Battery monomer and preparation method thereof, battery and power utilization device

Abstract

The invention discloses a battery monomer, a preparation method thereof, a battery and a power utilization device. The battery cell comprises: a housing provided with a pole; the electrode assembly is arranged in the shell and comprises an active material coating part and a tab, and the tab is connected with the pole in a welding manner to form a welding mark; the welding mark comprises a first welding seam and a second welding seam, the second welding seam is located on one side of the width direction of the first welding seam and partially overlaps with the first welding seam, and the maximum thickness of the first welding seam is smaller than that of the second welding seam. In the technical scheme of the embodiment of the invention, the first welding seam is formed on one side of the width direction of the second welding seam, so that on one hand, the first welding seam can be used for effectively reducing the probability of welding cracks of multiple layers of tab pieces of the tab and reducing overcurrent temperature rise, thereby reducing the probability of thermal runaway of the electrode assembly due to excessive temperature rise; and on the other hand, the anti-stripping strength of the welding marks on the tabs can be increased, and the reliability of the single battery is remarkably improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a battery cell and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] Energy conservation and emission reduction are the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages in energy conservation and environmental protection. For electric vehicles, battery technology is an important factor in their development.

[0003] When the tabs and poles of the battery cells in the related art are connected, the welds formed are prone to breakage, resulting in poor reliability of the battery cells. Summary of the invention

[0004] In view of the above problems, the present application provides a battery cell, a battery and an electrical device, which can reduce the probability of foreign matter entering the interior of the battery cell and improve the reliability of the battery cell.

[0005] In the first aspect, the present application provides a battery cell comprising: a shell, the shell being provided with a pole; an electrode assembly, the electrode assembly being arranged in the shell, the electrode assembly comprising an active material coating portion and a pole ear connected to the active material coating portion, the pole ear being welded to the pole and forming a weld mark; wherein the weld mark comprises a first weld and a second weld, the second weld being located on one side in the width direction of the first weld and partially overlapping with the first weld, and the maximum thickness of the first weld being less than the maximum thickness of the second weld.

[0006] In the technical solution of the embodiment of the present application, since the edge of the second weld is prone to cracks and affects the connection strength of the weld mark, a first weld is formed on one side in the width direction of the second weld. The first weld can effectively reduce the probability of welding cracks in the multi-layer tab sheets of the tab and reduce the over-current temperature rise, thereby reducing the probability of thermal runaway of the electrode assembly due to excessive temperature rise. On the other hand, it can increase the anti-peel strength of the weld mark on the tab and significantly improve the reliability of the battery cell.

[0007] In some embodiments, the ratio of the maximum thickness of the first weld to the thickness of the tab is 0.8-1.2. In the above technical solution, by limiting the ratio of the maximum thickness of the first weld to the thickness of the tab to the above range, on the one hand, the welding power when forming the first weld can be reduced, the heat input when forming the first weld can be reduced, and the risk of fracture of the multi-layer tab sheet of the tab can be reduced. On the other hand, the influence of the heat input on the multi-layer tab sheet at the position when forming the second weld can be reduced, further reducing the proportion of thermal cracks in the multi-layer tab sheet, improving the welding quality of the tab and the pole, and thus improving the reliability of the battery cell.

[0008] In some embodiments, the ratio of the maximum thickness of the first weld to the thickness of the tab is 0.8 to 1. In the above technical solution, by limiting the ratio of the maximum thickness of the first weld to the thickness of the tab to the above range, the welding quality between the tab and the pole can be further improved, and the reliability of the battery cell can be improved.

[0009] In some embodiments, the width of the first weld is 0.5 mm to 3.0 mm. In the above technical solution, by limiting the width of the first weld to meet the above conditions, the first weld can partially overlap with the second weld in the width direction, so that when the molten pool of the second weld shrinks, it will not affect the multi-layer pole tab sheet at the first weld, further reducing the proportion of thermal cracks in the multi-layer pole tab sheet, and improving the reliability of the electrical connection between the pole column and the pole tab.

[0010] In some embodiments, the maximum thickness of the second weld is greater than the thickness of the pole lug, so that the second weld penetrates the pole lug and the first weld along its thickness direction and extends into the pole column. In the above technical solution, by limiting the maximum thickness of the second weld to be greater than the thickness of the pole lug, the molten pool of the second weld can penetrate the pole lug and extend into the pole column. After the molten pool of the second weld solidifies, the pole lug and the pole column can be connected together to achieve electrical connection between the pole lug and the pole column. Since the heat input formed by the second weld has little effect on the multi-layer pole lug sheet at the first weld, the proportion of thermal cracks in the multi-layer pole lug sheet can be reduced, and the welding quality of the pole lug and the pole column can be improved, thereby improving the reliability of the battery cell.

[0011] In some embodiments, the width of the second weld is greater than twice the width of the first weld. In the above technical solution, by limiting the width of the second weld to meet the above conditions, the first weld can partially overlap with the second weld in the width direction, so that the edge of the molten pool of the second weld is located inside the molten pool of the first weld, so that when the molten pool of the second weld shrinks, it will not affect the multi-layer pole tab sheet at the first weld, further reducing the proportion of thermal cracks in the multi-layer pole tab sheet, and improving the reliability of the electrical connection between the pole column and the pole tab.

[0012] In some embodiments, the weld mark further includes a third weld, the third weld and the second weld are respectively located on opposite sides of the first weld in the width direction, and the third weld partially overlaps the first weld, and the maximum thickness of the third weld is less than the thickness of the tab. In the above technical solution, by providing the third weld, on the one hand, the welding microcracks of the multi-layer tab sheets at the edge of the first weld can be repaired, and on the other hand, the welding connection strength between the tab and the pole can be greatly improved.

[0013] In some embodiments, the ratio of the maximum thickness of the third weld to the thickness of the tab is 0.5-0.8. In the above technical solution, by limiting the ratio of the maximum thickness of the third weld to the thickness of the tab within the above range, on the one hand, the welding power when forming the third weld can be reduced, the heat input when forming the third weld can be reduced, and the risk of fracture of the multi-layer tab sheet of the tab can be reduced. On the other hand, the welding microcracks generated by the first weld can be better repaired, the proportion of thermal cracks in the multi-layer tab sheet can be further reduced, and the welding quality of the tab and the pole column can be improved, thereby improving the reliability of the battery cell.

[0014] In some embodiments, the maximum thickness of the third weld is less than the maximum thickness of the first weld. In the above technical solution, by limiting the maximum thickness of the third weld to be less than the maximum thickness of the first weld, the transition from high-power welding to low-power welding can, on the one hand, repair the micro cracks of the multi-layer tab sheet at the edge of the molten pool of the first weld, effectively reduce the probability of welding cracks in the multi-layer tab sheet of the tab, reduce overcurrent temperature rise, and thus reduce the probability of thermal runaway of the electrode assembly due to excessive temperature rise, and on the other hand, increase the peeling strength of the weld mark on the tab, significantly improving the reliability of the battery cell.

[0015] In some embodiments, the width of the third weld is 0.5 mm to 2.0 mm. In the above technical solution, by limiting the width of the third weld to meet the above conditions, the third weld can partially overlap with the first weld in the width direction, so that when the molten pool of the third weld shrinks, it will not affect the multi-layer pole tab sheet at the first weld, further reducing the proportion of thermal cracks in the multi-layer pole tab sheet and improving the reliability of the electrical connection between the pole column and the pole tab.

[0016] In some embodiments, each of the first weld, the second weld, and the third weld includes a plurality of weld sections, which are arranged and connected in the length direction of the respective welds. The plurality of weld sections are arranged and connected in the length direction of the respective welds to form a continuous weld, improve welding quality, and further improve the reliability of the battery cell.

[0017] In some embodiments, the first weld is provided on both sides of the second weld in the width direction, and the second weld and the third weld are provided on both sides of the first weld in the width direction. In the above technical solution, compared with the welding method of the tab and the pole of the battery cell in the related art, in the present application, when the tab is peeled off or pulled, the peeling force of the multi-layer tab sheet connected to the molten pool of the third weld can be converted into a shear force, thereby greatly improving the welding connection strength between the tab and the pole.

[0018] In some embodiments, the pole is provided with a receiving portion, and at least a portion of the pole ear extends into the receiving portion and is welded to the pole. The hollow structure of the receiving portion can reduce the weight of the pole to a certain extent, so as to improve the weight energy density of the battery cell and the battery. On the other hand, the pole ear can be accommodated in the receiving portion, which improves the assembly efficiency of the pole ear, saves the space occupied by the pole ear, and makes full use of the space of the battery cell, so that the cooperation between the bracket and the pole, and between the bracket and the pole ear are tighter and more reliable, making the structure of the battery cell more compact, which is more conducive to improving the energy density of the battery cell.

[0019] In some embodiments, the accommodating portion includes a first accommodating groove, the surface of the pole facing the active material coating portion is the inner end face of the pole, the notch of the first accommodating groove is formed on the inner end face of the pole, and at least part of the pole ear is accommodated in the first accommodating groove. In the above technical scheme, on the one hand, the first accommodating groove provided on the pole can reduce the weight of the pole to a certain extent, so as to improve the weight energy density of the battery cell and the battery; on the other hand, since the notch of the first accommodating groove is formed on the inner end face of the pole, and the inner end face of the pole is the surface of the pole close to the active material coating portion, the first accommodating groove can be opened toward the active material coating portion, thereby facilitating the pole ear to extend into the first accommodating groove, thereby improving assembly efficiency. Moreover, this form of first accommodating groove is easy to process and improves production efficiency.

[0020] In some embodiments, the accommodation portion includes a second accommodation groove, the surface of the pole away from the active material coating portion is the outer end face of the pole, the notch of the second accommodation groove is formed on the outer end face of the pole, the second accommodation groove is connected to the interior of the shell through a perforation, and the pole ear is penetrated through the perforation and at least partially accommodated in the second accommodation groove. In the above technical solution, on the one hand, the pole is provided with a second accommodation groove, which can reduce the weight of the pole to a certain extent, so as to improve the weight energy density of the battery cell and the battery; on the other hand, since the notch of the second accommodation groove is formed on the outer end face of the pole, and the outer end face of the pole is the surface of the pole away from the active material coating portion, the second accommodation groove can be opened in the direction away from the active material coating portion, so that when at least part of the pole ear is accommodated in the second accommodation groove, the pole ear can be easily stored and arranged through the notch of the second accommodation groove, and the electrical connection operation between the pole ear and the pole can be easily realized through the notch of the second accommodation groove, thereby reducing the difficulty of producing the battery cell and improving the production efficiency of the battery cell.

[0021] In some embodiments, the shell includes a shell cover and a shell body with an opening, the shell cover covers the opening, and the pole is arranged on the shell cover and / or the wall of the shell body opposite to the opening. In the above technical solution, the pole is arranged on the shell cover, which can simplify the installation steps of the pole on the one hand, and simplify the structure of the mold and reduce the size of the mold on the other hand, which is conducive to reducing costs; the pole is arranged on the wall of the shell body opposite to the opening, which can improve the structural strength of the shell body, and after the electrode assembly is installed in the shell body, it is convenient to connect the pole ear with the pole, which is conducive to improving production efficiency.

[0022] In a second aspect, the present application provides a battery, which includes the battery cell in the above embodiment.

[0023] In the technical solution of the embodiment of the present application, by adopting the above-mentioned battery monomer, the overcurrent temperature rise can be reduced, the probability of thermal runaway can be reduced, and the reliability of the battery can be improved.

[0024] In a third aspect, the present application provides an electrical device, which includes the battery in the above embodiment.

[0025] In the technical solution of the embodiment of the present application, the reliability of the electrical device can be improved by adopting the above-mentioned battery.

[0026] In a fourth aspect, the present application provides a method for preparing a battery cell, comprising the following steps: providing a shell and an electrode assembly, the shell being provided with a pole, the electrode assembly comprising an active material coating portion and a pole ear connected to the active material coating portion; loading the electrode assembly into the shell; welding the pole ear and the pole ear to form a first weld and a second weld, the second weld being located on one side in the width direction of the first weld and partially overlapping with the first weld, the maximum thickness of the first weld being less than the maximum thickness of the second weld.

