Batteries and battery packs

Abstract

This disclosure provides a battery and a battery pack. The battery includes a casing, a cover plate, and a battery cell. At least one end of the casing has an opening. The inner surface of the casing includes a first inner surface and a second inner surface, and at least one of the first inner surfaces has a first protrusion. The battery cell is housed within a cavity. The outer surface of the battery cell includes a first outer surface and a second outer surface. The dimension of the first protrusion in a first direction is x. The mass content of silicon on the first inner surface is y%. The ratio of the area of ​​the second outer surface to the area of ​​the first outer surface is z. The battery capacity is A, and 110Ah / mm² ≤ A / (x×y×z) ≤ 349655Ah / mm². This disclosure provides a first protrusion protruding towards the battery cell on the large surface of the casing near the opening. The first protrusion itself acts as a reinforcing rib, significantly reducing the alternating tensile-shear stress level at the weld caused by the expansion of the large surface of the casing, thereby inhibiting the initiation and propagation of fatigue cracks.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of batteries, in particular to a battery and a battery pack. BACKGROUND

[0002] With the increasing demand for high-energy-density power batteries in new energy vehicles, energy storage systems and portable terminals, prismatic lithium-ion batteries have become one of the mainstream packaging forms of power batteries due to their high assembly efficiency, high space utilization rate and short heat dissipation path.

[0003] In related technologies, the shell of a prismatic lithium-ion battery is usually formed by stamping an aluminum alloy, and the structure includes two pairs of oppositely arranged large faces and two pairs of oppositely arranged small faces, wherein the area of the large face is larger than that of the small face. An opening is provided at one end or both ends of the shell, and a cover plate is welded and connected to the shell along the opening by laser penetration welding or composite welding to form a sealed accommodation cavity.

[0004] Due to the high risk of deformation of the large face of the battery shell, the connection between the large face of the battery shell and the cover plate fails, the inside and outside of the battery are connected, the internal electrolyte vapor contacts with the external air, which will instantly cause high-temperature liquid spraying, fire or explosion and other thermal runaway accidents, seriously threatening the safety of passengers and equipment. SUMMARY

[0005] The purpose of the present disclosure is to provide a battery and a battery pack to solve the technical problem that the weld between the long side of the cover plate and the large face of the shell is prone to fatigue cracking in related technologies.

[0006] In a first aspect, the present disclosure provides a battery comprising a shell, a cover plate and a cell;

[0007] At least one end of the shell is provided with an opening, the cover plate seals the opening and is welded and connected to the shell to form an accommodation cavity, the shell includes an inner surface close to the accommodation cavity and an outer surface away from the accommodation cavity, the inner surface includes two first inner surfaces spaced apart along a first direction and two second inner surfaces spaced apart along a second direction, and a third direction perpendicular to the cover plate, the first direction, the second direction and the third direction are perpendicular to each other, the area of the first inner surface is larger than that of the second inner surface, at least one first inner surface is provided with a first protruding portion, the first protruding portion is protrudingly arranged along the direction of the first inner surface towards the cell, and the first protruding portion is close to or continuous with the surface where the opening is located;

[0008] The electric core is accommodated in the accommodating cavity, and an outer surface of the electric core includes two first outer surfaces arranged at intervals in the first direction and a second outer surface formed with an electric core opening end, and an area of the first outer surface is greater than an area of the second outer surface.

[0009] In the formula, x is a size of the first protruding part in the first direction, and the unit of x is mm, y is a mass content of silicon elements at the first inner surface, z is a ratio of the area of the second outer surface of a single electric core to the area of the first outer surface of the electric core, and A is a capacity of the battery, and the unit of A is Ah, and 110 Ah / mm≤A / (x×y×z)≤349655 Ah / mm.

[0010] In a second aspect, the disclosure provides a battery pack, including the battery described above, and a plurality of the batteries are arranged side by side, and the wall body where the first inner surface of any battery is located is parallel to the wall body where the first inner surface of the adjacent battery is located.

[0011] Compared with the related art, the first protruding part protruding towards the electric core is arranged at a position close to the opening part of the shell large surface, the first protruding part itself can reduce the alternating tensile-shear composite stress level at the weld seam, thereby inhibiting the initiation and propagation of fatigue cracks, and the molten pool can form a larger penetration and a wider throat when the cover plate is welded with the shell, so as to simultaneously improve the structural rigidity and fatigue strength of the area where the weld seam is located without increasing the wall thickness of the shell. Meanwhile, the size x of the first protruding part in the first direction, the mass content y of silicon elements at the first inner surface, the ratio z of the area of the second outer surface to the area of the first outer surface, and the capacity A of the battery satisfy the quantitative relationship of 110 Ah / mm≤A / (x×y×z)≤349655 Ah / mm. The long side of the opening part of the shell is locally rigidly reinforced in the welding area to inhibit the alternating stress transmitted to the weld seam from the shell large surface swelling, and a buffer space matching the gas production is reserved on the side of the electric core to facilitate the discharge of gas from the inside of the electric core, reduce the swelling of the electric core, and further reduce the internal resistance of the electric core, and improve the fast charging and overcurrent capacity. Thus, the energy density, reliability and safety are simultaneously improved. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a perspective view of the shell of the battery provided by the disclosure.

[0013] Figure 2 is Figure 1 a front view of the shell provided.

[0014] Figure 3 is Figure 2 an A-A side view of the shell provided.

[0015] Figure 4 is Figure 3 An amplification structure provided by the present disclosure.

[0016] Figure 5 is a structure diagram of a battery provided by the present disclosure.

[0017] Figure 6 is Figure 5 A side view of a first protrusion with a first structure of a battery provided by the present disclosure.

[0018] Figure 7 is Figure 5 A top view of a first protrusion with a first structure of a battery provided by the present disclosure.

[0019] Figure 8 is Figure 5 A side view of a first protrusion with a second structure of a battery provided by the present disclosure.

[0020] Figure 9 is Figure 5 A side view of a first protrusion with a third structure of a battery provided by the present disclosure.

[0021] Figure 10 is Figure 5 A side view of a first protrusion with a fourth structure of a battery provided by the present disclosure.

[0022] Figure 11 is Figure 5 A side view of a first protrusion with a fifth structure of a battery provided by the present disclosure.

[0023] Figure 12 is Figure 5 A top view of a first protrusion with a sixth structure of a battery provided by the present disclosure.

[0024] Figure 13 is Figure 5 A top view of a first protrusion with a seventh structure of a battery provided by the present disclosure.

[0025] Figure 14 is Figure 5 A top view of a first protrusion with an eighth structure of a battery provided by the present disclosure.

[0026] Figure 15 is Figure 5 A top view of a protrusion structure with a first position of a battery provided by the present disclosure.

[0027] Figure 16 is Figure 5 A top view of a protrusion structure with a second position of a battery provided by the present disclosure.

[0028] Figure 17yes Figure 5 A top view of the provided battery having a second protrusion with the first structure.

[0029] Figure 18 yes Figure 5 A top view of the second protrusion of the provided battery having a second structure.

[0030] Figure 19 yes Figure 5 The provided battery features a side view showing the tab structure.

[0031] Figure 20 yes Figure 5 The provided battery is shown in a top view of the first position of the tab structure.

[0032] Figure 21 yes Figure 5 The provided battery is shown in a top view of the first position of the electrode structure and adapter.

[0033] Figure 22 yes Figure 5 A side view of the provided battery with a third protrusion.

[0034] Figure 23 yes Figure 5 A top view of the battery provided, showing the third protrusion of the first structure.

[0035] Figure 24 yes Figure 5 A top view of the battery provided, showing the third protrusion with the second structure.

[0036] Figure 25 yes Figure 5 The provided battery is shown in the side view of the first type of welded part.

[0037] Figure 26 yes Figure 5 The provided battery is shown in the side view of the second type of welded part.

[0038] Figure 27 yes Figure 5 A top view of one of the battery cells housed within the casing.

[0039] Figure 28 yes Figure 5 A top view of the two battery cells housed within the casing.

[0040] Figure 29 yes Figure 5 The provided battery is shown in a side view of the electrode structure in the second position.

[0041] Figure 30 yesFigure 5 The provided battery is shown in a side view of the second position of the tab structure and the adapter.

[0042] Figure 31 yes Figure 5 A schematic diagram of the structure of the cover plate with protrusions for the provided battery.

[0043] Figure 32 yes Figure 5 Side view of the cover plate of the first structure of the provided battery.

[0044] Figure 33 yes Figure 5 Side view of the cover plate of the second structure of the provided battery.

[0045] Figure 34 yes Figure 5 Side view of the cover plate of the third structure of the provided battery.

[0046] Figure 35 yes Figure 5 A schematic diagram showing the positional relationship between the battery terminals and the pressure relief components.

[0047] Figure 36 yes Figure 5 The provided battery is shown in a side view of the electrode structure in a third position.

[0048] Figure 37 This is a schematic diagram of the structure of the energy-absorbing component at the first position provided in the embodiments of this disclosure.

[0049] Figure 38 This is a schematic diagram of the structure of the energy-absorbing component at the second position provided in the embodiments of this disclosure.

[0050] Figure 39 This is a schematic diagram of the structure of the energy-absorbing component at the third position provided in the embodiments of this disclosure.

[0051] Figure 40 This is a schematic diagram of the structure of a heat exchange component at a first location provided in an embodiment of this disclosure.

[0052] Figure 41 This is a schematic diagram of the structure of the heat exchange component at the second location provided in the embodiments of this disclosure.

[0053] Figure 42 This is a schematic diagram of the structure of the battery pack used in the electrical equipment provided in the embodiments of this disclosure.

[0054] Explanation of reference numerals in the attached figures:

[0055] 10-Shell, 11-Opening, 12-Receiving cavity, 13-First inner surface, 14-Second inner surface, 15-First protrusion, 151-First segment, 152-Second segment, 153-First sub-protrusion, 16-First wall, 17-Protrusion, 18-Second protrusion, 181-Second sub-protrusion, 19-Third protrusion, 191-Third sub-protrusion;

[0056] 20-Cover plate, 21-Cover plate body, 22-Boss, 23-Through hole;

[0057] 30-Battery cell, 301-Horizontal extension section, 302-Arc-shaped connection section, 31-First outer surface, 32-Second outer surface, 33-Third outer surface, 34-Battery cell body, 35-Taper, 36-Adapter, 361-Vertical section, 362-Horizontal section;

[0058] 40 - Welding section;

[0059] 50-Pole Column;

[0060] 60 - Pressure relief component;

[0061] 70 - Energy Absorption Component;

[0062] 80 - Heat exchanger assembly;

[0063] 100-battery;

[0064] 200-battery pack;

[0065] D1 - First direction;

[0066] D2 - Second direction;

[0067] D3-Third direction. Detailed Implementation

[0068] 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.

[0069] like Figures 1 to 42 As shown, an embodiment of this disclosure provides a battery 100, including a casing 10, a cover plate 20, and a battery cell 30.

[0070] The shell 10 and the cover plate 20 can be made of one or more of the following materials: aluminum, aluminum alloy, martensitic steel, austenitic steel, nickel, copper, titanium, magnesium, etc.

[0071] Cell 30 is the component in battery 100 where electrochemical reactions occur; it is the smallest unit in battery 100 capable of electrochemical reactions such as charging / discharging. It typically includes a positive electrode, a negative electrode, and a separator. Lithium-ion cells primarily function by the intercalation and deintercalation 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.

[0072] At least one end of the shell 10 is provided with an opening 11. A cover plate 20 seals the opening 11 and is welded to the shell 10 to form a receiving cavity 12. In one feasible embodiment, the shell 10 is a quadrangular prism with one or both ends open (opening 11). After the cover plate 20 covers the opening 11, it is continuously welded circumferentially by laser welding to form an airtight receiving cavity 12. The weld between the cover plate 20 and the shell 10 forms a circumferentially closed weld, which becomes a high-stress area where fatigue cracks are most likely to initiate and propagate. Once the weld fatigue cracks, it will instantly trigger thermal runaway accidents such as high-temperature liquid spraying, fire, or even explosion.

[0073] The housing 10 includes an inner surface near the receiving cavity 12 and an outer surface away from the receiving cavity 12. The housing 10 has inner and outer surfaces along its wall thickness direction, with the inner surface facing the battery cell 30 and the outer surface facing the external components of the battery 100. The inner surface includes two first inner surfaces 13 spaced apart along a first direction D1 and two second inner surfaces 14 spaced apart along a second direction D2. It also includes a third direction D3 perpendicular to the cover plate 20. Both the first inner surfaces 13 and the second inner surfaces 14 extend along the third direction D3, which is perpendicular to the cover plate 20. The first direction D1, the second direction D2, and the third direction D3 are mutually perpendicular, and together they form a three-dimensional coordinate system. The battery 100 provided in this embodiment is a quadrangular prism battery 100. The first inner surfaces 13 arranged side-by-side along the first direction D1 are the large surfaces of the housing 10, and the second inner surfaces 14 arranged side-by-side along the second direction D2 are the small surfaces of the housing 10. The area of ​​the first inner surface 13 is larger than the area of ​​the second inner surface 14.

[0074] The study found that the failure of the weld connection between the opening 11 of the battery casing 10 and the cover plate 20, the breakage of the connection between the cover plate 20 and the casing 10, severe thermal runaway, and the easy detachment of the cover plate 20 from the casing 10 are mainly due to the preferential cracking of the weld lines on the large surface of the battery casing 10, as this area is more prone to deformation. During the charging and discharging process inside the battery 100, the stiffness of the large surface of the battery casing 10 is much lower than that of the cover plate 20 and the surrounding walls. When the internal gas production increases, the central area of ​​the large surface first undergoes bulging deformation, generating significant circumferential tensile stress. This causes the weld between the long side of the cover plate 20 and the large surface of the casing 10 to be under alternating tensile-shear combined stress for a long time, making this area extremely susceptible to fatigue cracks. The preferential cracking of this weld creates a connection between the inside and outside of the battery 100, causing the internal electrolyte vapor to come into contact with the external air, instantly triggering thermal runaway accidents such as high-temperature liquid spraying, fire, or even explosion, seriously threatening the safety of occupants and equipment.

[0075] By providing a first protrusion 15 on at least one first inner surface 13, and by forming an inwardly protruding reinforcing rib (first protrusion 15) on the large surface (first inner surface 13), local stiffness can be improved, the overall strength at the weld line can be increased, the bending stiffness of the large surface of the shell 10 can be improved and the deflection can be reduced, the alternating tensile-shear stress amplitude transmitted to the long side weld of the cover plate 20 can be reduced, and the fatigue life of the weld can be significantly improved.

[0076] The first protrusion 15 protrudes along the first inner surface 13 toward the cell 30. The protrusion direction of the first protrusion 15 is toward the cell 30, that is, it protrudes inward along the first direction D1. This avoids the first protrusion 15 encroaching on the battery 100 module space. The original gap between the surface of the cell 30 and the inner surface of the casing 10 is used to accommodate the first protrusion 15, thus ensuring the energy density and space utilization of the battery 100.

[0077] The first protrusion 15 is close to or continues on the surface where the opening 11 is located. The distance between the first protrusion 15 and the end face where the opening 11 of the housing 10 is located is ≤5mm, or it is directly connected to the end face where the opening 11 is located. This makes the root of the reinforcing rib as close as possible to the weld, preventing the large-area bulging deformation of the housing 10 from being transmitted to the weld.

[0078] The battery cell 30 is housed within the receiving cavity 12. The outer surface of the battery cell 30 includes two first outer surfaces 31 spaced apart along a first direction D1, and a second outer surface 32. The second outer surface 32 forms an open end of the battery cell. The end face of the open end is the open surface of the battery cell 30, which can be the surface from which the tab 35 is led out, or it can be the surface opposite to the surface from which the tab 35 is led out. The area of ​​the first outer surface 31 is larger than the area of ​​the second outer surface 32. The battery cell 30 has a flat wound or stacked structure. If the battery cell 30 has a wound structure, the first outer surface 31 does not include the bent section. The larger surface of the battery cell 30 (the first outer surface 31) is opposite to the larger surface of the housing 10 (the first inner surface 13). The first outer surface 31 also expands during circulation and gas generation. The first protrusion 15 can absorb the expansion of the battery cell 30 while suppressing the expansion of the housing 10.

[0079] Where: Reference Figure 6 As shown, the dimension of the first protrusion 15 in the first direction D1 is x, where x is the dimension of the first protrusion 15 protruding from the first inner surface 13. The unit of x is mm, and the value of x is in the range of 0.1-1.5 mm, preferably 0.1-0.5 mm. Within this range, the overall strength of the welding line between the large surface of the battery 100 casing 10 and the cover plate 20 is ensured, while avoiding the occupation of the buffer gap inside the battery 100, which would result in insufficient overall volumetric energy density of the battery 100.

[0080] The wall thickness of the wall on the first inner surface 13 is between 0.1mm and 2.5mm. The shell 10 can be made of steel or aluminum. The wall thickness of the steel shell 10 can be less than that of the aluminum shell 10.

[0081] The mass content of silicon in the 13 locations on the first inner surface is y%, where y ranges from 0.1 to 0.9. Silicon content, as a key alloying element in laser welding, directly determines the fluidity of the weld pool and the toughness of the heat-affected zone, and is a common controlling factor for weld fatigue life and shell formability. Increasing the silicon content can improve the fluidity of the laser weld pool and the width of the weld throat, but excessively high levels will reduce plasticity and fatigue performance. This range balances weld fatigue strength and crack resistance.

[0082] The ratio of the area of ​​the second outer surface 32 to the area of ​​the first outer surface 31 of a single battery cell 30 is z, and the units of the areas of the second outer surface 32 and the first outer surface 31 are both mm. 2 z is the ratio of the end face area of ​​the open end of the battery cell to the total surface area of ​​the battery cell (30mm²), with a value ranging from 0.01 to 0.6. The end face area of ​​the open end of a single battery cell ranges from 120 to 96000 mm². 2 The preferred range is 1000-20000mm. 2 The surface area of ​​a single battery cell ranges from 10,000 to 160,000 mm².2 The preferred range is 10000-80000mm 2 The smaller the z-value, the flatter the cell 30, and the larger the lateral gap between the casing 10 and the cell 30, which is used to accommodate the expansion and gas generation of the cell 30. However, if the cell 30 is too small, the gas inside the cell 30 cannot be discharged from the opening end of the cell in time, resulting in severe swelling of the large area of ​​the battery 100. If the z-value is too large, the overall energy density of the cell 30 is low, and the surface density and compaction density of the electrode are also low.

[0083] The capacity of battery 100 is A, and the unit of A is Ah. The value of A ranges from 80 to 700 Ah, preferably from 80 to 300 Ah. The value of A is proportional to the mass of active material and the total amount of gas produced. The larger the value of A, the higher the energy density, but the higher the risk of thermal runaway.

[0084] Among them, the dimension x of the first protrusion 15 in the first direction D1 is defined, the mass content y% of silicon element in the first inner surface 13 is defined, the ratio z of the area of ​​the second outer surface 32 to the area of ​​the first outer surface 31 is defined, and the capacity A of the battery 100 satisfies 110Ah / mm≤A / (x×y×z)≤349655Ah / mm. Specifically, the values ​​can be 110Ah / mm, 200Ah / mm, 250Ah / mm, 1000Ah / mm, 3000Ah / mm, 8000Ah / mm, 10000Ah / mm, 50000Ah / mm, 70000Ah / mm, 100000Ah / mm, 119050Ah / mm, 150000Ah / mm, 200000Ah / mm, 220000Ah / mm, 250000Ah / mm, 300000Ah / mm, 320000Ah / mm, or 349655Ah / mm. The values ​​can be the ones listed above or any value between 110Ah / mm and 349655Ah / mm. The preferred value of the formula A / (x×y×z) is 250Ah / mm-119050Ah / mm, and the most preferred range is 7500Ah / mm-55000Ah / mm.

[0085] When the formula value of A / (x×y×z) is within a preset range, the long side of the opening 11 of the casing 10 receives local rigid reinforcement in the welding area, suppressing the alternating stress transmitted to the weld from large-area bulging. Simultaneously, a buffer space matching the gas production is reserved on the cell 30 side to facilitate gas discharge from the cell 30, reducing cell 30 expansion and thus lowering its internal resistance and improving fast-charging overcurrent capability. This achieves a simultaneous improvement in energy density, reliability, and safety.

[0086] The battery 100 has a complex chemical system inside, and there are many factors that affect the gas generation and large-area expansion of the battery 100. By setting a first protrusion 15 on the long side of the battery 100 casing 10, the bonding wire at the opening 11 of the battery 100 casing 10 is strengthened. After the large area of ​​the battery 100 expands, the strengthened opening 11 better suppresses the tensile force on the bonding wire due to the large-area expansion. At the same time, by adjusting the overall capacity of the battery 100, the size of the first protrusion 15, the area ratio of the end face of the cell opening end to the large area of ​​the cell 30, and the mass content of silicon element in the large area of ​​the casing 10, the overall strength of the bonding wire at the opening of the battery 100 casing 10 is ensured, and the bonding wire at the long side of the casing 10 is prevented from cracking preferentially. At the same time, it prevents the overall energy density inside the battery 100 from being low and the space utilization from being poor, which would affect the overall range of the battery 100.

