A single cell

Abstract

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

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a single-cell battery. Background Technology

[0002] A lithium battery consists of a casing, battery cells housed within the casing, and a cover plate. The cover plate structure is a crucial component, featuring terminals for electrical connection to the battery cells and for connection to external circuitry.

[0003] The lithium battery cover has an electrode structure, including an upper electrode and a lower electrode. These electrodes are welded together to secure the cover body, sealing ring, and insulation components, ensuring that the battery's sealing performance, insulation performance, durability, and other properties meet relevant standards during use. However, traditional welding methods lack structural strength, affecting the sealing performance of individual cells. Summary of the Invention

[0004] Purpose of the invention: The embodiments of this application provide a single-cell battery that aims to overcome the technical problem of unreliable welding of the current electrode structure, which affects the sealing performance of the single-cell battery.

[0005] Technical solution: This application discloses a single-cell battery, including a cover plate assembly, the cover plate assembly comprising:

[0006] The cover plate body has assembly holes;

[0007] The first pole post includes a through portion and a first main body portion. The first main body portion is disposed on one side of the cover plate body along the thickness direction. The through portion is connected to the first main body portion and at least partially protrudes into the assembly hole.

[0008] The second pole post includes a connecting part and a second main body part. The second main body part is disposed on the side of the cover plate body away from the first main body part. The connecting part is connected to the first main body part and at least partially protrudes into the assembly hole and abuts against the first main body part. The connecting part has a through hole along the thickness direction, and the through part passes through the through hole.

[0009] The through portion is welded to the connecting portion to form a first weld portion;

[0010] The first main body is welded to the connecting part to form a second welded part.

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

[0012] In some embodiments, the second pole post has a groove on the side opposite to the first main body, and the groove is connected to the through hole.

[0013] In some embodiments, the connecting portion includes a connected bottom wall and a side wall, the bottom wall abutting against the first main body portion, the side wall being connected around the bottom wall on the side away from the first main body portion, the bottom wall and the side wall forming the sinkhole, and the second main body portion being connected around the side wall on the side away from the sinkhole.

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

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

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

[0017] In some embodiments, the through portion has a rivet hole at one end opposite to the first main body portion. The diameter of the rivet hole is R and the depth is H, satisfying: 1.5mm≤R≤5mm, 0.1mm≤H≤1mm.

[0018] In some embodiments, the cross-section of the through 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.

[0019] In some embodiments, the cover plate assembly further includes a first seal and a second seal, the first seal including a first segment and a second segment connected together, the first segment being sandwiched between the first main body portion and the cover plate body, and the second segment being sandwiched between the first main body portion and the second main body portion;

[0020] The second sealing element is sandwiched between the cover plate body and the second main body, and is located on the side of the second section away from the connecting part.

[0021] This application also discloses a process for fabricating a single-cell battery, comprising the following steps:

[0022] Assemble the cover plate assembly;

[0023] The contact surfaces of the through-hole part and the connecting part are welded using a seam welding method.

[0024] The bottom wall of the connection part and the first main body part are welded together in the settling tank by through welding.

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

[0026] The through part and the connecting part are positioned and riveted together. After the riveting is completed, seam welding and through welding are performed.

[0027] This application also discloses a battery pack, including the single battery cells as described in the above embodiments.

[0028] Beneficial effects: The single battery in this embodiment includes a cover plate assembly, which includes a cover plate body, a first electrode post, and a second electrode post. The cover plate body has an assembly hole. The first electrode post includes a through portion and a first main body portion. The first main body portion is disposed on one side of the cover plate body along the thickness direction. The through portion is connected to the first main body portion and at least partially protrudes into the assembly hole. The second electrode post includes a connecting portion and a second main body portion. The second main body portion is disposed on the side of the cover plate body opposite to the first main body portion. The connecting portion is connected to the first main body portion and at least partially protrudes into the assembly hole and abuts against the first main body portion. The connecting portion has a through hole along the thickness direction, and the through portion passes through the through hole. The through portion and the connecting portion are welded to form a first weld portion. The first main body portion and the connecting portion are welded to form a second weld portion. The double-welded structure increases the stability of the connection between the first and second terminals, ensuring stable battery performance and preventing relative loosening of the first and second terminals during handling or operation. At the same time, it effectively avoids the risk of electrolyte leakage from the terminal connection, improves the sealing of individual cells, extends battery life, and reduces safety hazards caused by electrolyte leakage. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

