Battery, battery pack and electric equipment

Abstract

The invention provides a battery, a battery pack and electric equipment, the battery comprises a shell, the shell comprises a shell body and a cover body, the shell body and the cover body are welded and connected to define a containing cavity, a welding wire part is formed at the welding position of the cover body and the shell body, the shell is provided with a pressure relief piece, the pressure relief piece is provided with a weak part, the bursting pressure of the weak part is M, the bursting pressure of the bonding wire part is N, and M / N is larger than or equal to 0.08 and smaller than or equal to 0.95. Compared with the prior art, by limiting the ratio of the bursting pressure of the weak part to the bursting pressure of the bonding wire part on the pressure relief piece, the ratio is limited within the preset range, so that after the weak part bursts before the bonding wire part, the bonding wire part cannot be fractured too early, meanwhile, the shell cannot be fractured before the bonding wire part, and thermal runaway is avoided.

Description

Technical Field

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

[0002] In related technologies, batteries generally include an outer casing and a cell assembly housed within it. The outer casing includes a shell and a cover. The cover is welded to the shell, forming a weld line between the cover and the shell. To meet explosion-proof requirements, the shell is also equipped with a pressure relief member. When the internal pressure of the shell reaches a certain level, the pressure relief member can quickly explode, thereby avoiding safety risks to the battery. However, there are cases where the cover explodes from the weld line or the shell before the pressure relief member explodes, causing the gas, electrolyte, and metal chips inside the shell to be ejected, triggering thermal runaway of adjacent batteries. Summary of the Invention

[0003] The present disclosure provides a battery, a battery pack, and an electrical device to solve the problem of battery thermal runaway in the related art.

[0004] In a first aspect, the present disclosure provides a battery, comprising a shell, the shell comprising a shell and a cover, the shell and the cover being welded together to enclose a accommodating cavity, a weld line portion being formed at the weld between the cover and the shell, a pressure relief piece being provided on the shell, the pressure relief piece having a weak portion, the bursting pressure of the weak portion being M, and the bursting pressure of the weld line portion being N, wherein 0.08≤M / N≤0.95.

[0005] In a second aspect, the present disclosure provides a battery pack comprising the aforementioned battery.

[0006] In a third aspect, the present disclosure provides an electrical device comprising the aforementioned battery pack.

[0007] Compared with the prior art, the present invention limits the ratio of the bursting pressure of the weak portion on the pressure relief component to the bursting pressure of the welding line portion, and limits the ratio to a preset range. Therefore, even if the weak portion bursts before the welding line portion, the welding line portion will not rupture prematurely, and the shell will not rupture before the welding line portion, thereby avoiding thermal runaway. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of the structure of a battery provided in one embodiment of the present disclosure.

[0009] Figure 2 yes Figure 1 A schematic structural diagram of the battery shown from another perspective.

[0010] Figure 3 yes Figure 1 Schematic cross-section of the pressure relief member of the battery shown.

[0011] Figure 4 yes Figure 1 Schematic diagram of a partial cross-section of the battery shown.

[0012] Figure 5 yes Figure 1 A schematic cross-sectional view of the housing of the battery shown.

[0013] Figure 6 2 is a schematic cross-sectional view of a battery casing provided in another embodiment of the present disclosure.

[0014] Figure 7 4 is a schematic cross-sectional view of a battery casing provided in yet another embodiment of the present disclosure.

[0015] Description of reference numerals:

[0016] 10 - housing, 101 - housing body, 102 - housing extension, 11 - accommodating cavity, 12 - welding wire portion, 13 - connecting portion, 131 - third step surface, 132 - fourth step surface, 14 - first surface, 15 - first wall, 16 - second wall;

[0017] 20 - cover, 201 - cover body, 202 - cover extension, 21 - connection and fitting portion, 211 - first step surface, 212 - second step surface, 22 - pressure relief hole;

[0018] 30-pressure relief member, 31-weak portion, 311-first groove, 32-opening area, 33-reinforced portion;

[0019] 40- boss, 41- air storage chamber;

[0020] 50-protective parts;

[0021] 60-pole assembly;

[0022] 100-battery. DETAILED DESCRIPTION

[0023] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present disclosure and are not to be construed as limiting the present disclosure.

[0024] In related technologies, a battery generally includes an outer shell and a cell assembly installed in the outer shell. The outer shell includes a shell and a cover. The cover is fixed to the shell by welding. The welding point between the cover and the shell forms a welding line. In order to meet explosion-proof requirements, a pressure relief part is also provided on the outer shell.

[0025] The inventors discovered that if the bursting pressure of the battery's pressure relief part is large, and the bursting pressure of the pressure relief part is close to the bursting pressure of the welding wire, when severe gas production occurs inside the battery, there will be no time to relieve the pressure after the pressure relief part bursts. The welding wire between the shell and the cover cannot withstand the gas pressure inside the battery, causing the cover to burst from the welding wire, and the gas, electrolyte and metal chips in the shell to spray out, causing thermal runaway of the adjacent batteries.

[0026] Based on this, firstly, referring to Figures 1 to 7 As shown, an embodiment of the present disclosure provides a battery 100 to solve the above technical problems. The battery 100 includes a shell, which includes a housing 10 and a cover 20.

[0027] The shell 10 and the cover 20 are welded together to enclose a accommodating cavity 11. The accommodating cavity 11 forms an opening on at least one surface of the shell 10. The battery cell components and electrolyte are accommodated in the accommodating cavity 11 through this opening. The shell 10 not only provides physical space for the battery cell components and electrolytes inside the battery 100, so that the battery can carry out electrochemical reactions of charging / discharging, but also undertakes multiple functions such as protection, sealing, heat dissipation and structural support.

[0028] The shape of the cover 20 is adapted to the opening of the housing 10 and may include circular, square, or rectangular shapes. The cover 20 and the housing 10 are typically connected by welding, riveting, or threading. In the embodiments provided herein, the cover 20 and the housing 10 are welded to close the opening. A weld line 12 is formed at the weld between the cover 20 and the housing 10, providing good sealing and mechanical strength.

[0029] A pressure relief member 30 is also provided on the cover 20. This member is used to safely release pressure when the internal pressure of the battery 100 increases abnormally (e.g., due to internal gas accumulation caused by overcharging, a short circuit, or other malfunction), thereby preventing the battery 100 casing from rupturing or exploding. The pressure relief member 30 has a weak portion 31, which is the location on the pressure relief member 30 most vulnerable to explosion. Once the weak portion 31 ruptures, the gas, electrolyte, and metal shavings within the battery 100 can be safely discharged through the resulting pressure relief channel, thereby preventing explosion or fire caused by pressure buildup.

[0030] The pressure relief member 30 has various types, such as explosion-proof valves, pressure valves, breathable membranes, etc. In the embodiments of the present disclosure, an explosion-proof valve is taken as an example to illustrate the structures of the pressure relief member 30 and the weak part 31. In a feasible implementation manner, the explosion-proof valve is a sheet-like structure, and the weak part 31 is the thinnest area in the sheet-like structure. The first groove 311 can be formed by means of laser or stamping. When the internal pressure of the battery 100 reaches the set bursting pressure, the pressure relief member 30 will rupture at the first groove 311 to form a pressure relief channel, thereby releasing the internal pressure. Those skilled in the art can select different types of pressure relief members 30 according to different design requirements and application scenarios, which are not limited herein.

[0031] In the embodiments provided by the present disclosure, the bursting pressure of the weak part 31 (the pressure threshold for suddenly opening and releasing internal gas or liquid after withstanding a certain pressure) is set as M, and the bursting pressure of the wire bonding part 12 is N. The bursting pressure M of the weak part 31 is less than the bursting pressure N of the wire bonding part 12, that is, M < N. When the internal pressure of the battery 100 rises, the weak part 31 can rupture prior to the wire bonding part 12, thereby releasing the internal pressure. The ratio of the bursting pressure M of the weak part 31 to the bursting pressure N of the wire bonding part 12 also satisfies the following relationship: 0.08 ≤ M / N ≤ 0.95. By reasonably setting the relationship between the bursting pressures of the weak part 31 and the wire bonding part 12 and keeping the ratio between the two within a preset range, it can be ensured that the battery 100 can release pressure orderly when the pressure rises.

[0032] If M / N is too large and exceeds the maximum preset range value, the difference between the bursting pressure M of the weak part 31 and the bursting pressure N of the wire bonding part 12 is very small, and the bursting pressure M of the weak part 31 is very close to the bursting pressure N of the wire bonding part 12. Then, when abnormal gas generation occurs inside the battery 100, the internal pressure of the battery 100 rises rapidly. After the internal pressure of the battery 100 exceeds the bursting pressure M of the weak part 31, it quickly reaches the bursting pressure N of the wire bonding part 12. If the pressure relief channel formed by the weak part 31 cannot discharge gas in time, the battery 100 cannot release enough pressure in time through the weak part 31 when the internal pressure rises, and the pressure may directly act on the wire bonding part 12, resulting in the rupture of the wire bonding part 12, causing the cover 20 to fly out, and making the gas, electrolyte, metal chips, etc. inside the battery 100 spray onto the adjacent battery 100, triggering thermal runaway.

