A battery case, a single battery, and a battery module

Abstract

The utility model discloses a battery case, include: casing and end cover, the end of casing along the first direction forms the opening, and the casing includes the first department and thickening portion of integral connection, and the first department and thickening portion arrange in proper order along the first direction at the opening, and the thickness of thickening portion is greater than the thickness of first department, makes the first department and thickening portion between form first step surface, the end cover covers in the opening of casing and is supported by first step surface, and the end cover is fused welding fixed with casing, and its molten pool hits thickening portion, in the battery case, the position of casing and end cover contact is designed as the bayonet structure, and the welding mark track position of end cover and casing is formed in thickening portion, and the combination of both can improve the mechanical property of battery case, can also reduce the vibration amplitude of end cover, prevent the rupture of battery case caused by vibration, guarantee safety, the utility model discloses a single battery and battery module.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, specifically relating to a battery casing, a single battery cell, and a battery module. Background Technology

[0002] In the manufacturing process of single-cell batteries, the reliability of the battery casing is a crucial issue. In existing technologies, a battery casing typically consists of a housing and end caps. After the end caps are inserted into the opening of the housing, a laser is usually used as a heat source to melt the lateral contact surfaces of the end caps and housing, thus welding them together. However, during vibration testing of single-cell batteries, cracks easily appear at the weld lines between the end caps and housing, leading to battery casing damage. Utility Model Content

[0003] The purpose of this utility model is to disclose a battery casing that can improve the mechanical properties of the battery casing, reduce the vibration amplitude of the end cap, prevent vibration from causing the battery casing to break, and improve safety.

[0004] To achieve the above objectives, this utility model discloses a battery casing, comprising:

[0005] The shell has an opening at its end along a first direction. The shell includes an integrally connected first part and a thickened part. The first part and the thickened part are arranged sequentially along the first direction at the opening. The thickness of the thickened part is greater than the thickness of the first part, so that a first stepped surface is formed between the first part and the thickened part.

[0006] The end cap fits into the opening of the shell and is supported by the first stepped surface. The end cap is welded to the shell and its molten pool extends to the thickened part.

[0007] As an optional implementation, the first stepped surface is inclined, and the angle between the first stepped surface and the first direction is between 45° and 60°.

[0008] As an optional implementation, the thickness of the first part is A, and the thickness of the thickened part is B, satisfying A*1.2≤B≤A*1.4.

[0009] As an optional implementation, the end cap includes an integrally connected cover portion and an extension portion, the cover portion and the extension portion being arranged sequentially along a first direction, a second stepped surface being formed between the cover portion and the extension portion, the cover portion being embedded inside the first portion, the extension portion being embedded inside the thickened portion, and the first stepped surface supporting the second stepped surface.

[0010] As an optional implementation, along the first direction, the depth dimension of the extension is less than or equal to the depth dimension of the thickened portion.

[0011] As an optional implementation, the depth dimension of the extension along the first direction is C, which satisfies 1.2mm≤C≤1.6mm.

[0012] As an alternative implementation, the edge of the extension away from the cover is also chamfered.

[0013] As an optional implementation, the housing also includes a body portion integrally connected to the end of the thickened portion away from the first portion. The outer surfaces of the first portion, the thickened portion, and the body portion are flush, and the inner surfaces of the first portion and the body portion are flush. The thickened portion protrudes inward to thicken.

[0014] Based on the same technical concept, a single battery cell is also disclosed, which includes the aforementioned battery casing and battery core, with the battery core disposed within a receiving cavity formed by the casing and end cap.

[0015] Based on the same technical concept, a battery module was also disclosed, which uses the aforementioned single battery cell.

[0016] Compared with the prior art, the advantages of the battery casing, single battery cell, and battery module of this utility model are as follows:

[0017] The casing is thickened by the thickening section, and a first stepped surface is formed between the first section and the thickening section to support the end cap. When the end cap is welded to the casing, the molten pool is made to hit the thickening section. In this way, the contact position between the casing and the end cap is designed as a bayonet structure, and the welding trace of the end cap and the casing is formed in the thickening section. The combination of the two can improve the mechanical properties of the battery casing and reduce the vibration amplitude of the end cap, prevent vibration from causing the battery casing to break, and ensure safety. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a partial cross-sectional schematic diagram of a single cell of this utility model.

