding.

[0042] In some embodiments, the first electrode tab is arranged around the central axis of the electrode assembly, and the cross-section of the first electrode tab perpendicular to the central axis is annular. The outer radius of the first electrode tab is R, and the minimum radial distance between the third welding part and the central axis of the first electrode tab is D2, both satisfying: 0.2≤D2 / R≤0.8.

[0043] R is positively correlated with the diameter of the electrode assembly. The larger R is, the greater the current generated by the electrode assembly, and the higher the requirement for the current-carrying area of ​​the battery cell. The portion of the current collector near the central axis can be used for welding to the connection part; the smaller D2 is, the smaller the area of ​​the current collector that can be welded to the connection part, and the smaller the current-carrying area between the current collector and the connection part. If D2 / R is too small, then due to the small D2 and large R, the current-carrying area between the current collector and the connection part will be insufficient. The weld between the current collector and the connection part will generate more heat during charging and discharging, making it difficult to meet the requirements of the battery cell for current carrying capacity and temperature rise during fast charging.

[0044] The first tab comprises multiple tab layers. The larger D2 is, the outermost tab layer is directly connected to the third welding part. If D2 is too large, it will result in fewer tab layers connected to the third welding part, and the distance between the third welding part and the innermost tab layer will be too large. This will cause a large difference between the current path between the outermost tab layer and the electrode terminal and the current path between the innermost tab layer and the electrode terminal, leading to uneven current density in the first electrode and increased internal resistance.

[0045] The above technical solution limits D2 / R to 0.2-0.8 to reduce the difference in current path between different positions of the first tab and the electrode terminal, improve the uniformity of current density of the first electrode plate of the electrode assembly, reduce internal resistance, and meet the requirements of the battery cell for overcurrent capacity and temperature rise.

[0046] In some embodiments, D2 and R satisfy: 0.2≤D2 / R≤0.5.

[0047] In some embodiments, D2 is 3.5mm-10mm to reduce the internal resistance of the electrode assembly and meet the requirements of the battery cell for overcurrent capacity and temperature rise.

[0048] In some embodiments, the diameter of the current collector is D3, and the diameter of the first electrode tab is D4, where D3 is smaller than D4.

[0049] In the above technical solution, the current collector has a smaller diameter, which can save the space and weight occupied by the current collector and improve the energy density of the battery cell.

[0050] In some embodiments, D3 and D4 satisfy: 0.75≤D3 / D4≤0.97.

[0051] When D4 is constant, if D3 is too small, the distance between the outer part of the first electrode tab and the current collector will be too large, resulting in an excessively long conductive path between them. This leads to a high internal resistance of the electrode assembly, affecting the performance of the individual battery cell. The above technical solution achieves D3 / D4 ≥ 0.75 to reduce the internal resistance of the electrode assembly and improve the charge and discharge performance of the individual battery cell.

[0052] If D3 is too large when D4 is constant, the coaxiality of the current collector and the electrode assembly will fluctuate due to assembly errors, causing the current collector to protrude from the outer circumferential surface of the electrode assembly. This makes it difficult for the current collector and the electrode assembly to fit into the housing, affecting assembly efficiency and product yield.

[0053] When D4 is constant, if D3 is too large, the coaxiality of the current collector and the electrode assembly will fluctuate due to assembly errors. This can cause the current collector to protrude from the outer circumference of the electrode assembly, making it difficult to fit the current collector and electrode assembly into the housing, thus affecting assembly efficiency and product yield. The above technical solution ensures that D3 / D4 ≤ 0.97, reducing the risk of the current collector protruding from the outer circumference of the electrode assembly due to errors, thereby improving assembly efficiency and product yield.

[0054] In some embodiments, D3 is 35mm-44mm. Limiting D3 to 35mm-44mm can reduce the internal resistance of the electrode assembly, improve the charge and discharge performance of the battery cell, and reduce the risk of the current collector protruding from the outer peripheral surface of the electrode assembly due to errors.

[0055] In some embodiments, the connector has a groove recessed from the first outer surface of the connector in the direction facing the electrode assembly, and the first welding portion extends from the bottom wall of the groove to at least the interior of the current collector.

[0056] During the production of battery cells, external equipment needs to cooperate with the connecting parts. The surface of the first welding part is uneven, and if the external equipment is pressed onto the first welding part, it is easily damaged by the first welding part. The above technical solution creates a groove to form a gap between the first outer surface and the bottom wall of the groove. In this way, the first outer surface can be used to support the external equipment, thus separating the external equipment from the first welding part and reducing the risk of the external equipment being damaged.

[0057] In some embodiments, the housing includes a cylindrical body and a cover connected to the cylindrical body. The cylindrical body surrounds the outer periphery of the electrode assembly, and the cover has an electrode lead-out hole. An electrode terminal is mounted in the electrode lead-out hole. The electrode terminal includes a terminal body, which includes a columnar portion, a first limiting portion, and a second limiting portion. At least a portion of the columnar portion is located within the electrode lead-out hole. A first recess is provided in the columnar portion. The first limiting portion and the second limiting portion are both connected to and protrude from the outer wall of the columnar portion. The first limiting portion and the second limiting portion are respectively provided on the outer and inner sides of the cover and are used to clamp a portion of the cover.

[0058] In the above technical solution, the first limiting part and the second limiting part clamp a portion of the cover from both sides to fix the terminal body to the cover.

[0059] In some embodiments, the terminal body has a second outer surface, and a first recess extends from the second outer surface toward the first outer surface of the connector in a direction facing the electrode assembly.

[0060] In some embodiments, the electrode terminal further includes a sealing plate, which is connected to the terminal body and closes the opening of the first recess.

[0061] In the above technical solution, the sealing plate can protect the connection part from the outside, reduce the external impurities entering the first recess, reduce the risk of the connection part being damaged by external impurities, and improve the sealing performance of the battery cell.

[0062] In some embodiments, the electrode assembly further includes a second electrode tab with a polarity opposite to that of the first electrode tab, the second electrode tab being disposed around the central axis of the electrode assembly. The first electrode tab is disposed at the end of the electrode assembly facing the electrode terminal, and the second electrode tab is disposed at the end of the electrode assembly away from the electrode terminal, the second electrode tab being electrically connected to the housing.

[0063] In the above technical solution, the housing itself can serve as one of the output electrodes of a battery cell, thereby eliminating a traditional electrode terminal and simplifying the structure of the battery cell. When multiple battery cells are assembled into a group, the housing can be electrically connected to the busbar component, which increases the current-carrying area and allows for more flexible structural design of the busbar component.

[0064] In some embodiments, the second tab is a negative tab, and the base material of the housing is steel. The steel housing is less susceptible to corrosion by the electrolyte at low potentials.

[0065] In some embodiments, the housing has an opening at the end opposite to the electrode terminals, and the battery cell also includes a cover for closing the opening.

[0066] Secondly, embodiments of this application provide a battery comprising a plurality of battery cells according to any of the embodiments of the first aspect.

[0067] Thirdly, embodiments of this application provide an electrical device including a battery as described in the second aspect, the battery being used to provide electrical energy. Attached Figure Description

[0068] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0069] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0070] Figure 2 Explosion diagrams of batteries provided for some embodiments of this application;

[0071] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0072] Figure 4 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application;

[0073] Figure 5 A cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0074] Figure 6 for Figure 5 A partially enlarged schematic diagram of a single battery cell;

[0075] Figure 7 for Figure 6 Enlarged view at box B;

[0076] Figure 8 for Figure 7 Enlarged view at point C in the circle;

[0077] Figure 9 A schematic diagram of the terminal body of the electrode terminal of a battery cell provided in some embodiments of this application;

[0078] Figure 10 A schematic diagram of the terminal body of the electrode terminal of a battery cell provided in some embodiments of this application;

[0079] Figure 11 This is a schematic diagram of the electrode assembly and current collector of a battery cell according to some embodiments of this application;

[0080] Figure 12 This is a schematic diagram of the electrode assembly and current collector of a battery cell according to other embodiments of this application;

[0081] Figure 13 Partial cross-sectional schematic diagram of a battery cell provided for other embodiments of this application;

[0082] Figure 14 for Figure 13 Enlarged view at box E;

[0083] Figure 15 An exploded view of the electrode terminals of a battery cell provided in some embodiments of this application;

[0084] Figure 16 This is a top view schematic diagram of the electrode terminals of a battery cell provided in some embodiments of this application;

[0085] Figure 17 Partial cross-sectional schematic diagram of a battery cell provided for other embodiments of this application;

[0086] Figure 18 A partial cross-sectional schematic diagram of a battery cell provided for some embodiments of this application;

[0087] Figure 19 This is a cross-sectional schematic diagram of a battery cell provided for other embodiments of this application.

[0088] The accompanying drawings are not drawn to scale. Detailed Implementation

[0089] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0090] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0091] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0092] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0093] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0094] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0095] In this application, "multiple" means two or more (including two).

[0096] In this application, the term "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; similarly, "perpendicular" includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering.

[0097] In this application, the battery cell may include lithium-ion secondary battery cell, lithium-ion primary battery cell, lithium-sulfur battery cell, sodium lithium-ion battery cell, sodium-ion battery cell, or magnesium-ion battery cell, etc., and the embodiments of this application are not limited thereto.

[0098] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. A battery generally includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0099] A battery cell includes electrode components and an electrolyte. The electrode components include a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrode components. The positive electrode includes a positive current collector and a positive active material layer, with the active material layer coated on the surface of the current collector. The current collector includes a positive current-collecting section and a positive electrode tab; the current-collecting section is coated with the positive active material layer, while the positive electrode tab is not. Taking a lithium-ion battery as an example, the positive current collector can be made of aluminum, and the positive active material layer includes the positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer, with the active material layer coated on the surface of the current collector. The current collector includes a negative current-collecting section and a negative electrode tab; the current-collecting section is coated with the negative active material layer, while the negative electrode tab is not. The negative electrode current collector can be made of copper, and the negative electrode active material layer includes the negative electrode active material, which can be carbon or silicon, etc. The separator can be made of PP (polypropylene) or PE (polyethylene), etc.

