Battery, battery pack, and electric device

Abstract

This disclosure provides a battery, a battery pack, and an electrical device. The battery includes a casing and a cover plate. A receiving cavity is formed within the casing. The casing has a predetermined surface, and the receiving cavity forms an opening on the predetermined surface. A predetermined gap exists between the cover plate extending into the receiving cavity and the side wall of the casing. The cover plate is welded to the casing to close the opening, and a weld mark is formed at the weld joint between the cover plate and the casing. Along a third direction, the maximum dimension of the weld mark covering the predetermined gap is D mm; along a first direction or a second direction, the maximum dimension of the weld mark is G mm, and the maximum spacing of the predetermined gap is L1 mm, where 0.9 ≤ (D × G) / L1 ≤ 260. Compared with related technologies, this disclosure adapts the bearing area of ​​the weld mark to the assembly gap between the casing and the cover plate, reducing stress concentration at the short-side weld mark of the battery under vibration or impact conditions, preventing cracking of the short-side weld mark, and improving the structural stability of the battery.

Description

Technical Field

[0001] This disclosure relates to the field of battery technology, and in particular to a battery, a battery pack, and an electrical device. Background Technology

[0002] In related technologies, the battery includes a casing and a cover plate. The casing has a cuboid structure and a cavity is formed inside the casing to accommodate the battery cell and electrolyte. The casing has an opening at its end. The cover plate is connected to the casing by welding to close the opening. A weld mark is formed at the welded connection between the cover plate and the casing.

[0003] In practical applications, batteries are arranged in an array to form battery packs. The larger surfaces of adjacent rows of batteries are positioned opposite each other to create mutual constraint, which can effectively reduce the vibration amplitude of the batteries under vibration or impact conditions. However, this constraint mainly acts on the long side solder marks corresponding to the large surface of the battery, while the short side solder marks are not effectively constrained. Under long-term vibration and tearing conditions, the solder marks are prone to failure, leading to leakage problems. Summary of the Invention

[0004] The purpose of this disclosure is to provide a battery, battery pack, and electrical device to solve the technical problems in the related art, which can improve the tensile strength of short-side solder marks and prevent short-side solder marks from cracking.

[0005] In a first aspect, this disclosure provides a battery, including a housing and a cover plate. The housing has a receiving cavity formed therein. The housing has a predetermined surface with a long side extending along a first direction and a short side extending along a second direction. The first direction, the second direction, and the third direction are all perpendicular to each other. The receiving cavity forms an opening on the predetermined surface. At least a portion of the cover plate extends into the receiving cavity through the opening. A predetermined gap exists between the cover plate extending into the receiving cavity and the side wall of the housing. The cover plate is welded to the housing to close the opening. A weld mark is formed at the welded connection between the cover plate and the housing. Along the third direction upward, the maximum size of the solder mark covering the preset gap is Dmm; along the first direction or the second direction, the maximum size of the solder mark is Gmm, and the maximum spacing of the preset gap is L1mm, where 0.9≤(D×G) / L1≤260.

[0006] In a second aspect, this disclosure provides a battery pack including at least two batteries as described above, the at least two batteries being arranged along the second direction.

[0007] Thirdly, this disclosure provides an electrical device including the aforementioned battery pack.

[0008] Compared with related technologies, this disclosure satisfies the following relationship: the maximum size D of the weld mark covering the preset gap along the normal direction of the preset surface of the shell, the maximum size G of the weld mark along the long or short side, and the maximum distance L1 between the outer wall surface of the cover plate and the inner wall surface of the shell: 0.9 ≤ (D×G) / L1 ≤ 260. This ensures that the bearing area of ​​the weld mark is adapted to the assembly gap between the shell and the cover plate, reducing stress concentration at the short side weld mark of the battery under vibration or impact conditions, preventing cracking of the short side weld mark, improving the structural stability of the battery, and simultaneously preventing the melting of the internal insulation components of the battery during the welding process, thus reducing the risk of short circuits in the internal insulation components of the battery. Attached Figure Description

[0009] Figure 1 This is a perspective view of the battery provided in an embodiment of this disclosure.

[0010] Figure 2 This is a perspective view of the battery casing provided in an embodiment of this disclosure.

[0011] Figure 3 yes Figure 1 A top view of the provided battery.

[0012] Figure 4 yes Figure 3 A sectional view along line AA.

[0013] Figure 5 yes Figure 4 A magnified structural diagram of point B, which has one of its annotation forms.

[0014] Figure 6 yes Figure 4 A magnified structural diagram of point B with another labeling format.

[0015] Explanation of reference numerals in the attached figures: 1-Shell, 2-Cover plate, 3-Receiving cavity, 4-Opening, 5-Preset surface, 51-Long side, 52-Short side, 6-Preset gap, 7-Weld mark, 8-Cavity; D1 - First direction, D2 - Second direction, D3 - Third direction. Detailed Implementation

[0016] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this disclosure, and should not be construed as limiting this disclosure.