[0027] In the technical solution of the embodiment of the present application, since the edge of the second weld is prone to cracks and affects the connection strength of the weld mark, a first weld is formed on one side in the width direction of the second weld. The first weld can effectively reduce the probability of welding cracks in the multi-layer tab sheets of the tab and reduce the over-current temperature rise, thereby reducing the probability of thermal runaway of the electrode assembly due to excessive temperature rise. On the other hand, it can increase the anti-peel strength of the weld mark on the tab and significantly improve the reliability of the battery cell.

[0028] In some embodiments, the second weld is formed after the first weld. In the process of welding the tab to the pole, the first weld is formed first and then the second weld. Since the maximum thickness of the first weld formed first is less than the maximum thickness of the second weld formed later, the welding power when forming the first weld is less than the welding power when forming the second weld. The gradual transition from low-power welding to high-power welding can effectively reduce the probability of welding cracks in the multi-layer tab sheets of the tab and reduce the overcurrent temperature rise, thereby reducing the probability of thermal runaway of the electrode assembly due to excessive temperature rise. On the other hand, the peeling strength of the weld mark on the tab can be increased, significantly improving the reliability of the battery cell.

[0029] In some embodiments, when welding the pole tab and the pole column, a third weld is also formed, and the third weld is formed after the first weld; wherein the third weld and the second weld are respectively located on opposite sides of the first weld in the width direction, and the third weld partially overlaps with the first weld, and the thickness of the third weld is less than the thickness of the pole tab. In the above technical solution, by providing the third weld, on the one hand, the welding microcracks of the multi-layer pole tab sheets at the edge of the first weld can be repaired, and on the other hand, the welding connection strength between the pole tab and the pole column can be greatly improved.

[0030] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0032] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0033] Figure 2 An exploded view of the structure of a battery provided in some embodiments of the present application;

[0034] Figure 3 A three-dimensional diagram of a battery cell provided for some embodiments of the present application;

[0035] Figure 4 A structural cross-sectional view of a battery cell provided in some embodiments of the present application;

[0036] Figure 5A schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application;

[0037] Figure 6 for Figure 5 Schematic diagram of welding the pole ear and pole of the battery cell shown in ;

[0038] Figure 7 for Figure 6 A bottom view of the structure shown in ;

[0039] Figure 8 for Figure 5 Schematic diagram of welding the pole ear and pole of the battery cell shown in ;

[0040] Fig. 9 for Figure 8 A bottom view of the structure shown in ;

[0041] Fig.10 for Figure 5 Schematic diagram of welding the pole ear and pole of the battery cell shown in ;

[0042] Fig.11 for Fig.10 A bottom view of the structure shown in ;

[0043] Fig.12 A schematic diagram of a partial structure of a battery cell provided in some other embodiments of the present application;

[0044] Fig.13 for Fig.12 Schematic diagram of welding the pole ear and pole of the battery cell shown in ;

[0045] Fig.14 A partial cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application;

[0046] Fig.15 A partial cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application;

[0047] Fig.16 A partial cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application;

[0048] Fig.17 A partial cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application;

[0049] Fig.18 A partial cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application;

[0050] Fig.19 This is a flow chart of the preparation of battery cells according to some embodiments of the present application.

[0051] The reference numerals in the specific implementation manner are as follows:

[0052] Electric device 1000, battery 100, controller 200, motor 300,

[0053] The first direction is Z, the second direction is X, the third direction is Y, and the axial direction of the pole is R.

[0054] Battery cell 10,

[0055] Box 20, first part 201, second part 202,

[0056] Shell 11, shell body 111, opening 1110, shell cover 112, mounting hole 113,

[0057] Pole 12, positive pole 1201, negative pole 1202, accommodating portion 121, first accommodating groove 12110, first end wall 12111, first sinking groove 12112, first side wall 12113, second accommodating groove 12120, second end wall 12121, second sinking groove 12122, second side wall 12123, through hole 12130, pole inner end surface 122, pole outer end surface 123, first groove 126, spacer 127, cover plate 13; first conductive member 131; second groove 1311; second conductive member 132;

[0058] Electrode assembly 2, active material coating portion 21, tab 22,

[0059] Welding mark 23, first weld 231, second weld 232, third weld 233,

[0060] Bracket 3, through hole 314, insulating member 4, explosion-proof valve 6, slot cover 7. DETAILED DESCRIPTION

[0061] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0063] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0064] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0065] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0066] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0067] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0068] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0069] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0070] In the battery cells of the related art, the tabs are generally pre-welded together by ultrasonic welding, and then the pre-welded tabs are welded to the poles by laser welding.

[0071] However, due to the material limitations of the tabs, such as the large linear expansion coefficient and poor fluidity of the aluminum tab material, the molten aluminum material will not fill the gap in time, and will shrink, resulting in the disconnection between the molten pool and part of the aluminum foil of the tab, resulting in the isolation of the current path from the tab to the pole, increasing the overcurrent internal resistance, and increasing the overcurrent temperature rise, causing the electrode assembly to thermally runaway due to excessive temperature rise. In addition, the weld strength after laser welding between the tab and the pole is low, and it is easy to be pulled, causing the weld crack to increase. In severe cases, it will completely break from the edge of the weld and fall off, resulting in poor reliability of the battery cell.

[0072] In order to improve the reliability of the battery cell, the electrode and the pole ear of the battery cell of the present application form a weld mark including at least a first weld and a second weld after welding. The first weld serves as a base weld and partially overlaps with the second weld, which can effectively reduce the proportion of cracks after laser welding of the pole ear and the pole, increase the anti-peel strength of the weld mark on the pole ear, and reduce the probability of thermal runaway of the battery cell, thereby improving the reliability of the battery cell.

[0073] The battery cell disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0074] For the convenience of description, the following embodiments are described by taking an electric device 1000 of an embodiment of the present application as a vehicle as an example.

[0075] Please refer to Figure 1 , Figure 1A schematic diagram of the structure of a vehicle provided for some embodiments of the present application. The vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle, and the battery 100 may be provided at the bottom, head or tail of the vehicle. The battery 100 may be used to power the vehicle, for example, the battery 100 may be used as an operating power source for the vehicle. The vehicle may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle.

[0076] In some embodiments of the present application, the battery 100 can be used not only as an operating power source for the vehicle, but also as a driving power source for the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0077] Please refer to Figure 2 , Figure 2 An exploded view of a battery 100 provided for some embodiments of the present application. The battery 100 includes a case 20 and a battery cell 10, and the battery cell 10 is contained in the case 20. Among them, the case 20 is used to provide a storage space for the battery cell 10, and the case 20 can adopt a variety of structures. In some embodiments, the case 20 may include a first part 201 and a second part 202, and the first part 201 and the second part 202 cover each other, and the first part 201 and the second part 202 jointly define a storage space for accommodating the battery cell 10. The second part 202 may be a hollow structure with one end open, and the first part 201 may be a plate-like structure, and the first part 201 covers the open side of the second part 202, so that the first part 201 and the second part 202 jointly define a storage space; the first part 201 and the second part 202 may also be hollow structures with one side open, and the open side of the first part 201 covers the open side of the second part 202. Of course, the box body 20 formed by the first part 201 and the second part 202 can be in various shapes, such as a cylinder, a cuboid, etc.

[0078] In the battery 100, there may be multiple battery cells 10, and the multiple battery cells 10 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 10 are both connected in series and in parallel. The multiple battery cells 10 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 10 is accommodated in the box 20; of course, the battery 100 may also be a battery 100 module formed by connecting multiple battery cells 10 in series, in parallel, or in a mixed connection, and then the multiple battery 100 modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 20. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 10.

[0079] Each battery cell 10 may be a secondary battery or a primary battery, or a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 10 may be cylindrical, flat, rectangular, or in other shapes.

[0080] Please refer to Figure 3 and Figure 4 , Figure 3 Schematic diagram of the exploded structure of a battery cell 10 provided in some embodiments of the present application. Figure 4 The structure of the battery cell 10 provided in some embodiments of the present application is a cross-sectional view. The battery cell 10 refers to the smallest unit constituting the battery 100. The battery cell 10 includes a housing 11 and an electrode assembly 2. The housing 11 is provided with a pole 12, and the housing 11 may include a housing body 111 and a housing cover 112.

[0081] The shell cover 112 refers to a component that covers the opening 1110 of the shell body 111 to isolate the internal environment of the battery cell 10 from the external environment. Without limitation, the shape of the shell cover 112 can be adapted to the shape of the shell body 111 to match the shell body 111. Optionally, the shell cover 112 can be made of a material with a certain hardness and strength (such as an aluminum alloy), so that the shell cover 112 is not easily deformed when squeezed and collided, so that the battery cell 10 can have a higher structural strength and the reliability can also be improved. Functional components such as electrode terminals can be provided on the shell cover 112. The electrode terminal can be used to electrically connect to the electrode assembly 2 for outputting or inputting electrical energy of the battery cell 10. The material of the shell cover 112 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose any special restrictions on this.

[0082] The shell body 111 is a component used to cooperate with the shell cover 112 to form the internal environment of the battery cell 10, wherein the formed internal environment can be used to accommodate the electrode assembly 2, the electrolyte and other components. The shell body 111 and the shell cover 112 can be independent components, and an opening 1110 can be set on the shell body 111, so that the shell cover 112 covers the opening 1110 to form the internal environment of the battery cell 10. Without limitation, the shell cover 112 and the shell body 111 can also be integrated. Specifically, the shell cover 112 and the shell body 111 can form a common connection surface before other components are put into the shell, and when it is necessary to encapsulate the interior of the shell body 111, the shell cover 112 covers the shell body 111. The shell body 111 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell body 111 can be determined according to the specific shape and size of the electrode assembly 2. The shell 111 may be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special limitation on this.

[0083] The electrode assembly 2 is a component in the battery cell 10 where an electrochemical reaction occurs. One or more electrode assemblies 2 may be contained in the housing 11. The electrode assembly 2 includes an active material coating portion 21 and a tab 22 connected to the active material coating portion 21. Specifically, the electrode assembly 2 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The portion of the positive electrode sheet and the negative electrode sheet with active material constitutes the active material coating portion 21 of the electrode assembly 2, and the portion of the positive electrode sheet and the negative electrode sheet without active material each constitutes a tab. The positive electrode tab and the negative electrode tab may be located together at one end of the active material coating portion 21 or at both ends of the active material coating portion 21, respectively. During the charge and discharge process of the battery 100, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs connect the electrode terminals (such as poles) to form a current loop.

[0084] like Figure 3 and Figure 4 The battery cell 10 also includes a bracket 3, an insulating member 4 and an explosion-proof valve 6. The bracket 3 is arranged at one end of the active material coating portion 21. The bracket 3 is provided with a through hole 314, and the pole ear 22 passes through the through hole 314 to connect with the pole 12. The insulating member 4 is connected to the bracket 3 and wrapped together in the circumference of the electrode assembly 2. The insulating member 4 can be used to isolate the electrical connection components in the shell 11 from the shell 11 to reduce the risk of short circuit. Exemplarily, the insulating member 4 can be plastic, rubber, etc. Among them, the insulating member 4 and the bracket 3 can be connected by bonding or hot melt. Of course, the insulating member 4 and the bracket 3 can also be connected in other ways. The explosion-proof valve 6 is arranged on the shell 11, and the explosion-proof valve 6 is used to release the internal pressure when the internal pressure or temperature of the battery cell 10 reaches a threshold. Among them, the explosion-proof valve 6 can be arranged on the shell cover 112 or on the shell body 111.

[0085] Please refer to further Figure 5 , Figure 5 Schematic diagram of the partial structure of the battery cell 10 provided in some embodiments of the present application. The pole tab 22 is welded to the pole post 12 and forms a weld mark 23. The pole tab 22 and the pole post 12 can be welded to each other by laser welding. During the laser welding process, part of the structure of the pole tab 22 absorbs the laser energy and converts it into heat energy, causing the material to heat up and melt locally. After cooling and solidification, the pole tab 22 and the pole post 12 are connected, and a weld mark 23 is formed at the connection position between the pole tab 22 and the pole post 12. Of course, the pole tab 22 and the pole post 12 can also be connected by other welding methods.

