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 according to an embodiment of the present application comprises: a housing having an opening; the electrode assembly is accommodated in the shell, and one end, facing the opening, of the electrode assembly is provided with a first tab; the end cover is used for covering the opening so as to seal the electrode assembly in the shell; and the current collecting component is arranged between the end cover and the first tab, and the current collecting component is configured to be welded with the end cover and the first tab respectively so as to realize electric connection between the end cover and the first tab. The risk that the end cover generates microcracks can be reduced when the end cover is welded, and the sealing performance and safety are improved.

Description

[0001] This application is a divisional application of the application with the application number 202180081157.X, the application date of September 30, 2021, the applicant of Ningde Times New Energy Technology Co., Ltd., and the application name of "Battery Cell and Manufacturing Method and Manufacturing System Thereof, Battery and Electric Device". TECHNICAL FIELD

[0002] The present application relates to the technical field of battery, and more particularly, to a battery cell, a battery and an electric device. BACKGROUND

[0003] Battery cells are widely used in electronic devices, such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, electric tools, and the like. Battery cells can include cadmium-nickel battery cells, hydrogen-nickel battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells, etc.

[0004] In the development of battery technology, in addition to improving the performance of battery cells, safety is also an issue that cannot be ignored. If the safety of the battery cell cannot be guaranteed, the battery cell cannot be used. Therefore, how to enhance the safety of the battery cell is a technical problem to be solved in the battery technology. SUMMARY

[0005] The present application provides a battery cell and a manufacturing method and manufacturing system thereof, a battery and an electric device, which can improve the safety of the battery cell.

[0006] In a first aspect, the embodiments of the present application provide a battery cell, comprising: a shell having an opening; an electrode assembly accommodated in the shell, the electrode assembly having a first tab at one end facing the opening; an end cover for covering the opening to seal the electrode assembly in the shell; a current collecting member arranged between the end cover and the first tab, the current collecting member being configured to be welded with the end cover and the first tab respectively to realize electrical connection of the end cover and the first tab.

[0007] In the above scheme, the current collecting member is welded with the end cover and the first tab respectively to realize electrical connection of the end cover and the first tab. The current collecting member can be tightly attached to the end cover to reduce the risk of micro-cracks of the end cover, improve the sealing performance, reduce the safety hazard, and improve the safety. When the current collecting member is welded with the first tab, even if the current collecting member produces micro-cracks, it will not affect the sealing performance of the battery cell.

[0008] In some embodiments, a portion of the current collecting member is used to abut and weld with the end cover to form a first welding portion, and another portion of the current collecting member is used to abut and weld with the first tab to form a second welding portion. The projection of the first welding portion along the thickness direction of the end cover and the projection of the second welding portion along the thickness direction of the end cover do not overlap.

[0009] In the above scheme, the projection of the first welding portion along the thickness direction of the end cover and the projection of the second welding portion along the thickness direction of the end cover do not overlap, so that the welding of the end cover and the current collecting member is not affected by the second welding portion, and the welding reliability of the end cover and the current collecting member is improved.

[0010] In some embodiments, the electrode assembly is wound along the central axis and forms a first tab, the first tab includes N layer structures arranged around the central axis, and the extension direction of the central axis is parallel to the thickness direction of the end cover. The first tab is composed of a first annular portion and a second annular portion arranged outside the first annular portion, the number of layer structures in the first annular portion is N1, the number of layer structures in the second annular portion is N2, N=N1+N2, the value of |N1-N2| is less than or equal to 2, N1 and N2 are positive integers. The first annular portion is welded with the current collecting member to form a first portion, and the second annular portion is welded with the current collecting member to form a second portion connected to the first portion, and the second welding portion is composed of the first portion and the second portion.

[0011] In the above scheme, the electrons in the region of the electrode assembly corresponding to the first annular portion can move along a first current path formed by the first annular portion, the first portion, the current collecting member, the first welding portion and the end cover, and the electrons in the region of the electrode assembly corresponding to the second annular portion can move along a second current path formed by the second annular portion, the second portion, the current collecting member, the first welding portion and the end cover, and the boundary between the first annular portion and the second annular portion is located at the middle region of the first tab in the radial direction, that is, some layer structures in the middle region of the first tab are welded with the current collecting member to form part of the second welding portion, so that the difference between the first current path and the second current path can be reduced to a certain extent, the uniformity of the current density is improved, the internal resistance is reduced, and the overcurrent capacity is improved.

[0012] In some embodiments, N3 consecutive layer structures in the first annular portion arranged close to the second annular portion are welded with the current collecting member to form the first portion, and N4 consecutive layer structures in the second annular portion arranged close to the first annular portion are welded with the current collecting member to form the second portion, the N3 consecutive layer structures and the N4 consecutive layer structures are arranged continuously, N4>N3≥1, and N3 and N4 are positive integers.

[0013] In the above scheme, since the second annular portion surrounds the outside of the first annular portion, the circumference of the layer structure in the second annular portion is greater than the circumference of the layer structure in the first annular portion, and the path of the electrons in the electrode assembly corresponding to the second annular portion between the layer structures in the second annular portion is longer. In the scheme, N4>N3, so that the layer structure connected with the second portion can be increased, the transmission of the electrons between the layer structures in the second annular portion can be reduced, and thus the second current path is shortened, the difference between the first current path and the second current path is further reduced, the uniformity of the current density is improved, the internal resistance is reduced, and the overcurrent capacity is improved.

[0014] In some embodiments, M consecutive layer structures in all the layer structures are welded with the current collecting member and form the second welding portion, where 1 / 3≤M / N≤1 / 2, M≥2, and M is a positive integer.

[0015] The greater the value of M / N is, the smaller the internal resistance of the first tab is, the greater the area of the second welding portion is, and the stronger the overcurrent capacity between the first tab and the current collecting member is. However, when the area of the current collecting member is constant, the greater the value of M / N is, the smaller the area of the first welding portion is, and the lower the overcurrent capacity between the current collecting member and the end cover is. The above scheme limits the value of M / N to 1 / 3-1 / 2, so as to balance the overcurrent capacity between the first tab and the current collecting member and the overcurrent capacity between the current collecting member and the end cover, and optimize the overcurrent capacity of the battery monomer.

[0016] In some embodiments, the end cover comprises a cover body and a first protruding portion protruding from the inner surface of the cover body in a direction facing the first tab, the first protruding portion is used to abut and weld with the current collecting member to form the first welding portion, and the first avoiding gap for avoiding the second welding portion is formed between the current collecting member and the cover body.

[0017] In the above scheme, by providing the first avoiding gap for avoiding the second welding portion, the risk that the second welding portion is pressed against the cover body is reduced. If the second welding portion abuts against the cover body, overpositioning is formed between the end cover and the current collecting member, and the second welding portion interferes with the abutment of the first protruding portion and the current collecting member. In the scheme, the first avoiding gap is provided, so that the second welding portion does not interfere with the abutment of the first protruding portion and the current collecting member, and the connection strength of the first protruding portion and the current collecting member is ensured.

[0018] In some embodiments, a first recess is formed on the end cover at a position corresponding to the first protruding portion, the first recess is recessed from the outer surface of the cover body in a direction facing the electrode assembly, and the bottom surface of the first recess is closer to the first tab than the inner surface of the cover body.

[0019] In the above scheme, the first protrusion thickness is reduced by setting the first recess, so that the welding power required for welding the first protrusion and the current collecting member is reduced, heat generation is reduced, and the risk of burning other components is reduced. The first recess can reduce the strength of the first protrusion and improve the elastic deformation capability of the first protrusion, so that in the process of pressing the first protrusion against the current collecting member, the first protrusion can release stress by deforming, reduce the impact force, and reduce the risk of crushing the current collecting member and the first tab. The present scheme further ensures the degree of recess of the first recess on the premise of ensuring the degree of protrusion of the first protrusion, so as to improve the elastic deformation capability of the first protrusion and reduce the risk of crushing the current collecting member and the first tab during assembly.

[0020] In some embodiments, the first protrusion is arranged outside the cover body, and the first welding portion is arranged outside the second welding portion.

[0021] In some embodiments, the outer side surface of the first protrusion abuts against the inner surface of the shell and is used for welding with the shell to close the opening.

[0022] In the above scheme, welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and overcurrent capacity between the shell and the first protrusion.

[0023] In some embodiments, the end cover further comprises an extension portion arranged outside the first protrusion, and a surface of the extension portion facing the first tab abuts against and is welded with an end surface of the shell surrounding the opening to close the opening.

[0024] In the above scheme, when the end cover and the shell are assembled, the end surface of the shell can function as a limiting part in the thickness direction, reducing the risk of excessive insertion of the end cover into the shell and improving the assembly efficiency.

[0025] In some embodiments, the battery monomer is a cylindrical battery monomer, and in the radial direction of the battery monomer, the extension portion does not exceed the outer surface of the side wall outwardly.

[0026] In some embodiments, the end cover further comprises a second protrusion, the cover body is arranged outside the second protrusion, and the second protrusion protrudes from the inner surface of the cover body in a direction facing the first tab. A second recess is formed on the end cover at a position corresponding to the second protrusion, and the second recess is recessed from the outer surface of the cover body in a direction facing the electrode assembly.

[0027] In the above scheme, by setting the second protrusion and the second recess in the middle part of the end cover, the strength of the end cover can be increased, and the deformation of the end cover can be reduced.

[0028] In some embodiments, a weak part is arranged at a region of the second protrusion opposite to the bottom surface of the second recess, and the weak part is used for breaking when the internal pressure of the battery monomer reaches a threshold value to release the internal pressure.

[0029] In the above scheme, the weak part is arranged on the second protrusion to release the internal pressure when the battery cell is in thermal runaway, thereby improving the safety performance. The weak part is formed in the area opposite to the bottom surface of the second recess of the second protrusion, so that the distance between the weak part and other external components is increased, and the risk of the weak part being pressed by the external components is reduced.

[0030] In some embodiments, a second avoiding gap is formed between the second protrusion and the current collecting member.

[0031] In the above scheme, the second avoiding gap is formed between the second protrusion and the current collecting member to reduce the risk of the current collecting member blocking the exhaust passage when the weak part is broken, to ensure smooth exhaust, and to reduce the safety risk.

[0032] In some embodiments, the cover body surrounds the outside of the first protrusion, and the first welding part is arranged on the inside of the second welding part.

[0033] In some embodiments, a first recess is formed on the cover in a position corresponding to the first protrusion, and the first recess is recessed from the outer surface of the cover body in a direction facing the electrode assembly. The bottom surface of the first recess is provided with a groove, and the bottom of the groove is used for welding with the current collecting member to form the first welding part.

