A single cell and a battery pack

Abstract

The application discloses a single battery and a battery pack, and belongs to the technical field of batteries. The single battery comprises a shell, a containing cavity, and a through hole in communication with the containing cavity; an explosion-proof valve is connected with the shell and covers the through hole, and the explosion-proof valve comprises a skirt part, a first protruding part, a second protruding part, and a recessed part. The first protruding part and the second protruding part can be deformed to a certain extent, so that the protruding part of the first protruding part and the second protruding part is reduced and changes into a recessed part. When the recessed part is subjected to a relatively large force in the opposite direction of the recessed direction, the recessed part can also be deformed to a certain extent, so that the recessed part of the recessed part is reduced, and the recessed part changes into a protruding part. The structural change can also play a certain buffering role for the explosion-proof valve, avoid damage of the explosion-proof valve caused by a relatively large external force, improve the safety of the explosion-proof valve, and reduce the risk of abnormal cracking and early valve opening of the explosion-proof valve.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a single battery and a battery pack. BACKGROUND

[0002] The main function of the explosion-proof valve on the battery is pressure relief and gas exhaust, which is used for the directional release of high-temperature and high-pressure gas in the battery when the battery is in thermal runaway due to mechanical impact, internal abnormal interconnection short circuit and other reasons, so as to improve the safety performance of the battery pack. However, since the explosion-proof valve is in contact with the external environment, its structural strength is low, and the explosion-proof valve has a high risk of abnormal cracking and early valve opening under the action of external force. SUMMARY

[0003] The application aims to overcome the technical problem that the explosion-proof valve has a high risk of abnormal cracking and early valve opening under the action of external force. Another object of the application is to provide a battery pack.

[0004] TECHNICAL SOLUTION The single battery provided by the application comprises:

[0005] a shell having a containing cavity and a through hole in communication with the containing cavity;

[0006] an explosion-proof valve connected with the shell and covering the through hole, the explosion-proof valve comprising a skirt portion, a first protruding portion, a second protruding portion and a recessed portion, the recessed portion being arranged around the second protruding portion and connected with the second protruding portion, the first protruding portion being arranged around the recessed portion and connected with the recessed portion, the first protruding portion and the second protruding portion protruding in the same direction, i.e. in a first direction, the recessed portion being recessed in a direction opposite to the protruding direction of the first protruding portion, the skirt portion being arranged around the first protruding portion and connected with the first protruding portion, and an indentation being arranged at the connection between the first protruding portion and the skirt portion;

[0007] The single battery satisfies 0.21≤C / (A+B)≤0.34.

[0008] The bottom of the skirt portion is located on a reference plane, A is the distance from the top of the second protruding portion to the reference plane in the first direction, B is the distance from the top of the first protruding portion to the reference plane in the first direction, and C is the distance from the bottom of the recessed portion to the reference plane in the first direction.

[0009] In some embodiments, the protruding portion protrudes away from the containing cavity, and the explosion-proof valve comprises:

[0010] The first transition portion is arranged between the recess portion and the first protruding portion, and surrounds the recess portion, the first protruding portion surrounds the first transition portion, and the first transition portion comprises a first side surface, which is arranged away from the accommodating cavity and is a plane and perpendicular to the first direction;

[0011] The second protruding portion comprises a first connecting surface and a second connecting surface connected to each other, both of which are located on a side of the second protruding portion away from the accommodating cavity, the first connecting surface is arranged around the second connecting surface, the first connecting surface is an arc surface, and the second connecting surface is a plane and perpendicular to the first direction.

[0012] In some embodiments, the first transition portion comprises a second side surface, which is arranged opposite to the first side surface and is an arc surface.

[0013] In some embodiments, the first transition portion comprises a third side surface, which is arranged opposite to the first side surface and is a plane and perpendicular to the first direction.

[0014] In some embodiments, the second protruding portion comprises a third connecting surface, which is arranged toward the accommodating cavity and is an arc surface.

[0015] In some embodiments, the second protruding portion comprises a fourth connecting surface and a fifth connecting surface connected to each other, both of which are located on a side of the second protruding portion toward the accommodating cavity, the fourth connecting surface is arranged around the fifth connecting surface, the fourth connecting surface is an arc surface, and the fifth connecting surface is a plane and perpendicular to the first direction.

[0016] In some embodiments, the explosion-proof valve comprises:

[0017] A second transition portion is arranged around the first protruding portion, the first protruding portion is connected to the skirt portion through the second transition portion, and the score is arranged on the second transition portion.

