Single battery

Abstract

The invention discloses a single battery, and belongs to the technical field of batteries. The single battery comprises a cover plate assembly, and the cover plate assembly comprises a cover plate body, a first pole and a second pole; the cover plate body is provided with an assembling hole. The first pole comprises a penetrating part and a first main body part, the first main body part is arranged on one side of the cover plate body along the thickness direction, the penetrating part is connected with the first main body part, and at least part of the penetrating part is convexly arranged in the assembly hole; the second pole comprises a connecting part and a second main body part, the second main body part is arranged on the side, away from the first main body part, of the cover plate body, the connecting part is connected with the first main body part, at least part of the connecting part is arranged in the assembly hole in a protruding mode and abuts against the first main body part, a through hole is formed in the connecting part, and the penetrating part is arranged in the through hole in a penetrating mode; the penetrating part and the connecting part are welded to form a first welding part; and the first main body part is welded with the connecting part to form a second welding part. The connection stability is improved through a double welding structure, and the sealing performance of the single battery is improved.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a single cell battery. Background Art

[0002] Lithium batteries are composed of a shell, a battery cell inside the shell, and a cover. The cover structure of lithium batteries is a very important part of the structure. The cover structure is provided with poles for electrically connecting the battery cell and connecting to the external circuit.

[0003] The lithium battery cover is provided with a pole structure, including an upper pole and a lower pole, which are fixed by welding to achieve the joint clamping of the cover body, sealing ring and insulating parts to ensure that its sealing performance, insulation performance, durability and other series of performances meet the corresponding standards during the later use. However, the traditional welding method has insufficient structural strength, which affects the sealing performance of the single battery. Summary of the invention

[0004] Purpose of the invention: The embodiment of the present application provides a single cell battery, aiming to overcome the current technical problem that the welding of the pole structure is not reliable, which affects the sealing performance of the single cell battery.

[0005] Technical solution: The embodiment of the present application discloses a single cell battery, including a cover plate assembly, wherein the cover plate assembly includes:

[0006] The cover plate body has an assembly hole;

[0007] A first pole, comprising a penetration portion and a first main body portion, wherein the first main body portion is disposed on one side of the cover body along the thickness direction, the penetration portion is connected to the first main body portion, and at least a portion thereof is protruded into the assembly hole;

[0008] A second pole, comprising a connecting portion and a second main body portion, wherein the second main body portion is arranged on a side of the cover body away from the first main body portion, the connecting portion is connected to the first main body portion, and at least part of the connecting portion is protruded in the assembly hole and abuts against the first main body portion, the connecting portion is provided with a through hole along the thickness direction, and the through-hole portion is penetrated in the through hole;

[0009] The penetration portion and the connection portion are welded to form a first welding portion;

[0010] The first main body portion and the connecting portion are welded to form a second welding portion.

[0011] In some embodiments, along the horizontal direction of the cover plate assembly, the penetration portion has a minimum dimension d from the hole wall of the through hole, satisfying 0.05 mm ≤ d ≤ 0.2 mm.

[0012] In some embodiments, a recessed groove is formed on a side of the second pole away from the first main body, and the recessed groove is communicated with the through hole.

[0013] In some embodiments, the connecting portion includes a connected bottom wall and side wall, the bottom wall abuts against the first main body portion, the side wall is connected to the side of the bottom wall facing away from the first main body portion, the bottom wall and the side wall form the groove, and the second main body portion is connected to the side of the side wall facing away from the groove.

[0014] In some embodiments, the connecting portion has a thickness dimension h, the first welding portion has a penetration dimension h1, and the second welding portion has a penetration dimension h2, satisfying: 0.5mm≤h≤1.5mm, 0.8≤h1 / h≤1.5, 0.5≤(h2-h) / h≤1.

[0015] In some embodiments, the first weld portion has a weld width dimension w1 satisfying 0.3 mm≤w1≤2 mm, and the second weld portion has a weld width dimension w2 satisfying 1.5 mm≤w2≤5 mm.

[0016] In some embodiments, along the horizontal direction of the cover plate assembly, the sink has a minimum dimension c that satisfies 3.5 mm ≤ c ≤ 20 mm.