[0034] In the above scheme, the part of the first protrusion between the bottom surface of the groove and the top surface of the first protrusion forms a connecting part, and the connecting part is used for welding with the current collecting member to form the first welding part. In this scheme, the first recess and the groove are arranged to reduce the thickness of the connecting part of the first protrusion, so that the welding power required for welding the connecting part with the current collecting member is reduced, the heat generation is reduced, and the risk of burning other components is reduced.

[0035] In some embodiments, in the direction of the first tab pointing to the cover, the first welding part does not exceed the bottom surface of the first recess.

[0036] In some embodiments, the cover further comprises a second protrusion surrounding the outside of the cover body, the second protrusion protrudes from the inner surface of the cover body in a direction facing the first tab, and the second protrusion is used for supporting the first tab.

[0037] In the above scheme, the second protrusion can support the first tab to reduce the shaking amplitude of the electrode assembly when the battery cell is shaken, thereby improving the stability of the electrode assembly.

[0038] In some embodiments, the second protrusion is arranged in a spaced manner with the current collecting member.

[0039] In some embodiments, the outside surface of the second protrusion abuts against the inner surface of the shell and is used for welding with the shell to close the opening. The welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and overcurrent capacity between the second protrusion and the shell.

[0040] In some embodiments, in the thickness direction of the end cover, the end surface of the shell surrounding the opening is closer to the first tab than the outer surface of the cover body.

[0041] In some embodiments, a second recess corresponding to the second protrusion is formed on the end cover, the second recess being recessed from the outer surface of the cover body in the direction facing the electrode assembly, and the bottom surface of the second recess being closer to the first tab than the inner surface of the cover body.

[0042] In the above scheme, the second recess can reduce the strength of the second protrusion and improve the elasticity of the second protrusion, so that the second protrusion can release the welding stress by deformation during the welding of the second protrusion and the shell, thereby reducing the risk of deformation and cracking of the welding area and improving the sealing performance. The present scheme further ensures the degree of recess of the second recess on the premise of ensuring the degree of protrusion of the second protrusion, so as to improve the elasticity of the second protrusion and enable the second protrusion to release the welding stress by deformation.

[0043] In some embodiments, the cover body is provided with a weak portion for breaking when the internal pressure of the battery monomer reaches a threshold value to release the internal pressure.

[0044] In the present scheme, the weak portion is provided on the cover body to release the internal pressure when the battery monomer is in thermal runaway, thereby improving the safety performance. The present embodiment forms a first avoiding gap between the current collecting member and the cover body to reduce the risk of the current collecting member blocking the exhaust passage when the weak portion breaks, thereby ensuring smooth exhaust and reducing the safety risk.

[0045] In some embodiments, the current collecting member is a flat plate structure.

[0046] In the above scheme, the flat plate-shaped current collecting member is easier to form. The flat plate-shaped current collecting member can be in contact with the first tab as a whole, thereby increasing the flow area and enabling the current collecting member to more uniformly support the first tab, thereby reducing the risk of the tab of the electrode assembly being offset or misaligned in the thickness direction. The flat plate-shaped current collecting member can also be in close contact with the first protrusion to reduce the risk of micro-cracks of the first protrusion during welding, thereby improving the sealing performance and safety.

[0047] In some embodiments, the first protrusion supports the first tab through the current collecting member.

[0048] In the above scheme, the first protrusion supports the first tab through the current collecting member to reduce the shaking amplitude of the electrode assembly when the battery monomer is shaken, thereby improving the stability of the electrode assembly.

[0049] In some embodiments, the current collecting member comprises: a first current collecting portion configured to abut against and be welded with the end cover to form a first welding portion; and a second current collecting portion configured to abut against and be welded with the first tab to form a second welding portion, the second current collecting portion protruding from a surface of the first current collecting portion facing the electrode assembly, and the second current collecting portion being provided with a recessed portion on a side facing away from the electrode assembly, the recessed portion being configured to avoid interference of the second welding portion with the abutment of the first current collecting portion and the end cover.

[0050] In the above scheme, the recessed portion is configured to avoid interference of the second welding portion with the abutment of the first current collecting portion and the end cover, to ensure the connection strength of the first current collecting portion and the end cover, and to reduce the risk of the second welding portion crushing the end cover. The recessed portion can reduce the thickness of the second current collecting portion, to reduce the welding power required for welding the second current collecting portion and the first tab, to reduce heat generation, and to reduce the risk of other components being burned.

[0051] In some embodiments, the end cover comprises: a cover body configured to be welded with the first current collecting portion to form the first welding portion; and a first protruding portion surrounding an outer side of the cover body and protruding from an inner surface of the cover body in a direction facing the first tab, the first protruding portion being configured to abut against the first tab to support the first tab.

[0052] In the above scheme, the second current collecting portion supports a middle region of the first tab, and the first protruding portion supports an edge region of the first tab, which can improve the uniformity of the force received by the first tab, and reduce the risk of the electrode assembly being offset or misaligned in the thickness direction.

[0053] In some embodiments, a first recessed portion is formed on the end cover at a position corresponding to the first protruding portion, the first recessed portion being recessed from an outer surface of the cover body in a direction facing the electrode assembly, and a bottom surface of the first recessed portion being closer to the first tab than the inner surface of the cover body.

[0054] In the above scheme, the degree of recessing of the first recessed portion is further ensured on the premise of ensuring the degree of protruding of the first protruding portion, to improve the elasticity of the first protruding portion, to reduce the impact force when the first protruding portion is pressed against the first tab, and to reduce the risk of the first tab being crushed.

[0055] In some embodiments, an outer side surface of the first protruding portion abuts against and is welded with an inner surface of the shell to close the opening.

[0056] In the above scheme, welding can achieve sealing, to reduce the risk of leakage of the electrolyte, and to improve the connection strength and overcurrent capacity of the first protruding portion and the shell.

[0057] In some embodiments, the end cover further comprises a second protrusion, the cover body surrounds an outer side of the second protrusion, the second protrusion protrudes from an inner surface of the cover body in a direction facing the first tab and extends into the avoiding recess. A second recess is formed on the end cover corresponding to the second protrusion, the second recess is recessed from an outer surface of the cover body in a direction facing the electrode assembly.

[0058] In the above scheme, the second protrusion and the second recess are arranged in the middle of the end cover, which can increase the strength of the end cover and reduce the deformation of the end cover.

[0059] In some embodiments, a weak part is arranged on an area of the second protrusion opposite to a bottom surface of the second recess, the weak part is used to break when the internal pressure of the battery cell reaches a threshold value to release the internal pressure. The avoiding recess is further used to separate the second current collecting part from the weak part.

[0060] In the above scheme, the weak part is arranged on the second protrusion to release the internal pressure when the battery cell is in thermal runaway, which improves the safety performance. The weak part is formed in an area of the second protrusion opposite to the bottom surface of the second recess, which can increase the distance between the weak part and other external components and reduce the risk of the weak part being pressed by the external components. The avoiding recess can reduce the risk of the current collecting component blocking the exhaust passage when the weak part breaks, ensure smooth exhaust, and reduce the safety risk.

[0061] In some embodiments, the end cover is used to electrically connect the first tab and the shell.

[0062] In the above scheme, the shell itself can serve as an output pole of the battery cell, thereby eliminating a traditional electrode terminal and simplifying the structure of the battery cell. When a plurality of battery cells are assembled into a group, the shell can be electrically connected with the current collecting component, which can not only increase the overcurrent area but also make the structural design of the current collecting component more flexible.

[0063] In some embodiments, the shell further comprises a side wall and a bottom wall connected to the side wall, the side wall extends along the thickness direction of the end cover and surrounds the outer periphery of the electrode assembly, and the bottom wall is provided with an electrode lead-out hole. The electrode assembly further comprises a second tab, the first tab and the second tab are opposite in polarity and are respectively located at two ends of the electrode assembly. The battery cell further comprises an electrode terminal mounted in the electrode lead-out hole, and the electrode terminal is electrically connected to the second tab.

[0064] In the above scheme, the bottom wall and the electrode terminal can serve as two output poles of the battery cell, which can simplify the structure of the battery cell and ensure the overcurrent capacity of the battery cell. The bottom wall and the electrode terminal are located at the same end of the battery cell, so that when a plurality of battery cells are assembled into a group, the current collecting component can be assembled to the same side of the battery cell, which can simplify the assembly process and improve the assembly efficiency.

[0065] In some embodiments, the bottom wall and the side wall are integrally formed. In this way, the connecting process of the bottom wall and the side wall can be omitted.

[0066] In some embodiments, the first tab is a negative tab, and the base material of the shell is steel.

[0067] In the above scheme, the shell is electrically connected with the negative tab, and the shell is in a low potential state. The shell made of steel is not easy to be corroded by the electrolyte in the low potential state, so as to reduce the safety risk.

[0068] In some embodiments, the base material of the shell and the base material of the end cover are the same.

[0069] In the above scheme, the base material of the shell and the base material of the end cover are the same, so as to ensure the welding strength of the shell and the end cover, and ensure the sealing of the battery monomer.

[0070] In some embodiments, the battery monomer is a cylindrical battery monomer.

[0071] In a second aspect, the embodiments of the present application provide a battery, which includes a plurality of the battery monomers of any one of the embodiments of the first aspect.

[0072] In a third aspect, the embodiments of the present application provide a power consumption device, which includes the battery of the second aspect, and the battery is used to provide electric energy.

[0073] In a fourth aspect, the embodiments of the present application provide a manufacturing method of a battery monomer, which includes:

[0074] providing an electrode assembly, the electrode assembly having a first tab;

[0075] providing a current collecting member, and welding the current collecting member to the first tab;

[0076] providing a shell, the shell having an opening;

[0077] installing the electrode assembly and the current collecting member into the shell, and locating the first tab at one end of the electrode assembly facing the opening;

[0078] providing an end cover, and covering the end cover on the opening, so as to seal the electrode assembly in the shell, and locate the current collecting member between the end cover and the first tab;

[0079] welding the end cover and the current collecting member, so as to realize the electrical connection between the end cover and the first tab.

[0080] In a fifth aspect, the embodiments of the present application provide a manufacturing system of a battery monomer, which includes:

[0081] a first providing device, configured to provide an electrode assembly, the electrode assembly having a first tab;

[0082] The second providing device is used to provide a current collector and weld the current collector to the first electrode lug;

[0083] A third providing device is used to provide a housing having an opening;

[0084] A first assembly device is used to install the electrode assembly and current collector into the housing, and to position the first tab at the end of the electrode assembly facing the opening.