[0018] The single battery satisfies L1≥t1 and L1≥t2.

[0019] Wherein, L1 is the thickness of the second transition portion, t1 is the thickness of the first protruding portion, and t2 is the thickness of the skirt portion.

[0020] In some embodiments, the single battery satisfies 0.15mm≤t=t≤0.2mm.

[0021] In some embodiments, the explosion-proof valve comprises a connecting portion, the connecting portion is arranged around the skirt portion, and the skirt portion is connected to the inner wall of the through hole through the connecting portion;

[0022] The monomer battery satisfies 0.4mm≤D≤0.6mm.

[0023] D is the thickness of the connecting portion in the first direction.

[0024] A battery pack comprising the monomer battery of any one of the above

[0025] Beneficial effects: The monomer battery of the embodiment comprises a shell having a receiving cavity and a through hole in communication with the receiving cavity; an explosion-proof valve connected to the shell and covering the through hole, the explosion-proof valve comprising a skirt portion, a first protruding portion, a second protruding portion and a recessed portion, the recessed portion being arranged around the second protruding portion and connected to the second protruding portion, the first protruding portion being arranged around the recessed portion and connected to the recessed portion, the protruding directions of the first protruding portion and the second protruding portion being the same, both being arranged in the first direction, the recessed direction of the recessed portion being opposite to the protruding direction of the first protruding portion, the skirt portion being arranged around the first protruding portion and connected to the first protruding portion, and the connecting portion between the first protruding portion and the skirt portion being provided with a notch; the monomer battery satisfies 0.21≤C / (A+B)≤0.34; wherein the plane where the bottom of the skirt portion is located is the reference plane, A is the distance from the top of the second protruding portion to the reference plane in the first direction, B is the distance from the top of the first protruding portion to the reference plane in the first direction, and C is the distance from the bottom of the recessed portion to the reference plane in the first direction. By arranging the first protruding portion, the second protruding portion and the recessed portion with arc-shaped surfaces, external forces can be effectively transmitted to the foundation or support structure, which can protect the explosion-proof valve to a certain extent. At the same time, when the first protruding portion and the second protruding portion are subjected to a larger force in the opposite direction of the protruding direction, the first protruding portion and the second protruding portion can deform to a certain extent, so that the protruding part of the first protruding portion and the second protruding portion decreases, and the recessed part changes into a protruding part. When the recessed portion is subjected to a larger force in the opposite direction of the recessed direction, the recessed portion can also deform to a certain extent, so that the recessed part of the recessed portion decreases, and the recessed part changes into a protruding part. The change in structure can also play a certain buffering role for the explosion-proof valve, avoiding damage to the explosion-proof valve due to the action of a larger external force, improving the safety of the explosion-proof valve, and reducing the risk of abnormal cracking and early opening of the explosion-proof valve. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0027] Figure 1 It is a perspective view of the shell of the embodiment of the present application;

[0028] Figure 2 It is a sectional perspective view of the shell of the embodiment of the present application;

[0029] Figure 3 It is a front sectional view of the shell of the embodiment of the present application;

[0030] Figure 4 It is an enlarged view of the area A in the embodiment of the present application; Figure 3

[0031] Figure 5 It is a perspective view of the explosion-proof valve of the embodiment of the present application;

[0032] Figure 6 It is a front sectional view of the explosion-proof valve of the embodiment of the present application, wherein the second side surface on the first transition part is an arc surface;

[0033] Figure 7 It is a front sectional view of the second protruding part of the embodiment of the present application, wherein the third connecting surface is an arc surface;

[0034] Figure 8 It is a front sectional view of the explosion-proof valve of the embodiment of the present application, wherein the third side surface on the first transition part is a plane;

[0035] Figure 9 It is a front sectional view of the explosion-proof valve of the embodiment of the present application, wherein the second protruding part has a fourth connecting surface and a fifth connecting surface;

[0036] Figure 10 It is a front sectional view of the second protruding part of the embodiment of the present application, wherein the fourth connecting surface is an arc surface and the fifth connecting surface is a plane;

[0037] Figure 11 It is a front sectional view of the explosion-proof valve of the embodiment of the present application, wherein the explosion-proof valve has a second transition part;

[0038] ​10 - housing; 11 - accommodating cavity; 12 - through hole; 20 - explosion-proof valve; 21 - skirt portion; 22 - first protruding portion; 23 - second protruding portion; 231 - first connecting surface; 232 - second connecting surface; 233 - third connecting surface; 234 - fourth connecting surface; 235 - fifth connecting surface; 24 - recessed portion; 25 - score; 26 - first transition portion; 261 - first side surface; 262 - second side surface; 263 - third side surface; 27 - second transition portion; 28 - connecting portion; 30 - reference surface; X - first direction. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without creative labor fall within the scope of protection of the present application.