[0033] If the ratio M / N is too small, falling below the minimum preset range, the difference between the burst pressure M of the weak portion 31 and the burst pressure N of the weld portion 12 will be too large. The burst pressure M of the weak portion 31 will be much lower than the burst pressure N of the weld portion 12. The weak portion 31 may rupture before the internal pressure of the battery 100 reaches a dangerous level, releasing internal gas or pressure. This may cause the battery 100 to frequently falsely trigger pressure relief under normal operating conditions, failing to effectively protect the battery 100 structure, reducing safety, and affecting the normal operation of the battery 100. When the internal pressure of the battery 100 abnormally rises, the weak portion 31 will rupture first, but may not be able to effectively release sufficient pressure. If the pressure continues to rise, excessive gas generation inside the battery 100 will prevent the battery 100 from bursting at the weld portion 12. The internal pressure of the battery 100 may exceed the tolerance of the housing 10, resulting in a large-scale explosion from the housing 10. In this case, the explosion is severe and may also trigger thermal runaway of the battery 100.

[0034] In the embodiments provided in this disclosure, reference is made to Figure 2 As shown, the shortest distance L between the weak portion 31 and the weld line portion 12 is 2 mm to 30 mm. The ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line portion 12 satisfies the following relationship: 0.01 ≤ M / (N × L) ≤ 0.4. When the internal pressure of the battery 100 abnormally rises, causing the weak portion 31 to burst, the gas generated within the battery 100 will flow to the pressure relief channel created by the weak portion 31. The smaller the shortest distance L between the weak portion 31 and the weld line portion 12, the greater the impact force of the gas on the weld line portion 12, and the faster the pressure is transferred from the weak portion 31 to the weld line portion 12. The larger the shortest distance L between the weak portion 31 and the weld line portion 12, the smaller the impact force of the gas on the weld line portion 12, and the slower the pressure is transferred from the weak portion 31 to the weld line portion 12. By setting this ratio within a reasonable range, the battery 100 can release pressure in an orderly manner when pressure rises, while also avoiding safety issues caused by proximity or distance.

[0035] If M / (N×L) is too large, exceeding the maximum preset range, and the bursting pressure M of the weak portion 31 and the bursting pressure N of the weld line portion 12 are at preset values, then the shortest distance L between the weak portion 31 and the weld line portion 12 is too small, and the distance between the weak portion 31 and the weld line portion 12 is too close. When the internal pressure of the battery 100 increases, the pressure may be rapidly transferred from the weak portion 31 to the weld line portion 12. Before the weak portion 31 ruptures, the weld line portion 12 may have already felt the excessive pressure. If the pressure cannot be effectively released after the weak portion 31 ruptures, the weld line portion 12 may rupture, causing the cover 20 to fly out and triggering thermal runaway of the adjacent battery 100.

[0036] If M / (N×L) is too small and does not reach the minimum preset range value, when the bursting pressure M of the weak portion 31 and the bursting pressure N of the welding line portion 12 are preset values, the shortest distance L between the weak portion 31 and the welding line portion 12 is too large, and the distance between the weak portion 31 and the welding line portion 12 is too far. When a large amount of gas is generated inside the battery 100, the pressure rises rapidly. Although the weak portion 31 will rupture first, it may not be able to effectively release sufficient pressure. The pressure continues to rise, and the gas production inside the battery 100 is too large. The pressure released when the weak portion 31 ruptures cannot be transmitted to the welding line portion 12 in time, resulting in the cover 20 being unable to open in time for pressure relief. The internal pressure of the battery 100 may exceed the bearing capacity of the shell 10, resulting in a large-scale explosion from the shell 10. At this time, the intensity of the explosion is severe and may also cause thermal runaway of the battery 100.

[0037] In a feasible embodiment, the pressure relief member 30 is provided on the cover body 20. At this time, the distance between the weak portion 31 and the welding line portion 12 is relatively close, and the gas generated in the battery 100 has a greater impact force on the welding line portion 12. The ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the welding line portion 12 satisfies the following relationship: 0.08≤M / N≤0.8.

[0038] By reducing the upper limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12, the difference in bursting pressure between the two is made greater. When a large amount of gas is generated inside the battery 100, the pressure rises rapidly, and the weak portion 31 will rupture earlier to release the pressure as soon as possible, thereby preventing the weld portion 12 from rupturing due to continued pressure increase. Since there is a large margin between the bursting pressure M of the weak portion 31 and the bursting pressure N of the weld portion 12, even if the pressure in the battery 100 continues to rise, it will not reach the bursting pressure N of the weld portion 12 within a certain period of time, thereby improving the welding stability between the cover 20 and the shell 10 and preventing the weld portion 12 from rupturing due to excessive pressure. The bursting pressure M of the weak portion 31 should not be set too small, otherwise it may increase the risk of false triggering. The bursting pressure N of the weld portion 12 should also not be set too large, so that the weld portion 12 ruptures before the shell 10.

[0039] Reference Figure 5 as well as Figure 6 As shown, the cover 20 is provided with a pressure relief hole 22. This is an opening in the cover 20 that provides a channel for releasing pressure when the internal pressure of the battery 100 increases. A pressure relief member 30 is provided to cover the pressure relief hole 22 and is welded to the cover 20. When the internal pressure reaches the burst pressure of the weak portion 31 of the pressure relief member 30, the weak portion 31 ruptures, thereby opening the pressure relief hole 22 and releasing pressure, preventing further pressure increase and causing more serious structural damage.

[0040] In another feasible embodiment, the pressure relief member 30 is disposed on the surface of the housing 10 facing the cover 20. In this case, the distance between the weak portion 31 and the weld portion 12 is greater, resulting in slower pressure transmission. Gas generation within the battery 100 has less impact on the weld portion 12, and pressure may not be released promptly. Therefore, the ratio of the burst pressure M of the weak portion 31 to the burst pressure N of the weld portion 12 satisfies the following relationship: 0.3 ≤ M / N ≤ 0.95.

[0041] By increasing the lower limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the welding line portion 12, the difference in the bursting pressures between the two is reduced. When a large amount of gas is generated inside the battery 100, the pressure rises rapidly, and the weak portion 31 ruptures first. The gas in the battery 100 is guided toward the weak portion 31 by the pressure relief channel generated by the rupture of the weak portion 31 and gathered there. Since the weak portion 31 is far away from the welding line portion 12, the welding line portion 12 is less impacted by the gas pressure, while the shell 10 is impacted by the gas. It will be more direct and greater. If the internal air pressure of the battery 100 rises abnormally, the pressure relief member 30 can no longer complete the pressure relief normally. If the bursting pressure N of the welding wire portion 12 is significantly different from the bursting pressure M of the weak portion 31, the shell 10 may burst before the welding wire portion 12. By having a smaller margin between the bursting pressure M of the weak portion 31 and the bursting pressure N of the welding wire portion 12, when the pressure of the battery 100 continues to increase, the welding wire portion 12 will burst earlier than the shell 10 after the weak portion 31 bursts.

[0042] The pressure relief member 30 can be integrally connected to the outer shell. The pressure relief member 30 and the outer shell (such as the cover body 20 or the shell 10) are designed as a whole. There is no separate connection link, so no additional welding or assembly steps are required, which reduces the assembly steps and time and improves the overall assembly efficiency.

[0043] The pressure relief member 30 can also be provided separately from the outer shell. The shell 10 is provided with a through hole, and the pressure relief member covers the through hole and is welded to the shell 10. Since the pressure relief member 30 is an independent component, even if the outer shell is deformed, the structural strength and function of the pressure relief member 30 may not be greatly affected, thereby improving the safety and reliability of the battery.

[0044] The shell can be made of steel, aluminum or metal composite materials. The choice of different materials will affect the bursting pressure M of the weak part 31 and the bursting pressure N of the welding line part 12. Therefore, in actual application, it is necessary to adjust according to the material properties.

[0045] When the housing is made of steel, the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line 12 satisfies the following relationship: 0.15 ≤ M / N ≤ 0.95. Due to the high strength of steel, the overall housing is more robust, less susceptible to deformation or cracking, and less susceptible to bursting from the weld line 12. Therefore, the lower limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line 12 can be narrowed, increasing the lower limit to reduce the difference in bursting pressures. This allows the bursting pressure M of the weak portion 31 to be closer to the bursting pressure N of the weld line 12, allowing the weak portion 31 to rupture preferentially when pressure increases. Furthermore, due to the high strength of the housing 10, a smaller margin can be maintained between the bursting pressure M of the weak portion 31 and the bursting pressure N of the weld line 12, preventing premature rupture of the weld line 12.