[0085] The fourth providing device is used to provide an end cap and close the end cap to the opening so that the electrode assembly is sealed in the housing and the current collector is disposed between the end cap and the first electrode tab;

[0086] The second assembly device is used to weld the end cap and current collector to achieve electrical connection between the end cap and the first electrode tab. Attached Figure Description

[0087] 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.

[0088] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0089] Figure 2 Explosion diagrams of batteries provided for some embodiments of this application;

[0090] Figure 3 for Figure 2 An exploded view of the battery module shown.

[0091] Figure 4 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application;

[0092] Figure 5 A cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0093] Figure 6 for Figure 5 An enlarged schematic diagram of the battery cell shown at box A;

[0094] Figure 7 This is an assembly diagram of the current collector and electrode assembly of a battery cell provided in some embodiments of this application;

[0095] Figure 8 for Figure 7 The diagram shows the structure of the electrode assembly.

[0096] Figure 9 A cross-sectional view of a battery cell provided for some embodiments of the present application;

[0097] Figure 10 A cross-sectional view of a battery cell provided for some embodiments of the present application;

[0098] Figure 11 A cross-sectional view of a battery cell provided for some embodiments of the present application; Figure 10 An enlarged view of the battery cell shown at circle B;

[0099] Figure 12 A cross-sectional view of a battery cell provided for some embodiments of the present application;

[0100] Figure 13 An enlarged view of the battery cell shown at circle C; Figure 12 An enlarged view of the battery cell shown at circle C;

[0101] Figure 14 A flowchart of a manufacturing method of a battery cell provided for some embodiments of the present application;

[0102] Figure 15 A schematic block diagram of a manufacturing system of a battery cell provided for some embodiments of the present application.

[0103] In the drawings, the drawings are not drawn according to the actual proportions. DETAILED DESCRIPTION

[0104] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0105] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the specification, claims and above description of drawings of the present application, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. The specification, claims and above description of drawings of the present application, the terms "first", "second" and the like are used to distinguish different objects, not to describe a particular order or primary and secondary relationship.

[0106] Reference to "an embodiment" or "the embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" or "in the embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another.

[0107] In the description of the application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "attachment" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0108] The term "and / or" in this application is only to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. In addition, the character " / " in this application generally represents that the front and rear associated objects have an "or" relationship.

[0109] In the embodiments of the application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the application shown in the drawings, and the overall thickness, length and width of the integrated device are only exemplary and should not constitute any limitation on the application.

[0110] "Multiple" appearing in this application means two or more (including two).

[0111] In this application, the battery cell can include a lithium ion secondary battery cell, a lithium ion primary battery cell, a lithium-sulfur battery cell, a sodium lithium ion battery cell, a sodium ion battery cell, or a magnesium ion battery cell, etc. The embodiments of the application are not limited thereto. The battery cell can be in the shape of a cylinder, a flat body, a cuboid, or other shapes, etc. The embodiments of the application are also not limited thereto.

[0112] The battery referred to in the embodiments of the application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application can include a battery module or a battery pack, etc. The battery generally includes a box for packaging one or more battery cells. The box can avoid the influence of liquid or other foreign matters on the charging or discharging of the battery cell.

[0113] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode tab, a negative electrode tab, and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode tab and the negative electrode tab to work. The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer coated on the surface of the positive electrode current collector; the positive electrode current collector includes a positive electrode current collection area and a positive electrode tab protruding from the positive electrode current collection area, and the positive electrode current collection area is coated with the positive electrode active material layer, and at least part of the positive electrode tab is not coated with the positive electrode active material layer. Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material layer includes a positive electrode active material, which can be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate, etc. The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector; the negative electrode current collector includes a negative electrode current collection area and a negative electrode tab protruding from the negative electrode current collection area, and the negative electrode current collection area is coated with the negative electrode active material layer, and at least part of the negative electrode tab is not coated with the negative electrode active material layer. The material of the negative electrode current collector can be copper, and the negative electrode active material layer includes a negative electrode active material, which can be carbon or silicon, etc. The material of the separator can be PP (polypropylene) or PE (polyethylene), etc.

[0114] The battery cell further includes a shell and an end cover. The shell has an opening and is used to accommodate the electrode assembly, and the electrode assembly can be assembled into the shell through the opening of the shell. The end cover is used to cover the opening of the shell to achieve sealing.

[0115] The inventor attempts to electrically connect the end cover to the tab of the electrode assembly to facilitate the extraction of the current of the electrode assembly. In order to achieve the electrical connection between the end cover and the tab, the inventor welds the end cover to the tab. However, the inventor finds that the end surface of the tab abutting against the end cover is uneven, and it is difficult to tightly fit with the end cover. After welding the end cover and the tab, the end cover may produce micro-cracks, which may cause the risk of sealing failure of the end cover and cause safety hazards.

[0116] In view of this, the embodiments of the present application provide a technical scheme. A current collection member is arranged in the battery cell, and the current collection member is welded with the end cover and the tab respectively to achieve the electrical connection between the end cover and the tab. The current collection member can tightly fit with the end cover to reduce the risk of micro-cracks of the end cover, improve the sealing performance, and reduce safety hazards. When the current collection member is welded with the tab, even if the current collection member produces micro-cracks, it will not affect the sealing performance of the battery cell.

[0117] The technical scheme described in the embodiments of the present application is applicable to batteries and electric devices using batteries.

[0118] The electric device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, and an electric tool, etc. The vehicle can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, etc. The spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft, etc. The electric toy includes a fixed or mobile electric toy, such as a game machine, an electric automobile toy, an electric ship toy, and an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, and an electric planer, etc. The electric device is not specially limited in the embodiments of the present application.

[0119] The following embodiments take the vehicle as an example for convenience of description.

[0120] Figure 1 A structural schematic diagram of the vehicle is provided for some embodiments of the present application. As shown in the figure, the vehicle 1 is internally provided with a battery 2, which can be arranged at the bottom, the head, or the tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as an operating power supply of the vehicle 1. Figure 1

[0121] The vehicle 1 can further include a controller 3 and a motor 4, and the controller 3 is used to control the battery 2 to supply power to the motor 4, for example, to meet the working power demand of the vehicle 1 during starting, navigation, and driving.

[0122] In some embodiments of the present application, the battery 2 can not only be used as an operating power supply of the vehicle 1, but also be used as a driving power supply of the vehicle 1, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1.

[0123] Figure 2 An explosion schematic diagram of the battery is provided for some embodiments of the present application. As shown in the figure, the battery 2 includes a box body 5 and a battery monomer (not shown), and the battery monomer is contained in the box body 5. Figure 2 Figure 2

[0124] ​​​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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Figure 3 for Figure 2 The diagram shows an exploded view of the battery module.

[0129] 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.

[0130] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6.

[0131] Figure 4 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application; Figure 5A cross-sectional schematic diagram of a battery cell provided in some embodiments of this application; Figure 6 for Figure 5 An enlarged schematic diagram of the battery cell shown at box A; Figure 7 This is an assembly diagram of the current collector and electrode assembly of a battery cell provided in some embodiments of this application; Figure 8 for Figure 7 The diagram shows the structure of the electrode assembly.

[0132] like Figure 4 to Figure 8 As shown, the battery cell 7 of this application embodiment includes: a housing 20 having an opening 21; an electrode assembly 10 housed within the housing 20, the electrode assembly 10 having a first tab 12 at one end facing the opening 21; an end cap 30 for covering the opening 21 to seal the electrode assembly 10 within the housing 20; and a current collector 50 disposed between the end cap 30 and the first tab 12, the current collector 50 being configured to be welded to the end cap 30 and the first tab 12 respectively to achieve an electrical connection between the end cap 30 and the first tab 12.

[0133] The electrode assembly 10 includes a first electrode, a second electrode, and a separator, the separator being used to separate the first electrode and the second electrode. The first electrode and the second electrode have opposite polarities; in other words, one of the first electrode and the second electrode is the positive electrode, and the other of the first electrode and the second electrode is the negative electrode.

[0134] Optionally, the first electrode, the second electrode, and the separator are all strip structures, and the first electrode, the second electrode, and the separator are wound together to form a wound structure. The wound structure can be a cylindrical structure, a flat structure, or other shapes.

[0135] From the external appearance of the electrode assembly 10, the electrode assembly 10 includes a main body 11, a first electrode tab 12, and a second electrode tab 13, which are connected to the main body 11. The first electrode tab 12 is the portion of the first electrode sheet that is not coated with an active material layer, and the second electrode tab 13 is the portion of the second electrode sheet that is not coated with an active material layer. Correspondingly, one of the first electrode tab 12 and the second electrode tab 13 is a positive electrode tab, and the other is a negative electrode tab.

[0136] The first tab 12 and the second tab 13 are respectively disposed on both sides of the main body 11. In other words, the first tab 12 and the second tab 13 are respectively disposed at both ends of the electrode assembly 10. Optionally, the first tab 12 is located at the end of the electrode assembly 10 facing the end cover 30, and the second tab 13 is located at the end of the electrode assembly 10 away from the end cover 30.

[0137] The first tab 12 is wound around a central axis X of the electrode assembly 10, and the first tab 12 is generally cylindrical. The first tab 12 includes N layer structures 121 arranged around the central axis X, N being a positive integer greater than 1.

[0138] The first tab 12 has an inner end 12a and an outer end 12b at two ends along a winding direction Y, and the layer structures 121 are divided based on the inner end 12a of the first tab 12 in the embodiment.

[0139] Specifically, the inner end 12a of the first tab 12 is a leading end of a first layer structure 121, a trailing end of the first layer structure 121 is aligned with the leading end of the first layer structure 121 in a radial direction of the first tab 12, and the first layer structure 121 winds around the central axis X once. Correspondingly, the trailing end of the first layer structure 121 is a leading end of a second layer structure 121, and so on. The N layer structures 121 are connected end to end along the winding direction Y. When the layer structures 121 are divided, the leading end of each layer structure 121 is aligned with the inner end 12a of the first tab 12 in the radial direction of the first tab 12. The radial direction of the first tab 12 is perpendicular to the central axis X and passes through the central axis X.

[0140] For example, the inner end 12a and the outer end 12b of the first tab 12 are aligned in the radial direction of the first tab 12, so that each layer structure 121 winds around the central axis X once.

[0141] Of course, alternatively, the inner end 12a and the outer end 12b of the first tab 12 can also not be aligned in the radial direction of the first tab 12, so that the last layer structure 121 winds around the central axis X less than once, for example, the last layer structure 121 can wind around the central axis X 1 / 4 times, 1 / 3 times, 1 / 2 times, 2 / 3 times, or 3 / 4 times.