[0031] Figure 2 This is a top view of the cover plate assembly in a single battery cell according to an embodiment of this application;

[0032] Figure 3 for Figure 2 A cross-sectional view along the AA direction, showing the first welded part and the second welded part;

[0033] Figure 4 for Figure 2 A cross-sectional view along the AA direction, showing the structure of the first and second poles after assembly and before welding;

[0034] Figure 5 for Figure 4 A magnified view of a portion of point B in the middle;

[0035] Figure 6 This is an exploded structural diagram of the cover plate assembly in a single battery cell according to an embodiment of this application;

[0036] Reference numerals: 1. Cover plate assembly; 11. Cover plate body; 110. Assembly hole; 12. First pole post; 121. Through part; 122. First main body part; X, thickness direction; 13. Second pole post; 131. Connecting part; 132. Second main body part; 1310. Through hole; 14. First welding part; 15. Second welding part; Y, horizontal direction; 130. Slot; 1311. Bottom wall; 1312. Side wall; 1210. Riveting hole; 16. First seal; 17. Second seal; 161. First section; 162. Second section; 18. Lower plastic; 19. Upper plastic. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0038] In the description of this application, it should be understood that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In the description of this application, "multiple" means two or more, and "at least one" can refer to one, two, or more, unless otherwise explicitly specified. The terms "first," "second," and "third," etc., are only for the convenience of description and are used to name parts or embodiments by number, and do not imply any order of importance between the parts or embodiments.

[0039] It should also be noted that in the accompanying drawings of this application, the arrow marked X indicates the thickness direction, and the arrow marked Y indicates the horizontal direction. The introduction of the thickness and horizontal directions in this application's description is to more clearly define the structure and relative positional relationships of the components within a single cell. In actual implementation, the thickness and horizontal directions are perpendicular to each other to optimize the layout of the single cell. In this application's description, "perpendicular" means completely perpendicular to 90° or almost completely perpendicular; for example, an angle between 80° and 100° is considered perpendicular. Similarly, "parallel" means completely parallel or almost completely parallel; for example, a completely parallel angle within 10° is considered parallel.

[0040] As a preamble to the embodiments of this application, a lithium battery comprises a casing, a battery cell housed within the casing, and a cover plate. The lithium battery cover plate structure is a crucial component, featuring terminals for electrical connection to the battery cell and external circuitry. The cover plate includes an upper terminal and a lower terminal, which are welded together to secure the cover plate body, sealing ring, and insulating components. This ensures that the battery's sealing performance, insulation performance, durability, and other properties meet relevant standards during subsequent use. However, traditional welding methods suffer from insufficient structural strength, impacting the sealing performance of individual battery cells.

[0041] In view of this, embodiments of this application provide a single-cell battery, which aims to solve at least one of the above-mentioned technical problems.

[0042] Please see Figures 1 to 6As shown in the embodiments of this application, the single-cell battery includes a cover plate assembly. The cover plate assembly plays a crucial role in protecting the internal structure of the single-cell battery and enabling external connections. On one hand, the cover plate body in the cover plate assembly can seal the electrode components and electrolyte inside the battery in a relatively stable environment, preventing external impurities from entering the battery and avoiding interference with the internal chemical reactions. On the other hand, the terminals on the cover plate assembly are the interfaces connecting the battery to external circuits, enabling the battery to be charged and discharged. The cover plate assembly includes a cover plate body, a first pole post, and a second pole post. The cover plate body has an assembly hole. The first pole post includes a through portion and a first main body portion. The first main body portion is located on one side of the cover plate body along the thickness direction. The through portion is connected to the first main body portion and at least partially protrudes into the assembly hole. The second pole post includes a connecting portion and a second main body portion. The second main body portion is located on the side of the cover plate body opposite to the first main body portion. The connecting portion is connected to the first main body portion and at least partially protrudes into the assembly hole, abutting against the first main body portion. Utilizing the assembly hole of the cover plate body, both the through portion and the connecting portion at least partially protrude therein and abut against each other, providing precise positioning for pole post assembly and improving assembly efficiency. The connecting portion has a through hole along the thickness direction, and the through portion passes through the through hole. The through portion and the connecting portion are welded to form a first weld portion. The first main body portion and the connecting portion are welded to form a second weld portion.

