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 inside the casing. The casing has a first surface. A weld mark is formed at the welded connection between the cover plate and the casing. The weld mark has a first cross-section parallel to a third direction, and a first reference line is on the first cross-section. Along the first direction, the total length of the pores located on the first reference line is L1 mm, the length of the first reference line on the weld mark is L mm, the dimension of the cover plate along a second direction is a mm, and the dimension of the cover plate along the first direction is b mm, 0.0004≤(L1 / L)(a / b)≤0.336. Compared with related technologies, this disclosure avoids excessive accumulation of pores at the critical stress section of the weld mark, reduces stress concentration in the area where the pores are located on the short side of the battery, reduces the risk of low weld mark strength on the short side of the battery, which is prone to cracking and leakage, and also reduces the risk of the internal insulating film of the battery being burned through.

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, batteries typically include a casing and a cover plate, which are connected by welding, resulting in weld marks at the welding joint.

[0003] Commercial vehicles experience greater vibrations, which can lead to stress concentration at the short-side weld lines of the battery cover during actual use. This can cause cracks in the weld lines between the cover and the casing, resulting in failure of the internal and external seals of the battery. Consequently, this can trigger severe thermal runaway and compromise the battery's safety. 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, wherein a receiving cavity is formed within the housing, the housing has a first surface, the first surface having a long side extending along a first direction and a short side extending along a second direction, the first direction, the second direction and a third direction being perpendicular to each other, the receiving cavity forming an opening on the first surface, the cover plate being welded to the housing to close the opening, and a weld mark being formed at the welded connection between the cover plate and the housing; At the short side of the battery, the solder mark has a first cross section parallel to the third direction and perpendicular to the second direction. The solder mark has a first reference line on the first cross section. The first reference line is perpendicular to the penetration direction of the solder mark. The first reference line is located at 3 / 4 of the maximum dimension of the first cross section along the penetration direction of the solder mark. The first reference line extends along the first direction. The solder mark has pores, and at least a portion of the pores are located on the first reference line. Along the first direction, the total length of the pores located on the first reference line is L1mm, the length of the first reference line on the solder mark is Lmm, at the short side of the battery, the dimension of the cover plate along the second direction is amm, and the dimension of the cover plate along the first direction is bmm, where 0.0004≤(L1 / L) (a / b) ≤ 0.336.

[0006] Secondly, this disclosure provides a battery pack including the aforementioned battery.

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

[0008] Compared with related technologies, this disclosure satisfies the following relationship by limiting the total length L1 of the pores located on the first reference line, the length L of the first reference line on the solder mark, the short side dimension a of the cover plate, and the long side dimension b of the cover plate: 0.0004 ≤ (L1 / L). (a / b) ≤ 0.336. This avoids excessive concentration of pores in the critical stress section of the solder joint, reduces stress concentration in the pore area on the short side of the battery under vibration or impact conditions, reduces the risk of low solder joint strength on the short side of the battery, which is prone to cracking and leakage, and at the same time reduces the risk of increased welding heat input, causing overheating in the welding area and burning through the internal insulating film 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 the AA direction.

[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. First surface; 51. Long side; 52. Short side; 6. First gap; 7. Weld mark; 8. Pore; A1, First section; X1, First Reference Line; 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] Research has found that existing battery packs mostly use a stacking method where large battery faces face each other to suppress deformation of the long side of the battery cover. However, due to the lack of effective constraint on the short side of the cover, the weld lines at the short side are prone to stress concentration and failure due to repeated tearing. Furthermore, many pores are formed inside the weld lines, especially at 3 / 4 of the weld depth, where the pore density is higher. At this location, pores from the bottom tend to accumulate, while pores from the top can be expelled during the welding process, resulting in the highest pore density at the bottom.

[0018] In actual battery use, the short side of the solder joint experiences the greatest vibration. During vibration, the solder joint often breaks at this point, leading to solder joint failure. The larger the ratio of the short side to the long side, the more pronounced the solder joint cracking problem becomes. Therefore, this application comprehensively controls the porosity ratio at 3 / 4 of the molten depth and the ratio of the short side to the long side of the cover plate to ensure the structural strength of the solder joint, prevent solder joint failure, and avoid severe thermal runaway inside the battery, which could cause the cover plate to fly off, increase the thermal runaway valve area, and affect the thermal safety of adjacent batteries. At the same time, it ensures the welding yield during the welding process, avoids overly stringent welding procedures, and does not require overly strict control of the welding speed during the welding process. Pre-welding drying of the welding area reduces welding time and avoids the problem of insulation film burn-through.

[0019] Reference Figures 1 to 6 As shown, this disclosure provides a battery, including a housing 1 and a cover plate 2 that covers the housing 1. The housing 1 and the cover plate 2 together constitute the outer casing of the battery.