[0142] After winding is completed, the first tab 12 is generally cylindrical, and a gap is left between adjacent two layer structures 121. The first tab 12 can be processed in the embodiment to reduce the gap between the layer structures 121, so as to facilitate connection of the first tab 12 with the current collecting member 50. For example, the first tab 12 can be subjected to a flattening treatment in the embodiment, so that an end region of the first tab 12 away from the main body part 11 is gathered together; the flattening treatment forms a dense end face at one end of the first tab 12 away from the main body part 11, reduces the gap between the layer structures 121, and facilitates connection of the first tab 12 with the current collecting member 50. Alternatively, the embodiment can also fill a conductive material between adjacent two layer structures 121 to reduce the gap between the layer structures 121.

[0143] Optionally, the second tab 13 is wound around the central axis X of the electrode assembly 10 in multiple turns, and the second tab 13 includes multiple layer structures. Exemplarily, the second tab 13 is also subjected to a rubbing process to reduce the gap between the layer structures of the second tab 13.

[0144] The shell 20 is a hollow structure with one side open, and the end cover 30 is connected to the opening 21 of the shell 20 to form a sealed connection, thereby forming a containing cavity for containing the electrode assembly 10 and the electrolyte.

[0145] The shell 20 is a hollow structure, and the inside of the shell 20 forms a space for containing the electrode assembly 10. The shell 20 can have various shapes, such as a cylinder, a cuboid, etc. The shape of the shell 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cylindrical structure, a cylindrical shell can be selected; if the electrode assembly 10 is a cuboid structure, a cuboid shell can be selected.

[0146] The shell 20 includes a side wall 22 and a bottom wall 23. The side wall 22 surrounds the outside of the electrode assembly 10, and the bottom wall 23 is connected to one end of the side wall 22. The side wall 22 is a cylindrical structure, for example, the side wall 22 can be a circular cylinder or a square cylinder; the bottom wall 23 is a plate structure, and the shape of the bottom wall 23 corresponds to the shape of the side wall 22. Optionally, one end of the side wall 22 forms an opening 21, and the bottom wall 23 is connected to the end of the side wall 22 away from the opening 21.

[0147] The side wall 22 and the bottom wall 23 can be an integrally formed structure, that is, the shell 20 is an integrally formed member. Of course, the side wall 22 and the bottom wall 23 can also be two members provided separately and then connected together by welding, riveting, bonding, etc.

[0148] The shell 20 can be positively charged, negatively charged, or not charged. When the shell 20 needs to be charged, the shell 20 can be directly connected to the tab of the electrode assembly 10, or can be electrically connected to the tab through other conductive members.

[0149] The end cover 30 and the shell 20 can be connected by welding, so that the end cover 30 and the shell 20 can have the same polarity. Exemplarily, when the shell 20 needs to be positively charged, the shell 20 can be electrically connected to the positive tab by using the end cover 30; when the shell 20 needs to be negatively charged, the shell 20 can be electrically connected to the negative tab by using the end cover 30. Of course, the shell 20 can also be connected to the tab through other conductive structures, which is not limited in the present embodiment.

[0150] The shell 20 and the end cover 30 can be made of the same material or different materials.

[0151] The current collecting member 50 can conduct the end cover 30 and the first tab 12, and make the polarities of the end cover 30 and the first tab 12 the same. Optionally, the current collecting member 50 is a plate-shaped structure made of a metal material.

[0152] In assembling the battery cell 7, the current collecting member 50 is welded with the first tab 12 first. For example, the current collecting member 50 can be pressed against the first tab 12 first, and then a laser is irradiated on the surface of the current collecting member 50 away from the first tab 12, which melts and connects a part of the current collecting member 50 and a part of the first tab 12.

[0153] After the electrode assembly 10 and the current collecting member 50 are installed into the housing 20, the end cover 30 is then covered on the opening 21 of the housing 20 and welded with the current collecting member 50. For example, a laser is irradiated on the surface of the end cover 30 away from the current collecting member 50, which melts and connects a part of the end cover 30 and a part of the current collecting member 50.

[0154] At least a part of the current collecting member 50 abuts against and closely adheres to the end cover 30, so as to facilitate the welding of the current collecting member 50 and the end cover 30. Optionally, the surface of the current collecting member 50 abutting against the end cover 30 is a plane.

[0155] The current collecting member 50 is a separately formed member, which is different from the first tab 12 formed by winding. The shape of the current collecting member 50 can be adaptively adjusted according to the shape of the end cover 30, so as to ensure that the current collecting member 50 can closely adhere to the end cover 30.

[0156] In the embodiment, the current collecting member 50 is welded with the end cover 30 and the first tab 12 respectively, so as to realize the electrical connection of the end cover 30 and the first tab 12. The current collecting member 50 can closely adhere to the end cover 30, so as to reduce the risk of micro-cracks of the end cover 30, improve the sealing performance, reduce the safety hazard, and improve the safety. When the current collecting member 50 is welded with the first tab 12, even if the current collecting member 50 generates micro-cracks, the sealing performance of the battery cell 7 will not be affected.

[0157] In some embodiments, the end cover 30 is used to electrically connect the first tab 12 and the housing 20.

[0158] In the embodiment, the housing 20 itself can serve as the output pole of the battery cell 7, so that a traditional electrode terminal is omitted, and the structure of the battery cell 7 is simplified. When a plurality of battery cells 7 are assembled into a group, the housing 20 can be electrically connected with a busbar, so that the overcurrent area is increased, and the structure design of the busbar is more flexible.

[0159] In some embodiments, the housing 20 is welded with the end cover 30. The welding can realize the connection of the housing 20 and the end cover 30, improve the overcurrent capacity between the housing 20 and the end cover 30, and ensure the sealing performance.

[0160] In some embodiments, the shell 20 further comprises a side wall 22 extending along the thickness direction Z of the end cover 30 and surrounding the outer periphery of the electrode assembly 10, and a bottom wall 23 connected to the side wall 22, the bottom wall 23 being provided with an electrode lead-out hole 231. The electrode assembly 10 further comprises a second tab 13, the first tab 12 and the second tab 13 being opposite in polarity and respectively located at two ends of the electrode assembly 10. The battery cell 7 further comprises an electrode terminal 40 mounted to the electrode lead-out hole 231, the electrode terminal 40 being electrically connected to the second tab 13.

[0161] The second tab 13 can be directly electrically connected to the electrode terminal 40, or indirectly electrically connected to the electrode terminal 40 through other conductive structures.

[0162] The electrode terminal 40 is insulatively arranged on the bottom wall 23, the electrode terminal 40 and the bottom wall 23 can have different polarities, and the electrode terminal 40 and the bottom wall 23 can respectively serve as two output poles of the battery cell 7.

[0163] When the first tab 12 is a negative tab and the second tab 13 is a positive tab, the bottom wall 23 serves as a negative output pole of the battery cell 7, and the electrode terminal 40 serves as a positive output pole of the battery cell 7. When the first tab 12 is a positive tab and the second tab 13 is a negative tab, the bottom wall 23 serves as a positive output pole of the battery cell 7, and the electrode terminal 40 serves as a negative output pole of the battery cell 7.

[0164] The electrode terminal 40 is fixed to the bottom wall 23. The electrode terminal 40 can be fixed to the outside of the bottom wall 23 as a whole, or can extend into the interior of the shell 20 through the electrode lead-out hole 231.

[0165] The first tab 12 is located at one end of the electrode assembly 10 facing the end cover 30, so as to facilitate the electrical connection between the end cover 30 and the first tab 12; correspondingly, the second tab 13 is located at one end of the electrode assembly 10 facing the bottom wall 23, so as to facilitate the electrical connection between the electrode terminal 40 and the second tab 13. The embodiments of the present application arrange the first tab 12 and the second tab 13 at two ends of the electrode assembly 10, which can reduce the risk of conduction of the first tab 12 and the second tab 13, and increase the overcurrent area of the first tab 12 and the overcurrent area of the second tab 13.

[0166] In the embodiments, the bottom wall 23 and the electrode terminal 40 can serve as two output poles of the battery cell 7, which can simplify the structure of the battery cell 7 and ensure the overcurrent capacity of the battery cell 7. The bottom wall 23 and the electrode terminal 40 are located at the same end of the battery cell 7, so that when a plurality of battery cells 7 are assembled into a group, the current collecting component can be assembled to the same side of the battery cell 7, which can simplify the assembly process and improve the assembly efficiency.

[0167] In some embodiments, the bottom wall 23 and the side wall 22 are integrally formed. This embodiment can omit the connecting process of the bottom wall 23 and the side wall 22. The shell 20 can be formed by a stretching process.

[0168] The electrode lead-out hole 231 of the embodiment of the application is made after the shell 20 is formed by the stretching process.

[0169] The inventors have tried to roll the open end of the shell to make the open end of the shell fold inward and form a flange structure, which presses the end cover to achieve the fixation of the end cover. The inventors install the electrode terminal on the end cover and take the flange structure and the electrode terminal as two output poles of the battery monomer. However, the larger the size of the flange structure is, the higher the risk of curling and wrinkling of the flange structure after forming is. If the flange structure is curled and wrinkled, the surface of the flange structure is uneven, and when the flange structure is welded with the busbar component, the welding is poor. Therefore, the size of the flange structure is limited, which causes the insufficient overcurrent capacity of the battery monomer.

[0170] The embodiment of the application forms the electrode lead-out hole 231 for installing the electrode terminal 40 on the bottom wall 23 by the opening process to set the positive output pole and the negative output pole at one end of the battery monomer 7 away from the opening 21. The bottom wall 23 is formed during the forming process of the shell 20, and the flatness of the bottom wall 23 can be ensured after the electrode lead-out hole 231 is opened, and the connection strength of the bottom wall 23 and the busbar component is ensured. At the same time, the flatness of the bottom wall 23 is not restricted by the size of the bottom wall 23 itself, so the bottom wall 23 can have a larger size, thereby improving the overcurrent capacity of the battery monomer 7.

[0171] In some embodiments, the first tab 12 is a negative electrode tab, and the base material of the shell 20 is steel.

[0172] The shell 20 is electrically connected with the negative electrode tab, that is, the shell 20 is in a low potential state. The steel shell 20 is not easy to be corroded by the electrolyte in the low potential state, so as to reduce the safety risk.

[0173] In some embodiments, the base material of the shell 20 and the base material of the end cover 30 are the same. Alternatively, the base material of the shell 20 and the base material of the end cover 30 are both steel.

[0174] In the embodiment, the base material of the shell 20 and the base material of the end cover 30 are the same, which can ensure the welding strength of the shell 20 and the end cover 30 and the sealing of the battery monomer 7.

[0175] In some embodiments, the battery monomer 7 is a cylindrical battery monomer. Correspondingly, the electrode assembly 10 is a cylindrical structure, and the shell 20 is a cylindrical hollow structure.

