Battery case and battery cell

Abstract

The application discloses a battery shell and a battery monomer, and relates to the technical field of batteries. The battery shell comprises a shell, a cover plate and a welding mark structure. The shell comprises a side plate, the side plate is surrounded to form a containing cavity, and the side plate has opposite inner and outer walls and a top wall connected between the inner and outer walls. The cover plate has opposite top and bottom surfaces and a side surface connected between the top and bottom surfaces, and the bottom surface of the cover plate is arranged towards the top wall of the side plate. Part of the side plate and part of the cover plate are fused to form the welding mark structure to connect the side plate and the cover plate. The welding mark structure has a first connecting point on the outer wall and a second connecting point at the deepest position in the shell or the cover plate. The connecting line of the first connecting point and the second connecting point forms an angle alpha with the outer wall of the side plate, and alpha satisfies alpha > 90 DEG. The battery shell can improve the performance of the heat-affected zone in bearing internal pressure, thereby improving the welding strength and welding reliability of the battery shell.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery casing and a battery cell. Background Technology

[0002] With the rapid development of the new energy industry, energy storage systems and new energy vehicles are placing increasingly stringent demands on battery performance and safety. As a crucial component of the battery, the structural stability and sealing performance of the battery casing directly affect its lifespan and safety. The weld between the outer casing and the cover plate is a key structural element of the battery casing. The welding quality at this point not only affects the battery's sealing effect but also withstands significant stress under conditions such as internal pressure changes, making it a core element in ensuring safe battery operation. Laser welding technology, due to its high welding precision, is used in battery production to achieve sealing and structural fixation between the outer casing and the cover plate.

[0003] In existing technologies, during laser welding, a heat-affected zone (HAZ) forms in the area corresponding to the weldment structure. The material in the HAZ is affected by high temperatures, causing changes in its crystal structure and a decrease in strength after recrystallization. In other words, the structural strength of the HAZ is lower than that of the base material and the weldment structure, respectively. Furthermore, since the structural strength of the side panels of the casing is lower than that of the cover plate, the HAZ has a significant impact on the structural strength of the side panels. When the internal pressure of the battery increases, the HAZ located on the side panels may fracture under the influence of this internal pressure, and the fracture path of the side panels extends along their thickness, thereby reducing the welding strength and reliability of the battery casing. Utility Model Content

[0004] This application provides a battery casing and a battery cell that can improve the performance of the heat-affected zone in withstanding internal pressure, thereby improving the welding strength and welding reliability of the battery casing, and at least partially solving the above-mentioned technical problems.

[0005] To achieve the above objectives, according to a first aspect of this application, a battery casing is provided, comprising: The housing includes side panels that surround a receiving cavity, the side panels having opposing inner and outer walls and a top wall connecting the inner and outer walls; A cover plate having opposing top and bottom surfaces and a side surface connecting the top and bottom surfaces, the bottom surface of the cover plate being disposed facing the top wall of the side plate; A solder joint structure is formed by melting a portion of the side plate and a portion of the cover plate to connect the side plate and the cover plate. The solder joint structure has a first connection point located on the outer wall and a second connection point located at the deepest point inside the outer shell or the cover plate. Wherein, the line connecting the first connection point and the second connection point forms an angle α with the outer wall of the side plate, satisfying: α>90°.

[0006] Optionally, the angle α between the line connecting the first connection point and the second connection point and the outer wall of the side plate satisfies: 120°≤α≤160°.

[0007] Optionally, the second connection point is located on the cover plate; Wherein, the maximum depth of the solder mark structure is greater than or equal to the thickness of the side plate.

[0008] Optionally, the second connection point is located on the side plate; The maximum depth of the solder mark structure is less than the thickness of the side plate.

[0009] Optionally, the maximum depth of the solder mark structure is 0.5-0.9 times the thickness of the side plate.

[0010] Optionally, the solder mark structure may further have a third connection point located on the side or top surface of the cover plate.

[0011] Optionally, the normal of the second connection point divides the solder pattern into a first part and a second part, the first part extending away from the outer casing and the second part extending toward the outer casing; Wherein, the melt volume of the first part is less than or equal to the melt volume of the second part.