[0020] Figure 2 yes Figure 1 The enlarged view of part F shown.

[0021] Explanation of key figure labels:

[0022] 1. Shell; 11. First part; 12. Thickened part; 13. Body part; 14. First stepped surface; 15. Third stepped surface; 2. End cap; 21. Cover part; 22. Extension part; 221. Chamfer; 23. Second stepped surface; 3. Molten pool; 4. Insulating component. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0025] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model according to the specific circumstances.

[0026] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0027] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0028] The technical solution of this utility model will be further described below with reference to the embodiments and accompanying drawings.

[0029] In existing technology, the casing includes a housing and an end cap. The housing has an opening, and the end cap closes the opening. To facilitate the positioning of the end cap, a step is generally provided on the inner side of the opening of the housing. The step is used to support the end cap to complete the positioning and assembly of the end cap before welding, and then the end cap is welded and fixed to the housing. However, the inventors of this application discovered in their research that the high temperature during the welding of the end cap and the housing can easily cause a heat-affected zone to form on the part of the end cap and the housing near the welding trajectory. The strength of the part of the end cap and the housing in the heat-affected zone is low. Furthermore, since the fusion welding area between the end cap and the housing is often located above the step, cracks can easily occur at the welding trajectory between the end cap and the housing during vibration testing of a single battery, during charging and discharging of the battery module, during excessive gas generation in the battery core, or during thermal runaway, leading to damage to the battery casing and thus reducing the service life and reliability of the single battery and the battery module.

[0030] In view of this, the inventors provide a battery casing, a single battery cell, and a battery module to improve the above-mentioned technical problems. The battery casing includes a housing 1 and an end cap 2, the end cap 2 covering the opening of the housing 1; the single battery cell includes a battery casing and a battery core, the battery core being disposed within a receiving cavity formed by the housing 1 and the end cap 2; the battery module utilizes multiple single batteries.

[0031] Please see Figure 1 As shown, the housing 1 serves as a load-bearing component, and its shape can be cylindrical or rectangular, etc. The end cap 2 corresponds to the shape of the housing 1. The materials of the housing 1 and the end cap 2 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., to achieve fusion welding between the two. Functional components such as electrode terminals and insulating parts 4 can be provided on the end cap 2. An opening is formed at the end of the housing 1 along the first direction. The housing 1 includes a first part 11, a thickened part 12, and a body part 13 integrally connected, wherein the body part 13 serves as the main body of the housing 1. The first part 11 is connected to one end of the thickened part 12, and the body part 13 is connected to the other end of the thickened part 12. With the orientation of the opening as a reference, the first part 11 The first part 11 and the thickened part 12 are arranged sequentially along the first direction at the opening. The first part 11 is closer to the opening of the housing 1 than the thickened part 12. The thickness of the thickened part 12 is greater than the thickness of the first part 11, so that a first stepped surface 14 is formed between the first part 11 and the thickened part 12. The main function of the first stepped surface 14 is to facilitate the positioning and assembly of the end cap 2. The thickness of the thickened part 12 is also greater than the thickness of the body part 13, so that a third stepped surface 15 is formed between the thickened part 12 and the body part 13. The main function of the third stepped surface 15 is to form a transition to avoid stress concentration. The end cap 2 is closed to the opening of the housing 1 and supported by the first stepped surface 14. The end cap 2 is welded to the housing 1, and its molten pool 3 is welded to the thickened part 12.

[0032] Specifically, with Figure 2With the direction shown as a reference, the first part 11, the thickened part 12 and the main body part 13 are arranged from top to bottom, so that the first stepped surface 14 faces upward, so as to support the end cover 2 using the first stepped surface 14.