[0087] If the value of A / (x×y×z) is too small, the buffer space margin will be too large, the energy density will decrease, and the thinning of the shell 10 will increase the risk of forming cracks. If the value of A / (x×y×z) is too large, the long side of the opening 11 of the shell 10 will not receive sufficient local rigidity reinforcement in the welding zone. The weld will be in a high alternating tensile-shear stress zone, which will easily lead to fatigue cracks. The fluidity of the laser weld pool will be insufficient, the weld throat width will be reduced, the geometric stress concentration factor of the weld will increase, and the expansion force of the battery cell 30 will easily be directly superimposed on the shell 10, further amplifying the weld strain.

[0088] In one feasible implementation, refer to Figure 6 As shown, in the third direction D3, the end of the first protrusion 15 near the opening 11 is flush with the edge of the surface where the opening 11 is located. In the third direction D3 (i.e., the height direction of the housing 10), the proximal end face of the first protrusion 15 is coplanar with the end face where the opening 11 of the housing 10 is located. The flush arrangement minimizes the distance between the root of the first protrusion 15 and the weld initiation point, eliminates stress concentration caused by the step height difference, and cuts off the bulging deformation of the first inner surface 13 at the edge of the opening, preventing the deformation from continuing to be transmitted to the weld.

[0089] In another feasible implementation, refer to Figure 8 As shown, in the third direction D3, the end of the first protrusion 15 near the opening 11 is spaced apart from the surface where the opening 11 is located. In the third direction D3 (i.e., the height direction of the housing 10), a gap is maintained between the near end face of the first protrusion 15 and the end face where the opening 11 of the housing 10 is located. This gap area forms a deformation buffer zone. When the first inner surface 13 bulges and deforms, the wall of the housing 10 can bend within this gap area, absorbing part of the expansion displacement, preventing the bulging deformation from continuing to be transmitted to the weld, thereby inhibiting the initiation and propagation of fatigue cracks, and improving the structural stiffness and fatigue strength of the weld area.

[0090] Preferably, on the third direction D3, the distance between the end of the first protrusion 15 near the opening 11 and the surface where the opening 11 is located is between 0.3mm and 2.8mm. Specifically, it can be 0.3mm, 0.5mm, 1mm, 1.3mm, 1.5mm, 2mm, 2.3mm, or 2.8mm, and the value can be any value between 0.3mm and 2.8mm, as listed above. This avoids the laser welding heat-affected zone from being too close to the first protrusion 15, which would easily cause fatigue cracks to form at the root of the first protrusion 15, and also avoids weakening the constraint of the first protrusion 15 on bulging deformation. The distance between the end of the first protrusion 15 near the opening 11 and the surface where the opening 11 is located within this preset range avoids the root of the first protrusion 15 from falling directly into the welding heat-affected zone, maintains the constraint efficiency of the first protrusion 15 on large-area bulging, and does not require increasing the height of the shell 10.

[0091] On the third direction D3, the ratio of the size of the first protrusion 15 to the size of the first inner surface 13 on the parallel third direction D3 is between 0.0014 and 0.1. The size of the first protrusion 15 ranges from 0.1 mm to 15 mm, and the size of the first inner surface 13 ranges from 70 to 700 mm.

[0092] The ratio of the size of the first protrusion 15 to the size of the first inner surface 13 in the parallel third direction D3 can be 0.0014, 0.0058, 0.015, 0.028, 0.039, 0.058, 0.073, or 0.1. The value can be one of the aforementioned values ​​or any value between 0.0014 and 0.1. This can create a sufficiently long reinforcing region in the third direction D3, significantly reducing large-area bulging deflection, preventing bulging deformation from continuing to propagate to the weld, thereby inhibiting fatigue crack initiation and propagation, and improving the structural stiffness and fatigue strength of the weld area, while also avoiding excessive encroachment on the space of the receiving cavity 12.

[0093] If the ratio of the size of the first protrusion 15 to the size of the first inner surface 13 in the parallel third direction D3 is too small, the height dimension of the first protrusion 15 will be too short relative to the height of the shell 10. The first protrusion 15 will not be able to form sufficient buffer due to insufficient effective height. The large bulge of the shell 10 can still be transmitted to the surface where the opening 11 is located, resulting in poor reinforcement effect on the weld and easy cracking of the weld.

[0094] If the ratio of the size of the first protrusion 15 to the size of the first inner surface 13 in the parallel third direction D3 is too large, the height dimension of the first protrusion 15 will be too long relative to the height of the housing 10, occupying too much internal space of the cavity 12, reducing the energy density of the battery 100. At the same time, the housing 10 cannot expand properly, and the gas inside the cell 30 cannot be discharged in time, resulting in high internal resistance of the cell 30 and reduced current carrying capacity of the battery 100.

[0095] In one feasible implementation, refer to Figure 9 As shown, the first protrusion 15 has a wedge-shaped structure. Specifically, in the third direction D3, the first protrusion 15 has a first end and a second end. The first end is closer to the opening 11 than the second end. The dimension of the first end in the first direction D1 is greater than the dimension of the second end in the first direction D1, and the difference in size is between 0.1mm and 1.3mm. Specifically, it can be 0.1mm, 0.3mm, 0.6mm, 1.9mm, 1.2mm, or 1.3mm. The value can be one of the aforementioned values ​​or any value between 0.1mm and 1.3mm.

[0096] The first protrusion 15 can provide gradual stiffness. The first end can increase the moment of inertia of the section at the edge of the opening 11, while the second end can provide sufficient expansion space for the cell 30. If the dimensional difference is too small, the wedge shape is insufficient, the first protrusion 15 is close to uniform thickness, the stress concentration area at the edge of the surface where the opening 11 is located fails to obtain a locally increased moment of inertia, and the weld seam still bears high alternating tensile-shear stress, reducing the improvement in fatigue life. If the dimensional difference is too large, the inward protrusion 17 at the first end is too large, occupying too much space in the cavity 12, and the energy density of the battery 100 decreases.

[0097] Preferably, the dimension of the first protrusion 15 decreases linearly in the first direction D1 along the extension direction from the first end to the second end. This forms a continuous wedge-shaped slope, which facilitates processing and shaping, and has a constant slope without abrupt changes. The linear decrease causes the moment of inertia of the cross-section to decrease continuously along the third direction D3, and the bulging stress is uniformly released along the slope, avoiding stress abrupt changes. At the same time, the effective space of the receiving cavity 12 is maintained, and the energy density of the battery 100 is not reduced.

[0098] In one feasible implementation, refer to Figure 10As shown, the first protrusion 15 is composed of two segments. Specifically, in the third direction D3, the first protrusion 15 includes a first segment 151 and a second segment 152. The first segment 151 is closer to the opening 11 than the second segment 152. The minimum dimension of the first segment 151 in the first direction D1 is greater than the maximum dimension of the second segment 152 in the first direction D1. The second segment 152 has a first end and a second end. The first end is connected to the first segment 151, and the dimension of the first end in the first direction D1 is greater than the dimension of the second end in the first direction D1. The first segment 151 has a cuboid structure, and the second segment 152 has a wedge-shaped structure. The first segment, with its thicker upper section and thinner lower section, forms a stepped-decreasing composite profile. This profile provides a higher moment of inertia, intercepting the bulging stress transmitted to the first segment 151 and preventing further transmission of bulging deformation to the weld. This inhibits fatigue crack initiation and propagation, improving the structural stiffness and fatigue strength of the weld area. Furthermore, because the first segment 151 has a uniform total thickness, it is less prone to burn-through during welding, resulting in better weld reinforcement. The second segment 152 releases the bulging stress in a linearly increasing manner, ensuring a smooth decrease in bulging stress and reducing space loss in the cavity 12.

[0099] On the third-party direction D3, the ratio of the size of the first segment 151 to the size of the second segment 152 is between 1 and 12. The length of the first segment 151 is between 0.5 mm and 5 mm, and the length of the second segment 152 is between 0.1 mm and 5 mm. Specifically, the ratio of the size of the first segment 151 to the size of the second segment 152 can be 1, 3, 5, 7, 9, or 12, and can be any value between 1 and 12. Within this range, the weld at the opening 11 obtains a sufficient moment of inertia, preventing bulging deformation from continuing to propagate to the weld, thereby inhibiting the initiation and propagation of fatigue cracks and improving the structural stiffness and fatigue strength of the weld area. At the same time, the effective space of the cavity 12 is maintained, and the volumetric energy density of the battery 100 is not reduced.

[0100] If the ratio of the size of the first segment 151 to the size of the second segment 152 is too small, the weld reinforcement effect will be insignificant; if the ratio is too large, the first protrusion 15 will occupy too much internal space of the shell 10 and restrict the expansion of the shell 10.

[0101] In one feasible implementation, refer to Figure 11As shown, the housing 10 includes a first wall 16 disposed opposite to the cover plate 20 along a third direction D3. Along the third direction D3, the ratio of the shortest distance between the surface of the first protrusion 15 and the surface of the first wall 16 to the size of the housing 10 is between 0.8 and 0.98. Specifically, the ratio can be 0.8, 0.82, 0.86, 0.9, 0.9, 0.92, 0.96, or 0.98, and can be any value between 0.8 and 0.98. If the ratio is too small, the shortest distance between the top of the first protrusion 15 and the surface of the first wall 16 is compressed, reducing the effective height inside the housing 10. The total amount of cyclic expansion and gas production of the battery cell 30 remains unchanged, resulting in insufficient available buffer space. If the ratio is too large, the edge stress concentration area on the surface where the opening 11 is located fails to obtain a locally increased moment of inertia. The weld still bears high alternating tensile-shear stress, making the weld prone to fatigue cracks and reducing the fatigue life of the weld.

[0102] The housing 10 includes a first wall 16 disposed opposite to the cover plate 20 along a third direction D3. The first wall 16 is integrally formed with the wall containing the first inner surface 13, forming a seamless bottom corner and eliminating circumferential welds. The housing 10 can freely extend in the bottom direction during cyclic expansion, ensuring the connection strength between the first wall 16 and the large surface of the housing 10. At this time, it is limited that 110Ah / mm≤A / (x×y×z)≤300000Ah / mm. Specifically, the values ​​can be 110Ah / mm, 200Ah / mm, 250Ah / mm, 1000Ah / mm, 3000Ah / mm, 8000Ah / mm, 10000Ah / mm, 50000Ah / mm, 70000Ah / mm, 100000Ah / mm, 119050Ah / mm, 150000Ah / mm, 200000Ah / mm, 220000Ah / mm, 250000Ah / mm, or 300000Ah / mm. These values ​​can be the ones listed above or any value between 110Ah / mm and 300000Ah / mm. This allows the first protrusion 15 on the large sidewall to independently bear the expansion constraint function, avoiding the space waste and stiffness redundancy caused by adding another first protrusion 15 to the bottom surface, and ensuring that the energy density of the battery 100 does not decrease.

[0103] In one feasible embodiment, the housing 10 includes two first walls 16 disposed opposite to each other in the third direction D3. Each of the two first walls 16 is provided with an opening 11. Two cover plates 20 are provided, and the cover plates 20 are welded to the corresponding openings 11. The housing 10 is provided with an opening 11 at each end in the third direction D3, forming a through configuration. Each of the two openings 11 is closed by a cover plate 20, forming a double-sided weld seal, which facilitates the assembly of the battery cell 30 and avoids damage to the battery cell 30 during the assembly process. The welds at both ends are simultaneously in the tensile-shear alternating stress zone. At this time, the limit is 1000Ah / mm≤A / (x×y×z)≤35000Ah / mm. Specifically, the values ​​can be 1000Ah / mm, 3000Ah / mm, 8000Ah / mm, 10000Ah / mm, 50000Ah / mm, 70000Ah / mm, 100000Ah / mm, 119050Ah / mm, 150000Ah / mm, 200000Ah / mm, 220000Ah / mm, 250000Ah / mm, 300000Ah / mm, 320000Ah / mm, or 349655Ah / mm. The values ​​can be the ones listed above, or any value between 1000Ah / mm and 349655Ah / mm. This ensures that both openings 11 on both sides have high cross-sectional moments of inertia, reducing the alternating stress amplitude of the welds on both sides. This not only provides local rigid reinforcement to the long side of the opening 11 in the welding area, suppressing the alternating stress transmitted to the weld from large-area bulging, but also reserves a buffer space on the cell 30 side that matches the gas production, so that the gas can be discharged from the inside of the cell 30, reducing the expansion of the cell 30, thereby reducing the internal resistance of the cell 30 and improving the fast charging overcurrent capability.

[0104] The four corner regions at the junction of the large and small faces of shell 10 have the lowest geometric stiffness, and the corner strain is the greatest during bulging. If the first protrusion 15 is suspended above the large face, the corners remain free edges, and the weld areas at the corners are prone to cracking first due to high alternating strain. (Refer to...) Figure 12 As shown in the embodiments provided in this disclosure, at least one end of the first inner surface 13 is connected to the first protrusion 15 in the second direction D2, and the first protrusion 15 is connected to at least one side of the second inner surface 14. This forms a closed force transmission path of the large surface of the shell 10 – the first protrusion 15 – the small surface of the shell 10. By forming a lateral fixation between the first protrusion 15 and the second inner surface 14, the corner region changes from a free edge to a fixed edge, thereby increasing the moment of inertia of the section. The bulging stress is attenuated earlier at the corner, and the fatigue crack initiation location shifts from the corner to the central high-stiffness region, which can improve the strength of the weld area and avoid the risk of weld cracking from the end.

[0105] In one feasible implementation, the first protrusion 15 is a continuous structure. The first protrusion 15 extends continuously in the second direction D2 without interruption or gap, forming a continuous reinforcing rib connecting the edge of the large surface of the shell 10. The entire opening 11 obtains a uniform moment of inertia of the cross section. The bulging stress is evenly distributed along the first protrusion 15 without stress abrupt change points, thus avoiding gaps from becoming fatigue crack sources.

[0106] In another feasible implementation, refer to Figure 13 As shown, in the second direction D2, the first protrusion 15 includes at least two spaced-apart first sub-protrusions 153. A longitudinal expansion channel is formed between adjacent first sub-protrusions 153. Each first sub-protrusion 153 causes the local cross-sectional moment of inertia to be superimposed, providing multiple rigid supports along the entire length of the weld, suppressing the transmission of bulging stress to the weld. When the internal gas pressure rises, the longitudinal expansion channel between adjacent first sub-protrusions 153 preferentially generates elastic bulging, absorbing displacement and preventing the overall bulging from concentrating on the weld end, increasing the expansion space to accommodate gas, and improving the fast charging capability.

[0107] In the second direction D2, the spacing between two adjacent first sub-protrusions 153 is between 3mm and 50mm. Specifically, it can be 3mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, or 50mm, and the values ​​can be either those listed above or any value between 3mm and 50mm. Within the preset range, the gas has sufficient expansion space, the internal resistance does not increase, and the fast charging capability is maintained; adjacent sub-protrusions still maintain sufficient density, the weld seam obtains a uniform rigid support along its entire length, and the expansion stress is attenuated in segments, achieving synergistic optimization of expansion space and reinforcement effect.

[0108] If the distance between two adjacent first sub-protrusions 153 is too small, the expansion channel width will be insufficient. After the cell 30 generates gas during circulation, the gas cannot be quickly guided to the opening 11, resulting in a local increase in gas pressure, an increase in DC internal resistance, and a limitation on the overcurrent capacity of the battery 100. If the distance between two adjacent first sub-protrusions 153 is too large, the weld will lack rigid support in the interval area between the first sub-protrusions 153, the moment of inertia of the section will decrease, the strengthening effect of the first protrusion 15 on the weld will be poor, and the fatigue life of the weld will decrease.

[0109] In one feasible implementation, refer to Figure 14As shown, in the second direction D2, at least one end of the first inner surface 13 is spaced apart from the first protrusion 15. In the second direction D2, a non-zero gap region is maintained between the second inner surface 14 and the side edge of the first protrusion 15, forming a corner expansion channel. This provides sufficient space to accommodate gas, facilitating the discharge of gas from the inside of the cell 30 and preventing rigid obstruction by the sidewall of the first protrusion 15. This reduces the internal resistance of the cell 30 and improves the overcurrent capacity of the battery 100.

[0110] The distance between the end of the first inner surface 13 and the first protrusion 15 is between 0.5mm and 5mm. Specifically, it can be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm. The value can be one of the aforementioned values ​​or any value between 0.5mm and 5mm. Within this preset range, the housing 10 provides sufficient space to accommodate the gas, improving the fast charging capability. The side edge of the first protrusion 15 still maintains an effective connection distance with the small face of the housing 10, and the stress amplitude in the corner weld area decreases, which can improve the strength of the weld area and avoid the risk of weld cracking from the end.

[0111] If the distance between the end of the first inner surface 13 and the first protrusion 15 is too small, the gas cannot be quickly guided to the opening 11, the local gas pressure increases, the DC internal resistance increases, thereby reducing the overcurrent capacity of the battery 100. If the distance between the end of the first inner surface 13 and the first protrusion 15 is too large, the side edge of the protrusion is far away from the small face, the moment of inertia of the corner area is sharply reduced, the weld is still subjected to high alternating tensile-shear stress, fatigue cracks are easily generated at the weld, and the fatigue life at the weld is reduced.

[0112] In one feasible implementation, the first protrusion 15 is a continuous structure. The first protrusion 15 extends continuously in the second direction D2 without interruption or gap, forming a continuous reinforcing rib connecting the edge of the large surface of the shell 10. The entire opening 11 obtains a uniform moment of inertia of the cross section. The bulging stress is evenly distributed along the first protrusion 15 without stress abrupt change points, thus avoiding gaps from becoming fatigue crack sources.

[0113] In another feasible implementation, refer to Figure 14 As shown, in the second direction D2, the first protrusion 15 includes at least two spaced-apart first sub-protrusions 153. A longitudinal expansion channel is formed between adjacent first sub-protrusions 153. Each first sub-protrusion 153 causes the local cross-sectional moment of inertia to be superimposed, providing multiple rigid supports along the entire length of the weld, suppressing the transmission of bulging stress to the weld. When the internal gas pressure rises, the longitudinal expansion channel between adjacent first sub-protrusions 153 preferentially generates elastic bulging, absorbing displacement and preventing the overall bulging from concentrating on the weld end, increasing the expansion space to accommodate gas, and improving the fast charging capability.

[0114] In the second direction D2, the spacing between two adjacent first sub-protrusions 153 is between 3mm and 40mm. Specifically, it can be 3mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, or 40mm, and the values ​​can be either those listed above or any value between 3mm and 40mm. Within the preset range, the gas has sufficient expansion space, the internal resistance does not increase, and the fast charging capability is maintained; adjacent sub-protrusions still maintain sufficient density, the weld seam obtains a uniform rigid support along its entire length, and the expansion stress is attenuated in segments, achieving synergistic optimization of expansion space and reinforcement effect.

[0115] If the distance between two adjacent first sub-protrusions 153 is too small, the expansion channel width will be insufficient. After the cell 30 generates gas during circulation, the gas cannot be quickly guided to the opening 11, resulting in a local increase in gas pressure, an increase in DC internal resistance, and a limitation on the overcurrent capacity of the battery 100. If the distance between two adjacent first sub-protrusions 153 is too large, the weld will lack rigid support in the interval area between the first sub-protrusions 153, the moment of inertia of the section will decrease, the strengthening effect of the first protrusion 15 on the weld will be poor, and the fatigue life of the weld will decrease.

[0116] In the embodiments provided in this disclosure, the ratio of the size of the first protrusion 15 to the size of the housing 10 in the second direction D2 is between 0.8 and 1. Specifically, the ratio can be 0.8, 0.82, 0.86, 0.9, 0.9, 0.92, 0.96, or 1, and the value can be any value between 0.8 and 1, as listed above. Within this preset range, the weld seam has a continuous rigid backing, the bulging stress is uniformly attenuated, the remaining expansion channels still meet the cyclic expansion requirements of the cell 30, the internal resistance does not increase, and the overcurrent capacity of the battery 100 is maintained.

[0117] If the ratio of the size of the first protrusion 15 to the size of the housing 10 is too small, the weld lacks rigid support, the moment of inertia of the section decreases, the strengthening effect of the first protrusion 15 on the weld is poor, and the fatigue life of the weld decreases. If the ratio of the size of the first protrusion 15 to the size of the housing 10 is too large, the expansion space is insufficient, the gas generated by the cell 30 during circulation cannot be quickly guided to the opening 11, the local gas pressure increases, the DC internal resistance increases, and the overcurrent capacity of the battery 100 is limited.