[0100] The battery cell also includes a housing for accommodating the electrode assembly and electrode terminals disposed on the housing. The electrode terminals are used for electrical connection to the electrode assembly to enable charging and discharging of the electrode assembly. To facilitate assembly and ensure the overcurrent capacity of the battery cell, the battery cell is typically connected to the tabs and electrode terminals of the electrode assembly via current collectors.

[0101] To reduce resistance and improve current carrying capacity, the inventors typically use welding to connect the electrode terminals and the current collector. The inventors noticed that if the current collector and electrode terminals are welded first, and then the electrode terminals are installed into the housing, metal particles generated during welding may adhere to the electrode terminals or the current collector and fall into the housing during assembly. These metal particles falling into the housing may puncture the insulating components of the electrode assembly, posing a short-circuit risk.

[0102] To reduce the number of metal particles falling into the housing, the inventors attempted to first install the electrode terminals onto the housing, and then weld the current collector and electrode terminals from the outside of the electrode terminals. In this way, the housing can block metal particles and reduce the number of metal particles entering the housing.

[0103] However, the inventors discovered during the welding process that when welding the electrode terminals and current collectors from the outside of the electrode terminals, the electrode terminals need to be melted through. Since the electrode terminals usually have a large thickness, this results in high welding power and high heat generation. The heat is conducted to other components, such as seals and electrode assemblies, which can easily damage these components and cause safety hazards.

[0104] In view of this, the present application provides a technical solution that reduces the thickness of the portion of the electrode terminal used for welding with the current collector by providing a recess on the electrode terminal, thereby reducing welding difficulty, reducing welding heat generation, and improving safety.

[0105] The technical solutions described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0106] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0107] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0108] Figure 1 The diagram shows the structural features of a vehicle as provided in some embodiments of this application. Figure 1As shown, a battery 2 is installed inside the vehicle 1. The battery 2 can be located at the bottom, front, or rear of the vehicle 1. The battery 2 can be used to power the vehicle 1; for example, the battery 2 can serve as the operating power source for the vehicle 1.

[0109] Vehicle 1 may also include controller 3 and motor 4. Controller 3 is used to control battery 2 to supply power to motor 4, for example, for the power needs of vehicle 1 during start-up, navigation and driving.

[0110] In some embodiments of this application, the battery 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0111] Figure 2 This is a schematic diagram of a battery explosion provided for some embodiments of this application. For example... Figure 2 As shown, battery 2 includes a housing 5 and battery cells ( Figure 2 (Not shown), the battery cells are housed inside the casing 5.

[0112] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0113] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0114] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0115] In battery 2, there can be one or more individual battery cells. If there are multiple individual battery cells, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple individual battery cells are connected in both series and parallel configurations. Multiple individual battery cells can be directly connected in series, parallel, or in a mixed configuration and then housed within housing 5. Alternatively, multiple individual battery cells can first be connected in series, parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, parallel, or in a mixed configuration to form a whole and housed within housing 5.

[0116] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0117] In some embodiments, such as Figure 3 As shown, there are multiple battery cells 7, which are first connected in series, parallel, or a combination of both to form a battery module 6. These battery modules 6 are then connected in series, parallel, or a combination of both to form a whole, which is housed within the casing.

[0118] Multiple battery cells 7 in battery module 6 can be electrically connected through busbar components 8 to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6. There can be one or more busbar components, and each busbar component 8 is used to electrically connect at least two battery cells.

[0119] Figure 4 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application; Figure 5 A cross-sectional schematic diagram of a battery cell provided in some embodiments of this application; Figure 6 for Figure 5 A partially enlarged schematic diagram of a single battery cell; Figure 7 for Figure 6 Enlarged view at box B; Figure 8 for Figure 7 Enlarged view of point C in the circle.

[0120] like Figures 4 to 8 As shown, in some embodiments of this application, the battery cell 7 includes an electrode assembly 10, a housing 20, electrode terminals 30, and a current collector 40. The electrode assembly 10 includes a first tab 11. The housing 20 is used to house the electrode assembly 10. The electrode terminals 30 are disposed in the housing 20, and the electrode terminals 30 include a first recess 31 and a connecting portion 32 located at the bottom of the first recess 31. The current collector 40 is connected to the first tab 11 and welded to the connecting portion 32.

[0121] The electrode assembly 10 includes a first electrode and a second electrode with opposite polarities. One of the first electrode and the second electrode is a positive electrode, and the other is a negative electrode. Exemplarily, the electrode assembly 10 generates electrical energy through oxidation and reduction reactions during the insertion / extraction of ions in the positive and negative electrode plates. Optionally, the electrode assembly 10 further includes a separator for insulating and isolating the first electrode and the second electrode.

[0122] In some examples, the first electrode, the second electrode, and the spacer are all strip structures, wound together around the central axis A to form a wound structure. The wound structure can be cylindrical, flat, or other shapes. In other examples, the electrode assembly 10 can also be a stacked structure formed by arranging the first electrode, the spacer, and the second electrode in layers.

[0123] The first tab 11 can be the portion of the first electrode sheet that is not coated with the active material layer. The first tab 11 can be a positive tab or a negative tab.

[0124] The housing 20 is a hollow structure, forming an interior space for accommodating the electrode assembly 10. The housing 20 can have various shapes and sizes, such as cuboid, cylindrical, or hexagonal prism. The shape of the housing 20 can be determined based on the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is cylindrical, a cylindrical housing can be used; if the electrode assembly 10 is cuboid, a cuboid housing can be used. Optionally, both the electrode assembly 10 and the housing 20 can be cylindrical.

[0125] The shell 20 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc. This application embodiment does not impose any special restrictions on this.

[0126] The casing 20 can be positively charged, negatively charged, or uncharged.

[0127] The electrode terminal 30 can serve as the output electrode of the battery cell 7, which can electrically connect the battery cell 7 to an external circuit to enable charging and discharging of the battery cell 7. Optionally, the electrode terminal 30 is used to connect to a busbar component to enable electrical connection between the battery cells 7.

[0128] The electrode terminal 30 can be disposed insulatedly on the housing 20 or electrically connected to the housing 20. This application embodiment does not limit this, as long as the positive electrode and the negative electrode are prevented from conducting.

[0129] The first recess 31 can be recessed from the side of the electrode terminal 30 away from the electrode assembly 10 in the direction facing the electrode assembly 10, or it can be recessed from the side of the electrode terminal 30 facing the electrode assembly 10 in the direction away from the electrode assembly 10.

[0130] The connecting portion 32 is the part of the electrode terminal 30 that corresponds to the bottom surface of the first recess 31.

[0131] The current collector 40 electrically connects the first tab 11 to the electrode terminal 30. The embodiments of this application do not limit the connection method between the first tab 11 and the current collector 40. For example, the current collector 40 can be connected to the first tab 11 by welding, abutting or bonding.

[0132] The current collector 40 and the connecting portion 32 are connected by welding. For example, the current collector 40 and the connecting portion 32 are connected by laser welding.

[0133] In this embodiment of the application, by opening a first recess 31 on the electrode terminal 30 to reduce the thickness of the connecting portion 32, the welding power required for welding the connecting portion 32 and the current collector 40 is reduced, heat generation is reduced, the risk of other components being burned is reduced, and safety is improved.

[0134] In some embodiments, the electrode assembly 10 includes a main body 12, a first tab 11, and a second tab 13, the first tab 11 and the second tab 13 protruding from the main body 12. The first tab 11 is the portion of the first electrode sheet that is not coated with an active material layer, and the second tab 13 is the portion of the second electrode sheet that is not coated with an active material layer.

[0135] The first tab 11 and the second tab 13 can extend from the same side of the main body 12, or they can extend from opposite sides respectively. For example, the first tab 11 is located at the end of the electrode assembly 10 facing the electrode terminal 30, and the second tab 13 is located at the end of the electrode assembly 10 away from the electrode terminal 30.

[0136] In some embodiments, the first tab 11 is wound multiple times around the central axis A of the electrode assembly 10; in other words, the first tab 11 includes multiple tab layers. After winding, the first tab 11 is generally cylindrical, with gaps between adjacent tab layers. Embodiments of this application can process the first tab 11 to reduce the gaps between tab layers, facilitating the connection of the first tab 11 to the current collector 40. For example, embodiments of this application can flatten the first tab 11 so that the end regions of the first tab 11 away from the main body 12 are gathered together; the flattening process forms a dense end face at the end of the first tab 11 away from the main body 12, reducing the gaps between tab layers and facilitating the connection of the first tab 11 to the current collector 40. Alternatively, embodiments of this application can also fill the gaps between adjacent tab layers with conductive material to reduce the gaps between tab layers.

[0137] In some embodiments, the second tab 13 is wound around the central axis A of the electrode assembly 10 multiple times, and the second tab 13 includes multiple tab layers. Exemplarily, the second tab 13 is also flattened to reduce the gaps between the tab layers of the second tab 13.

[0138] The central axis A of the electrode assembly 10 is a virtual straight line. The first electrode, the second electrode, and the separator can be wound with the central axis A as a reference.

[0139] In some embodiments, the housing 20 includes a cylindrical body 21 and a cover 22 connected to the cylindrical body 21. The cylindrical body 21 is disposed around the outer periphery of the electrode assembly 10, and the cover 22 is provided with an electrode lead-out hole 221, and the electrode terminal 30 is installed in the electrode lead-out hole 221.

[0140] The cover 22 and the cylinder 21 can be an integrally formed structure, that is, the shell 20 is a one-piece component. Of course, the cover 22 and the cylinder 21 can also be two separate components, which are then connected together by welding, riveting, bonding or other methods.

[0141] Electrode lead-out hole 221 penetrates the cover 22 to facilitate the lead-out of electrical energy in electrode assembly 10 to the outside of housing 20.

[0142] The central axis A is a virtual straight line that passes through the electrode lead-out hole 221. The central axis A of the electrode assembly 10 may or may not coincide with the axis of the electrode lead-out hole 221.

[0143] Electrode terminal 30 is used to mate with electrode lead-out hole 221 to cover electrode lead-out hole 221. Electrode terminal 30 may or may not extend into electrode lead-out hole 221. Electrode terminal 30 is fixed to cover 22. Electrode terminal 30 may be fixed as a whole to the outside of cover 22, or it may extend into the inside of housing 20 through electrode lead-out hole 221.