[0046] When the outer shell is made of aluminum, the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12 satisfies the following relationship: 0.4 ≤ M / N ≤ 0.95. Because aluminum is weak and the outer shell is more susceptible to deformation, the range of the ratio can be narrowed by increasing the lower limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12. This reduces the difference in bursting pressures between the two, allowing the bursting pressure M of the weak portion 31 to be closer to the bursting pressure N of the weld portion 12. When a large amount of gas is generated within the battery 100, the pressure rises rapidly, causing the weak portion 31 to burst earlier, thereby reducing the pulling force on the weld portion 12. Although the weak portion 31 ruptures first, it may not be able to effectively release sufficient pressure. If the pressure continues to rise, excessive gas production within the battery 100 will occur, and the weld portion 12 will also burst in time, preventing a large-scale explosion from the outer shell 10.

[0047] The shell can be a cylindrical structure, a quadrangular prism structure or a soft-pack structure. The shape of the battery 100 shell will affect the bursting pressure M of the weak part 31 and the bursting pressure N of the welding wire part 12. Therefore, in actual application, it can be adjusted according to the shape of the battery 100 shell.

[0048] When the outer shell is cylindrical, the ratio of the burst pressure M of the weak portion 31 to the burst pressure N of the weld portion 12 satisfies the following relationship: 0.08 ≤ M / N ≤ 0.75. When internal pressure increases, the cylindrical structure experiences relatively little radial expansion, with the force primarily concentrated in the axial direction. Consequently, the tensile force on the weld portion 12 is relatively small. Furthermore, due to the symmetry of the cylindrical structure, the pressure distribution is relatively uniform, resulting in less pressure on the circumference, allowing the shell 10 to withstand greater pressure. Therefore, the burst pressures M and N of the weak portion 31 and weld portion 12 can be appropriately adjusted, reducing the upper limit of the ratio to increase the difference in burst pressure. When a large amount of gas is generated within the battery 100, the pressure rapidly increases. By properly designing the burst pressure ratio, the weak portion 31 ruptures first to release the pressure, and the weld portion 12 ruptures before the shell 10.

[0049] When the outer shell has a quadrangular prism structure, the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12 satisfies the following relationship: 0.08≤M / N≤0.75. When the internal pressure of the quadrangular prism structure increases, it expands relatively significantly, especially at the corners and sides. The tensile force on the weld portion 12 is also relatively large, which can easily cause the weld portion 12 to rupture. To ensure that the weld portion 12 is not torn apart when pressure increases, it is necessary to reduce the upper limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12. This can appropriately increase the strength of the weld portion 12 while reducing the bursting pressure M of the weak portion 31. This will increase the difference in bursting pressure between the two, ensuring that the weak portion 31 ruptures first to achieve pressure relief.

[0050] In the embodiments provided in this disclosure, reference is made to Figure 3 As shown, the surface of the housing on which the weak portion 31 is provided is the first surface 14. The dimension of the weak portion 31 along the length direction of the first surface 14 is greater than the dimension along the width direction of the first surface 14. This makes the weak portion 31 have an elongated or elliptical structure, which is more likely to rupture along the length direction of the weak portion 31 when subjected to force, thereby providing a larger pressure relief area, ensuring that pressure can be quickly released in abnormal situations and avoiding thermal runaway.

[0051] Reference Figure 3As shown, the pressure relief member 30 is a thin sheet structure, and the weak portion 31 is a first groove 311 formed indented on the pressure relief member 30. When the internal pressure increases, the presence of the first groove 311 makes the weak portion 31 the preferred path for pressure release. When the pressure reaches a certain threshold, the weak portion 31 preferentially ruptures to form a pressure relief channel at the first groove 311, thereby guiding the pressure to be released through a preset path. The first groove 311 can be formed by laser etching or stamping, and the longitudinal cross-section of the first groove 311 can be a rectangular, triangular, trapezoidal or U-shaped structure, which is not limited here.

[0052] The depth t of the first groove 311 is 0.01-0.1 mm, and the thickness T of the pressure relief member 30 is 0.15-0.4 mm. The ratio of the depth t of the first groove 311 to the thickness T of the pressure relief member 30 satisfies the following relationship: 0.05≤t / T≤0.6. Adjusting this ratio allows for more controlled pressure relief from the pressure relief member 30, enabling timely pressure relief and preventing housing rupture or explosion. It also prevents the first groove 311 from being too deep, which could lead to insufficient overall strength of the pressure relief member 30 and potentially cause rupture or other structural problems in the weak portion 31 under normal use.

[0053] If the ratio of the groove depth t of the first groove 311 to the thickness T of the pressure relief member 30 is too large, exceeding the maximum preset range value, the groove depth of the first groove 311 is larger or the thickness of the pressure relief member 30 is smaller, which will cause the pressure relief member 30 to explode more easily. The weak portion 31 will rupture before the internal pressure of the battery 100 reaches a dangerous level, releasing internal gas or pressure, causing the battery 100 to frequently falsely trigger the pressure relief under normal working conditions, failing to effectively protect the battery 100 structure, reducing safety, and affecting the normal operation of the battery 100.

[0054] If the ratio of the groove depth t of the first groove 311 to the thickness T of the pressure relief member 30 is too small, falling below the minimum preset range, then the groove depth of the first groove 311 is too small or the thickness of the pressure relief member 30 is too large, resulting in a higher burst pressure M of the weak portion 31 and preventing it from rupturing preferentially when pressure increases. This can result in delayed pressure release. Furthermore, if the difference between the burst pressure M of the weak portion 31 and the burst pressure N of the weld line portion 12 is minimal, with the burst pressure M of the weak portion 31 being very close to the burst pressure N of the weld line portion 12, then when gas is generated within the battery 100, the internal pressure, after exceeding the burst pressure M of the weak portion 31, quickly reaches the burst pressure N of the weld line portion 12. This pressure directly acts on the weld line portion 12, causing it to rupture and eject the cover 20. This can then cause gas, electrolyte, metal shavings, etc. within the battery 100 to spray onto adjacent batteries 100, triggering thermal runaway.

[0055] The first groove 311 is provided on a surface of the pressure relief member 30 facing away from the accommodating chamber 11 or on a surface facing the accommodating chamber 11 .

[0056] The first groove 311 faces away from the surface of the accommodating cavity 11. Specifically, the first groove 311 is located on the outer surface of the pressure relief member 30. Under normal operating conditions, the pressure inside the battery 100 primarily acts on the inner surface of the accommodating cavity 11. Placing the first groove 311 on a surface facing away from the accommodating cavity 11 prevents the weak portion 31 from being directly affected by internal pressure, thereby reducing the risk of abnormal explosion due to unexpected force.

[0057] The first groove 311 is arranged toward the surface of the accommodating cavity 11, that is, the first groove 311 is arranged on the inner surface of the pressure relief member 30. When the internal pressure of the battery 100 increases, the pressure will directly act on the weak portion 31 where the first groove 311 is located, causing it to rupture quickly, thereby achieving rapid pressure relief, ensuring that when the pressure rises abnormally, the battery 100 can release the pressure in time to avoid explosion or structural damage caused by excessive pressure.

[0058] One feasible embodiment further includes a second groove (not shown), with the first groove 311 and the second groove respectively disposed on opposing surfaces of the pressure relief member 30. This provides pressure relief when pressure is applied from different directions. The first groove 311 and the second groove can rupture simultaneously or separately, thereby providing a larger pressure relief area and further improving pressure relief efficiency. Furthermore, by disposing the first groove 311 and the second groove on opposing surfaces, the pressure acting on the pressure relief member 30 can be dispersed, preventing structural damage caused by excessive localized force.

[0059] Further, refer to Figure 2 As shown, the first groove 311 is surrounded by an opening area 32. The shape of the opening area 32 can be circular, elliptical, runway-shaped, rectangular or polygonal, etc., which is not limited here. The opening area 32 is preferably a runway-shaped structure. The runway-shaped opening area 32 has a uniform pressure distribution, which can effectively reduce stress concentration and make the blasting pressure more uniform. The area of ​​the opening area 32 is s, which satisfies the following relationship: 80mm 2 ≤s≤1200mm 2 By controlling the area s of the opening region 32 within a preset range, the weak portion 31 can be promptly ruptured when the internal pressure of the battery 100 increases, releasing the internal pressure and protecting the battery 100 structure. This prevents the welding wire portion 12 from rupturing or the shell 10 from exploding due to excessive pressure. Furthermore, under normal operating conditions, the weak portion 31 will not erroneously trigger pressure relief due to normal pressure fluctuations, thus ensuring the normal operation of the battery 100.