[0118] In the second direction D2, the size of the first protrusion 15 is between 115mm and 600mm. Specifically, it can be 115mm, 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, or 600mm. The value can be one of the aforementioned values ​​or any value between 115mm and 600mm. Within this preset range, the entire length of the weld seam obtains a continuous rigid backing, the expansion stress is uniformly attenuated, the remaining expansion channels still meet the cell's 30-cycle capacity expansion gas generation requirements, the internal resistance does not increase, and the battery's 100-current capacity is maintained.

[0119] If the size of the first protrusion 15 is too small, the weld lacks rigid support, the moment of inertia of the section decreases, the strengthening effect of the first protrusion 15 on the weld is poor, and the fatigue life of the weld decreases. If the size of the first protrusion 15 is too large, the expansion space is insufficient, the gas generated by the cell 30 in the cycle cannot be quickly guided to the opening 11, the local gas pressure increases, the DC internal resistance increases, and the overcurrent capacity of the battery 100 is limited.

[0120] A first protrusion 15 is provided in the second direction D2, within the range of 1 / 3 to 2 / 3 of the first inner surface 13. The size of the first protrusion 15 along the first direction D1 ranges from 0.3mm to 1.5mm. Specifically, it can be 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1.1mm, 1.3mm, or 1.5mm. The value can be any value between 0.3mm and 1.5mm, as listed above. The large surface of the shell 10 is in the maximum deflection zone between 1 / 3 and 2 / 3. Under the action of internal air pressure, the stress in this section is the highest, and the bulging stress is easily transmitted to both ends, directly pulling the weld at the long side of the cover plate 20. By providing the first protrusion 15 in this section, the transmission of bulging stress can be attenuated. The transmission path of bulging stress to the weld is cut off, preventing the bulging deformation from continuing to be transmitted to the weld, thereby inhibiting the initiation and propagation of fatigue cracks and improving the structural stiffness and fatigue strength of the weld area.

[0121] If the size of the first protrusion 15 along the first direction D1 is too small, the strengthening effect of the first protrusion 15 on the weld will be poor, and the fatigue life of the weld will decrease. If the size of the first protrusion 15 along the first direction D1 is too large, the expansion space will be insufficient, and the gas generated by the cell 30 in the cycle cannot be quickly guided to the opening 11, resulting in a local increase in gas pressure, an increase in DC internal resistance, and a limitation on the overcurrent capacity of the battery 100.

[0122] In one feasible implementation, the wall thickness at the location of the first protrusion 15 is greater than the wall thickness at other locations along the first direction D1. The high wall thickness region overlaps with the first protrusion 15 to form a double-layer reinforcement, blocking the transmission of bulging stress to the weld and preventing weld cracking. The wall thickness is maintained at other locations to ensure maximum internal space of the receiving cavity 12, without encroaching on the space of the battery cell 30; at the same time, the overall mass of the housing 10 is reduced.

[0123] In the embodiments provided in this disclosure, reference is made to Figure 15 As shown, the inner surface of the receiving cavity 12 also includes a transition surface. The first inner surface 13 and the second inner surface 14 are connected by the transition surface. A protrusion 17 is provided on the transition surface. The protrusion 17 is a limiting boss 22 protruding towards the battery cell 30. The cover plate 20 abuts against the protrusion 17 to form a pre-pressurized contact.

[0124] The protrusion 17 transforms the corner edges of the large and small faces of the shell 10 into closed triangular regions, increasing the moment of inertia of the section and enhancing the connection stiffness between the large and small faces of the shell 10. Expansion stress is blocked by the protrusion 17 at the corners, improving the strength of the weld area and preventing the risk of weld cracking at the corners. When the cover plate 20 is placed, the top surface of the boss 22 acts as a mechanical limiter, ensuring that the cover plate 20 is flush with the end face where the opening 11 of the shell 10 is located, preventing misalignment between the cover plate 20 and the shell 10 from affecting the weld strength.

[0125] Preferably, the cover plate 20 is welded to the protrusion 17. After the lower surface of the cover plate 20 directly abuts against the top surface of the protrusion 17 on the transition surface, a fusion weld is performed along the circumference of the protrusion 17 to solidify the cover plate 20, the protrusion 17, and the corner area of ​​the shell 10 into a continuous rigid node, thereby increasing the moment of inertia of the corner section, further improving the strength of the weld end, and preventing weld cracking.

[0126] Furthermore, adjacent first inner surfaces 13 and second inner surfaces 14 are connected by transition surfaces, each with a protrusion 17. The large surface of the housing 10, the transition surface, and the small surface of the housing 10 form a closed reinforcing ring at the opening corner, improving the connection strength between the large and small surfaces of the housing 10. When the battery cell 30 generates gas, under the action of internal gas pressure, the deflection at the center of the large surface of the housing 10 diffuses outward along the wall thickness direction. The closed reinforcing rings at the four corners can improve the moment of inertia of the cross section in multiple directions, preventing overall deformation of the large surface. The top surfaces of the protrusions 17 at the four corners are coplanar, forming a mechanical positioning reference. The cover plate 20 and the housing 10 remain in a non-misaligned state, improving the positioning accuracy and welding strength of the cover plate 20.

[0127] In one feasible implementation, refer to Figure 15As shown, the first protrusion 15 is connected to the protrusion 17 to form an integral rigid node, which improves the strength of the connection between the large surface and the short surface of the shell 10. When the shell 10 bulges, the bulging stress of the large surface of the shell 10 is transmitted to the corner along the first protrusion 15 and diffused to the small surface of the shell 10 through this node, thereby increasing the moment of inertia of the section, reducing deformation, and preventing the bulging deformation from continuing to be transmitted to the weld, thereby inhibiting the initiation and propagation of fatigue cracks and improving the structural stiffness and fatigue strength of the area where the weld is located.

[0128] In another feasible implementation, refer to Figure 16 As shown, the first protrusion 15 and the protrusion 17 are spaced apart to form an expansion channel for the production gas to pass through. The distance between the first protrusion 15 and the protrusion 17 is between 0.5mm and 50mm. Specifically, it can be 0.5mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, or 50mm. The value can be one of the aforementioned values ​​or any value between 0.5mm and 50mm. Within this range, the gas can be rapidly guided along the channel to the opening 11 in real time without increasing the internal resistance. The first protrusion 15 retains sufficient length to continue providing rigid backing for the long side weld, preventing bulging deformation from continuing to propagate to the weld, thereby inhibiting the initiation and propagation of fatigue cracks and improving the structural stiffness and fatigue strength of the weld area.

[0129] If the distance between the first protrusion 15 and the protrusion 17 is too small, the gas generated by the cell 30 during circulation cannot be quickly guided to the opening 11, resulting in increased local gas pressure, increased DC internal resistance, and limited overcurrent capacity of the battery 100. If the distance between the first protrusion 15 and the protrusion 17 is too large, the weld lacks rigid support, the moment of inertia of the section decreases, the strengthening effect of the first protrusion 15 on the weld is poor, and the fatigue life of the weld decreases.

[0130] In the first direction D1, the wall dimension at the location of protrusion 17 is larger than the wall dimension at the location of the first protrusion 15. The wall thickness of the section where the first protrusion 15 is located is smaller than the wall thickness of the section where protrusion 17 is located. The thicker top surface of protrusion 17 forms a rigid limiting platform, which provides higher compressive rigidity when the cover plate 20 abuts, and prevents sinking deformation during welding. This ensures that the end face of the cover plate 20 and the opening 11 of the shell 10 remain coplanar, preventing weak welding caused by misalignment. A high-rigidity node is formed at the corner, reducing corner deformation and improving the connection strength between the large and small faces of the shell 10. This prevents deformation at the connection between the large and small faces of the shell 10 from affecting the weld strength at the opening 11.

[0131] Furthermore, on the third direction D3, the minimum distance between the protrusion 17 and the surface where the opening 11 is located is not less than the minimum distance between the first protrusion 15 and the surface where the opening 11 is located. The top of the protrusion 17 is not higher than the top of the first protrusion 15, which can better limit the cover plate 20, prevent the cover plate 20 from partially lifting or tilting, and prevent poor fit between the cover plate 20 and the opening 11, which would lead to a decrease in weld strength.

[0132] In the embodiments provided in this disclosure, reference is made to Figure 17 as well as Figure 18 As shown, the second inner surface 14 is provided with a second protrusion 18, which is close to or continues on the surface where the opening 11 is located. The second protrusion 18 protrudes along the second inner surface 14 toward the cell 30, and the protrusion direction of the second protrusion 18 points toward the cell 30, that is, it protrudes inward along the second direction D2, so as to avoid the second protrusion 18 encroaching on the battery module space. The original gap between the surface of the cell 30 and the inner surface of the housing 10 is used to accommodate the second protrusion 18, thus ensuring the energy density and space utilization of the battery 100. The distance between the second protrusion 18 and the end face where the opening 11 of the housing 10 is located is ≤5mm, or it is directly connected to the end face where the opening 11 is located. This makes the root of the reinforcing rib as close as possible to the weld, preventing the large-area bulging deformation of the housing 10 from being transmitted to the weld.

[0133] The second protrusion 18 can increase the moment of inertia of the short side section, prevent the bulging deformation from continuing to be transmitted to the weld, thereby inhibiting the initiation and propagation of fatigue cracks, improving the structural stiffness and fatigue strength of the area where the weld is located, and avoiding excessive encroachment on the space of the receiving cavity 12.

[0134] After the second protrusion 18 is added to the small face of the shell 10, three rigid nodes are formed in the four corner weld areas: the first protrusion 15, the second protrusion 18, and the protrusion 17, which improves the overall rigidity. The second protrusion 18 protrudes inward 17, and the effective volume of the receiving cavity 12 is occupied. At this time, it is limited that 1500Ah / mm ≤ A / (x×y×z) ≤ 349655Ah / mm. Specifically, it can be 1500Ah / mm, 3000Ah / mm, 8000Ah / mm, 10000Ah / mm, 50 The values ​​can be 000Ah / mm, 70000Ah / mm, 100000Ah / mm, 119050Ah / mm, 150000Ah / mm, 200000Ah / mm, 220000Ah / mm, 250000Ah / mm, 300000Ah / mm, 320000Ah / mm, or 349655Ah / mm. These values ​​can be specifically listed above or any value between 1500Ah / mm and 349655Ah / mm. This reduces the risk of weld cracking while preserving expansion and venting space.

[0135] Furthermore, the first protrusion 15 extends continuously along the second direction D2, and the second protrusion 18 extends continuously along the first direction D1. Both the first protrusion 15 and the second protrusion 18 are continuous structures. The first protrusion 15 extends continuously along the second direction D2, and the second protrusion 18 extends continuously along the first direction D1, without interruption or gaps, forming a continuous reinforcing rib connecting the edge of the large surface of the shell 10. The entire opening 11 obtains a uniform moment of inertia, and the bulging stress is evenly distributed along the first protrusion 15 and the second protrusion 18, without stress abrupt change points, thus avoiding gaps becoming fatigue crack sources.

[0136] In another feasible embodiment, in the second direction D2, the first protrusion 15 includes at least two first sub-protrusions 153 spaced apart along the second direction D2, and the second protrusion 18 includes at least two second sub-protrusions 181 spaced apart along the first direction D1. Longitudinal expansion channels are formed between adjacent first sub-protrusions 153 and between adjacent second sub-protrusions 181. Each first sub-protrusion 153 and second sub-protrusion 181 causes the local cross-sectional moments of inertia to be superimposed, providing multiple rigid supports along the entire weld length, suppressing the transmission of bulging stress to the weld. When the internal gas pressure rises, the longitudinal expansion channels between adjacent first sub-protrusions 153 and adjacent second sub-protrusions 181 preferentially generate elastic bulging, absorbing displacement and preventing the overall bulging from concentrating on the weld end, increasing the expansion space to accommodate gas, and improving the fast charging capability.

[0137] In the second direction D2, the distance between two adjacent first sub-protrusions 153 is between 0.5mm and 40mm. Specifically, it can be 0.5mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, or 40mm, and the value can be any value between 0.5mm and 40mm. In the first direction D1, the distance between two adjacent second sub-protrusions 181 is between 0.5mm and 20mm. Specifically, it can be 0.5mm, 5mm, 10mm, 15mm, or 20mm, and the value can be any value between 0.5mm and 20mm.

[0138] Within the preset range, the gas has sufficient expansion space, the internal resistance does not increase, and the overcurrent fast charging capability is maintained; adjacent sub-protrusions still maintain sufficient density, the entire length of the weld obtains a uniform rigid support, the bulging stress is attenuated in segments, and the expansion space and strengthening effect are synergistically optimized.

[0139] If the spacing between two adjacent first sub-protrusions 153 and two adjacent second sub-protrusions 181 is too small, the expansion channel width will be insufficient. After the cell 30 generates gas through circulation, the gas cannot be quickly guided to the opening 11, resulting in a local increase in gas pressure, an increase in DC internal resistance, and a limitation on the overcurrent capacity of the battery 100. If the spacing between two adjacent first sub-protrusions 153 and two adjacent second sub-protrusions 181 is too large, the weld will lack rigid support in the interval areas between the first sub-protrusions 153 and the second sub-protrusions 181, reducing the moment of inertia of the cross section. The strengthening effect of the first protrusions 15 and the second protrusions 18 on the weld will be poor, and the fatigue life of the weld will decrease.

[0140] In the first direction D1, the ratio of the size of the second protrusion 18 to the size of the housing 10 is between 0.62 and 0.95. Specifically, the ratio can be 0.62, 0.82, 0.86, 0.9, 0.9, 0.92, or 0.95, and can be any value between 0.62 and 0.95, as listed above. Within this preset range, the weld seam has a continuous rigid backing, the bulging stress is uniformly attenuated, the remaining expansion channels still meet the cyclic expansion requirements of the cell 30, the internal resistance does not increase, and the overcurrent capacity of the battery 100 is maintained.

[0141] If the ratio of the size of the second protrusion 18 to the size of the housing 10 is too small, the weld lacks rigid support, the moment of inertia of the section decreases, the strengthening effect of the second protrusion 18 on the weld is poor, and the fatigue life of the weld decreases. If the ratio of the size of the second protrusion 18 to the size of the housing 10 is too large, the expansion space is insufficient, the gas generated by the cell 30 during circulation cannot be quickly guided to the opening 11, the local gas pressure increases, the DC internal resistance increases, and the overcurrent capacity of the battery 100 is limited.

[0142] In one feasible implementation, refer to Figure 6 As shown, in the first direction D1, the thickness of the wall where the first protrusion 15 is located is b, where b is in mm, and the value of b is limited to 0.1 mm to 2.5 mm, where 0.05 mm... 2 ≤x×b≤1mm 2 Specifically, the value can be 0.05mm. 2 0.15mm 2 0.25mm 2 0.35mm 2 0.45mm 2 0.55mm 2 0.65mm 2 0.75mm 2 0.85mm 2 0.95mm 2 or 1mm 2The value can be one of the values ​​listed above, or it can be 0.05mm. 2 -0.15mm 2 Any value between these ranges. Within this range, the local section moment of inertia is significantly increased, maintaining sufficient stiffness.

[0143] If the formula value of x×b is too small, the moment of inertia of the cross section will decrease, the strengthening effect of the first protrusion 15 on the weld will be poor, and the fatigue life of the weld will decrease. If the formula value of x×b is excessively occupied, the effective volume of the cavity 12 will be reduced, the expansion and gas generation buffer space of the cell 30 will be reduced, the local gas pressure will increase, the DC internal resistance will increase, and the overcurrent capacity of the battery 100 will be limited.

[0144] In the embodiments provided in this disclosure, reference is made to Figure 19 As shown, the battery cell 30 includes a battery cell body 34 and a tab 35. The tab 35 is electrically connected to the battery cell body 34. The tab 35 serves as a current collector extension, collecting the current generated by the battery cell body 34 and leading it to the terminal post 50. In the first direction D1, the orthographic projection of the battery cell body 34 on the first inner surface 13 is offset from the first protrusion 15, and the two do not overlap.

[0145] The tab 35 is disposed on one side of the positive / negative current collector and is separately / integrated with the current collector, and is electrically connected to the current collector to conduct the current on the corresponding current collector. The tab 35 is made of a metal material with good conductivity (such as copper, aluminum, or nickel).

[0146] During the cyclic expansion of the battery cell 30, the outer surface of the battery cell body 34 first bulges towards the center of the large surface (first inner surface 13) of the housing 10. Because the battery cell body 34 is offset from the first protrusion 15, the bulging part of the battery cell body 34 contacts the first inner surface 13, maintaining a safe gap between the battery cell body 34 and the first protrusion 15. This eliminates the risk of shearing or indentation of the battery cell body 34 by the edge of the first protrusion 15 during assembly or vibration, preventing diaphragm puncture or electrode breakage, and avoiding internal short circuits. Since the first protrusion 15 does not directly contact the battery cell body 34, the expansion stress of the battery cell body 34 is not directly transmitted to the first protrusion 15, reducing the impact of the battery cell 30 expansion on the weld and ensuring weld strength.

[0147] In another feasible embodiment, the battery cell 30 includes a battery cell body 34 and a tab 35. The tab 35 is electrically connected to the battery cell body 34. Along the first direction D1, the orthographic projection of the battery cell body 34 on the first inner surface 13 at least partially falls on the first protrusion 15. This improves the volume utilization of the receiving cavity 12 and correspondingly increases the energy density of the battery 100.

[0148] In the embodiments provided in this disclosure, the tab 35 extends towards the opening 11, serving as the output terminal of the cell 30. It extends directly towards the opening 11 along a third direction D3, thereby connecting with the terminal post 50. This shortens the current path, reduces DC resistance, and improves the overcurrent capacity of the battery 100. During cyclic fast charging, the Joule heat from the tab 35 is transferred to the weld of the opening 11 through the terminal post 50, subjecting the weld to thermo-mechanical alternating loads. Therefore, the requirement is defined as 110Ah / mm ≤ A / (x×y×z) ≤ 300000Ah / mm. Specifically, the values ​​can be 110Ah / mm, 1500Ah / mm, 3000Ah / mm, 8000Ah / mm, 10000Ah / mm, 50000Ah / mm, 70000Ah / mm, 100000Ah / mm, 119050Ah / mm, 150000Ah / mm, 200000Ah / mm, 220000Ah / mm, 250000Ah / mm, or 300000Ah / mm. These values ​​can be specifically those listed above, or any value between 110Ah / mm and 300000Ah / mm. This achieves a balance between current-carrying capacity and weld strength.

[0149] In the first direction D1, the tab 35 and the first protrusion 15 are spaced apart, with the distance between the tab 35 and the first protrusion 15 being between 0.1mm and 3.5mm. Specifically, the formula value can be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, or 3.5mm, and the value can be any value between 0.1mm and 3.5mm. Within this value range, the bending length of the tab 35 is minimized, the impedance does not increase, the current carrying capacity remains at the design value, the heat conduction path of the tab 35 is blocked by air, reducing the impact on the weld and maintaining the mechanical strength of the weld.

[0150] If the spacing is too small, the surface of the tab 35 will almost touch the sidewall of the first protrusion 15. The heat generated by the tab 35 will be directly conducted to the weld at the opening 11 through the first protrusion 15, causing the temperature in the weld area to rise. The superposition of thermo-mechanical alternating stress will make the weld more prone to fatigue cracking. If the spacing is too large, the tab 35 will need to be lengthened and bent to cross the increased spacing, resulting in a longer conductive path, increased DC resistance, and decreased overcurrent capacity of the battery 100. At the same time, it will occupy too much space in the cavity 12, reducing the energy density.

[0151] In one feasible implementation, refer to Figure 20As shown, the battery cell 30 includes multiple tabs 35, forming a parallel output of multiple tabs 35. Each tab 35 includes a positive tab and a negative tab, which are electrically connected to their respective terminals 50. Both the positive and negative tabs extend towards the opening 11 and are arranged along the second direction D2. The current path direction is perpendicular to the opening 11, thereby shortening the conductive length, reducing DC resistance, and correspondingly improving the overcurrent capacity of the battery 100.

[0152] Furthermore, the positive and negative tabs are spaced apart, running side-by-side in the second direction D2 but not touching, forming an insulating barrier to prevent direct conduction between the positive and negative tabs 35 and eliminate the risk of internal short circuits. The distance between the positive and negative tabs 35 is between 30mm and 270mm. Specifically, the distance can be 30mm, 60mm, 90mm, 120mm, 150mm, 180mm, 210mm, 240mm, or 270mm, and can be any value between 30mm and 270mm. Within this range, the heat generation zone of the tab 35 is evenly distributed along the second direction D2, the weld heat load is controllable, and the bending length of the tab 35 is minimized, improving the current carrying capacity.

