Battery and battery pack

Abstract

The utility model provides a battery and a battery pack. The battery comprises a shell and a battery pack, the explosion-proof valve comprises a welding part, the welding part is welded on the shell, and the explosion-proof valve further comprises a weak part; wherein the anti-explosion valve or the shell is provided with a buffer structure, the buffer structure is arranged close to the welding part, and the buffer structure is used for releasing stress generated by welding of the welding part.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a battery and a battery pack. Background Art

[0002] In related technologies, explosion-proof valves are installed in individual cells in power or energy storage battery packs. These valves are crucial to the safety of these cells. These valves are typically welded to the housing, with the weld between the valve and the housing being relatively close to the valve's notch. High-temperature laser welding is typically used, and the resulting internal stress during the cooling process after welding creates tension on the valve's notch, affecting the consistency of the notch's thickness and, in turn, the stability of the valve's burst value. Utility Model Content

[0003] The embodiments of the present utility model provide a battery and a battery pack, which can improve the technical problem of the instability of the explosion value of the welding explosion-proof valve.

[0004] In a first aspect, an embodiment of the present invention provides a battery, comprising:

[0005] case;

[0006] An explosion-proof valve, comprising a welding portion welded to the housing, and further comprising a weak portion;

[0007] The explosion-proof valve or the housing is provided with a buffer structure, and the buffer structure is provided close to the welding portion, and the buffer structure is used to release the stress generated by welding of the welding portion.

[0008] In one embodiment, the buffer structure includes a first buffer groove provided on the explosion-proof valve, and the first buffer groove is provided between the welding portion and the weak portion.

[0009] In one embodiment, the explosion-proof valve includes a first base portion and a second base portion surrounded by the first base portion, the outer surface of the first base portion is flush with the outer surface of the second base portion, and the inner surface of the first base portion is protruded inward relative to the inner surface of the second base portion; the first buffer groove is provided on the outer surface of the first base portion, the weak portion includes a notch, and the notch is provided on the inner surface of the second base portion, and the end of the first base portion away from the second base portion is the welding portion.

[0010] In one embodiment, the width of the first buffer groove is set to 0.1 mm to 3 mm, and / or the depth of the first buffer groove is set to be greater than 0.1 mm, and the ratio of the depth of the first buffer groove to the height of the first base portion is not greater than 2 / 3; and / or the width of the welding portion is set to 0.2 mm to 2 mm.

[0011] In one embodiment, the buffer structure includes a second buffer groove provided on the shell, and the second buffer groove is located on a side of the welding portion away from the weak portion.

[0012] In one embodiment, the width of the second buffer groove is set to 0.1 mm to 3 mm, and / or the depth of the second buffer groove is set to be greater than 0.1 mm, and the ratio of the depth of the second buffer groove to the thickness of the shell is not greater than 2 / 3; and / or the width of the welding portion is set to 0.2 mm to 2 mm.

[0013] In one embodiment, the buffer structure includes a buffer cavity arranged in the explosion-proof valve, so that a height difference is formed between the outer surface where the welding part is located and the outer surface where the weak part is located, and the height difference is set to be not less than 0.1 mm and not more than 2 mm.

[0014] In one embodiment, the explosion-proof valve includes a first base portion and a second base portion surrounded by the first base portion, the inner surface of the first base portion is flush with the inner surface of the second base portion, and the outer surface of the first base portion is protruded outward relative to the outer surface of the second base portion; the buffer cavity is arranged on the outer surface of the second base portion, and the weak portion includes a notch, which is arranged on the inner surface of the second base portion.

[0015] In one embodiment, the buffer structure further includes a buffer cavity arranged in the explosion-proof valve, so that a height difference is formed between the outer surface where the welding portion is located and the outer surface where the weak portion is located, and the height difference is set to be not less than 0.1 mm and not more than 2 mm.

[0016] In one embodiment, the explosion-proof valve includes a first base portion and a second base portion connected to each other, the weak portion includes a first notch and a second notch, the second notch is arranged on the inner surface of the second base portion, the first notch is arranged on the inner surface of the second notch, and the first notch is arranged in an unclosed ring shape.

[0017] In one embodiment, a reinforcement portion is provided on the second base portion, and a thickness of the reinforcement portion is greater than a thickness of the second base portion where the first notch is located.