[0012] Optionally, the battery housing further includes a boss, which is disposed on the bottom surface of the cover and extends toward the receiving cavity.

[0013] Optionally, the battery housing further includes a seal disposed between the boss and the inner wall of the side plate.

[0014] According to a second aspect of this application, a battery cell is provided, comprising an inner core and a battery housing as described in any of the preceding claims, wherein the inner core is mounted within a receiving cavity of the battery housing.

[0015] Beneficial Effects: Compared with the prior art, the battery casing and battery cell of this application embodiment include a shell and a cover plate. The shell and cover plate are connected by a welded structure, and a heat-affected zone is formed in the area corresponding to the welded structure. Since the structural strength of the welded structure is greater than that of the heat-affected zone, in the prior art, the third side of the welded structure forms an angle α with the outer wall of the side plate, where α < 90°. When the battery casing is subjected to internal pressure, the fracture path of the side plate extends along the thickness direction of the side plate. In this application, by setting the cover plate on the top of the side plate, and the line connecting the first connection point and the second connection point forms an angle α with the outer wall of the side plate, satisfying α > 90°, when the battery casing is subjected to internal pressure, the fracture path of the side plate extends along the inclined direction of the line connecting the first connection point and the second connection point. Compared with the prior art, this application changes the extension direction of the fracture path of the side plate, which can lengthen the fracture path and is equivalent to increasing the area of ​​the heat-affected zone. This can improve the performance of the heat-affected zone in withstanding internal pressure, thereby improving the welding strength and welding reliability of the battery casing.

[0016] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0019] Figure 1 This is a schematic diagram of the structure of a battery cell provided in an exemplary embodiment of this disclosure; Figure 2 yes Figure 1 A partially enlarged structural schematic diagram of one embodiment at point A; Figure 3 This is a partially enlarged structural diagram of another battery cell provided in an exemplary embodiment of this disclosure; Figure 4 This is a partially enlarged structural diagram of a single battery cell in existing technology; Figure 5 This is a schematic diagram of the structure of a single battery cell in the prior art; Figure 6 yes Figure 5 A magnified schematic diagram of the structure at point B in the middle.

[0020] Explanation of reference numerals in the attached figures: 100. Battery casing; 1. Outer shell; 11. Side plate; 111. Inner wall; 112. Outer wall; 113. Top wall; 12. Receiving cavity; 13. Bottom plate; 2. Cover plate; 21. Top surface; 22. Bottom surface; 23. Side surface; 3. Seam; 4. Welded structure; 41. First side; 42. Second side; 43. Third side; 44. First part; 45. Second part; 46. First connection point; 47. Second connection point; 48. Third connection point; 5. Boss; 6. Seal; 7. Heat-affected zone; 200. Inner core. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to up, down, left, and right in the actual use or working state of the device, specifically the drawing directions in the accompanying drawings.

[0022] In this application, unless otherwise expressly specified and limited, the terms "connected," "linked," "stacked," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] This application provides a battery casing and a battery cell, which are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0024] Reference Figure 1One embodiment of this application provides a battery cell, including a battery casing 100 and an inner core 200. The battery casing 100 has a receiving cavity 12, and the inner core 200 is installed within the receiving cavity 12 of the battery casing 100. The battery cell can have a square structure, a cylindrical structure, etc. Correspondingly, the battery casing 100 and the inner core 200 can have a square structure, a cylindrical structure, etc. In this application, a cylindrical structure of the battery cell is used as an example for description. The battery casing 100 may include an outer shell 1 and a cover plate 2. The cover plate 2 and the outer shell 1 are connected by welding, such as laser welding or resistance welding. In this application, the connection between the cover plate 2 and the outer shell 1 by laser welding is used as an example for description.