[0153] If the spacing is too small, the heat generated by the tabs 35 will be concentrated. The heat generated by the tabs 35 will be directly conducted to the weld at the opening 11 through the first protrusion 15, resulting in an increase in temperature in the weld area. The superposition of thermo-mechanical alternating stress will make the weld more prone to fatigue cracking. If the spacing is too large, the tabs 35 need to be lengthened to cross the increased spacing, resulting in a longer conductive path, increased DC resistance, and decreased overcurrent capacity of the battery 100. At the same time, it will occupy too much space in the cavity 12, reducing the energy density.

[0154] In the embodiments provided in this disclosure, reference is made to Figure 19 as well as Figure 20 As shown, the second outer surface 32 is spaced apart along the second direction D2, and the second outer surface 32 is opposite to the second inner surface 14. The outer surface of the cell 30 also includes two third outer surfaces 33 spaced apart along the third direction D3. The tabs 35 are led out from the second outer surface 32 or the third outer surface 33. The current path of the tabs 35 is not directly facing the large surface (first inner surface 13) of the housing 10. When the cell 30 generates gas, the high-pressure gas flow preferentially rushes towards the channel opposite to the small surface or the opening 11 of the housing 10, avoiding direct vertical impact on the center of the large surface of the housing 10, so as to slow down the expansion of the housing 10 and avoid the bulging deformation being concentrated and transmitted to the long side weld between the large surface of the housing 10 and the cover plate 20, thereby inhibiting the initiation and propagation of fatigue cracks and improving the structural stiffness and fatigue strength of the weld area.

[0155] Furthermore, referring to Figure 20As shown, the tab 35 extends from the second outer surface 32 (i.e., the side opposite to the small facet of the housing 10). The heat from the tab 35 is transferred along the second direction D2 to the second outer surface 32, and then diffused through the second outer surface 32, thereby extending the path of heat to the large facet of the housing 10. The temperature rise in the weld area is reduced, the heat from the tab 35 is less likely to directly affect the weld, the thermo-mechanical alternating stress amplitude is reduced, and the weld strength is guaranteed.

[0156] In the embodiments provided in this disclosure, reference is made to Figure 21 As shown, the battery 100 includes an adapter 36 that connects the tab 35 and the terminal post 50 to facilitate the assembly of the battery cell 30. The adapter 36 includes a vertical section 361 and a horizontal section 362. The vertical section 361 faces the surface where the tab 35 is located and is connected to the tab 35. The horizontal section 362 extends along a third direction D3 toward the opening 11. The horizontal section 362 is located between the first inner surface 13 and the first outer surface. In the first direction D1, the orthographic projection of the horizontal section 362 on the first inner surface 13 at least partially falls on the first protrusion 15. The horizontal section 362 does not additionally encroach on the thickness direction space of the battery cell 30, thereby improving the volume utilization of the receiving cavity 12 and correspondingly increasing the energy density of the battery 100.

[0157] In one feasible implementation, the straight section 362 and the first protrusion 15 do not directly contact each other in the first direction D1 to avoid direct heat transfer and short circuit. The straight section 362 and the first protrusion 15 are spaced apart, with the spacing between them being between 3mm and 8mm, thus forming a buffer zone. Specifically, the spacing can be 3mm, 4mm, 5mm, 6mm, 7mm, or 8mm, and can be any value between 3mm and 8mm, as listed above. Within this range, the bending length of the adapter 36 is minimized, without increasing impedance, maintaining the predetermined current carrying capacity. The heat conduction path of the adapter 36 is blocked by the air layer, reducing the temperature rise in the weld area. The heat from the tab 35 is less likely to directly affect the weld, reducing the thermo-mechanical alternating stress amplitude and ensuring weld strength.

[0158] If the spacing is too small, the heat generated by the tab 35 will be conducted through the air to the first protrusion 15, and then to the weld at the opening 11, causing the temperature in the weld area to rise. The superposition of thermo-mechanical alternating stress makes the weld more prone to fatigue cracking. If the spacing is too large, the tab 35 needs to be lengthened to cross the increased spacing, resulting in a longer conductive path, increased DC resistance, and decreased overcurrent capacity of the battery 100. At the same time, it will occupy too much space in the cavity 12, reducing the energy density.

[0159] Since the tab 35 is led out through the adapter 36, the heat from the tab 35 needs to be conducted in a certain direction to reach the weld, making it less likely to directly affect the weld. Therefore, the temperature rise in the weld area is slowed down, the thermo-mechanical alternating stress amplitude decreases, and the risk of weld cracking is reduced. However, this also increases the conductive path, raises the DC resistance, and reduces the battery's 100% overcurrent capacity. Therefore, the limit is 1200Ah / mm ≤ A / (x×y×z) ≤ 349655Ah / mm. Specifically, the values ​​can be 1200Ah / mm, 1500Ah / mm, 3000Ah / mm, 8000Ah / mm, 10000Ah / mm, 50000Ah / mm, 70000Ah / mm, 100000Ah / mm, 119050Ah / mm, 150000Ah / mm, 200000Ah / mm, 220000Ah / mm, 250000Ah / mm, 300000Ah / mm, 320000Ah / mm, or 349655Ah / mm. The values ​​can be the ones listed above, or any value between 1200Ah / mm and 349655Ah / mm. This improves local stiffness and weld throat width without changing the lead-out path, offsetting impedance loss caused by path extension, while avoiding excessive reinforcement that could lead to encroachment on the cavity 12 space or embrittlement of the heat-affected zone.

[0160] In one feasible implementation, refer to Figure 22 as well as Figure 23 As shown, the outer surface of the housing 10 is provided with a third protrusion 19. The third protrusion 19 is integrally stamped into the outer wall of the large surface of the housing 10 to form an outer reinforcing rib. The third protrusion 19 and the first protrusion 15 are located on opposite surfaces of the same wall of the housing 10, and the first protrusion 15 and the third protrusion 19 share the same wall body. In the first direction D1, the orthographic projection of the third protrusion 19 on the first inner surface 13 at least partially coincides with the orthographic projection of the first protrusion 15 on the first inner surface 13. The inner reinforcing rib formed by the first protrusion 15 and the outer reinforcing rib formed by the third protrusion 19 constitute a superimposed reinforcing region.

[0161] Because the third protrusion 19 is provided outward, the protrusion distance of the third protrusion 19 protruding inward can be reduced, thereby increasing the effective space of the receiving cavity 12, increasing the expansion gap of the cell 30, and allowing gas to be quickly guided to the opening 11 along the channel formed between the first protrusion 15 and the cell 30, reducing internal resistance and improving the current carrying capacity of the battery 100.

[0162] Furthermore, in the first direction D1, the dimension of the third protrusion 19 is between 0.1mm and 1.5mm. Specifically, the value can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, or 1.5mm. The value can be any value between 0.1mm and 1.5mm, as listed above. Within this range, excessive encroachment on the effective space of the receiving cavity 12 within the battery 100 is avoided, as is a decrease in the space utilization rate of the battery pack.

[0163] If the size of the third protrusion 19 is too small, the increase in the cross-sectional moment of inertia provided by the third protrusion 19 will be reduced, and it will not provide sufficient stiffness. In order to maintain the anti-bulging ability, the protrusion distance of the first protrusion 15 needs to be increased, which will cause the effective space of the accommodating cavity 12 to be occupied, the expansion of the cell 30 and the gas generation buffer space to be compressed, the gas discharge resistance in the cell 30 will increase, the DC internal resistance will increase, and the overcurrent capacity of the battery 100 will decrease.

[0164] If the size of the third protrusion 19 is too large, the gap between adjacent batteries 100 needs to be increased accordingly, which reduces the space utilization rate of the battery pack.

[0165] In one feasible implementation, the ratio of the size of the first protrusion 15 to the size of the third protrusion 19 in the first direction D1 is between 0.5 and 15. Specifically, the value can be 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. The value can be any value between 0.5 and 15, as listed above. Within this range, the third protrusion 19 can increase its moment of inertia by a certain amount, thereby reducing the protrusion distance of the first protrusion 15, maintaining sufficient expansion and venting space within the receiving cavity 12, without increasing the gap between adjacent batteries 100 in the battery pack, thus improving space utilization.

[0166] If the ratio of the size of the first protrusion 15 to the size of the third protrusion 19 is too small, the distance of the third protrusion 19 will be too large, the gap between adjacent batteries 100 will need to be increased accordingly, and the space utilization rate of the battery pack will decrease.

[0167] If the ratio of the size of the first protrusion 15 to the size of the third protrusion 19 is too large, the incremental moment of inertia of the cross section provided by the third protrusion 19 will decrease, and it will not provide sufficient stiffness. In order to maintain the anti-bulging ability, the protrusion distance of the first protrusion 15 needs to be increased, which will cause the effective space of the receiving cavity 12 to be occupied, the expansion of the cell 30 and the gas generation buffer space to be compressed, the gas discharge resistance in the cell 30 will increase, the DC internal resistance will increase, and the overcurrent capacity of the battery 100 will decrease.

[0168] In one feasible implementation, the ratio of the size of the third protrusion 19 to the size of the housing 10 on the third direction D3 is between 0.007 and 0.014. The value can be 0.007, 0.008, 0.09, 0.01, 0.011, 0.012, 0.013, or 0.014, specifically any of the values ​​listed above, or any value between 0.007 and 0.014. This allows for the formation of a sufficiently long reinforcing region on the third direction D3, significantly reducing large-area bulging deflection, preventing bulging deformation from continuing to propagate to the weld, thereby inhibiting fatigue crack initiation and propagation, and improving the structural stiffness and fatigue strength of the weld area. Simultaneously, it prevents the housing 10 from failing to expand properly, thus avoiding a decrease in the current-carrying capacity of the battery 100.

[0169] If the ratio of the size of the third protrusion 19 to the size of the housing 10 is too small, the height dimension of the third protrusion 19 will be too short relative to the height of the housing 10. Due to insufficient effective height, the third protrusion 19 cannot form sufficient buffer, and the large bulge of the housing 10 can still be transmitted to the surface where the opening 11 is located, resulting in poor reinforcement effect on the weld and easy cracking of the weld.

[0170] If the ratio of the size of the third protrusion 19 to the size of the housing 10 is too large, it will indirectly cause the height dimension of the first protrusion 15 to be too long relative to the height of the housing 10, occupying too much internal space of the cavity 12, reducing the energy density of the battery 100. At the same time, the housing 10 cannot expand properly, and the gas in the cell 30 cannot be discharged in time, resulting in high internal resistance of the cell 30 and reduced current carrying capacity of the battery 100.

[0171] On the third direction D3, the size of the third protrusion 19 is between 0.5mm and 10mm. Specifically, it can be 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm, and the value can be any value between 0.5mm and 10mm. This creates a sufficiently long reinforcing area on the third direction D3, significantly reducing large-area bulging deflection, preventing bulging deformation from continuing to propagate to the weld, thereby inhibiting fatigue crack initiation and propagation, and improving the structural stiffness and fatigue strength of the weld area. At the same time, it prevents the casing 10 from being unable to expand properly, thus avoiding a decrease in the current carrying capacity of the battery 100.

[0172] If the size of the third protrusion 19 is too small, the height dimension of the third protrusion 19 will be too short relative to the height of the shell 10. Due to insufficient effective height, the third protrusion 19 cannot form a sufficient buffer, and the large-area bulging of the shell 10 can still be transmitted to the surface where the opening 11 is located, resulting in poor reinforcement effect on the weld and easy cracking of the weld.

[0173] If the third protrusion 19 is too large, it will indirectly cause the height dimension of the first protrusion 15 to be too long relative to the height of the housing 10, occupying too much internal space of the cavity 12, reducing the energy density of the battery 100. At the same time, the housing 10 cannot expand properly, and the gas in the cell 30 cannot be discharged in time, resulting in high internal resistance of the cell 30 and reduced current carrying capacity of the battery 100.

[0174] In one feasible implementation, refer to Figure 23 As shown, the third protrusion 19 is a continuous structure. The third protrusion 19 extends continuously in the second direction D2 without interruption or gap, forming a continuous reinforcing rib connecting the edge of the large surface of the shell 10. The entire opening 11 obtains a uniform cross-sectional moment of inertia. The bulging stress is evenly distributed along the third protrusion 19 without stress abrupt change points, thus avoiding gaps from becoming fatigue crack sources.

[0175] In another feasible implementation, refer to Figure 24 As shown, in the second direction D2, the third protrusion 19 includes at least two spaced-apart third sub-protrusions 191. A longitudinal expansion channel is formed between adjacent third sub-protrusions 191. Each third sub-protrusion 191 causes the local cross-sectional moment of inertia to be superimposed, providing multiple rigid supports along the entire length of the weld, suppressing the transmission of bulging stress to the weld. When the internal gas pressure rises, the longitudinal expansion channel between adjacent third sub-protrusions 191 preferentially generates elastic bulging, absorbing displacement and preventing the overall bulging from concentrating on the weld end, increasing the expansion space to accommodate gas, and improving the fast charging capability.

[0176] A welded portion 40 is formed at the weld between the cover plate 20 and the shell 10. The laser penetrates circumferentially along the surface of the opening 11, forming a continuously extending welded portion 40. The metal of the welded portion 40 is a cast structure after the molten pool has solidified, and its tensile strength is defined as the weld strength. The weld strength of the welded portion 40 is between 70 MPa and 240 MPa. Specifically, the value can be 70 MPa, 100 MPa, 130 MPa, 160 MPa, 190 MPa, 220 MPa, or 240 MPa. The value can be any value between 70 MPa and 240 MPa. Within this range, the strength of the weld itself matches the stiffness of the first protrusion 15.

[0177] If the welding strength of the welded part 40 is too small, the penetration depth will be too shallow or the weld throat will be insufficient, and the weld itself will become weak and indistinct. Therefore, it is necessary to increase the protrusion length of the first protrusion 15 or the wall thickness of the first inner surface 13. However, this will cause the space of the receiving cavity 12 to be occupied, the expansion and gas generation buffer space of the cell 30 to be compressed, the gas discharge resistance to increase, the DC internal resistance to rise, and the overcurrent capacity of the battery 100 to be damaged.

[0178] If the welding strength of the welding part 40 is too high, the laser power needs to be increased, which increases the heat input. The high temperature zone of the molten pool extends into the shell 10, and the high temperature is conducted to the cell body 34 through the shell wall, which can easily damage the cell 30.

[0179] Silicon content, as a key alloying element in laser welding, directly determines the fluidity of the molten pool and the toughness of the heat-affected zone, and is a common control factor for weld fatigue life and the formability of the shell 10. In one feasible embodiment, the mass content of silicon in the shell 10 is between 0.1% and 0.9%. Specifically, the value can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.9%, and can be any value between 0.1% and 0.9%. Within this range, the silicon content simultaneously satisfies the dual requirements of sufficient molten pool fluidity to form a wide weld throat and sufficient alloy plasticity to allow the shell 10 to expand. This allows the weld fatigue life to reach the design target without additional wall thickness, while maintaining the expansion and venting space of the cavity 12.

[0180] If the mass content of silicon in the shell 10 is too low, the molten pool viscosity will be high, the surface tension will be high, the weld throat width will be narrow and the penetration depth will be uneven. Under tensile-shear alternating stress, the weld is prone to defects such as incomplete fusion and porosity, and fatigue cracks will propagate rapidly along the weld throat.

[0181] Excessive silicon content in the casing 10 reduces fracture toughness. Under internal gas pressure, the casing 10 cannot deform sufficiently to absorb expansion displacement, causing bulging stress to be directly transmitted to the weld. To compensate for low plasticity, the wall thickness or the protrusion distance of the first protrusion 15 needs to be increased, further encroaching on the effective space of the receiving cavity 12; the expansion and gas generation buffer space of the cell 30 is correspondingly reduced, increasing gas discharge resistance, raising DC internal resistance, and impairing the overcurrent capacity of the battery 100.

[0182] In one feasible implementation, the casing 10 is an aluminum-based alloy sheet, formed into a quadrangular prism casing 10 by stamping or deep drawing. The low density of aluminum achieves lightweighting of the battery 100 system, while its high thermal conductivity facilitates thermal management. Specifically, the casing 10 contains aluminum, with an aluminum content between 87% and 99% by mass. This high aluminum content ensures material ductility, preventing necking cracks on the large surfaces of the casing 10 during deep drawing, while maintaining low yield strength. This allows for slight elastic deformation when the battery cell 30 is inserted into the casing, avoiding assembly scratches. However, precisely because of the low yield strength of aluminum, under internal air pressure circulation, the center of the large surface bulges significantly, directly transmitting circumferential tensile stress to the edge weld of the opening 11, leading to fatigue cracks at the weld root.

[0183] Therefore, the mass content of silicon in the shell 10 is limited to between 0.2% and 0.9%. Specifically, the value can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.9%, and can be any value between 0.2% and 0.9%. Silicon forms hard particles in the aluminum matrix, improving the alloy's yield strength and enabling wider weld throats and greater penetration in laser welding. This compensates for the low strength of the aluminum-based shell 10, which leads to easy fatigue cracking of the weld, thus giving the shell 10 sufficient rigidity to suppress bulging while retaining the necessary plasticity to absorb impact energy.

[0184] In one feasible implementation, the shell 10 is a square prism shell 10 formed by deep drawing or stamping of steel-based sheet metal. Steel has a high modulus of elasticity, resulting in higher anti-bulging stiffness than aluminum for the same wall thickness. Specifically, the shell 10 contains steel, with a steel content between 67% and 99% by mass. This high steel content maintains high yield strength, resulting in minimal elastic deformation of the large surfaces of the shell 10 under cyclic air pressure and a significant reduction in peak bulging stress. This naturally reduces the alternating tensile-shear strain amplitude borne by the weld at the edge of the opening 11, minimizing weld fatigue crack formation.

[0185] Therefore, the silicon content in the shell 10 is limited to between 0.1% and 0.5%. Specifically, the value can be 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%, and can be any value between 0.1% and 0.5%, as listed above. Since the substrate already possesses sufficient strength, the silicon content can be reduced to avoid the problems of increased weld pool viscosity and decreased toughness caused by excessive silicon content. Under the premise of ensuring strength with high steel content, low silicon content allows the weld to maintain high impact toughness, preventing cracking under drop or extrusion conditions, while maintaining the necessary ductility of the shell 10.

[0186] In the embodiments provided in this disclosure, reference is made to Figure 25 As shown, a welded portion 40 is formed at the weld between the cover plate 20 and the shell 10. The laser penetrates circumferentially along the surface where the opening 11 is located, forming a continuously extending welded portion 40. The penetration direction of the welded portion 40 is parallel to the third direction D3, and the penetration direction of the weld is perpendicular to the cover plate 20. The weld metal extends continuously along the thickness direction of the cover plate 20. The welded portion 40 penetrates the cover plate 20 in the third direction D3, and the molten pool penetrates the cover plate 20. When gas is generated inside the shell 10, under the expansion load of the gas on the cover plate 20, the circumferential tensile strain of the cover plate 20 has no shear component; the crack needs to propagate along the penetration direction, which has the longest path and the greatest energy consumption, and the weld is not prone to fatigue cracking.

[0187] Furthermore, on the third direction D3, the ratio of the dimension of the welded portion 40 to the thickness of the cover plate 20 is between 1.06 and 2.1. Specifically, the ratio can be 1.06, 1.15, 1.25, 1.35, 1.45, 1.55, 1.65, 1.75, 1.85, 1.95, or 2.1, and can be any value between 0.06 and 2.1. Within this range, the penetration depth is sufficient to form a full penetration weld throat, improving the tensile strength and fatigue life of the weld metal; at the same time, the heat input during welding is within a controllable range and will not have too much impact on the battery cell 30.

[0188] If the ratio of the size of the welded part 40 to the thickness of the cover plate 20 is too small, the penetration depth will be insufficient, the effective bearing area of ​​the weld metal will decrease, and under the circumferential tensile and shear alternating stress generated by cyclic expansion, the stress at the root of the weld will be concentrated, fatigue cracks will rapidly propagate along the unpenetrated area, the weld strength will be low, and it will be prone to cracking.

[0189] If the ratio of the size of the welding part 40 to the thickness of the cover plate 20 is too large, the laser power needs to be increased. The high temperature area of ​​the molten pool extends into the cover plate 20 along the third direction D3 and is conducted into the interior of the housing 10. The heat can easily be directly radiated to the battery cell body 34, causing an internal short circuit.

[0190] In one feasible implementation, the weld portion 40 located at the cover plate 20 is larger than the weld portion 40 located at the shell 10 in the third direction D3. The weld portion 40 has a wedge-shaped cross-section in the third direction D3: the weld width and depth on the cover plate 20 side are greater than those on the flange side of the shell 10. When the internal gas pressure of the shell 10 expands, the cover plate 20 bears the maximum circumferential tensile stress, distributing more weld metal to the cover plate 20 side, allowing the load-bearing section to coincide with the maximum stress zone. The weld pool forms a greater weld depth on the cover plate 20 side, increasing the effective weld throat area, increasing the load-bearing metal per unit perimeter, and making the weld less prone to cracking.