[0020] The housing 1 is a component used to provide a receiving space to house the electrode assembly and other components and isolate them from the outside environment. The housing 1 generally includes a body with an opening at at least one end and a receiving cavity 3. The opening of the housing 1 can be closed by a cover plate 2 to seal and isolate the internal environment of the battery cell from the external environment. The materials of the housing include, but are not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, aluminum-plastic film, etc.

[0021] The cover plate 2 is a component that closes the opening of the housing 1 to isolate the internal environment of the battery cell from the external environment; the material of the cover plate 2 includes, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, aluminum-plastic film, etc.

[0022] In one feasible implementation, the battery casing is a cuboid structure. To better illustrate the battery structure, 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.

[0023] 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 first surface 5, which is parallel to the large surface of the cover plate 2. The first surface 5 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 first 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 touching. The receiving cavity 3 forms an opening 4 on the first surface 5. The opening 4 is a through area of ​​the receiving cavity 3 on the first 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.

[0024] A battery cell is the basic unit of a battery, typically consisting of a positive electrode, a negative electrode, and a separator. Lithium-ion cells primarily function by the movement of lithium ions between the positive and negative electrodes. In cylindrical cells, the three-layer thin-film structure is wound into a cylindrical electrode assembly, while in cuboid cells, the thin-film structure is wound or stacked into an electrode assembly with a roughly cuboid shape.

[0025] Electrolytes are liquid electrolytes that transport active ions. They are liquid materials that conduct ions while isolating electrons; electrolytes are composed of chemical substances such as solvents, electrolyte salts, and additives; solvents can be carbonates, carboxylic acid esters, or ethers; electrolyte salts can be lithium salts, sodium salts, or zinc salts; additives can be vinylene carbonate, fluoroethylene carbonate, propylene sulfite, vinyl sulfite, etc.

[0026] 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 first gap between the cover plate 2 extending into the receiving cavity 3 and the shell 1. The cover plate 2 and the shell 1 are welded together to close the opening 4. The welding method can be ultrasonic welding, laser welding, or resistance welding, preferably laser welding, to achieve isolation between the inside and outside of the battery, connect the cover plate 2 and the shell 1 into an integral structure, and close the first gap 6 between the cover plate 2 and the shell 1. The welding method can be top welding or side welding. Top welding can avoid the risk of excessive weld marks 7 on the side wall of the shell 1, which could lead to weld penetration or breakage of the side wall of the shell 1. The thickness of the cover plate 2 is generally greater than the thickness of the shell 1. Top welding better ensures the welding strength of the weld line and improves the welding rate. In the top welding method, the penetration direction of the weld mark 7 is parallel to the third direction D3, and the penetration direction of the weld mark 7 is parallel to the large surface of the cover plate 2. The penetration direction of the weld mark 7 can also be parallel to the large surface of the cover plate 2, forming a side weld. In this case, the penetration direction of the weld mark 7 is parallel to the third direction D3, which avoids the weld mark 7 formed by the top welding from cracking due to the vibration direction being parallel to the penetration direction during battery vibration.

[0027] The thickness of the cover plate 2 is greater than the thickness of the shell 1, which ensures the structural strength of the short side of the cover plate 2, improves the welding firmness, and at the same time avoids the shell 1 being too thick, resulting in low utilization of the internal space of the shell 1. In one feasible embodiment, the thickness of the cover plate 2 is between 1mm and 3mm, and the thickness of the shell 1 is between 1mm and 2.5mm.

[0028] A weld mark 7 is formed at the welded joint between the cover plate 2 and the shell 1. 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, forming a molten pool. The molten pool fills the first gap 6 between the cover plate 2 and the shell 1 and then solidifies to form the weld mark 7. The weld mark 7 connects the cover plate 2 and the shell 1 into a single unit, dispersing the stress generated by the battery under vibration or impact conditions. The dimension of the weld mark 7 in the weld depth direction is between 0.3mm and 1.4mm, and the dimension of the weld width direction is between 0.5mm and 2mm.

[0029] At the short side 52 of the battery, the solder mark 7 has a first cross-section A1 along a direction parallel to the third direction D3. The first cross-section A1 is the cross-sectional structure obtained by cutting the solder mark 7 along a direction parallel to the third direction D3. The first cross-section A1 has a first reference line X1, which is a baseline artificially set on the first cross-section A1. The first reference line X1 is perpendicular to the penetration direction and is located at 3 / 4 of the maximum penetration of the first cross-section A1. This position is a region rich in pores 8, and the pores 8 at this position affect the structural strength of the solder line. It is the force transmission path that has the greatest impact on the structural strength of the solder mark 7. The first reference line X1 extends along the first direction D1, and the extension direction of the first reference line X1 is consistent with the penetration direction of the solder mark 7.