[0144] In some embodiments, the cover 22 and the cylinder 21 are integrally formed. This eliminates the need for the connection process between the cover 22 and the cylinder 21.

[0145] When the cover 22 and the cylinder 21 are electrically connected to the positive or negative terminal of the electrode assembly 10, the resistance at the connection between the cover 22 and the cylinder 21 is small due to the integral structure of the connection, thereby improving the current carrying capacity. The cover 22 can be used to connect to external components (such as busbar components). When the battery cell is subjected to external impact, the external component may pull on the cover 22, causing the connection between the cover 22 and the cylinder 21 to be subjected to force. The above technical solution integrates the cover 22 and the cylinder 21, thereby improving the strength of the connection between the cover 22 and the cylinder 21 and reducing the risk of connection failure.

[0146] In some embodiments, the housing 20 may be formed by a stretching process.

[0147] In some embodiments, the housing 20 has an opening 211 at one end away from the electrode terminal 30, and the battery cell 7 also includes a cover plate 50 for closing the opening 211.

[0148] Specifically, the cylinder 21 has an opening at the end opposite to the cover 22, and the cover plate 50 closes onto the opening of the cylinder 21 to seal the opening. The cover plate 50 can have various structures, such as a plate-like structure.

[0149] In some embodiments, the cover plate 50 may be a circular cover plate, a rectangular cover plate, a square cover plate, a hexagonal cover plate, or a cover plate of other shapes.

[0150] In some embodiments, the cover plate 50 is welded to the cylinder 21.

[0151] In some embodiments, the cover 22 is circular, and the electrode assembly 10 is cylindrical; the central axis A coincides with the axis of the electrode lead-out hole 221. This embodiment does not require the central axis A to be completely coincident with the axis of the electrode lead-out hole 221; a process-permissible deviation may exist between them.

[0152] In this embodiment, the electrode lead-out hole 221 is generally located in the middle of the cover 22, and correspondingly, the electrode terminal 30 is also installed in the middle of the cover 22. When multiple battery cells 7 are assembled into a group, the positioning accuracy requirements of the electrode terminal 30 can be reduced, and the assembly process can be simplified.

[0153] For example, the axis of the electrode lead-out hole 221 coincides with the axis of the cover 22, and the cover 22 is an annular structure arranged around the axis of the electrode lead-out hole 221.

[0154] For example, the axis of the electrode terminal 30 coincides with the axis of the electrode lead-out hole 221.

[0155] In other embodiments, the cover 22 may also be rectangular, and the electrode assembly 10 may be flat. The electrode lead-out hole 221 may be located near the end of the cover 22 along its length.

[0156] In some embodiments, the electrode assembly 10 further includes a second electrode 13 with the opposite polarity to the first electrode 11, and the second electrode 13 is disposed around the central axis A of the electrode assembly 10. The first electrode 11 is disposed at the end of the electrode assembly 10 facing the electrode terminal 30, and the second electrode 13 is disposed at the end of the electrode assembly 10 away from the electrode terminal 30. The second electrode 13 is electrically connected to the housing 20.

[0157] The housing 20 itself can serve as an output electrode of one of the battery cells 7, thus eliminating a traditional electrode terminal and simplifying the structure of the battery cell 7. When multiple battery cells 7 are assembled into a group, the housing 20 can be electrically connected to the busbar component, which can increase the current flow area and make the structural design of the busbar component more flexible.

[0158] In some embodiments, the second tab 13 is the negative tab, and the base material of the housing 20 is steel. The housing 20 is electrically connected to the negative tab, meaning the housing 20 is in a low potential state. The steel housing 20 is less susceptible to corrosion by the electrolyte in a low potential state.

[0159] In some embodiments, the cylinder 21 is used to connect the second tab 13 and the cover 22 so that the second tab 13 and the cover 22 are electrically connected.

[0160] The cylinder 21 can be directly electrically connected to the second electrode 13, or it can be electrically connected to the second electrode 13 through other components. For example, the second electrode 13 is electrically connected to the cylinder 21 through the cover plate 50.

[0161] The cover 22 and the electrode terminal 30 have different polarities. In this case, one of the cover 22 and the electrode terminal 30 can serve as the positive output terminal of the battery cell 7, and the other can serve as the negative output terminal of the battery cell 7. In this embodiment, the positive and negative output terminals are located on the same side of the battery cell 7, which simplifies the connection process between multiple battery cells 7.

[0162] The electrode lead-out hole 221 in this embodiment is formed after the housing 20 is stretched and formed.

[0163] The inventors attempted to roll-press the open end of the cylinder to fold it inward and form a flange structure, which then pressed against the cover plate to secure it. The inventors then mounted electrode terminals onto the cover plate, using the flange structure and electrode terminals as the two output poles of the battery cell. However, the larger the flange structure, the higher the risk of curling and wrinkling after molding. If curling and wrinkling occur, the surface of the flange structure will be uneven, leading to poor welding when it is welded to external busbar components. Therefore, the size of the flange structure is relatively limited, resulting in insufficient current carrying capacity of the battery cell.

[0164] In this embodiment, an electrode lead-out hole 221 for mounting the electrode terminal 30 is formed on the cover 22 using an opening process, so that the positive and negative output terminals are located at the end of the battery cell 7 away from the opening of the cylinder 21. The cover 22 is formed during the molding process of the shell 20, and the opening of the electrode lead-out hole 221 can also ensure flatness and ensure the connection strength between the cover 22 and the busbar component. At the same time, the flatness of the cover 22 is not constrained by its own size, so the cover 22 can have a larger size, thereby improving the current carrying capacity of the battery cell 7.

[0165] In some embodiments, the current collector 40 is welded to the connection portion 32 to form a first weld portion W1. In the thickness direction X of the connection portion 32, the first weld portion W1 extends from the side of the connection portion 32 away from the current collector 40 into the interior of the current collector 40.

[0166] During welding, a portion of the connecting portion 32 and a portion of the current collector 40 melt to form a molten pool, which solidifies to form a first weld portion W1. Exemplarily, when the electrode assembly 10 and the current collector 40 are installed into the housing 20, and the current collector 40 is pressed against the connecting portion 32, an external welding device can weld the connecting portion 32 and the current collector 40 from the side of the connecting portion 32 opposite to the current collector 40 to form the first weld portion W1. The first weld portion W1 is exposed on the surface of the connecting portion 32 opposite to the current collector 40.

[0167] The embodiments of this application do not impose special limitations on the shape, position, depth, or number of the first welding portion W1. For example, the shape of the first welding portion W1 can be straight, rectangular, annular, spiral, V-shaped, or other shapes. There can be one or more first welding portions W1.

[0168] The first welded portion W1 may penetrate the current collecting member 40. For example, the first welded portion W1 may penetrate the current collecting member 40 and the connecting portion 32, and the first welded portion W1 may be exposed on the surface of the current collecting member 40 away from the connecting portion 32. Of course, the first welded portion W1 may also not penetrate the current collecting member 40, that is, the first welded portion W1 may not be exposed on the surface of the current collecting member 40 away from the connecting portion 32.

[0169] The first welding part W1 extends from the connecting part 32 into the interior of the current collector 40 to connect the current collector 40 and the connecting part 32, thereby reducing the contact resistance between the current collector 40 and the electrode terminal 30 and improving the current carrying capacity.

[0170] In some embodiments, in the thickness direction X of the connecting portion 32, the first weld portion W1 does not extend beyond the surface of the current collector 40 away from the connecting portion 32.

[0171] The first welded part W1 is spaced at a predetermined distance from the surface of the current collector 40 away from the connecting part 32, so as to avoid the current collector 40 being melted through, reduce the risk of metal particles being generated on the surface of the current collector 40 away from the connecting part 32, and improve safety.

[0172] In some embodiments, the housing 20 includes a cylindrical body 21 and a cover 22 connected to the cylindrical body 21. The cylindrical body 21 is disposed around the outer periphery of the electrode assembly 10, and the cover 22 is provided with an electrode lead-out hole 221, into which the electrode terminal 30 is mounted. Both the first welding part W1 and the cover 22 are annular. The outer diameter of the cover 22 is D0, and the inner diameter of the first welding part W1 is D1. D1 and D0 satisfy: 0.1≤D1 / D0≤0.6.

[0173] The first welded part W1 can be a closed structure or an open structure. In other words, the first welded part W1 can be a semi-circular ring or a full circular ring.

[0174] D0 is positively correlated with the diameter of the electrode assembly 10. The larger D0 is, the higher the capacity of the electrode assembly 10, and the higher the requirement for the current-carrying area of ​​the first welding part W1 in the battery cell 7. The smaller D1 is, the smaller the perimeter of the first welding part W1, and the smaller the current-carrying area of ​​the first welding part W1. If D1 / D0 is too small, then due to the large D0 and small D1, the current-carrying area of ​​the first welding part W1 will be insufficient, and the first welding part W1 will generate more heat during charging and discharging, making it difficult to meet the requirements of the battery cell 7 for current-carrying capacity and temperature rise during fast charging. After in-depth research and a large number of experiments, the inventors found that when D1 / D0 ≥ 0.1, the requirements of the battery cell 7 for current-carrying capacity and temperature rise can be met.

[0175] The larger D1 is, the larger the size of the electrode lead-out hole 221 and the smaller the area of ​​the cover 22. Similarly, the smaller D0 is, the smaller the area of ​​the cover 22. If D1 / D0 is too large, the cover 22 will be prone to deformation when the battery cell 7 vibrates due to the small D0 and large D1, causing safety hazards. The cover 22 can serve as an output terminal of the battery cell 7 to connect with the busbar component. If D1 / D0 is too large, the connection area between the cover 22 and the busbar component will be too small, resulting in insufficient current flow area and high heat generation at the connection point, making it difficult to meet the requirements of the battery cell 7 for current flow capacity and temperature rise during fast charging. After in-depth research and extensive experiments, the inventors found that when D1 / D0 ≤ 0.6, the requirements of the battery cell 7 for current flow capacity and temperature rise can be met, improving the safety of the battery cell 7.

[0176] D1 / D0 can be 0.1, 0.2, 0.3, 0.4, 0.5 or 0.6.