[0043] It's important to understand that the first welded part is formed by the through-hole of the connecting part and welding it to the connecting part, while the first main body is welded to the connecting part to form the second welded part. This double welding method greatly enhances the connection strength between the two terminals, ensuring a stable connection between the first and second terminals under various complex operating conditions such as charging and discharging. This stable current conduction prevents problems such as increased internal resistance and overheating caused by loose connections, thus guaranteeing the overall performance of the individual battery. Simultaneously, the double welding connection between the first and second terminals effectively prevents electrolyte leakage from the terminal connection, avoiding battery drying and performance degradation due to electrolyte loss. It also prevents electrolyte corrosion of other battery components, reducing safety hazards, strengthening battery sealing, and extending battery life.

[0044] Please see Figure 4 and Figure 5As shown, in some embodiments, along the horizontal direction of the cover plate assembly, the distance between the through-hole and the wall of the through hole has a minimum dimension d, satisfying 0.05mm ≤ d ≤ 0.2mm. It should be understood that by limiting the minimum dimension d between the through-hole and the wall of the through hole to meet the above range, the gap formed between them provides space for welding between the through-hole and the connecting part, allowing the solder to fully fill and distribute evenly within the gap. This avoids defects such as insufficient solder filling due to an excessively large gap, resulting in incomplete soldering or missing solder, and avoids defects such as insufficient solder entry due to an excessively small gap, ensuring the welding quality of the first welding part and improving the reliability of the electrode connection. Simultaneously, a suitable spacing d ensures stable electrical conduction between the through-hole and the connecting part, reducing problems such as resistance changes and electric field distortion caused by unreasonable spacing, ensuring smooth current transmission during the charging and discharging process of the single battery cell, and guaranteeing the stable electrical performance of the single battery cell. Furthermore, a suitable spacing d ensures a tighter fit when the through-hole is inserted into the through-hole, preventing relative wobbling caused by excessive gaps, which could affect welding quality and efficiency, damage the welding structure, or cause assembly difficulties or damage to the electrode post due to insufficient gaps. This helps to enhance the stability of the electrode post connection structure and ensure the reliability of the single cell in complex operating environments.

[0045] Please see Figures 3 to 5 As shown, in some embodiments, the second electrode post has a groove on the side opposite to the first main body, and the groove is connected to the through hole. It should be understood that by creating the groove, operating space is provided for welding operations, making it easier for welding tools or solder to reach the welding area, reducing welding difficulty, making welding operations easier, and helping to improve welding quality, ensuring the welding reliability between the first main body and the connecting part. At the same time, the groove can collect and contain excess solder, preventing solder from flowing randomly to other unwanted parts, avoiding contamination of other battery components or affecting the overall performance of the battery, and improving the battery production yield. Furthermore, the increased surface area of ​​the second electrode post on the side of the groove increases the heat dissipation area, effectively reducing the internal temperature of the battery, avoiding adverse effects on battery performance and lifespan due to excessive temperature, and improving the thermal stability and safety of the battery.

[0046] Please see Figure 4 As shown, in some embodiments, the connecting portion includes a connected bottom wall and a side wall. The bottom wall abuts against the first main body portion, and the side wall surrounds the bottom wall on the side opposite to the first main body portion. The bottom wall and side wall form a recessed groove, and the second main body portion surrounds the side wall on the side opposite to the recessed groove. It should be understood that the bottom wall abutting against the first main body portion forms a stable support, and the side wall surrounding the bottom wall enhances the overall structural strength of the connecting portion, preventing deformation during welding or use, ensuring a stable connection between the first and second terminals, preventing loosening, and guaranteeing stable battery performance. Simultaneously, the second main body portion surrounding the side wall on the side opposite to the recessed groove results in a compact and reasonable layout, improving the utilization rate of the battery's internal space.