[0030] The weld mark 7 contains pores 8, which are formed when the welding process is too fast or when aluminum alloy is welded, and the internal gas fails to escape in time. These pores are either discretely distributed or densely distributed in strips. The pores 8 reduce the effective load-bearing area of ​​the weld mark 7. At least some of the pores 8 are located on the first reference line X1, which makes it easy to cause stress concentration in the area of ​​the first reference line X1, resulting in a decrease in the structural strength of the weld mark 7.

[0031] In the embodiments provided in this disclosure, the total length of the pores 8 located on the first reference line X1 along the first direction D1 is defined as L1 mm. L1 is the sum of the lengths of all pores 8 passing through the first reference line X1 along the first direction D1. The larger L1 is, the larger the space occupied by the pores 8, and the more significant the impact on the structural strength of the solder mark 7. The value is defined as 0.01 ≤ L1 ≤ 0.7. The value can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7. Specifically, the value can be one of the aforementioned values, or any value between 0.01 and 0.7.

[0032] The length of the first reference line X1 on the solder mark 7 is L, where L is the length of the solder mark 7 on the first reference line X1. Within a certain range, the larger L is, the higher the structural strength of the solder mark 7. The constraint is 0.2 ≤ L ≤ 1.2. The value can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, or 1.2. The value can be one of the values ​​listed above, or any value between 0.2 and 1.2.

[0033] The method for measuring the total length of the pore 8 is as follows: using a metallographic microscope or a measuring microscope, the first section A1 obtained by cutting the battery solder area 7 along the third direction D3 and perpendicular to the second direction D2 is measured. At the same time, the pore 8 on the first reference line X1 specified above is measured. The pore 8 may be inclined relative to the first reference line X1, or its length or width direction may be parallel to the first reference line X1. The total length L1mm is the size of the part of the pore 8 that coincides with the first reference line X1.

[0034] At the short side 52 of the battery, the cover plate 2 has a dimension of a mm along the second direction D2, which is limited to 10 ≤ a ≤ 100. The value can be 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100. The value can be one of the values ​​listed above, or any value between 10 and 100.

[0035] The dimension of the cover plate 2 along the first direction D1 is b mm, which is limited to 100≤b≤400. The value can be 100, 150, 200, 250, 300, 350 or 400. The value can be one of the values ​​listed above, or any value between 100 and 400.

[0036] The constraints are: 0.008 ≤ L1 / L ≤ 0.58, 0.05 ≤ a / b ≤ 0.58. The relation must satisfy: 0.0004 ≤ (L1 / L) (a / b) ≤ 0.336. The relationship can take values ​​of 0.0004, 0.001, 0.01, 0.05, 0.1, 0.15, 0.2, 0.28, 0.3, or 0.336. The values ​​can be the aforementioned values ​​or any value between 0.0004 and 0.336. By controlling the proportion of space occupied by pores 8 on the first reference line X1, it is possible to avoid excessive pores 8 leading to a decrease in the structural strength of the weldment 7, while also allowing for the existence of slight pore defects, thus balancing the difficulty of the welding process.

[0037] If the ratio of the relationship is too small, it imposes excessive requirements on the proportion and size of the pores 8. Tiny or small pores 8 have limited impact on the performance of the solder mark 7 and do not require excessive constraints. While a too-small ratio can maximize the integrity of the solder mark 7, it increases the requirements for the welding process, necessitating adjustments to the welding speed and pre-welding drying of the welding area. This can lead to excessively long welding times and the risk of the insulating film burning through. Alternatively, if the short side 52 of the battery is much smaller than the long side 51, an excessively small short side 52 will result in insufficient effective bearing area for the solder mark 7, lower structural strength, and a risk of cracking and seal failure.

[0038] If the ratio of the relationship is too large, the proportion of pores 8 will be too high, which will significantly weaken the effective bearing area of ​​the solder mark 7, leading to a decrease in the structural strength and tear resistance of the solder mark 7. Under vibration or impact conditions, the solder mark 7 is prone to cracking from the pores 8, damaging the battery's sealing performance and causing electrolyte leakage. Alternatively, if the short side 52 of the battery is much larger than the long side 51, it will occupy too much space when adjacent batteries are stacked, reducing the energy density of the battery pack.

[0039] In the embodiments provided in this disclosure, the maximum area of ​​the first cross-section A1 is S mm. 2 The maximum area S of the first cross-section A1 is the overall outline area of ​​the weld mark 7 on the first cross-section A1. This maximum area is located at the short side 52 of the first surface 5, and is limited to 0.5 ≤ S ≤ 2. The value can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2. The specific values ​​can be those listed above, or any value between 0.5 and 2. If the maximum 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 area is too large, the cross-sectional area of ​​the weld mark 7 is excessive, expanding the welding heat-affected zone, causing welding deformation of the shell 1 and cover plate 2, and reducing the structural strength of the shell 1 and cover plate 2.