[0017] In some embodiments, the penetration portion is provided with a rivet hole at an end away from the first main body portion, the diameter of the rivet hole is R, the hole depth is H, and the following conditions are satisfied: 1.5mm≤R≤5mm, 0.1mm≤H≤1mm.

[0018] In some embodiments, the cross-section of the penetration portion and the through hole along the horizontal direction of the cover plate assembly is any one of a circular, elliptical or polygonal shape.

[0019] In some embodiments, the cover assembly further includes a first seal and a second seal, the first seal includes a first section and a second section connected to each other, the first section is sandwiched between the first main body and the cover body, and the second section is sandwiched between the first main body and the second main body;

[0020] The second sealing member is sandwiched between the cover body and the second main body portion and is located at a side of the second section away from the connecting portion.

[0021] The present application also discloses a process for preparing a single cell battery, comprising the following steps:

[0022] Assembling the cover assembly;

[0023] The contact surface between the penetration part and the connection part is welded by seam welding;

[0024] The bottom wall of the connecting part and the first main body part are welded in the sink by penetration welding.

[0025] In some embodiments, the assembly cover assembly includes:

[0026] The penetration portion and the connection portion are positioned and riveted, and after the riveting is completed, seam welding and penetration welding are performed.

[0027] The present application also discloses a battery pack, comprising the single battery as described in the above embodiment.

[0028] Beneficial effects: The single cell battery in the embodiment of the present application includes a cover assembly, which includes a cover body, a first pole and a second pole; the cover body has an assembly hole; the first pole includes a penetration portion and a first main body portion, the first main body portion is arranged on one side of the cover body along the thickness direction, the penetration portion is connected to the first main body portion, and at least part of it is protruded into the assembly hole; the second pole includes a connecting portion and a second main body portion, the second main body portion is arranged on the side of the cover body away from the first main body portion, the connecting portion is connected to the first main body portion, and at least part of it is protruded into the assembly hole and abuts against the first main body portion, the connecting portion is provided with a through hole along the thickness direction, and the penetration portion is penetrated in the through hole; the penetration portion and the connecting portion are welded to form a first welding portion; the first main body portion and the connecting portion are welded to form a second welding portion. The double welding structure increases the stability of the connection between the first pole and the second pole, ensures stable battery performance, and prevents the first pole and the second pole from becoming relatively loose during transportation or operation of the battery; at the same time, it effectively avoids the risk of electrolyte leakage from the pole connection, improves the sealing of the single cell, extends the battery life, and also reduces the safety hazards caused by electrolyte leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is a schematic diagram of the three-dimensional structure of a cover plate assembly in a single cell according to an embodiment of the present application;

[0031] Figure 2 This is a schematic diagram of the top view of the cover plate assembly in the single cell of the embodiment of the present application;

[0032] Figure 3 for Figure 2 A schematic cross-sectional view along the AA direction, showing a first welding portion and a second welding portion;

[0033] Figure 4 for Figure 2 A cross-sectional schematic diagram along the AA direction is a schematic diagram of the structure after the first pole and the second pole are assembled and before welding;

[0034] Figure 5 for Figure 4 A partial enlarged schematic diagram of point B in the middle;

[0035] Figure 6 This is a schematic diagram of the exploded structure of the cover plate assembly in the single cell of the embodiment of the present application;

[0036] Figure numerals: 1, cover assembly; 11, cover body; 110, assembly hole; 12, first pole; 121, penetration portion; 122, first main body; X, thickness direction; 13, second pole; 131, connection portion; 132, second main body; 1310, through hole; 14, first welding portion; 15, second welding portion; Y, horizontal direction; 130, sinking groove; 1311, bottom wall; 1312, side wall; 1210, rivet hole; 16, first sealing member; 17, second sealing member; 161, first section; 162, second section; 18, lower plastic; 19, upper plastic. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0038] In the description of the present application, it should be understood that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In the description of the present application, "multiple" means two or more, and at least one means one, two or more, unless otherwise clearly and specifically limited. The terms "first", "second", "third", etc. are only used to name the parts or embodiments with numbers for the convenience of description, and do not imply that there is an order of importance between the parts or embodiments.