[0176] In some embodiments, a portion of the current collecting member 50 is brought into abutment with the end cap 30 and is welded to form a first weld W1, and another portion of the current collecting member 50 is brought into abutment with the first tab 12 and is welded to form a second weld W2. The projection of the first weld W1 along the thickness direction Z of the end cap 30 and the projection of the second weld W2 along the thickness direction Z of the end cap 30 do not overlap.

[0177] The present embodiment welds two different portions of the current collecting member 50 to the end cap 30 and the first tab 12, respectively, so that the projection of the first weld W1 along the thickness direction Z of the end cap 30 and the projection of the second weld W2 along the thickness direction Z of the end cap 30 do not overlap.

[0178] The first weld W1 and the second weld W2 are structures formed after a process of melting, cooling and solidification, etc. of the material, and the surfaces of the two are uneven.

[0179] When assembling the battery cell 7, the current collecting member 50 is first brought into abutment with the first tab 12 and is welded to form the second weld W2, and then the end cap 30 and the current collecting member 50 are welded to form the first weld W1. If the projection of the first weld W1 along the thickness direction Z of the end cap 30 and the projection of the second weld W2 along the thickness direction Z of the end cap 30 overlap, then when the end cap 30 and the current collecting member 50 are welded, the portion of the end cap 30 used for welding with the current collecting member 50 needs to be brought into abutment on the second weld W2. Since the surface of the second weld W2 is uneven, if the portion of the end cap 30 used for welding with the current collecting member 50 is brought into abutment on the second weld W2, then the end cap 30 is difficult to closely fit with the second weld W2, which can cause poor welding, affect the connection strength of the end cap 30 and the current collecting member 50, and cause the risk of micro-cracks being formed in the end cap 30.

[0180] In the present embodiment, the projection of the first weld W1 along the thickness direction Z of the end cap 30 and the projection of the second weld W2 along the thickness direction Z of the end cap 30 do not overlap, which can improve the welding reliability of the end cap 30 and the current collecting member 50 when the end cap 30 and the current collecting member 50 are welded without being affected by the second weld W2.

[0181] In some embodiments, the electrode assembly 10 is wound along the central axis X and forms a first tab 12, the first tab 12 comprising N layer structures 121 arranged around the central axis X, the extension direction of the central axis X being parallel to the thickness direction Z of the end cover 30. The first tab 12 is composed of a first annular portion 122 and a second annular portion 123 arranged outside the first annular portion 122, the number of layer structures 121 in the first annular portion 122 being N1, the number of layer structures 121 in the second annular portion 123 being N2, N=N1+N2, the value of |N1-N2| being less than or equal to 2, N1 and N2 being positive integers. The first annular portion 122 is welded to the current collecting member 50 and forms a first part W21, the second annular portion 123 is welded to the current collecting member 50 and forms a second part W22 connected to the first part W21, the second welding portion W2 being composed of the first part W21 and the second part W22.

[0182] Each layer structure 121 in the first annular portion 122 surrounds the central axis X once. The junction of the first annular portion 122 and the second annular portion 123 is radially aligned with the inner end 12a of the first tab 12.

[0183] The electrons in the region of the electrode assembly 10 corresponding to the first annular portion 122 can move along a first current path formed by the first annular portion 122, the first part W21, the current collecting member 50, the first welding portion W1 and the end cover 30, the electrons in the region of the electrode assembly 10 corresponding to the second annular portion 123 can move along a second current path formed by the second annular portion 123, the second part W22, the current collecting member 50, the first welding portion W1 and the end cover 30, and the boundary between the first annular portion 122 and the second annular portion 123 is located approximately in the middle region of the first tab in the radial direction.

[0184] In the present embodiment, the boundary between the first annular portion 122 and the second annular portion 123 is located approximately in the middle region of the first tab 12 in the radial direction, and some layer structures 121 in the middle region of the first tab 12 are welded to the current collecting member 50 and form part of the second welding portion W2, which can reduce the difference between the first current path and the second current path to some extent, improve the uniformity of the current density, reduce the internal resistance and improve the overcurrent capacity.

[0185] In some embodiments, N3 consecutive layer structures 121 in the first annular portion 122 arranged close to the second annular portion 123 are welded to the current collecting member 50 and form the first part W21, N4 consecutive layer structures 121 in the second annular portion 123 arranged close to the first annular portion 122 are welded to the current collecting member 50 and form the second part W22, the N3 consecutive layer structures 121 and the N4 consecutive layer structures 121 are arranged continuously, N4>N3≥1, N3 and N4 being positive integers.

[0186] Since the second annular portion 123 is arranged outside the first annular portion 122, the circumference of the layer structure 121 in the second annular portion 123 is greater than the circumference of the layer structure 121 in the first annular portion 122, and the path of the electrons in the electrode assembly 10 corresponding to the second annular portion 123 is longer between the layer structures 121 in the second annular portion 123. In the embodiment, N4>N3, so that the layer structure 121 connected to the second portion W22 can be increased, the transmission of the electrons between the layer structures 121 in the second annular portion 123 can be reduced, the second current path can be shortened, the difference between the first current path and the second current path can be further reduced, the uniformity of the current density can be improved, the internal resistance can be reduced, and the overcurrent capacity can be improved.

[0187] In some embodiments, M consecutive layer structures 121 in all the layer structures 121 are welded to the current collecting member 50 and form the second welding portion W2, where 1 / 3≤M / N≤1 / 2, M≥2, and M is a positive integer.

[0188] Optionally, M=N3+N4.

[0189] The greater the value of M / N is, the smaller the internal resistance of the first tab 12 is, the greater the area of the second welding portion W2 is, and the stronger the overcurrent capacity between the first tab 12 and the current collecting member 50 is. However, when the area of the current collecting member 50 is constant, the greater the value of M / N is, the smaller the area of the first welding portion W1 is, and the lower the overcurrent capacity between the current collecting member 50 and the end cover 30 is.

[0190] The inventor limits the value of M / N to 1 / 3-1 / 2 through experiments, so as to balance the overcurrent capacity between the first tab 12 and the current collecting member 50 and the overcurrent capacity between the current collecting member 50 and the end cover 30, and optimize the overcurrent capacity of the battery monomer 7.

[0191] In some embodiments, the second welding portion W2 is a plurality of second welding portions W2, and the plurality of second welding portions W2 are arranged at intervals along the circumference of the first tab 12. Of course, the application is not limited thereto, and in other embodiments, the second welding portion W2 can also be one, for example, the second welding portion W2 can be annular, spiral, or linear.

[0192] In some embodiments, the end cover 30 includes a cover body 31 and a first protrusion 32 protruding from the inner surface 311 of the cover body in a direction facing the first tab 12.

[0193] The cover body 31 is a plate-shaped structure having an inner surface and an outer surface oppositely arranged along the thickness direction Z, and the inner surface 311 of the cover body faces the electrode assembly 10. Optionally, the inner surface 311 of the cover body and the outer surface 312 of the cover body are both planes and are arranged in parallel.

[0194] The first protrusion 32 protrudes in a direction facing the electrode assembly 10 relative to the inner surface 311 of the cover body, such that at least a portion of the first protrusion 32 protrudes from the inner surface 311 of the cover body. The present embodiment does not limit the degree to which the first protrusion 32 protrudes from the inner surface 311 of the cover body.

[0195] The first protrusion 32 is connected to the cover body 31. Illustratively, the first protrusion 32 is in the form of a ring structure surrounding the outside of the cover body 31. Of course, alternatively, the cover body 31 can also surround the outside of the first protrusion 32.

[0196] The current collector member 50 can be welded to the first protrusion 32 or to the cover body 31, and the present embodiment does not limit this.

[0197] In some embodiments, the end cover 30 includes the cover body 31 and the first protrusion 32 protruding in a direction facing the first tab 12 from the inner surface 311 of the cover body, the first protrusion 32 being configured to abut and be welded to the current collector member 50 to form a first welding portion W1 and form a first avoidance gap G1 between the current collector member 50 and the cover body 31 for avoiding the second welding portion W2.

[0198] The top end surface of the first protrusion 32 abuts and supports the current collector member 50 to at least separate the cover body 31 and the current collector member 50 in the thickness direction Z.

[0199] The projection of the second welding portion W2 in the thickness direction Z at least partially overlaps the projection of the cover body 31 in the thickness direction Z. Alternatively, the projection of the second welding portion W2 in the thickness direction Z is located within the projection of the cover body 31 in the thickness direction Z.

[0200] In the present embodiment, by providing the first avoidance gap G1 for avoiding the second welding portion W2, the risk of the second welding portion W2 pressing the cover body 31 is reduced. If the second welding portion W2 abuts the cover body 31, over-positioning will occur between the end cover 30 and the current collector member 50, causing the second welding portion W2 to interfere with the abutment of the first protrusion 32 and the current collector member 50. By providing the first avoidance gap G1, the present embodiment can avoid the interference of the second welding portion W2 with the abutment of the first protrusion 32 and the current collector member 50, and ensure the connection strength of the first protrusion 32 and the current collector member 50.

[0201] In some embodiments, the end cover 30 has a first recess 33 formed at a position corresponding to the first protrusion 32, the first recess 33 being recessed in a direction facing the electrode assembly 10 from the outer surface 312 of the cover body.

[0202] When assembling the end cover 30 and the current collecting member 50, the laser can be applied to the bottom surface of the first recess 33 to weld the first protrusion 32 and the current collecting member 50 from the outside. The present embodiment reduces the thickness of the first protrusion 32 by providing the first recess 33, so that the welding power required for welding the first protrusion 32 and the current collecting member 50 can be reduced, heat generation can be reduced, and the risk of burning other components can be reduced.

[0203] The first protrusion 32 is a solid structure with a certain thickness; for example, the first protrusion 32 is a thin-walled structure. The first recess 33 is a cavity without a solid structure.

[0204] The first recess 33 can reduce the strength of the first protrusion 32 and improve the elastic deformation capability of the first protrusion 32, so that the first protrusion 32 can release stress by deformation and reduce the impact force during the process of pressing the first protrusion 32 against the current collecting member 50, thereby reducing the risk of damaging the current collecting member 50 and the first tab 12.

[0205] In some embodiments, the bottom surface of the first recess 33 is closer to the first tab 12 than the inner surface 311 of the cover body.

[0206] The first recess 33 and the first protrusion 32 can be formed by stamping the end cover 30. The greater the depth of the first recess 33 in the thickness direction Z, the greater the degree to which the first protrusion 32 protrudes from the inner surface 311 of the cover body, and the greater the first clearance gap G1.