[0040] The total area of ​​the pores 8 on the first section A1 is S1 mm. 2 The total area S1 of the pores 8 on the first cross-section A1 is the sum of the areas of all pores 8 within the first cross-section A1, limited to 0.005 ≤ S1 ≤ 0.3. The value can be 0.005, 0.001, 0.005, 0.1, 0.15, 0.2, 0.25, or 3. Specifically, it can be one of the values ​​listed above, or any value between 0.005 and 3. This avoids the total area of ​​the pores 8 being too large, which would reduce the structural strength of the weldment 7, while also allowing for the existence of minor pore defects, thus balancing the difficulty of the welding process.

[0041] Where 0.01 ≤ S1 / S ≤ 0.15. The value can be 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 one of the values ​​listed above, or any value between 0.01 and 0.15. This avoids excessive reduction in the overall structural strength of the weldment 7 due to an excessively large proportion of the total area of ​​the pores 8, and also reduces the requirements for the welding process.

[0042] If this ratio is too small, it will impose excessive requirements on the volume ratio of pores 8. Tiny pores 8 have a limited impact on the performance of solder mark 7 and do 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 of the welding process and increase production costs.

[0043] If this ratio is too large, the volume of the pores 8 will be too large, which will significantly weaken the effective bearing area of ​​the solder mark 7, resulting in a decrease in the structural strength and tear resistance of the solder mark 7. Under vibration or impact conditions, the solder mark 7 is prone to cracking from the pores 8, damaging the battery sealing performance and causing electrolyte leakage.

[0044] At least a portion of the cover plate 2 extends into the receiving cavity 3 through the opening 4. A first gap 6 exists between the outer wall of the cover plate 2 extending into the receiving cavity 3 and the inner wall of the receiving cavity 3. The first gap 6 is annular or strip-shaped. During welding, the molten pool fills this first gap 6 to connect the shell 1 and the cover plate 2 into a single unit. Under vibration or impact conditions, stress concentration easily occurs at the first gap 6 in the weld mark 7, leading to damage and cracking of the weld mark 7.

[0045] In one feasible implementation, at least some of the pores 8 are located on the first gap 6 at the short side 52 of the first surface 5. As a weak structure within the solder mark 7, the pores 8 reduce the effective bearing area of ​​the solder mark 7 at the first gap 6, exacerbating the stress concentration of the solder mark 7 at the short side 52. Under vibration or impact conditions, cracks are more likely to occur at the pores 8, and the cracks will extend along the direction of the first gap 6, thereby causing the solder mark 7 to be damaged and cracked.

[0046] Therefore, the constraint relationship satisfies: 0.05 ≤ L1 / L ≤ 0.4. The value can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4, specifically the values ​​listed above, or any value between 0.05 and 0.4. By reducing the proportion of the total length of the pores 8, the overall structural strength of the solder joint 7 is enhanced to a certain extent, reducing the negative impact of the pores 8 at the first gap 6 on the performance of the solder joint 7.

[0047] In another feasible implementation, the pores 8 are misaligned within the first gap 6. The pores 8 within the weld 7 are not distributed within the area of ​​the first gap 6, but rather offset from it, thereby reducing stress concentration at the first gap 6 and allowing the weld 7 at the first gap 6 to retain its complete effective load-bearing area. Therefore, the constraint expression satisfies: 0.1 ≤ L1 / L ≤ 0.58. The value can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, or 0.58. The value can specifically be one of the aforementioned values, or any value between 0.1 and 0.58. This allows for more pores 8 within the weld 7, thereby reducing welding process difficulty and production costs, and improving production feasibility.

[0048] In the embodiments provided in this disclosure, at the short side 52 of the first surface 5, along the direction D1 parallel to the first direction, the minimum spacing of the first gap 6 is N mm. A suitable N dimension can provide sufficient filling space for the molten pool, ensuring that the molten pool can completely fill the first gap 6 and avoiding defects such as incomplete welding and lack of fusion. Preferably, this minimum spacing occurs at the short side 52 of the first surface 5, and is limited to 0.01 ≤ N ≤ 0.2. The value can be 0.01, 0.05, 0.1, 0.15, or 0.2, specifically 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 first gap 6. Beyond the preset value range, the molten pool is insufficiently filled, and the welding quality deteriorates.

[0049] If the value of the relationship is too small, the first gap 6 will be too small, the heat-affected zone during welding will expand, and welding deformation of the shell 1 and the cover plate 2 will occur. If the value of the relationship is too large, the first gap 6 will be too large, the molten pool will not be able to fully fill the first gap 6, and the weld connection strength will be insufficient.