[0060] If the area s of the opening region 32 is too small and does not reach the minimum preset range value, the bursting pressure of the weak portion 31 will be too high, which may result in the weak portion 31 not rupturing in time before the pressure reaches a dangerous level, thereby reducing safety. It may also cause the welding wire portion 12 to rupture soon after the weak portion 31 explodes, causing the cover 20 to fly out, and the gas, electrolyte, metal chips, etc. in the battery 100 to be sprayed onto adjacent batteries 100, causing thermal runaway.

[0061] If the area s of the opening region 32 is too large, exceeding the maximum preset range value, the bursting pressure of the weak portion 31 will be too low, and the weak portion 31 will easily rupture before the internal pressure of the battery 100 reaches a dangerous level, causing leakage of gas or electrolyte inside the battery 100, which will not only reduce the performance and life of the battery 100, but may also cause safety problems such as short circuit and corrosion.

[0062] Further, refer to Figure 2 As shown, a reinforcement portion 33 is formed within the opening region 32. The bursting pressure M of the weak portion 31 and the bursting pressure N of the weld line portion 12 satisfy the following relationship: 0.08 ≤ M / N ≤ 0.65. The reinforcement portion 33 can take various forms, including annular reinforcement ribs, localized reinforcement ribs, or grid-like reinforcement ribs, without limitation. The reinforcement portion 33 can disperse stress, reduce stress concentration points, and prevent premature rupture caused by excessive localized stress. Furthermore, the reinforcement portion 33 enhances the structural strength of the opening region 32, thereby increasing the bursting pressure M of the weak portion 31. This allows the weak portion 31 to withstand higher pressures under normal operating conditions, while ensuring that the weak portion 31 ruptures preferentially when pressure reaches a dangerous level.

[0063] By reducing the upper limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12, the difference in bursting pressure between the two is made greater. When a large amount of gas is generated inside the battery 100, the pressure rises rapidly, and the weak portion 31 ruptures earlier than the weld portion 12. Since the difference between the bursting pressure M of the weak portion 31 and the bursting pressure N of the weld portion 12 is greater, the weld portion 12 can still withstand greater pressure after the weak portion 31 ruptures, thereby improving the welding stability between the cover body 20 and the shell 10 and avoiding rupture of the weld portion 12 due to excessive pressure.

[0064] The reinforcing portion 33 is spaced apart from the weak portion 31, maintaining a certain distance, and this spacing distance is preferably 0.3mm-4mm. If the reinforcing portion 33 is too close to the weak portion 31, it may generate additional force on the weak portion 31 when the battery is working normally or is subjected to external pressure, causing the weak portion 31 to deform or rupture prematurely. If the reinforcing portion 33 is too far away from the weak portion 31, the reinforcement effect may not be significant, and the overall structural strength of the pressure relief member 30 cannot be effectively improved. By controlling this spacing distance within a preset range, it can be ensured that the reinforcing portion 33 will not have an adverse effect on the weak portion 31, thereby ensuring that the weak portion 31 can rupture normally when needed to achieve the pressure relief function, and at the same time, it can ensure the reinforcing effect of the reinforcing portion 33 on the weak portion 31 without affecting the normal function of the weak portion 31.

[0065] In the embodiments provided in this disclosure, reference is made to Figure 4 As shown, the housing also includes a protective member 50 that covers the opening area 32. The protective member 50 forms a protective area above or around the pressure relief member 30, effectively preventing foreign matter such as electrolyte, metal shavings, and water from directly contacting the pressure relief member 30 and preventing the pressure relief member 30 from abnormally exploding. This not only improves the safety and reliability of the battery 100, but also extends the service life of the battery 100. The protective member 50 can be made of PET, PP, etc.

[0066] In a feasible implementation, referring to Figure 4 As shown, a boss 40 is provided on the surface of the shell, and an air storage chamber 41 is formed in the boss 40. The cross-sectional shape of the air storage chamber 41 can be circular, rectangular, polygonal or irregular, etc., which is not limited here. The air storage chamber 41 has a first end and a second end. The first end of the air storage chamber 41 is connected to the accommodating chamber 11 to ensure that the gas generated by the accommodating chamber 11 can smoothly enter the air storage chamber 41. The second end of the air storage chamber 41 forms an opening on the boss 40, and the pressure relief member 30 covers the opening to ensure that the gas can be discharged through the pressure relief member 30.

[0067] The gas storage chamber 41 can increase the gas production space at the pressure relief piece 30 inside the battery 100, so that the gas can explode in a concentrated manner in the pressure relief piece 30. When a large amount of gas is generated inside the battery 100 and the pressure rises rapidly, after the weak part 31 of the pressure relief piece 30 explodes, the gas storage chamber 41 forms a low-pressure area. Since the gas always flows from the high-pressure area to the low-pressure area, the low-pressure area of ​​the gas storage chamber 41 can quickly attract the surrounding gas to gather inside the gas storage chamber 41, so that the airflow can quickly converge to the gas storage chamber 41 and be discharged to the outside of the shell 10 through the weak part 31 under the guidance of the gas storage chamber 41, instead of randomly diffusing to other areas, thereby reducing the impact of the gas on the welding line part 12, and can reduce the risk of the battery 100 exploding from the welding line part 12, and avoid damage to the strength of the welding line part 12 of the cover body 20 and the shell 10.

[0068] Reference Figure 4 As shown, the distance b between the surface where the boss 40 is located and the bottom surface of the first groove 311 satisfies the following relationship: 0.1mm≤b≤0.6mm. The larger the distance b between the surface where the boss 40 is located and the bottom surface of the first groove 311, the larger the volume of the gas storage chamber 41. A larger gas storage chamber 41 can accommodate more gas, providing a larger buffer space, so that the gas can be concentrated at the pressure relief member 30, reducing the impact of the gas on the welding line portion 12. The smaller the distance b between the surface where the boss 40 is located and the bottom surface of the first groove 311, the smaller the volume of the gas storage chamber 41. A smaller gas storage chamber 41 can reduce space occupancy. By regulating this distance within a reasonable range, it can be ensured that the gas storage chamber 41 has an appropriate volume, which can provide sufficient buffer space without taking up too much space.

[0069] Preferably, the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line portion 12 satisfies the following relationship: 0.4 ≤ M / N ≤ 0.95. By increasing the lower limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line portion 12, the difference in bursting pressures between the two is reduced, resulting in a relatively higher bursting pressure M of the weak portion 31 or a relatively lower bursting pressure N of the weld line portion 12.

[0070] When a large amount of gas is generated inside the battery 100, the pressure rises rapidly and the weak portion 31 ruptures first. Since the bursting pressure M of the weak portion 31 is relatively large, this means that the weak portion 31 will only rupture under a higher pressure, thereby ensuring that the pressure relief will not be accidentally triggered under normal working conditions.

[0071] After the weak portion 31 of the pressure relief member 30 explodes, a low-pressure area is formed in the gas storage chamber 41, and most of the gas is guided by the gas storage chamber 41. The pulling force on the welding wire portion 12 is relatively small. By reducing the bursting pressure N of the welding wire portion 12, in extreme cases, the welding wire portion 12 can respond quickly after the weak portion 31 ruptures, thereby avoiding large-scale explosion of the shell 10, thereby protecting the overall structure of the battery 100.

[0072] In the embodiments provided in this disclosure, reference is made to Figures 5 to 7 As shown, the housing 10 has a connecting portion 13 at the opening, and the cover 20 has a connecting and mating portion 21. The connecting portion 13 and the connecting and mating portion 21 are connected by welding, and the welding line portion 12 is formed between the connecting portion 13 and the connecting and mating portion 21. The connecting portion 13 and / or the connecting and mating portion 21 are provided with a step structure. The step structure can be provided on the connecting portion 13 or the connecting and mating portion 21, or both. The provision of the step structure can increase the contact area between the cover 20 and the housing 10, thereby improving the welding strength.

[0073] In a feasible implementation, referring to Figure 5As shown, the step structure includes a first step, which is formed at the connecting and fitting portion 21 of the cover body 20. The thickness of the cover body 20 is increased. The cover body 20 includes a cover body main body part 201 and a cover body extension part 202 protruding at the center of the cover body main body part 201. The step is formed between the cover body main body part 201 and the cover body extension part 202. The first step is a single-stage structure, including a first step surface 211 and a second step surface 212. The first step surface 211 is formed on the bottom surface of the cover body main body part 201, and the second step surface 212 is formed on the side of the cover body extension part 202. When the cover body 20 is connected and assembled with the shell 10, the first step surface 211 is pressed against the surface of the shell 10 to ensure close contact between the cover body 20 and the shell 10. The cover body extension part 202 extends into the accommodating cavity 11, and the second step surface 212 is in contact with the side of the accommodating cavity 11, increasing the contact area between the cover body 20 and the shell 10, thereby improving the welding strength.