[0039] It should also be noted that in the drawings of the present application specification, the arrow marked with X indicates the thickness direction, and the arrow marked with Y indicates the horizontal direction. In the description of the present application, the thickness direction and the horizontal direction are introduced to more clearly define the structure and relative position relationship of each component in the single cell. In actual implementation, the thickness direction and the horizontal direction are perpendicular to each other to optimize the layout of the single cell. In the description of the present application, "vertical" means completely perpendicular to 90° or almost completely perpendicular, for example, within the range of 80° to 100°, it is considered vertical. Similarly, "parallel" means completely parallel or almost completely parallel, for example, within the range of 10° of completely parallel, it is considered parallel.

[0040] As the preamble of the embodiment of the present application, the lithium battery is composed of a shell, a battery cell arranged in the shell, and a cover plate. The lithium battery cover plate structure is a very important part of it. The cover plate structure is provided with a pole, which is used to electrically connect the battery cell and connect to the external circuit. The lithium battery cover plate is provided with a pole structure, including an upper pole and a lower pole, which are welded and fixed to the upper pole and the lower pole to achieve the joint clamping of the cover plate body, the sealing ring and the insulating member to ensure that the sealing performance, insulation performance, durability and other series of performances meet the corresponding standards during the later use. However, the traditional welding method has insufficient structural strength, which affects the sealing performance of the single battery.

[0041] In view of this, an embodiment of the present application provides a single cell battery, aiming to solve at least one of the above-mentioned technical problems.

[0042] See also Figures 1 to 6As shown, the single cell disclosed in the embodiment of the present application includes a cover plate assembly, which plays a key role in protecting the internal structure of the shell and realizing external connection in the single cell. On the one hand, the cover plate body in the cover plate assembly can seal the electrode assembly and electrolyte inside the battery in a relatively stable environment, preventing external impurities from entering the battery and avoiding interference with the chemical reaction inside the battery; on the other hand, the pole on the cover plate assembly is the interface for connecting the battery with the external circuit, so that the battery can be charged and discharged. The cover plate assembly includes a cover plate body, a first pole and a second pole; the cover plate body has an assembly hole; the first pole includes a penetration portion and a first main body portion, the first main body portion is arranged on one side of the cover plate body along the thickness direction, the penetration portion is connected to the first main body portion, and at least part of it is protruded in the assembly hole; the second pole includes a connecting portion and a second main body portion, the second main body portion is arranged on the side of the cover plate body away from the first main body portion, the connecting portion is connected to the first main body portion, and at least part of it is protruded in the assembly hole and abuts against the first main body portion. By using the assembly hole of the cover plate body, the penetration portion and the connecting portion are at least partly protruded therein and abut against each other, providing accurate positioning for pole assembly and improving assembly efficiency. The connecting portion is provided with a through hole along the thickness direction, and the penetration portion is penetrated in the through hole; the penetration portion and the connecting portion are welded to form a first welding portion; the first main body portion and the connecting portion are welded to form a second welding portion.

[0043] It should be understood that the penetration portion passes through the through hole of the connection portion and is welded to the connection portion to form a first welding portion, and the first main body portion is welded to the connection portion to form a second welding portion. The double welding method is adopted, which greatly enhances the connection strength between the two poles, so that the first pole and the second pole are firmly connected and the current conduction is stable under various complex working conditions such as charging and discharging of the single battery, avoiding problems such as increased internal resistance and heat generation of the battery due to loose connection, and ensuring the overall performance of the single battery. At the same time, the double welding connection method is adopted between the first pole and the second pole, which effectively prevents the electrolyte from seeping out from the pole connection, avoids the battery drying up and performance degradation due to the loss of electrolyte, and prevents the electrolyte from corroding other parts of the battery, reduces safety hazards, strengthens the sealing of the battery, and extends the battery life.