[0050] In the embodiments provided in this disclosure, at the short side 52 of the battery, along the melting depth direction of the solder mark 7, the maximum distance between the first reference line X1 and the edge of the solder mark 7 is between 0.175mm and 0.35mm. The value can be 0.175mm, 0.2mm, 0.225mm, 0.25mm, 0.275mm, 0.3mm, 0.325mm, or 0.35mm; specifically, it can be one of the values ​​listed above, or any value between 0.175mm and 0.35mm. The maximum distance between the first reference line X1 and the edge of the weld mark 7 is the maximum distance from the first reference line X1 on the first section A1 to any edge of the weld mark 7. If this distance is too small, the effective load-bearing area of ​​the weld mark 7 will be too small, and it will be unable to effectively transfer and disperse the tearing stress caused by vibration or impact, resulting in stress concentration at the weld mark 7 and increasing the risk of cracking. If this distance is too large, the area of ​​the weld mark 7 will be excessive, the welding heat input will increase, the heat-affected zone will expand, and it will easily cause thermal deformation of the shell 1 and the cover plate 2, reducing the structural strength of the shell 1 and the cover plate 2.

[0051] In one feasible implementation, at the short side 52 of the battery, along the first direction D1, the minimum distance between two adjacent vents 8 is at least greater than 0.175 mm. This minimum distance is the shortest distance between the edges of any two adjacent vents 8. If this distance is too small, multiple vents 8 will aggregate to form a weak area, significantly reducing the effective load-bearing area of ​​the solder 7 in this area, exacerbating local stress concentration in the solder 7, and making the solder 7 prone to damage and cracking. By limiting the minimum distance to at least a set value, the vents 8 can be evenly distributed along the first direction D1, avoiding excessively dense aggregation of vents 8, ensuring the continuity of the solid area within the solder 7, and ensuring that the solder 7 between any two vents 8 has the load-bearing capacity to meet the preset requirements, reducing the risk of solder 7 cracking and failure.

[0052] In one feasible implementation, at the short side 52 of the battery, along the first direction D1, the minimum distance from the pore 8 to the outer edge of the solder mark 7 is D mm, where D is the shortest distance from the edge of any pore 8 inside the solder mark 7 to both edges of the solder mark 7 along the first direction D1, and is limited to 0.2 ≤ D ≤ 1. The value can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, specifically the values ​​listed above, or any value between 0.2 and 1. This avoids the pore 8 being too close to the edge of the solder mark 7, ensuring the structural strength of the edge area of ​​the solder mark 7, while also preventing multiple pores 8 from being excessively concentrated in the middle of the solder mark 7, reducing local stress concentration in the solder mark 7.

[0053] The structural strength of the edge region of the solder mark 7 is weaker than that of the central region. If the pores 8 are too close to the edge of the solder mark 7, stress concentration can easily occur in the edge region. Under vibration or impact conditions, cracks are prone to form in the edge region of the solder mark 7, leading to solder mark 7 breakage and seal failure. Therefore, in the embodiments provided in this disclosure, the minimum distance between the pores 8 and the edge of the solder mark 7 along the weld depth direction is defined as greater than or equal to 0.01 mm. This ensures sufficient solidity between the pores 8 and the edge of the solder mark 7, prevents the pores 8 from being too close to the edge of the solder mark 7, protects the structural integrity and stability of the solder mark 7, effectively disperses stress, and reduces the risk of fatigue cracking.

[0054] Furthermore, along the penetration direction of the weld 7, within a range of 0.01mm-0.5mm from the edge of the weld 7, the diameter of the pores 8 is less than or equal to 0.4mm. The edge region of the weld 7 is a weak area. Controlling the size of the pores 8 in this region can reduce the weakening effect of the pores 8 on the structural strength of the bottom region of the weld 7, increase the effective load-bearing area of ​​the edge region of the weld 7, reduce stress concentration, and ensure the structural stability of the weld 7.

[0055] In one feasible implementation, at the short side 52 of the battery, the size of the pore 8 along the weld depth direction of the weld mark 7 is larger than the size of the pore 8 along the weld width direction of the weld mark 7. Under vibration or impact conditions, the stress of the weld mark 7 at the short side 52 is mainly transmitted along the weld depth direction, which can ensure that sufficient continuous metal solid is retained inside the weld mark 7 in the weld width direction, ensuring that the weld mark 7 can effectively transmit the force, disperse the stress distribution, reduce stress concentration, and reduce the risk of cracking of the weld mark 7 at the short side 52 due to weakening by the pore 8.

[0056] The shape of the pore 8 can be one or more of the following: circular, elliptical, or racetrack-shaped. The outline of the circular, elliptical, and racetrack-shaped pore 8 is relatively smooth, which can reduce stress concentration, avoid local stress concentration at sharp edges and corners, reduce the risk of crack formation, and further improve the structural stability of the solder mark 7.