[0074] In another feasible embodiment, referring to Figure 6 As shown, the step structure includes a second step, which is formed at the connecting portion 13 of the shell 10. The shell 10 includes a shell body portion 101 and a shell extension portion 102 protruding from the edge of the shell body portion 101. The step is formed between the cover body portion 201 and the cover extension portion 202. The second step is a single-stage structure, including a third step surface 131 and a fourth step surface 132. The third step surface 131 is formed on the top surface of the shell body portion 101, and the fourth step surface 132 is formed on the side of the shell extension portion 102. When the cover body 20 is connected and assembled with the shell 10, the bottom surface of the cover body 20 is pressed against the third step surface 131 to ensure close contact between the cover body 20 and the shell 10. The side surface of the cover body 20 is in contact with the fourth step surface 132, which increases the contact area between the cover body 20 and the shell 10, thereby improving the welding strength.

[0075] In another feasible embodiment, referring to Figure 7As shown, a step structure is formed at the connecting portion 13 of the housing 10 and the connecting mating portion 21 of the cover 20, the step structure includes a first step and a second step, the cover 20 includes a cover body portion 201 and a cover extension portion 202 protruding at the center of the cover body portion 201, the first step includes a first step surface 211 and a second step surface 212, the first step surface 211 is formed on the bottom surface of the cover body portion 201, and the second step surface 212 is formed on the side of the cover extension portion 202, the housing 10 includes a housing body portion 10 1 and the housing extension portion 102 protruding from the edge of the housing body portion 101, the second step includes a third step surface 131 and a fourth step surface 132, the third step surface 131 is formed on the top surface of the housing body portion 101, and the fourth step surface 132 is formed on the side of the housing extension portion 102. When the cover body 20 is connected and assembled with the housing 10, the first step surface 211 is pressed against the third step surface 131, the second step surface 212 is in contact with the side of the accommodating cavity 11, and the fourth step surface 132 is in contact with the side of the housing extension portion 102.

[0076] Reference Figures 5 to 7 As shown, at least a portion of the cover 20 extends into the housing 10, and the thickness of the cover 20 extending into the housing 10 is h1, satisfying the following relationship: 0.2mm≤h1≤2mm. Extending the cover 20 a certain distance into the housing 10 can increase the contact area between the cover 20 and the housing 10, thereby increasing the burst pressure N of the weld wire portion 12 and preventing bursting from the weld wire portion 12. When the step structure is formed on the connection and mating portion 21 of the cover 20, the cover extension portion 202 extends into the housing 10, and the thickness of the cover extension portion 202 is the distance h1 that the cover 20 extends into the housing 10. When the step structure is formed on the connection portion 13 of the housing 10, the cover 20 at least partially extends into the housing 10. When the step structure is formed on both the connection portion 13 of the housing 10 and the connection and mating portion 21 of the cover 20, the entire cover extension portion 202 and at least a portion of the cover body portion 201 extend into the opening.

[0077] The distance h1 that the cover body 20 extends into the shell 10 needs to be adjusted within a reasonable range to avoid being too large or too small. When the distance h1 that the cover body 20 extends into the shell 10 is too small and does not reach the minimum preset range value, the bursting pressure N of the welding wire portion 12 does not increase significantly. When the distance h1 that the cover body 20 extends into the shell 10 is too large and exceeds the maximum preset range value, on the one hand, the manufacturing difficulty and cost are increased. On the other hand, the bursting pressure N of the welding wire portion 12 is too large. When a large amount of gas is generated inside the battery 100, the pressure rises rapidly. Although the weak portion 31 will rupture first, it may not be able to effectively release sufficient pressure. At this time, since the bursting pressure N of the welding wire portion 12 is too large, the welding wire portion 12 does not explode in time, and the gas explodes from a large area of ​​the shell 10. At this time, the intensity of the explosion is serious, causing thermal runaway of the battery 100.

[0078] In a feasible implementation, referring to Figure 5 As shown, the cover 20 is disposed on the first wall 15 of the housing. The housing has a second wall 16 adjacent to the first wall 15. In the embodiment provided by the present disclosure, the first wall 15 serves as the top wall of the housing, the second wall 16 serves as the side wall of the housing, and the weld line portion 12 is located on the second wall 16. The ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line portion 12 satisfies the following relationship: 0.5 ≤ M / N ≤ 0.95. By increasing the lower limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line portion 12, the difference in bursting pressure between the two is reduced.

[0079] When a large amount of gas is generated inside the battery 100, the pressure rises rapidly. After the weak portion 31 ruptures, the gas mainly impacts the pressure relief member 30. Since the welding wire portion 12 is located on the side of the shell 10, the impact force on the welding wire portion 12 is relatively small, that is, the deformation direction of the cover 20 is perpendicular to the penetration direction of the welding wire portion 12, while the impact force on the shell 10 is relatively large. When the gas production inside the battery 100 is too large and the pressure relief member 30 has no time to relieve the pressure, the welding wire portion 12 needs to rupture earlier than the shell 10. If the bursting pressure N of the welding wire portion 12 is very different from the bursting pressure M of the weak portion 31, then after the weak portion 31 ruptures, the welding wire portion 12 still has to withstand a large impact force before it ruptures. It is possible that before the welding wire portion 12 ruptures, the shell 10 has already suffered a greater impact force and exploded on a large scale. At this time, the intensity of the explosion is severe and will also cause thermal runaway of the battery 100.

[0080] In another feasible embodiment, referring to Figure 6 As shown, the cover 20 is disposed on the first wall 15 of the housing, and the weld line portion 12 is located on the first wall 15. The ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line portion 12 satisfies the following relationship: 0.08 ≤ M / N ≤ 0.7. By reducing the upper limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld line portion 12, the difference between the bursting pressures is increased.

[0081] When a large amount of gas is generated inside the battery 100, the pressure rises rapidly. After the weak portion 31 ruptures, the gas primarily impacts the pressure relief member 30. Since the weld portion 12 is located on the top surface of the housing 10, it is directly impacted. The bursting pressure N of the weld portion 12 is very close to the bursting pressure M of the weak portion 31. Therefore, when gas is generated inside the battery 100, the internal pressure of the battery 100 may rise rapidly. After exceeding the bursting pressure M of the weak portion 31, the internal pressure of the battery 100 quickly reaches the bursting pressure N of the weld portion 12. If the weak portion 31 fails to rupture in time, the battery 100 cannot release the pressure through the weak portion 31 in time when the internal pressure rises. The pressure may directly act on the weld portion 12, causing the weld portion 12 to rupture and the cover 20 to fly out. This may cause the gas, electrolyte, metal chips, etc. in the battery 100 to be sprayed onto adjacent batteries 100, triggering thermal runaway.

[0082] Furthermore, the weld line 12 has a penetration depth c and a weld width d that satisfy the following relationships: 0.1 mm ≤ c ≤ 1.8 mm, and 0.2 mm ≤ d ≤ 2 mm. Keeping the penetration depth c and weld width d within a predetermined range not only improves the connection strength and sealing of the battery 100 housing, but also ensures the stability of the weld line 12 under increased pressure.

[0083] If the penetration depth c and the weld width d do not reach the minimum preset range value, the welding may be insufficient, affecting the connection strength and sealing of the weld wire portion 12, and causing the weld wire portion 12 to rupture in an unexpected scenario. If the penetration depth c and the weld width d exceed the maximum preset range value, the bursting pressure N of the weld wire portion 12 will be too large, exceeding the bursting pressure of the shell 10. When the gas production inside the battery 100 is too large, it cannot explode before the shell 10.

[0084] Further, refer to Figures 5 to 7 As shown, the thickness of the housing 10 is e, which satisfies the following relationship: 0.3mm≤e≤0.8mm. Controlling the thickness e of the housing 10 within a predetermined range ensures that the battery 100 housing has sufficient strength to withstand internal pressure and prevent explosion under normal use conditions, while also achieving high space utilization.

[0085] If the thickness e of the casing 10 does not meet the minimum preset range, the casing 10 may be insufficiently strong and prone to explosion when pressure increases, affecting the safety of the battery 100. If the thickness e of the casing 10 exceeds the maximum preset range, it will occupy more space, reducing the overall energy density and space utilization of the battery 100.

[0086] In a feasible implementation, referring to Figure 1 and Figure 2As shown, the pressure relief member 30 is provided on the cover 20 , and the cover 20 is further provided with a pole assembly 60 . The ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the welding wire portion 12 satisfies the following relationship: 0.08≤M / N≤0.75.