[0044] See also Figure 4 and Figure 5As shown, in some embodiments, along the horizontal direction of the cover plate assembly, the minimum dimension d between the penetration portion and the hole wall of the through hole satisfies 0.05mm≤d≤0.2mm. It should be understood that by limiting the minimum dimension d between the penetration portion and the hole wall of the through hole to meet the above range, it is ensured that the gap formed between the two provides space for the welding of the penetration portion and the connecting portion, so that the solder can be fully filled and evenly distributed in the gap, avoiding insufficient solder filling due to a large gap, resulting in defects such as cold welding and leaking welding, avoiding the difficulty of solder entering due to a small gap, ensuring the welding quality of the first welding portion, and improving the reliability of the pole connection. At the same time, the appropriate spacing d can ensure the stability of electrical conduction between the penetration portion and the connecting portion, reduce the problems of resistance change and electric field distortion caused by unreasonable spacing, ensure smooth current transmission during the charging and discharging process of the single cell, and ensure the stability of the electrical performance of the single cell. Furthermore, the appropriate spacing d allows the penetration part to form a tighter fit when penetrating the through hole, avoiding relative shaking due to excessive gap, affecting welding quality and welding efficiency, and destroying the welding structure. It also avoids assembly difficulties or damage to the pole due to too small a gap, which helps to enhance the stability of the pole connection structure and ensure the reliability of the single cell in complex use environments.

[0045] See also Figures 3 to 5 As shown, in some embodiments, the second pole is provided with a sink groove on the side away from the first main body, and the sink groove is connected to the through hole. It should be understood that by providing a sink groove, an operating space is provided for the welding operation, so that the welding tools or solder can more conveniently reach the welding area, reduce the difficulty of welding, make the welding operation easier to perform, help improve the welding quality, and ensure the welding reliability of the first main body and the connecting part. At the same time, the sink groove can collect and accommodate excess solder, prevent the solder from flowing to other unnecessary parts at will, avoid contamination of other parts of the battery or affect the overall performance of the battery, and improve the battery production yield. Furthermore, the surface area of ​​the second pole on one side of the sink groove is increased, the heat dissipation area is increased, the internal temperature of the battery is effectively reduced, the adverse effects on the battery performance and life due to excessive temperature are avoided, and the thermal stability and safety of the battery are improved.

[0046] See also Figure 4 As shown, in some embodiments, the connection portion includes a bottom wall and a side wall connected to each other, the bottom wall abuts against the first main body, the side wall surrounds and is connected to the side of the bottom wall away from the first main body, the bottom wall and the side wall form a sink, and the second main body surrounds and is connected to the side of the side wall away from the sink. It should be understood that the bottom wall abuts against the first main body to form a stable support, and the side wall surrounds the bottom wall to enhance the overall structural strength of the connection portion, prevent deformation during welding or use, ensure that the first pole and the second pole are firmly connected and not easy to loosen, and ensure stable battery performance. At the same time, the second main body surrounds and is connected to the side of the side wall away from the sink, with a compact and reasonable layout, which improves the internal space utilization of the battery.

[0047] See also Figure 3 As shown, in some embodiments, the connection portion has a thickness dimension h, the first welding portion has a penetration dimension h1, and the second welding portion has a penetration dimension h2, satisfying: 0.5mm≤h≤1.5mm, 0.8≤h1 / h≤1.5, 0.5≤(h2-h) / h≤1. It should be understood that by limiting the thickness dimension of the connection portion to be within the range of 0.5mm to 1.5mm, it is ensured that the connection portion has sufficient structural strength, so that it can remain stable when subjected to internal pressure, external impact and vibration of the battery, avoid deformation or damage due to too thin thickness, ensure the reliability of the connection between the poles, and thus ensure the normal operation of the battery. By limiting the ratio of the penetration dimension of the first welding portion to the thickness dimension of the connection portion to be between 0.8 and 1.5, it is ensured that the first welding portion has sufficient penetration, ensures that a firm welding connection is formed between the penetration portion and the connection portion, avoids insufficient welding strength due to insufficient penetration, enables the first welding portion to effectively withstand mechanical stress and electrical load, and ensures the stability of current transmission. By limiting the ratio of the portion of the second weld depth that exceeds the thickness of the connection part to the thickness of the connection part to between 0.5 and 1, it is ensured that the second weld part will neither damage the connection part structure due to excessive penetration nor fail to provide sufficient connection strength due to too small a penetration. This helps to improve the connection reliability between the first main body and the connection part, avoid negative impacts on the connection part due to excessive welding depth, and ensure long-term stable operation of the battery.