[0057] In the embodiments provided in this disclosure, along the penetration direction of the solder joint 7, the spacing of at least some pores 8 in the region below the first reference line X1 is greater than the spacing between at least some pores 8 in the region above the first reference line X1. The region above the first reference line X1 is close to the top of the solder joint 7, where pores 8 are more likely to escape during the welding process, resulting in a relatively low density of pores 8. The region below the first reference line X1 is close to the bottom edge of the solder joint 7, which is a weak area of ​​the solder joint 7. By adjusting the welding speed during the welding process and performing a drying process on the welding area before welding, the degree of pore aggregation in the weak area below can be reduced, the spacing of the pores 8 can be increased, and the overall size of the pores 8 can be reduced, thus preventing cracking of the bottom weld line.

[0058] In one feasible implementation, the welding between the shell 1 and the cover plate 2 adopts the top welding method. The weld depth direction of the weld mark 7 is perpendicular to the first surface 5. The weld mark 7 mainly bears the longitudinal stress perpendicular to the first surface 5. At the same time, the stress of the weld mark 7 at the short side 52 under vibration or impact conditions will be transmitted along the weld depth direction, resulting in a higher stress concentration of the weld mark 7 than other welding methods.

[0059] Therefore, the constraint expression satisfies: 0.0004 ≤ (L1 / L) (a / b) ≤ 0.28. The value can be 0.0004, 0.001, 0.01, 0.05, 0.1, 0.15, 0.2, or 0.28. The value can be one of the values ​​listed above, or any value between 0.00015 and 0.28. This reduces the proportion of porosity 8, increases the effective load-bearing area of ​​the weld 7 to a certain extent, avoids excessive stress concentration, and reduces the risk of weld 7 cracking and failure.

[0060] In another feasible implementation, the welding between the shell 1 and the cover plate 2 adopts a side welding method, and the penetration direction of the weld mark 7 is perpendicular to the third direction D3. This avoids the weld mark 7 formed by the top welding from cracking due to the vibration direction being parallel to the penetration direction during battery vibration.

[0061] In the embodiments provided in this disclosure, at the short side 52 of the battery, the ratio of the maximum weld width to the maximum weld depth of the solder mark 7 is less than or equal to 2.7. While ensuring that the solder mark 7 has a certain lateral stress-bearing area, it ensures that the solder mark 7 has sufficient thickness to bear the stress, avoiding a decrease in structural strength and stability due to the solder mark 7 being too thin.

[0062] In one feasible implementation, along the penetration direction of the weld mark 7, the weld mark 7 includes a first welding area and a second welding area. The first welding area is located above the second welding area, and the second welding area is closer to the bottom of the weld mark 7 than the first welding area. The ratio of the maximum weld width of the first welding area to the maximum weld width of the second welding area is greater than or equal to 1.6 mm. The weld mark 7 can be shaped like an inverted triangle. The first welding area has a wider lateral dimension, which can more effectively disperse the stress at the short side 52, avoiding excessive stress concentration in the lower second welding area, thereby reducing the risk of bottom cracking failure of the weld mark 7 and ensuring the overall structural stability of the weld mark 7. At the same time, by reducing the size of the second welding area, the impact of welding heat on the surrounding metal structure of the weld mark 7 can be reduced.

[0063] In the embodiments provided in this disclosure, along the penetration direction of the solder mark 7, the area of ​​all pores 8 located on one side of the first reference line X1 is S3mm. 2 S3 is the total area of ​​all vents 8 located on one side of the first reference line X1 (as shown above) along the third direction D3, and the area of ​​all vents 8 located on the other side of the first reference line X1 is S4mm. 2 S4 is the total area of ​​all pores 8 located on the other side of the first reference line X1 (as shown below). If the area of ​​pores 8 on one side is too large and the area of ​​pores 8 on the other side is too small, it will result in an excessive difference in the effective bearing area on both sides of the solder mark 7. The effective bearing area of ​​the solder mark 7 on the side with too much pore area will be too small, which will weaken the structural strength of the solder mark 7 in this area and thus cause cracking in the area of ​​the solder mark 7 on one side.

[0064] Therefore, the relationship is defined as: 0.01 ≤ S3 / S4 ≤ 0.3. The value can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3. Specifically, it can be one of the values ​​listed above, or any value between 0.01 and 0.3. By limiting this ratio within a preset range, the area distribution of the pores 8 on both sides of the first reference line X1 is made relatively uniform, preventing excessive aggregation of the pores 8 to one side on the third direction D3. This ensures that the solder joint areas 7 on both sides of the first reference line X1 have balanced structural strength, enabling them to collaboratively transfer stress and reducing the risk of damage and cracking of the solder joint 7.

[0065] In the embodiments provided in this disclosure, at the short side 52 of the first surface 5, along the third direction D3, the maximum distance between the edge of the solder mark 7 located outside the battery and the cover plate 2 is R mm. Preferably, this maximum distance is located at the short side 52 of the first surface 5, and is defined as 0.01 ≤ R ≤ 0.3. The value can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 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 at 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.