[0018] In one embodiment, the explosion-proof valve further includes a raised portion, the raised portion is located between the first notch and the reinforcement portion, and the raised portion is raised along the outer surface of the second base portion in a direction pointing toward the inner surface of the second base portion.

[0019] In a second aspect, an embodiment of the present invention provides a battery pack, comprising a box and a plurality of batteries disposed inside the box, wherein the batteries include the above-mentioned battery.

[0020] Beneficial effects of the embodiments of the present utility model:

[0021] In an embodiment of the present utility model, a buffer structure is provided on the shell or the explosion-proof valve, and the buffer structure is provided close to the welding part. The buffer structure is used to release the stress generated by the welding of the welding part, thereby improving the technical problem that the stress generated by the welding part during the welding cooling process is transferred to the weak part and affects the thickness of the weak part. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a schematic diagram of the three-dimensional structure of a battery provided in an embodiment of the present utility model;

[0024] Figure 2 This is a schematic cross-sectional view of the explosion-proof valve and the housing after welding according to the first embodiment of the present invention;

[0025] Figure 3 yes Figure 2 A partial enlarged view of

[0026] Figure 4 This is a schematic diagram of a partial cross-sectional structure of an explosion-proof valve provided in Example 1 of the present utility model;

[0027] Figure 5 This is a three-dimensional diagram of the explosion-proof valve provided in the first embodiment of the present utility model from one perspective;

[0028] Figure 6 This is a three-dimensional diagram of the explosion-proof valve provided in the first embodiment of the present utility model from another perspective;

[0029] Figure 7 This is a schematic cross-sectional view of the explosion-proof valve and the housing after welding, provided in the second embodiment of the present utility model;

[0030] Figure 8a yes Figure 7 A partial enlarged view of

[0031] Figure 8b yes Figure 8a A partial enlarged view of

[0032] Figure 9 This is a schematic diagram of a partial cross-sectional structure of an explosion-proof valve provided in Example 2 of the present utility model;

[0033] Figure 10 This is a three-dimensional diagram of the explosion-proof valve provided in the second embodiment of the present utility model from one perspective;

[0034] Figure 11 This is a three-dimensional diagram of the explosion-proof valve provided in the second embodiment of the present utility model from another perspective;

[0035] Figure 12 This is a schematic cross-sectional view of the explosion-proof valve and the housing after welding provided by the third embodiment of the present invention;

[0036] Figure 13 yes Figure 12 A partial enlarged view of

[0037] Figure 14 This is a schematic diagram of a partial cross-sectional structure of an explosion-proof valve provided in Example 3 of the present utility model;

[0038] Figure Number:

[0039] 100. Battery; 1. Housing; 11. Second buffer tank; 2. Explosion-proof valve; 21. Welding portion; 22. Weak portion; 221. First notch; 222. Second notch; 23. Base portion; 231. First base portion; 232. Second base portion; 24. First buffer tank; 25. Reinforcement portion; 26. Buffer cavity; 27. Arched portion; 3. Buffer structure; DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0041] An embodiment of the present application provides 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, which includes an energy storage container and is used to store electrical energy to provide various functions for power systems, such as smart mobile grids. The battery pack includes a housing, multiple single cells, and a BMS (battery management system).

[0042] The case is used to secure and protect multiple battery cells and other components. It can be assembled from several sub-cases. Suitable materials for the case include metal or plastic, which have excellent shock resistance, waterproofing, and insulation properties. The case has a hollow interior, including a battery chamber, which houses the multiple batteries.

[0043] Multiple single cells are arranged in a matrix within the battery cavity. The cells can be connected in series, in parallel, or in a combination of these, ensuring the battery pack has a capacity and power suitable for use in electrical equipment. Cells include lithium-ion batteries, nickel-metal hydride batteries, lead-acid batteries, lithium iron phosphate batteries, or composite materials.

[0044] BMS (Battery Management System) is used to monitor, protect and manage the working status of the battery pack. BMS can monitor and balance the voltage and temperature of each single cell, and can also control the power and protection functions of the battery pack during the charging and discharging process.

[0045] An embodiment of the present application provides a single cell 100 . The cell 100 may be a cylindrical cell or a square cell. The single cell 100 includes a housing 1 , an electrode assembly, and an electrolyte.