[0017] Reference Figures 1 to 6As shown, this disclosure provides a battery, including a housing 1 and a cover plate 2 covering the housing 1. The housing 1 and the cover plate 2 together constitute the outer shell of the battery. In one feasible embodiment, the outer shell of the battery is a cuboid structure. To better illustrate the structure of the battery, this disclosure defines a three-dimensional rectangular coordinate system, defining the direction of the long side 51 of the top surface of the battery as the first direction D1, the direction of the short side 52 of the top surface of the battery as the second direction D2, and the height direction of the battery as the third direction D3. The first direction D1, the second direction D2, and the third direction D3 are perpendicular to each other.

[0018] A receiving cavity 3 is integrally formed within the housing 1. The receiving cavity 3 is used to accommodate the battery cells and electrolyte. The housing 1 has a predetermined surface 5, which has a long side 51 extending along a first direction D1 and a short side 52 extending along a second direction D2. The normal direction of the predetermined surface 5 is the third direction D3. Among the multiple batteries constituting the battery pack, the multiple batteries are arranged in an array along the second direction D2, with the large surfaces of adjacent batteries in contact. The receiving cavity 3 forms an opening 4 on the predetermined surface 5. The opening 4 is a through area of ​​the receiving cavity 3 on the predetermined surface 5. The shape of the opening 4 matches the shape of the cover plate 2. The battery cells and electrolyte and other components are assembled into the receiving cavity 3 through the opening 4.

[0019] At least a portion of the cover plate 2 extends into the receiving cavity 3 through the opening 4 to form a nested fit. In one feasible embodiment, the cross-section of the cover plate 2 along the third direction D3 is a "T"-shaped structure or a flat plate structure, and there is a predetermined gap 6 between the cover plate 2 extending into the receiving cavity 3 and the side wall of the housing 1. The cover plate 2 is welded to the housing 1 to close the opening 4, connecting the cover plate 2 and the housing 1 into an integral structure and closing the predetermined gap 6 between the cover plate 2 and the housing 1. The welding direction can be top welding or side welding. Top welding can avoid excessive weld line size on the side wall of the housing 1, which may lead to the risk of weld penetration or breakage of the side wall of the housing 1. The thickness of the cover plate 2 is generally greater than the thickness of the housing 1. Top welding better ensures the welding strength of the weld line and improves the welding rate. The penetration direction can also be parallel to the large surface of the cover plate 2, that is, forming a side weld, to avoid the risk of weld line cracking during battery vibration, where the vibration direction is parallel to the penetration direction.

[0020] The cover plate 2 and the shell 1 are joined by laser welding to form a weld mark 7. The weld mark 7 is located at the welding interface between the cover plate 2 and the shell 1. The high temperature during welding melts the metal materials of the cover plate 2 and the shell 1 to form a molten pool. The molten pool fills the preset gap 6 between the cover plate 2 and the shell 1 and then solidifies to form the weld mark 7. The weld mark 7 can connect the cover plate 2 and the shell 1 into a whole and disperse the stress generated by the battery under vibration or impact conditions.

[0021] In the embodiments disclosed herein, the maximum size of the weld mark 7 covering the preset gap 6 along the normal direction (i.e., the third direction D3) of the preset surface 5 is D mm, where D is the effective penetration depth of the weld mark 7. The value of D affects the structural strength of the welded connection. A suitable D size can ensure that the weld mark 7 forms a sufficient bonding depth, avoid defects such as incomplete welding and lack of fusion, and improve the tensile and impact resistance of the welded connection. Preferably, this maximum size is set at the short side 52 of the preset surface 5, and is limited to 0.3 ≤ D ≤ 1.4. The value can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, or 1.4. The value can specifically be one of the aforementioned values, or any value between 0.3 and 1.4. Within this preset value range, the larger D is, the stronger the ability of the solder mark 7 to disperse and transfer stress. When it exceeds the preset value range, the depth of D is too large, which leads to the burning through of the cover plate 2, excessive welding heat, melting of the internal insulation components of the battery, and the risk of insulation short circuit between the cover plate 2 and the cell.

[0022] The insulating component is disposed between the electrode post and the lower surface of the battery casing 1 to insulate the electrode post (electrode terminal) from the lower surface (or bottom surface) of the battery casing 1, and to insulate the battery cell from the cover plate 2, thereby reducing the risk of short circuit.

[0023] The insulating component can be made of plastic, rubber, or other insulating materials. The plastic can be polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), or polyvinyl chloride (PVC). The rubber can be fluororubber, nitrile rubber, or isobutyl rubber.

[0024] Along the first direction D1 or the second direction D2, the maximum dimension of the weld mark 7 is G mm, where G is the weld width. The value of G affects the structural strength of the welded connection. A suitable G dimension can increase the load-bearing area of ​​the weld mark 7 and improve the tensile and impact resistance of the welded connection. Preferably, this maximum dimension is limited to the short side 52 of the preset surface 5, and is limited to 0.5 ≤ G ≤ 2. The value can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2. The value can be specifically the values ​​listed above, or any value between 0.5 and 2. Within this preset value range, the larger G is, the larger the area of ​​the weld mark 7 that bears the mechanical load, and the more uniform the stress distribution. After exceeding the preset value range, the width of G becomes too large, leading to an expansion of the weld heat-affected zone, causing welding deformation of the shell 1 and the cover plate 2, and reducing the structural strength of the shell 1 and the cover plate 2.