[0025] The outer shell 1 and cover plate 2 of the battery casing 100 can be made of metal, such as steel, aluminum, or aluminum alloy. The structural design of the battery casing 100 needs to be customized according to the battery type and installation space. Metal has good processing performance and can be processed into complex shapes through various processes such as stamping, stretching, bending, and welding, resulting in high production efficiency and ensuring dimensional accuracy. Metal has high tensile strength, yield strength, and hardness, providing a robust protective casing for the battery cells, effectively resisting external impacts, compression, and vibration, reducing the risk of deformation or breakage of the battery casing 100, preventing damage to the internal structure of the battery cells, and reducing the risk of short circuits or leakage. The metal battery casing 100 can withstand the pressure generated by the internal gas during the charging and discharging of the battery cells, preventing the battery casing 100 from expanding, deforming, or breaking. The metal battery casing 100 can quickly conduct the heat generated by the charging and discharging of the battery cells, and can also form an efficient heat dissipation path in conjunction with a heat dissipation system, helping to achieve a more uniform temperature distribution in all areas of the battery casing 100, avoiding localized overheating, and extending the service life of the battery cells. Metals have high melting points and good corrosion resistance, and can maintain structural stability even in extreme environments.

[0026] Specifically, refer to Figure 1The outer casing 1 may include side plates 11, which enclose a receiving cavity 12. The side plates 11 have opposing inner walls 111 and outer walls 112, and a top wall 113 connecting the inner walls 111 and outer walls 112. The inner walls 111 of the side plates 11 face the receiving cavity 12, and the outer walls 112 of the side plates 11 face away from the receiving cavity 12. At least one end of the outer casing 1 is open. In this embodiment, one end of the outer casing 1 is open, and the other end of the outer casing 1 has a bottom plate 13, which, together with the side plates 11, encloses the receiving cavity 12. The side plates 11 and the bottom plate 13 may be separate structures, connected together by welding or other methods, such as laser welding. Alternatively, the side plates 11 and the bottom plate 13 may be integrally formed. As a preferred embodiment, the side plate 11 and the bottom plate 13 are integrally formed. This not only improves the connection strength and sealing between the side plate 11 and the bottom plate 13, but also eliminates the need for welding or other methods to connect the side plate 11 and the bottom plate 13, reducing the production process of the outer shell 1, thereby reducing the production cost and improving the production efficiency of the outer shell 1. At the same time, it can also improve the dimensional accuracy of the outer shell 1, reduce assembly errors, and thus improve the fitting accuracy between the outer shell 1 and the cover plate 2.

[0027] Reference Figure 1 and Figure 2 The outer diameter of the cover plate 2 is larger than the inner diameter of the outer shell 1 to ensure that the cover plate 2 can be disposed on the top wall 113 of the side plate 11. Furthermore, the outer diameter of the cover plate 2 is preferably equal to or approximately equal to the outer diameter of the outer shell 1. This not only facilitates the installation and alignment of the cover plate 2 and the outer shell 1 but also facilitates welding between the cover plate 2 and the outer shell 1, thereby improving welding effect and efficiency. Specifically, the cover plate 2 has opposing top surfaces 21 and bottom surfaces 22, and a side surface 23 connecting the top surface 21 and the bottom surface 22. The bottom surface 22 of the cover plate 2 faces the receiving cavity 12 and the top wall 113 of the side plate 11, while the top surface 21 of the cover plate 2 faces away from the receiving cavity 12. The bottom surface 22 of the cover plate 2 faces the top wall 113 of the side plate 11, and a joint 3 is formed between the bottom surface 22 of the cover plate 2 and the top wall 113 of the side plate 11. The joint 3 is, for example, the fitting clearance between the cover plate 2 and the side plate 11, and the size of the joint 3 can be zero or greater than zero. Laser welding can be performed from the outer wall 112 of the side plate 11 and the side 23 of the cover plate 2 to weld the side plate 11 and the cover plate 2 together.