[0046] The shell 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 shell 1 has a hollow inner cavity, and the electrode assembly is accommodated in the inner cavity of the shell 1. The shell 1 is used to fix and protect the electrode assembly.

[0047] The electrode assembly includes a positive electrode sheet, a separator and a negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet and is used to separate the positive electrode sheet and the negative electrode sheet. The electrode assembly can be wound to form a core assembly by winding the positive electrode sheet, the separator and the negative electrode sheet. The electrode assembly can also be stacked to form a laminated assembly by stacking the positive electrode sheet, the separator and the negative electrode sheet.

[0048] The electrolyte is filled inside the shell 1, so that the internal structure of the battery, such as the positive electrode sheet and the negative electrode sheet, is fully immersed in the electrolyte. The electrolyte serves as an ion transmission carrier between the positive electrode sheet and the negative electrode sheet, maintaining the continuity of electron transmission inside the battery, so that the battery can be charged and discharged normally.

[0049] In related technologies, explosion-proof valves are installed in individual cells in power or energy storage battery packs. These valves are crucial to the safety of these cells. These valves are typically welded to the housing, with the weld between the valve and the housing being relatively close to the valve's notch. High-temperature laser welding is typically used, and the resulting internal stress during the cooling process after welding creates tension on the valve's notch, affecting the consistency of the notch's thickness and, in turn, the stability of the valve's burst value.

[0050] In the battery provided in the embodiment of the present application, a buffer structure is added near the weld between the explosion-proof valve and the shell. The buffer structure is configured to buffer the effect of stress generated by cooling of the weld of the explosion-proof valve on the weak part of the explosion-proof valve.

[0051] In some embodiments, as Figures 1 to 3 as well as Figure 5 As shown, the battery 100 includes a housing 1 , an explosion-proof valve 2 and a buffer structure 3 .

[0052] When the battery 100 is configured as a cylindrical battery, the housing 1 includes opposing top and bottom walls, as well as side walls connected between the top and bottom walls, and the explosion-proof valve is disposed on the top wall. When the battery is configured as a prismatic battery, the housing includes opposing top and bottom walls, as well as multiple side walls connected between the top and bottom walls. The explosion-proof valve 2 can be disposed on the top wall, or on at least one side wall.

[0053] The explosion-proof valve 2 is welded to the housing 1. The explosion-proof valve 2 includes a weld portion 21 and a weakened portion 22. The weld portion 21 is located at the edge of the explosion-proof valve 2, and the weakened portion 22 is located on the inside of 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 high laser energy, resulting in a large melting area. The interior of the explosion-proof valve 2 or the interior of the housing 1 receives low laser energy, resulting in a small melting area. As a result, the cross-sectional area of ​​the weld portion 21 gradually decreases from the surface of the explosion-proof valve 2 or the housing 1 inward, and the cross-section of the weld portion 21 is configured as a triangle. The larger the melting area of ​​the explosion-proof valve substrate, the greater the tensile stress generated by contraction 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 optional embodiments, the cross-sectional area of ​​the weld portion is configured as a rectangle, trapezoid, or parallelogram.

[0054] The buffer structure 3 is arranged close to the welding part 21 of the explosion-proof valve 2. The buffer structure 3 can be located on the shell 1, or the buffer structure 3 can also be located on the explosion-proof valve 2. By setting the buffer structure 3, the welding part 21 can release the tensile stress generated by the shrinkage process, thereby effectively reducing the influence of the welding part 21 on the thickness of the weak part 22 during the cooling and shrinkage process.

[0055] In the first embodiment provided in this application, Figures 2 to 6 As shown, the buffer structure 3 includes a first buffer groove 24 provided on the explosion-proof valve 2 , and the first buffer groove 24 is provided between the welding portion 21 and the weak portion 22 .

[0056] By adding a first buffer groove 24 to the explosion-proof valve 2, the welding portion 21 and the weak portion 22 are disconnected, and the base material of the welding portion 21 melts during the welding process and moves closer to one side of the shell 1. Then, during the cooling process of the welding portion 21 after welding, the internal stress generated by the cooling and shrinkage of the welding portion 21 is disconnected by the first buffer groove 24 and will not be transmitted to the weak portion 22, thereby effectively improving the influence of the stress generated by the cooling and shrinkage of the welding portion 21 after welding on the thickness of the weak portion 22.