[0086] Please continue to refer to Figure 5 , and further refer to Figure 6-Figure 9 , Figure 6 for Figure 5Schematic diagram of welding the pole ear 22 and the pole 12 of the battery cell 10 shown in FIG. Figure 7 for Figure 6 A bottom view of the structure shown in ; Figure 8 for Figure 5 Schematic diagram of welding the pole ear 22 and the pole 12 of the battery cell 10 shown in FIG. Fig. 9 for Figure 8 The weld mark 23 formed by welding the pole ear 22 to the pole 12 includes a first weld 231 and a second weld 232, wherein the second weld 232 is located on one side of the first weld 231 in the width direction, and the second weld 232 partially overlaps the first weld 231, and the maximum thickness of the first weld 231 is less than the maximum thickness of the second weld 232.

[0087] In the technical solution of the embodiment of the present application, since the edge of the second weld 232 is prone to cracks and affects the connection strength of the weld mark 23, a first weld 231 is formed on one side in the width direction of the second weld 232. The first weld 231 can be used to effectively reduce the probability of welding cracks in the multi-layer tab sheets of the tab 22 and reduce over-current temperature rise, thereby reducing the probability of thermal runaway of the electrode assembly 2 due to excessive temperature rise. On the other hand, the peeling strength of the weld mark 23 on the tab 22 can be increased, thereby significantly improving the reliability of the battery cell 10.

[0088] In the process of welding the electrode tab 22 to the electrode post 12 , the first weld 231 may be formed first, and then the second weld 232 may be formed.

[0089] Specifically, after the multiple tab sheets of the tab 22 are paired, they are ultrasonically welded to form a plate-like structure, which includes multiple layers of tab sheets. In the process of welding the tab 22 to the pole 12, the following can be formed: Figure 6 and Figure 7 The first weld 231 shown, the first weld 231 serves as a base weld, and the maximum thickness of the first weld 231 is relatively small, that is, the depth of the molten pool of the first weld 231 is relatively small, that is, the depth of the molten pool of the base weld is relatively small, and the required welding power is relatively small, which can greatly reduce the heat input in the initial stage of welding, thereby reducing the thermal shrinkage of the molten pool of the base weld and reducing the risk of fracture of the multi-layer pole ear sheets of the pole ear 22.

[0090] After forming the first weld 231, the Figure 8 and Fig. 9The second weld 232 shown is used as the main weld. The maximum thickness of the second weld 232 is large, that is, the depth of the molten pool of the second weld 232 is large, that is, the depth of the molten pool of the main weld is large, and the required welding power is large. Specifically, when welding the main weld, the edge of the molten pool of the main weld falls into the molten pool of the base weld that has been solidified into a solid structure. At this time, the shrinkage of the molten pool of the main weld will not affect the multi-layer pole tab sheet at the base molten pool, which can reduce the proportion of thermal cracks in the multi-layer pole tab sheet, and the welding of the main weld here can be equivalent to the welding of the solid adapter sheet in the related art, which can improve the reliability of the electrical connection between the pole 12 and the pole tab 22.

[0091] Through comparative experiments, it was found that compared with the welding method of the pole ear 22 and the pole 12 of the battery cell 10 in the related art, the proportion of thermal cracks in the pole piece can be reduced by 50% to 80%, and the anti-peeling force can be increased by 80% to 120%, which significantly improves the anti-peeling strength of the weld mark 23.

[0092] Therefore, in the above technical solution, since the maximum thickness of the first weld 231 formed first is smaller than the maximum thickness of the second weld 232 formed later, the welding power when forming the first weld 231 is smaller than the welding power when forming the second weld 232. The gradual transition from low-power welding to high-power welding can effectively reduce the probability of welding cracks in the multi-layer tab sheets of the tab 22 and reduce the over-current temperature rise, thereby reducing the probability of thermal runaway of the electrode assembly 2 due to excessive temperature rise. On the other hand, the peeling strength of the weld mark 23 on the tab 22 can be increased, thereby significantly improving the reliability of the battery cell 10.

[0093] Of course, in the process of welding the pole tab 22 to the pole column 12, the second weld 232 can be formed first and then the first weld 231 can be formed. The first weld 231 can also effectively reduce the probability of welding cracks in the multi-layer pole tab sheets of the pole tab 22, reduce over-current temperature rise, and thus reduce the probability of thermal runaway of the electrode assembly 2 due to excessive temperature rise, increase the anti-peel strength of the weld mark 23 on the pole tab 22, and significantly improve the reliability of the battery cell 10.

[0094] Please refer again Figure 6 The maximum thickness of the first weld 231 is H1, the thickness of the tab 22 is H, and the ratio of the maximum thickness H1 of the first weld 231 to the thickness H of the tab 22 is 0.8-1.2.

[0095] The "maximum thickness" of the first weld 231 refers to the depth of the molten pool of the first weld 231, that is, the depth of the molten pool of the above-mentioned bottom weld, and the molten pool depth of the bottom weld is equal to the distance between the top of the molten pool and the bottom of the molten pool, and the position of the bottom weld can be determined according to the preset position of the main weld (that is, the second weld 232). For example, the ratio H1 / H of the maximum thickness of the first weld 231 to the thickness of the tab 22 can be 0.8, 0.9, 1, 1.1, 1.2, etc.

[0096] In the above technical scheme, by limiting the ratio of the maximum thickness of the first weld 231 to the thickness of the pole lug 22 within the above range, on the one hand, the welding power when forming the first weld 231 can be reduced, the heat input when forming the first weld 231 can be reduced, and the risk of fracture of the multi-layer pole lug sheets of the pole lug 22 can be reduced. On the other hand, the influence of the heat input on the multi-layer pole lug sheets at this position when forming the second weld 232 can be reduced, further reducing the proportion of thermal cracks in the multi-layer pole lug sheets, improving the welding quality of the pole lug 22 and the pole 12, thereby improving the reliability of the battery cell 10.

[0097] In an optional embodiment, the ratio of the maximum thickness of the first weld 231 to the thickness of the tab 22 is 0.8-1. That is, the maximum thickness of the first weld 231 is less than or equal to the thickness of the tab 22. For example, the ratio of the maximum thickness H1 of the first weld 231 to the thickness H of the tab 22 can be 0.8, 0.85, 0.9, 0.95, 1.

[0098] In the above technical solution, by limiting the ratio of the maximum thickness of the first weld 231 to the thickness of the pole tab 22 within the above range, the welding quality between the pole tab 22 and the pole 12 can be further improved, thereby improving the reliability of the battery cell 10.

[0099] like Figure 6 and Figure 7 As shown, the width L1 of the first weld 231 is 0.5 mm-3.0 mm. For example, the width L1 of the first weld 231 can be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3.0 mm, etc.

[0100] Among them, the "width" of the first weld 231 is a relative description. The width of the first weld 231 is relative to the length of the first weld 231. The length of the first weld 231 refers to the distance between the two joints of the first weld 231. Therefore, the width of the first weld 231 refers to the size of the first weld 231 in the direction perpendicular to its length.

[0101] In the above technical solution, the above conditions are met by limiting the width of the first weld 231 so that the first weld 231 can partially overlap with the second weld 232 in the width direction. In this way, when the molten pool of the second weld 232 shrinks, it will not affect the multi-layer pole tab sheets at the first weld 231, further reducing the proportion of thermal cracks in the multi-layer pole tab sheets and improving the electrical connection reliability between the pole 12 and the pole tab 22.

[0102] Please refer again Figure 8-Figure 9 The maximum thickness of the second weld 232 is H2, the thickness of the pole tab 22 is H, and H2 is greater than H, so that the second weld 232 penetrates the pole tab 22 and the first weld 231 along its thickness direction and extends into the pole 12.

[0103] Specifically, the second weld 232 serves as a main weld, and the molten pool depth of the main weld is greater than the thickness of the pole tab 22, so that the molten pool of the main weld can penetrate the pole tab 22 and the pole 12, thereby welding the pole tab 22 and the pole 12 together to form a conductive channel.

[0104] In the above technical solution, by limiting the maximum thickness of the second weld 232 to be greater than the thickness of the pole lug 22, the molten pool of the second weld 232 can penetrate the pole lug 22 and extend into the pole post 12. After the molten pool of the second weld 232 solidifies, the pole lug 22 and the pole post 12 can be connected together to achieve electrical connection between the pole lug 22 and the pole post 12. Since the heat input formed by the second weld 232 has little effect on the multi-layer pole lug sheet at the first weld 231, the proportion of thermal cracks in the multi-layer pole lug sheet can be reduced, and the welding quality of the pole lug 22 and the pole post 12 can be improved, thereby improving the reliability of the battery cell 10.

[0105] Please refer again Figure 8 The width of the second weld 232 is L2, the width of the first weld 231 is L1, and the width L2 of the second weld 232 is greater than twice the width L1 of the first weld 231.

[0106] Among them, the "width" of the second weld 232 is a relative description. The width of the second weld 232 is relative to the length of the second weld 232. The length of the second weld 232 refers to the distance between the two joints of the second weld 232. Therefore, the width of the second weld 232 refers to the size of the second weld 232 in the direction perpendicular to its length.

[0107] In the above technical solution, the above conditions are met by limiting the width of the second weld 232, so that the first weld 231 can partially overlap with the second weld 232 in the width direction, and the edge of the molten pool of the second weld 232 is located inside the molten pool of the first weld 231. In this way, when the molten pool of the second weld 232 shrinks, it will not affect the multi-layer pole tab sheets at the first weld 231, further reducing the proportion of thermal cracks in the multi-layer pole tab sheets and improving the electrical connection reliability between the pole 12 and the pole tab 22.

[0108] Please continue to refer to Figure 5-Figure 9 , and further refer to Figure 10-11 , Fig.10 for Figure 5 Schematic diagram of welding the pole ear 22 and the pole 12 of the battery cell 10 shown in FIG. Fig.11 for Fig.10 The weld mark 23 further includes a third weld 233 , the third weld 233 and the second weld 232 are respectively located on opposite sides of the first weld 231 in the width direction, and the third weld 233 partially overlaps the first weld 231 .

[0109] The maximum thickness of the third weld 233 is H3, the thickness of the pole tab 22 is H, and the maximum thickness H3 of the third weld 233 is less than the thickness H of the pole tab 22 .

[0110] Specifically, in the process of welding the pole ear 22 to the pole 12, it can be that firstly forming Figure 6 and Figure 7 The first weld 231 shown in FIG. Figure 8 and Fig. 9 The second weld 232 shown in FIG. Fig.11 and Fig.10 The third weld 233 shown in FIG. 1 may also be formed by first forming Figure 6 and Figure 7 The first weld 231 shown in FIG. Fig.11 and Fig.10 The third weld 233 shown finally forms Figure 8 and Fig. 9 The second weld 232 shown in FIG. 1 may also be formed by first forming Figure 6 and Figure 7 The first weld 231 shown in FIG. Figure 8 and Fig. 9 The second weld 232 shown, Fig.11 and Fig.10 A third weld 233 is shown.

[0111] The third weld 233 is used as a repair weld, and the maximum thickness of the repair weld is small, that is, the molten pool depth of the repair weld is small, and the required welding power is small, which can reduce the heat input during the welding process, thereby reducing the thermal shrinkage of the molten pool of the repair weld and reducing the risk of fracture of the multi-layer pole tab sheets of the pole tab 22.

[0112] Therefore, in the above technical solution, by providing the third weld 233, on the one hand, the welding microcracks of the multi-layer pole tab sheets at the edge of the first weld 231 can be repaired, and on the other hand, the welding connection strength between the pole tab 22 and the pole 12 can be greatly improved.