[0048] Specifically, the thickness dimension h of the connection portion can be any value among 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, or a range value between two values. Within the above range, if the thickness dimension h of the connection portion is larger, the structural strength of the connection portion is higher and the space occupied is larger; conversely, if the thickness dimension h of the connection portion is smaller, the structural strength of the connection portion is smaller and the space occupied is smaller. h1 / h can be any value among 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or a range value between two values. Within the above range, if the ratio of the penetration dimension of the first welding portion to the thickness dimension of the connection portion is larger, the penetration is larger, the welding strength is larger, and the current transmission stability is higher. If the ratio of the penetration dimension of the first welding portion to the thickness dimension of the connection portion is greater than 1.5, the penetration is too large, which is easy to cause the risk of welding through, affecting the structure of the first pole and the current transmission stability. If the ratio of the penetration dimension of the first welding part to the thickness dimension of the connecting part is less than 0.8, the penetration is too small, and the connection strength between the first main body and the connecting part is weakened. (h2-h) / h can be any value among 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 or a range value between two values. Within the above range, if the ratio of the penetration dimension of the second welding part exceeding the thickness dimension of the connecting part to the thickness dimension of the connecting part is larger, the penetration of the second welding part is larger, and the connection reliability of the second welding part is higher. If (h2-h) / h is less than 0.5, the penetration of the second welding part is too small, the connection strength is low, and the reliability is poor. If (h2-h) / h is greater than 1.0, the penetration of the second welding part is too large, which is easy to cause the risk of welding through, affecting the structure of the first pole and the stability of current transmission.

[0049] See also Figure 3As shown, in some embodiments, the first welding portion has a weld width dimension w1, which satisfies 0.3mm≤w1≤2mm, and the second welding portion has a weld width dimension w2, which satisfies 1.5mm≤w2≤5mm. It should be understood that by limiting the range of the weld width dimension w1 of the first welding portion to between 0.3mm and 2mm, it is ensured that there is sufficient welding width between the penetration portion and the connection portion. The larger the weld width, the larger the area of ​​the welding area, and the higher the strength of the connection. When w1 is within the above range, the first welding portion can withstand the mechanical stress that may be generated by the battery during normal use, such as thermal expansion and contraction caused by temperature changes, internal forces generated during the charge and discharge cycle of the battery, and possible external impacts, etc., to avoid cracking or loosening of the weld due to too small a weld width, thereby ensuring a reliable connection between the first pole and the second pole and a stable transmission of current. By limiting the weld width dimension w2 of the second welding portion to between 1.5mm and 5mm, a larger weld width provides a stronger guarantee for the connection between the first main body and the connection portion. Within the above range, the second welding part can better withstand various forces from inside and outside the battery, ensure that the first main body and the connecting part are tightly combined, and prevent the pole structure from being separated due to insufficient welding strength under long-term use or in harsh environments, thereby improving the stability and safety of the battery.

[0050] Specifically, w1 can be any value among 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, or a range between two values. w2 can be any value among 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, or a range between two values. By limiting the fusion width of the first welding portion and the second welding portion, the resistance caused by poor welding can be reduced, local overheating caused by excessive local resistance can be prevented, and the battery performance degradation and possible safety hazards caused by overheating can be avoided. At the same time, ensuring that the first pole and the second pole are firmly welded can help reduce the contact resistance at the connection of the pole structure, improve the charging and discharging efficiency of the battery, and extend the service life of the battery.

[0051] Next, multiple embodiments are provided to illustrate the effect of the secondary battery of the present application. After the welded pole is cut, polished and other corresponding processes are performed, h, h1 and h2 are obtained through metallographic observation. In order to further reduce the experimental error, h, h1 and h2 are obtained by testing multiple poles and taking the average value.