[0040] In the description of the present application, it should be understood that the terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, at least one of which can be one, two or more, unless otherwise specifically limited.

[0041] The main function of the explosion-proof valve on the battery is to release pressure and exhaust gas. It is used for the directional release of high-temperature and high-pressure gas inside the battery when the battery is in thermal runaway due to mechanical impact, internal abnormal lap joint short circuit, etc., thereby improving the safety performance of the battery pack. At present, the monomer battery is gradually thinned in design, which leads to the gradual reduction of the size of the explosion-proof valve. How to reasonably set the structure of the explosion-proof valve in the limited length and width, so that the valve opening value meets the design requirements, improves the structural strength, and reduces the risk of abnormal cracking and early valve opening when it is subjected to external force, is a technical problem to be solved at present.

[0042] Therefore, the embodiments of the present application provide a monomer battery to overcome at least one of the above technical problems.

[0043] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 In the embodiments of the present application, the monomer battery comprises a housing 10 and an explosion-proof valve 20.

[0044] The shell 10 has a containing cavity 11 and a through hole 12 communicating with the containing cavity 11. The explosion-proof valve 20 is connected with the shell 10 and covers the through hole 12. The explosion-proof valve 20 comprises a skirt part 21, a first protruding part 22, a second protruding part 23 and a recessed part 24. The recessed part 24 is arranged around and connected with the second protruding part 23. The first protruding part 22 is arranged around and connected with the recessed part 24. The protruding directions of the first protruding part 22 and the second protruding part 23 are the same, both protruding in the first direction X. The recessed direction of the recessed part 24 is opposite to the protruding direction of the first protruding part 22. The skirt part 21 is arranged around and connected with the first protruding part 22. The connection part of the first protruding part 22 and the skirt part 21 is provided with a notch 25.

[0045] It can be understood that the explosion-proof valve 20 on the single battery is generally arranged on the cover plate of the battery. However, due to the thinner and thinner design of the battery, the width of the cover plate connected to one side of the battery shell 10 is also smaller and smaller. This results in that the width of the explosion-proof valve 20 originally arranged on the cover plate is limited, and the explosion-proof valve 20 cannot be well arranged on the cover plate, which may cause the opening valve value of the explosion-proof valve 20 to fail to meet the design requirements of the battery. Therefore, in the present application, the explosion-proof valve 20 originally arranged on the cover plate of the battery is arranged on the shell 10 of the battery (for example Figure 1 ), and the width of the shell 10 of the battery is generally greater than or equal to the width of the cover plate (at least part of the cover plate needs to be embedded into the containing cavity 11 of the shell 10, so as to reduce the space occupied by the cover plate. Therefore, the width of the cover plate is generally less than or equal to the width of the shell 10. The explosion-proof valve 20 can also be arranged on other sides of the shell 10. Arranging the explosion-proof valve 20 on the shell 10 can provide a larger arrangement space for the explosion-proof valve 20, without limiting the width and length of the explosion-proof valve 20, so as to meet the design of the structure size of the explosion-proof valve 20 and ensure that the explosion-proof valve 20 can normally open.