[0113] Please refer again Figure 10-11 , the ratio of the maximum thickness H3 of the third weld 233 to the thickness H of the tab 22 is 0.5-0.8. For example, the ratio of the maximum thickness H3 of the third weld 233 to the thickness H of the tab 22 can be 0.5, 0.6, 0.7, 0.8, etc.

[0114] Among them, the "maximum thickness" of the third weld 233 refers to the depth of the molten pool of the third weld 233, that is, the depth of the molten pool of the above-mentioned repair weld. The molten pool depth of the repair weld is equal to the distance between the top of the molten pool and the bottom of the molten pool, and the position of the repair weld can be determined according to the position of the base weld (that is, the first weld 231).

[0115] In the above technical scheme, by limiting the ratio of the maximum thickness of the third weld 233 to the thickness of the pole lug 22 within the above range, on the one hand, the welding power when forming the third weld 233 can be reduced, the heat input when forming the third weld 233 can be reduced, and the risk of fracture of the multi-layer pole lug sheets of the pole lug 22 can be reduced; on the other hand, the welding microcracks generated by the first weld 231 can be better repaired, and the proportion of thermal cracks in the multi-layer pole lug sheets can be further reduced, thereby improving the welding quality of the pole lug 22 and the pole 12, thereby improving the reliability of the battery cell 10.

[0116] Please refer again Figure 10-11 , the maximum thickness H3 of the third weld 233 is less than the maximum thickness H1 of the first weld 231 .

[0117] That is to say, the molten pool depth of the repair weld is smaller than that of the base weld, and the welding power used to form the repair weld is smaller than that used to form the base weld. Therefore, the heat input used to form the repair weld is smaller than the heat input used to form the base weld. Since the repair weld is located at the outer edge of the base weld and partially overlaps with the base weld, the cracks in the tab 22 generated after the repair weld is formed are lighter than those in the base weld. Therefore, the repair weld can repair the microcracks in the multi-layer tab sheets at the edge of the molten pool of the base weld, thereby further reducing the proportion of welding cracks in the multi-layer tab sheets.

[0118] Therefore, in the above technical solution, by limiting the maximum thickness of the third weld 233 to be smaller than the maximum thickness of the first weld 231 and transitioning from high-power welding to low-power welding, on the one hand, the micro cracks of the multi-layer pole tab sheets at the edge of the molten pool of the first weld 231 can be repaired, and the probability of welding cracks in the multi-layer pole tab sheets of the pole tab 22 can be effectively reduced, and the over-current temperature rise can be reduced, thereby reducing the probability of thermal runaway of the electrode assembly 2 due to excessive temperature rise. On the other hand, the peeling strength of the weld mark 23 on the pole tab 22 can be increased, and the reliability of the battery cell 10 can be significantly improved.

[0119] like Fig.10 and Fig.11 As shown, the width L3 of the third weld 233 is 0.5 mm-2.0 mm. For example, the width L3 of the third weld 233 is 0.5 mm, 1 mm, 1.5 mm, 2.0 mm, etc.

[0120] Among them, the "width" of the third weld 233 is a relative description. The width of the third weld 233 is relative to the length of the third weld 233. The length of the third weld 233 refers to the distance between the two joints of the third weld 233. Therefore, the width of the third weld 233 refers to the size of the third weld 233 in the direction perpendicular to its length.

[0121] In the above technical solution, the above conditions are met by limiting the width of the third weld 233 so that the third weld 233 can partially overlap with the first weld 231 in the width direction. In this way, when the molten pool of the third weld 233 shrinks, it will not affect the multi-layer pole tab sheets at the first weld 231, thereby further reducing the proportion of thermal cracks in the multi-layer pole tab sheets and improving the electrical connection reliability between the pole 12 and the pole tab 22.

[0122] In an optional embodiment, each of the first weld 231, the second weld 232, and the third weld 233 includes a plurality of weld sections, which are arranged and connected in the length direction of the respective welds. The plurality of weld sections are arranged and connected in the length direction of the respective welds to form a continuous weld, improve the welding quality, and further improve the reliability of the battery cell 10.

[0123] Please refer again Fig.10 and Fig.11 The second weld 232 has first welds 231 on opposite sides in the width direction, and each first weld 231 has second welds 232 and third welds 233 on opposite sides in the width direction.

[0124] Specifically, the weld mark 23 has a length direction and a width direction, the second weld 232 is located in the middle of the weld mark 23 in its width direction, the first welds 231 are respectively provided on both sides of the second weld 232 in the width direction, and each first weld 231 and the second weld 232 overlap in the width direction of the weld mark 23, and a third weld 233 is provided on the side of each first weld 231 away from the second weld 232, and each second weld 232 and the corresponding third weld 233 overlap in the width direction of the weld mark 23, so that the molten pool of the weld mark 23 roughly forms a "T" shape.

[0125] In the above technical scheme, compared with the welding method of the pole lug 22 and the pole post 12 of the battery cell 10 in the related art, in the present application, when the pole lug 22 is peeled off or pulled, the peeling force exerted on the multi-layer pole lug sheet connected to the molten pool of the third weld 233 can be converted into a shear force, thereby greatly improving the welding connection strength between the pole lug 22 and the pole post 12.

[0126] The housing 11 includes a housing cover 112 and a housing body 111 having an opening 1110 . The housing cover 112 covers the opening 1110 . The pole 12 is disposed on a wall of the housing cover 112 and / or the housing body 111 opposite to the opening 1110 .

[0127] Specifically, all the poles 12 of the battery cell 10 can be arranged on the shell cover 112; or all the poles 12 of the battery cell 10 can be arranged on the shell body 111, for example, all the poles 12 are arranged on the wall of the shell body 111 opposite to the opening 1110; or some of the poles 12 of the battery cell 10 are arranged on the shell cover 112, and the other part of the poles 12 are arranged on the shell body 111.

[0128] In the above technical solution, the pole 12 is arranged on the shell cover 112, which can simplify the installation steps of the pole 12 on the one hand, and simplify the structure of the mold and reduce the size of the mold on the other hand, which is beneficial to reducing costs; the pole 12 is arranged on the wall of the shell body 111 opposite to the opening 1110, which can improve the structural strength of the shell body 111. After the electrode assembly is installed in the shell body 111, it is convenient to connect the pole ear 22 with the pole 12, which is beneficial to improving production efficiency.

[0129] Please refer again Fig.10 and Fig.11 The pole ear 22 is welded to the side of the pole 12 facing the active material coating portion 21. In an embodiment in which the pole 12 is arranged on the wall of the shell body 111 opposite to the opening 1110, it is necessary to perform penetration welding on the pole ear 22 and the pole 12 from the outside of the shell body 111. In an embodiment in which the pole 12 is arranged on the shell cover 112, it is necessary to perform welding on the pole ear 22 and the pole 12 from the inside of the shell cover 112.

[0130] Please refer to Fig.12 and Fig.13 , Fig.12 A schematic diagram of a partial structure of a battery cell 10 provided in some other embodiments of the present application; Fig.13 for Fig.12 Schematic diagram of welding the pole tab 22 and pole post 12 of the battery cell 10 shown in FIG. The pole tab 22 is welded to the side of the pole post 12 away from the active material coating portion 21 , and the pole tab 22 and pole post 12 need to be welded from the outside of the shell body 111 or the shell cover 112 .

[0131] Please continue to refer to Figure 5 , and further refer to Fig.14 , Fig.14 The schematic diagram of a partial cross-section of a battery cell 10 provided in some embodiments of the present application. The pole 12 is provided with a receiving portion 121, which is communicated with the through hole 314, and at least a portion of the pole lug 22 passes through the through hole 314 and is received in the receiving portion 121, and the pole lug 22 is electrically connected to the pole 12. In other words, the pole 12 is configured as a hollow structure.

[0132] Among them, at least partially means that the pole lug 22 can be completely accommodated in the accommodating portion 121, or a part of the pole lug 22 can be accommodated in the accommodating portion 121. Since the pole 12 is provided with the accommodating portion 121, the hollow structure of the accommodating portion 121 can reduce the weight of the pole 12 to a certain extent, so as to improve the weight energy density of the battery cell 10 and the battery 100. On the other hand, the pole lug 22 can be accommodated in the accommodating portion 121, which improves the assembly efficiency of the pole lug 22, saves the space occupied by the pole lug 22, and makes full use of the space of the battery cell 10, so that the cooperation between the bracket 3 and the pole 12, and between the bracket 3 and the pole lug 22 are tighter and more reliable, so that the structure of the battery cell 10 is more compact, which is more conducive to the improvement of the energy density of the battery cell 10.

[0133] More specifically, the pole tab 22 is partially or completely contained in the containing portion 121, so that the portion of the pole tab 22 located in the containing portion 121 can occupy the space in the pole post 12, and the space occupied by the pole tab 22 in the housing 11 can be reduced. When the size of the housing 11 is fixed, some space can be saved in the housing 11 to accommodate a larger active material coating portion 21, thereby improving the volume energy density of the battery cell 10. For example, when the pole tab 22 is led out from the side of the active material coating portion 21 close to the pole post 12, the space occupied by the pole tab 22 between the active material coating portion 21 and the pole post 12 can be saved, the size of the active material coating portion 21 in the direction of leading out the pole tab 22 can be increased, the distance between the active material coating portion 21 and the pole post 12 can be reduced, and the energy density of the battery cell 10 can be improved.

[0134] At the same time, by accommodating at least part of the pole lug 22 in the accommodating portion 121, the space occupied by the battery cell 10 itself can be reduced, so that the battery 100 of the same volume can accommodate a larger number of battery cells 10, and the volume energy density of the battery 100 can be improved; in addition, accommodating at least part of the pole lug 22 in the accommodating portion 121 to occupy the space in the pole column 12 can reduce the redundancy of the pole lug 22 in the shell 11 to at least a certain extent, reduce the probability of short circuit between the pole lug 22 and the active material coating portion 21, reduce the probability of short circuit of the battery cell 10, and improve the working reliability and stability of the battery cell 10 and the battery 100.

[0135] It should be noted that, in the embodiment of the present application, the accommodation portion 121 may be located on the side of the pole 12 facing the active material coating portion 21 or on the side of the pole 12 away from the active material coating portion 21 .

[0136] For example, please refer again to Figure 5 and Fig.14 When the accommodating portion 121 is located on the side of the pole 12 facing the active material coating portion 21, the accommodating portion 121 includes a first accommodating groove 12110, and the surface of the pole 12 facing the active material coating portion 21 is the inner end face 122 of the pole. The notch of the first accommodating groove 12110 is formed on the inner end face 122 of the pole, and at least a portion of the pole ear 22 is accommodated in the first accommodating groove 12110.

[0137] Exemplarily, the first receiving groove 12110 is a groove body, and the groove body is a groove-shaped structure with a certain depth. For example, when the pole 12 is arranged on the upper end wall of the housing 11, and the inner end face 122 of the pole is the lower surface of the pole 12, the first receiving groove 12110 is formed as a receiving groove with a groove opening downward and a groove wall concave upward. For another example, when the pole 12 is arranged on the lower end wall of the housing 11, and the inner end face 122 of the pole is the upper surface of the pole 12, the first receiving groove 12110 is formed as a receiving groove with a groove opening upward and a groove wall concave downward.

[0138] In the above technical solution, on the one hand, the first receiving groove 12110 is provided on the pole 12 to reduce the weight of the pole 12 to a certain extent, so as to improve the weight energy density of the battery cell 10 and the battery 100; on the other hand, since the notch of the first receiving groove 12110 is formed on the inner end surface 122 of the pole, and the inner end surface 122 of the pole is the surface of the pole 12 close to the active material coating part 21, the first receiving groove 12110 can be opened toward the active material coating part 21, thereby facilitating the extension of the pole ear 22 into the first receiving groove 12110, thereby improving the assembly efficiency. Moreover, this type of first receiving groove 12110 is easy to process, thereby improving the production efficiency.