[0057] In some embodiments, continue to refer to Figures 3 to 6 The explosion-proof valve 2 includes a first base portion 231 and a second base portion 232 connected to each other. The outer surface of the first base portion 231 is flush with the outer surface of the second base portion 232. The inner surface of the first base portion 231 is protruded inward relative to the inner surface of the second base portion 232, so that the thickness of the first base portion 231 is greater than the thickness of the second base portion 232.

[0058] The welding portion 21 and the first buffer groove 24 are both disposed on the first base portion 231 , wherein the first buffer groove 24 extends from the outer surface of the first base portion 231 to the inside of the first base portion 231 . The welding portion 21 is located on a side of the first base portion 231 away from the second base portion 232 .

[0059] The weak portion 22 is disposed on the second base portion 232 . The weak portion 22 includes a notch extending from the inner surface of the second base portion 232 to the interior of the second base portion 232 .

[0060] By arranging the welding portion 21 and the first buffer groove 24 on the first base portion 231 with a larger thickness, it is beneficial to maintain the overall structural strength of the explosion-proof valve 2. Arranging the weak portion 22 on the second base portion 232 with a thinner thickness is beneficial to the priority disconnection of the weak portion 22 when the pressure inside the battery 100 exceeds the preset high-pressure threshold.

[0061] Furthermore, the weak portion 22 extends from the inner surface of the second base portion 232 toward the outer surface, and the first buffer groove 24 extends inward from the outer surface of the first base portion 231, thereby forming a disconnected structure 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, which would affect the stability of the valve opening pressure of the explosion-proof valve 2. Furthermore, the heat of the weld 21 is concentrated on the outer surface of the first base portion 231. Therefore, the first buffer groove 24 is configured to extend from the outer surface of the first base portion 231 toward the inner surface. This allows the weld 21 to move closer to the housing 1 during the welding process, which facilitates stable welding between the explosion-proof valve 2 and the housing 1.

[0062] In some embodiments, as Figure 4 As shown, the width d1 of the first buffer groove 24 is set to 0.1 mm to 3.0 mm. In a specific embodiment, the width d1 of the first buffer groove 24 can be 0.1 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.6 mm, 1.9 mm, 2.0 mm, 2.3 mm, 2.5 mm, 2.6 mm, 2.8 mm, 3.0 mm, or a value between any two of the above values, or a range between any two of the above values.

[0063] The inventors discovered through research that when the width d1 of the first buffer groove 24 is set to less than 0.1 mm, the first buffer groove 24 is insufficiently wide, preventing a disconnection structure from being formed between the first buffer groove 24 and the weak portion 22. Consequently, the stress generated during the cooling and shrinkage of the welded portion 21 may still be transmitted to the weak portion 22 after passing through the first buffer groove 24. When the width d1 of the first buffer groove 24 is set to greater than 3.0 mm, the overall size of the first base portion 231 increases, which in turn increases the overall size of the explosion-proof valve 2, resulting in material waste and increased costs. This also makes it difficult to design the explosion-proof valve structure on the narrow sidewalls or top wall of the housing.

[0064] In some embodiments, continue to refer to Figure 4 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.

[0065] Through research, the inventors discovered that when the depth h1 of the first buffer groove 24 is set to less than 0.1 mm, the first buffer groove 24 is insufficiently deep, preventing a disconnection structure from being formed between the first buffer groove 24 and the weak portion 22. Consequently, the stress generated during the cooling and shrinkage of the weld portion 21 may still be transmitted to the weak portion 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 portion 231 is greater than 2 / 3, the thickness of the first base portion 231 where the first buffer groove 24 is located is relatively thin, resulting in insufficient strength of the first base portion 231, and even affecting the valve opening pressure of the explosion-proof valve 2.

[0066] In some embodiments, reference Figure 3 The width d2 of the welding portion 21 is set to 0.2 mm to 2 mm. In a specific implementation, the width d2 of the welding portion 21 can be 0.2 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.6 mm, 1.9 mm, 2.0 mm, or a value between any two of the above values, or a range between any two of the above values.