[0028] Reference Figure 1 and Figure 2A portion of the side plate 11 and a portion of the cover plate 2 are melted to form a weldment structure 4, connecting the side plate 11 and the cover plate 2. After laser welding, the weldment structure 4 can fill at least a portion of the joint 3 to form a sealed connection between the cover plate 2 and the side plate 11. The weldment structure 4 has a first connection point 46 located on the outer wall 112 and a second connection point 47 located at the deepest point inside the outer casing 1 or the cover plate 2. The weldment structure 4 can be formed by laser welding, which melts a portion of the side plate 11 and a portion of the cover plate 2 on both sides of the joint 3 to form a molten pool. After the molten pool cools, the weldment structure 4 is formed. The weldment structure 4 extends from the surface of the battery casing 100 into the interior of the battery casing 100. During the laser welding process, a heat-affected zone 7 (e.g., ...) is formed in the area corresponding to the weldment structure 4. Figures 2 to 4 As shown in the dashed box in the diagram, the heat-affected zone 7 is adjacent to the solder mark structure 4. The heat-affected zone 7 refers to the area of ​​the base material that, during the welding process, is heated but has not reached its melting point. Its microstructure and mechanical properties change due to the high temperature. The material in the heat-affected zone 7 is affected by the high temperature, causing changes in its crystal structure and a decrease in strength after recrystallization. Therefore, the structural strength of the heat-affected zone 7 is less than that of both the base material and the solder mark structure 4. When the battery casing 100 is subjected to internal pressure, the heat-affected zone 7 will fracture first.

[0029] As an example, the side plate 11 of the outer shell 1 and the cover plate 2 can be made of the same material. The thickness of the side plate 11 is thinner than that of the cover plate 2. Therefore, the structural strength of the side plate 11 is less than that of the cover plate 2. As a result, the heat-affected zone 7 has a greater impact on the structural strength of the side plate 11 of the outer shell 1, and also makes the side plate 11 more prone to breakage.

[0030] Among them, reference Figure 2 and Figure 3 The line connecting the first connection point 46 and the second connection point 47 forms an angle α with the outer wall 112 of the side plate 11, satisfying α > 90°. The angle α between the line connecting the first connection point 46 and the second connection point 47 and the outer wall 112 of the side plate 11 can be any value among 95°, 105°, 115°, 120°, 135°, 145°, 155°, 165°, 175°, or any value between any two. Preferably, the angle α between the line connecting the first connection point 46 and the second connection point 47 and the outer wall 112 of the side plate 11 satisfies 120° ≤ α ≤ 160°, which ensures welding strength while facilitating the implementation of the laser welding process.

[0031] The shape of the solder joint structure 4 can be adjusted by adjusting the laser trajectory, thereby adjusting the angle α formed between the line connecting the first connection point 46 and the second connection point 47 and the outer wall 112 of the side plate 11. The overall structure of the solder joint structure 4 can be roughly conical or approximately conical. The outer edge of the solder joint structure 4 can be regular or irregular in shape due to the welding process or the material of the battery casing 100. In this embodiment, for better explanation, the outer edge of the solder joint structure 4 is described as having a regular shape, that is, the cross-section of the solder joint structure 4 is triangular.

[0032] As an example, the cross-section of the solder joint structure 4 can be composed of a first side 41, a second side 42, and a third side 43. The first side 41 is located on the outer wall 112 of the side plate 11 and the side surface 23 of the cover plate 2. The second side 42 is located near the cover plate 2, and the third side 43 is located near the side plate 11. In this case, the intersection of the first side 41 and the third side 43 coincides with the first connection point 46, the intersection of the second side 42 and the third side 43 coincides with the second connection point 47, and the third side 43 coincides with the line connecting the first connection point 46 and the second connection point 47. The third side 43 forms an angle α with the outer wall 112 of the side plate 11, satisfying that α > 90°. It should be noted that the dashed box in the figure of this application indicates the heat-affected zone 7 near the third side 43, and the heat-affected zone 7 is not absolutely distributed according to the dashed box. The dashed box is used to indicate the distribution trend of the heat-affected zone 7.