[0191] On the third direction D3, one end of the welded portion 40 extending into the housing 10 is spaced apart from the end of the first protrusion 15 away from the opening 11. The bottom of the welded portion 40 and the bottom of the first protrusion 15 maintain a non-zero distance on the third direction D3, so that the laser molten pool solidifies before reaching the bottom of the first protrusion 15, preventing the strength of the first protrusion 15 from being reduced due to weld penetration. It also avoids weld penetration causing molten pool metal spatter and high-temperature heat-affected zone to affect the cell 30 and induce a short circuit in the cell 30.

[0192] Preferably, on the third direction D3, the distance between the end of the welded portion 40 extending into the receiving cavity 12 and the end of the first protrusion 15 away from the opening 11 is between 0.2mm and 10mm. Specifically, it can be 0.2mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm, and the values ​​can be the aforementioned values ​​or any value between 0.2mm and 10mm. Within this range, both the weld strength and the structural strength of the first protrusion 15 are ensured, while preventing molten metal spatter and the high-temperature heat-affected zone from affecting the battery cell 30.

[0193] If the spacing is too small, the heat can easily damage the battery cell 30. The welding heat will radiate directly to the receiving cavity 12 along the rib root of the first protrusion 15. The high-temperature heat-affected zone will affect the battery cell 30, inducing a short circuit and damaging the battery cell 30. If the spacing is too large, the penetration depth will be shallow, and the effective cross-sectional area of ​​the weld throat will be reduced. The shallow penetration depth of the weld throat is prone to cracking under impact or vibration loads, resulting in poor weld strength.

[0194] In one feasible implementation, on the third direction D3, one end of the welded portion 40 extending into the receiving cavity 12 is spaced apart from the end of the cover plate 20 near the housing 10. The bottom of the welded portion 40 maintains a non-zero distance from the lower surface of the cover plate 20 (i.e., the inner end face of the cover plate 20 near the housing 10), and the bottom of the welded portion 40 extends beyond the lower surface of the cover plate 20. The welded portion 40 has a deeper penetration depth, thereby forming a weld throat with a larger cross-sectional area. The uniformly fully penetrated weld throat provides a continuous load-bearing section. Under impact or vibration loads, the crack propagation path is the longest and the energy consumption is the greatest, which improves the welding quality and thus improves the weld strength.

[0195] Preferably, on the third direction D3, the distance between the end of the welded portion 40 extending into the receiving cavity 12 and the end of the cover plate 20 near the housing 10 is between 0.2mm and 2mm. Specifically, it can be 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, or 2mm, and the values ​​can be the aforementioned values ​​or any value between 0.2mm and 2mm. Within this range, both the weld strength and the structural strength of the first protrusion 15 are ensured, while preventing molten metal splashing and the high-temperature heat-affected zone from affecting the battery cell 30.

[0196] If the spacing is too small, the penetration depth will be shallow, reducing the effective cross-sectional area of ​​the weld throat. Weld throats with shallow penetration depth are prone to cracking under impact or vibration loads, resulting in poor weld strength. If the spacing is too large, the heat can easily damage the battery cell 30. The welding heat will radiate directly to the receiving cavity 12 along the rib root of the first protrusion 15, and the high-temperature heat-affected zone will affect the battery cell 30, inducing a short circuit and damaging the battery cell 30.

[0197] In one feasible implementation, refer to Figure 26 As shown, a welded portion 40 is formed at the weld between the cover plate 20 and the housing 10. The laser welds along the junction of the cover plate 20 and the flange of the housing 10. After the molten pool solidifies, a continuous welded portion 40 is formed. The penetration direction of the welded portion 40 is parallel to the first direction D1. The laser energy is incident perpendicularly to the cover plate 20, and the penetration direction of the molten pool is coaxial with the normal of the large surface of the housing 10. The perpendicular penetration only acts on the local area of ​​the flange, and the cover plate 20 maintains its original flatness. The penetration length of the weld is set to just penetrate the flange without extending into the receiving cavity 12, so as to avoid direct damage to the battery cell 30 when welded through. Even if welded through, because there is a certain gap between the outer wall of the battery cell 30 and the first inner surface 13, the molten pool will not splash onto the battery cell 30, and the heat radiation will not be sufficient to affect the battery cell 30, thus avoiding damage to the battery cell 30.

[0198] Laser welding is performed laterally along the plane of cover plate 20. The molten pool is flat and strip-shaped, with its depth direction parallel to the large surface of cover plate 20. When the internal gas pressure causes the center of cover plate 20 to bulge, the circumferential tensile stress of cover plate 20 directly acts on the longitudinal direction of the molten pool. The weld metal is in a state of tension and shear, lacking the restraining force in the third direction D3, resulting in stress concentration. Fatigue cracks are prone to propagate along the entire length of the molten pool. To ensure weld strength, the limit is 110Ah / mm ≤ A / (x×y×z) ≤ 280000Ah / mm. Specifically, the values ​​can be 110 Ah / mm, 1200 Ah / mm, 1500 Ah / mm, 3000 Ah / mm, 8000 Ah / mm, 10000 Ah / mm, 50000 Ah / mm, 70000 Ah / mm, 100000 Ah / mm, 119050 Ah / mm, 150000 Ah / mm, 200000 Ah / mm, 220000 Ah / mm, 250000 Ah / mm, or 280000 Ah / mm. These values ​​can be the ones listed above or any value between 110 Ah / mm and 280000 Ah / mm. In other words, moderately increasing the protrusion distance or silicon content of the first protrusion 15 increases the local stiffness and the width of the molten pool simultaneously, thereby suppressing fatigue crack initiation and propagation, and improving the structural stiffness and fatigue strength of the weld area.

[0199] Preferably, the size of the welded portion 40 in the first direction D1 is between 0.4mm and 1.3mm. Specifically, it can be 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, or 1.3mm. The value can be one of the values ​​listed above or any value between 0.4mm and 1.3mm.

[0200] If the size of the welded part 40 is too small, the penetration depth will be shallow, reducing the effective cross-sectional area of ​​the weld throat. Weld throats with shallow penetration depth are prone to cracking under impact or vibration loads, resulting in poor weld strength. If the size of the welded part 40 is too large, the heat can easily damage the battery cell 30. The welding heat will directly radiate to the housing cavity 12, and the high-temperature heat-affected zone will affect the battery cell 30, inducing a short circuit and damaging the battery cell 30.

[0201] Furthermore, along the third direction D3, the size of the weld portion 40 located at the shell 10 is larger than the size of the weld portion 40 located at the cover plate 20. Viewed along the third direction D3, the weld line cross-section has a trapezoidal structure, forming an asymmetrical weld throat. The weld width on the cover plate 20 side is smaller, maintaining only a narrow and deep penetration to avoid excessive heat input. The weld width on the flange side of the shell 10 is larger, increasing the local cross-sectional moment of inertia and improving resistance to bulging. When gas bulges inside the shell 10, the circumferential tensile stress first passes through the weld width area, and the stress is dispersed by a large area of ​​metal, improving the shell 10's resistance to deformation, reducing the alternating tensile and shear strain amplitude at the weld, making the weld less prone to fatigue cracking, and preventing fatigue cracking of the weld.

[0202] In the embodiments provided in this disclosure, z satisfies the following relationship: 0.01 ≤ z ≤ 0.6. Specifically, the ratio can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6, and the value can be one of the aforementioned listed values ​​or any value between 0.01 and 0.6.

[0203] If the z-value is too small, the cell 30 will be relatively narrow, and the lateral space reserved on the large surface of the shell 10 will be sufficient. When the cell 30 generates gas in circulation, it will preferentially expand to the large surface of the shell 10. The center deflection of the large surface of the shell 10 will increase, the circumferential tensile stress will be concentrated, the alternating strain amplitude of the welding line will increase, and the weld will be more prone to cracking.

[0204] If the z-value is too large, the overall energy density of the cell will be low, the surface density and compaction density of the electrode will be low, the DC internal resistance will increase, the continuous fast charging current capability will decrease, and the overcurrent performance will be damaged.

[0205] In one feasible embodiment, the second outer surface 32 is spaced apart along the second direction D2, and the second outer surface 32 is opposite to the second inner surface 14. The outer surface of the cell 30 also includes two third outer surfaces 33 spaced apart along the third direction D3. One of the third outer surfaces 33 faces the cover plate 20. The cover plate 20 is provided with a terminal post 50. The cell 30 includes a cell body 34 and a tab 35. The tab 35 is led out from the third outer surface 33 and is electrically connected to the cell body 34 and the terminal post 50 respectively.

[0206] The current path of the tab 35 is not directly facing the large surface (first inner surface 13) of the housing 10. When the cell 30 generates gas, the high-pressure gas flow first rushes towards the channel opposite to the opening 11, avoiding direct vertical impact on the center of the large surface of the housing 10. This slows down the expansion of the housing 10 and prevents the bulging deformation from being concentrated and transmitted to the long side weld between the large surface of the housing 10 and the cover plate 20. This suppresses the initiation and propagation of fatigue cracks and improves the structural stiffness and fatigue strength of the weld area.

[0207] Furthermore, the tab 35 extends from the third outer surface 33 (i.e., the side opposite to the opening 11). The tab 35 extends vertically upward from the third outer surface 33 without any lateral bending. The current vector is coaxial with the normal of the cover plate 20, minimizing the conductive length, reducing the overcurrent path, and increasing the overcurrent capacity of the battery 100. At the same time, the heat from the tab 35 diffuses directly outward through the electrode post 50 of the cover plate 20 without passing through the large surface of the casing 10. The temperature rise in the weld area is reduced, and the heat from the tab 35 is less likely to directly affect the weld. The thermo-mechanical alternating stress amplitude decreases, ensuring the weld strength.

[0208] When the tab 35 is led out from the opening 11, the distance to the output end of the cell 30 can be reduced, thereby shortening the overcurrent transmission path and improving the overcurrent capacity of the battery 100. However, the output end of the cell 30 will generate heat during the cycle, which will affect the weld strength test. At this time, it is limited that 110Ah / mm≤A / (x×y×z)≤300000Ah / mm. Specifically, the values ​​can be 100 Ah / mm, 1200 Ah / mm, 1500 Ah / mm, 3000 Ah / mm, 8000 Ah / mm, 10000 Ah / mm, 50000 Ah / mm, 70000 Ah / mm, 100000 Ah / mm, 119050 Ah / mm, 150000 Ah / mm, 200000 Ah / mm, 220000 Ah / mm, 250000 Ah / mm, or 300000 Ah / mm. These values ​​can be the ones listed above, or any value between 110 Ah / mm and 300000 Ah / mm. This increases the stiffness of the first protrusion 15 and reduces its bulging displacement, thereby offsetting the thermal stress increase brought by the tab 35 and ensuring weld strength.

[0209] In one feasible implementation, on the third direction D3, the shortest distance between the second outer surface 32 and the cover plate 20 is between 1mm and 5mm. Specifically, it can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm, and the value can be any value between 1mm and 5mm, specifically the values ​​listed above. Within this range, the bending length of the tab 35 is the shortest, and the overcurrent resistance does not increase; at the same time, sufficient top clearance is maintained so that gas can reach the pressure relief area of ​​the opening 11 along the top surface gap without accumulating too much gas.

[0210] If the shortest distance between the second outer surface 32 and the cover plate 20 is too small, only a narrow channel remains between the tab 35 and the cover plate 20. When gas is generated inside the housing 10, the gas needs to go around to flow to the opening 11, which increases the local flow resistance and affects the gas discharge inside the cell 30.

[0211] If the shortest distance between the second outer surface 32 and the cover plate 20 is too large, only a narrow channel remains between the tab 35 and the cover plate 20. When gas is generated inside the housing 10, the gas needs to go around to flow to the opening 11, which increases the local flow resistance and affects the gas discharge inside the cell 30.

[0212] In one feasible implementation, in the second direction D2, the ratio of the size of a single tab 35 to the size of the cell 30 is between 0.07 and 0.3. This ratio is the ratio of the width of the tab 35 to the width of the cell body 34, involving the balance between the conductive cross-sectional area and the internal venting space. The ratio can be 0.07, 0.1, 0.14, 0.17, 0.2, 0.24, 0.27, or 0.3, specifically the values ​​listed above, or any value between 0.07 and 0.3. Within this range, the tab 35 has sufficient width to reduce resistance, maintain sufficient current carrying capacity, while retaining a lateral venting channel, allowing gas to directly reach the pressure relief area of ​​the opening 11.

[0213] If the ratio of the size of a single tab 35 to the size of the cell 30 is too small, the tab 35 will be too narrow, reducing the conductive cross-sectional area and causing an increase in current density per unit area. This leads to a simultaneous increase in Joule heating and resistance voltage drop, resulting in excessive temperature rise of the tab 35. Consequently, the output resistance of the cell 30 will be high, reducing the battery's overcurrent capacity. Simultaneously, the high-temperature tab 35 will transfer heat to the weld of the cover plate 20, causing superimposed thermo-mechanical alternating stress, which can easily lead to fatigue cracking of the weld.

[0214] If the ratio of the size of a single tab 35 to the size of the cell 30 is too large, the tab 35 will be too wide, and the base of the tab 35 will occupy too much space. Gas will have to go around to reach the opening 11, which will affect the gas discharge inside the cell 30, increase the DC internal resistance, and reduce the overcurrent capacity of the battery 100.

[0215] In the embodiments provided in this disclosure, the battery cell body 34 includes a plurality of stacked electrode sheets. On a third direction D3, the electrode sheets are spaced apart from the first protrusion 15, and the stacked surface of the electrode sheets and the first protrusion 15 maintain a non-zero distance. The shortest interval between the electrode sheets and the first protrusion 15 is between 0.5mm and 5mm. Specifically, it can be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm. The values ​​can be the aforementioned values ​​or any value between 0.5mm and 5mm.

[0216] If the shortest distance between the electrode and the first protrusion 15 is too small, the electrode will be too close to the first protrusion 15, occupying too much space in the cavity 12. When the electrode expands, it will instantly press against the first protrusion 15 and occupy the remaining gap. The gas will have to go around to flow to the opening 11, which will increase the local flow resistance of the electrode, increase the lithium ion transmission resistance, and increase the DC internal resistance.

[0217] If the shortest distance between the electrode and the first protrusion 15 is too large, the electrode stacking needs to lengthen the bending section of the tab 35 to cross the first protrusion 15, which increases the conductive path, increases the current flow path, and reduces the current flow capacity.

[0218] In one feasible implementation, refer to Figure 27 as well as Figure 28 As shown, the battery cell 30 is a wound battery cell 30. The battery cell body 34 includes an integral horizontal extension section 301 and two arc-shaped connecting sections 302. The horizontal extension section 301 extends along the second direction D2, and the two arc-shaped connecting sections 302 are located at both ends of the horizontal extension section 301. The horizontal extension section 301 is a straight winding area, and the arc-shaped connecting sections 302 at both ends are natural winding corners. The arc-shaped connecting sections 302 can play a role in avoiding collisions when the battery is inserted into the casing. When inserted into the casing, the corner section contacts the small surface of the casing 10 first, forming a guide and preventing the edge of the straight section 362 from scratching the casing wall, thus reducing damage to the separator of the battery cell 30. At the same time, the internal space of the housing 10 is increased. The arc corner of the arc-shaped connecting section 302 and the rounded corner of the small face of the housing 10 form a cavity. This cavity is connected along the third direction D3, becoming an additional gas channel. The straight section 362 maintains a design gap with the large face of the housing 10. When gas is generated, the gas can flow quickly along the cavity to the pressure relief area of ​​the opening 11, which facilitates the discharge of gas inside the cell 30.

[0219] Furthermore, in the second direction D2, the ratio of the size of the arc-shaped connecting segment 302 to the size of the cell 30 ranges from 0.02 to 0.1. The ratio can be 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1, and can specifically be one of the values ​​listed above, or any value between 0.02 and 0.1. Within this range, the length of the arc-shaped connecting segment 302 is sufficient to coaxially fit with the rounded corner of the casing 10, achieving self-centering insertion into the casing; simultaneously, the increase in electrode length at the arc-shaped connecting segment 302 is controllable, preventing excessive lengthening of the lithium-ion diffusion path.

[0220] If the ratio is too small, the arc-shaped connecting section 302 will be too short, resulting in a small corner radius, which will not match the rounded corner of the small facet of the shell 10. The self-centering guiding effect will be weakened, and the edge of the straight section 362 will contact the shell wall first, increasing the resistance to entering the shell.

[0221] If the ratio is too large, the arc-shaped connection section 302 will be too long, the electrode length in the corner area will increase, the diffusion path of lithium ions will lengthen, the DC impedance will increase, and the overcurrent capacity will decrease.

[0222] In one feasible implementation, the size of the arc-shaped connecting segment 302 in the second direction D2 is between 5mm and 20mm. Specifically, it can be 5mm, 7mm, 10mm, 12mm, 15mm, 17mm, or 20mm, and the value can be any value between 5mm and 20mm, as listed above. Within this range, the length of the arc-shaped connecting segment 302 is sufficient to coaxially fit with the rounded corner of the housing 10, achieving self-centering insertion into the housing; at the same time, the increase in electrode length at the arc-shaped connecting segment 302 is controllable, and the lithium-ion diffusion path is not excessively lengthened.

[0223] If the size of the arc-shaped connecting section 302 is too small, the arc-shaped connecting section 302 will be too short, resulting in a small corner radius, which will not match the rounded corner of the small face of the shell 10. The self-centering guiding effect will be weakened, and the edge of the straight section 362 will contact the shell wall first, increasing the resistance to entering the shell.

[0224] If the size of the arc-shaped connection section 302 is too large, the arc-shaped connection section 302 will be too long, the length of the electrode in the corner area will increase, the diffusion path of lithium ions will increase, the DC resistance will increase, and the current carrying capacity will decrease.

[0225] In the embodiments provided in this disclosure, reference is made to Figure 28 As shown, the receiving cavity 12 houses at least two parallel battery cell bodies 34, with multiple arc-shaped connecting sections 302 spaced apart along the first direction D1. Each battery cell body 34 has an arc-shaped connecting section 302 with a circular arc structure at both ends. The arc-shaped connecting sections 302 are arranged in parallel along the first direction D1, forming a gas flow channel in the middle. The channel extends along the third direction D3, increasing the internal space. When gas is generated, the gas from multiple battery cells 30 flows into the gas flow channel and reaches the pressure relief area of ​​the opening 11 along the third direction D3, preventing gas accumulation and thus reducing the gas pressure, decreasing the DC resistance, and increasing the overcurrent capacity of the battery 100.

[0226] In one feasible implementation, the maximum spacing between two adjacent arc-shaped connecting segments 302 in the first direction D1 is between 10mm and 40mm. The maximum spacing between the arc-shaped connecting segments 302 is formed between the vertices of the arc. Specifically, the maximum spacing can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, or 40mm, and the value can be any value between 10mm and 40mm, as listed above. Within this range, it facilitates the insertion of the battery cell 30 into the casing while also creating a sufficiently wide gas flow channel.

[0227] If the maximum spacing between two adjacent arc-shaped connecting sections 302 is too small, the two arc-shaped connecting sections 302 will almost touch, the gas flow channel will be too narrow, the gas will be difficult to discharge in time, resulting in increased gas pressure, increased DC resistance, and decreased overcurrent capacity of battery 100.

[0228] If the maximum distance between two adjacent arc-shaped connecting sections 302 is too large, the ends of the two battery cell bodies 34 will open outward, occupying too much space in the receiving cavity 12, and the battery cell body 34 will easily interfere with the housing 10 when it is inserted into the casing.

[0229] In one feasible implementation, the extension direction of the second outer surface 32 is perpendicular to the extension direction of the surface where the opening 11 is located. The second outer surface 32 serves as the small face of the battery cell 30 and the lead-out surface of the tab 35. The pressure relief end face of the battery cell 30 faces the first inner surface 13 or the second inner surface 14 of the housing 10, rather than the cover plate 20. In this way, when the battery cell 30 generates gas, the airflow flows laterally along the second outer surface 32 toward the side wall opening, rather than perpendicularly toward the cover plate 20. The airflow vector is parallel to the large face of the cover plate 20, and the cover plate 20 no longer bears the positive pressure of the gas. The alternating tensile and shear stress amplitude of the circumferential weld of the cover plate 20 decreases, the strength of the weld increases, and fatigue cracking is less likely to occur.