[0046] Meanwhile, when the explosion-proof valve 20 is arranged on the shell 10, and the opening valve value of the explosion-proof valve 20 meets the design requirements, the first protruding part 22 can be arranged on the explosion-proof valve 20, the first protruding part 22 is arranged in the first direction X (in the first direction X, the first protruding part 22 is arranged protruding from the skirt part 21), the surface of the first protruding part 22 is at least partially arc-shaped, when an external force opposite to the protruding direction of the first protruding part 22 acts on the first protruding part 22, the force acting on the first protruding part 22 is effectively transmitted to the foundation or the supporting structure through the first protruding part 22, that is, to the skirt part 21, and the skirt part 21 is connected with the shell 10, so that part of the force is transmitted to the shell 10. Moreover, when the first protruding part 22 is subjected to a larger force opposite to the protruding direction, the first protruding part 22 can be deformed to a certain extent, so that the protruding part of the first protruding part 22 is reduced and changes into a recessed part (the protruding part of the first protruding part 22 can be partially changed into a recessed part, or completely changed into a recessed part), and the change of the structure can play a certain buffering role for the explosion-proof valve 20, avoid damage of the first protruding part 22 caused by a larger force, and improve the safety. The recessed part 24 is arranged on the inner side of the first protruding part 22, the first protruding part 22 surrounds the recessed part 24, the surface of the recessed part 24 is at least partially arc-shaped, and the recessed direction of the recessed part 24 is opposite to the protruding direction of the first protruding part 22. When an external force opposite to the recessed direction of the recessed part 24 acts on the recessed part 24, the force acting on the recessed part 24 can be effectively transmitted to the foundation or the supporting structure through the recessed part 24, that is, to the first protruding part 22, and the first protruding part 22 is connected with the shell 10 through the skirt part 21, so that part of the force is transmitted to the shell 10. Moreover, when the recessed part 24 is subjected to a larger force opposite to the recessed direction, the recessed part 24 can also be deformed to a certain extent, so that the recessed part of the recessed part 24 is reduced, and the recessed part changes into a protruding part (the recessed part of the recessed part 24 can be partially changed into a protruding part, or completely changed into a protruding part), and the change of the structure can also play a certain buffering role for the explosion-proof valve 20, avoid damage of the recessed part 24 caused by a larger force, and improve the safety. Meanwhile, the second protruding part 23 is arranged on the inner side of the recessed part 24, the recessed part 24 surrounds the second protruding part 23, the surface of the second protruding part 23 is at least partially arc-shaped, the protruding direction of the second protruding part 23 is opposite to the recessed direction of the recessed part 24, and the protruding direction of the second protruding part 23 is the same as the protruding direction of the first protruding part 22. When an external force opposite to the protruding direction of the second protruding part 23 acts on the second protruding part 23, part of the force acting on the second protruding part 23 can be effectively transmitted to the recessed part 24 and the first protruding part 22 through the second protruding part 23, so that part of the force is transmitted to the shell 10.When the second protruding part 23 is subjected to a large force in the direction opposite to the protruding direction, the second protruding part 23 can be deformed to a certain extent, so that the protruding part of the second protruding part 23 is reduced, and the protruding part is changed into a recessed part (the protruding part of the second protruding part 23 can be partially changed into a recessed state, or completely changed into a recessed state). The change of the structure can also play a certain buffering role for the explosion-proof valve 20, avoid damage of the second protruding part 23 due to a large force, and improve the safety.

[0047] The single battery satisfies: 0.21≤C / (A+B)≤0.34; wherein, the plane where the bottom of the skirt part 21 is located is the reference surface 30, A is the distance from the top of the second protruding part 23 to the reference surface 30 in the first direction X, B is the distance from the top of the first protruding part 22 to the reference surface 30 in the first direction X, and C is the distance from the bottom of the recessed part 24 to the reference surface 30 in the first direction X. It can be understood that the value of C / (A+B) in the range of 0.21 to 0.34 (including 0.21 and 0.34) can be: any numerical value in 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34 or a range value between any two numerical values. When in this range, the pressure resistance of the first protruding part 22, the recessed part 24 and the second protruding part 23 can be effectively improved under the condition that the preset opening valve value of the explosion-proof valve 20 is satisfied, and the structural strength of the first protruding part 22, the recessed part 24 and the second protruding part 23 can be ensured to a certain extent (the first protruding part 22, the recessed part 24 and the second protruding part 23 form the main part of the explosion-proof valve 20, and improving the structural strength of the first protruding part 22, the recessed part 24 and the second protruding part 23 can improve the structural strength of the explosion-proof valve 20), avoiding damage or early opening of the valve when the first protruding part 22, the recessed part 24 and the second protruding part 23 are subjected to external pressure. The values of A, B and C can be measured by a caliper or a three-dimensional scanner. It should be noted that when testing the explosion-proof valve 20 in the embodiment of the present application, multiple groups of batteries with the explosion-proof valve 20 are tested (the value of C / (A+B) on each group of explosion-proof valves 20 is different), and a force of 0.4 Mpa can be applied to the explosion-proof valve 20 along the first direction X, and whether the first protruding part 22, the recessed part 24 and the second protruding part 23 are broken or not is observed. The test results of the examples and comparative examples are as follows:

[0048]

[0049]