[0087] One end of the terminal assembly 60 is electrically connected to the electrode assembly housed within the housing. The terminal assembly 60 is used to extract electrical energy from the battery 100. Two terminal assemblies 60 are typically provided, one for the positive electrode and one for the negative electrode. Because the terminal assembly 60 is installed by drilling holes in the cover 20, it reduces the strength of the cover 20, thereby affecting the connection strength between the cover 20 and the housing 10, resulting in a decrease in the burst pressure N of the weld wire portion 12.

[0088] By reducing the upper limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12, the difference in bursting pressure between the two is made greater. When a large amount of gas is generated inside the battery 100, the pressure rises rapidly, and the weak portion 31 will rupture earlier to release the pressure as soon as possible, preventing the pressure from continuing to rise to the bursting pressure N of the weld portion 12. Even if the internal pressure of the battery 100 suddenly increases, the weld portion 12 is not likely to rupture due to the large margin between the bursting pressure M of the weak portion 31 and the bursting pressure N of the weld portion 12, thereby preventing the cover 20 from flying out and causing thermal runaway of the battery 100.

[0089] In the embodiment provided herein, the volume of the housing's interior is v1, the volume of the unoccupied portion of the interior is v2, and v1 and v2 have the same unit. The burst pressure M of the weak portion 31 and the burst pressure N of the weld portion 12 satisfy the following relationship: 0.05 ≤ v2 / v1 ≤ 0.2. Keeping this ratio within a predetermined range ensures the safety of the battery 100 and its overall energy density.

[0090] If the ratio does not reach the minimum preset range, the volume v2 of the unoccupied portion of the internal space is too small, and the gas has a greater impact on the weak portion 31 and the weld portion 12. After the weak portion 31 bursts, the gas inside the accommodating cavity 11 is still not fully released, thus impacting the weld portion 12, making it more likely to burst and causing the cover 20 to fly out. If the ratio exceeds the maximum preset range, the volume v2 of the unoccupied portion of the internal space is too large, occupying more space and reducing the overall energy density and space utilization of the battery 100.

[0091] In a feasible embodiment, the shell 10 includes an opening portion for installing the cover body 20, and the cover body 20 is welded to the opening portion. A thickened area is provided in the shell, and the distance between the thickened area and the cover body 20 is ≤3-15mm, so as to enhance the strength and stability of the opening portion, improve the pressure resistance of the weld and the reliability of the overall structure. The ratio of the maximum thickness of the thickened area to the minimum thickness of the shell 10 is between 1.05 and 1.6. This can ensure that the thickness of the thickened area is slightly larger than the minimum thickness of the shell 10, thereby providing additional strength support, enhancing the pressure resistance of the opening portion, and preventing cracks or deformation due to stress concentration during welding or use. It can also avoid the structure being too bulky or increasing material costs due to the thickened area being too thick.

[0092] Those skilled in the art will appreciate that battery 100 can also be a sodium-ion battery. Sodium-ion batteries have higher internal resistance than lithium-ion batteries, resulting in less instantaneous heat generation and a lower temperature rise in the event of a short circuit. Their thermal runaway temperature is higher than that of lithium batteries, offering greater safety. Therefore, the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12 is limited to 0.08 ≤ M / N ≤ 0.65. By reducing the upper limit of the ratio of the bursting pressure M of the weak portion 31 to the bursting pressure N of the weld portion 12, the difference in bursting pressures is increased. When a large amount of gas is generated within battery 100, the weak portion 31 ruptures earlier to release the pressure as quickly as possible. Because sodium-ion batteries have higher internal resistance and higher thermal runaway temperatures, they generate relatively less heat during normal operation and abnormal conditions. Therefore, a larger margin can be created between the bursting pressure M of the weak portion 31 and the bursting pressure N of the weld portion 12, making the weld portion 12 less likely to rupture and preventing the cover 20 from flying off and causing thermal runaway of battery 100.

[0093] When the battery 100 has a relatively large capacity, for example, a capacity ≥ 200Ah, the heat generated during charging and discharging increases significantly. This high heat generation also increases the internal pressure of the battery 100. This can cause deformation of the housing and even make it difficult for the weld to withstand excessive pressure. Therefore, the ratio of the burst pressure M of the weak portion 31 to the burst pressure N of the weld 12 is limited to 0.4 ≤ M / N ≤ 0.75. This ensures that the battery will not easily rupture under normal operating pressure while allowing for timely pressure relief in abnormal situations.

[0094] Preferably, the burst pressure M of the weak portion 31 satisfies the following relationship: 0.3 MPa ≤ M ≤ 2.5 MPa. Controlling the burst pressure M of the weak portion 31 within a predetermined range ensures that, when the internal pressure of the battery 100 abnormally increases, the weak portion 31 will promptly rupture and release pressure, thereby preventing thermal runaway or explosion of the battery 100. Furthermore, under normal operating conditions, the pressure relief member 30 will not be triggered to release pressure, thereby improving the overall reliability of the battery 100.

[0095] If the bursting pressure M of the weak portion 31 does not reach the minimum preset range value, the weak portion 31 will rupture before the internal pressure of the battery 100 reaches a dangerous level, releasing internal gas or pressure, causing the battery 100 to frequently falsely trigger pressure relief under normal working conditions, and failing to effectively protect the battery 100 structure.

[0096] If the bursting pressure M of the weak portion 31 exceeds the maximum preset range value, and the bursting pressure M of the weak portion 31 is very close to the bursting pressure N of the weld wire portion 12, then when gas is generated inside the battery 100, the internal pressure of the battery 100 may rise rapidly. After exceeding the bursting pressure M of the weak portion 31, the internal pressure of the battery 100 quickly reaches the bursting pressure N of the weld wire portion 12. If the weak portion 31 cannot be ruptured in time, the battery 100 cannot release the pressure through the weak portion 31 in time when the internal pressure rises. The pressure may directly act on the weld wire portion 12, causing the weld wire portion 12 to rupture and the cover 20 to fly out, causing the gas, electrolyte, metal chips, etc. in the battery 100 to be sprayed onto adjacent batteries 100, triggering thermal runaway.

[0097] Preferably, the burst pressure N of the weld line portion 12 satisfies the following relationship: 1.5 MPa ≤ N ≤ 5 MPa. Controlling the burst pressure N of the weld line portion 12 within a preset range ensures that when the pressure rises abnormally, the weld line portion 12 can work in conjunction with the explosion-proof valve, optimizing the burst path and reducing safety risks.

[0098] If the burst pressure N of the welding wire portion 12 does not reach the minimum preset range value, and if the internal pressure of the battery 100 continues to rise after the weak portion 31 ruptures, the welding wire portion 12 is likely to rupture, causing the cover 20 to fly out, and the gas, electrolyte, metal chips, etc. in the battery 100 to be sprayed onto adjacent batteries 100, causing thermal runaway.

[0099] If the bursting pressure N of the welding wire portion 12 exceeds the maximum preset range value, when excessive gas is generated inside the battery 100, the weak portion 31 cannot meet the pressure relief requirements, and the battery 100 cannot burst from the welding wire portion 12. The internal pressure of the battery 100 may exceed the bearing capacity of the shell 10, resulting in a large-scale explosion from the shell 10. At this time, the explosion is severe and may also cause thermal runaway of the battery 100.

[0100] Preferably, the shortest distance L between the weak portion 31 and the welding line portion 12 satisfies the following relationship: 2mm≤L≤30mm. By controlling the shortest distance L between the weak portion 31 and the welding line portion 12 within a preset range, the overall reliability of the battery 100 can be improved, and failure or safety issues of the battery 100 caused by improper distance design can be reduced.

[0101] If the shortest distance L between the weak portion 31 and the welding line portion 12 does not reach the minimum preset range value, the distance between the weak portion 31 and the welding line portion 12 is too close. When the internal pressure of the battery 100 increases, the pressure may be quickly transmitted from the weak portion 31 to the welding line portion 12. Before the weak portion 31 ruptures, the welding line portion 12 may have already felt the excessive pressure. If the pressure cannot be effectively released after the weak portion 31 ruptures, it may cause the welding line portion 12 to rupture and the cover 20 to fly out, causing thermal runaway of the adjacent battery 100.

[0102] If the shortest distance L between the weak portion 31 and the welding line portion 12 exceeds the maximum preset range value, the distance between the weak portion 31 and the welding line portion 12 is too far. When a large amount of gas is generated inside the battery 100, the pressure rises rapidly. Although the weak portion 31 will rupture first, it may not be able to effectively release sufficient pressure. The pressure continues to rise, and the gas production inside the battery 100 is too large. The pressure released when the weak portion 31 ruptures cannot be transmitted to the welding line portion 12 in time, resulting in the cover 20 being unable to open in time for pressure relief. The internal pressure of the battery 100 may exceed the bearing capacity of the shell 10, resulting in a large-scale explosion from the shell 10. At this time, the intensity of the explosion is severe and may also cause thermal runaway of the battery 100.