[0066] In the embodiments provided in this disclosure, the maximum distance between the edge of the solder mark 7 and the shell 1 along the first direction D1 is T mm, which is limited to 0 ≤ T ≤ 0.15. The value can be 0, 0.01, 0.03, 0.05, 0.07, 0.1, 0.13, 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 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 at the short side 52 of the solder mark 7, which is prone to cracking. If T is too large, the solder mark 7 is too thick, which will affect the coating of the blue film on the battery surface, resulting in insufficient adhesion of the blue film, making the blue film easy to fall off. At the same time, the welding time is too long, resulting in excessive continuous input of welding heat, causing deformation of the shell 1, and increasing the failure risk of the solder mark 7 at the short side 52.

[0067] The blue film is applied to the outer surface of the battery's metal casing to improve the insulation performance of the battery's outer surface. It can be applied to the outer surface of the casing by adhesive or coating. The blue film is composed of polyester film (PET, Polyethylene Terephthalate), polyimide (PI), polypropylene (PP), or polyethylene (PE).

[0068] 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.

[0069] 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.

[0070] 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).

[0071] (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).

[0072] (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.

[0073] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0074] (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.

[0075] 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.

[0076] 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.

[0077] The solvent can be deionized water, NMP (N-methylpyrrolidone), alcohol, ether, ketone or other types of pyrrolidone, etc.

[0078] 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.).

[0079] 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.).

[0080] 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.

[0081] 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 will be prepared, 50 batteries will be grouped together, and they will be arranged along the width direction of the batteries to form a battery column. The battery columns will be arranged along the length direction of the batteries to form a battery pack. The values ​​of L1, L, a and b for each embodiment and comparative example are shown in Table 2. Other test conditions are kept consistent.

[0082] 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.

[0083] Table 1: After the vibration ends, observe the junction between the short side 52 of the battery cover 2 and the battery casing 1 to see if any leakage occurs. The leakage rate is calculated as (number of batteries that leaked / 100). 100%.

[0084] If the battery leakage rate is less than or equal to 1%, the test result is considered good; if the battery leakage rate is greater than 1% but less than 3%, the test result is considered qualified; if the battery leakage rate is greater than 3%, it is considered unqualified.

[0085] 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 inside the casing 1, and the cover plate 2 was welded to the casing 1 using laser welding technology. During the welding process, the welding power was maintained at 2000W, and the welding speed was set to 50mm / s. After the welding operation was completed, the battery was disassembled to check whether the insulating film had been penetrated by the weld. If the insulating film was penetrated by the weld, the structure was unqualified; otherwise, the result was qualified.

[0086] The following is an example from Table 2: Table 2: Based on the test results in Table 2 above, and in conjunction with Examples 1-15, when (L1 / L) The formula value of (a / b) satisfies 0.0004 ≤ (L1 / L) When (a / b) ≤ 0.336, the length of the pores 8 of the weld mark 7 is compatible with the assembly gap of the cover plate 2. After testing, the weld structure of the short side 52 of the battery is stable under vibration conditions, and there is no cracking that would lead to battery leakage. After disassembling the battery, no weld penetration was found in the insulating film.

[0087] In Comparative Example 1 (L1 / L) If the formula value of (a / b) is less than 0.0004, it will lead to excessive welding time, causing the insulating film to burn through. The structural strength of weld mark 7 is low, posing a risk of cracking and sealing failure. In Comparative Example 2, (L1 / L) The formula value of (a / b) is greater than 0.336. Under vibration or impact conditions, the solder mark 7 is prone to cracking from the pore 8, which damages the battery sealing performance, causes electrolyte leakage, occupies too much space when adjacent batteries are stacked, and reduces the energy density of the battery pack.

[0088] 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, resulting in weaker constraints on the short side 52 of the first 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.

[0089] The battery provided in this application ensures the structural strength of the weld mark 7 by comprehensively controlling the proportion of pores 8 in the 3 / 4 melt depth and the ratio of the size of the short side 52 to the size of the long side 51 of the battery. This prevents the weld mark 7 from failing, causing severe thermal runaway inside the battery, which would result in the cover plate 2 flying out, increasing the thermal runaway valve opening area, and affecting the thermal safety of adjacent batteries. At the same time, it ensures the welding yield during the welding process and avoids the welding process being too harsh.

[0090] Furthermore, multiple batteries arranged along the second direction D2 form a battery pack. The ratio of the size of the battery pack along the second direction D2 to the size of the battery pack 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 larger. The value can be specifically the values ​​listed above, or any value greater than 5.

[0091] Thirdly, this disclosure provides an electrical device that may include the aforementioned battery pack.

[0092] 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.

[0093] In addition, electrical equipment can also be used for the storage, conversion, and release of recyclable electrical energy.

