Battery and battery pack

Abstract

A battery (100) and a battery pack. The battery (100) comprises a casing (1) and an explosion-proof valve (2), wherein the explosion-proof valve (2) comprises welding portions (21), and the welding portions (21) are welded onto the casing (1); the explosion-proof valve (2) further comprises a weak portion (22), wherein the explosion-proof valve (2) or the casing (1) is provided with buffer structures (3), each buffer structure (3) is arranged close to the corresponding welding portion (21), and the buffer structures (3) are used for releasing the stress generated by welding of the welding portions (21).

Description

Batteries and battery packs

[0001] This application claims priority to Chinese Patent Application No. 202421851665.9, filed with the Chinese Patent Office on July 31, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, specifically to a battery and a battery pack. Background Technology

[0003] Explosion-proof valves are installed in the individual cells of power battery packs or energy storage battery packs, and these valves are crucial to the safety performance of the individual cells. In related technologies, the explosion-proof valves are usually welded to the housing, and the weld seam between the explosion-proof valve and the housing is close to the groove on the explosion-proof valve. Welding is usually performed using high-temperature laser welding. Invention Overview

[0004] The internal stress generated during the cooling process after welding exerts tensile force on the scoring of the explosion-proof valve, thus affecting the consistency of the scoring thickness and consequently the stability of the explosion-proof valve's burst value.

[0005] In a first aspect, embodiments of this application provide a battery, comprising:

[0006] case;

[0007] An explosion-proof valve includes a welded portion welded to the housing, and the explosion-proof valve also includes a weak point.

[0008] The explosion-proof valve or housing is provided with a buffer structure, which is located near the welded part and is used to release the stress generated during welding.

[0009] Secondly, embodiments of this application provide a battery pack, the battery pack including a housing and a plurality of batteries disposed inside the housing, the batteries being configured as described above. Beneficial effects

[0010] The battery provided in this application has a buffer structure on the casing or explosion-proof valve. The buffer structure is located close to the welded part. The buffer structure is used to release the stress generated during the welding of the welded part, thereby improving the stress transmission of the welded part to the weak part during the welding cooling process and affecting the thickness of the weak part.

[0011] The battery pack provided in this application includes multiple batteries. The battery pack is designed based on the aforementioned batteries, and its beneficial effects are the same as those of the aforementioned batteries, which will not be repeated here. Attached Figure Description

[0012] Figure 1 is a three-dimensional structural diagram of the battery provided in an embodiment of this application;

[0013] Figure 2 is a schematic cross-sectional view of the explosion-proof valve and the shell after welding according to Embodiment 1 of this application;

[0014] Figure 3 is a magnified view of a portion of Figure 2;

[0015] Figure 4 is a partial cross-sectional structural diagram of the explosion-proof valve provided in Embodiment 1 of this application;

[0016] Figure 5 is a perspective view of the explosion-proof valve provided in Embodiment 1 of this application;

[0017] Figure 6 is a perspective view of the explosion-proof valve provided in Embodiment 1 of this application from another angle;

[0018] Figure 7 is a schematic cross-sectional view of the explosion-proof valve and the shell after welding according to Embodiment 2 of this application;

[0019] Figure 8a is a magnified view of a portion of Figure 7;

[0020] Figure 8b is a magnified view of a portion of Figure 8a;

[0021] Figure 9 is a partial cross-sectional structural schematic diagram of the explosion-proof valve provided in Embodiment 2 of this application;

[0022] Figure 10 is a perspective view of the explosion-proof valve provided in Embodiment 2 of this application;

[0023] Figure 11 is another perspective view of the explosion-proof valve provided in Embodiment 2 of this application;

[0024] Figure 12 is a schematic cross-sectional view of the explosion-proof valve and the shell after welding according to Embodiment 3 of this application;

[0025] Figure 13 is a partial enlarged view of Figure 12;

[0026] Figure 14 is a partial cross-sectional structural schematic diagram of the explosion-proof valve provided in Embodiment 3 of this application;

[0027] Figure 15 is a schematic diagram of the battery pack structure provided in an embodiment of this application;

[0028] Icon labels:

[0029] 100. Battery; 1. Housing; 11. Second buffer groove; 2. Explosion-proof valve; 21. Welded part; 211. Outer surface of welded part; 22. Weak part; 221. First notch; 222. Second notch; 223. Outer surface of weak part; 224. Inner surface of second notch; 23. Base part; 231. First base part; 2311. Outer surface of first base part; 2312. Inner surface of first base part; 232. Second base part; 2321. Outer surface of second base part; 2322. Inner surface of second base part; 24. First buffer groove; 25. Reinforcing part; 26. Buffer cavity; 27. Arched part; 3. Buffer structure; 4. Box body Embodiments of the present invention

[0030] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the orientation shown in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0031] Embodiments of this application provide a battery pack, which can be a power battery pack used to store electrical energy and serve as a power source for electric vehicles and hybrid vehicles. The battery pack can also be an energy storage battery pack, comprising an energy storage container for storing electrical energy to provide various functions for the power system, such as a smart mobile grid. As shown in Figure 15, the battery pack includes a housing, multiple individual batteries, and a BMS (Battery Management System).

[0032] The enclosure is used to fix and protect multiple individual batteries and other components. The enclosure can be assembled from several sub-enclosures. Suitable materials for manufacturing the enclosure have good shock resistance, waterproofing, and insulation properties; suitable materials include metals or plastics. The enclosure has a hollow inner cavity, including a battery compartment for holding multiple batteries.

[0033] Multiple individual battery cells are arranged in a matrix within the battery compartment. These cells can be connected in series, in parallel, or a combination of both to give the battery pack the capacity and power suitable for the electrical equipment. Individual battery cells include lithium-ion batteries, nickel-metal hydride batteries, lead-acid batteries, lithium iron phosphate batteries, or multi-component composite material batteries.

[0034] The Battery Management System (BMS) is used to monitor, protect, and manage the operating status of the battery pack. The BMS can monitor and balance the voltage and temperature of each individual cell, and can also control the power and protection functions during the charging and discharging process of the battery pack.

[0035] The embodiments of this application provide a battery 100, which can be a cylindrical battery or a square battery. The single battery 100 includes a casing 1, an electrode assembly, and an electrolyte.

[0036] The housing 1 is configured to be made of a metal material with certain mechanical strength and corrosion resistance. Suitable metal materials include nickel or steel. The housing 1 has a hollow inner cavity, and the electrode assembly is housed in the inner cavity of the housing 1. The housing 1 is used to fix and protect the electrode assembly.

[0037] The electrode assembly includes a positive electrode, a separator, and a negative electrode. The separator is disposed between the positive electrode and the negative electrode and is used to separate the positive electrode and the negative electrode. The electrode assembly can be formed by winding the positive electrode, the separator, and the negative electrode to form a core assembly, or by stacking the positive electrode, the separator, and the negative electrode to form a stacked assembly.

[0038] The electrolyte fills the inside of the casing 1, so that the internal structure of the battery, such as the positive electrode and the negative electrode, is fully immersed in the electrolyte. The electrolyte acts as an ion transport carrier between the positive electrode and the negative electrode, maintaining the continuity of electron transport inside the battery, so that the battery can be charged and discharged normally.

[0039] In related technologies, explosion-proof valves are installed in the individual cells of power battery packs or energy storage battery packs. These explosion-proof valves are crucial to the safety performance of the individual cells. The explosion-proof valves are typically welded to the housing. The weld seam between the explosion-proof valve and the housing is close to the scoring on the explosion-proof valve. Welding is usually performed using high-temperature laser welding. Therefore, the internal stress generated during the cooling process after welding exerts tensile force on the scoring on the explosion-proof valve, thus affecting the consistency of the scoring thickness and the stability of the explosion-proof valve's burst value.

[0040] In the battery provided in the embodiments of this application, a buffer structure is added near the weld between the explosion-proof valve and the housing. This buffer structure is configured to buffer the effect of the stress generated by the cooling of the welded part of the explosion-proof valve on the weak part of the explosion-proof valve.

[0041] In some embodiments, as shown in Figures 1 to 3 and Figure 5, the battery 100 includes a housing 1, an explosion-proof valve 2, and a buffer structure 3.

[0042] When the battery 100 is a cylindrical battery, the housing 1 includes opposing top and bottom walls, and side walls connecting the top and bottom walls, with an explosion-proof valve disposed on the top wall. When the battery is a prismatic battery, the housing includes opposing top and bottom walls, and multiple side walls connecting the top and bottom walls, with an explosion-proof valve 2 disposed on the top wall, or the explosion-proof valve 2 disposed on at least one side wall.