[0067] Through research, the inventors discovered that when the width d2 of the weld portion 21 is set to less than 0.2 mm, processing becomes difficult and a stable weld between the explosion-proof valve 2 and the housing 1 is formed. When the width d2 of the weld portion 21 is set to greater than 2.0 mm, the weld portion 21 may not be fully melted, affecting the weld quality between the explosion-proof valve 2 and the housing 1. Furthermore, the width d2 of the weld portion 21 is too close to the width d1 of the first buffer groove 24, so that the stress generated by the weld portion 21 during cooling cannot be fully buffered by the first buffer groove 24, thereby affecting the weak portion 22.

[0068] In the second embodiment provided in this application, Figures 7 to 11 As shown, the buffer structure 3 includes a second buffer groove 11 provided on the housing 1 . The second buffer groove 11 is located on a side of the welding portion 21 away from the weak portion 22 .

[0069] By adding a second buffer groove 11 to the shell 1, the second buffer groove 11 is arranged near the welding part 21. During the welding and cooling process of the base material of the welding part 21, the second buffer groove 11 can provide space for the deformation of the base material, so as to release the stress generated by welding without transmitting it to the weak part 22 near the welding part 21, thereby effectively improving the influence of the stress generated by the cooling shrinkage of the welding part 21 after welding on the thickness of the weak part 22.

[0070] In some embodiments, continue to refer to Figures 7 to 11As shown, the explosion-proof valve 2 includes a first base portion 231 and a second base portion 232 connected to each other. The outer surface of the first base portion 231 is flush with the outer surface of the second base portion 232, and the inner surface of the first base portion 231 is protruded inward relative to the inner surface of the second base portion 232, so that the thickness of the first base portion 231 is greater than the thickness of the second base portion 232.

[0071] The welding portion 21 is located on the first base portion 231 . The high temperature heat generated by the welding portion 21 during the welding process gradually decreases along the outer surface of the first base portion 231 toward the inside thereof.

[0072] The weak portion 22 is disposed on the second base portion 232 . The weak portion 22 is configured as a notch structure. The weak portion 22 extends from the inner surface of the second base portion 232 to the interior of the second base portion 232 .

[0073] The second buffer groove 11 of the shell 1 is arranged close to the welding part 21, and is located on both sides of the welding part 21 with the weak part 22. When the welding part 21 is in the welding process, 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, thereby effectively improving the stress generated by the welding part 21 during cooling after welding to be transferred to the weak part 22.

[0074] In some embodiments, as Figure 8b As shown, the width d3 of the second buffer groove 11 is set to 0.1mm-3.0mm. In a specific implementation, 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 a value between any two of the above values, or a range between any two of the above values.

[0075] The inventors discovered through research that when the width d3 of the second buffer groove 11 is set to less than 0.1 mm, the second buffer groove 11 is insufficiently wide, thereby failing to provide sufficient stress relief space. The stress generated during the cooling and shrinkage of the welded portion 21 may still be transmitted to the weak portion 22. When the width d3 of the second buffer groove 11 is set to greater than 3.0 mm, the overall structural strength of the housing 1 is compromised.

[0076] In some embodiments, continue to refer to Figure 4 , 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 shell 1 is not greater than 2 / 3.

[0077] Through research, the inventors discovered that when the depth h2 of the second buffer groove 11 is set to less than 0.1 mm, the second buffer groove 11 is insufficiently deep, thus failing to provide sufficient stress relief space. The stress generated during the cooling and shrinkage of the welded portion 21 may still be transmitted to the weak portion 22. When the ratio of the depth h2 of the second buffer groove 11 to the thickness of the housing 1 is greater than 2 / 3, the housing 1 where the second buffer groove 11 is located is thinner, thereby affecting the structural strength of the housing 1.

[0078] In the third embodiment provided in this application, Figures 12 to 14 As shown, the buffer structure 3 includes a buffer cavity 26, so that a height difference H is formed between the plane where the welding portion 21 is located and the plane where the weak portion 22 is located. The height difference H between the plane where the welding portion 21 is located and the plane where the weak portion 22 is located is set to be not less than 0.1 mm, and the height difference H between the plane where the welding portion 21 is located and the plane where the weak portion 22 is located is set to be not more than 2 mm.