[0207] The present embodiment can ensure the degree to which the first protrusion 32 protrudes from the inner surface 311 of the cover body, so as to more effectively support the current collecting member 50 and reduce the risk of the second welding portion W2 contacting the end cover 30. Meanwhile, the present embodiment further ensures the degree to which the first recess 33 is recessed under the premise of ensuring the protruding degree of the first protrusion 32, so as to improve the elastic deformation capability of the first protrusion 32 and reduce the risk of damaging the current collecting member 50 and the first tab 12 during assembly.

[0208] In some embodiments, the cover body 31 surrounds the outside of the first protrusion 32, and the first welding portion W1 is located inside the second welding portion W2.

[0209] In the present embodiment, the inside and the outside are positions relative to the central axis X. The first protrusion 32 is closer to the central axis X than the cover body 31, and the first welding portion W1 is closer to the central axis X than the second welding portion W2.

[0210] In some embodiments, a first recess 33 is formed on the end cover 30 at a position corresponding to the first protrusion 32, and the first recess 33 is recessed from the outer surface 312 of the cover body in a direction facing the electrode assembly 10. The bottom surface of the first recess 33 is provided with a groove 34, and the bottom of the groove 34 is used for welding with the current collecting member 50 and forms a first welding portion W1.

[0211] The groove 34 is recessed from the bottom surface of the first recess 33 in a direction facing the electrode assembly 10. The portion of the first protrusion 32 between the bottom surface of the groove 34 and the top end surface of the first protrusion 32 forms a connecting portion, which is used for welding with the current collecting member 50 and forms the first welding portion W1.

[0212] The present embodiment reduces the thickness of the connecting portion of the first protrusion 32 by providing the first recess 33 and the groove 34, which can reduce the welding power required for welding the connecting portion with the current collecting member 50, reduce heat generation, and reduce the risk of burning other components (such as the separator).

[0213] In some embodiments, the end cover 30 further comprises a second protrusion 35 surrounding the outer side of the cover body 31, and the second protrusion 35 protrudes from the inner surface 311 of the cover body in a direction facing the first tab 12, and the second protrusion 35 is used to support the first tab 12.

[0214] The second protrusion 35 is an annular structure surrounding the outer side of the cover body 31. In the radial direction, the second protrusion 35 is closer to the side wall 22 than the cover body 31.

[0215] The second protrusion 35 can directly support the first tab 12, or can support the first tab 12 through other components (such as the current collecting member 50).

[0216] In the present embodiment, the second protrusion 35 can support the first tab 12 to reduce the shaking amplitude of the electrode assembly 10 when the battery cell 7 is shaken, and improve the stability of the electrode assembly 10.

[0217] In some embodiments, the second protrusion 35 directly abuts and supports the first tab 12.

[0218] In some embodiments, the second protrusion 35 is spaced apart from the current collecting member 50 to avoid interference between the second protrusion 35 and the abutment of the current collecting member 50 and the first protrusion 32, and to ensure that the first protrusion 32 is tightly attached to the current collecting member 50.

[0219] Optionally, the second protrusion 35 surrounds the outer side of the current collecting member 50.

[0220] In some embodiments, the outer side surface 351 of the second protrusion abuts the inner surface of the shell 20 and is used for welding with the shell 20 to seal the opening 21.

[0221] The outer side surface 351 of the second protrusion 35 is a surface of the second protrusion 35 facing the side wall 22 of the housing 20. The outer side surface 351 of the second protrusion 35 is a cylindrical surface, and optionally, the outer side surface 351 of the second protrusion 35 is a circular cylindrical surface.

[0222] The portion of the second protrusion 35 extending into the housing 20 can be interference fit, transition fit or clearance fit with the housing 20. Optionally, the portion of the second protrusion 35 extending into the housing 20 can be interference fit with the housing 20, which can increase the connection strength between the housing 20 and the end cover 30 and improve the sealing performance.

[0223] Optionally, the second protrusion 35 and the side wall 22 of the housing 20 are connected by laser welding. During welding, the laser is irradiated at the junction of the second protrusion 35 and the side wall 22, and the laser melts and connects at least part of the outer side surface 351 of the second protrusion 35 and part of the inner surface of the housing 20. The outer side surface 351 of the second protrusion abuts against the inner surface of the housing 20, which can reduce the risk of the laser burning the electrode assembly 10 inside the housing 20.

[0224] Alternatively, the laser can also be irradiated at the outer surface of the side wall 22 away from the second protrusion 35.

[0225] In the present embodiment, the welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and overcurrent capacity between the second protrusion 35 and the housing 20.

[0226] In some embodiments, a second recess 36 is formed on the end cover 30 at a position corresponding to the second protrusion 35, and the second recess 36 is recessed from the outer surface 312 of the cover body in a direction facing the electrode assembly 10.

[0227] The second recess 36 can reduce the strength of the second protrusion 35 and improve the elasticity of the second protrusion 35, so that the second protrusion 35 can release welding stress by deformation during welding of the second protrusion 35 and the housing 20, thereby reducing the risk of deformation and cracking of the welding area and improving the sealing performance.

[0228] In some embodiments, the bottom surface of the second recess 36 is closer to the first tab 12 than the inner surface 311 of the cover body.

[0229] The second recess 36 and the second protrusion 35 can be formed by stamping the end cover 30. The greater the depth of the second recess 36 in the thickness direction Z, the greater the degree of protrusion of the second protrusion 35 from the inner surface 311 of the cover body.

[0230] The second protrusion 35 can protrude to a certain extent of the inner surface 311 of the cover body to support the first tab 12. Meanwhile, the second protrusion 35 can further protrude to a certain extent of the second recess 36 to improve the elasticity of the second protrusion 35, so that the second protrusion 35 can release the welding stress by deforming.

[0231] In some embodiments, the cover body 31 is provided with a weak portion V for breaking when the internal pressure of the battery cell 7 reaches a threshold value, so as to release the internal pressure.

[0232] The threshold value is designed according to different design requirements. The threshold value can depend on the material of one or more of the positive electrode plate, the negative electrode plate, the electrolyte and the separator in the battery cell 7.

[0233] After the weak portion V breaks, a channel is formed for the internal pressure to be released. After the weak portion V breaks, the high-temperature and high-pressure substances in the interior of the battery cell 7 will be discharged outward from the broken portion as the discharge. In this way, the battery cell 7 can be depressurized in a controllable pressure, so as to avoid a potentially more serious accident. The discharge from the battery cell 7 mentioned in the present application includes but is not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of the separator, high-temperature and high-pressure gas generated by reaction, flame, etc.

[0234] The present embodiment improves the safety performance by providing the weak portion V on the cover body 31 to release the internal pressure when the battery cell 7 is in thermal runaway. The present embodiment forms the first avoiding gap G1 between the current collecting member 50 and the cover body 31 to reduce the risk of the current collecting member 50 blocking the exhaust channel when the weak portion V breaks, to ensure smooth exhaust and reduce the safety risk.

[0235] In some embodiments, the current collecting member 50 is in a flat plate structure. The flat plate-shaped current collecting member 50 is easier to form. The flat plate-shaped current collecting member 50 can be in contact with the first tab 12 as a whole, thereby increasing the flow area and making the current collecting member 50 support the first tab 12 more uniformly, reducing the risk of the electrode assembly 10 being offset or misaligned in the thickness direction Z. The flat plate-shaped current collecting member 50 can also be in close contact with the first protrusion 32 to reduce the risk of the first protrusion 32 generating micro-cracks during welding, thereby improving the sealing performance and safety.

[0236] In some embodiments, the first protrusion 32 supports the first tab 12 through the current collecting member 50.

[0237] In the present embodiment, the first protrusion 32 supports the first tab 12 through the current collecting member 50 to reduce the amplitude of the shaking of the electrode assembly 10 when the battery cell 7 is shaken and to improve the stability of the electrode assembly 10. The current collecting member 50 can support the electrode assembly 10 through the first tab 12 to reduce the risk of the shift or misalignment of the electrode assembly 10 in the thickness direction Z.

[0238] The first protrusion 32 supports the middle region of the first tab 12 through the current collecting member 50, and the second protrusion 35 supports the edge region of the first tab 12, which can improve the uniformity of the force received by the first tab 12 and reduce the risk of the shift or misalignment of the electrode assembly 10 in the thickness direction Z.

[0239] Figure 9 A cross-sectional view of a battery cell provided for another embodiment of the present application is shown in FIG. 6. Figure 10 A cross-sectional view of a battery cell provided for another embodiment of the present application is shown in FIG. 6. Figure 11 A cross-sectional view of a battery cell provided for another embodiment of the present application is shown in FIG. 6. Figure 10 An enlarged view of the battery cell shown in FIG. 6 at the circular frame B is shown in FIG. 7.

[0240] As shown in FIG. 6, in some embodiments, the first protrusion 32 is arranged on the outer side of the cover body 31, and the first welding portion W1 is arranged on the outer side of the second welding portion W2. Figure 9

[0241] In the present embodiment, the outer side is a position relative to the central axis X. The cover body 31 is closer to the central axis X than the first protrusion 32, and the second welding portion W2 is closer to the central axis X than the first welding portion W1.

[0242] In some embodiments, the outer side surface 321 of the first protrusion abuts against the inner surface of the shell 20 and is used for welding with the shell 20 to seal the opening.

[0243] The outer side surface 321 of the first protrusion is a surface of the first protrusion 32 facing the side wall 22 of the shell 20. The outer side surface 321 of the first protrusion is a cylindrical surface, which can be a circular cylindrical surface.

[0244] The portion of the first protrusion 32 extending into the shell 20 can be in interference fit, transition fit or clearance fit with the shell 20. Alternatively, the portion of the first protrusion 32 extending into the shell 20 can be in interference fit with the shell 20, which can increase the connection strength between the shell 20 and the end cover 30 and improve the sealing performance.

[0245] ​Optionally, the first protrusion 32 and the sidewall 22 of the housing 20 are connected by laser welding. During welding, the laser irradiates the junction of the first protrusion 32 and the sidewall 22, melting and connecting at least a portion of the outer surface 321 of the first protrusion and a portion of the inner surface of the housing 20. The outer surface 321 of the first protrusion abuts against the inner surface of the housing 20, thus reducing the risk of the laser penetrating the interior of the housing 20 and burning the electrode assembly 10.

[0246] Alternatively, the laser can also be applied to the outer surface of the sidewall 22 that is away from the first protrusion 32.

[0247] In this embodiment, welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and current carrying capacity between the housing 20 and the first protrusion 32.

[0248] like Figure 10 and Figure 11 As shown, in some embodiments, the end cap 30 further includes an extension 37 surrounding the outside of the first protrusion 32, the surface of the extension 37 facing the first tab 12 abutting against and welding the end face 24 of the surrounding opening 21 of the housing 20 to close the opening 21.