[0050] As can be seen from the above table, when a certain force is applied to the first protruding portion 22, the recessed portion 24 and the second protruding portion 23 along the first direction X, no rupture occurs to the first protruding portion 22, the recessed portion 24 and the second protruding portion 23 when the value of C / (A+B) is in the range of 0.21 to 0.34 (including 0.21 and 0.34), which indicates that the first protruding portion 22, the recessed portion 24 and the second protruding portion 23 have good pressure resistance in this case, and the risk of abnormal cracking and early valve opening of the explosion-proof valve 20 can be reduced. When the value of C / (A+B) is less than 0.21, rupture occurs to at least one of the first protruding portion 22, the recessed portion 24 and the second protruding portion 23. In this case, the recessed portion 24 has a relatively large recess degree (that is, the value of C is small), so that the curvature of the arch-shaped structure formed by the recessed portion 24 is too large, and the stability of the arch-shaped structure is reduced, and the pressure resistance is reduced, so that rupture may occur when the arch-shaped structure is subjected to force. When the value of C / (A+B) is greater than 0.34, rupture occurs to at least one of the first protruding portion 22, the recessed portion 24 and the second protruding portion 23. In this case, the recessed portion 24 has a relatively small recess degree (that is, the value of C is large), so that the curvature of the arch-shaped structure formed by the recessed portion 24 is too small, and the support effect of the arch-shaped structure is reduced, and the pressure resistance is reduced, so that rupture may occur when the arch-shaped structure is subjected to force.

[0051] Please refer to Figure 6 and Figure 7 , in combination with the above embodiments, in some embodiments, the first protruding portion 22 is arranged to protrude away from the accommodation cavity 11, and the explosion-proof valve 20 comprises a first transition portion 26.

[0052] The first transition portion 26 is arranged between the recessed portion 24 and the first protruding portion 22, and surrounds the recessed portion 24, the first protruding portion 22 surrounds the first transition portion 26, and the first transition portion 26 comprises a first side surface 261, the first side surface 261 is arranged to protrude away from the accommodation cavity 11, the first side surface 261 is a plane, and is perpendicular to the first direction X.

[0053] The second protruding portion 23 comprises a first connecting surface 231 and a second connecting surface 232 connected to each other, the first connecting surface 231 and the second connecting surface 232 are located on the side of the second protruding portion 23 away from the accommodation cavity 11, the first connecting surface 231 is arranged to surround the second connecting surface 232, the first connecting surface 231 is an arc surface, and the second connecting surface 232 is a plane and is perpendicular to the first direction X.

[0054] It can be understood that the first transition portion 26 is arranged between the first protruding portion 22 and the recessed portion 24, and the side of the first transition portion 26 away from the accommodating cavity 11 is a first side surface 261, and the first side surface 261 is arranged in a planar structure. Meanwhile, the side of the second protruding portion 23 away from the accommodating cavity 11 has a first connecting surface 231 and a second connecting surface 232, wherein the first connecting surface 231 is an arc surface and extends towards the direction away from the accommodating cavity 11, so that the second protruding portion 23 is in a convex state, and the second connecting surface 232 is a planar surface, and the first connecting surface 231 is arranged around the second connecting surface 232. The height of the second connecting surface 232 is the same as the maximum height of the first connecting surface 231, and the height of the second connecting surface 232 can be greater than or equal to the height of the first side surface 261. Therefore, when the main body portion of the explosion-proof valve 20 is subjected to an external force (the force is relatively uniform and perpendicular to the second connecting surface 232), the external force will first act on the second connecting surface 232 or the second connecting surface 232 and the first side surface 261. Since the second connecting surface 232 and the first side surface 261 are planar surfaces, the planar structure has a larger force receiving area than the arc surface structure (wherein the surface of the external object in contact with the main body portion of the explosion-proof valve 20 is also planar), which can provide a larger planar area to disperse the local load. This structure can distribute the load more evenly to the entire explosion-proof valve 20 through the planar surface, avoiding the problem of local stress concentration of the main body portion of the explosion-proof valve 20 (the main body portion of the explosion-proof valve includes the first protruding portion 22, the second protruding portion 23 and the recessed portion 24), which can cause the explosion-proof valve 20 to be easily damaged.

[0055] Please refer to Figure 6 , in combination with the above embodiments, in some embodiments, the first transition portion 26 includes a second side surface 262, the second side surface 262 is arranged opposite to the first side surface 261, and the second side surface 262 is an arc surface.