[0079] In some embodiments, the height H between the plane where the welding portion 21 is located and the plane where the weak portion 22 is located can be 0.1 mm, 0.2 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.6 mm, 1.9 mm, 2.0 mm, and a value between any two of the above values ​​or a range between any two of the above values.

[0080] Since the plane where the weak portion 22 is located is staggered with the plane where the welding portion 21 is located, a buffer cavity 26 is formed between the plane where the weak portion 22 is located and the plane where the welding portion 21 is located. The buffer cavity 26 provides force release, and the stress generated by the welding portion 21 during welding and post-weld cooling is released in the buffer cavity 26 without being transmitted to the weak portion 22.

[0081] The inventors generally found through research that when the height difference H between the plane where the welding portion 21 is located and the plane where the weak portion 22 is located is set to less than 0.1 mm, the height of the stress release zone between the plane where the weak portion 22 is located and the plane where the welding portion 21 is located is insufficient, so that the stress generated by the welding portion 21 during welding and post-welding cooling can still be transmitted to the weak portion 22.

[0082] Furthermore, when the height difference H between the plane where the welding portion 21 is located and the plane where the weak portion 22 is located is set to be greater than 2 mm, the stress release area will occupy more space in the thickness direction of the shell 1, thereby reducing the structural strength of the shell 1.

[0083] In some embodiments, continue to refer to Figure 14As shown, the explosion-proof valve 2 includes a first base portion 231 and a second base portion 232 connected to each other. The inner surface of the first base portion 231 is flush with the inner surface of the second base portion 232, and the outer surface of the first base portion 231 is protruded relative to the outer surface of the second base portion 232. The welding 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 set as a notched structure, and the weak portion 22 extends from the inner surface of the second base portion 232 to the interior of the second base portion 232.

[0084] By arranging the outer surface of the first base portion 231 to be protruding relative to the outer surface of the second base portion 232 , it is beneficial to form a height difference structure between the welding portion 21 and the weak portion 22 .

[0085] In embodiment four provided in the present application, the buffer structure 3 includes a second buffer groove 11 structure arranged on the shell 1 and a height difference structure arranged between the plane where the welding 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 welding part 21, and a stress buffer zone is formed on the right side of the welding part 21. The stress generated by the welding part 21 during the welding and post-welding cooling process can be fully released into the second buffer groove 11 on its left side and the stress buffer zone on its right side, thereby effectively avoiding the stress from being transferred to the weak part 22.

[0086] In the above-mentioned embodiment provided in the present application, by staggering the plane where the weak portion 22 of the explosion-proof valve 2 is located and the outer surface where the welding portion 21 is located, or disconnecting the plane where the weak portion 22 of the explosion-proof valve 2 is located and the outer surface where the welding portion 21 is located, the stress generated by the welding portion 21 during welding and cooling after welding cannot be transmitted to the weak portion 22, thereby maintaining the stability of the overall thickness of the weak portion 22 and avoiding the welding process from affecting the thickness of the weak portion 22.

[0087] The plane where the weak portion is located is staggered from the outer surface of the welding portion, or the plane where the weak portion is located is disconnected from the outer surface of the welding portion.

[0088] In some embodiments, reference Figure 5 、 Figure 6 、 Figure 9 and Figure 10The explosion-proof valve 2 includes a first base portion 231 and a second base portion 232 connected to each other, and the weak portion 22 is located on the second base portion 232. The weak portion 22 includes a first score 221 and a second score 222, wherein the second score 222 is configured to extend from the inner surface of the second base portion 232 toward its outer surface, and the first score 221 extends from the bottom end surface of the second score 222 toward the outer surface of the second base portion 232. The first score 221 is configured as an unclosed ring, and a gap is formed between the two ends of the first score 221. The gap is configured as a portion of the second score 222, wherein the thickness of the first score 221 is smaller than the thickness of the second score 222.

[0089] When the pressure inside the battery 100 exceeds a preset threshold, the first notch 221 is disconnected first, and 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, which would cause the electrolyte inside the battery 100 to spray out through the large pressure relief opening and affect the safe use of the battery 100.

[0090] In some embodiments, as Figure 5 and Figure 10 As shown, a reinforcement portion 25 is provided on the second base portion 232. The thickness of the reinforcement portion 25 is greater than the thickness of the first notch 221. The reinforcement portion 25 includes three reinforcement segments. The head ends of the three reinforcement segments are all connected to the center of the second base portion 232, and the ends of the three reinforcement segments are connected to different positions of the first notch 221, thereby maintaining the overall structural strength of the explosion-proof valve 2.