[0177] In some embodiments, after in-depth research and extensive experimentation, the inventors discovered that when 0.2 ≤ D1 / D0 ≤ 0.4, the requirements of the battery cell 7 for overcurrent capacity and temperature rise can be better met, thereby improving the safety of the battery cell 7.

[0178] In some embodiments, D1 is 5mm-14mm.

[0179] If D1 is too small, the current-carrying area of ​​the first welded part W1 will be insufficient, resulting in excessive heat generation at the first welded part W1 during charging and discharging, which will be difficult to meet the requirements of the battery cell 7 for current carrying capacity and temperature rise during fast charging. If D1 is too large, the current-carrying area between the cover 22 and the current-carrying component will be insufficient, resulting in excessive heat generation at the connection between the cover 22 and the current-carrying component. After in-depth research and extensive experiments, the inventors discovered that limiting D1 to 5mm-14mm can meet the requirements of the battery cell 7 for current carrying capacity and temperature rise.

[0180] Optionally, D1 can be 5mm, 7mm, 9mm, 10mm, 12mm or 14mm.

[0181] In some embodiments, the dimension of the first welding portion W1 in the thickness direction X of the connecting portion 32 is h, and the thickness of the area of ​​the connecting portion 32 for welding with the current collecting member 40 is d0. d0 and h satisfy: 1 ​​< h / d0 ≤ 1.5.

[0182] The first welded part W1 is annular. Due to process errors, different areas of the first welded part W1 may have different weld depths in the thickness direction X. h can be the dimension along the thickness direction X of the area with the smallest weld depth in the first welded part W1.

[0183] In some examples, the connecting portion 32 is a flat plate structure with uniform thickness, and any part of the connecting portion 32 can be used for welding with the current collecting member 40, where d0 is the thickness of the connecting portion 32. In other examples, the connecting portion 32 has a non-uniform thickness structure, and the area of ​​the connecting portion 32 with a smaller thickness can be the area of ​​the connecting portion 32 used for welding with the current collecting member 40. This can reduce the power required for welding and reduce heat generation; for example, the connecting portion 32 can reduce the local thickness by forming a groove, and the area of ​​the connecting portion 32 corresponding to the groove can be used as the area of ​​the connecting portion 32 used for welding with the current collecting member 40.

[0184] If h / d0 ≤ 1, the penetration depth of the first welded part W1 is small, and the first welded part W1 is formed entirely on the connecting part 32, resulting in a weak weld. The first welded part W1 cannot effectively connect the current collector 40 and the connecting part 32. When d0 is constant, the larger h is, the greater the power required for welding and the higher the heat generated during the welding process. If h is too large, the high temperature generated during welding can easily damage components around the electrode terminal 30, causing safety hazards.

[0185] After in-depth research and a large number of experiments, the inventors discovered that when 1 < h / d0 ≤ 1.5, welding heat generation can be reduced and welding difficulty can be lowered while ensuring the connection between the current collector 40 and the connecting part 32.

[0186] Optionally, h / d0 can be 1.05, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0187] In some embodiments, the thickness of the area of ​​the current collector 40 for welding with the connection portion 32 is d1, d0 and d1 satisfy: 0.5≤d1 / d0≤1.2.

[0188] The area of ​​the manifold 40 used for welding with the connecting part 32 refers to the area of ​​the manifold 40 that abuts against the connecting part 32.

[0189] When d0 is constant, the smaller d1 is, the easier it is for the current collector 40 to be melted through during the welding process, and the easier it is for the high-temperature particles generated during welding to fall into the battery cell 7; the larger d1 is, the larger the space and weight occupied by the current collector 40, and the lower the energy density of the battery cell 7.

[0190] After in-depth research and a large number of experiments, the inventors discovered that when 0.5≤d1 / d0≤1.2, the risk of the current collector 40 being melted through can be reduced, and the energy density loss of the battery cell 7 can be reduced.

[0191] Optionally, d1 / d0 can be 0.5, 0.7, 0.9, 1.0 or 1.2.

[0192] In some embodiments, d0 is 0.4mm-1.2mm.

[0193] The smaller d0 is, the lower the current carrying capacity of the connection part 32. If d0 is too small, the connection part 32 may not be able to meet the requirements of the battery cell 7 for current carrying capacity and temperature rise during fast charging. The larger d0 is, the greater the power required for welding and the higher the heat generated during the welding process. If d0 is too large, the high temperature generated during welding can easily damage the components around the electrode terminal 30, causing safety hazards.

[0194] After in-depth research and extensive experiments, the inventors discovered that limiting d0 to 0.4mm-1.2mm can meet the requirements of the battery cell 7 for overcurrent capacity and temperature rise, while reducing welding heat generation and improving safety.

[0195] Optionally, d0 can be 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1.0mm or 1.2mm.

[0196] Optionally, after in-depth research and extensive experimentation, the inventors discovered that limiting d0 to 0.6mm-1.0mm better meets the requirements of the battery cell 7 for current carrying capacity and temperature rise, while reducing welding heat generation and improving safety.

[0197] In some embodiments, d1 is 0.2mm-0.6mm. Optionally, d1 is 0.3mm-0.5mm.

[0198] In some embodiments, at least a portion of the first tab 11 is located on the side of the current collector 40 opposite to the electrode terminal 30 and is supported on the current collector 40.

[0199] The first tab 11 can support the current collector 40 so that the current collector 40 fits against the connecting part 32. When the battery cell 7 vibrates, the first tab 11 can restrict the movement of the current collector 40 relative to the connecting part 32, thereby reducing the force on the first welded part W1 and reducing the risk of tearing of the first welded part W1.

[0200] During the assembly of the battery cell 7, the current collector 40 can be supported by the first tab 11, so that the current collector 40 and the connecting part 32 are tightly fitted, reducing the relative displacement of the current collector 40 and the connecting part 32 during the welding process and reducing the risk of poor welding.

[0201] In some embodiments, the first portion 111 of the first tab 11 is located on the side of the connecting portion 32 away from the first recess 31 and is used to support the portion of the current collecting member 40 opposite to the connecting portion 32.

[0202] In the thickness direction X of the connecting portion 32, the first portion 111 is disposed opposite to the connecting portion 32. In other words, the first portion 111 is the part of the first tab 11 that overlaps with the connecting portion 32 in the thickness direction X.

[0203] The first part 111 can support the portion of the current collector 40 opposite to the connecting part 32, so that the current collector 40 and the connecting part 32 fit tightly together, reducing the risk of incomplete welding. During the welding process, the first part 111 can also limit the deformation of the current collector 40 and improve the morphology of the current collector 40.

[0204] In some embodiments, the second portion 112 of the first tab 11 surrounds the outer periphery of the first portion 111 and is used to support the area of ​​the current collector 40 that is not opposite to the connecting portion 32.

[0205] The second part 112 is the portion of the first tab 11 that does not overlap with the connecting portion 32 in the thickness direction X. For example, the second part 112 is a ring structure.

[0206] By providing the second part 112, the area of ​​the region supporting the current collecting member 40 of the first electrode tab 11 can be increased, improving the supporting effect of the first electrode tab 11, reducing the pressure between the first electrode tab 11 and the current collecting member 40, and lowering the risk of the first electrode tab 11 being crushed. When welding the connection part 32 and the current collecting member 40, the second part 112 can support the current collecting member 40, thereby reducing the relative displacement between the current collecting member 40 and the connection part 32 during the welding process and lowering the risk of incomplete welding.

[0207] In some embodiments, the first tab 11 may not be entirely opposite to the connecting portion 32 in the thickness direction X. In other words, the first tab 11 may only include the second portion 112.

[0208] In some embodiments, the second portion 112 is welded to the current collector 40 to form a third welded portion W3.

[0209] When assembling the battery cell 7, the second part 112 of the first tab 11 of the electrode assembly 10 can be welded to the current collector 40 first, and then the electrode assembly 10 and the current collector 40 can be placed into the housing 20. Specifically, when welding the second part 112 and the current collector 40, the current collector 40 can be pressed against the flattened end face of the first tab 11 first, and then an external welding device emits a laser on the surface of the current collector 40 away from the first tab 11, and the laser welds the current collector 40 and the second part 112 of the first tab 11 together.

[0210] The shape of the third welding part W3 can be straight, C-shaped, ring-shaped, spiral, V-shaped, or other shapes, and this embodiment does not limit this. There can be one or more third welding parts W3.

[0211] The third welded part W3 can reduce the contact resistance between the current collector 40 and the second part 112, thereby improving the current carrying capacity.

[0212] In some embodiments, the current collector 40 has a protrusion 41 on the side facing the first electrode tab 11, and the protrusion 41 is welded to the second portion 112 to form a third weld portion W3.

[0213] When assembling the current collector 40 and the electrode assembly 10, the protrusion 41 of the current collector 40 is first pressed against the second part 112, and then the protrusion 41 and the second part 112 are welded. The protrusion 41 can fit better with the second part 112, reducing the risk of poor welding.

[0214] In some embodiments, the protrusion 41 can press the second portion 112 and be embedded into the second portion 112.

[0215] In some embodiments, apart from the protrusion 41, the other parts of the current collecting member 40 are generally flat plate structures.

[0216] In some embodiments, the current collector 40 forms a second recess 42 at a position corresponding to the protrusion 41. The second recess 42 is recessed relative to the surface of the current collector 40 facing away from the first electrode tab 11 in a direction facing the first electrode tab 11. A transition portion is formed between the bottom surface of the second recess 42 and the top surface of the protrusion 41. The transition portion is welded to the second portion 112 to form a third weld portion W3. By providing the second recess 42, the thickness of the transition portion can be reduced, thereby reducing the welding power required to weld the transition portion to the second portion 112, reducing heat generation, and lowering the risk of the electrode assembly 10 being burned.

[0217] The third welded part W3 is formed by welding, and its surface is uneven. In this embodiment, by providing the second recess 42, the surface of the third welded part W3 can be recessed relative to the surface of the current collector 40 away from the surface of the first electrode tab 11, so as to avoid the third welded part W3 from other components (such as electrode terminals 30).

[0218] In some embodiments, a retaining piece (not shown) may be provided in the second recess 42. The retaining piece is used to cover the third welded portion W3 to fix residual metal particles on the third welded portion W3, reducing the risk of metal particles falling into the electrode assembly 10 and causing a short circuit. The retaining piece may be an insulating patch, an insulating adhesive layer, or other structures.