[0033] The aforementioned first direction refers to the opening direction of the housing 1. Taking a cylindrical housing as an example, the opening of the housing 1 is at its axial end, and the first direction is the axial direction of the housing 1. Taking a rectangular housing as an example, the opening of the housing 1 is at its upper height, and the first direction is the height direction of the housing 1. Figure 2 The directions shown are for reference only; they are specifically represented by up and down directions.

[0034] The molten pool 3 during the welding of the end cap 2 and the shell 1 reaches the thickened portion 12, so as to... Figure 2 The direction shown is for reference, meaning that the molten pool 3 covers the first part 11, the first stepped surface 14 and at least part of the thickened part 12 from top to bottom.

[0035] It should also be noted that the shell 1 may have an opening at only one end, or the shell 1 may have openings at both ends. When it is open at both ends, the structure of the first part 11 and the thickened part 12 described above can be formed at either end of the shell 1, or the structure of the first part 11 and the thickened part 12 described above can be formed at both ends of the shell 1, depending on the specific needs.

[0036] In the above scheme, the shell 1 is thickened by the thickening part 12, and a first stepped surface 14 is formed between the first part 11 and the thickening part 12. During assembly, the end cap 2 is inserted into the opening of the shell 1 until it is supported by the first stepped surface 14, and the end cap 2 is positioned. Then, a laser welding device is used to heat and weld the contact point between the end cap 2 and the shell 1, and the molten pool 3 is controlled to hit the thickening part 12, so that the molten pool 3 covers the first part 11, the first stepped surface 14 and at least part of the thickening part 12. In this way, the contact point between the shell 1 and the end cap 2 is designed as a bayonet structure, thereby reducing the risk of the end cap 2 collapsing, and the welding trace of the end cap 2 and the shell 1 is formed in the thickening part 12. The combination of the two can improve the mechanical performance of the battery shell, reduce the vibration amplitude of the end cap 2, prevent vibration from causing the battery shell to break, ensure safety, and improve the service life and reliability of the single cell and the battery module.

[0037] In some embodiments, the thickening portion 12 can be provided in multiple segments and arranged at intervals along the circumference of the opening of the housing 1, or it can be arranged around the opening of the housing 1. In some rectangular housings 1, since the stress of vibration or expansion acts more on the two opposite sidewalls with larger areas in the housing 1, the thickening portion 12 can also be provided only on the two opposite sidewalls with larger areas in the housing 1 to specifically solve the problem that the large surface of the rectangular housing 1 is more prone to cracking.

[0038] See Figure 2 In some embodiments, the first stepped surface 14 can be inclined or perpendicular to the first direction. The inclined arrangement of the first stepped surface 14 can be understood as the first stepped surface 14 forming an angle less than 90° with the first direction, thereby facilitating the assembly guidance and positioning of the end cap 2, while also providing support for the end cap 2. More preferably, the angle between the first stepped surface 14 and the first direction is between 45° and 60°. The significance of this angle range is that: when forming the molten pool 3 through welding, an excessively small angle would result in a deeper overall depth of the molten pool 3 when it reaches the thickened portion 12. To avoid affecting the battery core, the end cap 2 would need to be made thicker, leading to an excessively large battery casing 1 and consequently reducing the energy density of the individual battery cells; an excessively large angle would cause the first stepped surface 14 to hinder the smooth assembly of the end cap 2, affecting production efficiency.

[0039] See Figure 2 In some embodiments, the inner surfaces of the first part 11 and the body part 13 are flush, and the outer surfaces of the first part 11, the thickened part 12, and the body part 13 are flush. The end face of the cover part 21 away from the extension part 22 is flush with the end face of the first part 11 away from the thickened part 12. That is, the upper surface of the end cap 2 is flush with the upper surface of the housing 1. The first part 11 and the body part 13 have equal thicknesses, the thickened part 12 protrudes inward and thickens, and a third stepped surface 15 is formed between the body part 13 and the thickened part 12. In this solution, while satisfying the requirement for the thickened part 12, it also ensures that the outer surface of the housing 1 is smooth and regular. Furthermore, since the first part 11 and the body part 13 have equal thicknesses, on the one hand, the overall strength of the housing 1 can be guaranteed, and on the other hand, the weight of the housing 1 can be effectively controlled, reducing the impact on the energy density of the individual battery. Since the upper surface of the end cap 2 is flush with the upper surface of the housing 1.