[0103] In the embodiment provided herein, the pressure relief component 30 is an explosion-proof valve and undergoes annealing at a temperature of 370°C ≤ e ≤ 420°C and a duration of 50 min ≤ f ≤ 70 min. The annealing temperature is restricted to a suitable range to eliminate stress within the material, improve its toughness and plasticity, and thereby enhance the reliability and safety of the pressure relief component 30. The annealing duration is also restricted to a suitable range to ensure that the material is adequately heated and cooled during the annealing process to achieve the desired performance improvement.

[0104] The battery 100 provided in the present disclosure can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel metal hydride battery, a nickel cadmium battery, a lead storage battery, etc., without limitation.

[0105] A single battery cell may generally include a casing, a battery cell, an adapter, and an electrolyte. The casing is used to hold the battery cell and the electrolyte. The casing generally includes a shell 10 and a cover 20. At least one positive electrode post and at least one negative electrode post are provided on the shell 10 and / or the cover 20. The battery cell includes one or more electrode assemblies. The electrode assembly is formed by stacking or winding positive electrode sheets, negative electrode sheets, and a separator. The separator is located between adjacent positive and negative electrode sheets to insulate the positive and negative electrode sheets. At least one end of the electrode assembly has a tab. One end of the adapter is electrically connected to the tab, and the other end is electrically connected to the post.

[0106] The shell 10 has an opening on one side, and the cover 20 is fixed to the opening of the shell 10 by welding. The shell 10 and / or the cover 20 are provided with a pressure relief member 30 to explode when the internal pressure of the battery reaches a certain level.

[0107] Taking the wound battery cell as an example, the specific preparation process is as follows: the positive electrode sheet, the negative electrode sheet and the diaphragm are wound to form an electrode assembly, and the electrode ear is led out at one end of the electrode assembly. When the electrode ear is fixed to the adapter, the electrode assembly and the electrode ear are first placed along the direction of the electrode ear lead-out, and then the electrode ear of the electrode assembly is welded to the electrode ear welding area of ​​the adapter, and then the adapter and the pole on the cover plate are welded to the pole welding area of ​​the adapter. After welding is completed, the pole column and the electrode are located on the same side in the thickness direction of the adapter, and then the electrode assembly is folded along the connection position between the electrode ear and the electrode assembly so that the electrode assembly and the pole are located on both sides of the thickness direction of the adapter, the folded electrode assembly is put into the shell, and the cover body 20 and the shell body 10 are welded and sealed, liquid is injected, formed, and the liquid injection hole is sealed to obtain a single cell.

[0108] The present disclosure also provides a thermal runaway testing method, comprising the following steps:

[0109] 1. Charge the battery. Specific charging strategies for nickel-cobalt-manganese ternary materials, lithium iron phosphate cathode materials, lithium iron manganese phosphate cathode materials, lithium-rich manganese-based cathode materials, and lithium nickel manganese oxide cathode materials are as follows: nickel-cobalt-manganese ternary materials are charged at a current of 1C to 4.25V, and then charged at a constant voltage until the current drops to 0.05C; lithium iron phosphate is charged at a constant current of 0.5C to 3.65V, and then charged at a constant voltage until the current drops to 0.05C; lithium iron manganese phosphate is charged at 0.5C to 4.25V, and then charged at a constant voltage until the current drops to 0.05C; lithium iron manganese phosphate is charged at 0.5C to 4.25V, and then charged at a constant voltage until the current drops to 0.05C; lithium-rich manganese-based materials are charged at 0.5C to 4.25V, and then charged at a constant voltage until the current drops to 0.05C; and lithium nickel manganese oxide is charged at 1C to 4.85V, and then charged at a constant voltage until the current drops to 0.05C.

[0110] 2. Place a heating plate on the large surface of the battery and heat the trigger object with the maximum power of the heating device.

[0111] 3. When thermal runaway occurs or the temperature at the monitoring point reaches 300°C, stop triggering and turn off the heating device. Observe whether the cover flies off during thermal runaway and whether the housing 10 is deformed or cracked.

[0112] Furthermore, the thermal runaway determination conditions are as follows: the triggering object generates a voltage drop, and the drop value exceeds 25% of the initial voltage; the temperature rise rate dT / dt of the monitoring point is ≥ 1°C / s, and lasts for more than 3s, then thermal runaway is determined to have occurred.

[0113] Based on the thermal runaway test method provided above, a number of batteries were selected for each embodiment and comparative example. The bursting pressure N of the weld line 12 formed at the weld between the cover 20 and the shell 10 and the bursting pressure M of the weak portion 31 of the pressure relief member 30 were set according to the table below. Other than that, all other battery features were identical.

[0114]

[0115]

[0116] Analysis of the table above reveals that the batteries in Examples 1-14 maintained the ratio (M / N) of the burst pressure M of the weak portion 31 to the burst pressure N of the weld portion 12 within the range of 0.08-0.95. Consequently, both cover 20 flying out and housing 10 deformation performed well, meeting design requirements. However, the M / N ratios in Comparative Examples 1-7 exceeded or fell below the range, resulting in cover 20 flying out and housing 10 deformation.

[0117] In a second aspect, embodiments of the present disclosure further provide a battery pack comprising the aforementioned battery 100. The battery pack is a battery module or battery pack, comprising at least two batteries 100, with two adjacent batteries 100 being electrically connected via a conductive bus.

[0118] The battery module includes a mounting bracket and a plurality of batteries 100 , and the plurality of batteries 100 can be fixed on the mounting bracket.

[0119] The battery pack includes a battery case and multiple batteries. The multiple batteries 100 can be assembled into a battery module and then installed in the battery case. Alternatively, the multiple batteries 100 can be directly placed in the battery case, i.e., the multiple batteries 100 do not need to be grouped together, and the battery case can be used to secure the multiple batteries 100.

[0120] In a third aspect, an embodiment of the present disclosure further provides an electrical device, which may include the above-mentioned battery pack.

[0121] By way of example only, the electrical equipment may be, but is not limited to, a vehicle, a ship, an aircraft, a household appliance, an industrial equipment, etc. For example, the vehicle may be a car, a truck, an engineering vehicle, etc.

[0122] In addition, electrical equipment can also be used to store, convert and release recyclable electrical energy.

[0123] In one feasible embodiment, the electrical device is an electric vehicle. The electric vehicle includes a chassis and a battery box, which is fixedly connected to the chassis. The battery box includes a base plate and a frame. The base plate is the bottom planar portion of the battery box and serves to support and protect the battery pack. The frame is a framework structure surrounding the base plate. The base plate and frame define a storage space. The battery pack is positioned within the storage space and fixedly connected to the base plate. The specific method of fixing can be bolts, clips, welding, etc., depending on the design requirements of the battery pack and battery box. This effectively prevents the battery pack from shaking or shifting during vehicle driving, bumps, or collisions, reducing the risk of battery damage.

[0124] Furthermore, the pressure relief member 30 is arranged toward the bottom plate. When the internal pressure of the battery is too high and needs to be relieved, the gas or liquid generated by the pressure relief is directed to the bottom instead of being sprayed upward or to the side, thereby ensuring the safe pressure relief of the pressure relief member and avoiding safety risks such as fire in the passenger compartment. The battery 100 also includes a pole assembly, and the pole assembly and the pressure relief member 30 are arranged on different surfaces of the battery. The pole assembly and the pressure relief member 30 can be arranged on two opposite surfaces or on other surfaces, which are not limited here. In this way, the pressure relief member 30 can be prevented from causing damage to the pole assembly during pressure relief, achieving thermal and electrical separation, and improving the overall safety of the battery pack.

[0125] Preferably, the battery box has an opening formed at its top, and the chassis covers the opening and is fixedly connected to the frame. The chassis not only supports and protects the battery box but also serves as a cover for the battery box, sealing the opening. This allows the battery box and chassis to form a single, integrated structure, enhancing the overall rigidity and stability of the vehicle and protecting the battery pack from environmental influences.

[0126] Because the battery compartment's opening faces the electric vehicle's chassis, the passenger compartment presents a significant safety risk. Therefore, the fire risk is mitigated by selecting the safer lithium iron phosphate battery. Specifically, the battery comprises a cell, which includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. The positive electrode sheet is made of lithium iron phosphate. Lithium iron phosphate has excellent thermal and chemical stability, making it less susceptible to thermal runaway or combustion even at high temperatures or under overcharge conditions.