[0052] Among them, by testing the internal resistance after welding, the pole internal resistance is required to be lower than 0.035mΩ, so as to judge the current capacity and sealing between the first pole and the second pole; by applying thrust along the thickness direction on the welding surface, the pole strength can withstand a maximum thrust greater than or equal to 2000N, so as to judge the connection strength between the first pole and the second pole. If the first pole and the second pole are only welded by seam welding or penetration welding, the maximum thrust that the pole strength can withstand is about 1500N, which cannot meet the pole strength requirements and sealing.

[0053] The test results of the embodiments are shown in the following table:

[0054]

[0055] As shown in the table above, in Examples 1 to 12, when h is between 0.5 mm and 1.5 mm, h1 / h is between 0.8 and 1.5, and (h2-h) / h is between 0.5 and 1, the ultimate thrust that can be sustained along the thickness direction after the first pole and the second pole are connected is greater than 2000 N, the internal resistance of the pole structure is lower than 0.035 mΩ, the connection strength of the pole structure is large, and the overcurrent capacity is met, and the sealing performance of the single cell is good. In Examples 13 and 14, when (h2-h) / h is greater than 1, the ultimate thrust that can be sustained along the thickness direction after the first pole and the second pole are connected increases, the internal resistance of the pole structure increases, the connection strength of the pole structure increases, but the overcurrent capacity decreases. In Examples 15 and 16, when (h2-h) / h is less than 0.5, the ultimate thrust that can be withstood along the thickness direction after the first pole is connected to the second pole is reduced, and the internal resistance value is lower than 0.035mΩ, which meets the overcurrent capacity, but the connection strength of the pole structure is reduced. In Examples 17 and 18, when h1 / h is less than 0.8, the ultimate thrust that can be withstood along the thickness direction after the first pole is connected to the second pole is reduced, and the internal resistance value is lower than 0.035mΩ, which meets the overcurrent capacity, but the connection strength of the pole structure is reduced. In Examples 19 and 20, when h1 / h is greater than 1.5, the ultimate thrust that can be withstood along the thickness direction after the first pole is connected to the second pole is increased, the internal resistance value of the pole structure is increased, and the connection strength of the pole structure is improved, but the overcurrent capacity is reduced.

[0056] See also Figure 5As shown, in some embodiments, along the horizontal direction of the cover plate assembly, the sink has a minimum size c, satisfying 3.5mm≤c≤20mm. It should be understood that by limiting the minimum size c of the sink in the horizontal direction to be within the range of 3.5mm to 20mm, a suitable space is provided for the welding operation. To ensure that the welding tool or solder enters the sink smoothly, the first main body and the connection part are welded, and the welding quality of the second welding part is ensured. At the same time, the sink is prevented from being too large to weaken the structural strength of the connection part, and too much solder is prevented from flowing in, so as to ensure the stability and controllability of the welding process. A larger sink size can increase the heat dissipation area of ​​the second pole, which is conducive to the heat dissipation of the battery when it is working, and avoids local overheating affecting the battery performance. At the same time, the reasonable size takes into account the stability of the connection structure, and while ensuring the heat dissipation function, the second pole can withstand the internal pressure of the battery and the external vibration impact, ensuring the reliability of the battery structure. Furthermore, the size of the sink is convenient for mold manufacturing and product assembly, reducing the manufacturing difficulty and cost.

[0057] See also Figure 4 As shown, in some embodiments, the penetration portion is provided with a rivet hole at one end away from the first main body portion, and the aperture of the rivet hole is R, and the hole depth is H, satisfying: 1.5mm≤R≤5mm, 0.1mm≤H≤1mm. It should be understood that by setting the aperture R and the hole depth H of the rivet block to meet the above range, the penetration portion is riveted into the through hole, and effective riveting is achieved without excessively weakening the structural strength of the penetration portion, and the connection reliability between the penetration portion and the connecting portion is further enhanced. The penetration portion is fixed in the through hole in the form of pre-riveting to ensure the alignment of the first pole and the second pole, and to ensure the connection reliability and stability between the first pole and the second pole. Specifically, the aperture R can be any value of 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, or a range value between two values. The hole depth H can be any value among 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, or a range between two values. If the hole diameter R is larger and the hole depth H is larger, the deformation of the area of ​​the penetration portion close to the riveting hole is larger, and the fixing force between the penetration portion and the hole wall of the through hole is larger.