[0033] In this application, the battery casing 100 includes an outer shell 1 and a cover plate 2. The outer shell 1 and the cover plate 2 are connected by a welded structure 4. A heat-affected zone 7 is formed in the area corresponding to the welded structure 4. Since the structural strength of the welded structure 4 is greater than the structural strength of the heat-affected zone 7, in the prior art, referring to... Figures 4 to 6 The line connecting the first connection point 46 and the second connection point 47 forms an angle α with the outer wall 112 of the side plate 11, that is, the third side 43 of the solder mark structure 4 forms an angle α with the outer wall 112 of the side plate 11, where α < 90° (e.g., Figure 4 and Figure 6 As shown), when the battery casing 100 is subjected to internal pressure, the fracture path of the side plate 11 will extend along the thickness direction of the side plate 11 (e.g. Figure 4 and Figure 6 (As shown by the dashed line with arrows). This application involves placing the cover plate 2 on top of the side plate 11, and the third side 43 of the solder structure 4 forming an angle α with the outer wall 112 of the side plate 11, satisfying: α > 90° (e.g., ...). Figure 2 and Figure 3 As shown), when the battery casing 100 is subjected to internal pressure, the fracture path of the side plate 11 will extend along the inclined direction of the third side 43 (as shown). Figure 2 and Figure 3(As shown by the dashed line with arrows), compared with the prior art, this application changes the extension direction of the fracture path of the side plate 11, which can lengthen the fracture path and is equivalent to increasing the area of ​​the heat-affected zone 7. This can improve the performance of the heat-affected zone 7 in withstanding internal pressure, thereby improving the welding strength and welding reliability of the battery casing 100. It should be noted that the fracture path of the side plate 11 in this application does not extend absolutely in the direction shown in the figure, but rather represents the extension trend of the fracture path of the side plate 11.

[0034] In one specific implementation, refer to Figure 2 The connection point between the second side 42 and the third side 43 can be located on the cover plate 2, or it can be located on the side plate 11. The connection point between the second side 42 and the third side 43 can be the lowest point of the weldment structure 4, that is, the intersection of the second side 42 and the third side 43, representing the maximum depth of the weldment structure 4. In other words, the intersection of the second side 42 and the third side 43 is the second connection point 47. The depth of the weldment structure 4 can be adjusted as needed, and can be controlled by adjusting the laser welding parameters.

[0035] Reference Figure 2 When the intersection of the second side 42 and the third side 43 is located on the cover plate 2, that is, when the second connection point 47 is located on the cover plate 2, the maximum depth of the solder joint structure 4 can be greater than or equal to the thickness of the side plate 11. This ensures that the solder joint structure 4 has sufficient depth, thereby ensuring the stability of the connection between the cover plate 2 and the side plate 11. In some embodiments, when the intersection of the second side 42 and the third side 43 is located on the cover plate 2, the maximum depth of the solder joint structure 4 can also be less than the thickness of the side plate 11.

[0036] Reference Figure 3 When the intersection of the second side 42 and the third side 43 is located on the side plate 11, that is, when the second connection point 47 is located on the side plate 11, the maximum depth of the weld mark structure 4 is preferably less than the thickness of the side plate 11. This prevents the side plate 11 from being welded through, ensuring the connection strength of the weld and preventing spatter or oxide residue from entering the interior of the battery casing 100 during welding. The maximum depth of the weld mark structure 4 is preferably 0.5-0.9 times the thickness of the side plate 11. While preventing the side plate 11 from being welded through, it also ensures that the weld mark structure 4 has sufficient structural strength, thereby ensuring the stability of the connection between the side plate 11 and the cover plate 2, and thus improving the welding yield and quality.

[0037] In some embodiments, the weldment structure 4 further has a third connection point 48 located on the side 23 or the top surface 21 of the cover plate 2. The third connection point 48 can be the intersection of the first side 41 and the second side 42. The first side 41 extends from the side 23 of the cover plate 2 to a portion of the top surface 21 of the cover plate 2. This not only increases the contact area between the weldment structure 4 and the cover plate 2, helping to improve the weld strength and thus ensuring the stability of the connection between the side plate 11 and the cover plate 2, but also improves the sealing performance between the side plate 11 and the cover plate 2. At the same time, the welding status of the cover plate 2 can be visually inspected, thereby achieving stability and consistency in welding quality and reducing the product defect rate.

[0038] In some embodiments, refer to Figure 1 and Figure 2 The normal to the second connection point 47 divides the solder structure 4 into a first part 44 and a second part 45. That is, the normal to the intersection of the second side 42 and the third side 43 divides the solder structure 4 into a first part 44 and a second part 45. The first part 44 extends away from the outer shell 1, and the second part 45 extends towards the outer shell 1. The molten volume of the first part 44 is less than or equal to the molten volume of the second part 45. In this embodiment, the normal to the intersection of the second side 42 and the third side 43 is perpendicular to the outer wall 112 of the side plate 11.