[0047] Please see Figure 3 As shown, in some embodiments, the connecting portion has a thickness dimension h, the first welding portion has a penetration depth dimension h1, and the second welding portion has a penetration depth dimension h2, satisfying: 0.5mm≤h≤1.5mm, 0.8≤h1 / h≤1.5, and 0.5≤(h2-h) / h≤1. It should be understood that by limiting the thickness dimension of the connecting portion to the range of 0.5mm to 1.5mm, sufficient structural strength is ensured, enabling it to remain stable under internal battery pressure, external impact, and vibration, preventing deformation or damage due to excessive thickness, ensuring the reliability of the connection between the terminals, and thus guaranteeing normal battery operation. By limiting the ratio of the penetration depth dimension of the first welding portion to the thickness dimension of the connecting portion to between 0.8 and 1.5, sufficient penetration depth is ensured, ensuring a strong welded connection between the through-hole portion and the connecting portion, avoiding insufficient weld strength due to insufficient penetration depth, enabling the first welding portion to effectively withstand mechanical stress and electrical load, and ensuring the stability of current transmission. By limiting the ratio of the portion of the second weld depth that exceeds the thickness of the connecting portion to the thickness of the connecting portion to between 0.5 and 1, it is ensured that the second weld depth will not damage the connecting portion structure due to excessive weld depth, nor will it fail to provide sufficient connection strength due to insufficient weld depth. This helps to improve the connection reliability between the first main body and the connecting portion, avoids negative impacts on the connecting portion due to excessive weld depth, and ensures long-term stable operation of the battery.

[0048] Specifically, the thickness h of the connection can be any value or a range between two values ​​from 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, and 1.5mm. Within this range, a larger thickness h results in higher structural strength but a larger space requirement; conversely, a smaller thickness h results in lower structural strength but a smaller space requirement. h1 / h can be any value or a range between two values ​​from 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, and 1.5. Within this range, a larger ratio of the weld penetration depth to the connection thickness results in greater penetration, higher weld strength, and higher current transmission stability. If the ratio is greater than 1.5, the penetration depth is too large, increasing the risk of burn-through and affecting the structure and current transmission stability of the first electrode. If the ratio of the penetration depth of the first weld to the thickness of the connecting part is less than 0.8, the penetration depth is too small, weakening the connection strength between the first main body and the connecting part. (h²-h) / h can be any value from 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or a range between two values. Within this range, the larger the ratio of the portion of the second weld penetration depth exceeding the thickness of the connecting part to the thickness of the connecting part, the greater the penetration depth of the second weld and the higher the connection reliability. If (h²-h) / h is less than 0.5, the penetration depth of the second weld is too small, resulting in low connection strength and poor reliability. If (h²-h) / h is greater than 1.0, the penetration depth of the second weld is too large, easily causing burn-through and affecting the structure and current transmission stability of the first electrode.

[0049] Please see Figure 3As shown, in some embodiments, the first weld portion has a weld width w1, satisfying 0.3mm ≤ w1 ≤ 2mm, and the second weld portion has a weld width w2, satisfying 1.5mm ≤ w2 ≤ 5mm. It should be understood that by limiting the weld width w1 of the first weld portion to between 0.3mm and 2mm, sufficient weld width is ensured between the through-hole portion and the connecting portion. The larger the weld width, the larger the weld area, and the higher the connection strength. When w1 is within the above range, the first weld portion can withstand the mechanical stress that may occur during normal battery use, such as thermal expansion and contraction due to temperature changes, internal forces generated during battery charge and discharge cycles, and possible external impacts, avoiding cracking or loosening of the weld due to excessively small weld width, thereby ensuring a reliable connection and stable current transmission between the first and second terminals. By limiting the weld width w2 of the second weld portion to between 1.5mm and 5mm, the larger weld width provides stronger protection for the connection between the first main body and the connecting portion. Within the aforementioned range, the second welded part can better withstand various forces from inside and outside the battery, ensuring a tight connection between the first main body and the connecting part. In long-term use or harsh environments, it can prevent the separation of the pole structure due to insufficient welding strength, thereby improving the stability and safety of the battery.