[0058] See also Figure 6As shown, in some embodiments, the cross-section of the penetration portion and the through hole along the horizontal direction of the cover plate assembly is any one of a circle, an ellipse or a polygon. It should be understood that if the cross-section of the penetration portion and the through hole is circular, the quick plug-in and fit of the first pole and the second pole can be achieved, and the assembly efficiency is improved. At the same time, the circular structure can better disperse the stress, reduce the risk of cracking at the weld or damage to the pole caused by stress concentration, and ensure the stability and reliability of the battery. If the cross-section of the penetration portion and the through hole is elliptical, the relative rotation of the first pole and the second pole can be effectively prevented to ensure the stability of the cover plate assembly structure. If the cross-section of the penetration portion and the through hole is polygonal, the polygon can be square or rhombus, or other shapes, which will not be repeated here. The polygonal structure can effectively disperse stress. When the battery is subjected to vibration or impact at a specific angle, the polygonal structure can direct the stress to a specific direction, reduce the direct impact on the welding part, and improve the impact resistance of the battery.

[0059] See also Figures 3 to 6 As shown, in some embodiments, the cover assembly further includes a first seal and a second seal, the first seal includes a first section and a second section connected, the first section is sandwiched between the first main body and the cover body, and the second section is sandwiched between the first main body and the second main body; the second seal is sandwiched between the cover body and the second main body, and is located on the side of the second section away from the connecting portion. It should be understood that by arranging the first seal and the second seal to achieve a double sealing structure, the electrolyte leakage is effectively blocked, and impurities such as external air and moisture are prevented from entering the battery, which greatly improves the sealing and protection performance of the battery and prolongs the battery life. At the same time, the two seals not only play a sealing role, but also can disperse stress between the pole and the cover body. When the battery is working, it will produce thermal expansion and contraction due to charging and discharging. When it is subjected to external forces such as vibration and impact, the seal can buffer these stresses, avoid stress concentration at the connection between the pole and the cover body, prevent the pole from loosening or the cover from breaking due to excessive stress, and enhance the structural stability of the entire cover assembly. The layout design of the first seal and the second seal rationally utilizes the internal space of the cover assembly, reduces space utilization, helps maintain the compactness of the internal structure of the battery, facilitates the layout of other components inside the battery, and is conducive to the miniaturization and lightweight design of the battery.

[0060] The present application also discloses a preparation process of a single cell. The single cell based on the above embodiment includes the following steps: assembling a cover plate assembly; welding the contact surface of the penetration part and the connection part by seam welding; welding the bottom wall of the connection part and the first main body in the sink by penetration welding. It should be understood that seam welding is used to initially construct a connection structure between the first pole and the second pole, and to form a preliminary positioning, and at the same time, a first seal is constructed to prevent the connection part and the first main body from being relatively displaced when subjected to welding stress, strengthen the fixed relationship between the first pole and the second pole, enhance the ability of the single cell to resist external forces such as vibration and impact during use, effectively prevent the pole from loosening, and ensure the stability of battery performance. Afterwards, penetration welding is used to seal the second component to improve the overall sealing of the single cell; the structural stability after seam welding helps to improve the quality of penetration welding, and the penetration part and the connection part are closely fitted by seam welding. When performing penetration welding, heat can be more evenly distributed between the bottom wall of the connection part and the first main body. This uniform heat distribution is conducive to forming a better quality weld and reducing welding defects such as pores and cracks. At the same time, seam welding first can clean up some impurities on the contact surface, making the welding area purer during penetration welding, further improving the welding quality, ensuring good electrical connection between the poles, reducing contact resistance, and improving the battery's charging and discharging efficiency.