[0025] The spaced arrangement between the side of the cover plate 2 and the side wall of the housing 1 ensures that the cover plate 2 can be quickly inserted into the housing 1, improving the overall assembly efficiency of the battery and ensuring reliable welding dimensions. However, the preset gap 6 causes the molten pool to move slowly during the welding process, resulting in a straight line segment at the edge of the weld line. This stress concentration causes the weld line between the cover plate 2 and the housing 1 to crack, creating internal and external electrical connections within the battery and posing a safety risk of thermal runaway. The maximum spacing of the preset gap 6 is L1, which is the maximum distance between the outer wall of the extended portion of the cover plate 2 and the inner wall of the receiving cavity 3. A suitable L1 size can provide sufficient filling space for the molten pool, ensuring that the molten pool can completely fill the preset gap 6 and avoiding defects such as incomplete welding and lack of fusion. Preferably, this maximum gap occurs at the short side 52 of the preset surface 5, limited to 0.01≤L1≤0.2. The value can be 0.01, 0.03, 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, or 0.2. The value can be one of the values ​​listed above, or any value between 0.01 and 0.2. Within this preset value range, the molten pool has sufficient filling space and can completely fill the preset gap 6. Beyond this range, the molten pool is insufficiently filled, resulting in decreased welding quality. If the preset gap 6 is too large, stress concentration at the weld joint occurs, increasing the risk of cracking.

[0026] In the embodiments provided in this disclosure, the relationship 0.9 ≤ (D×G) / L1 ≤ 260 is defined. The value can be 0.9, 1.8, 5, 10, 40, 70, 90, 100, 120, 150, 180, 200, 230, 240, or 260. Specifically, the value can be one of the aforementioned values ​​or any value between 0.9 and 260. Limiting this relationship to a preset numerical range ensures that the molten pool can completely fill the preset gap 6, improving the strength of the weld 7, while also avoiding stress concentration caused by the mismatch between the weld 7 size and the preset gap 6. This effectively solves the problem of tearing failure of the short-side 52 weld 7 under vibration or impact conditions.

[0027] If the value of the relation is too small, the effective bearing area of ​​the weld 7 will be too small, or the preset gap 6 between the shell 1 and the cover plate 2 will be too large. The molten pool cannot fully fill the preset gap 6, resulting in insufficient welding connection strength. The weld 7 at the short side 52 of the battery is prone to cracking under vibration and tearing, causing sealing failure.

[0028] If the value of the relation is too large, the effective bearing area of ​​the weld 7 will be too large, or the preset gap 6 between the shell 1 and the cover plate 2 will be too small, resulting in the continuous accumulation of welding heat, melting of the internal insulation components of the battery, and internal short circuit, which may lead to the risk of battery insulation failure.

[0029] In one feasible implementation, along the third direction D3, the distance by which the cover plate 2 extends into the receiving cavity 3 is H mm, limited to 1.5 ≤ H ≤ 3. The value can be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3. The value can specifically be one of the aforementioned values, or any value between 1.5 and 3. If H is too small, the mating area between the cover plate 2 and the shell 1 will be insufficient, affecting the welding strength and structural stability; if H is too large, it will interfere with the battery cells inside the battery. In the embodiments provided in this disclosure, the thickness of the shell 1 is limited to between 0.45 mm and 1.5 mm, and the thickness of the cover plate 2 is limited to between 1 mm and 3 mm.

[0030] The relationship is defined as follows: 0.167 ≤ D / H ≤ 0.867. The value can be 0.167, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.867. The value can be one of the listed values ​​or any value between 0.167 and 0.867. Limiting this relationship to a preset range ensures that the stress on the solder joint 7 is effectively dispersed.

[0031] If this relationship is too small, the depth of the cover plate 2 is excessive relative to the effective penetration depth of the weld 7. After reaching the required effective penetration depth, the area of ​​the cover plate 2 not covered by welding is too large. These areas are not sufficiently fixed by the weld 7, generating additional stress under vibration or impact conditions. This also increases the risk of the short side 52 weld 7 tearing and failing under vibration or impact conditions.

[0032] If this relationship is too large, the depth of the cover plate 2 is insufficient relative to the effective penetration depth of the weld 7. After reaching the required effective penetration depth, the area of ​​the cover plate 2 not covered by welding is too small, and the stress on the weld 7 cannot be effectively dispersed, resulting in stress concentration at the weld 7. This increases the risk of the weld 7 on the short side 52 tearing and failing under vibration or impact conditions.

[0033] Furthermore, the relationship is limited to 0.25 ≤ (D×G) / (H×L1) ≤ 186.7. The value can be 0.25, 1, 10, 40, 70, 90, 100, 120, 150, 180, or 186.7. The value can be one of the aforementioned listed values ​​or any value between 0.25 and 186.7. Limiting this relationship to a preset numerical range ensures that the weld 7 has sufficient bearing area and penetration depth to resist tearing stress; it also provides suitable depth of cover plate 2 for stable support, preventing stress concentration in the weld 7; and simultaneously ensures that the molten pool fully fills the preset gap 6, avoiding defects such as incomplete welding and lack of fusion.