[0043] The explosion-proof valve 2 is welded to the housing 1. The explosion-proof valve 2 includes a welded portion 21 and a weak portion 22. The welded portion 21 is located at the edge of the explosion-proof valve 2, and the weak portion 22 is located inside the explosion-proof valve. When the explosion-proof valve 2 is welded to the housing 1, the surface of the explosion-proof valve 2 or the surface of the housing 1 receives a large amount of laser energy, resulting in a large melting area. The interior of the explosion-proof valve 2 or the interior of the housing 1 receives a small amount of laser energy, resulting in a small melting area. Therefore, extending from the surface of the explosion-proof valve 2 or the housing 1 inwards, the cross-sectional area of ​​the welded portion 21 gradually decreases, and the cross-section of the welded portion 21 is triangular. The larger the melting area of ​​the explosion-proof valve's substrate, the greater the tensile stress generated by shrinkage during cooling. Therefore, the tensile stress on the outer surface of the explosion-proof portion is greater than the tensile stress inside the explosion-proof valve. In other alternative examples, the cross-section of the welded portion is rectangular, trapezoidal, or parallelogram-shaped.

[0044] The buffer structure 3 is located close to the welded part 21 of the explosion-proof valve 2. The buffer structure 3 can be located on the housing 1 or on the explosion-proof valve 2. By setting the buffer structure 3, the welded part 21 can release the tensile stress generated during the shrinkage process, thus effectively reducing the impact of the welded part 21 on the thickness of the weak part 22 during the cooling and shrinkage process.

[0045] In the first embodiment provided in this application, as shown in Figures 2 to 6, the buffer structure 3 includes a first buffer groove 24 disposed on the explosion-proof valve 2, and the first buffer groove 24 is disposed between the welded part 21 and the weak part 22.

[0046] By adding a first buffer groove 24 to the explosion-proof valve 2, the welded part 21 is disconnected from the weak part 22. The base material of the welded part 21 melts during the welding process and moves towards one side of the shell 1. As a result, during the cooling process after welding, the internal stress generated by the cooling contraction of the welded part 21 is disconnected by the first buffer groove 24 and will not be transmitted to the weak part 22. Therefore, the influence of the stress generated by the cooling contraction of the welded part 21 after welding on the thickness of the weak part 22 can be effectively improved.

[0047] In some embodiments, referring further to Figures 3 to 6, the explosion-proof valve 2 includes a first base portion 231 and a second base portion 232 connected together. The outer surface 2311 of the first base portion 231 is flush with the outer surface 2321 of the second base portion 232. The inner surface 2312 of the first base portion 231 protrudes inward relative to the inner surface 2322 of the second base portion 232, such that the thickness of the first base portion 231 is greater than the thickness of the second base portion 232.

[0048] Both the welding part 21 and the first buffer groove 24 are provided on the first base part 231, wherein the first buffer groove 24 extends from the outer surface 2311 of the first base part 231 to the interior of the first base part 231, and the welding part 21 is located on the side of the first base part 231 away from the second base part 232.

[0049] A weak portion 22 is disposed on the second base portion 232. The weak portion 22 includes a groove that extends from the inner surface 2322 of the second base portion 232 to the interior of the second base portion 232.

[0050] By placing both the welding part 21 and the first buffer groove 24 on the thicker first base part 231, it is beneficial to maintain the overall structural strength of the explosion-proof valve 2. By placing the weak part 22 on the thinner second base part 232, it is beneficial to ensure that the weak part 22 is disconnected first when the pressure inside the battery 100 exceeds the preset high pressure threshold.

[0051] Furthermore, the weak portion 22 extends from the inner surface 2322 of the second base portion 232 to the outer surface, and the first buffer groove 24 extends from the outer surface 2311 of the first base portion 231 to the interior, forming a disconnect between the first buffer groove 24 and the weak portion 22. This also prevents the formation of a new weak portion at the location of the first buffer groove 24, thereby affecting the stability of the opening pressure of the explosion-proof valve 2. Moreover, the heat of the weld portion 21 is concentrated on the outer surface 2311 of the first base portion 231. Therefore, the first buffer groove 24 is designed to extend from the outer surface 2311 of the first base portion 231 to its interior, causing the weld portion 21 to move closer to the housing 1 during the welding melting process, which is beneficial for the stable welding between the explosion-proof valve 2 and the housing 1.