[0219] Figure 9 This is a schematic diagram of the terminal body of the electrode terminal of a battery cell provided in some embodiments of this application.

[0220] like Figure 9 As shown, in some embodiments, the first welding part W1 is a non-closed structure, and the central angle α of the first welding part W1 is 180°-330°.

[0221] α is positively correlated with the current-carrying area of ​​the first welded portion W1. The smaller α is, the smaller the current-carrying area of ​​the first welded portion W1, and the higher the heat generated when current flows through the first welded portion W1. In the embodiments of this application, α is limited to 180°-330° so that the first welded portion meets the requirements of the battery cell for current carrying capacity and temperature rise.

[0222] The first welded part W1 is a non-closed structure. The unwelded area between the two ends of the first welded part W1 along the circumferential direction can release welding stress and reduce stress concentration.

[0223] Figure 10 This is a schematic diagram of the terminal body of the electrode terminal of a battery cell provided in some embodiments of this application.

[0224] like Figure 10As shown, in some embodiments, the first weld portion W1 is a closed structure. In other words, the central angle of the first weld portion W1 is 360°. Embodiments of this application can increase the welding area and improve the welding strength and flow capacity of the first weld portion.

[0225] Figure 11 This is a schematic diagram of the electrode assembly and current collector of a battery cell according to some embodiments of this application.

[0226] Please refer to the above as well. Figures 6 to 11 In some embodiments, the first tab 11 is disposed around the central axis A of the electrode assembly 10, and the cross section of the first tab 11 perpendicular to the central axis A is annular. The outer radius of the first tab 11 is R, and the minimum distance between the third welding part W3 and the central axis A in the radial direction of the first tab 11 is D2, both satisfying: 0.2≤D2 / R≤0.8.

[0227] The cross section of the first tab 11 perpendicular to the central axis A is not required to be an absolute circle; a certain deviation is allowed.

[0228] R is positively correlated with the diameter of the electrode assembly 10. The larger R is, the greater the current generated by the electrode assembly 10, and the higher the requirement for the current-carrying area of ​​the battery cell 7. The portion of the current collector 40 near the central axis A can be used for welding with the connection part 32. The smaller D2 is, the smaller the area of ​​the current collector 40 that can be welded with the connection part 32, and the smaller the current-carrying area between the current collector 40 and the connection part 32. If D2 / R is too small, then due to the small D2 and large R, the current-carrying area between the current collector 40 and the connection part 32 will be insufficient. The weld between the current collector 40 and the connection part 32 will generate a large amount of heat during charging and discharging, making it difficult to meet the requirements of the battery cell 7 for current carrying capacity and temperature rise during fast charging.

[0229] The first tab 11 comprises multiple tab layers, each tab layer revolving around the central axis A. In the radial direction of the first tab 11, the multiple tab layers are stacked along the radial direction of the first tab 11. Current on the tab layer directly connected to the third weld portion W3 can be directly conducted to the current collector 40 through the third weld portion W3; however, current on the tab layer not connected to the third weld portion W3 needs to be conducted to the tab layer directly connected to the third weld portion W3 before it can be conducted to the current collector 40 through the third weld portion W3. This results in differences in the conductive paths between the multiple tab layers and the first wall. If the difference is too large, polarization problems can easily occur.

[0230] If D2 / R is too small, the distance between the third welding part W3 and the outermost tab layer will be too large, resulting in a large difference between the current path between the outermost tab layer and the electrode terminal 30 and the current path between the innermost tab layer and the electrode terminal 30. This will cause uneven current density in the first electrode of the electrode assembly 10 and increase internal resistance.

[0231] After in-depth research and extensive experiments, the inventors discovered that when D2 / R≥0.2, the requirements for overcurrent capacity and temperature rise of the battery cell 7 can be met.

[0232] The larger D2 is, the further out the tab layer is directly connected to the third welding part W3. If D2 is too large, it will result in fewer tab layers connected to the third welding part W3, and the distance between the third welding part W3 and the innermost tab layer will be too large. This will cause a large difference between the current path between the outermost tab layer and the electrode terminal 30 and the current path between the innermost tab layer and the electrode terminal 30, resulting in uneven current density of the first electrode and increased internal resistance.

[0233] After in-depth research and a large number of experiments, the inventors discovered that when D2 / R≤0.8, the difference in the current path between different parts of the first electrode tab 11 and the electrode terminal 30 is reduced, thereby improving the uniformity of the current density of the first electrode plate of the electrode assembly 10, reducing the internal resistance, and improving the overcurrent capability.

[0234] Optionally, D2 / R can be 0.2, 0.3, 0.5, 0.7 or 0.8.

[0235] In some embodiments, after in-depth research and extensive experiments, the inventors discovered that when D2 and R satisfy: 0.2≤D2 / R≤0.5, the overcurrent capability of the battery cell 7 can be improved and the temperature rise of the battery cell can be reduced.

[0236] In some embodiments, D2 is 3.5mm-10mm.

[0237] If D2 is too small, the current-carrying area between the current collector 40 and the connecting part 32 will be insufficient, and the weld between the current collector 40 and the connecting part 32 will generate a large amount of heat during charging and discharging, making it difficult to meet the requirements of the battery cell 7 for current carrying capacity and temperature rise during fast charging. After in-depth research and a large number of experiments, the inventors found that when D2 ≥ 3.5 mm, the requirements of the battery cell 7 for current carrying capacity and temperature rise can be met.

[0238] If D2 is too large, it will result in fewer tab layers connected to the third welding part W3, and the distance between the tab layer near the central axis A and the third welding part W3 will be too large, leading to a higher internal resistance of the electrode assembly 10 and affecting the performance of the battery cell 7. After in-depth research and extensive experiments, the inventors discovered that when D2 ≤ 10 mm, the internal resistance of the electrode assembly 10 can be reduced, improving the charge and discharge performance of the battery cell 7.

[0239] Optionally, D2 can be 3.5mm, 4mm, 5mm, 7mm, 8.5mm or 10mm.

[0240] In some embodiments, R is 20mm-22.8mm.

[0241] In some embodiments, the third welding portion W3 is annular. The annular third welding portion W3 has a large current-carrying area, which can improve the uniformity of the current density of the first electrode, reduce the internal resistance, and improve the current-carrying capacity.

[0242] In some embodiments, the diameter of the current collector 40 is D3, and the diameter of the first electrode 11 is D4, where D3 is smaller than D4.

[0243] D3 refers to the diameter of the outer edge of the current collector 40, that is, the outer diameter of the current collector 40. D4 refers to the diameter of the outer edge of the first electrode 11, that is, the outer diameter of the first electrode 11. For example, D4 ​​= 2*R.

[0244] The current collector 40 has a smaller diameter, which saves space and weight occupied by the current collector 40 and increases the energy density of the battery cell 7.

[0245] In some embodiments, D3 and D4 satisfy: 0.75≤D3 / D4≤0.97.

[0246] When D4 is constant, if D3 is too small, the distance between the outer part of the first tab 11 and the current collector 40 will be too large, resulting in an excessively long conductive path between them. This leads to a high internal resistance of the electrode assembly 10, affecting the performance of the battery cell 7. After in-depth research and numerous experiments, the inventors discovered that when D3 / D4 ≥ 0.75, the internal resistance of the electrode assembly 10 can be reduced, improving the charge and discharge performance of the battery cell 7.

[0247] When D4 is constant, if D3 is too large, the coaxiality of the current collector 40 and the electrode assembly 10 will fluctuate due to assembly errors. This will cause the current collector 40 to protrude from the outer peripheral surface of the electrode assembly 10, making it difficult for the current collector 40 and the electrode assembly 10 to fit into the housing, thus affecting assembly efficiency and product yield. After in-depth research and extensive experiments, the inventors discovered that when D3 / D4 ≤ 0.97, the risk of the current collector 40 protruding from the outer peripheral surface of the electrode assembly 10 due to errors can be reduced, thereby improving assembly efficiency and product yield.

[0248] Alternatively, D3 / D4 can be 0.75, 0.8, 0.85, 0.9, 0.95 or 0.97.

[0249] In some embodiments, D3 is 35mm-44mm. After in-depth research and extensive experiments, the inventors discovered that limiting D3 to 35mm-44mm can reduce the internal resistance of the electrode assembly 10, improve the charge and discharge performance of the battery cell 7, and reduce the risk of the current collector 40 protruding from the outer peripheral surface of the electrode assembly 10 due to errors.

[0250] Alternatively, D3 can be 35mm, 38mm, 40mm, 41mm, 43mm or 44mm.

[0251] In some embodiments, after in-depth research and extensive experiments, the inventors found that limiting D3 to 38mm-41mm can better reduce the internal resistance of the electrode assembly 10 and improve the charge and discharge performance of the battery cell 7.

[0252] In some embodiments, the connecting portion 32 is provided with a groove 324 recessed from the first outer surface 322 of the connecting portion 32 in the direction facing the electrode assembly 10, and the first welding portion W1 extends from the bottom wall of the groove 324 to at least the interior of the current collector 40.

[0253] The connecting portion 32 has a first outer surface 322 and a first inner surface 321 disposed opposite to each other along its own thickness direction X. The first inner surface 321 faces the flow collecting member 40, and the first outer surface 322 faces away from the flow collecting member 40. Optionally, both the first outer surface 322 and the first inner surface 321 are planar.

[0254] The groove 324 is recessed relative to the first outer surface 322 in the direction facing the flow collector 40. In this embodiment, by forming the groove 324 on the connecting portion 32, a stepped structure is formed on the connecting portion 32. A gap is formed between the first outer surface 322 and the bottom wall of the groove 324.

[0255] The portion between the bottom wall of the groove 324 and the first inner surface 321 can be the area of ​​the connecting portion 32 for welding to the current collecting member 40. In other words, the portion between the bottom wall of the groove 324 and the first inner surface 321 is used for welding to the current collecting member 40 to form the first weld portion W1.