[0091] In some embodiments, as Figure 5 and Figure 10 As shown, the second base portion 232 also includes a raised portion 27, which is arranged between the first notch 221 and the reinforcement portion 25. The raised portion 27 is arranged to be arched along the outer surface of the second base portion 232 toward its inner surface. By setting the area between the reinforcement portion 25 and the first notch 221 to be arched upward, the stability of the overall structure of the second base portion 232 of the explosion-proof valve 2 is enhanced, and it is beneficial to open the explosion-proof valve 2.

[0092] The above is a detailed introduction to the embodiments of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, based on the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A battery, characterized in that: include: case; An explosion-proof valve, comprising a welding portion welded to the housing, and further comprising a weak portion; The explosion-proof valve or the housing is provided with a buffer structure, and the buffer structure is provided close to the welding portion, and the buffer structure is used to release the stress generated by welding of the welding portion.

2. The battery according to claim 1, characterized in that The buffer structure includes a first buffer groove provided on the explosion-proof valve, wherein the first buffer groove is provided between the welding portion and the weak portion.

3. The battery according to claim 2, characterized in that The explosion-proof valve includes a first base portion and a second base portion surrounded by the first base portion, the outer surface of the first base portion is flush with the outer surface of the second base portion, and the inner surface of the first base portion is protruded inward relative to the inner surface of the second base portion; the first buffer groove is provided on the outer surface of the first base portion, the weak portion includes a notch, and the notch is provided on the inner surface of the second base portion, and the end of the first base portion away from the second base portion is the welding portion.

4. The battery according to claim 3, characterized in that The width of the first buffer groove is set to 0.1mm~3mm, and / or the depth of the first buffer groove is set to be greater than 0.1mm, and the ratio of the depth of the first buffer groove to the height of the first base part is not greater than 2 / 3; and / or the width of the welding part is set to 0.2mm~2mm.

5. The battery according to claim 1, characterized in that The buffer structure includes a second buffer groove provided on the shell, and the second buffer groove is located on a side of the welding portion away from the weak portion.

6. The battery according to claim 5, characterized in that The width of the second buffer groove is set to 0.1mm~3mm, and / or the depth of the second buffer groove is set to greater than 0.1mm, and the ratio between the depth of the second buffer groove and the thickness of the shell is not greater than 2 / 3; and / or the width of the welding part is set to 0.2mm~2mm.

7. The battery according to claim 1, characterized in that The buffer structure includes a buffer cavity arranged in the explosion-proof valve, so that a height difference is formed between the outer surface where the welding part is located and the outer surface where the weak part 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 according to claim 7, characterized in that The explosion-proof valve includes a first base portion and a second base portion surrounded by the first base portion, the inner surface of the first base portion is flush with the inner surface of the second base portion, and the outer surface of the first base portion is protruding outward relative to the outer surface of the second base portion; the buffer cavity is arranged on the outer surface of the second base portion, and the weak portion includes a notch, which is arranged on the inner surface of the second base portion.

9. The battery according to claim 5, characterized in that The buffer structure further includes a buffer cavity provided in the explosion-proof valve, so that a height difference is formed between the outer surface where the welding portion is located and the outer surface where the weak portion 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 according to claim 1, characterized in that The explosion-proof valve includes a first base portion and a second base portion connected to each other, the weak portion includes a first notch and a second notch, the second notch is arranged on the inner surface of the second base portion, the first notch is arranged on the inner surface of the second notch, and the first notch is arranged in an unclosed ring shape.

11. The battery according to claim 10, characterized in that A reinforcement portion is provided on the second base portion, and a thickness of the reinforcement portion is greater than a thickness of the second base portion where the first notch is located.

12. The battery according to claim 11, characterized in that The explosion-proof valve further includes a raised portion, the raised portion being located between the first notch and the reinforcement portion, and the raised portion being raised in a direction from the outer surface of the second base portion to the inner surface of the second base portion.

13. A battery pack, characterized in that: The battery pack includes a box and a plurality of batteries arranged inside the box, and the batteries include the batteries according to any one of claims 1 to 12.

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