[0052] In some embodiments, as shown in FIG4, the width d1 of the first buffer groove 24 is set to 0.1mm~3.0mm. In specific implementations, the width d1 of the first buffer groove 24 can be 0.1mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 1.9mm, 2.0mm, 2.3mm, 2.5mm, 2.6mm, 2.8mm, 3.0mm, or any value between any two of the above values, or a range between any two of the above values.

[0053] The inventors discovered through research that when the width d1 of the first buffer groove 24 is less than 0.1 mm, the first buffer groove 24 is too narrow, preventing the formation of a disconnect between it and the weak part 22. The stress generated during the cooling and shrinkage process of the welded part 21 may still be transmitted to the weak part 22 after passing through the first buffer groove 24. When the width d1 of the first buffer groove 24 is greater than 3.0 mm, the overall size of the first base part 231 increases, leading to an increase in the overall size of the explosion-proof valve 2, resulting in material waste and increased cost. Furthermore, it is not conducive to designing the aforementioned explosion-proof valve structure on the narrower sidewalls or top walls of the housing.

[0054] In some embodiments, referring to FIG4, the depth h1 of the first buffer groove 24 is set to be greater than 0.1 mm, and the ratio of the depth h1 of the first buffer groove 24 to the height of the first base portion 231 is not greater than 2 / 3.

[0055] The inventors discovered through research that when the depth h1 of the first buffer groove 24 is less than 0.1 mm, the first buffer groove 24 is not deep enough, thus preventing the formation of a disconnect structure between the first buffer groove 24 and the weak part 22. The stress generated during the cooling and shrinkage process of the welded part 21 may still be transmitted to the weak part 22 after passing through the first buffer groove 24. When the ratio of the depth h1 of the first buffer groove 24 to the height of the first base part 231 is greater than 2 / 3, the thickness of the first base part 231 where the first buffer groove 24 is located will be too thin, resulting in insufficient strength of the first base part 231, and even affecting the opening pressure of the explosion-proof valve 2.

[0056] In some embodiments, referring to FIG3, the width d2 of the welded portion 21 is set to 0.2mm to 2mm. In specific implementations, the width d2 of the welded portion 21 can be 0.2mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 1.9mm, 2.0mm, or any value between any two of the above values, or a range between any two of the above values.

[0057] The inventors discovered through research that when the width d2 of the welded part 21 is less than 0.2 mm, it leads to processing difficulties and prevents the explosion-proof valve 2 from forming a stable weld with the housing 1. When the width d2 of the welded part 21 is greater than 2.0 mm, the welded part 21 cannot be completely melted, affecting the weld quality between the explosion-proof valve 2 and the housing 1. Furthermore, the width d2 of the welded part 21 is too close to the width d1 of the first buffer groove 24, preventing the first buffer groove 24 from fully buffering the stress generated during the cooling process of the welded part 21, thus affecting the weak part 22.

[0058] In the second embodiment provided in this application, as shown in Figures 7 to 11, the buffer structure 3 includes a second buffer groove 11 disposed on the housing 1, and the second buffer groove 11 is located on the side of the welded part 21 away from the weak part 22.

[0059] By adding a second buffer groove 11 to the housing 1, which is located close to the welding part 21, the second buffer groove 11 can provide space for the deformation of the substrate of the welding part 21 during the welding and cooling process, so as to release the stress generated by welding, without transmitting it to the weak part 22 near the welding part 21. Therefore, it can effectively improve the influence of the stress generated by the cooling and shrinkage of the welding part 21 after welding on the thickness of the weak part 22.

[0060] In some embodiments, continuing to refer to Figures 7 to 11, the explosion-proof valve 2 includes a first base portion 231 and a second base portion 232 connected together. The outer surface 2311 of the first base portion 231 is flush with the outer surface 2321 of the second base portion 232. The inner surface 2312 of the first base portion 231 protrudes inward relative to the inner surface 2322 of the second base portion 232, such that the thickness of the first base portion 231 is greater than the thickness of the second base portion 232.