[0249] The extension 37 includes an inner surface and an outer surface disposed opposite to each other along the thickness direction Z, and the inner surface of the extension 37 faces the first electrode tab 12. Optionally, the extension 37 is an annular plate structure, and both the inner surface and the outer surface of the extension 37 are planar.

[0250] The extension 37 and the housing 20 are arranged along the thickness direction Z, and the inner surface of the extension 37 can be arranged parallel to the end face 24 of the housing 20.

[0251] Optionally, during welding, the laser irradiates the junction of the end face 24 of the housing 20 and the inner surface of the extension 37; after welding, at least a portion of the inner surface of the extension 37 and at least a portion of the end face 24 of the housing 20 melt and join together.

[0252] In this embodiment, when assembling the end cap 30 and the housing 20, the end face 24 of the housing 20 can play a limiting role in the thickness direction Z, reducing the risk of the end cap 30 being over-inserted into the housing 20 and improving assembly efficiency.

[0253] In some embodiments, the end cap 30 further includes a second protrusion 35, with the cap body 31 surrounding the outer side of the second protrusion 35, the second protrusion 35 protruding from the inner surface 311 of the cap body in a direction facing the first electrode tab 12. A second recess 36 is formed on the end cap 30 at a position corresponding to the second protrusion 35, recessed from the outer surface 312 of the cap body in a direction facing the electrode assembly 10.

[0254] The second protrusion 35 and the second recess 36 can be formed by stamping the end cover 30.

[0255] The battery cell 7 can release a small amount of gas during normal cycling, which can increase the internal pressure of the battery cell 7, thereby causing the risk of deformation of the end cover 30. The present embodiment can increase the strength of the end cover 30 and reduce the deformation of the end cover 30 by providing the second protrusion 35 and the second recess 36 in the middle of the end cover 30.

[0256] In some embodiments, a weakened portion V is provided on the area of the second protrusion 35 opposite to the bottom surface of the second recess 36, and the weakened portion V is used to break when the internal pressure of the battery cell 7 reaches a threshold value, so as to release the internal pressure.

[0257] The present embodiment can improve the safety performance by providing the weakened portion V on the second protrusion 35 to release the internal pressure when the battery cell 7 is in thermal runaway. The weakened portion V is formed on the area of the second protrusion 35 opposite to the bottom surface of the second recess 36, so as to increase the distance between the weakened portion V and other external components, and reduce the risk of the weakened portion V being pressed by the external components.

[0258] In some embodiments, a second avoiding gap G2 is formed between the second protrusion 35 and the current collecting member 50.

[0259] The degree to which the first protrusion 32 protrudes from the inner surface 311 of the cover body is greater than the degree to which the second protrusion 35 protrudes from the inner surface 311 of the cover body, so that the first protrusion 32 can support the current collecting member 50 to form the second avoiding gap G2 between the second protrusion 35 and the current collecting member 50.

[0260] The present embodiment can reduce the risk of the current collecting member 50 blocking the exhaust passage when the weakened portion V breaks, ensure smooth exhaust, and reduce the safety risk by forming the second avoiding gap G2 between the second protrusion 35 and the current collecting member 50.

[0261] Figure 12 A cross-sectional view of a battery cell provided by some other embodiments of the present application is shown in Figure 13 A Figure 12 An enlarged view of the battery cell shown at block C is shown in

[0262] As Figure 12 and Figure 13 In some embodiments, the current collecting member 50 includes a first current collecting portion 51 for abutting and welding with the end cover 30 to form a first welding portion W1, and a second current collecting portion 52 for abutting and welding with the first tab 12 to form a second welding portion W2, the second current collecting portion 52 protrudes from the surface of the first current collecting portion 51 facing the electrode assembly 10, and the second current collecting portion 52 is provided with an avoiding recess 53 on the side away from the electrode assembly 10, and the avoiding recess 53 is used to avoid the second welding portion W2.

[0263] The end cover 30 can be flat or have other shapes.

[0264] In the embodiment, the avoidance recess 53 is arranged to avoid the second welding portion W2, so as to avoid the interference between the second welding portion W2 and the abutment of the first current collecting portion 51 and the end cover 30, ensure the connection strength of the first current collecting portion 51 and the end cover 30, and reduce the risk of the second welding portion W2 crushing the end cover 30. The avoidance recess 53 can reduce the thickness of the second current collecting portion 52, so as to reduce the welding power required for welding the second current collecting portion 52 and the first tab 12, reduce heat generation, and reduce the risk of burning other components (such as a separator).

[0265] In some embodiments, the first current collecting portion 51 is a flat structure surrounding the outside of the second current collecting portion 52.

[0266] In some embodiments, the end cover 30 includes a cover body 31 for welding with the first current collecting portion 51 and forming the first welding portion W1, and a first protrusion 32 surrounding the outside of the cover body 31 and protruding from the inner surface of the cover body in a direction facing the first tab 12, the first protrusion 32 being used to abut the first tab 12 to support the first tab 12.

[0267] In the embodiment, the second current collecting portion 52 supports the middle area of the first tab 12, and the first protrusion 32 supports the edge area of the first tab 12, so as to improve the uniformity of the stress of the first tab 12 and reduce the risk of the electrode assembly 10 being offset or misaligned in the thickness direction Z.

[0268] In some embodiments, a first recess 33 recessed from the outer surface of the cover body in a direction facing the electrode assembly 10 is formed at a position corresponding to the first protrusion 32 on the end cover 30, and the bottom surface of the first recess 33 is closer to the first tab 12 than the inner surface of the cover body.

[0269] The first recess 33 and the first protrusion 32 can be formed by stamping the end cover 30. The greater the depth of the first recess 33 in the thickness direction Z, the greater the degree of the first protrusion 32 protruding from the inner surface of the cover body.

[0270] The embodiment can ensure the degree of the first protrusion 32 protruding from the inner surface of the cover body to support the first tab 12. Meanwhile, the embodiment further ensures the degree of the first recess 33 recessed on the premise of ensuring the degree of the first protrusion 32 protruding, so as to improve the elasticity of the first protrusion 32, reduce the impact force when the first protrusion 32 is pressed against the first tab 12, and reduce the risk of the first tab 12 being crushed.

[0271] In some embodiments, the outer side surface of the first protrusion abuts against the inner surface of the shell 20 and is used for welding with the shell 20 to seal the opening 21.

[0272] The outer side surface of the first protrusion is the surface of the first protrusion 32 facing the side wall 22 of the shell 20. The outer side surface of the first protrusion is a cylindrical surface, optionally, a circular cylindrical surface.

[0273] The portion of the first protrusion 32 extending into the shell 20 can be in interference fit, transition fit or clearance fit with the shell 20. Optionally, the portion of the first protrusion 32 extending into the shell 20 can be in interference fit with the shell 20, which can increase the connection strength between the shell 20 and the end cover 30 and improve the sealing performance.

[0274] Optionally, the first protrusion 32 and the side wall 22 of the shell 20 are connected by laser welding. During welding, the laser is irradiated at the junction of the first protrusion 32 and the side wall 22, and the laser melts and connects at least part of the outer side surface 321 of the first protrusion and part of the inner surface of the shell 20. The outer side surface of the first protrusion abuts against the inner surface of the shell 20, which can reduce the risk of the laser burning the electrode assembly 10 inside the shell 20.

[0275] Alternatively, the laser can also be irradiated at the outer surface of the side wall 22 away from the first protrusion 32.

[0276] In the present embodiment, the welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and overcurrent capacity of the first protrusion 32 and the shell 20.

[0277] In some embodiments, the end cover 30 further comprises a second protrusion 35, and the cover body 31 surrounds the outer side of the second protrusion 35. The second protrusion 35 protrudes from the inner surface 311 of the cover body in a direction facing the first tab 12 and extends into the avoiding recess 53. The end cover 30 forms a second recess 36 corresponding to the second protrusion 35, which is recessed from the outer surface of the cover body in a direction facing the electrode assembly 10.

[0278] The second protrusion 35 and the second recess 36 can be formed by stamping the end cover 30.

[0279] The battery monomer 7 can release a small amount of gas during normal cycling, which can increase the internal pressure of the battery monomer 7 and cause the risk of deformation of the end cover 30. The present embodiment can increase the strength of the end cover 30 and reduce the deformation of the end cover 30 by providing the second protrusion 35 and the second recess 36 in the middle of the end cover 30.

[0280] In some embodiments, the area of the second protrusion 35 opposite to the bottom surface of the second recess 36 is provided with a weakened portion V for breaking when the internal pressure of the battery cell 7 reaches a threshold value to release the internal pressure. The avoiding recess 53 is also used to separate the second current collecting portion 52 from the weakened portion V.

[0281] The present embodiment improves safety performance by providing the weakened portion V on the second protrusion 35 to release the internal pressure when the battery cell 7 is in thermal runaway. The weakened portion V is formed on the second protrusion 35 in the area opposite to the bottom surface of the second recess 36, so that the distance between the weakened portion V and other external components can be increased, and the risk of the weakened portion V being pressed by the external components can be reduced.

[0282] The avoiding recess 53 of the present embodiment can reduce the risk of the current collecting member 50 blocking the exhaust passage when the weakened portion V breaks, ensure smooth exhaust, and reduce the safety risk.

[0283] In some embodiments, the end cover 30 further comprises an extension portion (not shown) surrounding the outer side of the first protrusion, and the surface of the extension portion facing the first tab is abutted and welded with the end surface of the shell surrounding the opening to seal the opening.

[0284] Figure 14 A flowchart of a manufacturing method of a battery cell provided by some embodiments of the present application.

[0285] As shown in Figure 14 , the manufacturing method of a battery cell of the present embodiment comprises:

[0286] S100, providing an electrode assembly, the electrode assembly having a first tab;

[0287] S200, providing a current collecting member, and welding the current collecting member to the first tab;

[0288] S300, providing a shell, the shell having an opening;

[0289] S400, installing the electrode assembly and the current collecting member into the shell, and arranging the first tab at the end of the electrode assembly facing the opening;

[0290] S500, providing an end cover, and covering the end cover on the opening to seal the electrode assembly in the shell, and arrange the current collecting member between the end cover and the first tab;

[0291] S600, welding the end cover and the current collecting member to realize the electrical connection between the end cover and the first tab.

[0292] It should be noted that the related structure of the battery cell manufactured by the above manufacturing method of a battery cell can refer to the battery cell provided by each of the above embodiments.

[0293] When assembling the battery cell based on the above battery cell manufacturing method, the steps do not have to be performed in the order described above, that is, the steps can be performed in the order mentioned in the embodiments, or in an order different from that mentioned in the embodiments, or several steps can be performed simultaneously. For example, steps S100 and S300 can be performed simultaneously.