[0050] Specifically, w1 can be any value or a range between two values ​​from 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, and 2.0mm. w2 can be any value or a range between two values ​​from 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, and 5.0mm. By limiting the weld width between the first and second weld portions, resistance caused by poor welding is reduced, preventing localized overheating due to excessive local resistance, and avoiding battery performance degradation and potential safety hazards caused by overheating. Simultaneously, ensuring a firm weld between the first and second terminals helps reduce contact resistance at the terminal structure connection, improves battery charging and discharging efficiency, and extends battery life.

[0051] Next, several embodiments are provided to illustrate the effect of the secondary battery of this application. After cutting and polishing the welded electrode posts, h, h1, and h2 are obtained by metallographic observation. To further reduce experimental errors, h, h1, and h2 are obtained by testing multiple electrode posts and taking the average value.

[0052] The process involves testing the internal resistance after welding, requiring the pole's internal resistance to be below 0.035 mΩ to assess the current-carrying capacity and sealing performance between the first and second poles. Applying a thrust along the thickness direction at the weld surface, the pole's strength must withstand a maximum thrust of 2000 N to determine the connection strength between the first and second poles. If only one type of weld—seam welding or through welding—is used for the first and second poles, the maximum thrust the pole can withstand is approximately 1500 N, which fails to meet the pole strength and sealing requirements.

[0053] The test results of the examples are shown in the table below:

[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 the first and second terminals can withstand along the thickness direction after connection is greater than 2000 N, the internal resistance of the terminal structure is less than 0.035 mΩ, the connection strength of the terminal structure is high, and the current carrying capacity is met, resulting in good sealing performance of the single cell. In Examples 13 and 14, when (h2-h) / h is greater than 1, the ultimate thrust that the first and second terminals can withstand along the thickness direction after connection increases, the internal resistance of the terminal structure increases, the connection strength of the terminal structure improves, but the current carrying capacity decreases. In Examples 15 and 16, when (h2-h) / h is less than 0.5, the ultimate thrust that the first and second poles can withstand along the thickness direction decreases, and the internal resistance is below 0.035mΩ, satisfying the overcurrent capability, but the connection strength of the pole structure decreases. In Examples 17 and 18, when h1 / h is less than 0.8, the ultimate thrust that the first and second poles can withstand along the thickness direction decreases, and the internal resistance is below 0.035mΩ, satisfying the overcurrent capability, but the connection strength of the pole structure decreases. In Examples 19 and 20, when h1 / h is greater than 1.5, the ultimate thrust that the first and second poles can withstand along the thickness direction increases, the internal resistance of the pole structure increases, and the connection strength of the pole structure improves, but the overcurrent capability decreases.

[0056] Please see Figure 5As shown, in some embodiments, the groove has a minimum dimension c along the horizontal direction of the cover plate assembly, satisfying 3.5mm ≤ c ≤ 20mm. It should be understood that by limiting the minimum horizontal dimension c of the groove to the range of 3.5mm to 20mm, suitable space is provided for welding operations. This ensures that welding tools or solder can smoothly enter the groove for welding the first main body and the connecting part, ensuring the welding quality of the second welded part. Simultaneously, it avoids the groove being too large, which would weaken the structural strength of the connecting part, and prevents excessive solder from flowing in, ensuring the stability and controllability of the welding process. A larger groove size can increase the heat dissipation area of ​​the second electrode post, facilitating heat dissipation during battery operation and preventing localized overheating from affecting battery performance. At the same time, a reasonable size also considers the structural stability of the connecting part, ensuring heat dissipation while enabling the second electrode post to withstand internal battery pressure and external vibration and impact, ensuring the reliability of the battery structure. Furthermore, the size of the groove facilitates mold manufacturing and product assembly, reducing manufacturing difficulty and cost.