[0034] If this relationship is too small, the weld mark 7 will not have sufficient bearing area and penetration depth, and will not be able to effectively resist vibration and tearing; or the area of ​​the cover plate 2 not covered by welding will be too large or the preset gap 6 will not be fully filled, so that the cover plate 2 will not be fully fixed by the weld mark 7, generating additional stress under vibration or impact conditions, increasing the risk of the weld mark 7 at the short side 52 tearing failure under vibration or impact conditions.

[0035] If this relationship is too large, the heat-affected zone of the weld mark 7 will expand, causing welding deformation of the shell 1 and the cover plate 2, and reducing the structural strength of the shell 1 and the cover plate 2; or if the area of ​​the cover plate 2 not covered by welding is too small, the stress on the weld mark 7 cannot be effectively dispersed, causing stress concentration at the weld mark 7, which also increases the risk of the weld mark 7 at the short side 52 tearing failure under vibration or impact conditions.

[0036] In the embodiments provided in this disclosure, the maximum distance between the edge of the solder mark 7 located outside the battery and the cover plate 2 along the third direction D3 is R mm. Preferably, this maximum distance is located at the short side 52 of the preset surface 5, and is limited to 0.01 ≤ R ≤ 0.3. The value can be 0.01, 0.03, 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28 or 0.3, and can specifically be the values ​​listed above, or any value between 0.01 and 0.3. If R is too small, the thickness of the solder mark 7 is insufficient, the effective bearing area of ​​the solder mark 7 is reduced, and it cannot effectively disperse and transmit the tearing stress generated under vibration or impact conditions, resulting in stress concentration of the solder mark 7 on the short side 52, which is prone to cracking. If R is too large, the solder mark 7 will be too thick, which will affect the coating of the blue film on the battery surface, resulting in insufficient adhesion of the blue film and easy detachment of the blue film. At the same time, if the welding time is too long, too much welding heat will be continuously input, causing deformation of the shell 1 or cover plate 2, which will increase the risk of failure of the short side 52 solder mark 7.

[0037] The relationship is defined as: 0.05≤R / L1≤30. The values ​​can be 0.05, 0.1, 0.5, 1, 5, 10, 15, 20, 25 or 30. The values ​​can be the ones listed above or any value between 0.05 and 30.

[0038] If this relationship is too small, the thickness of the weld 7 will be insufficient, or the preset gap 6 between the cover plate 2 and the shell 1 will be too large, resulting in a reduction in the effective bearing area of ​​the weld 7, insufficient filling of the molten pool, and defects such as incomplete fusion inside the weld 7. It will be unable to effectively transmit and disperse the tearing stress that occurs under vibration or impact conditions, resulting in stress concentration on the short side 52 weld 7, which is prone to cracking. If the preset gap 6 is too large, the stress at the weld will be concentrated, and the risk of cracking will be greater.

[0039] If this relationship is too large, the solder mark 7 will be too thick, or the preset gap 6 between the cover plate 2 and the shell 1 will be too small. Excessive molten pool filling will increase the welding heat input, causing the welding heat to accumulate continuously, melting the internal insulation components of the battery, and causing an internal short circuit that could lead to battery insulation failure.

[0040] In the embodiments provided in this disclosure, the maximum distance between the edge of the solder mark 7 and the housing 1 along the first direction D1 or the second direction D2 is T mm. Preferably, this maximum distance is defined at the short side 52 of the preset surface 5, and is defined as 0 ≤ T ≤ 0.15. The value can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15. The value can be specifically the values ​​listed above, or any value between 0 and 0.15. If T is too small, the thickness of the solder mark 7 will be insufficient, the effective bearing area of ​​the solder mark 7 will be reduced, and it will be unable to effectively disperse and transmit the tearing stress generated under vibration or impact conditions, resulting in stress concentration at the short side 52 of the solder mark 7, which is prone to cracking. If T is too large, the solder mark 7 will be too thick, which will affect the coating of the blue film on the battery surface, resulting in insufficient adhesion of the blue film and easy detachment of the blue film. At the same time, if the welding time is too long, too much welding heat will be continuously input, causing deformation of the casing 1 and increasing the risk of failure of the solder mark 7 at the short side 52.

[0041] In the embodiments provided in this disclosure, the lowest point of the solder mark 7 on the third direction D3 is misaligned with the preset gap 6, thereby avoiding the problem of laser light leakage during the welding process. During the process of forming the solder mark 7 using laser welding, if the lowest point of the solder mark 7 coincides with the preset gap 6, the laser energy may pass through the preset gap 6 and directly act on the internal battery cell, causing damage to the battery cell.

[0042] By misaligning the lowest point of the solder mark 7 with the preset gap 6 in the third direction D3, the laser energy can be mainly applied to the housing 1 or the cover plate 2. This ensures that the molten pool fully fills the preset gap 6 to form a reliable solder mark structure, while preventing the laser from penetrating the preset gap 6 and soldering to the battery cell, thus avoiding damage.