[0256] During the production of the battery cell 7, external equipment needs to cooperate with the connecting part 32. The surface of the first welding part W1 is uneven, and if the external equipment is pressed onto the first welding part W1, the external equipment is easily damaged by the first welding part W1. In this embodiment, a groove 324 is provided to form a gap between the first outer surface 322 and the bottom wall of the groove 324. In this way, the first outer surface 322 can be used to support the external equipment, thereby separating the external equipment from the first welding part W1 and reducing the risk of the external equipment being damaged.

[0257] For example, the external device may be a liquid injection device, a vacuuming device, a welding device, or other device used for the battery cell 7.

[0258] In some embodiments, the connecting portion 32 is provided with a first through hole 323, which is used to connect the space on the side of the connecting portion 32 away from the electrode assembly 10 to the internal space of the housing 20.

[0259] The first through hole 323 extends through the connecting portion 32 along the thickness direction X. There can be one or more first through holes 323.

[0260] When welding the connection 32 and the current collecting member 40, the first through hole 323 can release welding stress and reduce the risk of the connection 32 breaking.

[0261] During the molding process of the battery cell 7, the first through hole 323 can be used in multiple molding processes. For example, the first through hole 323 can be applied to the liquid injection process, the formation process, or other processes.

[0262] Specifically, the first through hole 323 is used to inject electrolyte into the internal space of the housing 20. When electrolyte injection is required, the injection head of the injection device presses against the connection 32, and then the injection head injects electrolyte into the housing 20 through the first through hole 323.

[0263] During the formation process of the battery cell 7, gas is generated inside the casing 20. The first through hole 323 can also be used to connect with an external negative pressure device to extract the gas inside the casing 20.

[0264] In some embodiments, the axis of the first through hole 323 coincides with the axis of the electrode lead-out hole 221.

[0265] In some embodiments, the current collector 40 is provided with a second through hole 45, which is configured to be opposite to the first through hole 323 so that the electrolyte can flow into the internal space of the housing 20 through the second through hole 45.

[0266] The axial direction of the first through hole 323 is parallel to the axial direction of the second through hole 45. Along the axial direction of the first through hole 323, the projection of the first through hole 323 at least partially overlaps with the projection of the second through hole 45. This embodiment does not limit the diameter of the second through hole 45; it can be greater than, equal to, or smaller than the diameter of the first through hole 323.

[0267] In this embodiment, by providing a second through hole 45 on the current collector 40 that is opposite to the first through hole 323, the current collector 40 reduces the obstruction of the electrolyte by the current collector 40 during the electrolyte injection process, so that the electrolyte can flow smoothly into the housing 20 and improve the wetting efficiency of the electrode assembly 10.

[0268] In some embodiments, the projection of the first through hole 323 is located within the projection of the second through hole 45 along its axial direction. This embodiment can prevent the current collector 40 from blocking the first through hole 323, allowing the electrolyte to flow smoothly into the housing 20.

[0269] The first through hole 323 and the second through hole 45 are coaxially arranged, and the diameter of the second through hole 45 can be greater than or equal to the diameter of the first through hole 323.

[0270] In some embodiments, the electrode assembly 10 is a wound structure, and the electrode assembly 10 has a third through hole 14 at the center of the winding. The third through hole 14 passes through the electrode assembly 10 and is disposed opposite to the first through hole 323 and the second through hole 45, so that the electrolyte can flow into the interior of the electrode assembly 10 through the third through hole 14.

[0271] The electrode assembly 10 is manufactured by winding a first electrode, a second electrode, and a spacer onto a winding tool. After winding, the winding tool is removed from the electrode assembly 10. After the winding tool is removed, a third through hole 14 is formed in the middle of the electrode assembly 10.

[0272] The axial direction of the third through hole 14 may be parallel to the axial direction of the first through hole 323. The axis of the third through hole 14 coincides with the central axis A of the electrode assembly 10. The third through hole 14 passes through the first electrode tab 11, the main body 12, and the second electrode tab 13.

[0273] During the electrolyte injection process, the electrolyte can flow into the third through hole 14 through the first through hole 323 and the second through hole 45. The electrolyte flowing into the third through hole 14 can wet the electrode assembly 10 from the inside, thereby improving the wetting efficiency of the electrode assembly 10.

[0274] In some embodiments, the projection of the second through hole 45 is located within the projection of the third through hole 14 in the axial direction of the third through hole 14. This reduces the obstruction of the second through hole 45 by the first electrode tab 11, allowing the electrolyte to flow smoothly into the third through hole 14.

[0275] In some embodiments, the first through hole 323, the second through hole 45, and the third through hole 14 are coaxially arranged. The diameter of the third through hole 14 may be greater than or equal to the diameter of the second through hole 45.

[0276] In some embodiments, the first through hole 323 extends from the bottom wall of the groove 324 to the first inner surface 321 to pass through the connection portion 32. During electrolyte injection, the injection head presses against the first outer surface 322, which can support the injection head and cooperate with it to achieve a seal, reducing the risk of electrolyte leakage to the outside of the battery cell 7.

[0277] Figure 12 This is a schematic diagram of the electrode assembly and current collector of a battery cell according to other embodiments of this application.

[0278] like Figure 12 As shown, there are multiple third welding parts W3, and the multiple third welding parts W3 are arranged at intervals along the circumferential Y direction of the first electrode tab 11.

[0279] The third welding part W3 can be a straight structure extending radially along the electrode assembly 10, or it can be a V-shaped mechanism, or of course, other structures.

[0280] Multiple third welding sections W3 can increase the current-carrying area, improve the uniformity of the current density of the first electrode, reduce internal resistance, and improve the current-carrying capacity.

[0281] Figure 13 This is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application. Figure 14 for Figure 13 Enlarged view at box E.

[0282] like Figure 13 and Figure 14 As shown, in some embodiments, the first portion 111 is welded to the current collector 40 and forms the second welded portion W2.

[0283] The second welded portion W2 can reduce the contact resistance between the current collector 40 and the first tab 11, thereby improving the current carrying capacity. The second welded portion W2 is close to the connecting portion 32, which reduces the conductive path between the connecting portion 32 and the second welded portion W2, thus reducing resistance and improving the current carrying capacity.

[0284] In some embodiments, the first welding part W1 and the second welding part W2 are integrated. The current on the first electrode tab 11 can be conducted to the electrode terminal 30 through the second welding part W2 and the first welding part W1, thereby shortening the conductive path, reducing resistance, and improving the overcurrent capacity.

[0285] In some embodiments, when welding the connection 32 and the current collector 40, the current collector 40 can be melted through, and a first welded part W1 and a second welded part W2 can be formed simultaneously.

[0286] Figure 15 An exploded view of the electrode terminals of a battery cell provided in some embodiments of this application; Figure 16 This is a top view of the electrode terminals of a battery cell provided in some embodiments of this application.

[0287] Please refer to the above as well. Figures 13 to 16 In some embodiments, the housing 20 includes a cylindrical body 21 and a cover 22 connected to the cylindrical body 21. The cylindrical body 21 is disposed around the outer periphery of the electrode assembly 10. The cover 22 is provided with an electrode lead-out hole 221, and the electrode terminal 30 is installed in the electrode lead-out hole 221. The electrode terminal 30 includes a terminal body 34. The terminal body 34 includes a columnar portion 341, a first limiting portion 342, and a second limiting portion 343. At least a portion of the columnar portion 341 is located within the electrode lead-out hole 221. A first recess 31 is provided in the columnar portion 341. The first limiting portion 342 and the second limiting portion 343 are both connected to and protrude from the outer side wall of the columnar portion 341. The first limiting portion 342 and the second limiting portion 343 are respectively provided on the outer side and the inner side of the cover 22 and are used to clamp a portion of the cover 22.

[0288] The first limiting part 342 is located on the outer side of the cover 22, meaning that the first limiting part 342 is located on the side of the cover 22 away from the electrode assembly 10; the second limiting part 343 is located on the inner side of the cover 22, meaning that the second limiting part 343 is located on the side of the cover 22 facing the electrode assembly 10.

[0289] In the thickness direction of the cover 22, at least a portion of the first limiting portion 342 overlaps with the cover 22, and at least a portion of the second limiting portion 343 overlaps with the cover 22. A columnar portion 341 passes through the electrode lead-out hole 221 to connect the first limiting portion 342 and the second limiting portion 343 located on both sides of the cover 22.

[0290] The first limiting part 342 and the second limiting part 343 clamp a portion of the cover 22 from both sides to fix the terminal body 34 to the cover 22. The first limiting part 342 and the second limiting part 343 can clamp the cover 22 directly or indirectly through other components.

[0291] Optionally, the columnar portion 341 is cylindrical. The first limiting portion 342 and the second limiting portion 343 are both annular structures surrounding the columnar portion 341.

[0292] In some embodiments, the battery cell 7 further includes a first insulating member 60 and a second insulating member 70. At least a portion of the first insulating member 60 is disposed between the first limiting portion 342 and the cover 22, and at least a portion of the second insulating member 70 is disposed between the second limiting portion 343 and the cover 22. The first insulating member 60 and the second insulating member 70 are used to insulate and isolate the terminal body 34 from the cover 22.

[0293] Both the first insulating member 60 and the second insulating member 70 are annular structures arranged around the columnar portion 341.

[0294] The first insulating member 60 can insulate and isolate the first limiting part 342 from the cover 22, and the second insulating member 70 can insulate and isolate the second limiting part 343 from the cover 22.

[0295] In some embodiments, one of the first insulating member 60 and the second insulating member 70 separates the columnar portion 341 and the cover 22. For example, a portion of the first insulating member 60 extends into the electrode lead-out hole 221 to separate the hole wall of the electrode lead-out hole 221 from the columnar portion 341.

[0296] In some embodiments, the first insulating member 60 and the second insulating member 70 are integrally formed. Alternatively, in other embodiments, the first insulating member 60 and the second insulating member 70 are provided separately and abut against each other.

[0297] In some embodiments, one of the first insulating member 60 and the second insulating member 70 is used to seal the electrode lead-out hole 221. In some examples, the first limiting portion 342 and the cover 22 press against the first insulating member 60, compressing the first insulating member 60 and sealing the electrode lead-out hole 221 from the outside. In other examples, the second limiting portion 343 and the cover 22 press against the second insulating member 70, compressing the second insulating member 70 and sealing the electrode lead-out hole 221 from the inside.