[0139] Furthermore, the first receiving groove 12110 can be easily processed to have a larger volume, so as to accommodate more pole ears 22. At the same time, since the first receiving groove 12110 is open toward the active material coating portion 21, the first receiving groove 12110 can also be used as a buffer and temporary storage structure for the electrolyte, so that more electrolyte can be accommodated in the shell 11. Since the battery cell 10 consumes electrolyte during the charging and discharging process, when there is more electrolyte, the service life of the battery cell 10 can be extended. Also, because the first receiving groove 12110 is open toward the active material coating portion 21, the first receiving groove 12110 can also be used as a receiving and buffer structure for gas production inside the electrode assembly 2, thereby reducing the expansion of the battery cell 10 and improving the reliability and stability of the battery cell 10.

[0140] In addition, since the first receiving groove 12110 is located on the inner side of the pole 12, external foreign matter and impurities are not easy to enter the first receiving groove 12110, which can reduce the impact of external foreign matter and impurities on the electrode assembly 2, improve the working stability and reliability of the electrode assembly 2, and further improve the stability and reliability of the battery cell 10 and the battery 100.

[0141] Please refer again Figure 5 In the embodiment of the present application, the connection method between the pole 12 and the housing 11 is not limited, for example, it can be welding or riveting. For example, when the two are matched by riveting, the housing 11 has a mounting hole 113, and the pole 12 is riveted and installed at the mounting hole 113. Of course, it is understandable that when the two are matched by welding or other methods, the housing 11 can also be provided with a mounting hole 113 to facilitate the pole 12 to be installed on the housing 11 through the mounting hole 113, which is not limited here.

[0142] At the same time, the first receiving groove 12110 can be arranged corresponding to the position of the mounting hole 113, or in other words, on the projection plane perpendicular to the axial direction R of the pole 12, the orthographic projection of the first receiving groove 12110 is located within the orthographic projection range of the mounting hole 113, so that the first receiving groove 12110 can have a greater depth to accommodate more pole lugs 22, thereby further reducing the space occupied by the pole lugs 22 in the housing 11. Specifically, when the housing 11 is provided with a mounting hole 113 and the pole 12 is mounted in the mounting hole 113, along the axial direction R of the pole 12, the depth H1 of the first receiving groove 12110 is greater than or equal to the minimum distance H2 from the inner end face 122 of the pole to the mounting hole 113.

[0143] It should be noted that the specific shape of the first receiving groove 12110 is not limited, and can be a regular shape or an irregular shape, such as a cylindrical groove with a rectangular, elliptical, or racetrack cross section, or a trapezoidal groove with a rectangular cross section and a gradually changing cross section size, or a hemispherical groove with a circular cross section and a gradually changing cross section size, or a hemispherical groove with an elliptical cross section and a gradually changing cross section size, etc. Therefore, the depth H1 of the first receiving groove 12110 refers to: the maximum depth of the first receiving groove 12110 along the axial direction R of the pole 12.

[0144] Since in the axial direction R of the pole 12, the depth H1 of the first receiving groove 12110 is greater than or equal to the minimum distance H2 from the inner end face 122 of the pole to the mounting hole 113, the volume of the pole 12 can be fully utilized, so that the first receiving groove 12110 has a larger depth, which is conducive to accommodating more pole ears 22, thereby further reducing the space occupied by the pole ears 22 in the shell 11 to a greater extent, further improving the energy density of the battery cell 10, and further reducing the redundancy of the pole ears 22 in the shell 11; at the same time, since the first receiving groove 12110 has a larger depth, it can also accommodate the gas production of the electrode assembly 2, improve the reliability and stability of the battery cell 10, and can also accommodate more electrolyte to increase the service life of the battery cell 10.

[0145] Please refer again Figure 5 and Fig.14 In order to improve the stability and reliability of the electrical connection between the active material coating portion 21 and the pole 12, in some embodiments of the present application, the electrical connection position between the pole ear 22 and the pole 12 can be located on the groove wall of the first accommodating groove 12110 formed by the accommodating portion 121.

[0146] Exemplarily, the pole lug 22 and the pole post 12 can be electrically connected by welding, and the electrical connection position is the welding position of the pole lug 22 and the pole post 12. At the same time, the welding method of the pole lug 22 and the pole post 12 is not limited, for example, it can be laser welding, and according to factors such as the position, angle, or structure of the welding part, vertical welding, inclined welding, lap welding, edge sealing welding, etc. can be selected. In other embodiments of the present application, the pole lug 22 and the pole post 12 can also be electrically connected by other methods instead of welding, such as by providing conductive glue or conductive nails. To simplify the description, the following text takes the example of the pole lug 22 and the pole post 12 being electrically connected by welding, and the welding position is the electrical connection position of the pole lug 22 and the pole post 12.

[0147] Specifically, the pole 12 specifically includes a first end wall 12111 and a first side wall 12113, the first end wall 12111 is located on a side of the first side wall 12113 away from the active material coating portion 21, the first end wall 12111 and the first side wall 12113 are surrounded to form a first receiving groove 12110, and the electrical connection position of the pole ear 22 and the pole 12 is located at the first end wall 12111 and / or the first side wall 12113. In other words, the pole ear 22 may be welded to at least one of the first end wall 12111 and the first side wall 12113.

[0148] In the above technical solution, by setting the electrical connection position between the pole tab 22 and the pole post 12 on at least one of the first end wall 12111 and the first side wall 12113, the first receiving groove 12110 not only has the function of accommodating at least part of the pole tab 22, but also the groove wall of the first receiving groove 12110 has the function of realizing electrical connection with the pole tab 22, which can simplify the structure of the pole post 12, facilitate the processing of the pole post 12, and simplify the structure of the pole tab 22, reduce the redundancy of the pole tab 22, and reduce the cost of the pole tab 22. Moreover, by using the groove wall of the first receiving groove 12110 to realize the electrical connection with the pole tab 22, the area where the pole tab 22 is electrically connected to the pole post 12 can be set relatively large, which can not only reduce the difficulty of electrical connection, but also improve the reliability and stability of electrical connection, thereby improving the performance of the battery cell 10.

[0149] In addition, since the electrical connection position between the pole lug 22 and the pole 12 is located in the first receiving groove 12110, it can not only reduce the electrical connection position protruding from the outside of the pole 12 and occupying the space outside the pole 12, but also enable the electrical connection position to be protected by the pole 12, thereby improving the reliability and stability of the electrical connection between the pole lug 22 and the pole 12.

[0150] In addition, in an embodiment of the present application, the first end wall 12111 is constructed as a closed structure without a through hole 12130, so that the first receiving tank 12110 is isolated from the external space of the shell 11, which can reduce the problem of electrolyte in the shell 11 leaking from the first receiving tank 12110.

[0151] Please refer again Figure 5 and Fig.14 In some optional embodiments, the partial shape of the pole ear 22 matches the partial shape of the first end wall 12111, and they are arranged in a close fit and electrically connected, so that the position where the pole ear 22 is electrically connected to the first end wall 12111 extends along the length or width direction of the first end wall 12111. For example, when the first end wall 12111 is a plane, a part of the pole ear 22 can also be a plane and fit to the first end wall 12111, and the fit position is electrically connected, such as by welding. In this way, the area of ​​the electrical connection can be increased, and the reliability and stability of the electrical connection can be improved.

[0152] In addition, when the electrical connection between the pole ear 22 and the first end wall 12111 is welding, since the first end wall 12111 is located on the side of the first receiving groove 12110 away from the active material coating portion 21, the welding operation is convenient, for example, welding can be performed from the side of the pole 12 away from the active material coating portion 21.

[0153] It is worth noting that the shape of the first end wall 12111 is not limited, for example, it can be a flat plate, an arc plate, etc. Among them, when the first end wall 12111 is a flat plate structure, the first end wall 12111 is arranged at an angle with the axial direction R of the pole 12, for example, it can be a flat plate structure perpendicular to the axial direction R of the pole 12, and for example, it can also be an inclined plate structure that is not perpendicular to the axial direction R of the pole 12, but the inclination direction is not limited.

[0154] Of course, in other embodiments of the present application, the position where the pole ear 22 is electrically connected to the first end wall 12111 may not extend along the length or width direction of the first end wall 12111, for example, it may be a plurality of discretely arranged points, for example, the pole ear 22 has a plurality of spaced-apart portions which are respectively welded to the first end wall 12111, which will not be elaborated here.

[0155] Please refer to Fig.15 , Fig.15 A partial cross-sectional schematic diagram of a battery cell 10 provided in some embodiments of the present application. When the pole tab 22 is electrically connected to the first end wall 12111, a first sinking groove 12112 may be provided on the first end wall 12111, and the sinking direction of the first sinking groove 12112 is the direction away from the active material coating portion 21. At least part of the position where the pole tab 22 is electrically connected to the first end wall 12111 is located in the first sinking groove 12112. Exemplarily, at least part of the pole tab 22 may be provided in the first sinking groove 12112 and connected to the portion of the first end wall 12111 used to define the first sinking groove 12112.

[0156] In the above technical scheme, on the one hand, the first sink groove 12112 can be used to realize pre-positioning and limiting of the electrical connection position of the pole ear 22, which is not only conducive to finding the correct position to realize electrical connection and improve production efficiency, but also conducive to improving the stability and reliability of the pole ear 22, and improving the stability and reliability of the battery cell 10 during the charging and discharging process; on the other hand, by arranging the first sink groove 12112 on the first end wall 12111, the local wall thickness of the first end wall 12111 can be locally thinned, which is not only conducive to welding, but also conducive to reducing the weight of the pole column 12 and improving the weight energy density of the battery cell 10.

[0157] Please refer again Fig.14 and Fig.15In the embodiment of the present application, the pole 12 can also be provided with a first groove 126 as required, and the first groove 126 is located on the side of the pole 12 away from the active material coating portion 21, that is, the surface of the side of the pole 12 away from the active material coating portion 21 is the pole outer end face 123, and the notch of the first groove 126 is formed on the pole outer end face 123.

[0158] It can be understood that the first groove 126 is a groove body, and the groove body is a groove-shaped structure with a certain depth. In addition, when the pole 12 is arranged on the upper end wall of the shell 11, and the pole outer end face 123 is the upper surface of the pole 12, the first groove 126 is formed as a first groove 126 with a notch opening upward and a groove wall concave downward (that is, a square concave toward the electrode assembly 2). For another example, when the pole 12 is arranged on the lower end wall of the shell 11, and the pole outer end face 123 is the lower surface of the pole 12, the first groove 126 is formed as a first groove 126 with a notch opening downward and a groove wall concave upward (that is, a square concave away from the electrode assembly 2).

[0159] In the above technical solution, on the one hand, since the pole 12 is provided with the first groove 126, the weight of the pole 12 can be further reduced, so as to improve the weight energy density of the battery cell 10 and the battery 100; on the other hand, the first groove 126 is located on the outer side of the pole 12, that is, it is open to the side of the pole 12 away from the inside of the shell 11, and the first groove 126 can be used to accommodate or install structural components of the battery 100 that electrically connect the various battery cells 10, so as to make full use of the space inside the pole 12 and improve the space utilization and volume energy density of the battery 100.

[0160] In addition, since the pole 12 has both the first receiving groove 12110 and the first groove 126, the first groove 126 is located on the side of the first receiving groove 12110 away from the active material coating portion 21, and the first groove 126 is open in the direction away from the first receiving groove 12110, which is convenient for laser welding the pole ear 22 and the first end wall 12111 from the outside of the pole 12, that is, the side of the pole 12 away from the active material coating portion 21, through the first groove 126, and it is convenient to realize the electrical connection between the pole ear 22 and the pole 12 through external welding. That is to say, through the above-mentioned structural setting, it is convenient to perform external welding on the pole 12 and the pole ear 22 through the first groove 126, which is convenient for processing and manufacturing of the battery cell 10, and can save the processing and manufacturing costs.