[0040] In other embodiments, the first part 11 and the thickened part 12 may be arranged in a circumferentially outward manner relative to the main body part 13, such that the inner surfaces of the thickened part 12 and the main body part 13 are flush, and the outer surfaces of the first part 11 and the thickened part 12 are flush. In this case, the third stepped surface 15 formed between the main body part 13 and the thickened part 12 will be on the outer side.

[0041] In some embodiments, the third step surface 15 is preferably inclined, that is, the third step surface 15 forms an angle of less than 90° with the first direction. More preferably, the angle between the third step surface 15 and the first direction is between 45° and 60°. The significance of the inclined third step surface 15 is that during vibration testing, or during the charging and discharging process of the battery module, or when the amount of gas generated in the battery core is large, or during thermal runaway, when the stress of vibration or expansion is transmitted to the connection between the body part 13 and the thickened part 12, the inclined third step surface 15 can disperse the stress, avoid stress concentration, and further improve reliability.

[0042] See Figure 1 and Figure 2 To adapt the end cap 2 to the housing 1, in some embodiments, the end cap 2 includes an integrally connected closing portion 21 and an extension portion 22, the closing portion 21 and the extension portion 22 being arranged sequentially along a first direction, and a second stepped surface 23 being formed between the closing portion 21 and the extension portion 22. Figure 2 With the indicated direction as a reference, the extension 22 is connected to the lower part of the cover 21. During assembly, the end cap 2 is inserted into the housing 1 from top to bottom, so that the cover 21 is embedded inside the first part 11, and the extension 22 is embedded inside the thickened part 12. The first stepped surface 14 supports the second stepped surface 23, thereby completing the assembly of the end cap 2 for subsequent welding operations. Preferably, the edge of the extension 22 away from the cover 21 is also provided with a chamfer 221. The chamfer 221 can be a rounded corner or an angled corner. The use of the chamfer 221 is to guide the extension 22 to be more smoothly embedded inside the thickened part 12. Combined with the guiding and supporting role of the first stepped surface 14 and the second stepped surface 23, the assembly of the end cap 2 on the housing 1 is smoother.

[0043] See Figure 2 In some embodiments, along the first direction, the depth dimension of the extension 22 is less than or equal to the depth dimension of the thickened portion 12. This is significant because the molten pool 3 is less likely to melt through the thickened portion 12 during the welding operation, and ensures that the heat-affected zone of the molten pool 3 does not expand to the entire thickened portion 12 or even to the third stepped surface 15. This allows a portion of the thickened portion 12 or a large portion of the third stepped surface 15 to retain greater strength after welding, further improving the overall mechanical properties of the battery casing.

[0044] See Figure 2 In some embodiments, the end cap 2 is further provided with an insulating member 4, which protrudes from the end face of the extension 22 and extends into the interior of the housing 1, so as to... Figure 2The direction shown is for reference, that is, the insulating part 4 is located below the end cap 2, the insulating part 4 extends downward into the interior of the housing 1, and the insulating part 4 can be used to press against the inner core of the battery; in the circumferential direction of the opening, there is a gap between the insulating part 4 and the thickened part 12, so as to avoid the heat radiation of the molten pool 3 hitting the thickened part 12 affecting the insulating part 4.

[0045] See Figure 2 In some embodiments, the thickness of the first part 11 is A, and the thickness of the thickened part 12 is B, satisfying A*1.2≤B≤A*1.4. Based on the aforementioned equal thickness of the first part 11 and the main body 13, the thickness A is the original wall thickness of the shell 1 in the prior art. Controlling the thickness B of the thickened part 12 to be greater than or equal to 1.2 times the thickness A, while being less than or equal to 1.2 times the thickness A, has the following significance: on the one hand, it makes the thickened part 12 have higher strength; on the other hand, the thickened part 12 occupies less circumferential space in the opening, so that the single battery cell can have a higher energy density.