[0230] Furthermore, the second outer surface 32 is misaligned with the first inner surface 13. The pressure relief end face of the battery cell 30 faces the misaligned sidewall of the small face of the housing 10, rather than the center of the large face of the housing 10. The large face of the housing 10 has the largest area and the smallest moment of inertia, making it prone to bulging under air pressure. The small face of the battery cell 30 (second outer surface 32) and the large face of the housing 10 (first inner surface 13) are not on the same plane, preventing the gas from the battery cell 30 from impacting the large face of the housing 10 when it is discharged. When the battery cell 30 produces gas, the high-pressure airflow impacts the small face of the housing 10. The long-side weld between the large face of the housing 10 and the cover plate 20 only bears simple circumferential tensile stress, without additional air pressure impact. The alternating strain amplitude decreases, and the weld is less prone to fatigue cracking.

[0231] Preferably, the value is limited to 1200 Ah / mm ≤ A / (x×y×z) ≤ 300000 Ah / mm. Specifically, the value can be 1200 Ah / mm, 1500 Ah / mm, 3000 Ah / mm, 8000 Ah / mm, 10000 Ah / mm, 50000 Ah / mm, 70000 Ah / mm, 100000 Ah / mm, 119050 Ah / mm, 150000 Ah / mm, 200000 Ah / mm, 220000 Ah / mm, 250000 Ah / mm, or 300000 Ah / mm. The value can be one of the values ​​listed above, or any value between 1200 Ah / mm and 300000 Ah / mm. The protrusion distance of the first protrusion 15 can be appropriately reduced, the effective space in the cavity 12 is increased, and the cross-sectional area of ​​the gas flow channel between the battery cell 30 and the first protrusion 15 is expanded. In this way, when gas is generated, the gas can flow quickly along the expanded gas flow channel to the pressure relief area of ​​the opening 11, ensuring that there is enough space inside the housing 10 to exhaust gas and that the gas pressure does not accumulate.

[0232] In one feasible implementation, refer to Figure 29 as well as Figure 30 As shown, the battery cell 30 includes a battery cell body 34 and tabs 35. The tabs 35 are electrically connected to the battery cell body 34. There are two tabs 35, and there are also two second outer surfaces 32 of the battery cell 30. The two second outer surfaces 32 are arranged opposite each other along the second direction D2, and the two tabs 35 are respectively connected to the two second outer surfaces 32. The two tabs 35 are a positive tab 35 and a negative tab 35. The positive tab 35 and the negative tab 35 are respectively located on opposite sides of the battery cell body 34 along the second direction D2 or the third direction D3, so that the heat of the tabs 35 is distributed at opposite ends of the battery cell body 34, avoiding single-point heat accumulation. The heat diffuses to the shell 10 simultaneously along both sides, and the temperature rise of the weld area of ​​the opening 11 is uniform, avoiding excessive heat concentration. After the heat is dispersed, the thermo-mechanical alternating stress amplitude of the weld decreases, the strength of the weld increases, and fatigue cracking is less likely to occur.

[0233] Preferably, on the third direction D3, the minimum distance between the tab 35 and the surface where the opening 11 is located is between 4.5mm and 20mm. This minimum distance is the distance from the top of the tab 35 to the flange of the end face where the opening 11 is located, which determines the length of the heat conduction path and the electrical conduction path. Specifically, the minimum distance can be 4.5mm, 7mm, 10mm, 12mm, 15mm, 17mm, or 20mm, and the value can be one of the values ​​listed above, or any value between 4.5mm and 20mm. Within this range, the heat conduction path of the tab 35 is long enough, and the temperature rise of the weld is controllable; at the same time, the bending length of the tab 35 is short, which does not increase the impedance.

[0234] If the minimum distance between the tab 35 and the surface of the opening 11 is too small, the heat generated by the tab 35 can be easily conducted directly along the third direction D3 to the flange of the end face of the opening 11. The temperature rise in the weld area is faster, the thermo-mechanical alternating stress amplitude of the weld is superimposed, and the weld is prone to fatigue cracking.

[0235] If the minimum distance between the tab 35 and the surface where the opening 11 is located is too large, the tab 35 needs to be lengthened and bent to reach the cover plate 20 and the pole 50. The conductive path becomes longer, the DC resistance increases, and the overcurrent capacity of the battery 100 decreases.

[0236] On the third direction D3, the minimum distance between the tab 35 and the first protrusion 15 is between 0.5mm and 4mm. This minimum distance is the distance in the height direction from the top of the tab 35 to the bottom of the first protrusion 15. Specifically, the minimum distance can be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, or 4mm. The value can be one of the values ​​listed above, or any value between 0.5mm and 4mm. Within this range, the heat conduction path of the tab 35 is long enough, and the temperature rise of the weld is controllable; at the same time, the bending length of the tab 35 is short, which does not increase the impedance.

[0237] If the minimum distance between the tab 35 and the first protrusion 15 is too small, the heat generated by the tab 35 can be directly conducted to the first protrusion 15 along the third direction D3, and then to the flange of the end face where the first protrusion 15 is located. The temperature rise in the weld area is faster, and the thermo-mechanical alternating stress amplitude of the weld is superimposed, making the weld prone to fatigue cracking.

[0238] If the minimum distance between the tab 35 and the first protrusion 15 is too large, the tab 35 needs to be lengthened and bent to reach the cover plate 20 and the pole 50. The conductive path becomes longer, the DC resistance increases, and the overcurrent capacity of the battery 100 decreases.

[0239] In the embodiments provided in this disclosure, the cell body 34 includes multiple stacked electrodes. The electrodes are stacked layer by layer along the third direction D3 to form the main body of the cell 30. The tab 35 extends from the top and is connected to the electrodes in the same layer. In the third direction D3, the minimum distance between the tab 35 and the opening 11 is equal to the minimum distance between the electrode and the opening 11. The top of the tab 35 is flush with the top of the electrode stack in the third direction D3, and the distances from both to the flanged end face where the opening 11 is located are the same. The tab 35 has no additional bending section and is in the form of an upright short bridge. The current is transmitted almost in a straight line from the electrode, the tab 35 to the terminal 50, thereby reducing the current path, minimizing the conductive length, reducing the current density per unit area, reducing Joule heat, and improving the current carrying capacity.

[0240] In one feasible implementation, the cell body 34 includes multiple stacked electrodes. In the third direction D3, the minimum distance between the tab 35 and the opening 11 is greater than the minimum distance between the cell body 34 and the opening 11. The top of the tab 35 is further away from the flanged end face where the opening 11 is located than the top of the stacked electrodes, forming an inwardly recessed layout of the tab 35. There is a cavity between the top of the tab 35 and the top end face of the cell body 34. This cavity communicates with the gap between the large surface of the housing 10, forming a direct exhaust channel to the opening 11. When gas is generated inside the housing 10, the gas reaches the pressure relief area where the opening 11 is located directly along this exhaust channel without having to bend around the tab 35. This reduces flow resistance and gas pressure, improving current carrying capacity. At the same time, the tab 35 does not extend upward, and the effective space in the height direction of the receiving cavity 12 is not occupied by the tab 35. The height of a single battery 100 can be reduced accordingly, thereby improving space utilization.

[0241] Preferably, on the third direction D3, the distance between the tab 35 and the cell body 34 is between 1mm and 8mm. Specifically, the distance can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, or 8mm, and can be any value between 1mm and 8mm, as listed above. Within this range, the height of the cavity at the top of the cell body 34 is sufficient for gas to escape, the space in the height direction of the receiving cavity 12 is not encroached upon, and the bending length of the tab 35 is minimized, ensuring the current carrying capacity.

[0242] If the spacing is too small, the top of the tab 35 will be almost flush with the top of the cell body 34, and the effective space in the height direction of the cavity 12 will be too small, thus failing to exhaust gas in a timely and effective manner, resulting in increased local air pressure, increased DC internal resistance, and decreased current carrying capacity.

[0243] If the spacing is too large, the tab 35 needs to be extended and bent to reach the terminal 50 on the cover plate 20. The conductive path becomes longer, the DC resistance increases, and the overcurrent capacity of the battery 100 decreases.

[0244] In one feasible implementation, refer to Figure 30 As shown, the battery 100 includes an adapter 36. One end of the adapter 36 is connected to a tab 35, and the other end is connected to a terminal post 50, forming a conductive series structure. The orthographic projection of the second outer surface 32 in the second direction D2 falls on the adapter 36. The projection of the adapter 36 in the second direction D2 covers a portion of the small facet (second outer surface 32) of the cell 30. The adapter does not completely cover the end face of the lead-out end of the tab 35 of the cell 30, leaving a passage for the gas to escape from the cell 30. When gas is generated, the gas flows along the passage between the tab 35 and the adapter 36 to the opening 11, which facilitates the gas to escape from the cell 30, reduces gas accumulation, lowers the gas pressure, and prevents the DC internal resistance from increasing.

[0245] In one feasible implementation, the battery cell 30 is a laminated battery cell 30, which is formed by alternating stacking of positive electrode plates, negative electrode plates and separators; the stacking direction is parallel to the large surface of the housing 10, and the large surface of the battery cell 30 is set opposite to the large surface of the housing 10. The center of the large surface of the laminated battery cell 30 has a large bulging displacement, which directly acts on the large surface of the housing 10.

[0246] Therefore, the moment of inertia of the first protrusion 15 needs to be increased to effectively intercept the bulging stress on the large surface of the shell 10. This ensures the strength of the weld while avoiding excessive reinforcement that would encroach on space. The limit is 110Ah / mm ≤ A / (x×y×z) ≤ 280000Ah / mm. Specifically, the values ​​can be 110Ah / mm, 1200Ah / mm, 1500Ah / mm, 3000Ah / mm, 8000Ah / mm, 10000Ah / mm, 50000Ah / mm, 70000Ah / mm, 100000Ah / mm, 119050Ah / mm, 150000Ah / mm, 200000Ah / mm, 220000Ah / mm, 250000Ah / mm, or 280000Ah / mm. The values ​​can be the ones listed above or any value between 110Ah / mm and 280000Ah / mm.

[0247] In the embodiments provided in this disclosure, reference is made to Figure 31 As shown, the cover plate 20 includes a cover plate body 21 and a boss 22 provided on the cover plate body 21. The boss 22 extends downward from the cover plate body 21 to form a stepped structure. The boss 22 extends at least partially from the opening 11 into the receiving cavity 12. The boss 22 is inserted into the interior of the housing 10 and contacts the inner side of the flange of the housing 10 to form a mechanical limit, ensuring that the cover plate 20 is flush with the end face where the opening 11 of the housing 10 is located. During laser welding, the molten pool spreads evenly along the side of the boss 22, and the weld throat width is consistent, reducing stress concentration. At the same time, the boss 22 increases the effective thickness of the cover plate 20 in the third direction D3, improves the rigidity of the cover plate 20, and reduces the circumferential deformation of the cover plate 20 when gas is generated inside the housing 10. The alternating strain amplitude at the root of the weld decreases, fatigue cracking is less likely to occur, and the weld strength is improved.

[0248] Preferably, the boss 22 is welded to the housing 10. A continuous weld line is formed between the boss 22 and the flange of the housing 10, firmly connecting the boss 22 and the housing 10. The boss 22 is inserted into the housing 10, increasing the welding contact area; the weld metal forms a continuous metal bridge between the boss 22 and the housing 10, increasing the effective load-bearing cross-sectional area. At the same time, the sidewall of the boss 22 provides additional support for the molten pool, avoiding thermal deformation during welding and improving tensile-shear strength. The alternating strain amplitude at the weld root decreases accordingly, making fatigue cracking less likely and improving weld strength.

[0249] In one feasible implementation, on the third direction D3, the size of the boss 22 is larger than the size of the cover plate body 21. The increased height of the boss 22 increases the contact area with the inner side of the flange of the housing 10, forming a more stable hard limit. The side of the boss 22 forms an additional contact surface with the inner side of the flange of the housing 10. During welding, the molten pool spreads along this contact surface, increasing the weld length, the effective load-bearing cross-sectional area, and the tensile-shear strength of the weld. Simultaneously, the sidewall of the boss 22 provides additional support for the molten pool, preventing thermal deformation during welding and resulting in more stable weld quality.

[0250] Preferably, the difference between the size of the boss 22 and the size of the cover plate body 21 is between 0.1mm and 2mm. Specifically, the interval distance can be 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm, or 2mm, and can be any value between 0.1mm and 2mm, as listed above. Within this range, the step height is moderate, the weld length is sufficient, the weld strength is improved, and the effective space of the accommodating cavity 12 is preserved, allowing gas to escape smoothly.

[0251] If the difference between the size of the boss 22 and the size of the cover plate body 21 is too small, the height of the boss 22 and the cover plate body 21 will be close, and the increase in contact area will be limited; if the weld length is insufficient, the effective load-bearing cross-sectional area will be small, and the improvement in weld strength will be limited.

[0252] If the difference between the dimensions of the boss 22 and the cover plate body 21 is too large, the height of the boss 22 will be significantly higher than that of the cover plate 20. The boss 22 will be inserted too deeply into the housing 10, encroaching on the effective space of the internal cavity 12 of the housing 10, and reducing the gap between the telecommunications body and the top of the housing 10. The gas exhaust channel will be obstructed by the boss 22, leading to increased local gas pressure, increased DC internal resistance, and decreased current carrying capacity.

[0253] In one feasible embodiment, the edge of the boss 22 is chamfered, and the junction of the side and top surface of the boss 22 is processed into a bevel to form a chamfered structure. The chamfered structure makes the side of the boss 22 form a guide bevel. When the cover plate 20 is assembled with the housing 10, the guide bevel can guide the cover plate 20 to slide smoothly into the opening of the housing 10, reducing assembly resistance and facilitating insertion into the housing.

[0254] On the third direction D3, the chamfer size is 0.3-1mm, and the ratio of the chamfer size to the boss 22 size is between 0.3mm and 1mm. Specifically, the ratio can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm, and can be any value between 0.3mm and 1mm. Within this range, the chamfer bevel is long enough to ensure smooth insertion into the shell; at the same time, the remaining boss 22 has sufficient height, resulting in a large weld bearing cross-sectional area and ensuring weld strength.

[0255] If the ratio of the chamfer size to the boss size 22 is too small, the chamfer bevel will be too short, resulting in a weak guiding effect. The side of the boss 22 will still be approximately right angle, and the sharp edge will easily scratch the flange of the shell 10 when it is inserted into the shell, which will easily cause interference.

[0256] If the ratio of the chamfer size to the boss size is too large, the chamfer bevel will be long and gentle, the effective height of the boss 22 will be reduced, the contact area with the flange of the shell 10 will be reduced, the effective load-bearing cross-sectional area of ​​the weld will be insufficient, the weld strength will be poor, and when gas is generated inside the shell 10, the stress concentration factor at the root of the weld will increase under the circumferential tensile stress of the expansion, which will easily lead to fatigue cracking.

[0257] In one feasible implementation, refer to Figure 32 As shown, on the third direction D3, the first protrusion 15 and the opening 11 are spaced apart on their respective surfaces. The top of the first protrusion 15 is lower than the flanged end face of the opening 11, forming an inwardly recessed step structure. The cover plate body 21 abuts against the first protrusion 15, and the lower surface of the cover plate 20 is mechanically limited by the first protrusion 15, resulting in good positioning. During welding, the molten pool spreads evenly along the side of the first protrusion 15, improving the weld strength. The side of the cover plate body 21 away from the first protrusion 15 does not extend into the receiving cavity 12, and the cover plate 20 does not protrude outward, reducing the size of the battery 100 and improving the space utilization of the battery pack.

[0258] Preferably, refer to Figure 33 as well as Figure 34 As shown, on the third direction D3, the surface where the first protrusion 15 and the opening 11 are located is flush, and the cover plate body 21 abuts against the first protrusion 15. The top of the first protrusion 15 is coplanar with the end face of the housing 10, and the lower surface of the cover plate 20 directly presses against the flush end faces of the first protrusion 15 and the housing 10, forming a mechanical limit. This facilitates the welding of the cover plate 20 and the housing 10. During welding, the surfaces of the first protrusion 15 and the housing 10 can be melted simultaneously to form a wide and uniform molten pool with a large weld throat area and high weld strength.

[0259] In one feasible implementation, the side of the first protrusion 15 away from the opening 11 is flush with or further away from the opening 11 on the side of the boss 22 away from the cover body 21. In the third direction D3, the bottom of the first protrusion 15 is at the same height as or deeper into the receiving cavity 12 than the boss 22, thereby reducing the occupation of the internal space of the housing 10 by the boss 22. A large top cavity is also maintained between the battery cell 30 and the boss 22, providing sufficient space for the gas inside the cell 30 to be discharged. When gas is generated, the gas can flow directly to the pressure relief area of ​​the opening 11 along this cavity without bypassing the boss 22, reducing gas pressure accumulation, reducing flow resistance, preventing local gas pressure accumulation, reducing gas pressure, and preventing the DC internal resistance from increasing, thus ensuring the overcurrent capacity of the battery 100.

[0260] In the embodiments provided in this disclosure, reference is made to Figure 35 As shown, the cover plate 20 is provided with a terminal post 50 and / or a pressure relief component 60. The terminal post 50 is used for current output, leading the current generated by the battery cell 30 to the external circuit, and at the same time sending the external charging current back to the battery cell 30. The pressure relief component 60 is used for abnormal venting. Once the internal gas pressure of the housing 10 rises abnormally (overcharging, thermal runaway, etc.), the pressure relief component 60 immediately opens to quickly discharge the high-temperature and high-pressure gas and prevent the housing 10 from rupturing.

[0261] The pole post 50 and the pressure relief component 60 are integrated into the same cover plate 20, with a unified positioning reference, which facilitates assembly. The pole lug 35 can be welded and the pressure relief component 60 can be pre-tightened before entering the housing, avoiding secondary operations within the narrow housing 10 and reducing the risk of assembly damage. The limit is 110Ah / mm ≤ A / (x×y×z) ≤ 300000Ah / mm. Specifically, the values ​​can be 110 Ah / mm, 1200 Ah / mm, 1500 Ah / mm, 3000 Ah / mm, 8000 Ah / mm, 10000 Ah / mm, 50000 Ah / mm, 70000 Ah / mm, 100000 Ah / mm, 119050 Ah / mm, 150000 Ah / mm, 200000 Ah / mm, 220000 Ah / mm, 250000 Ah / mm, 280000 Ah / mm, or 300000 Ah / mm. The values ​​can be the ones listed above or any value between 110 Ah / mm and 300000 Ah / mm.

[0262] In one feasible implementation, the cover plate 20 is provided with one of a pole post 50 and a pressure relief component 60, and the other of the pole post 50 and pressure relief component 60 is provided on the wall of the housing 10 opposite to the cover plate 20. The cover plate 20 retains only one of the functional components, the pole post 50 or the pressure relief component 60, and the other functional component is moved to the wall of the housing 10 opposite to the cover plate 20 (such as the bottom wall), forming a split functional layout. For example, if the cover plate 20 is provided with a pole post 50, then the pressure relief component 60 is provided on the bottom wall; or, if the cover plate 20 is provided with a pressure relief component 60, then the pole post 50 is provided on the bottom wall.

[0263] This reduces the number of openings in the cover plate 20, decreases the metal area occupied by the pole post 50 or pressure relief hole in the cover plate 20, improves the overall strength of the cover plate 20, increases the circumferential moment of inertia of the cover plate 20, and prevents deformation of the cover plate 20. When the internal gas pressure of the shell 10 expands, the central deflection of the cover plate 20 decreases, the circumferential tensile strain decreases, the root of the weld no longer bears additional bending stress due to the warping of the cover plate 20, the alternating strain amplitude decreases, and the weld is less prone to fatigue cracking. At the same time, the pole post 50 or pressure relief component 60 on the opposing wall is far away from the heat-affected zone of the weld of the cover plate 20.

[0264] At this point, the constraint is 110 Ah / mm ≤ A / (x×y×z) ≤ 250000 Ah / mm. Specifically, the values ​​can be 110 Ah / mm, 1200 Ah / mm, 1500 Ah / mm, 3000 Ah / mm, 8000 Ah / mm, 10000 Ah / mm, 50000 Ah / mm, 70000 Ah / mm, 100000 Ah / mm, 119050 Ah / mm, 150000 Ah / mm, 200000 Ah / mm, 220000 Ah / mm, or 250000 Ah / mm. These values ​​can be the ones listed above or any value between 110 Ah / mm and 250000 Ah / mm.

[0265] In one feasible implementation, the cover plate 20 is provided with a terminal post 50, which is a flat, elongated rectangular or elliptical structure. The terminal post 50 has a short side in the first direction D1 and a long side in the second direction D2. In the first direction D1, the maximum dimension of the terminal post 50 is 'a', where 'a' is in mm. In the second direction D2, the maximum dimension of the terminal post 50 is 'e', ​​where 'e' is in mm, and 1 < e / a ≤ 4. The ratio can be 1, 1.5, 2, 2.5, 3, 3.5, or 4, specifically the values ​​listed above, or any value between 1 and 4. Within this range, the long side of the terminal post 50 is sufficiently wide, increasing the current-carrying cross-sectional area and heat dissipation surface simultaneously, thus reducing resistance. At the same time, the cover plate 20 retains sufficient rigidity, ensuring the fatigue life of the weld.