[0161] Furthermore, in order to conveniently and effectively weld the tab 22 to the slot wall of the first receiving slot 12110 through the first groove 126 and improve the welding reliability of the tab 22 to the slot wall of the first receiving slot 12110, in the embodiment of the present application, the portion between the first groove 126 and the first receiving slot 12110 can be laser welded to the tab 22, that is, Fig.15 The spacer 127 shown is laser welded with the pole tab 22 to achieve electrical connection between the electrode assembly 2 and the pole 12. The thickness of the spacer 127 of the pole 12 located between the first groove 126 and the first receiving groove 12110 is relatively thin, and the spacer 127 isolates the first groove 126 and the first receiving groove 12110. The side wall of the spacer 127 close to the active material coating portion 21 can be used as the first end wall 12111. When the pole tab 22 needs to be welded with the first end wall 12111, since the thickness of the spacer 127 is relatively thin, it is convenient to achieve welding of the pole tab 22 and the first end wall 12111 through the first groove 126, thereby improving the convenience and reliability of welding.

[0162] Please refer again Fig.14 Furthermore, the battery cell 10 may also include a slot cover 7, which is provided on the pole 12 and covers the notch of the first groove 126. In the above technical solution, by providing the slot cover 7 that covers the first groove 126, the pole 12 can be indirectly electrically connected to the current collector through the slot cover 7, and the position and structure of the slot cover 7 can be set to make the electrical connection between the slot cover 7 and the current collector more convenient and the electrical connection area larger. Therefore, by providing the slot cover 7, the electrical connection between adjacent battery cells 10 in the battery 100 can be facilitated, and since the position where the battery cells 10 are electrically connected to the battery cells 10 is located at the slot cover 7, the electrical connection position with the pole lug 22 and the pole 12 can be separated by the first groove 126, and there is less interference between the two, which can further improve the stability and reliability of the battery cell 10.

[0163] For example, please refer to Fig.16 , Fig.16 A partial cross-sectional schematic diagram of a battery cell 10 provided for some embodiments of the present application, wherein the accommodating portion 121 may also be configured to include a second accommodating groove 12120, the surface of the pole 12 away from the active material coating portion 21 is the pole outer end face 123, the notch of the second accommodating groove 12120 is formed on the pole outer end face 123, the second accommodating groove 12120 is connected to the interior of the shell 11 through a through hole 12130, the pole ear 22 is penetrated through the through hole 12130 and is at least partially accommodated in the second accommodating groove 12120.

[0164] It can be understood that the second receiving groove 12120 is a groove body, and the groove body is a groove-shaped structure with a certain depth. For example, when the pole 12 is arranged on the upper end wall of the housing 11, and the pole outer end surface 123 is the upper surface of the pole 12, the second receiving groove 12120 is formed as a receiving groove with a groove opening upward and a groove wall concave downward. For another example, when the pole 12 is arranged on the lower end wall of the housing 11, and the pole outer end surface 123 is the lower surface of the pole 12, the second receiving groove 12120 is formed as a receiving groove with a groove opening downward and a groove wall concave upward.

[0165] In the above technical solution, please refer to Fig.16 On the one hand, the pole 12 is provided with a second receiving groove 12120, which can reduce the weight of the pole 12 to a certain extent, so as to improve the weight energy density of the battery cell 10 and the battery 100; on the other hand, since the notch of the second receiving groove 12120 is formed on the outer end surface 123 of the pole, and the outer end surface 123 of the pole is the surface of the pole 12 away from the active material coating portion 21, the second receiving groove 12120 can be opened in the direction away from the active material coating portion 21. In this way, when at least part of the pole lug 22 is accommodated in the second receiving groove 12120, the pole lug 22 can be easily stored and sorted through the notch of the second receiving groove 12120, and the electrical connection operation between the pole lug 22 and the pole 12 can be easily achieved through the notch of the second receiving groove 12120, etc., thereby reducing the production difficulty of the battery cell 10 and improving the production efficiency of the battery cell 10.

[0166] At the same time, because the second receiving groove 12120 can be connected with the interior of the shell 11 through the perforation 12130, the second receiving groove 12120 can also be used as a buffer and temporary storage structure for the electrolyte, so that more electrolyte can be accommodated in the shell 11. Since the electrolyte will be consumed during the charging and discharging process of the battery cell 10, when there is more electrolyte, the service life of the battery cell 10 can be extended; and because the second receiving groove 12120 can be connected with the interior of the shell 11 through the perforation 12130, the second receiving groove 12120 can also be used as a receiving and buffer structure for gas production inside the electrode assembly 2, thereby reducing the expansion of the battery cell 10 and improving the reliability and stability of the battery cell 10.

[0167] It is worth noting that when the accommodating portion 121 has a second accommodating groove 12120, and the pole lug 22 is provided in the through hole 12130 and is at least partially accommodated in the second accommodating groove 12120, the electrical connection position of the pole lug 22 and the pole 12 is not limited. Exemplarily, when the pole lug 22 is provided in the through hole 12130 and is at least partially accommodated in the second accommodating groove 12120, in an embodiment of the present application, the electrical connection position of the pole lug 22 and the pole 12 is located at the hole wall of the through hole 12130 formed by the pole 12.

[0168] In the above technical solution, by setting the electrical connection position between the pole lug 22 and the pole post 12 on the hole wall of the through-hole 12130, it is convenient to perform electrical connection operation between the pole lug 22 and the pole post 12 through the second receiving groove 12120, and when the electrical connection area between the pole lug 22 and the pole post 12 is large, the electrical connection between the pole lug 22 and the pole post 12 can be used to realize the sealing of the through-hole 12130, so as to save sealing costs, reduce electrolyte leakage, and save sealing parts.

[0169] Specifically, the electrode ear 22 can be welded to the hole wall of the through hole 12130 at the position where the through hole 12130 is connected to the second accommodating groove 12120, which is convenient for operation. In addition, the welding mark can be controlled to seal the through hole 12130 using the welding mark and the electrode ear 22, so as to improve the problem of electrolyte leakage from the through hole 12130 in the shell 11.

[0170] As another example, when the pole tab 22 is passed through the through hole 12130 and at least partially accommodated in the second accommodating groove 12120, in some other embodiments of the present application, the electrical connection position between the pole tab 22 and the pole 12 can also be located on the groove wall of the second accommodating groove 12120 formed by the pole 12. Thus, the electrical connection operation is facilitated. For example, when the pole tab 22 and the groove wall of the second accommodating groove 12120 formed by the pole 12 are welded, the conductive particles generated by the welding can be prevented from entering the housing 11, causing a short circuit and other problems.

[0171] Please refer again Fig.16 The pole 12 includes a second end wall 12121 and a second side wall 12123, the second end wall 12121 is located on the side of the second side wall 12123 close to the active material coating portion 21, the second end wall 12121 and the second side wall 12123 are arranged to form a second accommodating groove 12120, the through hole 12130 is opened on the second end wall 12121, and the electrical connection position between the pole ear 22 and the pole 12 is located on the second end wall 12121 and / or on the second side wall 12123.

[0172] More specifically, the tab 22 and the pole 12 can be electrically connected by welding, so the welding position is the electrical connection position of the tab 22 and the pole 12. In other embodiments of the present application, the tab 22 and the pole 12 can also be electrically connected by other methods instead of welding, such as by providing conductive glue or conductive nails, which will not be described here.

[0173] To simplify the description, the following description takes the case where the pole tab 22 is welded to the pole post 12 to form an electrical connection, and the welding position is the electrical connection position between the pole tab 22 and the pole post 12. For example, in some embodiments, the electrical connection position between the pole tab 22 and the pole post 12 is located at the second end wall 12121 and / or the second side wall 12123, and the pole tab 22 may be welded to at least one of the second end wall 12121 and the second side wall 12123.

[0174] In the above technical solution, by setting the electrical connection position between the pole tab 22 and the pole 12 on at least one of the second end wall 12121 and the second side wall 12123, the second receiving groove 12120 not only has the function of accommodating at least part of the pole tab 22, but also the groove wall of the second receiving groove 12120 has the function of realizing electrical connection with the pole tab 22, which can simplify the structure of the pole 12 and facilitate the processing of the pole 12. In addition, since the through hole 12130 is provided on the second end wall 12121, it is convenient for the pole tab 22 to extend into the second receiving groove 12120 through the through hole 12130, which can simplify the structure of the pole tab 22, reduce the redundancy of the pole tab 22, and reduce the cost of the pole tab 22. Furthermore, the opening direction of the slot of the second receiving groove 12120 makes it easy to electrically connect the pole lug 22 to the slot wall of the second receiving groove 12120 through the slot of the second receiving groove 12120, thereby reducing the difficulty of electrical connection. Moreover, by utilizing the slot wall of the second receiving groove 12120 to achieve electrical connection with the pole lug 22, the area where the pole lug 22 is electrically connected to the pole 12 can be relatively large, thereby improving the reliability and stability of the electrical connection, thereby improving the performance of the battery cell 10.

[0175] In addition, since the electrical connection position between the pole lug 22 and the pole 12 is located in the second receiving groove 12120, it can not only reduce the electrical connection position protruding from the outside of the pole 12 and occupying the space outside the pole 12, but also enable the electrical connection position to be protected by the pole 12, thereby improving the reliability and stability of the electrical connection between the pole lug 22 and the pole 12.

[0176] Please refer again Fig.16 In some embodiments, the partial shape of the tab 22 matches the partial shape of the second end wall 12121, and they are arranged in a fit and electrically connected, so that the position where the tab 22 is electrically connected to the second end wall 12121 extends along the length or width direction of the second end wall 12121. For example, when the second end wall 12121 is a plane, a part of the tab 22 can also be a plane and fit to the second end wall 12121, and the fit position is electrically connected, such as by welding. In this way, the area of ​​the electrical connection can be increased, and the reliability and stability of the electrical connection can be improved.

[0177] It is worth noting that the shape of the second end wall 12121 is not limited, for example, it can be a flat plate or an arc plate structure. When the second end wall 12121 is a flat plate structure, the second end wall 12121 is arranged at an angle with the axial direction R of the pole 12, for example, it can be a flat plate structure perpendicular to the axial direction R of the pole 12, or it can also be an inclined flat plate structure that is not perpendicular to the axial direction R of the pole 12, but the inclination direction is not limited.

[0178] For example, please refer again to Fig.16When the second end wall 12121 is in a flat plate structure, the angle θ between the second end wall 12121 and the axial direction R of the pole 12 is equal to 90°, that is, along the direction from the through hole 12130 to the second side wall 12123, the second end wall 12121 and the active material coating portion 21 are equidistant. This facilitates welding of the pole ear 22 and the second end wall 12121.

[0179] For another example, the angle θ between the second end wall 12121 and the axial direction R of the pole 12 is greater than 90°, that is, along the direction from the through hole 12130 to the second side wall 12123, the second end wall 12121 extends obliquely toward the direction close to the active material coating portion 21. As a result, the extension distance of the pole lug 22 along the second end wall 12121 can be increased to increase the reliability of the electrical connection. Exemplarily, the angle θ between the second end wall 12121 and the axial direction R of the pole 12 can be 90°-145°, such as 100°, 110°, 120°, 130°, 140°, etc., which can make the second end wall 12121 easy to process and convenient for electrical connection with the pole lug 22, and can make full use of the space in the pole 12 to accommodate the pole lug 22.

[0180] For another example, the angle θ between the second end wall 12121 and the axial direction R of the pole 12 is less than 90°, that is, along the direction from the through hole 12130 to the second side wall 12123 , the second end wall 12121 extends obliquely away from the active material coating portion 21 .

[0181] Thus, the extension distance of the pole lug 22 along the second end wall 12121 can be increased to increase the reliability of the electrical connection. Exemplarily, the angle θ between the second end wall 12121 and the axial direction R of the pole 12 can be 45°-90°, such as 50°, 60°, 70°, 80°, etc., which can make the second end wall 12121 easy to process and convenient for electrical connection with the pole lug 22, and can make full use of the space in the pole 12 to accommodate the pole lug 22.

[0182] Of course, the present application is not limited to this. In other embodiments of the present application, the position where the pole ear 22 is electrically connected to the second end wall 12121 may not extend along the length or width direction of the second end wall 12121, and it may also be a plurality of discretely arranged points. For example, the pole ear 22 has a plurality of spaced-apart portions that are respectively welded to the second end wall 12121, which will not be elaborated here.