[0057] Please see Figure 4 As shown, in some embodiments, the through-hole has a riveting hole at the end opposite to the first main body. The diameter of the riveting hole is R, and the depth is H, satisfying: 1.5mm ≤ R ≤ 5mm, 0.1mm ≤ H ≤ 1mm. It should be understood that by setting the diameter R and depth H of the riveting block to meet the above range, the through-hole is riveted into the through hole, achieving effective riveting without excessively weakening the structural strength of the through-hole, further enhancing the connection reliability between the through-hole and the connecting part. By pre-riveting, the through-hole is fixed in the through hole to ensure the alignment of the first pole and the second pole, ensuring the connection reliability and stability between the first pole and the second pole. Specifically, the diameter R can be any value or a range between two values ​​from 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, and 5.0mm. The hole depth H can be any value from 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, and 1mm, or a range between two values. The larger the hole diameter R and the larger the hole depth H, the greater the deformation in the area near the riveting hole of the through-hole, and the greater the fixing force between the through-hole and the hole wall.

[0058] Please see Figure 6As shown, in some embodiments, the cross-section of the through-hole and the through-part along the horizontal direction of the cover assembly is any one of a circle, an ellipse, or a polygon. It should be understood that if the cross-section of the through-hole and the through-part is circular, it allows for quick insertion and connection of the first and second terminals, improving assembly efficiency. Simultaneously, the circular structure better disperses stress, reducing the risk of weld cracking or terminal damage caused by stress concentration, thus ensuring the stability and reliability of the battery. If the cross-section of the through-hole and the through-part is elliptical, it effectively prevents relative rotation between the first and second terminals, ensuring the stability of the cover assembly structure. If the cross-section of the through-hole and the through-part is polygonal, the polygon can be square, rhomboid, or other shapes, which will not be elaborated 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 guide the stress in a specific direction, reducing direct impact on the welded parts and improving the battery's impact resistance.

[0059] Please see 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 segment and a second segment connected together. The first segment is sandwiched between the first main body and the cover body, and the second segment 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 segment away from the connection portion. It should be understood that by arranging the first and second seals to achieve a double sealing structure, electrolyte leakage is effectively blocked, and external air, moisture, and other impurities are prevented from entering the battery, greatly improving the battery's sealing and protection performance and extending its service life. At the same time, the two seals not only play a sealing role but also disperse stress between the terminals and the cover body. When the battery is working, it will undergo thermal expansion and contraction due to charging and discharging. When subjected to external forces such as vibration and impact, the seals can buffer these stresses, avoiding stress concentration at the connection between the terminals and the cover body, preventing the terminals from loosening or the cover from cracking due to excessive stress, and enhancing the structural stability of the entire cover assembly. The layout design of the first and second seals makes reasonable use of the internal space of the cover plate assembly, reduces space utilization, helps maintain the compact internal structure of the battery, facilitates the layout of other internal components of the battery, and is conducive to the miniaturization and lightweight design of the battery.