[0266] If the ratio is too small, the long side of the electrode 50 will be too short and the conductive cross-sectional area will be small, resulting in high heat generation during continuous fast charging.

[0267] If the ratio is too large, the long side of the pole post 50 will be too long, filling the width of the cover plate 20. The opening will be too large, causing the moment of inertia of the section of the cover plate 20 to drop sharply, the central deflection to increase, and the cover plate 20 to warp easily when it expands. The strain amplitude at the root of the weld will increase sharply, and the weld will be prone to fatigue cracking.

[0268] In one feasible implementation, the battery cell 30 includes a cell body 34 and tabs 35, with the tabs 35 electrically connected to both the cell body 34 and the terminal post 50. One end of the tab 35 is welded to the electrode plate of the battery cell 30, and the other end is directly welded to the terminal post 50, forming a straight conductive path from the electrode plate to the tab 35 to the terminal post 50. This straight conductive path has no lateral bends or transition blocks, allowing current to flow out along the shortest straight line. This shortens the conductive length, reduces resistance and parasitic inductance simultaneously, lowers DC impedance for the same size, and improves the overcurrent capacity of the battery 100. Simultaneously, the heat generated by the tab 35 is reduced, and the heat-generating area of ​​the tab 35 has less impact on the weld.

[0269] In one feasible implementation, refer to Figure 36 As shown, the cover plate 20 has a through hole 23, which can be formed on the cover plate 20 by stamping. The electrode post 50 is covered by the through hole 23 by welding or riveting. The battery cell 30 includes a tab 35 electrically connected to the electrode post 50, and the tab 35 is at least partially accommodated in the through hole 23. The top of the tab 35 is bent upward and extends directly into the through hole 23, and is welded to the bottom surface of the electrode post 50. At least part of the bent section of the tab 35 is accommodated in the through hole 23, and no longer occupies additional space in the cavity 12 of the housing 10. The net height from the top of the battery cell 30 to the inner surface of the cover plate 20 is increased, the effective space of the cavity 12 is increased, and the increased top space forms an exhaust channel. When gas is generated inside the housing 10, the gas can reach the pressure relief area of ​​the opening 11 directly along the exhaust channel, reducing gas accumulation, preventing the DC internal resistance from increasing, and ensuring the overcurrent capacity of the battery 100.

[0270] For each embodiment and comparative example, a certain number of batteries 100 are taken, and the dimensions x of the first protrusion 15 in the first direction D1, the silicon content y% in the first inner surface, the ratio z of the area of ​​the second outer surface 32 to the area of ​​the first inner surface 13, the capacity A of the battery 100, and the formula value A / (x×y×z) are set according to the table below. Apart from these, all other characteristics of the battery 100 are the same.

[0271]

[0272]

[0273] Analysis of the table above shows that Examples 1 to 34 cover different parameter combinations, demonstrating the performance changes of battery 100 under different design conditions. These examples demonstrate that within the preset parameter range, the battery 100 design can effectively achieve simultaneous improvements in energy density, reliability, and safety. Specifically, referring to Examples 25 to 34, the parameters in these examples are all within a more favorable range, ensuring that the temperature of the terminal 50 remains within a preset reasonable range, providing good fast-charging overcurrent capability, and significantly reducing the risk of cracking in the cover plate 20. Referring to Example 9, although the temperature of the terminal 50 is lower than in Example 5, and the cracking rate at the connection between the cover plate 20 and the casing 10 is smaller, this range is not selected because the battery 100 itself has a very small capacity and therefore has little practical application value.

[0274] Comparative Examples 1 to 5 demonstrate the problems that may result from parameter combinations that exceed the preset range. When the parameter combinations exceed the range, excessive heat is generated inside the battery 100 or the connection between the battery 100 casing 10 and the cover plate 20 fails, affecting the overall performance of the battery 100.

[0275] This disclosure provides a method for testing the temperature rise of the electrode post at 50°C. For each embodiment and comparative example, three batteries 100 of the same model are taken. The A, x, y, and z values ​​of the three batteries 100 are shown in the table above; otherwise, they are identical. The three batteries 100 are then subjected to charge-discharge tests, and the test method is as follows:

[0276] At 25℃, connect terminal 50 to a temperature sensor and charge battery 100 at a constant current rate of 4C until the voltage of battery 100 reaches its upper limit. Then switch to constant voltage charging until the current of battery 100 drops to 0.05C. Record the temperature change of terminal 50 throughout the charging process. If the highest temperature T of terminal 50 is less than or equal to 45℃, the test result is considered good. If the highest temperature T of terminal 50 is greater than 65℃, it is considered unqualified. Calculate the problem of the three batteries 100 and take the average value.

[0277] Different systems require corresponding adjustments to the upper and lower voltage limits: LEP - upper limit voltage 3.65V, lower limit voltage 2.5V; NCM - upper limit voltage 4.25V, lower limit voltage 2.5V; LFMP - upper limit voltage 4.25V, lower limit voltage 2.5V; Lithium nickel manganese oxide - upper limit voltage 4.8V, lower limit voltage 3.5V.

[0278] In this application, specifically, in one feasible embodiment, the present disclosure provides a method for testing the cracking of the casing 10. For different embodiments and comparative examples, 200 batteries 100 of the same model are taken; the 200 batteries 100 are stacked in a large-face-to-large-face manner to form a battery pack, and the 100 batteries 100 are connected in series to form a battery pack. A preload of 3000N is applied to the large-face surface of the two end batteries 100 in the battery pack on the side away from the other batteries 100 in the battery pack. The battery pack is then subjected to charge-discharge cycles for 100 cycles. After the cycle, observe whether there are cracks at the connection between the cover plate 20 of battery 100 and the casing 10 in the battery pack, and record the number of cracks. If the number of cracks in battery 100 is less than or equal to 2%, it is qualified; otherwise, it is unqualified. The conditions for charge-discharge cycle are as follows: under the condition of 25℃, charge battery 100 at a constant current rate of 4C until the voltage of battery 100 reaches the upper limit voltage, then switch to constant voltage charging until the current of battery 100 drops to 0.05C, and then discharge at a rate of 1C until the lower limit voltage is reached.

[0279] Different systems require corresponding adjustments to the upper and lower voltage limits: LEP - upper limit voltage 3.65V, lower limit voltage 2.5V; NCM - upper limit voltage 4.25V, lower limit voltage 2.5V; LFMP - upper limit voltage 4.25V, lower limit voltage 2.5V; Lithium nickel manganese oxide - upper limit voltage 4.8V, lower limit voltage 3.5V.

[0280] This disclosure also provides a method for preparing the battery 100.

[0281] (1) Preparation of the positive electrode:

[0282] The prepared 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 material: conductive agent: binder satisfies (92-98):(4-1):(4-1).

[0283] (2) Preparation of negative electrode:

[0284] The negative electrode active material graphite, 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, 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 graphite: conductive agent: thickener: binder is (90-96): (4-2): (2-1): (4-1).

[0285] (3) Preparation of electrolyte:

[0286] 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 1-2 mol / L.

[0287] (4) Preparation of the diaphragm:

[0288] Polyethylene film is selected as the diaphragm.

[0289] (5) Preparation of lithium-ion battery 100:

[0290] The above-mentioned positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, and then wound or stacked to obtain a bare cell. The bare cell is placed in an outer packaging shell, dried, injected with electrolyte, and then packaged, left to stand, formed, and calibrated to obtain a lithium-ion battery 100.

[0291] 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.

[0292] The negative electrode active material can be selected from one or more of the following: artificial graphite, natural graphite, silicon carbide, silicon oxide, lithium titanate, etc.

[0293] This disclosure also provides a method for testing the dimension x of the first protrusion 15 in the first direction D1. The thickness of the non-protruding position of the first inner surface 13 in the first direction D1 is measured with a micrometer, and the average value is taken as x1. The maximum thickness of the first protrusion 15 in the first direction D1 is measured with a micrometer, and the average value is taken as x2. x = x2 - x1.

[0294] This disclosure also provides a method for testing the mass content y of silicon element in 13 locations on the first inner surface:

[0295] (1) Sample preparation: First, take a 30mm×30mm shell 10 sample, polish the shell 10 sample or clean the shell surface with alcohol to ensure that the sample surface is flat and free of contamination so that X-rays can penetrate and excite fluorescence.

[0296] (2) X-ray excitation: The sample surface is irradiated with high-energy X-rays using a Shimadzu MXF-2400 instrument to excite the characteristic X-ray fluorescence of each element. The wavelength or energy characteristics of these fluorescence spectra correspond to the element types, thus allowing the determination of which elements are contained in the sample.

[0297] (3) Spectral collection and analysis: X-rays reflected from the sample surface and fluorescence spectra emitted are collected using a spectrometer. The type and content of elements can be determined by the position and intensity of characteristic spectral lines; the characteristic wavelength range of silicon is usually 0.713 nm.

[0298] (4) Correction: Repeat steps (2) and (3) to measure 3 samples, take the average value of the 3 samples, and obtain the mass content of silicon element inside shell 10.

[0299] This disclosure also provides a test method for the capacity A of battery 100, wherein battery 100 is placed in a 25°C constant temperature chamber and the following operations are performed on the test object:

[0300] (1) Charge at a constant current rate of 0.33C to the upper limit voltage, and charge at a constant voltage until the current drops to 0.05C;

[0301] (2) Let stand for 30 minutes;

[0302] (3) Discharge at 0.33C to the lower limit voltage;

[0303] Repeat the above steps 3 times, and use the discharge capacity of the third cycle as the battery capacity of 100.

[0304] Different systems require corresponding adjustments to their upper and lower voltage limits: LFP - upper limit voltage 3.65V, lower limit voltage 2.5V; NCM - upper limit voltage 4.25V, lower limit voltage 2.5V; LFMP - upper limit voltage 4.25V, lower limit voltage 2.5V; lithium nickel manganese oxide - upper limit voltage 4.8V, lower limit voltage 3.5V.

[0305] This disclosure also provides a method for testing the ratio z of the area of ​​the second outer surface 32 of the cell 30 to the area of ​​the first outer surface 31.

[0306] The maximum length H of the first outer surface 31 of the battery cell 30 along the third direction D3 and the maximum length L in the second direction D2 are measured using vernier calipers. The area of ​​the first outer surface 31 is calculated using the formula S1=H×L. The maximum length D of the second outer surface 32 of the battery cell 30DE along the second direction D2 is measured using vernier calipers. If the battery cell 30 is a wound battery cell, the area of ​​the second outer surface 32 is calculated using the formula S2=H×D+π(D / 2)2. If the battery cell 30 is a laminated battery cell, the area of ​​the second outer surface 32 is calculated using the formula S2=H×D. The value of z is calculated using the formula z=S2 / S1.

[0307] Based on the battery 100 provided in the above embodiments, in a second aspect, this disclosure also provides a battery pack, including multiple batteries 100 arranged side by side. Preferably, the batteries 100 are arranged side by side along a first direction D1, and the wall containing the first inner surface 13 of any battery 100 is parallel to the wall containing the first inner surface 13 of the adjacent battery 100. The large surfaces of adjacent batteries 100 are parallel to each other and have a consistent spacing, forming a shared constraint gap between the large surfaces of two adjacent batteries 100. When the internal air pressure of any battery 100 increases, causing the large surface of the battery 100 to bulge outward, the large surface of the adjacent battery 100 provides reverse support. The bulging displacement of the large surface of the battery 100 is constrained and attenuated by the adjacent battery 100, thereby limiting the excessive expansion of the battery 100 casing 10, reducing the strength of the circumferential tensile stress transmitted to the weld from the large surface of the battery 100, and causing the alternating strain amplitude of the weld to decrease synchronously, thus improving the strength of the weld and making it less prone to fatigue cracking.

[0308] In one feasible implementation, refer to Figures 37 to 39 As shown, the battery pack includes an energy-absorbing component 70, which is disposed between two adjacent batteries 100. The energy-absorbing component 70 can be made of soft materials such as double-sided tape, silicone rubber, foam, or aerogel, forming a sandwich structure of battery 100-energy-absorbing component 70-battery 100.

[0309] The material of the energy-absorbing component 70 is compressible. When the internal air pressure of any battery 100 increases, causing the battery 100 casing 10 to bulge outward, the energy-absorbing layer is compressed, absorbing the bulging energy, and the bulging displacement is attenuated, resulting in a decrease in the center deflection of the large surface of the battery 100. Simultaneously, the energy-absorbing layer provides reverse support during the rebound phase, preventing the large surface of the opposite battery 100 from being impacted. Furthermore, the soft pad material has a low elastic modulus, preventing the impact force from being directly transmitted to adjacent casings 10, thus preventing localized stress concentration. Because the bulging stress and the mutual impact stress decrease synchronously, the alternating strain amplitude of the weld is reduced, making fatigue cracking less likely.

[0310] In one feasible implementation, refer to Figure 37 As shown, the batteries 100 are arranged along the first direction D1, with multiple batteries 100 placed side by side in a large-to-large-area arrangement. In the first direction D1, the orthographic projections of the first protrusion 15 and the energy-absorbing component 70 on the first inner surface 13 at least partially overlap. There is an overlapping area between the energy-absorbing component 70 and the first protrusion 15. When the energy-absorbing component 70 is compressed, the reverse pressure is transmitted to the first protrusion 15, applying pre-stress to the first protrusion 15. When the large surface of the battery 100 bulges, the cross-sectional moment of inertia of the first protrusion 15 is superimposed with the reverse support, increasing the effective cross-sectional area and preventing the bulging deformation from continuing to be transmitted to the welding line. This inhibits the initiation and propagation of fatigue cracks, improves the structural stiffness and fatigue strength of the area where the welding line is located, and avoids excessive encroachment on the space of the receiving cavity 12.

[0311] In another feasible implementation, refer to Figure 38 As shown, the batteries 100 are arranged along the first direction D1. Multiple batteries 100 are placed side-by-side with their large surfaces facing each other. In the first direction D1, the projections of the first protrusion 15 and the energy-absorbing component 70 onto the first inner surface 13 are offset. There is no overlap between the energy-absorbing component 70 and the first protrusion 15. The wall of the battery 100 directly opposite the energy-absorbing component 70 does not have the first protrusion 15. When the battery 100 expands due to internal inflation, the displacement of the large surface of the battery 100 is absorbed in advance by the energy-absorbing component 70, reducing the deformation in the area where the first protrusion 15 is located. Furthermore, since the first protrusion 15 is not restricted by the energy-absorbing component 70, expansion space is reserved for the first protrusion 15, thus providing some space inside the casing 10 to facilitate the discharge of gas from the battery cell 30.

[0312] In the embodiments provided in this disclosure, reference is made to Figure 39 As shown, multiple energy-absorbing components 70 are arranged at intervals along the third direction D3 between two adjacent batteries 100. Within the gap between the large surface of the housing 10 and the large surface of the housing 10, the energy-absorbing components 70 are divided into multiple segments, arranged at intervals along the third direction D3 (height direction), forming multiple segments. Preferably, two segments of energy-absorbing components 70 are retained within the gap, with the upper segment near the cover plate 20 and the lower segment near the bottom wall, with a gap between the upper and lower segments. This gap in the middle segment corresponds to the largest bulge area at the center of the large surface of the housing 10. When the internal gas pressure of the battery 100 increases, the center of the large surface of the housing 10 can bulge slightly outward, first compressing the upper and lower segments of the energy-absorbing components 70. The gap in the middle provides additional deformation margin, and the overall strain amplitude is absorbed segmentally, providing more expansion space for the housing 10, facilitating the discharge of gas inside the cell 30.

[0313] In one feasible implementation, refer to Figures 40 to 41 As shown, the battery pack includes a heat exchange assembly 80, which is disposed between two adjacent batteries 100. The heat exchange assembly 80 is inserted into the gap between the large surfaces of the housing 10, forming a battery 100-heat exchange assembly 80-battery 100 sandwich structure. The heat exchange assembly 80 can be a cooling plate, thermal conductive gel, heat pipe, etc., and has high thermal conductivity. When the battery 100 expands and generates heat, the heat is quickly conducted to the external environment along the heat exchange assembly 80, rapidly dissipating the internal heat of the battery 100, reducing the temperature rise of the battery 100, and extending cycle life; at the same time, it prevents heat from accumulating inside the battery pack.

[0314] In one feasible implementation, refer to Figure 40As shown, the batteries 100 are arranged along the first direction D1, with multiple batteries 100 placed side by side in a large-to-large-area arrangement. In the first direction D1, the orthographic projections of the first protrusion 15 and the heat exchange assembly 80 on the first inner surface 13 at least partially overlap. Since there is an overlapping area between the heat exchange assembly 80 and the first protrusion 15, when the large surface of the battery 100 bulges, the cross-sectional moment of inertia of the first protrusion 15 superimposes a reverse support, increasing the effective cross-sectional area and preventing the bulging deformation from continuing to propagate to the welding line. This suppresses the initiation and propagation of fatigue cracks, improves the structural stiffness and fatigue strength of the area where the welding line is located, and avoids excessive encroachment on the space of the receiving cavity 12.

[0315] In another feasible implementation, refer to Figure 41 As shown, the batteries 100 are arranged along the first direction D1. Multiple batteries 100 are placed side-by-side with their large surfaces facing each other. In the first direction D1, the projections of the first protrusion 15 and the heat exchange assembly 80 onto the first inner surface 13 are offset. There is no overlap between the heat exchange assembly 80 and the first protrusion 15. The wall of the battery 100 directly opposite the heat exchange assembly 80 does not have the first protrusion 15. When the battery 100 expands due to internal inflation, the deformation of the area where the first protrusion 15 is located is reduced. Furthermore, since the first protrusion 15 is not restricted by the heat exchange assembly 80, expansion space is reserved for the first protrusion 15, thus providing some space inside the casing 10 to facilitate the discharge of gas from the battery cell 30.

[0316] A medium flow channel is formed within the heat exchange component 80 for the flow of cooling medium. In the first direction D1, the dimension of the medium flow channel is m, where m is in mm. m controls the cross-sectional area of ​​the cooling medium flow, and its value ranges from 2 to 8 mm. The ratio of the medium flow channel dimension m to the dimension x of the first protrusion 15 is limited to 2 ≤ m / x ≤ 16. This ratio can be 2, 4, 6, 8, 10, 12, 14, or 16, and can specifically be one of the values ​​listed above, or any value between 2 and 16. Within this range, the ratio of the flow channel dimension to the dimension of the first protrusion 15 is appropriate, ensuring sufficient heat dissipation efficiency while making reasonable use of the internal space of the battery pack.

[0317] If the ratio of the medium flow channel size m to the size x of the first protrusion 15 is too small, the medium flow channel will be too narrow, the cooling medium flow cross-sectional area will be small, the heat exchange efficiency will be low, the battery temperature will rise too high, and the cycle life and fast charging performance will be affected.

[0318] If the ratio of the medium flow channel size m to the size x of the first protrusion 15 is too large, the flow channel will be too wide, the thickness of the heat exchange component 80 will increase, it will occupy too much internal space of the battery pack, the overall volume of the battery pack will increase, and the energy density will decrease.

[0319] In the embodiments provided in this disclosure, A satisfies the following relationship: 80Ah ≤ A ≤ 700Ah, and the value can be 80Ah, 120Ah, 140Ah, 160Ah, 180Ah, 200Ah, 220Ah, 240Ah, 260Ah, 280Ah, 400Ah, 600Ah, or 700Ah. Specifically, the value can be one of the aforementioned listed values, or any value between 80Ah and 700Ah. Within this value range, the capacity of battery 100 is moderate, ensuring both the performance and safety of the individual battery 100, while also preventing fatigue cracking of the weld seams.

[0320] If the value of A is too small, the capacity of a single cell will be too small. In order to achieve the same total capacity, more cells need to be connected in series or parallel when batteries are assembled into a group, which increases the complexity and cost of assembling the group.

[0321] If the value of A is too large, the single cell capacity will be too large, the gas production inside the battery 100 will increase, the bulging stress of the casing 10 will increase, the alternating stress amplitude at the weld will increase, and the weld will be prone to fatigue cracking.

[0322] Furthermore, A is constrained to satisfy the following relationship: 400Ah ≤ A ≤ 700Ah. The value can be 400Ah, 420Ah, 440Ah, 460Ah, 480Ah, 500Ah, 520Ah, 540Ah, 560Ah, 580Ah, 600Ah, 650Ah, or 700Ah. The value can be specifically the values ​​listed above, or any value between 400Ah and 700Ah.

[0323] Thirdly, this disclosure provides an electrical device that may include the aforementioned battery 100 or battery pack. In one feasible embodiment, refer to... Figure 42 As shown, the battery 100 or battery pack is housed within the battery pack 200. The battery pack 200 includes a battery housing and multiple batteries 100. The multiple batteries 100 can be assembled into a battery pack and then installed within the battery housing. Alternatively, the multiple batteries 100 can be directly placed within the battery housing, i.e., there is no need to group the multiple batteries 100 together; the battery housing is used to secure the multiple batteries 100.