[0294] Figure 15 A schematic block diagram of a battery cell manufacturing system according to some embodiments of the present application.

[0295] As shown in Figure 15 some embodiments of the present application also provide a battery cell manufacturing system 90, which comprises:

[0296] a first providing device 91 configured to provide an electrode assembly, the electrode assembly having a first tab;

[0297] a second providing device 92 configured to provide a current collecting member and weld the current collecting member to the first tab;

[0298] a third providing device 93 configured to provide a shell, the shell having an opening;

[0299] a first assembling device 94 configured to install the electrode assembly and the current collecting member into the shell, and to position the first tab at an end of the electrode assembly facing the opening;

[0300] a fourth providing device 95 configured to provide an end cover and cover the opening with the end cover, so that the electrode assembly is sealed in the shell and the current collecting member is arranged between the end cover and the first tab;

[0301] a second assembling device 96 configured to weld the end cover and the current collecting member to realize electrical connection between the end cover and the first tab.

[0302] The related structure of the battery cell manufactured by the above manufacturing system can refer to the battery cell provided in the above embodiments.

[0303] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0304] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A single battery cell, comprising: The housing includes a side wall and a bottom wall, the bottom wall and the side wall are integrally formed, one end of the side wall forms an opening, the bottom wall is connected to the end of the side wall opposite to the opening, and the bottom wall is provided with an electrode lead-out hole; An electrode terminal is installed in the electrode lead-out hole, and the electrode terminal is insulated from the bottom wall; An electrode assembly is housed within the housing. The electrode assembly has a wound structure. The sidewalls are arranged around the outer periphery of the electrode assembly. The electrode assembly includes a first electrode tab and a second electrode tab. The first electrode tab and the second electrode tab have opposite polarities. The second electrode tab is located at the end of the electrode assembly facing the bottom wall. The electrode terminal is electrically connected to the second electrode tab. An end cap is provided to close the opening to seal the electrode assembly within the housing. The end cap is electrically connected to the housing, and the first tab is located at the end of the electrode assembly facing the end cap. A current collector is disposed between the end cap and the first electrode tab. The current collector is configured to be welded to the end cap and the first electrode tab respectively to achieve electrical connection between the end cap and the first electrode tab.

2. The battery cell according to claim 1, wherein, A portion of the current collector is used to abut against and weld to the end cap to form a first welded portion, and another portion of the current collector is used to abut against and weld to the first electrode tab to form a second welded portion; The projection of the first welded portion along the thickness direction of the end cap and the projection of the second welded portion along the thickness direction of the end cap do not overlap.

3. The battery cell according to claim 2, wherein, The electrode assembly is wound along the central axis to form the first electrode tab, the first electrode tab including N layer structures arranged around the central axis, the extension direction of the central axis being parallel to the thickness direction of the end cap; The first electrode ear is composed of a first annular portion and a second annular portion surrounding the outside of the first annular portion. The number of layered structures in the first annular portion is N1, and the number of layered structures in the second annular portion is N2. N = N1 + N2, the value of |N1 - N2| is less than or equal to 2, and N1 and N2 are positive integers. The first annular portion is welded to the current collecting member to form a first part, and the second annular portion is welded to the current collecting member to form a second part connected to the first part. The second welded part is composed of the first part and the second part.

4. The battery cell according to claim 3, wherein, N3 consecutive layered structures in the first annular portion, located near the second annular portion, are welded to the current collecting member to form the first part. N4 consecutive layered structures in the second annular portion, located near the first annular portion, are welded to the current collecting member to form the second part. The N3 consecutive layered structures and the N4 consecutive layered structures are arranged consecutively, N4 > N3 ≥ 1, and N3 and N4 are positive integers.

5. The battery cell according to claim 3 or 4, wherein, M consecutive layered structures in all layered structures are welded to the current collector to form the second welded part, wherein 1 / 3≤M / N≤1 / 2, M≥2, and M is a positive integer.

6. The battery cell according to any one of claims 2-5, wherein, The end cap includes a cap body and a first protrusion protruding from the inner surface of the cap body in a direction facing the first electrode ear. The first protrusion is used to abut against and weld with the current collecting member to form the first welded portion, and to form a first clearance gap between the current collecting member and the cap body to avoid the second welded portion.

7. The battery cell according to claim 6, wherein, A first recess is formed on the end cap at a position corresponding to the first protrusion, extending from the outer surface of the cap body in the direction facing the electrode assembly. The bottom surface of the first recess is closer to the first tab than the inner surface of the cap body.

8. The battery cell according to claim 6 or 7, wherein, The first protrusion surrounds the outside of the cover body, and the first welded portion is located outside the second welded portion.

9. The battery cell according to claim 8, wherein, The outer side of the first protrusion abuts against the inner surface of the housing and is used for welding to the housing to close the opening.

10. The battery cell according to claim 8, wherein, The end cap also includes an extension surrounding the outside of the first protrusion, the surface of the extension facing the first tab abutting against and welded to the end face of the housing surrounding the opening to close the opening.

11. The battery cell according to claim 10, wherein, The battery cell is a cylindrical battery cell, and in the radial direction of the battery cell, the extension does not extend outward beyond the outer surface of the sidewall.

12. The battery cell according to any one of claims 8-11, wherein, The end cap further includes a second protrusion, and the cap body surrounds the outside of the second protrusion. The second protrusion protrudes from the inner surface of the cap body in a direction facing the first electrode tab. A second recess is formed on the end cap at a position corresponding to the second protrusion, recessed from the outer surface of the cap body in the direction facing the electrode assembly.

13. The battery cell according to claim 12, wherein, The area of ​​the second protrusion opposite to the bottom surface of the second concave portion is provided with a weak portion, which is used to rupture when the internal pressure of the battery cell reaches a threshold, so as to release the internal pressure.

14. The battery cell according to claim 13, wherein, A second clearance gap is formed between the second protrusion and the current collecting member.

15. The battery cell according to claim 6 or 7, wherein, The cover body surrounds the outside of the first protrusion, and the first welded part is located inside the second welded part.

16. The battery cell according to claim 15, wherein, A first recess is formed on the end cap at a position corresponding to the first protrusion, which is recessed from the outer surface of the cap body in the direction facing the electrode assembly; The bottom surface of the first recess is provided with a groove, and the bottom of the groove is used to weld with the current collecting component to form the first welded part.

17. The battery cell according to claim 16, wherein, Along the direction from the first electrode tab to the end cap, the first welded portion does not extend beyond the bottom surface of the first recess.

18. The battery cell according to any one of claims 15-17, wherein, The end cap further includes a second protrusion surrounding the outside of the cap body, the second protrusion protruding from the inner surface of the cap body in a direction facing the first electrode tab.

19. The battery cell according to claim 18, wherein, The second protrusion abuts against the first electrode tab and supports the first electrode tab.

20. The battery cell according to claim 18 or 19, wherein, The second protrusion is spaced apart from the current collecting member.

21. The battery cell according to any one of claims 18-20, wherein, The outer side of the second protrusion abuts against the inner surface of the housing and is used for welding to the housing to close the opening.

22. The battery cell according to claim 21, wherein, In the thickness direction of the end cap, the end face of the housing surrounding the opening is closer to the first tab than the outer surface of the cap body.

23. The battery cell according to any one of claims 18-22, wherein, A second recess is formed on the end cap at a position corresponding to the second protrusion, recessed from the outer surface of the cap body in the direction facing the electrode assembly, and the bottom surface of the second recess is closer to the first tab than the inner surface of the cap body.

24. The battery cell according to any one of claims 14-23, wherein, The cover body is provided with a weak part, which is used to rupture when the internal pressure of the battery cell reaches a threshold, so as to release the internal pressure.

25. The battery cell according to any one of claims 6-24, wherein, The current collection component is a flat plate structure.

26. The battery cell according to any one of claims 6-25, wherein, The first protrusion supports the first electrode tab via the current collecting member.

27. The battery cell according to any one of claims 2-5, wherein, The current collection component includes: The first collector section is used to abut against and weld with the end cap to form the first welded section; The second current collector is used to abut against and weld with the first electrode tab to form the second welded part. The second current collector protrudes from the surface of the first current collector facing the electrode assembly, and the second current collector has a relief recess on the side away from the electrode assembly, the relief recess being used to avoid the second welded part.

28. The battery cell according to claim 27, wherein, The end cap includes: A cover body for welding to the first current collector and forming the first welded portion; and The first protrusion surrounds the outer side of the cover body and protrudes from the inner surface of the cover body in the direction facing the first electrode tab.

29. The battery cell according to claim 28, wherein, The first protrusion is used to abut against the first electrode tab to support the first electrode tab.

30. The battery cell according to claim 28 or 29, wherein, A first recess is formed on the end cap at a position corresponding to the first protrusion, extending from the outer surface of the cap body in the direction facing the electrode assembly. The bottom surface of the first recess is closer to the first tab than the inner surface of the cap body.

31. The battery cell according to any one of claims 28-30, wherein, The outer side of the first protrusion abuts against the inner surface of the housing and is used for welding to the housing to close the opening.

32. The battery cell according to any one of claims 28-30, wherein, The end cap includes an extension surrounding the outside of the first protrusion, the surface of the extension facing the first tab abutting against and welded to the end face of the housing surrounding the opening to close the opening.

33. The battery cell according to any one of claims 28-32, wherein, In the thickness direction of the end cap, the end face of the housing surrounding the opening is closer to the first tab than the outer surface of the cap body.

34. The battery cell according to any one of claims 28-33, wherein, The end cap further includes a second protrusion, the cap body surrounds the outside of the second protrusion, the second protrusion protrudes from the inner surface of the cap body in the direction facing the first electrode tab and extends into the relief recess; A second recess is formed on the end cap at a position corresponding to the second protrusion, recessed from the outer surface of the cap body in the direction facing the electrode assembly.

35. The battery cell according to claim 34, wherein, A weak portion is provided in the area of ​​the second protrusion opposite to the bottom surface of the second concave portion. The weak portion is used to rupture when the internal pressure of the battery cell reaches a threshold, so as to release the internal pressure. The clearance recess is also used to separate the second current collector from the weak portion.

36. The battery cell according to any one of claims 1-35, wherein, The first electrode tab is the negative electrode tab, and the base material of the shell is steel.

37. The battery cell according to any one of claims 1-36, wherein, The base material of the housing is the same as the base material of the end cap.

38. The battery cell according to any one of claims 1-37, wherein, The battery cell is a cylindrical battery cell.

39. A battery comprising a plurality of battery cells according to any one of claims 1-38.

40. An electrical device comprising the battery of claim 39, the battery being used to provide electrical energy.

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