[0043] In the embodiments provided in this disclosure, the maximum cross-sectional area of ​​the solder mark 7 along the first direction D1 or the second direction D2 is S mm. 2Preferably, this maximum cross-sectional area is located at the short side 52 of the preset surface 5, and is limited to 0.6 ≤ S ≤ 1.7. The value can be 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, or 1.7. The value can be one of the aforementioned values ​​or any value between 0.6 and 1.7. If the maximum cross-sectional area is too small, the bearing area of ​​the weld mark 7 is insufficient, failing to effectively transfer and disperse the tearing stress caused by vibration or impact, leading to stress concentration at the weld mark 7 and increasing the risk of cracking. If the maximum cross-sectional area is too large, the cross-sectional area of ​​the weld mark 7 is excessive, expanding the welding heat-affected zone, causing continuous accumulation of welding heat, melting of the internal insulation components of the battery, and internal short circuits leading to battery insulation failure.

[0044] In one feasible implementation, both the cover plate 2 and the shell 1 are made of aluminum, which can be pure aluminum or aluminum alloy. Compared with steel, the aluminum cover plate 2 and shell 1 have lower strength, resulting in weaker structural stability and tear resistance in the welded joint area. Therefore, it is necessary to ensure that the weld 7 has sufficient strength to offset the weakening effect caused by the material, thereby increasing the lower limit of the relationship: 1.8 ≤ (D×G) / L1 ≤ 260. The value can be 1.8, 10, 40, 70, 90, 100, 120, 150, 180, 200, 240, or 260. The value can be one of the aforementioned values ​​or any value between 1.8 and 260. By increasing the effective penetration depth or width of the weld 7, or by reducing the preset gap 6 between the cover plate 2 and the shell 1, it is ensured that the weld 7 has sufficient strength and that the molten pool can fully fill the preset gap 6, thereby improving the tear resistance of the weld 7 and reducing the risk of cracking.

[0045] In another feasible implementation, both the cover plate 2 and the shell 1 are made of steel, which has higher strength than aluminum. This results in higher structural stability and tear resistance in the welded joint area, eliminating the need to increase the area of ​​the weld mark 7 to improve connection reliability. Therefore, the upper limit of the relationship can be reduced: 0.9 ≤ (D×G) / L1 ≤ 240. The value can be 0.9, 1.8, 10, 40, 70, 90, 100, 120, 150, 180, 200, or 240. The value can be any of the values ​​listed above or any value between 0.9 and 240. This reduces the effective penetration depth or width of the weld mark 7, decreasing the welding heat input and preventing thermal deformation of the shell 1 and cover plate 2 due to excessive heat input. Simultaneously, it does not affect the sufficient filling of the preset gap 6 by the molten pool.

[0046] In the embodiments provided in this disclosure, the minimum distance between the outer wall surface of the cover plate 2 extending into the receiving cavity 3 and the inner wall surface of the receiving cavity 3 is L2mm, where L1-L2≤0.05. The value can be 0, 0.01, 0.02, 0.03, 0.04, or 0.05, specifically the values ​​listed above, or any value between 0 and 0.05. This relationship limits the maximum fluctuation range of the preset gap 6, ensuring that the preset gap 6 between the cover plate 2 and the shell 1 is evenly distributed, avoiding the preset gap 6 being too large or too small, ensuring uniform filling of the molten pool during welding, and avoiding defects such as incomplete welding or lack of fusion caused by fluctuations in the preset gap 6. If the relationship exceeds the limited range, the fluctuation of the preset gap 6 is too large, resulting in insufficient filling of the molten pool in areas with excessively large preset gap 6, reducing the connection strength.

[0047] In the embodiments provided in this disclosure, the battery is defined as a flat block structure. The area where the short side 52 is located has higher requirements for the load-bearing capacity of the solder 7. The ratio of the length of the short side 52 to the length of the long side 51 is defined as greater than or equal to 0.1, and the value can be 0.1, 0.2, 0.3, 0.4, 0.5 or a larger value. The value can be specifically the values ​​listed above, or any value greater than or equal to 0.1. Controlling the difference between the short side 52 and the long side 51 of the battery within a certain range can reduce the stress concentration in the welding area of ​​the short side 52 to a certain extent.

[0048] Based on this structure, at the short side 52 of the preset surface 5, the relationship is defined as follows: (D×G) / L1≥10. The value can be 10, 20, 30, 40, 50, or larger. The value can be one of the aforementioned listed values ​​or any value greater than or equal to 10. Since the welding area on the short side 52 of the flat battery is more susceptible to vibration or impact, the weld 7 is more prone to cracking. Therefore, increasing the upper limit of the relationship ensures that the weld 7 has sufficient effective penetration depth and width.

[0049] In the embodiments provided in this disclosure, since the gas is not discharged in time during the solidification of the molten pool, a cavity 8 is formed in the solder mark 7. Along the third direction D3, the orthographic projection of the cavity 8 at least partially falls within the preset gap 6. The maximum size of the cavity 8 is K mm, where 0.03 ≤ K ≤ 0.5. The value can be 0.03, 0.05, 0.07, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, or 0.5. The value can specifically be one of the aforementioned values, or any value between 0.03 and 0.5.