[0183] Please refer again Fig.16 , and further refer to Fig.17 , Fig.17A partial cross-sectional schematic diagram of a battery cell 10 provided in some embodiments of the present application. Regardless of the specific value of the angle θ between the second end wall 12121 and the axial direction R of the pole 12, in the embodiments of the present application, when the pole tab 22 is electrically connected to the second end wall 12121, a second sinking groove 12122 can be provided on the second end wall 12121 as required, and the second sinking groove 12122 is a groove formed by a part of the second end wall 12121 sinking toward one end close to the active material coating portion 21. The position where the pole tab 22 is electrically connected to the second end wall 12121 is at least partially located in the second sinking groove 12122.

[0184] In the above technical solution, the portion of the pole lug 22 located in the second groove 12122 is set to match the shape of the second groove 12122, and is fitted to achieve electrical connection. The second groove 12122 can be used to pre-position and limit the electrical connection position of the pole lug 22, which is conducive to finding the correct position to achieve electrical connection, improve production efficiency, and improve the stability and reliability of the electrical connection position, so as to improve the reliability and stability of the charging and discharging operations of the battery cell 10.

[0185] Please refer again Fig.17 In the embodiment of the present application, the connection method between the pole 12 and the housing 11 is not limited, for example, it can be welding or riveting. For example, when the two are matched by riveting, the housing 11 has a mounting hole 113, and the pole 12 is riveted and installed at the mounting hole 113. Of course, it can be understood that when the two are matched by welding or other methods, the housing 11 can also be provided with a mounting hole 113, and the pole 12 is installed at the mounting hole 113.

[0186] Optionally, please refer again to Fig.16 The second accommodating groove 12120 can be set corresponding to the position of the mounting hole 113, or in other words, on the projection plane perpendicular to the axial direction R of the pole 12, the orthographic projection of the second accommodating groove 12120 is located within the orthographic projection range of the mounting hole 113, so that the second accommodating groove 12120 can have a larger depth to accommodate more pole ears 22, thereby reducing the space occupied by the pole ears 22 in the shell 11 to a greater extent.

[0187] In some embodiments, please refer again to Fig.16 When the housing 11 has a mounting hole 113 and the pole 12 is installed in the mounting hole 113, along the axial direction R of the pole 12, the depth H3 of the second accommodating groove 12120 is greater than or equal to the minimum distance H4 from the outer end surface 123 of the pole to the mounting hole 113.

[0188] It should be noted that the specific shape of the second receiving groove 12120 is not limited, and can be a regular shape or an irregular shape, such as a cylindrical groove with a rectangular, elliptical, or racetrack-shaped cross section, or a trapezoidal groove with a rectangular cross section and a gradually changing cross-sectional size, or a hemispherical groove with a circular cross section and a gradually changing cross-sectional size, or a hemispherical groove with an elliptical cross section and a gradually changing cross-sectional size, etc. It is worth noting that the racetrack shape described herein refers to a shape in which the two short sides of a rectangle are replaced by convex curves.

[0189] Therefore, the depth H3 of the second receiving groove 12120 refers to: the maximum depth of the second receiving groove 12120 along the axial direction R of the pole 12. Since the depth H3 of the second receiving groove 12120 is greater than or equal to the minimum distance H4 from the outer end surface 123 of the pole to the mounting hole 113 in the axial direction R of the pole 12, the volume of the pole 12 can be fully utilized, so that the second receiving groove 12120 has a larger depth, which is conducive to accommodating more pole tabs 22, and further can reduce the space occupied by the pole tabs 22 in the shell 11 to a greater extent, further improve the energy density of the battery cell 10, and further reduce the redundancy of the pole tabs 22 in the shell 11; at the same time, since the second receiving groove 12120 has a larger depth, it can also accommodate the gas production of the electrode assembly 2, improve the reliability and stability of the battery cell 10, and can also accommodate more electrolyte to increase the service life of the battery cell 10.

[0190] Please refer to Fig.17 , and further refer to Fig.18 , Fig.18 A partial cross-sectional schematic diagram of a battery cell 10 provided in some embodiments of the present application. In the embodiments of the present application, when the receiving portion 121 has the second receiving groove 12120 of any of the above embodiments, optionally, the battery cell 10 may further include a cover plate 13, the cover plate 13 cooperates with the pole 12 and closes the notch of the second receiving groove 12120, and the cover plate 13 is electrically connected to the pole 12.

[0191] In the above technical solution, by setting the cover plate 13 to close the notch of the second receiving groove 12120, the leakage of the electrolyte in the shell 11 from the notch of the second receiving groove 12120 can be reduced, and because the cover plate 13 closes the notch of the second receiving groove 12120 and is electrically connected to the pole 12, the cover plate 13 can be used to easily realize the indirect electrical connection between the pole 12 and the busbar component, and it is beneficial to increase the connection area of ​​the electrical connection, thereby helping to reduce the resistance of the electrical connection.

[0192] It is worth noting that the matching mode and matching position of the cover plate 13 and the pole 12 are not limited, as long as the cover plate 13 can close the notch of the second receiving groove 12120. For example, in some embodiments, the cover plate 13 can be welded to the pole 12. During processing, the pole ear 22 can first pass through the through hole 12130 and be welded to the groove wall of the second receiving groove 12120, and then the cover plate 13 and the pole 12 are welded to close the notch of the second receiving groove 12120.

[0193] It should also be noted that the specific structure of the cover plate 13 is not limited. For example, in some optional embodiments, please refer to Fig.18 The cover plate 13 includes a first conductive member 131 and a second conductive member 132 made of different materials. The first conductive member 131 cooperates with and is electrically connected to the pole 12 , and the second conductive member 132 cooperates with and is electrically connected to the first conductive member 131 .

[0194] In the above technical solution, the cover plate 13 is set to a composite form, and the first conductive member 131 is set to be the same material as the pole 12, so as to facilitate the electrical connection between the first conductive member 131 and the pole 12, for example, the first conductive member 131 can be easily connected to the pole 12 reliably and stably by welding. And because the second conductive member 132 is made of a different material from the first conductive member 131, it is convenient to use the second conductive member 132 to electrically connect with a busbar component whose material is different from that of the pole 12, for example, the second conductive member 132 can be easily connected to a busbar component whose material is the same as that of the second conductive member 132 reliably and stably by welding.

[0195] For example, when the pole 12 is a negative pole 12, the pole 12 is a copper pole, and the current collecting component is an aluminum sheet, at this time, the first conductive member 131 can be set to copper material, and the second conductive member 132 can be set to aluminum material. At this time, the pole 12 and the first conductive member 131 are made of the same material and can be effectively welded, and the second conductive member 132 and the current collecting component are made of the same material and can be effectively welded, so that the pole 12 can be effectively connected to the current collecting component indirectly through the cover plate 13. Moreover, the welding of the pole 12 and the first conductive member 131 is copper material and copper material, which has good fluidity and is not easy to crack, which is conducive to improving the sealing effect of the welding point.

[0196] Please refer again Fig.18In some optional examples, the first conductive member 131 is located between the second containing groove 12120 and the second conductive member 132. In the above technical solution, since the first conductive member 131 is located between the second containing groove 12120 and the second conductive member 132, the second containing groove 12120 and the second conductive member 132 can be separated, so that when the electrolyte in the housing 11 enters the second containing groove 12120 from the through hole 12130, the first conductive member 131 can be used to reduce the contact between the electrolyte and the second conductive member 132, thereby solving the problem of corrosion of the second conductive member 132 by the electrolyte.

[0197] It is worth noting that the matching method of the first conductive member 131 and the second conductive member 132 is not limited. Fig.18 The first conductive member 131 has a second groove 1311, and the second conductive member 132 is embedded in the second groove 1311. The notch of the second groove 1311 is formed on the surface of the first conductive member 131 away from the second receiving groove 12120, so that the second conductive member 132 is exposed from the notch of the second groove 1311. Alternatively, in other embodiments, the connection method between the first conductive member 131 and the second conductive member 132 can also be fastening connection, clamping, etc.

[0198] It should also be noted that the “exposed” of the second conductive member 132 being exposed from the notch of the second groove 1311 means that the first conductive member 131 does not block the second conductive member 132 at the notch position of the second groove 1311, and the second conductive member 132 is not required to protrude from the notch of the second groove 1311. For example, the second conductive member 132 may be flush with the surface of the first conductive member 131 on the side away from the second accommodating groove 12120, or the second conductive member 132 may protrude from the surface of the first conductive member 131 on the side away from the second accommodating groove 12120.

[0199] In the above technical solution, on the one hand, by embedding the second conductive member 132 in the first conductive member 131, the difficulty of assembling the first conductive member 131 and the second conductive member 132 can be reduced, the stability and convenience of the cooperation between the first conductive member 131 and the second conductive member 132 can be improved, and the thickness of the cover plate 13 can be reduced, and the space occupied by the cover plate 13 can be reduced to improve the space utilization of the battery cell 10. On the other hand. In addition, since the second conductive member 132 can be exposed from the surface of the first conductive member 131 away from the second receiving groove 12120 through the notch of the second groove 1311, it is conducive to realizing the electrical connection between the second conductive member 132 and the current collecting component outside the pole 12.

[0200] In addition, since the notch of the second groove 1311 is formed on the surface of the first conductive member 131 on the side away from the second receiving groove 12120, it means that the second groove 1311 is open in the direction away from the active material coating portion 21, so that the portion of the groove wall of the first conductive member 131 used to define the second groove 1311 is located between the second receiving groove 12120 and the second conductive member 132 to separate the second receiving groove 12120 from the second conductive member 132, thereby preventing the electrolyte entering the second groove 1311 from contacting the second conductive member 132 and reducing leakage of the electrolyte.

[0201] Of course, in other embodiments, the cover plate 13 may not be a composite form composed of multiple materials. For example, in other embodiments of the present application, the cover plate 13 as a whole may be set to a non-composite form made of the same material, such as for adapting to the positive electrode column 12, which will not be elaborated here.

[0202] Please refer again Fig.18 , the cover plate 13 is also embedded in the notch of the second receiving groove 12120. In the above technical solution, by embedding the cover plate 13 in the second receiving groove 12120, the difficulty of assembling the cover plate 13 and the pole 12 can be reduced, the assembly stability of the cover plate 13 and the pole 12, as well as the reliability and convenience of the connection can be improved, and the space occupied by the cover plate 13 outside the pole 12 can be reduced. Moreover, since the cover plate 13 is embedded in the notch of the second receiving groove 12120, there can be sufficient space in the second receiving groove 12120 to accommodate the pole lug 22.

[0203] Of course, in other embodiments of the present application, the cooperation between the cover plate 13 and the pole 12 is not limited to being embedded in the second receiving groove 12120. The cover plate 13 can also be directly covered on the outside of the pole 12, that is, directly covered at the notch of the second receiving groove 12120, so as to facilitate the cooperation with the convergence component of the battery 100, which is not limited in this embodiment.

[0204] The present application provides a battery 100, which includes the battery cell 10 in the above embodiment. In the technical solution of the embodiment of the present application, by using the above battery cell 10, the overcurrent temperature rise can be reduced, the probability of thermal runaway can be reduced, and the reliability of the battery 100 can be improved.

[0205] The present application provides an electric device 1000, which includes the battery 100 in the above embodiment. In the technical solution of the embodiment of the present application, the reliability of the electric device 1000 can be improved by using the above battery 100.

[0206] Please refer to Fig.19 , Fig.19The present application provides a method for preparing a battery cell, comprising the following steps:

[0207] S1. Provide a shell and an electrode assembly;

[0208] The shell 11 is provided with a pole 12 , and the electrode assembly 2 includes an active material coating portion 21 and a pole tab 22 , and the pole tab 22 is connected to the active material coating portion 21 .

[0209] S2, installing the electrode assembly into the housing;

[0210] S3, welding the electrode lug and the electrode column to form a first weld and a second weld;

[0211] The second weld 232 is located on one side of the first weld 231 in the width direction, and the second weld 232 partially overlaps with the first weld 231 , and the maximum thickness of the first weld 231 is less than the maximum thickness of the second weld 232 .