[0060] This application also discloses a manufacturing process for a single-cell battery. Based on the single-cell battery described in the above embodiments, the process includes the following steps: assembling a cover plate assembly; welding the contact surfaces of the through-hole portion and the connecting portion using seam welding; and welding the bottom wall of the connecting portion and the first main body portion within a sink using through welding. It should be understood that seam welding initially constructs a connection structure between the first and second electrode posts, establishing preliminary positioning and creating a first seal. This prevents relative displacement between the connecting portion and the first main body portion under welding stress, strengthens the fixing relationship between the first and second electrode posts, enhances the single-cell battery's ability to resist external forces such as vibration and impact during use, effectively prevents electrode post loosening, and ensures the stability of battery performance. Then, through welding is used to construct a second seal, improving the overall sealing performance of the single-cell battery. The structural stability after seam welding helps improve the quality of the through welding. Seam welding ensures a tight fit between the through-hole portion and the connecting portion. During through welding, heat can be more evenly distributed between the bottom wall of the connecting portion and the first main body portion. This uniform heat distribution is beneficial for forming a higher quality weld and reducing welding defects such as porosity and cracks. At the same time, pre-welding can remove some impurities from the contact surface, making the welding area cleaner during penetration welding, further improving welding quality, ensuring good electrical connection between the terminals, 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 through-hole portion and the connecting portion; and after riveting, performing seam welding and through-welding. It is important to understand that by positioning and riveting the through-hole portion and the connecting portion before seam welding, the precise position of both before welding is ensured. The stable structure after positioning and riveting facilitates smooth seam welding, prevents misalignment of the through-hole portion and the connecting portion during welding, and ensures that the weld seam is evenly distributed along the preset contact surface, improving welding quality. Positioning and riveting provides a clear reference for subsequent welding, eliminating the need for workers to repeatedly adjust the component position during seam welding and through-welding, reducing operational steps, improving work efficiency, and lowering the product defect rate.

[0062] This application also discloses a battery pack comprising a single battery cell as described in the above embodiments. Therefore, it can possess all the technical features and effects of the aforementioned single battery cell, which will not be repeated here.

[0063] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0064] The foregoing has provided a detailed description of a single-cell battery, a battery pack, and their manufacturing process as provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A single-cell battery, characterized in that, Includes a cover plate assembly, the cover plate assembly comprising: The cover plate body has assembly holes; The first pole post includes a through portion and a first main body portion. The first main body portion is disposed on one side of the cover plate body along the thickness direction. The through portion is connected to the first main body portion and at least partially protrudes into the assembly hole. The second pole post includes a connecting part and a second main body part. The second main body part is disposed on the side of the cover plate body away from the first main body part. The connecting part is connected to the first main body part and at least partially protrudes into the assembly hole and abuts against the first main body part. The connecting part has a through hole along the thickness direction, and the through part passes through the through hole. The through portion is welded to the connecting portion to form a first weld portion; The first main body is welded to the connecting part and a second welded part is formed thereon; The connecting part has a thickness dimension h, the first welding part has a penetration depth dimension h1, and the second welding part has a penetration depth dimension h2, satisfying: 0.5mm≤h≤1.5mm, 0.8≤h1 / h≤1.5, 0.5≤(h2-h) / h≤1; The first weld has a weld width w1, which satisfies 0.3mm≤w1≤2mm, and the second weld has a weld width w2, which satisfies 1.5mm≤w2≤5mm. The cover plate assembly further includes a first sealing element and a second sealing element. The first sealing element includes a first segment and a second segment connected together. The first segment is sandwiched between the first main body and the cover plate body, and the second segment is sandwiched between the first main body and the second main body. The second sealing element is sandwiched between the cover plate body and the second main body, and is located on the side of the second section away from the connecting part; Along the horizontal direction of the cover plate assembly, the distance between the through portion and the wall of the through hole has a minimum dimension d, satisfying 0.05mm≤d≤0.2mm.

2. The single-cell battery according to claim 1, characterized in that, The second pole post has a groove on the side opposite to the first main body, and the groove is connected to the through hole.

3. The single-cell battery according to claim 2, characterized in that, The connecting portion includes a bottom wall and a side wall connected together. The bottom wall abuts against the first main body portion, and the side wall is connected around the bottom wall on the side away from the first main body portion. The bottom wall and the side wall form the sinkhole, and the second main body portion is connected around the side wall on the side away from the sinkhole.

4. The single-cell battery according to claim 2, characterized in that, Along the horizontal direction of the cover plate assembly, the sink has a minimum dimension c, satisfying 3.5mm≤c≤20mm.

5. The single-cell battery according to claim 1, characterized in that, The through-hole has a rivet hole at one end away from the first main body. The diameter of the rivet hole is R and the depth is H, satisfying: 1.5mm≤R≤5mm, 0.1mm≤H≤1mm.

6. The single-cell battery according to claim 1, characterized in that, The cross-section of the through 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.

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