[0050] The relationship is defined as 0.15 ≤ K / L1 ≤ 30. The values ​​can be 0.15, 0.5, 1, 3, 5, 7, 10, 13, 15, 17, 20, 23, 25, 27, or 30. These values ​​can be specifically listed above or any value between 0.15 and 30. Within this preset range, while allowing for minor cavities 8, it avoids excessively large cavities 8 that could reduce the structural strength and tear resistance of the solder mark 7.

[0051] If this ratio is too small, it will impose excessive requirements on the volume of cavity 8. The tiny cavity 8 has a limited impact on the performance of solder mark 7 and does not need to be excessively constrained. Although a ratio that is too small can ensure the integrity of solder mark 7 to the greatest extent, it will increase the requirements for welding process and increase production costs.

[0052] If this ratio is too large, the size of cavity 8 will be too large, which will significantly weaken the effective bearing area of ​​solder 7, resulting in a decrease in the structural strength and tear resistance of solder 7. Under vibration or impact conditions, solder 7 is prone to cracking from cavity 8, damaging the battery sealing performance and causing electrolyte leakage.

[0053] In one feasible implementation, along the third direction D3, the minimum distance between the lowest point of the solder mark 7 on the third direction D3 and the cavity 8 is ≥0.01mm. The value can be 0.01, 0.02, 0.03, 0.03, 0.04, 0.05, 0.1, 0.5 or larger, and the value can be specifically the values ​​listed above, or any value greater than or equal to 0.01.

[0054] The minimum spacing is limited to a preset range to prevent the cavity 8 from being too close to the lowest point of the weld 7, which would result in insufficient effective load-bearing thickness at the bottom of the weld 7. If the cavity 8 is too close to the lowest point of the weld 7, it will weaken the structural strength of the lowest point of the weld 7, and the weld 7 will be prone to cracking under vibration or impact conditions.

[0055] Along the third direction D3, the minimum distance between the lowest point of the weld 7 on the third direction D3 and the cavity 8 is between 0.01mm and 0.5mm, and the value can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, or 0.5. The value can specifically be one of the values ​​listed above, or any value between 0.01 and 0.5. This avoids the cavity 8 being too close to the bottom of the weld 7, resulting in insufficient effective load-bearing thickness, while also preventing excessive accumulation of the weld pool due to an excessively large distance. Where K ≤ 0.4, the value can be 0.1, 0.2, 0.3, or 0.4. The value can specifically be one of the values ​​listed above, or any value less than or equal to 0.4.

[0056] Furthermore, since the air bubbles are located in the critical welding area of ​​the preset gap 6, they disrupt the continuity of the weld 7, reducing its effective load-bearing area and causing a decrease in structural strength and tear resistance. Therefore, the value is limited to 5 ≤ (D×G) / L1 ≤ 230. This value can be 5, 10, 40, 70, 90, 100, 120, 150, 180, 200, or 230, specifically the values ​​listed above, or any value between 5 and 230. By increasing the effective penetration and width of the weld 7, the effective load-bearing area of ​​the weld 7 is expanded, while the size of the preset gap 6 is reduced, allowing the molten pool to be fully filled, ensuring sufficient strength for the weld 7, thereby improving its tear resistance and reducing the risk of cracking.

[0057] In another feasible implementation, the orthographic projection of the cavity 8 is offset from the preset gap 6, avoiding the main stress area of ​​welding and minimizing damage to the structural strength of the weld 7. Therefore, the value is limited to 0.9 ≤ (D×G) / L1 ≤ 240. The value can be 0.9, 5, 10, 40, 70, 90, 100, 120, 150, 180, 200, or 240, specifically the values ​​listed above, or any value between 0.9 and 240. This reduces the effective penetration depth or width of the weld 7, decreasing the welding heat input and preventing excessive heat accumulation that could melt the internal insulation components of the battery, leading to internal short circuits and battery insulation failure. Simultaneously, it does not affect the sufficient filling of the preset gap 6 by the molten pool.

[0058] Secondly, this disclosure provides a battery pack including at least two batteries as described above, the at least two batteries being arranged along a second direction D2. Because the batteries are stacked along the large surface direction of the batteries in the second direction D2, adjacent batteries are close to each other, creating constraints. This results in weaker constraints on the short side 52 of the predetermined surface 5 of the battery casing 1. Under vibration or impact conditions, stress concentration is more likely to occur at the solder joints at the short side 52, increasing the risk of cracking of the solder joints 7 at the short side 52.

[0059] Furthermore, multiple batteries arranged along the second direction D2 form a battery pack. The ratio of the battery pack's dimension along the second direction D2 to its dimension along the first direction D1 is greater than or equal to 5, and the value can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or a larger value. The value can be specifically the values ​​listed above, or any value greater than 5. The batteries within the battery pack are mainly close to each other and form constraints along the second direction D2. However, the short side of the battery's preset surface 5 is in a state of weak constraint. Under vibration or impact conditions, the weld 7 at the short side 52 is prone to stress concentration, posing a significant risk of cracking.