[0061] The welding part 21 is located on the first base part 231. The high temperature heat generated by the welding part 21 during the welding process gradually decreases along the outer surface 2311 of the first base part 231 towards its interior.

[0062] A weak portion 22 is provided on the second base portion 232. The weak portion 22 is configured as a groove structure and extends from the inner surface 2322 of the second base portion 232 to the interior of the second base portion 232.

[0063] The second buffer groove 11 of the housing 1 is located near the welding part 21 and is located on both sides of the welding part 21, respectively, along with the weak part 22. When the welding part 21 is being welded, the second buffer groove 11 allows the welding part 21 to deform, thereby releasing the stress generated by the welding part 21 during welding and cooling after welding. Therefore, it can effectively improve the transmission of stress generated by the welding part 21 during cooling after welding to the weak part 22.

[0064] In some embodiments, as shown in FIG8b, the width d3 of the second buffer groove 11 is set to 0.1mm~3.0mm. In specific implementations, the width d3 of the second buffer groove 11 can be 0.1mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 1.9mm, 2.0mm, 2.3mm, 2.5mm, 2.6mm, 2.8mm, 3.0mm, or any value between any two of the above values, or a range between any two of the above values.

[0065] The inventors discovered through research that when the width d3 of the second buffer groove 11 is less than 0.1 mm, the second buffer groove 11 is insufficient in width, thus failing to provide enough stress relief space, and the stress generated during the cooling and shrinkage process of the welded part 21 may still be transmitted to the weak part 22. When the width d3 of the second buffer groove 11 is greater than 3.0 mm, it will affect the overall structural strength of the shell 1.

[0066] In some embodiments, referring to FIG4, the depth h2 of the second buffer groove 11 is set to be greater than 0.1 mm, and the ratio of the depth h2 of the second buffer groove 11 to the thickness of the housing 1 is not greater than 2 / 3.

[0067] The inventors discovered through research that when the depth h2 of the second buffer groove 11 is less than 0.1 mm, the second buffer groove 11 is not deep enough, thus failing to provide sufficient stress relief space. The stress generated during the cooling and shrinkage process of the welded part 21 may still be transmitted to the weak part 22. When the ratio of the depth h2 of the second buffer groove 11 to the thickness of the shell 1 is greater than 2 / 3, it will result in a thinner shell 1 containing the second buffer groove 11, and will affect the structural strength of the shell 1.

[0068] In the third embodiment provided in this application, as shown in Figures 12 to 14, the buffer structure 3 includes a buffer cavity 26, such that a height difference H is formed between the outer surface 211 of the welded part 21 and the outer surface 223 of the weak part 22. The height difference H between the outer surface 211 of the welded part 21 and the outer surface 223 of the weak part 22 is set to be not less than 0.1 mm, and the height difference H between the outer surface 211 of the welded part 21 and the outer surface 223 of the weak part 22 is set to be not greater than 2 mm.

[0069] In some embodiments, the height H between the outer surface 211 of the welded portion 21 and the outer surface 223 of the weak portion 22 can be 0.1mm, 0.2mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 1.9mm, 2.0mm, or any two of the above values, or a range between any two of the above values.

[0070] Since the outer surface 223 of the weak part 22 is staggered from the outer surface 211 of the welded part 21, a buffer cavity 26 is formed between the outer surface 223 of the weak part 22 and the outer surface 211 of the welded part 21. The buffer cavity 26 provides stress release. The stress generated by the welded part 21 during welding and post-weld cooling is released in the buffer cavity 26 and will not be transmitted to the weak part 22.

[0071] Inventors typically find that when the height difference H between the outer surface 211 of the welded part 21 and the outer surface 223 of the weak part 22 is set to less than 0.1 mm, the height of the stress relief zone between the outer surface 223 of the weak part 22 and the outer surface 211 of the welded part 21 is insufficient, so that the stress generated by the welded part 21 during welding and post-weld cooling can still be transmitted to the weak part 22.

[0072] When the height difference H between the outer surface 211 of the welded part 21 and the outer surface 223 of the weak part 22 is set to be greater than 2mm, the stress relief zone will occupy more space in the thickness direction of the shell 1 and will reduce the structural strength of the shell 1.