[0061] In some embodiments, assembling the cover plate assembly includes: positioning and riveting the penetration portion and the connecting portion, and after the riveting is completed, performing seam welding and penetration welding. It should be understood that by positioning and riveting the penetration portion and the connecting portion before seam welding, it is ensured that the positions of the two before welding are accurate, and the stable structure after positioning and riveting is conducive to the smooth seam welding, avoiding the misalignment of the penetration portion and the connecting portion during the welding process. Accurate positioning can ensure that the welds are evenly distributed along the preset contact surface, thereby improving the welding quality. Positioning riveting provides a clear benchmark for subsequent welding. When performing seam welding and penetration welding, workers do not need to repeatedly adjust the position of components, which reduces the operation steps, improves work efficiency, and reduces product defective rates.

[0062] The present application also discloses a battery pack, comprising the single cell as described in the above embodiment, and thus, it can have all the technical features and technical effects of the above single cell, which will not be described in detail here.

[0063] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0064] The above is a detailed introduction to a single cell, a battery pack and a preparation process thereof provided in the embodiments of the present application, and specific examples are used to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application; ordinary technicians in this field should understand that: they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with 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.

Claims

1. A single cell battery, characterized in that: A cover plate assembly is included, wherein the cover plate assembly includes: The cover plate body has an assembly hole; A first pole, comprising a penetration portion and a first main body portion, wherein the first main body portion is disposed on one side of the cover body along the thickness direction, the penetration portion is connected to the first main body portion, and at least a portion thereof is protruded into the assembly hole; A second pole, comprising a connecting portion and a second main body portion, wherein the second main body portion is arranged on a side of the cover body away from the first main body portion, the connecting portion is connected to the first main body portion, and at least part of the connecting portion is protruded in the assembly hole and abuts against the first main body portion, the connecting portion is provided with a through hole along the thickness direction, and the through-hole portion is penetrated in the through hole; The penetration portion and the connection portion are welded to form a first welding portion; The first main body portion and the connecting portion are welded to form a second welding portion.

2. The single cell according to claim 1, characterized in that: Along the horizontal direction of the cover plate assembly, the penetration portion has a minimum dimension d from the hole wall of the through hole, satisfying 0.05 mm ≤ d ≤ 0.2 mm.

3. The single cell according to claim 1, characterized in that: The second pole is provided with a sink groove on a side away from the first main body, and the sink groove is communicated with the through hole.

4. The single cell according to claim 3, characterized in that: The connecting portion includes a connected bottom wall and side walls, the bottom wall is abutted against the first main body portion, the side wall is connected around the side of the bottom wall away from the first main body portion, the bottom wall and the side wall form the sinking groove, and the second main body portion is connected around the side of the side wall away from the sinking groove.

5. The single cell according to claim 3, characterized in that: The connecting portion has a thickness dimension h, the first welding portion has a penetration dimension h1, and the second welding portion has a penetration dimension h2, satisfying the following: 0.5 mm ≤ h ≤ 1.5 mm, 0.8 ≤ h1 / h ≤ 1.5, and 0.5 ≤ (h2-h) / h ≤ 1.

6. The single cell according to claim 5, characterized in that: The first weld portion has a weld width dimension w1 satisfying 0.3 mm ≤ w1 ≤ 2 mm, and the second weld portion has a weld width dimension w2 satisfying 1.5 mm ≤ w2 ≤ 5 mm.

7. The single cell according to claim 3, characterized in that: Along the horizontal direction of the cover plate assembly, the sink has a minimum dimension c, satisfying 3.5 mm ≤ c ≤ 20 mm.

8. The single cell according to claim 1, characterized in that: The penetration portion is provided with a rivet hole at one end away from the first main body portion, the diameter of the rivet hole is R, the depth of the hole is H, and the following conditions are satisfied: 1.5mm≤R≤5mm, 0.1mm≤H≤1mm.

9. The single cell according to claim 1, characterized in that: The cross-section of the penetration portion and the through hole along the horizontal direction of the cover plate assembly is any one of a circular, an elliptical or a polygonal shape.

10. The single cell according to claim 1, characterized in that: The cover plate assembly further includes a first seal and a second seal, the first seal includes a first section and a second section connected to each other, the first section is sandwiched between the first main body and the cover plate body, and the second section is sandwiched between the first main body and the second main body; The second sealing member is sandwiched between the cover body and the second main body portion and is located at a side of the second section away from the connecting portion.

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