[0094] 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 first 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 first surface. 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. At the short side of the battery, the solder mark has a first cross section parallel to the third direction and perpendicular to the second direction. The solder mark has a first reference line on the first cross section. The first reference line is perpendicular to the penetration direction of the solder mark. The first reference line is located at 3 / 4 of the maximum dimension of the first cross section along the penetration direction of the solder mark. The first reference line extends along the first direction. The solder mark has pores, and at least a portion of the pores are located on the first reference line. Along the first direction, the total length of the pores located on the first reference line is L1mm, the length of the first reference line on the solder mark is Lmm, at the short side of the battery, the dimension of the cover plate along the second direction is amm, and the dimension of the cover plate along the first direction is bmm, where 0.0004≤(L1 / L) (a / b) ≤ 0.

336.

2. The battery according to claim 1, characterized in that, The maximum area of ​​the first cross section is S mm 2 The total area of ​​the pores on the first cross section is S1mm. 2 Where 0.01≤S1 / S≤0.

15.

3. The battery according to claim 1, characterized in that, At least a portion of the cover plate extends into the receiving cavity through the opening, and a first gap exists between the outer wall surface of the cover plate extending into the receiving cavity and the inner wall surface of the receiving cavity, and at least a portion of the air holes are located in the first gap, wherein 0.05≤L1 / L≤0.

4.

4. The battery according to claim 1, characterized in that, At least a portion of the cover plate extends into the receiving cavity through the opening, and a first gap exists between the outer wall surface of the cover plate extending into the receiving cavity and the inner wall surface of the receiving cavity, wherein the vent is located in the first gap, and 0.1≤L1 / L≤0.

58.

5. The battery according to claim 3 or 4, characterized in that, At the short side of the battery, along the direction parallel to the first direction, the minimum spacing of the first gap is N mm, where 0.01 ≤ N ≤ 0.

2.

6. The battery according to claim 1, characterized in that, Along the direction of the weld penetration, the maximum distance between the first reference line and the edge of the weld is between 0.175mm and 0.35mm.

7. The battery according to claim 1, characterized in that, At the short side of the battery, along the first direction, the minimum spacing between two adjacent air holes is at least greater than 0.175 mm.

8. The battery according to claim 1, characterized in that, At the short side of the battery, along the first direction, the minimum distance from the pore to the outer edge of the solder mark is D mm, where 0.2 ≤ D ≤ 1.

9. The battery according to claim 1, characterized in that, Along the direction of the weld penetration, the minimum distance between the pore and the edge of the weld is greater than or equal to 0.01 mm.

10. The battery according to claim 1, characterized in that, Along the direction of the weld penetration, within a range of 0.01mm-0.5mm from the edge of the weld, the diameter of the pore is less than or equal to 0.4mm.

11. The battery according to any one of claims 1-10, characterized in that, At the short side of the battery, the size of the pore along the weld depth direction is larger than the size of the pore along the weld width direction.

12. The battery according to any one of claims 1-10, characterized in that, The shape of the pores is one or more of the following: circular, elliptical, or racetrack-shaped.

13. The battery according to any one of claims 1-10, characterized in that, Along the weld penetration direction, the spacing of at least some of the pores in the region below the first reference line is greater than the spacing between at least some of the pores in the region above the first reference line.

14. The battery according to any one of claims 1-10, characterized in that, The penetration direction of the solder mark is perpendicular to the first surface, and 0.0004 ≤ (L1 / L). (a / b) ≤ 0.

28.

15. The battery according to any one of claims 1-10, characterized in that, The direction of the weld penetration is perpendicular to the third direction.

16. The battery according to any one of claims 1-10, characterized in that, At the short side of the battery, the ratio of the maximum weld width to the maximum weld depth is less than or equal to 2.

7.

17. The battery according to any one of claims 1-10, characterized in that, Along the weld penetration direction, the weld includes a first welding zone and a second welding zone, wherein the ratio of the maximum weld width of the first welding zone to the maximum weld width of the second welding zone is greater than or equal to 1.6 mm.

18. The battery according to claim 1, characterized in that, Along the weld penetration direction, the area of ​​all pores located on one side of the first reference line is S3mm. 2 The area of ​​all pores located on the other side of the first reference line is S4mm. 2 Where 0.01≤S3 / S4≤0.

3.

19. The battery according to claim 1, characterized in that, At the short side of the first surface, along the third direction upwards, the maximum distance between the surface where the solder mark is furthest from the cover plate and the cover plate is R mm, where 0.01 ≤ R ≤ 0.

3.

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

15.

21. The battery according to claim 1, characterized in that, 0.01≤L1≤0.7, and / or, 0.05≤a / b≤0.58, and / or, 0.2≤L≤1.

2.

22. A battery pack, characterized in that, It includes at least two batteries as described in any one of claims 1-21, wherein the at least two batteries are arranged along the second direction.

23. An electrical appliance, characterized in that, Includes the battery pack as described in claim 22.

Images