[0056] It can be understood that the first transition part 26 has two surfaces arranged opposite to each other in the first direction X, one is the first side surface 261 arranged as a planar structure, and the first side surface 261 is arranged at the top of the first transition part 26, and the other is the second side surface 262 arranged as an arc surface, and the second side surface 262 is arranged at the bottom of the first transition part 26. The second side surface 262 is arranged towards the accommodating cavity 11 of the battery, and when the battery is in thermal runaway, a large amount of gas is generated in the interior of the accommodating cavity 11, the gas enters the through hole 12, and the explosion-proof valve 20 is extruded, and because the second side surface 262 on the explosion-proof valve 20 is an arc surface, the second side surface 262 has a larger contact area with the gas generated in the interior of the battery, so that the extrusion force of the gas on the second side surface 262 in a unit of time is larger, thereby causing the main body part of the explosion-proof valve 20 to be torn at the position of the notch 25 in time, the explosion-proof valve 20 can be opened in time to release pressure, and the safety of the battery is ensured, and explosion of the battery caused by too late opening of the explosion-proof valve 20 is avoided.

[0057] Please refer to Figure 8 , in combination with the above embodiment, in some embodiments, the first transition part 26 includes a third side surface 263, the third side surface 263 is arranged opposite to the first side surface 261, and the third side surface 263 is a planar surface and is perpendicular to the first direction X.

[0058] It can be understood that the first transition part 26 has two surfaces arranged opposite to each other in the first direction X, one is the first side surface 261 arranged as a planar structure, and the first side surface 261 is arranged at the top of the first transition part 26, and the other is the second side surface 262 arranged as an arc surface, and the second side surface 262 is arranged at the bottom of the first transition part 26. The second side surface 262 is arranged towards the accommodating cavity 11 of the battery, and when the battery is in thermal runaway, a large amount of gas is generated in the interior of the accommodating cavity 11, the gas enters the through hole 12, and the explosion-proof valve 20 is extruded, and because the second side surface 262 on the explosion-proof valve 20 is an arc surface, the second side surface 262 has a larger contact area with the gas generated in the interior of the battery, so that the extrusion force of the gas on the second side surface 262 in a unit of time is larger, thereby causing the main body part of the explosion-proof valve 20 to be torn at the position of the notch 25 in time, the explosion-proof valve 20 can be opened in time to release pressure, and the safety of the battery is ensured, and explosion of the battery caused by too late opening of the explosion-proof valve 20 is avoided.

[0059] Please refer to Figure 6 、 Figure 7 and Figure 8In some embodiments, the second protruding portion 23 comprises a third connecting surface 233, which is arranged towards the accommodating cavity 11, and the third connecting surface 233 is an arc surface.

[0060] It can be understood that the third connecting surface 233 of the second protruding portion 23 arranged towards the accommodating cavity 11 is an arc surface. When thermal runaway occurs inside the battery, a large amount of gas will be generated inside the accommodating cavity 11, which will press the explosion-proof valve 20. Since the third connecting surface 233 of the explosion-proof valve 20 is an arc surface, it has a larger contact area with the gas generated inside the battery, so that the extrusion force of the gas on the third connecting surface 233 in unit time is larger, thereby causing the main body portion of the explosion-proof valve 20 to be torn at the position of the notch 25 in time, and the explosion-proof valve 20 can be opened in time to release pressure, further improving the safety of the battery and avoiding the explosion of the battery caused by the explosion-proof valve 20 opening too late.

[0061] Please refer to Figure 9 and Figure 10 In some embodiments, the second protruding portion 23 comprises a fourth connecting surface 234 and a fifth connecting surface 235 connected to each other, the fourth connecting surface 234 and the fifth connecting surface 235 are both located on the side of the second protruding portion 23 facing the accommodating cavity 11, the fourth connecting surface 234 is arranged around the fifth connecting surface 235, the fourth connecting surface 234 is an arc surface, the fifth connecting surface 235 is a plane, and the fifth connecting surface 235 is perpendicular to the first direction X.