[0060] Specifically, at the short side of the preset surface 5, the relationship is defined as: (D×G)≥0.3, where the value can be 0.3, 0.5, 1, 1.3, 1.5, 1.8, 2, 2.8, or a larger value. The value can be one of the aforementioned listed values ​​or any value greater than or equal to 0.3. This ensures that the solder mark 7 has sufficient bearing area and penetration depth to resist tearing stress, and that the molten pool fully fills the preset gap 6, avoiding defects such as incomplete soldering and lack of fusion.

[0061] Thirdly, this disclosure provides an electrical device that may include the aforementioned battery pack.

[0062] Battery packs can serve as operating power for electrical equipment or as driving power for electrical equipment, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. By way of example only, electrical equipment can be, but is not limited to, vehicles, ships, aircraft, household appliances, and industrial equipment. For example, vehicles can be passenger cars, trucks, construction vehicles, etc.

[0063] In addition, electrical equipment can also be used for the storage, conversion, and release of recyclable electrical energy.

[0064] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0065] Size measurement methods Use measuring instruments such as micrometers or calipers to measure parameters such as length, width, depth, diameter, radius, distance, and thickness. The area is then calculated using these parameters.

[0066] Battery manufacturing (1) Preparation of the positive electrode: The positive electrode active material, conductive agent acetylene black, and binder PVDF are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, it is cold-pressed and slit to obtain the positive electrode sheet. Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92-98):(4-1):(4-1).

[0067] (2) Preparation of negative electrode: The negative electrode active material, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet is obtained. The ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90-96): (4-2): (2-1): (4-1).

[0068] (3) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0069] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0070] (5) Battery fabrication: The positive electrode, separator, and negative electrode are stacked in sequence and wound to form a bare battery cell, which is then placed in a prismatic battery casing. The battery is dried, injected with electrolyte, sealed with a sealing device, and then subjected to settling, formation, and volume adjustment to obtain the battery.

[0071] The positive electrode active material can be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate; the negative electrode active material can be selected from one or more negative electrode active main materials, such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0072] The adhesive includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0073] The solvent can be deionized water, NMP (N-methylpyrrolidone), alcohol, ether, ketone or other types of pyrrolidone, etc.

[0074] The positive electrode current collector foil can be a metal foil or a composite current collector. For example, as a metal foil, it can be made of stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0075] The negative electrode current collector foil can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium, and can be surface-plated with silver. Composite current collectors may include a polymer base layer and a metal layer. Composite current collectors can be formed by forming metal materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer base material (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0076] In this test, the main active material of the positive electrode was selected from lithium iron phosphate, accounting for 98% of the mass of the positive active material, 0.5% of the conductive agent, and 1.5% of the binder; the active material of the negative electrode was selected from artificial graphite, accounting for 96.5% of the mass of the negative active material, 0.5% of the conductive agent, 0.5% of the thickener, and 2.5% of the binder.

[0077] The testing method is as follows: Test Method 1: Battery leakage rate under vibration conditions According to the above battery preparation method, for each embodiment and comparative example, 500 batteries were prepared, 50 batteries were grouped together, and they were arranged along the width direction of the batteries to form a battery column. The battery columns were then arranged along the length direction of the batteries to form a battery pack. The values ​​of D, G and L1 for each embodiment and comparative example are shown in Table 2 below. All other test conditions remained the same.

[0078] The battery was mounted on a vibration table according to GB / T2423.43. The testing procedure was carried out according to GB / T2423.56. Random and fixed-frequency vibration loads were applied in each direction, and the loading sequence should preferably be random z-axis, fixed-frequency z-axis, random y-axis, fixed-frequency y-axis, random x-axis, fixed-frequency x-axis (the direction of the line connecting the front and rear of the battery is the x-axis direction, and the other horizontal direction perpendicular to the x-axis direction is the y-axis direction). The vibration frequency, power spectral density (PSD), vibration time, etc. are shown in Table 1 below.

[0079] Table 1: After the vibration ends, observe the junction between the short side of the battery cover and the battery casing to see if any leakage occurs. The leakage rate is calculated as (number of batteries that leaked / 100) × 100%.

[0080] If the battery leakage rate is less than or equal to 3%, the test result is considered acceptable; if the battery leakage rate is greater than 3%, it is considered unacceptable.

[0081] Test Method 2: Solder Penetration Test of Insulating Film Following the battery fabrication method described above, 100 corresponding batteries were prepared for each embodiment and comparative example. First, the battery cell was placed into the casing, and the cover plate was welded to the casing using laser welding technology. During the welding process, the welding power was maintained at 2000W, and the welding speed was set to 250mm / s. After welding, the battery was disassembled to check for weld penetration of the insulating film. If weld penetration of the insulating film occurred, the structure was unqualified; otherwise, the result was acceptable.

[0082] The example table is as follows: Table 2: According to the test results in Table 2 above, combined with Examples 1-10, when the formula value of (D×G) / L1 satisfies 0.9≤(D×G) / L1≤260, the bearing area of ​​the solder mark is compatible with the assembly gap between the shell and the cover plate. After testing, under vibration conditions, the welding structure of the short side of the battery is stable and there is no cracking that would lead to battery leakage. After disassembling the battery, no welding penetration was found in the insulating film.