[0046] See Figure 2 In some embodiments, the depth dimension of the extension 22 along the first direction is C, satisfying 1.2mm≤C≤1.6mm. Since the molten pool 3 needs to reach the thickened portion 12, it also needs to reach the extension 22. By controlling the depth dimension of the extension 22 to be between 1.2mm and 1.6mm, it is ensured that the molten pool 3 can grip the thickened portion 12 and the extension 22, preventing cracking. It also facilitates demolding of the shell 1 during the manufacturing process, making manufacturing easier.

[0047] In summary, the battery casing, individual battery, and battery module of this utility model thicken the casing 1 through the thickening part 12, use the first stepped surface 14 to support and position the end cap 2, and control the molten pool 3 to strike the thickening part 12, so that the molten pool 3 covers the first part 11, the first stepped surface 14, and at least part of the thickening part 12. This can improve the mechanical properties of the battery casing and reduce the vibration amplitude of the end cap 2, preventing vibration from causing the battery casing to break, ensuring safety, and improving the service life and reliability of the individual battery and battery module. Through the guidance and support of the first stepped surface 14 at a specific tilt angle, and the chamfer 221, the battery casing 1 is further improved. The guide ensures precise and smooth assembly and positioning of the end cap 2 and the housing 1; by controlling the depth dimension of the extension 22 in the end cap 2 to not exceed the depth dimension of the thickened part 12, it ensures that the heat-affected zone of the molten pool 3 will not expand to the entire thickened part 12 or even to the third stepped surface 15, so that a portion of the thickened part 12 or a large portion of the third stepped surface 15 retains significant strength after welding; by controlling the thickness dimension and depth dimension of the thickened part 12, it ensures that the thickened part 12 has high strength, that the single cell can have high energy density, and that it is easy to process and demold.

[0048] The technical means disclosed in this utility model are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications are also considered within the scope of protection of this utility model.

Claims

1. A battery casing, characterized in that, include: The housing has an opening at one end along a first direction. The housing includes an integrally connected first part and a thickened part. The first part and the thickened part are arranged sequentially along the first direction at the opening. The thickness of the thickened part is greater than the thickness of the first part, so that a first stepped surface is formed between the first part and the thickened part. An end cap, which covers the opening of the housing and is supported by the first stepped surface, is welded to the housing and its molten pool extends to the thickened portion.

2. The battery casing according to claim 1, characterized in that, The first stepped surface is inclined, and the angle between the first stepped surface and the first direction is between 45° and 60°.

3. The battery casing according to claim 1, characterized in that, The thickness of the first part is A, and the thickness of the thickened part is B, satisfying A*1.2≤B≤A*1.

4.

4. The battery casing according to any one of claims 1 to 3, characterized in that, The end cap includes an integrally connected cover portion and an extension portion. The cover portion and the extension portion are arranged sequentially along the first direction. A second stepped surface is formed between the cover portion and the extension portion. The cover portion is embedded inside the first portion, and the extension portion is embedded inside the thickened portion. The first stepped surface supports the second stepped surface.

5. The battery casing according to claim 4, characterized in that, Along the first direction, the depth dimension of the extension is less than or equal to the depth dimension of the thickened portion.

6. The battery casing according to claim 4, characterized in that, Along the first direction, the depth dimension of the extension is C, which satisfies 1.2mm≤C≤1.6mm.

7. The battery casing according to claim 4, characterized in that, The edge of the extension away from the cover is also chamfered.

8. The battery casing according to any one of claims 1 to 3, characterized in that, The housing also includes a body portion integrally connected to the end of the thickened portion away from the first portion. The outer surfaces of the first portion, the thickened portion, and the body portion are flush, and the inner surfaces of the first portion and the body portion are flush. The thickened portion protrudes inward and thickens.

9. A single-cell battery, characterized in that, It includes a battery casing and a battery core as described in any one of claims 1-8, wherein the battery core is disposed within a receiving cavity formed by the casing and the end cap.

10. A battery module, characterized in that, The application includes the single-cell battery as described in claim 9.

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