[0062] It can be understood that the fourth connecting surface 234 and the fifth connecting surface 235 are arranged on the side of the second protruding portion 23 facing the accommodating cavity 11, the fourth connecting surface 234 is an arc surface, and the fifth connecting surface 235 is a plane. The position of the fourth connecting surface 234 corresponds to the position of the first connecting surface 231 in the first direction X, and the shape and area of the fourth connecting surface 234 are substantially the same as those of the first connecting surface 231. The position of the fifth connecting surface 235 corresponds to the position of the second connecting surface 232 in the first direction X, and the shape and area of the fifth connecting surface 235 are substantially the same as those of the second connecting surface 232. The purpose of this structure is to make the thickness of the second protruding portion 23 more uniform, avoid the thickness of a certain part of the second protruding portion 23 being too thin and the strength being too low, and the part being easily broken under external force; and also avoid the thickness of a certain part of the second protruding portion 23 being too large, thereby increasing the processing cost and difficulty of the second protruding portion 23.

[0063] Please refer to Figure 11 In some embodiments, the explosion-proof valve 20 comprises:

[0064] The second transition portion 27 is arranged around the first protruding portion 22, the first protruding portion 22 is connected with the skirt portion 21 through the second transition portion 27, and the score 25 is arranged on the second transition portion 27. The single battery satisfies L1≥t1 and L1≥t2. Wherein, L1 is the thickness of the second transition portion 27, t1 is the thickness of the first protruding portion 22, and t2 is the thickness of the skirt portion 21.

[0065] It can be understood that the second transition portion 27 is arranged between the first protruding portion 22 and the skirt portion 21, the second transition portion 27 is arranged around the first protruding portion 22, the skirt portion 21 is arranged around the second transition portion 27, and the score 25 is arranged on the second transition portion 27. Meanwhile, the thickness L1 of the second transition portion 27 is arranged to be larger, which needs to be greater than or equal to the thickness t1 of the first protruding portion 22 and the thickness t2 of the skirt portion 21 (since the score 25 is arranged on the second transition portion 27, the thickness of the second transition portion 27 can be arranged to be larger). When the score 25 is arranged on the second transition portion 27, the depth range of the score 25 can be arranged to be larger, and then the value range of the opening valve value of the explosion-proof valve 20 can be arranged to be wider, so that the explosion-proof valve 20 can be applied to different battery pressure relief requirements, and the applicability of the explosion-proof valve 20 is improved.

[0066] Please refer to Figure 11 , in combination with the above embodiment, in some embodiments, the single battery satisfies 0.15mm≤t1=t2≤0.2mm.

[0067] It can be understood that when the thickness t1 of the first protruding portion 22 and the thickness t2 of the skirt portion 21 are equal and in the range of 0.15mm to 0.2mm (including 0.15mm and 0.2mm), the explosion-proof valve 20 has better uniformity, which is beneficial to the setting of the opening valve value of the explosion-proof valve 20, and ensures that the opening valve value will not have a large deviation. Meanwhile, when t1 and t2 are in the range of 0.15mm to 0.2mm, the explosion-proof valve 20 can open in time. When the values of t1 and t2 are less than 0.15mm, the thickness of the first protruding portion 22 and the thickness of the skirt portion 21 are small, and when the battery has thermal runaway, the explosion-proof valve 20 may open in advance; when the values of t1 and t2 are greater than 0.2mm, the thickness of the first protruding portion 22 and the thickness of the skirt portion 21 are large, and when the battery has thermal runaway, even if the pressure in the battery reaches the preset pressure, the explosion-proof valve 20 may not open, so that the pressure relief of the explosion-proof valve 20 is delayed.

[0068] Please refer to Figure 11 , in combination with the above embodiment, in some embodiments, the explosion-proof valve 20 includes a connecting portion 28, the connecting portion 28 is arranged around the skirt portion 21, and the skirt portion 21 is connected with the inner wall of the through hole 12 through the connecting portion 28;

[0069] The monomer battery satisfies: 0.4mm≤D≤0.6mm;

[0070] D is the thickness of the connecting portion 28 in the first direction X.

[0071] It can be understood that the skirt portion 21 is connected with the inner wall of the through hole 12 through the connecting portion 28, and the thickness of the connecting portion 28 is in the range of 0.4mm to 0.6mm (including 0.4mm and 0.6mm), when the thickness of the connecting portion 28 is in the range, the connecting portion 28 has a larger area to connect with the inner wall of the through hole 12, which can ensure the stability of the connection between the connecting portion 28 and the inner wall of the through hole 12. When the thickness of the connecting portion 28 is less than 0.4mm, the connecting area between the connecting portion 28 and the inner wall of the through hole 12 is small, the stability of the connection is low, and the difficulty of the connection is increased, which is not recommended. When the thickness of the connecting portion 28 is greater than 0.6mm, the connecting portion 28 has a larger connecting area with the inner wall of the through hole 12, but the volume of the connecting portion 28 is large, the space occupied is more, and the processing cost is also increased, which is not recommended.