[0324] Battery 100 can serve as an operating power source for electrical equipment, or as a driving power source 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.

[0325] In addition, electrical equipment can also be used for the storage, conversion, and release of recyclable electrical energy.

[0326] 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 by, The shell, the cover plate and the battery cell; At least one end of the shell is provided with an opening part, the cover plate seals the opening part and is welded with the shell to form a containing cavity, the shell includes an inner surface close to the containing cavity and an outer surface away from the containing cavity, the inner surface includes two first inner surfaces spaced apart along a first direction and two second inner surfaces spaced apart along a second direction, and a third direction perpendicular to the cover plate, the first direction, the second direction and the third direction are perpendicular to each other, the area of the first inner surface is greater than the area of the second inner surface, at least one of the first inner surfaces is provided with a first protruding part, the first protruding part is protrudingly arranged along the first inner surface in the direction towards the battery cell, and the first protruding part is close to or continuous with the surface where the opening part is located; The battery cell is contained in the containing cavity, the outer surface of the battery cell includes two first outer surfaces spaced apart along the first direction and a second outer surface, the second outer surface forms an opening end of the battery cell, and the area of the first outer surface is greater than the area of the second outer surface; Wherein, the size of the first protruding part in the first direction is x, the unit of x is mm, the mass content of silicon element at the first inner surface is y%, the ratio of the area of the second outer surface of a single battery cell to the area of the first outer surface of the battery cell is z, and the capacity of the battery is A, the unit of A is Ah, wherein, 0.1mm≤x≤1.5mm, 0.1%≤y≤0.9%, 0.01≤z≤0.6, 80Ah≤A≤700Ah, 110Ah / mm≤A / (x×y×z)≤119050Ah / mm.

2. The battery of claim 1, wherein, In the third direction, one end of the first protruding part close to the opening part is flush with the edge of the surface where the opening part is located.

3. The battery of claim 1, wherein, In the third direction, one end of the first protruding part close to the opening part is spaced apart from the surface where the opening part is located.

4. The battery of claim 3, wherein, In the third direction, the distance between one end of the first protruding part close to the opening part and the surface where the opening part is located is between 0.3mm and 2.8mm.

5. The battery of claim 1, wherein, In the third direction, the ratio of the size of the first protruding part to the size of the first inner surface in the direction parallel to the third direction is between 0.0014 and 0.

1.

6. The battery of claim 1, wherein, In the third direction, the size of the first protruding part is between 0.1mm and 15mm.

7. The battery of claim 1, wherein, In the third direction, the first protruding part has a first end and a second end, the first end is closer to the opening part than the second end, the size of the first end in the first direction is greater than the size of the second end in the first direction, and the difference between the sizes is between 0.1mm and 1.3mm.

8. The battery of claim 7, wherein, In the extension direction from the first end to the second end, the size of the first protruding part in the first direction decreases linearly.

9. The battery of claim 1, wherein, In the third direction, the first protruding part includes a first segment and a second segment, the first segment is closer to the opening part than the second segment, and wherein: The minimum size of the first segment in the first direction is greater than the maximum size of the second segment in the first direction. The second segment has a first end and a second end, the first end is connected with the first segment, and the size of the first end in the first direction is greater than the size of the second end in the first direction.

10. The battery of claim 9, wherein, In the third direction, the ratio of the size of the first segment to the size of the second segment is between 1-12.

11. The battery of claim 1, wherein, The shell includes a first wall body opposite to the cover plate in the third direction, and the ratio of the shortest distance between the first protruding part and the surface of the first wall body in the third direction to the size of the shell is between 0.8-0.

98.

12. The battery of claim 1, wherein, The shell includes a first wall body opposite to the cover plate in the third direction, and the first wall body is integrally formed with the wall body where the first inner surface is located, 110Ah / mm≤A / (x×y×z)≤100000Ah / mm.

13. The battery of claim 1, wherein, The shell includes two first wall bodies opposite in the third direction, and the two first wall bodies are provided with the opening part, the cover plate is provided with two, and the cover plate is welded with the corresponding opening part, 1000Ah / mm≤A / (x×y×z)≤35000Ah / mm.

14. The battery of claim 1, wherein, In the second direction, at least one end of the first inner surface is connected with the first protruding part.

15. The battery of claim 1, wherein, In the second direction, at least one end of the first inner surface is spaced apart from the first protruding part.

16. The battery of claim 14, wherein, The interval distance between the end of the first inner surface and the first protruding part is between 0.5mm-5mm.

17. The battery of claim 14, wherein, In the second direction, the first protruding part includes at least two first sub-protruding parts spaced apart.

18. The battery of claim 17, wherein, In the second direction, the interval distance between two adjacent first sub-protruding parts is between 3mm-50mm.

19. The battery of claim 15, wherein, In the second direction, the first protruding part continuously extends.

20. The battery of claim 15, wherein, In the second direction, the first protruding part includes at least two first sub-protruding parts spaced apart.

21. The battery of claim 20, wherein, In the second direction, the interval distance between two adjacent first sub-protruding parts is between 3mm-40mm.

22. The battery of claim 1, wherein, In the second direction, the size of the first protruding part accounts for the size of the shell between 0.8-1.

23. The battery of claim 1, wherein, In the second direction, the size of the first protruding part is between 115mm-600mm.

24. The battery of claim 1, wherein, In the second direction, the first protruding part is arranged in the range of 1 / 3-2 / 3 of the first inner surface, and the size of the first protruding part in the first direction is between 0.3mm-1.5mm.

25. The battery of claim 24, wherein, In the first direction, the wall thickness at the position of the first protruding part is greater than the wall thickness at other positions.

26. The battery of claim 1, wherein, The inner surface of the accommodating cavity further includes a transition surface, the first inner surface and the second inner surface are connected through the transition surface, the transition surface is provided with a protrusion, and the cover plate abuts against the protrusion.

27. The battery of claim 26, wherein, The cover plate is welded with the protrusion.

28. The battery of claim 26, wherein, Adjacent two first inner surfaces and second inner surfaces are connected through the transition surface, and the protrusion is arranged on each transition surface.

29. The battery of claim 26, wherein, The first protruding part is connected with the protrusion.

30. The battery of claim 26, wherein, The first protruding part is spaced apart from the protrusion, and the spacing distance between the first protruding part and the protrusion is between 0.5 mm and 50 mm.

31. The battery of claim 26, wherein, In the first direction, the size of the wall at the position of the protrusion is greater than the size of the wall at the position of the first protruding part.

32. The battery of claim 26, wherein, In the third direction, the minimum distance between the protrusion and the surface where the opening part is located is not less than the minimum distance between the first protruding part and the surface where the opening part is located.

33. The battery of claim 1, wherein, The second inner surface is provided with a second protruding part, which is close to or continuous with the surface where the opening part is located.

34. The battery of claim 33, wherein, 1500 Ah / mm≤A / (x×y×z)≤119050 Ah / mm.

35. The battery of claim 33, wherein, The first protruding part continuously extends along the second direction, and the second protruding part continuously extends along the first direction.

36. The battery of claim 33, wherein, The first protruding part includes at least two first sub-protruding parts spaced apart along the second direction, and the second protruding part includes at least two second sub-protruding parts spaced apart along the first direction.

37. The battery of claim 36, wherein, In the second direction, the spacing distance between two adjacent first sub-protruding parts is between 0.5 mm and 40 mm; and in the first direction, the spacing distance between two adjacent second sub-protruding parts is between 0.5 mm and 20 mm.

38. The battery of claim 33, wherein, In the first direction, the size ratio of the second protruding part to the size of the shell is between 0.62 and 0.

95.

39. The battery of claim 1, wherein, In the first direction, the thickness of the wall where the first protrusion is located is b, the unit of b is mm, wherein 0.05mm 2 ≤x×b≤1mm 2 .

40. The battery of claim 1, wherein, The battery cell includes a battery cell body and a tab, the tab is electrically connected with the battery cell body, and in the first direction, the orthographic projection of the battery cell body on the first inner surface is staggered with the first protruding part.

41. The battery of claim 1, wherein, The battery cell includes a battery cell body and a tab, the tab is electrically connected with the battery cell body, and in the first direction, the orthographic projection of the battery cell body on the first inner surface is at least partially on the first protruding part.

42. The battery of claim 40, wherein, The tab is led to the opening part, wherein 110 Ah / mm≤A / (x×y×z)≤100000 Ah / mm.

43. The battery of claim 40, wherein the battery is a lithium-ion battery. In the first direction, the tab is spaced apart from the first protruding part, and the spacing distance between the tab and the first protruding part is between 0.1 mm and 3.5 mm.

44. The battery of claim 42, wherein the battery is a lithium-ion battery. The battery cell includes a plurality of tabs, the plurality of tabs include positive tabs and negative tabs, the positive tabs and the negative tabs are led to the opening part, and the positive tabs and the negative tabs are arranged along the second direction.

45. The battery of claim 44, wherein, The positive tabs and the negative tabs are spaced apart, and the spacing distance between the positive tabs and the negative tabs is between 30 mm and 270 mm.

46. The battery of claim 40, wherein, The second outer surface is spaced apart along the second direction, the second outer surface is opposite to the second inner surface, the outer surface of the battery cell further includes two third outer surfaces spaced apart along the third direction, and the tab is led from the second outer surface or the third outer surface.

47. The battery of claim 46, wherein, The tab is led from the second outer surface.

48. The battery of claim 46, wherein, The battery comprises a transition piece, the transition piece comprises a vertical segment and a flat segment, the vertical segment is connected with the tab, the flat segment extends towards the opening part, the flat segment is located between the first inner surface and the first outer surface, and the orthogonal projection of the flat segment on the first inner surface at least partially falls on the first protrusion in the first direction.

49. The battery of claim 48, wherein, In the first direction, the flat segment is spaced apart from the first protrusion, and the spacing distance between the flat segment and the first protrusion is between 3mm and 8mm.

50. The battery of claim 46, wherein, 1200 Ah / mm≤A / (x×y×z)≤119050Ah / mm.

51. The battery of any one of claims 1-50, wherein, The outer surface of the shell is provided with a third protrusion, the third protrusion is located on the opposite two surfaces of the first protrusion on the same wall surface of the shell, and the orthogonal projection of the third protrusion on the first inner surface at least partially overlaps with the orthogonal projection of the first protrusion on the first inner surface in the first direction.

52. The battery of claim 51, wherein, In the first direction, the size of the third protrusion is between 0.1mm and 1.5mm.

53. The battery of claim 51, wherein, In the first direction, the ratio of the size of the first protrusion to the size of the third protrusion is between 0.5 and 15.

54. The battery of claim 51, wherein, In the third direction, the ratio of the size of the third protrusion to the size of the shell is between 0.007 and 0.

014.

55. The battery of claim 51, wherein, In the third direction, the size of the third protrusion is between 0.5mm and 10mm.

56. The battery of claim 51, wherein, In the second direction, the third protrusion continuously extends.

57. The battery of claim 51, wherein, In the second direction, the third protrusion comprises at least two third sub-protrusions which are spaced apart.

58. The battery of any one of claims 1-50, wherein, The welding part is formed at the welding position of the cover plate and the shell, and the welding strength of the welding part is between 70Mpa and 240Mpa.

59. The battery of claim 1, wherein, The shell material contains aluminum element, the mass content of aluminum element in the shell is between 87% and 99%, and the mass content of silicon element in the shell is between 0.2% and 0.9%.

60. The battery of claim 1, wherein, The shell material contains steel element, the mass content of steel element in the shell is between 67% and 99%, and the content of silicon element in the shell is between 0.1% and 0.5%.

61. The battery of claim 1, wherein, The welding part is formed at the welding position of the cover plate and the shell, the penetration direction of the welding part is parallel to the third direction, and the welding part penetrates the cover plate in the third direction.

62. The battery of claim 61, wherein, In the third direction, the ratio of the size of the welding part to the thickness of the cover plate is between 1.06 and 2.

1.

63. The battery of claim 61, wherein, In the third direction, the size of the welding part at the cover plate is greater than the size of the welding part at the shell.

64. The battery of claim 61, wherein, In the third direction, one end of the welding part extending into the shell is spaced apart from one end of the first protrusion away from the opening part.

65. The battery of claim 64, wherein, In the third direction, the spacing distance between one end of the welding part extending into the accommodating cavity and one end of the first protrusion away from the opening part is between 0.2mm and 10mm.

66. The battery of claim 61, wherein, In the third direction, one end of the welding part extending into the accommodating cavity is spaced apart from one end of the cover plate close to the shell.

67. The battery of claim 66, wherein, In the third direction, the welding part extends into one end of the accommodating cavity, and the distance between the welding part and the end of the cover plate close to the shell is between 0.2 mm and 2 mm.

68. The battery of claim 1, wherein, The welding part is formed at the welding position of the cover plate and the shell, and the penetration direction of the welding part is parallel to the first direction.

69. The battery of claim 68, wherein, 110 Ah / mm≤A / (x×y×z)≤100000 Ah / mm.

70. The battery of claim 68, wherein, In the first direction, the size of the welding part is between 0.4 mm and 1.3 mm.

71. The battery of claim 68, wherein, In the third direction, the size of the welding part at the shell is greater than the size of the welding part at the cover plate.

72. The battery of claim 1, wherein, The second outer surface is arranged in a second direction, and the second outer surface is opposite to the second inner surface. The outer surface of the battery cell further includes two third outer surfaces arranged in a third direction. One of the third outer surfaces faces the cover plate, and the cover plate is provided with a pole. The battery cell includes a battery cell body and a tab. The tab is drawn from the third outer surface, and the tab is electrically connected to the battery cell body and the pole, respectively.

73. The battery of claim 72, wherein, 110 Ah / mm≤A / (x×y×z)≤100000 Ah / mm.

74. The battery of claim 72, wherein, In the third direction, the shortest distance between the second outer surface and the cover plate is between 1 mm and 5 mm.

75. The battery of claim 72, wherein, In the second direction, the ratio of the size of a single tab to the size of the battery cell is between 0.07 and 0.

3.

76. The battery of claim 72, wherein, The battery cell body includes a plurality of stacked pole pieces. In the third direction, the pole pieces are arranged apart from the first protruding part, and the shortest distance between the pole pieces and the first protruding part is between 0.5 mm and 5 mm.

77. The battery of claim 72, wherein, The battery cell body includes an integral horizontal extension and two arc-shaped connecting segments. The horizontal extension extends in the second direction. In the second direction, the two arc-shaped connecting segments are located at the two ends of the horizontal extension, respectively.

78. The battery of claim 77, wherein, In the second direction, the ratio of the size of the arc-shaped connecting segment to the size of the battery cell ranges from 0.02 to 0.

1.

79. The battery of claim 78, wherein, In the second direction, the size of the arc-shaped connecting segment is between 5 mm and 20 mm.

80. The battery of claim 78, wherein, The accommodating cavity contains at least two parallel arranged battery cell bodies, and a plurality of arc-shaped connecting segments are arranged apart in the first direction.

81. The battery of claim 80, wherein, In the first direction, the maximum distance between adjacent two arc-shaped connecting segments is between 10 mm and 40 mm.

82. The battery of claim 1, wherein, The extension direction of the second outer surface is perpendicular to the extension direction of the surface on which the opening part is located.

83. The battery of claim 82, wherein, The second outer surface is misaligned with the first inner surface.

84. The battery of claim 83, wherein, 1200Ah / mm≤A / (x×y×z)≤119050Ah / mm.

85. The battery of claim 83, wherein, The battery cell includes a battery cell body and a tab. The tab is electrically connected to the battery cell body. Two tabs are provided, and the two tabs are respectively connected to the two second outer surfaces.

86. The battery of claim 85, wherein, In the third direction, the minimum distance between the tab and the surface on which the opening part is located is between 4.5 mm and 20 mm.

87. The battery of claim 85, wherein, In the third direction, the minimum distance between the tab and the first protruding part is between 0.5 mm and 4 mm.

88. The battery of claim 85, wherein, The minimum distance between the tab and the opening portion in the third direction is equal to the minimum distance between the pole piece and the opening portion.

89. The battery of claim 85, wherein, The minimum distance between the tab and the opening portion in the third direction is greater than the minimum distance between the battery core body and the opening portion.

90. The battery of claim 89, wherein, The distance between the tab and the battery core body in the third direction is between 1mm and 8mm.

91. The battery of claim 85, wherein, The battery comprises a connector, one end of the connector is connected to the tab, and the projection of the second outer surface in the second direction falls on the connector.

92. The battery of claim 1, wherein, The battery core is a laminated battery core, and 110Ah / mm≤A / (x×y×z)≤100000Ah / mm.

93. The battery of claim 1, wherein, The cover plate comprises a cover plate body and a boss provided on the cover plate body, and the boss extends at least partially into the accommodating cavity from the opening portion.

94. The battery of claim 93, wherein, The boss is welded to the shell.

95. The battery of claim 93, wherein, In the third direction, the size of the boss is greater than the size of the cover plate body.

96. The battery of claim 93, wherein, The difference between the size of the boss and the size of the cover plate body is between 0.1mm and 2mm.

97. The battery of claim 93, wherein, The edge of the boss is chamfered.

98. The battery of claim 97, wherein, In the third direction, the ratio of the size of the chamfer to the size of the boss is between 0.3mm and 1mm.

99. The battery of claim 93, wherein, In the third direction, the first protruding portion is spaced apart from the surface where the opening portion is located, the cover plate body abuts the first protruding portion, and the side of the cover plate body away from the first protruding portion does not extend into the accommodating cavity.

100. The battery of claim 93, wherein, In the third direction, the first protruding portion is flush with the surface where the opening portion is located, and the cover plate body abuts the first protruding portion.

101. The battery of claim 93, wherein, The side of the first protruding portion away from the opening portion is flush with or further away from the opening portion than the side of the boss away from the cover plate body.

102. The battery of claim 93, wherein, The cover plate is provided with a pole column and / or a pressure relief member.

103. The battery of claim 102, wherein, 110Ah / mm≤A / (x×y×z)≤100000Ah / mm.

104. The battery of claim 1, wherein, One of the pole column and the pressure relief member is provided on the cover plate, and the other of the pole column and the pressure relief member is provided on the wall of the shell opposite to the cover plate.

105. The battery of claim 1, wherein, The cover plate is provided with a pole column, in the first direction, the maximum size of the pole column is a, and in the second direction, the maximum size of the pole column is e, wherein 1 106. The battery of claim 104, wherein, The battery core comprises a battery core body and a tab, and the tab is electrically connected to the battery core body and the pole column.

107. The battery of claim 104, wherein, 110Ah / mm≤A / (x×y×z)≤100000Ah / mm.

108. The battery of claim 104, wherein, The cover plate is provided with a through hole, the pole column covers the through hole, the battery core comprises a tab electrically connected to the pole column, and the tab is at least partially accommodated in the through hole.

109. The battery of claim 1, wherein, 250Ah / mm≤A / (x×y×z)≤119050Ah / mm.

110. A battery pack, comprising: The battery group comprises a plurality of batteries according to any one of claims 1-109, the plurality of batteries are arranged side by side, and a wall body on which the first inner surface of any one of the batteries is located is parallel to a wall body on which the first inner surface of an adjacent battery is located.

111. The battery pack of claim 110, wherein, The battery group comprises an energy absorption assembly arranged between two adjacent batteries.

112. The battery pack of claim 111, wherein, The batteries are arranged along the first direction, and in the first direction, the first protruding portion and the energy absorption assembly on the first inner surface are at least partially overlapped in orthographic projection.

113. The battery pack of claim 111, wherein, The batteries are arranged along the first direction, and in the first direction, the first protruding portion and the energy absorption assembly on the first inner surface are staggered in orthographic projection.

114. The battery pack of claim 111, wherein, A plurality of energy absorption assemblies are arranged along the third direction and are spaced apart between two adjacent batteries.

115. The battery pack of claim 110, wherein, The battery group comprises a heat exchange assembly arranged between two adjacent batteries.

116. The battery pack of claim 115, wherein, The batteries are arranged along the first direction, and in the first direction, the protruding portion and the heat exchange assembly on the first inner surface are at least partially overlapped in orthographic projection.

117. The battery pack of claim 115, wherein, The batteries are arranged along the first direction, and in the first direction, the protruding portion and the heat exchange assembly on the first inner surface are staggered in orthographic projection.

118. The battery pack of claim 116, wherein, A medium flow channel is formed in the heat exchange assembly, and in the first direction, the size of the medium flow channel is m, the unit of m is mm, and 2≤m / x≤16.

119. The battery pack of claim 110, wherein, The A satisfies the following relationship: 400 Ah≤A≤700 Ah.

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