[0298] In some embodiments, the battery cell 7 further includes a sealing ring 80, which is fitted onto the columnar portion 341 and used to seal the electrode lead-out hole 221. Optionally, a portion of the sealing ring 80 extends into the electrode lead-out hole 221 to separate the hole wall of the electrode lead-out hole 221 from the columnar portion 341.

[0299] In some embodiments, the outer periphery of the first limiting portion 342 is provided with a plurality of protrusions 342a, and the plurality of protrusions 342a are arranged at intervals along the circumferential direction of the columnar portion 341.

[0300] Optionally, the multiple protrusions 342a can be arranged at equal intervals along the circumference of the columnar portion 341.

[0301] The first limiting part 342 is a flange structure formed by folding the end of the terminal body 34 away from the electrode assembly 10 outward.

[0302] Before the terminal body 34 is assembled to the housing 20, the first limiting portion 342 of the terminal body 34 is generally cylindrical and located at the upper end of the columnar portion 341, with the outer side wall of the first limiting portion 342 flush with the outer side wall of the columnar portion 341. When assembling the terminal body 34 and the housing 20, the first limiting portion 342 is passed through the electrode lead-out hole 221, and then the first limiting portion 342 is folded outward by pressing it, and the terminal body 34 is riveted to the cover 22.

[0303] Before the first limiting portion 342 is folded over, a plurality of spaced-apart groove structures 342b are formed on the upper end of the first limiting portion 342; after the first limiting portion 342 is folded over, a plurality of spaced-apart protrusion structures 342a are formed along the circumference of the columnar portion 341, and the groove structures 342b are between adjacent protrusion structures 342a. In this embodiment, by providing groove structures 342b and protrusion structures 342a, the difficulty of folding the first limiting portion 342 is reduced, and the stress concentration on the first limiting portion 342 is reduced.

[0304] In some embodiments, the second limiting portion 343 is a limiting structure formed by pressing the end of the terminal body 34 facing the electrode assembly 10 to extend the end of the terminal body 34 facing the electrode assembly 10 outward. When assembling the cover 22 and the terminal body 34, an external device can press the end of the terminal body 34 facing the electrode assembly 10, and the end of the terminal body 34 facing the electrode assembly 10 extends outward under pressure to form the protruding second limiting portion 343.

[0305] In some embodiments, the terminal body 34 has a second outer surface 344, and a first recess 31 is recessed from the second outer surface 344 in the direction facing the electrode assembly 10 to the first outer surface 322 of the connection portion 32.

[0306] The terminal body 34 has a second outer surface 344 and a second inner surface 345 disposed opposite to each other. The second inner surface 345 faces the electrode assembly 10, and the second outer surface 344 faces away from the electrode assembly 10. A first recess 31 is recessed from the second outer surface 344 in the direction facing the electrode assembly 10 to the first outer surface 322 of the connecting portion 32.

[0307] In some embodiments, the electrode terminal 30 further includes a sealing plate 33, which is connected to the terminal body 34 and closes the opening of the first recess 31.

[0308] The sealing plate 33 can be located entirely outside the first recess 31, or it can be partially accommodated within the first recess 31, as long as the sealing plate 33 can close the opening of the first recess 31.

[0309] The sealing plate 33 can protect the connection part 32 from the outside, reduce the external impurities entering the first recess 31, reduce the risk of the connection part 32 being damaged by external impurities, and improve the sealing performance of the battery cell 7.

[0310] In addition, the sealing plate 33 also serves to seal the first through hole 323. After the battery cell 7 is formed, the sealing plate 33 can reduce the risk of electrolyte leakage through the first through hole 323 and the first recess 31, thereby improving the sealing performance.

[0311] In some embodiments, a stepped surface 311 is provided on the sidewall of the first recess 31, at least a portion of the sealing plate 33 is accommodated in the first recess 31, and the stepped surface 311 is used to support the sealing plate 33.

[0312] The first recess 31 is a stepped recess that is larger on the outside and smaller on the inside.

[0313] When assembling the sealing plate 33, the stepped surface 311 can support and position the sealing plate 33, thereby simplifying the assembly process. At least a portion of the sealing plate 33 is accommodated in the first recess 31, which can reduce the overall size of the electrode terminal 30, reduce the space occupied by the electrode terminal 30, and increase the energy density.

[0314] In some embodiments, the sealing plate 33 is welded to the sidewall of the first recess 31 to close the opening of the first recess 31.

[0315] In some embodiments, a gap is provided between the sealing plate 33 and the connecting portion 32, the gap being used to avoid the first welding portion W1.

[0316] The surface of the first welded part W1 is uneven. If the sealing plate 33 presses against the first welded part W1, it will cause the sealing plate 33 to wobble during assembly, affecting the sealing effect. In this embodiment, a gap is provided between the sealing plate 33 and the connecting part 32 to avoid direct contact between the sealing plate 33 and the first welded part W1, thereby reducing the wobble of the sealing plate 33 during assembly and ensuring the sealing effect.

[0317] In some examples, the first recess 31 has a stepped structure, such that the sealing plate 33 abuts against the stepped surface 311 to form a gap between the sealing plate 33 and the connecting portion 32. In other examples, the connecting portion 32 may also be provided with a stepped structure, such that the sealing plate 33 can abut against the connecting portion 32, and the groove 324 on the connecting portion 32 forms a gap between the sealing plate 33 and the connecting portion 32.

[0318] In some embodiments, the sealing plate 33 may be welded to the busbar of the battery. In the battery, the busbar may connect the sealing plate 33 of one battery cell 7 and the cover 22 of another battery cell 7 to connect the two battery cells 7 in series.

[0319] In some embodiments, at least a portion of the sealing plate 33 protrudes from the second outer surface 344 of the terminal body 34.

[0320] When it is necessary to weld the busbar component and the sealing plate 33, first attach the busbar component to the upper surface of the sealing plate 33 (i.e., the outer surface of the sealing plate 33 opposite to the connecting part 32), and then weld the busbar component and the sealing plate 33.

[0321] At least a portion of the sealing plate 33 protrudes from the second outer surface 344 to avoid the second outer surface 344 interfering with the fit between the sealing plate 33 and the busbar component, thus ensuring a tight fit between the busbar component and the sealing plate 33.

[0322] In some embodiments, the connecting portion 32 is disposed at one end of the terminal body 34 facing the electrode assembly 10, and the first inner surface 321 and the second inner surface 345 of the connecting portion 32 are flush.

[0323] The second inner surface 345 is the surface of the terminal body 34 facing the electrode assembly 10. The first inner surface 321 of the connecting portion 32 forms a part of the second inner surface 345. In this way, the terminal body 34 can mate with the current collector 40 having a flat plate structure. In this embodiment, the connecting portion 32 and the current collector 40 can be attached to the second inner surface 345 to facilitate welding of the connecting portion 32 and the current collector 40.

[0324] Figure 17 This is a partial cross-sectional schematic diagram of a battery cell provided for other embodiments of this application.

[0325] like Figure 17 As shown, in some embodiments, the terminal body 34 has a second outer surface 344 and a second inner surface 345 disposed opposite to each other, and a first recess 31 is recessed from the second outer surface 344 in a direction facing the electrode assembly 10 to the first outer surface 322 of the connecting portion 32. The terminal body 34 also includes a third recess 35, which is recessed from the second inner surface 345 in a direction away from the electrode assembly 10 to the first inner surface 321 of the connecting portion 32.

[0326] This embodiment of the application reduces the thickness of the connecting portion 32 by simultaneously providing the first recess 31 and the third recess 35. This reduces the depth requirement of the first recess 31 and simplifies the molding process. Providing the third recess 35 also increases the internal space of the battery cell 7, thereby improving energy density.

[0327] In some embodiments, the current collector 40 includes a terminal connection portion 46 and a tab connection portion 47 surrounding the outside of the terminal connection portion 46. The terminal connection portion 46 protrudes from the tab connection portion 47 and extends into the third recess 35, such that the top of the terminal connection portion 46 abuts against the first inner surface 321 of the connection portion 32.

[0328] The tab connection portion 47 is located between the cover 22 and the first tab 11, welded to the second part 112, and forms the third weld portion W3. Optionally, the tab connection portion 47 may be a ring-shaped flat plate structure.

[0329] In some embodiments, the current collector 40 has a fourth recess 48 at a position corresponding to the terminal connection portion 46. The fourth recess 48 is recessed relative to the surface of the electrode connection portion 47 facing the first electrode 11. The fourth recess 48 can reduce the space occupied by the terminal connection portion 46 and reduce the weight of the current collector 40. Exemplarily, the terminal connection portion 46 and the fourth recess 48 are formed by stamping the current collector 40.

[0330] Figure 18 This is a partial cross-sectional schematic diagram of a battery cell provided for some embodiments of this application.

[0331] like Figure 18 As shown, in some embodiments, the terminal body 34 has a second outer surface 344 and a second inner surface 345 disposed opposite to each other, and a first recess 31 is recessed from the second inner surface 345 in a direction away from the electrode assembly 10 to the first inner surface 321 of the connection portion 32.

[0332] In this embodiment, the first recess 31 is disposed on the inner side of the terminal body 34, which ensures the flatness and area of ​​the second outer surface 344, facilitating the connection between the terminal body 34 and external busbar components. Providing the first recess 31 on the inner side of the terminal body 34 also increases the internal space of the battery cell 7, thereby improving energy density.

[0333] In some embodiments, the current collector 40 includes a terminal connection portion 46 and an electrode connection portion 47 surrounding the outside of the terminal connection portion 46. The terminal connection portion 46 protrudes from the electrode connection portion 47 and extends into the first recess 31, such that the top of the terminal connection portion 46 abuts against the first inner surface 321 of the connection portion 32.

[0334] The tab connection portion 47 is located between the cover 22 and the first tab 11, welded to the second part 112, and forms the third weld portion W3. Optionally, the tab connection portion 47 may be a ring-shaped flat plate structure.

[0335] In some embodiments, the current collector 40 has a fourth recess 48 at a position corresponding to the terminal connection portion 46. The fourth recess 48 is recessed relative to the surface of the electrode connection portion 47 facing the first electrode 11. The fourth recess 48 can reduce the space occupied by the terminal connection portion 46 and reduce the weight of the current collector 40. Exemplarily, the terminal connection portion 46 and the fourth recess 48 are formed by stamping the current collector 40.