[0072] A battery pack comprising the monomer battery described above. The battery pack has all the technical features and beneficial effects of the monomer battery described above, which will not be described in detail here.

[0073] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0074] The monomer battery and the battery pack provided by the embodiments of the present application are described in detail above, and specific examples are applied to describe the principles and implementation modes of the present application. The above description of the embodiments is only used to help understand the technical solutions and core ideas of the present application; those skilled in the art should understand that they can still modify the technical solutions recorded in the above embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A single cell, characterized by, The shell has a containing cavity and a through hole communicating with the containing cavity. The explosion-proof valve is connected with the shell and covers the through hole, the through hole is not on the cover plate, the explosion-proof valve comprises a skirt part, a first protruding part, a second protruding part and a recessed part, the recessed part is arranged around the second protruding part and is connected with the second protruding part, the first protruding part is arranged around the recessed part and is connected with the recessed part, the protruding directions of the first protruding part and the second protruding part are the same, and the first protruding part and the second protruding part are arranged in the first direction, the recessed direction of the recessed part is opposite to the protruding direction of the first protruding part, the skirt part is arranged around the first protruding part and is connected with the first protruding part, an indentation is arranged at the connection between the first protruding part and the skirt part, and the first protruding part, the second protruding part and the recessed part are all arc structures. The single battery satisfies 0.21<=C / (A+B)<=0.

34. The bottom of the skirt part is on a reference plane, A is the distance from the top of the second protruding part to the reference plane in the first direction, B is the distance from the top of the first protruding part to the reference plane in the first direction, C is the distance from the bottom of the recessed part to the reference plane in the first direction, and the first direction is the penetrating direction of the through hole. The first protruding part protrudes away from the containing cavity, and the explosion-proof valve comprises:

2. The cell according to claim 1, wherein A first transition part is arranged between the recessed part and the first protruding part and surrounds the connection of the recessed part, the first protruding part surrounds the connection of the first transition part, the first transition part comprises a first side surface, the first side surface is arranged away from the containing cavity, and the first side surface is a plane and is perpendicular to the first direction. The second protruding part comprises a first connecting surface and a second connecting surface connected with each other, the first connecting surface and the second connecting surface are located on the side of the second protruding part away from the containing cavity, the first connecting surface surrounds the second connecting surface, the first connecting surface is an arc surface, and the second connecting surface is a plane and is perpendicular to the first direction. The first transition part comprises a second side surface, the second side surface is arranged opposite to the first side surface, and the second side surface is an arc surface.

3. The cell according to claim 2, wherein The first transition part comprises a third side surface, the third side surface is arranged opposite to the first side surface, the third side surface is a plane and is perpendicular to the first direction.

4. The cell according to claim 2, wherein The second protruding part comprises a third connecting surface, the third connecting surface is arranged towards the containing cavity, and the third connecting surface is an arc surface.

5. The cell according to claim 2, wherein The second protruding part comprises a fourth connecting surface and a fifth connecting surface connected with each other, the fourth connecting surface and the fifth connecting surface are located on the side of the second protruding part towards the containing cavity, the fourth connecting surface surrounds the fifth connecting surface, the fourth connecting surface is an arc surface, and the fifth connecting surface is a plane and is perpendicular to the first direction.

6. The cell according to claim 2, wherein The explosion-proof valve comprises:

7. The cell according to claim 1, wherein ​ A second transition portion is arranged around the first protruding portion, the first protruding portion is connected with the skirt portion through the second transition portion, and the score is arranged on the second transition portion; The single battery satisfies: L1≥t1, and L1≥t2; Wherein, L1 is the thickness of the second transition portion, t1 is the thickness of the first protruding portion, and t2 is the thickness of the skirt portion.

8. The cell according to claim 1, wherein The single battery satisfies: 0.15mm≤t1=t2≤0.2mm.

9. The cell according to claim 1, wherein The explosion-proof valve comprises a connecting portion, the connecting portion is arranged around the skirt portion, and the skirt portion is connected with the inner wall of the through hole through the connecting portion; The single battery satisfies: 0.4mm≤D≤0.6mm; Wherein, D is the thickness of the connecting portion in the first direction.

10. A battery pack, characterized by, The single battery comprises a single battery as claimed in any one of claims 1 to 9.

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