[0073] In some embodiments, continuing to refer to FIG14, the explosion-proof valve 2 includes a first base portion 231 and a second base portion 232 connected together. The inner surface 2312 of the first base portion 231 is flush with the inner surface 2322 of the second base portion 232. The outer surface 2311 of the first base portion 231 protrudes relative to the outer surface 2321 of the second base portion 232. The weld portion 21 is located on the first base portion 231, and the weak portion 22 is located on the second base portion 232. The weak portion 22 is configured as a grooved structure and extends from the inner surface 2322 of the second base portion 232 to the interior of the second base portion 232.

[0074] By setting the outer surface 2311 of the first base portion 231 to protrude relative to the outer surface 2321 of the second base portion 232, it is beneficial to form a height difference structure between the weld portion 21 and the weak portion 22.

[0075] In the fourth embodiment provided in this application, the buffer structure 3 includes a second buffer groove 11 structure disposed on the housing 1 and a height difference structure disposed between the plane where the welded part 21 of the explosion-proof valve 2 is located and the plane where the weak part 22 is located, so that the second buffer groove 11 structure is formed on the left side of the welded part 21 and a stress buffer zone is formed on the right side of the welded part 21. The stress generated by the welded part 21 during welding and cooling after welding can be fully released into the second buffer groove 11 on its left side and the stress buffer zone on its right side, thus effectively preventing stress from being transmitted to the weak part 22.

[0076] In the above-described embodiments provided in this application, by offsetting the plane where the weak part 22 of the explosion-proof valve 2 is located from the outer surface 211 of the welded part 21, or by disconnecting the plane where the weak part 22 of the explosion-proof valve 2 is located from the outer surface of the welded part 21, the stress generated by the welded part 21 during welding and cooling cannot be transmitted to the weak part 22. Therefore, the overall thickness of the weak part 22 can be maintained, and the welding process can be avoided from affecting the thickness of the weak part 22.

[0077] The plane where the weak part is located is offset from the outer surface of the welded part, or the plane where the weak part is located is disconnected from the outer surface of the welded part.

[0078] In some embodiments, referring to Figures 5, 6, 9, and 10, the explosion-proof valve 2 includes a first base portion 231 and a second base portion 232 connected together, with a weak portion 22 located on the second base portion 232. The weak portion 22 includes a first notch 221 and a second notch 222, wherein the second notch 222 is configured to extend from the inner surface 2322 of the second base portion 232 toward its outer surface, and the first notch 221 is disposed on the inner surface 224 of the second notch 222 and extends from the inner surface 224 of the second notch 222 toward the outer surface 2321 of the second base portion 2322. The first notch 221 is configured as an unclosed annulus, and a gap is formed between the two ends of the first notch 221, which is configured as a part of the second notch 222, wherein the thickness of the first notch 221 is less than the thickness of the second notch 222.

[0079] When the internal pressure of the battery 100 exceeds a preset threshold, the first notch 221 disconnects first, while the second notch 222 keeps the first base portion 231 and the second base portion 232 connected, thereby preventing the explosion-proof valve 2 from forming a large pressure relief opening. The electrolyte inside the battery 100 would then spray out through the large pressure relief opening, affecting the safe use of the battery 100.

[0080] In some embodiments, as shown in Figures 5 and 10, a reinforcing portion 25 is provided on the second base portion 232. The thickness of the reinforcing portion 25 is greater than the thickness of the first notch 221. The reinforcing portion 25 includes three reinforcing segments. The beginning ends of the three reinforcing segments are all connected to the center of the second base portion 232, and the ends of the three reinforcing segments are connected to different positions of the first notch 221, thereby maintaining the overall structural strength of the explosion-proof valve 2.

[0081] In some embodiments, as shown in Figures 5 and 10, the second base portion 232 further includes an arched portion 27 disposed between the first notch 221 and the reinforcing portion 25. The arched portion 27 is configured to arch upwards along the outer surface 2321 of the second base portion 232 toward its inner surface. By configuring the area between the reinforcing portion 25 and the first notch 221 to arch upwards, the overall stability of the second base portion 232 of the explosion-proof valve 2 is enhanced, and it is beneficial for the explosion-proof valve 2 to open.

Claims

1. A battery (100), comprising: Shell (1); The explosion-proof valve (2) includes a welded part (21) which is welded to the housing (1). The explosion-proof valve (2) also includes a weak part (22). The explosion-proof valve (2) or the housing (1) is provided with a buffer structure (3), which is located near the welded part (21) and is configured to release the stress generated by the welding of the welded part (21).