[0127] Furthermore, because the battery 100 is relatively close to the electric vehicle chassis, the passenger compartment safety risk is increased. Therefore, the burst pressure M of the weak portion 31 is limited to satisfy the following relationship: 0.5 MPa ≤ M ≤ 2 MPa. This ensures that the weak portion 31 does not rupture prematurely due to excessively low pressure, avoiding unnecessary pressure release under normal operating conditions and thus ensuring the normal operation of the battery 100. Furthermore, it ensures that the pressure generated during pressure release is not excessive, thereby preventing the electric vehicle chassis from breaking through and preventing the released pressure material from entering the passenger compartment, thus reducing safety risks.

[0128] The above describes in detail the structure, features and effects of the present disclosure based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present disclosure, but the present disclosure is not limited to the scope of implementation shown in the drawings. Any changes made in accordance with the concept of the present disclosure, or modifications to equivalent embodiments with equivalent changes, which do not exceed the spirit covered by the description and drawings, should be within the scope of protection of the present disclosure.

Claims

1. A battery, characterized in that: The invention comprises an outer shell, wherein the outer shell comprises a shell and a cover, wherein the shell and the cover are welded to form an accommodating cavity, a welding line portion is formed at the welding point between the cover and the shell, and a pressure relief component is provided on the outer shell, wherein the pressure relief component has a weak portion, the bursting pressure of the weak portion is M, and the bursting pressure of the welding line portion is N, wherein 0.08≤M / N≤0.

95.

2. The battery according to claim 1, characterized in that The shortest distance between the weak portion and the welding line portion is L, wherein 0.01≤M / (N×L)≤0.

4.

3. The battery according to claim 1, characterized in that The pressure relief member is provided on the cover body, wherein 0.08≤M / N≤0.

8.

4. The battery according to claim 3, characterized in that The cover body is provided with a pressure relief through hole, and the pressure relief member is provided to cover the pressure relief through hole and is welded to the cover body.

5. The battery according to claim 1, characterized in that The pressure relief member is provided on a surface of the shell body opposite to the cover body, wherein 0.3≤M / N≤0.

95.

6. The battery according to claim 1, characterized in that The surface of the housing on which the weak portion is arranged is the first surface, and a dimension of the weak portion along the length direction of the first surface is greater than a dimension of the weak portion along the width direction of the first surface.

7. The battery according to claim 1, characterized in that The weak portion is a first groove formed on the pressure relief member.

8. The battery according to claim 7, characterized in that The groove depth of the first groove is t, and the thickness of the pressure relief member is T, wherein 0.05≤t / T≤0.

6.

9. The battery according to claim 7, characterized in that The first groove is provided on a surface of the pressure relief member facing away from the accommodating cavity or a surface facing the accommodating cavity.

10. The battery according to claim 7, characterized in that It also includes a second groove, and the first groove and the second groove are respectively arranged on two opposite surfaces of the pressure relief member.

11. The battery according to claim 1, characterized in that The weak portion is a first groove formed on the pressure relief member, and the first groove is surrounded by an opening area. The area of ​​the opening area is s, wherein 80mm 2 ≤s≤1200mm 2 .

12. The battery according to claim 11, characterized in that A reinforcement portion is formed in the opening area, wherein 0.08≤M / N≤0.

65.

13. The battery according to claim 11, characterized in that The reinforcement portion and the weak portion are spaced apart at a distance of 0.3 mm to 4 mm.

14. The battery according to claim 11, characterized in that Also included is a protection piece, which covers the opening area.

15. The battery according to claim 1, characterized in that A boss is provided on the surface of the shell, and an air storage cavity is formed in the boss. The air storage cavity has a first end and a second end. The first end of the air storage cavity is communicated with the accommodating cavity, and the second end of the air storage cavity forms an opening on the boss. The pressure relief member covers the opening. The weak portion is a first groove formed in the pressure relief member. The distance between the surface of the boss and the bottom surface of the first groove is b, wherein 0.1mm≤b≤0.6mm.

16. The battery according to claim 15, characterized in that The ratio of the bursting pressure M of the weak portion to the bursting pressure N of the weld line portion satisfies the following relationship: 0.4≤M / N≤0.

95.

17. The battery according to claim 1, characterized in that The shell has a connecting portion at the opening, and the cover body has a connecting fitting portion. The connecting portion and the connecting fitting portion are connected by welding, and the welding wire portion is formed between the connecting portion and the connecting fitting portion. The connecting portion and / or the connecting fitting portion are provided with a step structure.

18. The battery according to claim 17, characterized in that At least a portion of the cover extends into the shell, and a thickness of the at least portion is h1, wherein 0.2 mm ≤ h1 ≤ 2 mm.

19. The battery according to claim 17, characterized in that The step structure includes a first step formed at the connecting portion.

20. The battery according to claim 17, wherein The step structure includes a second step formed at the connecting portion.

21. The battery according to claim 1, characterized in that The material of the shell is steel, wherein 0.15≤M / N≤0.

95.

22. The battery according to claim 1, characterized in that The material of the housing is aluminum, wherein 0.4≤M / N≤0.

95.

23. The battery according to claim 1, characterized in that The shell is a cylindrical structure, wherein 0.08≤M / N≤0.

5.

24. The battery according to claim 1, characterized in that The shell is a quadrangular prism structure, wherein 0.08≤M / N≤0.

75.

25. The battery according to claim 1, characterized in that The cover is disposed on a first wall of the housing, the housing has a second wall adjacent to the first wall, the welding line portion is located on the second wall, and 0.5≤M / N≤0.

95.

26. The battery according to claim 1, characterized in that The cover is disposed on the first wall of the housing, and the welding line portion is located on the first wall, wherein 0.08≤M / N≤0.

7.

27. The battery according to claim 1, characterized in that The penetration depth of the welding line portion is c, and the penetration width is d, wherein 0.1 mm ≤ c ≤ 1.8 mm, and 0.2 mm ≤ d ≤ 2 mm.

28. The battery according to claim 1, characterized in that The thickness of the shell is e, wherein 0.3 mm ≤ e ≤ 0.8 mm.

29. The battery according to claim 1, characterized in that The pressure relief member is provided on the cover body, and a pole assembly is further provided on the cover body, wherein 0.08≤M / N≤0.

75.

30. The battery according to claim 1, wherein The volume of the interior space of the housing is v1, and the volume of the unoccupied portion of the interior space is v2, wherein 0.05≤v2 / v1≤0.

2.

31. The battery according to any one of claims 1 to 24, characterized in that The shell includes an opening portion, the cover body is welded to the opening portion, a thickened area is provided in the shell, the distance between the thickened area and the cover body is 3-15 mm, and the ratio of the maximum thickness of the thickened area to the minimum thickness of the shell is between 1.05-1.

6.

32. The battery according to any one of claims 1 to 24, characterized in that The battery comprises a sodium ion battery, wherein 0.08≤M / N≤0.

65.

33. The battery according to claim 1, characterized in that The capacity of the battery is ≥200 Ah, wherein 0.4≤M / N≤0.

75.

34. The battery according to claim 1, characterized in that The bursting pressure M of the weak portion satisfies the following relationship: 0.3 MPa≤M≤2.5 MPa.

35. The battery according to claim 1, characterized in that The bursting pressure N of the welding line portion satisfies the following relationship: 1.5 MPa≤N≤5 MPa.

36. The battery according to claim 1, characterized in that The shortest distance between the weak portion and the welding line portion is L, wherein 2 mm ≤ L ≤ 30 mm.

37. A battery pack, characterized in that: The battery according to any one of claims 1 to 36, wherein the battery pack comprises at least two of the batteries, and two adjacent batteries are electrically connected via a conductive bus.

38. An electrical device, characterized in that: A battery pack comprising the battery pack of claim 37.

39. The electrical equipment according to claim 38, characterized in that: The electrical equipment is an electric vehicle, which includes a chassis and a battery box. The battery box is fixedly connected to the chassis. The battery box includes a bottom plate and a frame. The bottom plate and the frame form a storage space. The battery pack is arranged in the storage space and fixedly connected to the bottom plate.

40. The electrical equipment according to claim 39, characterized in that: The pressure relief member is arranged toward the bottom plate. The battery further comprises a pole assembly. The pole assembly and the pressure relief member are arranged on different surfaces of the battery.

41. The electrical equipment according to claim 39, characterized in that: An opening surface is formed on the upper portion of the battery box, and the chassis covers the opening surface and is fixedly connected to the surrounding frame.

42. The electrical equipment according to claim 41, characterized in that: The battery includes a battery cell, the battery cell includes a positive electrode plate, and the positive electrode plate includes lithium iron phosphate.

43. The electrical equipment according to claim 41, characterized in that: The bursting pressure M of the weak portion satisfies the following relationship: 0.5 MPa≤M≤2 MPa.

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