[0336] Figure 19 This is a cross-sectional schematic diagram of a battery cell provided for other embodiments of this application.

[0337] like Figure 19 As shown, in some embodiments, the battery cell 7 may be a square battery cell.

[0338] In some embodiments, the housing 20 includes an integrally formed cylindrical body 21 and a cover 22, the cylindrical body 21 being disposed around the outer periphery of the electrode assembly 10. Exemplarily, the cylindrical body 21 may be a square tube.

[0339] The cylinder 21 has an opening at the end opposite to the cover 22, and the cover plate 50 covers the opening of the cylinder 21 to close the opening. Exemplarily, the cover plate 50 is welded to the cylinder 21.

[0340] In some embodiments, the battery cell further includes a first electrode terminal 30 and a second electrode terminal 90 with opposite polarities. The first electrode terminal 30 is used to be electrically connected to a first tab of the electrode assembly 10, and the second electrode terminal 90 is used to be electrically connected to a second tab of the electrode assembly 10.

[0341] In some embodiments, the first electrode terminal 30 and the second electrode terminal 90 are both mounted on the cover 22.

[0342] In a battery, a busbar connects the electrode terminals of multiple battery cells to connect them in series, parallel, or mixed connections. Both the first electrode terminal 30 and the second electrode terminal 90 can be used to connect to the busbar.

[0343] When the battery is subjected to an external impact, the busbar component pulls on the cover 22 through the first electrode terminal 30 and the second electrode terminal 90, thereby subjecting the connection between the cover 22 and the cylindrical body 21 to force. If the cover 22 and the cylindrical body 21 are separate structures, for example, if the cover 22 and the cylindrical body 21 are connected by welding, then the connection between the cover 22 and the cylindrical body 21 may fail under the force. In the embodiments of this application, the cover 22 and the cylindrical body 21 are integrally formed, thereby improving the strength of the connection between the cover 22 and the cylindrical body 21 and reducing the risk of connection failure.

[0344] In some embodiments, the housing 20 is not electrically connected to either the positive or negative electrode of the electrode assembly. In other words, the housing 20 is not charged.

[0345] In some embodiments, the first tab and the second tab of the electrode assembly 10 are located on the same side of the electrode assembly facing the cover 22.

[0346] According to some embodiments of this application, a battery is also provided, comprising a plurality of battery cells of any of the above embodiments.

[0347] According to some embodiments of this application, an electrical device is also provided, including the battery of any of the above embodiments, the battery being used to provide electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems that utilize a single battery cell.

[0348] Reference Figures 4 to 6 According to some embodiments of this application, a cylindrical battery cell 7 is provided, including an electrode assembly 10, a housing 20, electrode terminals 30, a current collector 40, and a cover plate 50.

[0349] The housing 20 includes an integrally formed cylindrical body 21 and a cover 22. The cylindrical body 21 is disposed around the outer periphery of the electrode assembly 10, and the cover 22 is provided with an electrode lead-out hole 221, into which the electrode terminal 30 is installed. The cylindrical body 21 has an opening at the end opposite to the cover 22, and a cover plate 50 is fitted onto the opening of the cylindrical body 21 to close the opening of the cylindrical body 21.

[0350] The electrode assembly 10 includes a main body 12, a first electrode tab 11, and a second electrode tab 13, which protrude from the main body 12. The first electrode tab 11 is located at the end of the electrode assembly 10 facing the electrode terminal 30, and the second electrode tab 13 is located at the end of the electrode assembly 10 away from the electrode terminal 30.

[0351] The electrode terminal 30 includes a terminal body 34 and a sealing plate 33. The terminal body 34 includes a first recess 31 and a connecting portion 32 located at the bottom of the first recess 31. The sealing plate 33 is connected to the terminal body 34 and closes the opening of the first recess 31.

[0352] The current collector 40 is welded to the first electrode 11 and the connecting part 32 to electrically connect the first electrode 11 and the connecting part 32.

[0353] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0354] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A battery cell, characterized in that, include: Electrode assembly, including a first electrode tab; A housing for accommodating the electrode assembly, the electrode assembly being a wound structure; Electrode terminals are disposed in the housing, the electrode terminals including a first recess and a connecting portion located at the bottom of the first recess; and A current collector is connected to the first electrode tab and welded to the connecting part.

2. The battery cell according to claim 1, characterized in that, The current collector is welded to the connecting portion to form a first weld portion, and in the thickness direction of the connecting portion, the first weld portion extends from the side of the connecting portion away from the current collector to at least the interior of the current collector.

3. The battery cell according to claim 2, characterized in that, In the thickness direction of the connection portion, the first weld portion does not extend beyond the surface of the current collecting member that is away from the connection portion.

4. The battery cell according to claim 2, characterized in that, The housing includes a cylindrical body and a cover connected to the cylindrical body. The cylindrical body is arranged around the outer periphery of the electrode assembly, and the cover is provided with an electrode lead-out hole. The electrode terminal is installed in the electrode lead-out hole. Both the first welded part and the cover are annular, the outer diameter of the cover is D0, and the inner diameter of the first welded part is D1; D1 and D0 satisfy: 0.1≤D1 / D0≤0.

6.

5. The battery cell according to claim 4, characterized in that, The first welded part is a non-closed structure, and the central angle of the first welded part is 180°-330°.

6. The battery cell according to claim 4, characterized in that, The first welded part is a closed structure.

7. The battery cell according to claim 4, characterized in that, 0.2≤D1 / D0≤0.

4.

8. The battery cell according to claim 4, characterized in that, D1 is 5mm-14mm.

9. The battery cell according to claim 4, characterized in that, The cover and the cylinder are integrally formed.

10. The battery cell according to claim 2, characterized in that, In the thickness direction of the connecting part, the dimension of the first welding part is h, and the thickness of the area of ​​the connecting part for welding with the current collecting member is d0; d0 and h satisfy: 1 ​​< h / d0 ≤ 1.

5.

11. The battery cell according to claim 10, characterized in that, The thickness of the area of ​​the current collector for welding with the connection part is d1, d0 and d1 satisfy: 0.5≤d1 / d0≤1.

2.

12. The battery cell according to claim 10, characterized in that, d0 is 0.4mm-1.2mm.

13. The battery cell according to claim 1, characterized in that, At least a portion of the first tab is located on the side of the current collector opposite to the electrode terminal and is supported by the current collector.

14. The battery cell according to claim 13, characterized in that, The first portion of the first electrode tab is located on the side of the connecting portion away from the first recess and is used to support the portion of the current collecting member opposite to the connecting portion.

15. The battery cell according to claim 14, characterized in that, The first part is welded to the current collection member to form the second welded part.

16. The battery cell according to claim 14, characterized in that, The second portion of the first electrode surrounds the outer periphery of the first portion and is used to support the area of ​​the current collector that is not opposite to the connecting portion.

17. The battery cell according to claim 16, characterized in that, The second part is welded to the current collection member to form a third welded part.

18. The battery cell according to claim 17, characterized in that, The current collector has a protrusion on the side facing the first electrode tab, and the protrusion is welded to the second portion to form the third weld portion.

19. The battery cell according to claim 17, characterized in that, The first electrode tab is arranged around the central axis of the electrode assembly, and the cross section of the first electrode tab perpendicular to the central axis is annular; The outer radius of the first electrode tab is R, and the minimum distance between the third welding part and the central axis in the radial direction of the first electrode tab is D2. Both satisfy: 0.2≤D2 / R≤0.

8.

20. The battery cell according to claim 19, characterized in that, D2 and R satisfy: 0.2≤D2 / R≤0.

5.

21. The battery cell according to claim 19, characterized in that, D2 is 3.5mm-10mm.

22. The battery cell according to any one of claims 13-21, characterized in that, The diameter of the current collecting component is D3, and the diameter of the first electrode ear is D4, where D3 is smaller than D4.

23. The battery cell according to claim 22, characterized in that, D3 and D4 satisfy: 0.75≤D3 / D4≤0.

97.

24. The battery cell according to claim 22, characterized in that, D3 is 35mm-44mm.

25. The battery cell according to any one of claims 2-12, characterized in that, The connecting portion is provided with a groove recessed from the first outer surface of the connecting portion in the direction facing the electrode assembly, and the first welding portion extends from the bottom wall of the groove to at least the interior of the current collector.

26. The battery cell according to claim 1, characterized in that, The housing includes a cylindrical body and a cover connected to the cylindrical body. The cylindrical body is arranged around the outer periphery of the electrode assembly, and the cover is provided with an electrode lead-out hole. The electrode terminal is installed in the electrode lead-out hole. The electrode terminal includes a terminal body, which includes a columnar portion, a first limiting portion, and a second limiting portion. At least a portion of the columnar portion is located inside the electrode lead-out hole. A first recess is provided in the columnar portion. The first limiting portion and the second limiting portion are both connected to and protrude from the outer side wall of the columnar portion. The first limiting portion and the second limiting portion are respectively provided on the outer side and the inner side of the cover and are used to clamp a portion of the cover.

27. The battery cell according to claim 26, characterized in that, The terminal body has a second outer surface, and the first recess extends from the second outer surface toward the first outer surface of the connection portion in a direction facing the electrode assembly.

28. The battery cell according to claim 26, characterized in that, The electrode terminal also includes a sealing plate, which is connected to the terminal body and closes the opening of the first recess.

29. The battery cell according to claim 1, characterized in that, The electrode assembly further includes a second electrode with a polarity opposite to that of the first electrode, and the second electrode is arranged around the central axis of the electrode assembly; The first electrode tab is located at the end of the electrode assembly facing the electrode terminal, and the second electrode tab is located at the end of the electrode assembly away from the electrode terminal. The second electrode tab is electrically connected to the housing.

30. The battery cell according to claim 29, characterized in that, The second electrode tab is the negative electrode tab, and the base material of the shell is steel.

31. The battery cell according to any one of claims 1-12, characterized in that, The housing has an opening at one end away from the electrode terminals, and the battery cell also includes a cover for closing the opening.

32. A battery, characterized in that, It includes multiple battery cells according to any one of claims 1-31.

33. An electrical appliance, characterized in that, Includes the battery according to claim 32, the battery being used to provide electrical energy.

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