[0083] In Comparative Example 1, (D×G) / L1 is less than 0.9, which means the welding size printed at the preset gap is too small or the preset gap between the cover plate and the side wall of the casing is too large, resulting in low welding strength on the short side of the battery. Under vibration conditions, cracking or leakage may occur. In Comparative Example 2, (D×G) / L1 > 260, which means the welding size printed at the preset gap is too large. During welding, the heat affects the insulating film on the outside of the cell, causing the insulating film to be burned through.

[0084] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of this disclosure. The above description is only a preferred embodiment of this disclosure, but this disclosure does not limit the scope of implementation to what is shown in the figures. Any changes made in accordance with the concept of this disclosure, or modifications to equivalent embodiments with equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of this disclosure.

Claims

1. A battery, characterized in that, The device includes a housing and a cover plate. The housing has a receiving cavity. The housing has a predetermined surface with a long side extending along a first direction and a short side extending along a second direction. The first direction, the second direction, and the third direction are all perpendicular to each other. The receiving cavity has an opening on the predetermined surface. At least a portion of the cover plate extends into the receiving cavity through the opening. There is a predetermined gap between the cover plate extending into the receiving cavity and the side wall of the housing. The cover plate is welded to the housing to close the opening. A weld mark is formed at the welded connection between the cover plate and the housing. Along the third direction upward, the maximum size of the solder mark covering the preset gap is Dmm; along the first direction or the second direction, the maximum size of the solder mark is Gmm, and the maximum spacing of the preset gap is L1mm, where 0.9≤(D×G) / L1≤260.

2. The battery according to claim 1, characterized in that, Along the third direction upwards, the cover plate extends into the receiving cavity by a distance of H mm, where 0.167 ≤ D / H ≤ 0.

867.

3. The battery according to claim 1, characterized in that, Along the third direction upward, the cover plate extends into the receiving cavity by a distance of H mm, where 0.25 ≤ (D×G) / (H×L1) ≤ 186.

7.

4. The battery according to claim 1, characterized in that, Along the third direction upwards, the maximum distance between the surface of the weld mark furthest from the cover plate and the cover plate is R mm, where 0.05 ≤ R / L1 ≤ 30.

5. The battery according to claim 1, characterized in that, At the short side of the preset surface, along the first direction, the maximum distance between the surface where the solder mark is furthest from the housing and the housing is T mm, where 0 ≤ T ≤ 0.

15.

6. The battery according to claim 1, characterized in that, The lowest point of the solder mark on the third direction is misaligned with the preset gap.

7. The battery according to claim 1, characterized in that, At the short side of the preset surface, the maximum cross-sectional area of ​​the solder mark along the first direction is S mm. 2 Where 0.6≤S≤1.

7.

8. The battery according to any one of claims 1-7, characterized in that, Both the cover plate and the housing are made of aluminum, wherein 1.8≤(D×G) / L1≤260.

9. The battery according to any one of claims 1-7, characterized in that, Both the cover plate and the shell are made of steel, wherein 0.9≤(D×G) / L1≤240.

10. The battery according to any one of claims 1-7, characterized in that, The minimum distance between the outer wall of the cover plate extending into the cavity and the inner wall of the cavity is L2mm, where L1-L2≤0.

05.

11. The battery according to claim 1, characterized in that, 0.3≤D≤1.4, and / or, 0.5≤G≤2, and / or, 0.01≤L1≤0.

2.

12. The battery according to claim 1, characterized in that, The ratio of the short side length to the long side length is greater than or equal to 0.1, wherein at the short side of the preset surface, (D×G) / L1≥10.

13. The battery according to claim 1, characterized in that, The solder mark has a cavity, and along the third direction, the orthographic projection of the cavity at least partially falls within the preset gap. The maximum size of the cavity is K mm, where 0.15 ≤ K / L1 ≤ 30.

14. The battery according to claim 13, characterized in that, Along the third direction, the minimum distance between the lowest point of the solder mark on the third direction and the cavity is ≥0.01mm.

15. The battery according to claim 13, characterized in that, Along the third direction, the minimum distance between the lowest point of the solder mark on the third direction and the cavity is between 0.01mm and 0.5mm, where K ≤ 0.

4.

16. The battery according to claim 13, characterized in that, 5≤(D×G) / L1≤230.

17. The battery according to claim 1, characterized in that, The solder mark has a cavity, and along the third direction, the orthographic projection of the cavity is offset from the preset gap, wherein 0.9≤(D×G) / L1≤240.

18. A battery pack, characterized in that, It includes at least two batteries as described in any one of claims 1-18, wherein the at least two batteries are arranged along the second direction.

19. The battery pack according to claim 18, characterized in that, A plurality of the batteries arranged along the second direction constitute a battery pack, wherein the ratio of the size of the battery pack along the second direction to the size of the battery pack along the first direction is greater than or equal to 5, wherein at the short side of the preset surface, (D×G)≥0.

3.

20. An electrical appliance, characterized in that, Includes the battery pack as described in claim 19.

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