2. The battery (100) according to claim 1, wherein, The buffer structure (3) includes a first buffer groove (24) disposed on the explosion-proof valve (2), the first buffer groove (24) being disposed between the welded part (21) and the weak part (22).

3. The battery (100) according to claim 2, wherein, The explosion-proof valve (2) includes a first base part (231) and a second base part (232) surrounded by the first base part (231). The outer surface (2311) of the first base part (231) is flush with the outer surface (2321) of the second base part (232). The inner surface (2312) of the first base part (231) protrudes inward relative to the inner surface (2322) of the second base part (232). The first buffer groove (24) is provided on the outer surface (2311) of the first base part (231). The weak part (22) includes a groove, which is provided on the inner surface (2322) of the second base part (232). The end of the first base part (231) away from the second base part (232) is the welded part (21).

4. The battery (100) according to claim 3, wherein, The width of the first buffer groove (24) is set to be not less than 0.1 mm and not more than 3 mm, and / or the depth of the first buffer groove (24) is set to be not less than 0.1 mm, and the ratio of the depth of the first buffer groove (24) to the height of the first base part (231) is not more than 2 / 3; and / or the width of the welded part (21) is set to be not less than 0.2 mm and not more than 2 mm.

5. The battery (100) according to claim 1, wherein, The buffer structure (3) includes a second buffer groove (11) disposed on the housing (1), the second buffer groove (11) being located on the side of the welded part (21) away from the weak part (22).

6. The battery (100) according to claim 5, wherein, The width of the second buffer groove (11) is set to be not less than 0.1 mm and not less than 3 mm, and / or the depth of the second buffer groove (11) is set to be greater than 0.1 mm, and the ratio between the depth of the second buffer groove (11) and the thickness of the shell (1) is not greater than 2 / 3; and / or the width of the welded part (21) is set to be 0.2 mm to 2 mm.

7. The battery (100) according to claim 1, wherein, The buffer structure (3) includes a buffer cavity (26) disposed in the explosion-proof valve (2), such that a height difference is formed between the outer surface where the welded part (21) is located and the outer surface where the weak part (22) is located, and the height difference is set to be not less than 0.1 mm and not more than 2 mm.

8. The battery (100) according to claim 7, wherein, The explosion-proof valve (2) includes a first base part (231) and a second base part (232) surrounded by the first base part (231). The inner surface (2312) of the first base part (231) is flush with the inner surface (2322) of the second base part (232). The outer surface (2311) of the first base part (231) protrudes outward relative to the outer surface (2321) of the second base part (232). The buffer cavity (26) is disposed on the outer surface (2321) of the second base part (232). The weak part (22) includes a groove, which is disposed on the inner surface (2322) of the second base part (232).

9. The battery (100) according to claim 5, wherein, The buffer structure (3) further includes a buffer cavity (26) disposed in the explosion-proof valve (2), so that a height difference is formed between the outer surface (211) where the welded part (21) is located and the outer surface (223) where the weak part (22) is located, and the height difference is set to be not less than 0.1 mm and not more than 2 mm.

10. The battery (100) according to claim 1, wherein, The explosion-proof valve (2) includes a first base part (231) and a second base part (232) connected together. The weak part (22) includes a first groove (221) and a second groove (222). The second groove (222) is disposed on the inner surface (2322) of the second base part (232), and the first groove (221) is disposed on the inner surface (224) of the second groove (222). The first groove (221) is configured as an unclosed annular shape.

11. The battery (100) according to claim 10, wherein, A reinforcing part (25) is provided on the second base part (232), and the thickness of the reinforcing part (25) is greater than the thickness of the second base part (232) where the first notch (221) is located.

12. The battery (100) according to claim 11, wherein, The explosion-proof valve (2) also includes an arched portion (27), which is located between the first notch (221) and the reinforcing portion (25). The arched portion (27) arches along the direction from the outer surface (2321) of the second base portion (232) to the inner surface (2322) of the second base portion (232).

13. A battery pack comprising a housing (4) and a plurality of batteries (100) disposed inside the housing (4), wherein the batteries are configured as the batteries according to any one of claims 1-12.

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