[0212] In the technical solution of the embodiment of the present application, since the edge of the second weld 232 is prone to cracks and affects the connection strength of the weld mark 23, a first weld 231 is formed on one side in the width direction of the second weld 232. The first weld 231 can be used to effectively reduce the probability of welding cracks in the multi-layer tab sheets of the tab 22 and reduce over-current temperature rise, thereby reducing the probability of thermal runaway of the electrode assembly 2 due to excessive temperature rise. On the other hand, the peeling strength of the weld mark 23 on the tab 22 can be increased, thereby significantly improving the reliability of the battery cell 10.

[0213] In some embodiments, second weld 232 is formed after first weld 231 .

[0214] Specifically, in the process of welding the pole ear 22 to the pole 12, the following Figure 6 and Figure 7 The first weld 231 shown, the first weld 231 serves as a base weld, and the maximum thickness of the first weld 231 is relatively small, that is, the depth of the molten pool of the first weld 231 is relatively small, that is, the depth of the molten pool of the base weld is relatively small, and the required welding power is relatively small, which can greatly reduce the heat input in the initial stage of welding, thereby reducing the thermal shrinkage of the molten pool of the base weld and reducing the risk of fracture of the multi-layer pole ear sheets of the pole ear 22.

[0215] After forming the first weld 231, the Figure 8 and Fig. 9The second weld 232 shown is used as the main weld. The maximum thickness of the second weld 232 is large, that is, the depth of the molten pool of the second weld 232 is large, that is, the depth of the molten pool of the main weld is large, and the required welding power is large. Specifically, when welding the main weld, the edge of the molten pool of the main weld falls into the molten pool of the base weld that has been solidified into a solid structure. At this time, the shrinkage of the molten pool of the main weld will not affect the multi-layer pole tab sheet at the base molten pool, which can reduce the proportion of thermal cracks in the multi-layer pole tab sheet, and the welding of the main weld here can be equivalent to the welding of the solid adapter sheet in the related art, which can improve the reliability of the electrical connection between the pole 12 and the pole tab 22.

[0216] In the above technical scheme, in the process of welding the pole lug 22 to the pole column 12, the first weld 231 is formed first and then the second weld 232 is formed. Since the maximum thickness of the first weld 231 formed first is smaller than the maximum thickness of the second weld 232 formed later, the welding power when forming the first weld 231 is smaller than the welding power when forming the second weld 232. The gradual transition from low-power welding to high-power welding can, on the one hand, effectively reduce the probability of welding cracks in the multi-layer pole lug sheets of the pole lug 22 and reduce the over-current temperature rise, thereby reducing the probability of thermal runaway of the electrode assembly 2 due to excessive temperature rise. On the other hand, the peeling strength of the weld mark 23 on the pole lug 22 can be increased, thereby significantly improving the reliability of the battery cell 10.

[0217] In some embodiments, when welding the pole lug 22 and the pole 12 , a third weld 233 is also formed, and the third weld 233 is formed after the first weld 231 ;

[0218] Specifically, in the process of welding the pole ear 22 to the pole 12, it can be that firstly forming Figure 6 and Figure 7 The first weld 231 shown in FIG. Figure 8 and Fig. 9 The second weld 232 shown in FIG. Fig.11 and Fig.10 The third weld 233 shown in FIG. 1 may also be formed by first forming Figure 6 and Figure 7 The first weld 231 shown in FIG. Fig.11 and Fig.10 The third weld 233 shown finally forms Figure 8 and Fig. 9 The second weld 232 shown in FIG. 1 may also be formed by first forming Figure 6 and Figure 7 The first weld 231 shown in FIG. Figure 8 and Fig. 9 The second weld 232 shown, Fig.11 and Fig.10A third weld 233 is shown.

[0219] The third weld 233 and the second weld 232 are respectively located on opposite sides of the first weld 231 in the width direction, and the third weld 233 partially overlaps with the first weld 231 . The thickness of the third weld 233 is less than the thickness of the tab 22 .

[0220] The third weld 233 is used as a repair weld, and the maximum thickness of the repair weld is small, that is, the molten pool depth of the repair weld is small, and the required welding power is small, which can reduce the heat input during the welding process, thereby reducing the thermal shrinkage of the molten pool of the repair weld and reducing the risk of fracture of the multi-layer pole tab sheets of the pole tab 22.

[0221] Therefore, in the above technical solution, by providing the third weld 233, on the one hand, the welding microcracks of the multi-layer pole tab sheets at the edge of the first weld 231 can be repaired, and on the other hand, the welding connection strength between the pole tab 22 and the pole 12 can be greatly improved.

[0222] According to some embodiments of the present application, a method for preparing a battery cell 10 is provided.

[0223] In the first step, the tabs 22 of the electrode assembly 2 are paired. After the tabs 22 are paired, multiple tab sheets of the tabs 22 are pre-welded together by ultrasonic welding to reduce the interlayer gap and form the fluffy tabs 22 into a plate with a certain rigidity.

[0224] The second step is to assemble the pole lug 22 on the pole 12. The pole lug 22 can be pressed by a tool to fit on the pole 12, and then welded to form a first weld 231. The welding power for forming the first weld 231 needs to be just enough to weld through the multi-layer pole lug sheets of the pole lug 22.

[0225] Step 3: welding the second weld 232. The welding position of the second weld 232 requires that the edge of the second weld 232 falls within the molten pool of the first weld 231.

[0226] The fourth step is welding the third weld 233 . The third weld 233 is located at a side edge of the first weld 231 away from the second weld 232 . The depth of the molten pool of the third weld 233 is 50% to 80% of the thickness of the tab 22 after pre-welding.

[0227] According to some embodiments of the present application, a battery cell 10 is provided.

[0228] The battery cell 10 includes a shell 11 and an electrode assembly 2, the shell 11 includes a shell cover 112 and a shell body 111 with an opening 1110, the shell cover 112 covers the opening 1110 of the shell body 111, and a pole 12 is provided on the wall of the shell body 111 opposite to the opening 1110, the electrode assembly 2 includes an active material coating portion and a pole ear 22, the pole ear 22 is connected to the active material coating portion 21, the active material coating portion 21 of the electrode assembly 2 is arranged in the shell 11, and the pole ear 22 of the electrode assembly 2 is welded to the pole 12 to form a weld mark.

[0229] The weld mark 23 has a length direction and a width direction. The second weld 232 is located in the middle of the weld mark 23 in its width direction. The first welds 231 are respectively provided on both sides of the second weld 232 in the width direction, and each first weld 231 and the second weld 232 overlap in the width direction of the weld mark 23. A third weld 233 is provided on the side of each first weld 231 away from the second weld 232, and each second weld 232 and the corresponding third weld 233 overlap in the width direction of the weld mark 23, so that the molten pool of the weld mark 23 roughly forms a "T" shape.

[0230] Among them, the ratio of the maximum thickness H1 of the first weld 231 to the thickness H of the tab 22 is 0.8-1, the width L1 of the first weld 231 is 0.5mm-3.0mm, the maximum thickness H2 of the second weld 232 is greater than the thickness H of the tab 22, the width L2 of the second weld 232 is greater than twice the width L1 of the first weld 231, the ratio of the maximum thickness H3 of the third weld 233 to the thickness H of the tab 22 is 0.5-0.8, and the width L3 of the third weld 233 is 0.5mm-2.0mm.

[0231] In the above technical solution, after welding is completed, the molten pool of the weld mark 23 formed by the first weld 231, the second weld 232 and the third weld 233 is T-shaped. When the pole tab 22 is peeled off or pulled, the peeling force of the multi-layer pole tab sheet connected to the molten pool of the third weld 233 can be converted into shear force, thereby greatly improving the welding connection strength between the pole tab 22 and the pole 12.

[0232] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A shell body provided with a pole; An electrode assembly is disposed in the housing, the electrode assembly comprising an active material coating portion and a pole ear connected to the active material coating portion, the pole ear is welded to the pole and forms a weld mark; The weld mark includes a first weld and a second weld, the second weld is located on one side of the first weld in a width direction and partially overlaps with the first weld, and the maximum thickness of the first weld is less than the maximum thickness of the second weld.

2. The battery cell according to claim 1, characterized in that: The ratio of the maximum thickness of the first weld to the thickness of the tab is 0.8-1.

2.

3. The battery cell according to claim 2, characterized in that: The ratio of the maximum thickness of the first weld to the thickness of the tab is 0.8-1.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The width of the first weld is 0.5 mm-3.0 mm.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The maximum thickness of the second weld is greater than the thickness of the pole tab, so that the second weld penetrates the pole tab and the first weld along the thickness direction thereof and extends into the pole column.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The width of the second weld is greater than twice the width of the first weld.

7. The battery cell according to any one of claims 1 to 6, characterized in that: The weld mark also includes a third weld, the third weld and the second weld are respectively located on opposite sides of the first weld in the width direction, and the third weld partially overlaps the first weld, and the maximum thickness of the third weld is less than the thickness of the tab.

8. The battery cell according to claim 7, characterized in that: The ratio of the maximum thickness of the third weld to the thickness of the tab is 0.5-0.

8.

9. The battery cell according to claim 7 or 8, characterized in that: The maximum thickness of the third weld is less than the maximum thickness of the first weld.

10. The battery cell according to any one of claims 7 to 9, characterized in that: The width of the third weld is 0.5 mm-2.0 mm.

11. The battery cell according to any one of claims 7 to 10, characterized in that: Each of the first weld, the second weld and the third weld includes a plurality of weld sections, and the plurality of weld sections are arranged and connected in a length direction of the respective welds.

12. The battery cell according to any one of claims 7 to 11, characterized in that: The first welds are disposed on opposite sides of the second weld in a width direction, and the second weld and the third weld are disposed on opposite sides of each first weld in a width direction, respectively.

13. The battery cell according to any one of claims 1 to 12, characterized in that: The pole is provided with a receiving portion, and at least a portion of the pole lug extends into the receiving portion and is welded to the pole.

14. The battery cell according to claim 13, characterized in that: The accommodating portion includes a first accommodating groove, the surface of the pole facing the active material coating portion is the inner end face of the pole, the notch of the first accommodating groove is formed on the inner end face of the pole, and at least part of the pole ear is accommodated in the first accommodating groove.

15. The battery cell according to claim 13, characterized in that: The accommodating portion includes a second accommodating groove, the surface of the pole away from the active material coating portion is the outer end face of the pole, the notch of the second accommodating groove is formed on the outer end face of the pole, the second accommodating groove is connected to the interior of the shell through a through hole, the pole ear is penetrated through the through hole and is at least partially accommodated in the second accommodating groove.

16. The battery cell according to any one of claims 1 to 15, characterized in that: The shell comprises a shell cover and a shell body with an opening, the shell cover covers the opening, and the pole is arranged on the shell cover and / or the wall of the shell body opposite to the opening.

17. A battery, characterized in that: The invention comprises a battery cell according to any one of claims 1 to 16.

18. An electrical device, characterized in that: Comprising a battery according to claim 17.

19. A method for preparing a battery monomer, characterized in that: The following steps are involved: A shell and an electrode assembly are provided, wherein the shell is provided with an electrode column, and the electrode assembly includes an active material coating portion and an electrode ear connected to the active material coating portion; Installing the electrode assembly into the housing; The pole lug and the pole are welded to form a first weld and a second weld, wherein the second weld is located on one side of the first weld in a width direction and partially overlaps the first weld, and the maximum thickness of the first weld is less than the maximum thickness of the second weld.

20. The method for preparing a battery cell according to claim 19, characterized in that: The second weld is formed after the first weld.

21. The method for preparing a battery monomer according to claim 19, characterized in that: When welding the pole lug and the pole, a third weld is formed, and the third weld is formed after the first weld; The third weld and the second weld are respectively located on opposite sides of the first weld in a width direction, and the third weld partially overlaps with the first weld. The thickness of the third weld is smaller than the thickness of the tab.

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