[0039] In one specific implementation, refer to Figure 1 and Figure 2 The battery casing 100 may also include a boss 5, the outer diameter of which is less than or equal to the inner diameter of the casing 1. The boss 5 is disposed on the bottom surface 22 of the cover plate 2 and extends toward the receiving cavity 12. The boss 5 not only improves the overall structural strength of the cover plate 2 and reduces the risk of deformation of the cover plate 2, but also has a guiding function, which can guide the cover plate 2 to fall quickly into the preset position during the assembly process, thereby improving assembly efficiency.

[0040] The cover plate 2 and the boss 5 can be separate structures or integrally formed. In this embodiment, the cover plate 2 and the boss 5 are integrally formed. This not only achieves a seamless connection between the cover plate 2 and the boss 5, but also significantly shortens the production process and reduces the complexity of the process. At the same time, the integrally formed structure allows for precise control of the dimensions of the cover plate 2 and the boss 5 through the mold, resulting in high consistency between the cover plate 2 and the boss 5. This reduces quality fluctuations caused by assembly errors and lowers the scrap rate.

[0041] As a preferred method, refer to Figure 1 and Figure 2The battery housing 100 may also include a seal 6, which is disposed between the boss 5 and the inner wall 111 of the side plate 11. The seal 6 may be, for example, an O-ring or an elastic gasket. The seal 6 can fill the assembly gap between the boss 5 and the side plate 11, forming an elastic sealing layer, blocking the electrolyte leakage path, thereby improving the sealing effect between the side plate 11 and the boss 5. The seal 6 can also fix the relative position between the side plate 11 and the cover plate 2, ensuring accurate alignment during laser welding. The seal 6 can also prevent welding spatter or oxide residue from entering the interior of the battery housing 100. At the same time, the battery cells are subjected to high-frequency vibrations during vehicle operation, and the elasticity of the seal 6 can absorb some of the energy, preventing fatigue cracking of the weld joint.

[0042] The following provides a method for inspecting the solder mark structure 4 of a battery cell. However, those skilled in the art will understand that the following method for inspecting the solder mark structure 4 of a battery cell is only for illustrating this application and should not be regarded as limiting the scope of protection of this application.

[0043] As an example, the method for inspecting the solder mark structure 4 of a battery cell includes: Completely discharge a single battery cell: Connect the battery cell to be tested to a dedicated discharge device (such as a resistive load discharger) and discharge it until the voltage is ≤0V. After discharge, let it stand for 1-2 hours and confirm that there is no voltage rebound.

[0044] Positioning and fixing: Use a marker to mark the welding position on the outer shell 1 of the battery cell (usually the weld structure 4 between the cover plate 2 and the outer shell 1), fix the battery cell in a special fixture, and ensure that the marked weld structure 4 is perpendicular to the subsequent cutting direction to avoid cutting deviation that would result in an incomplete cross-section of the weld structure 4.

[0045] Cutting: Use a cutting saw to cut off the battery cell to expose the cross-section at the welding position between the cover plate 2 and the outer casing 1.

[0046] Inspection: The cut cross-section is placed under an optical microscope for inspection. Inspection items include, but are not limited to: the cross-sectional shape of the solder structure 4, the key dimensions of the solder structure 4, and the defect judgment of the solder structure 4. Among them, the key dimensions of the solder structure 4 need to be measured online using measurement software. For example, the software measures the weld penetration (e.g., the vertical distance from the second connection point 47 to the first side 41), the weld width (e.g., the vertical distance between the first connection point 46 and the third connection point 48), the width of the heat-affected zone 7 (the area of ​​metal microstructure change around the solder structure 4), and the angle α formed between the line connecting the first connection point 46 and the second connection point 47 and the outer wall 112 of the side plate 11.

[0047] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0048] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0049] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0050] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A battery casing, characterized in that, include: The outer shell (1) includes a side plate (11) which surrounds and forms a receiving cavity (12). The side plate (11) has opposing inner walls (111) and outer walls (112) and a top wall (113) connecting the inner walls (111) and the outer walls (112). Cover plate (2), the cover plate (2) having opposing top surface (21) and bottom surface (22) and a side surface (23) connecting the top surface (21) and the bottom surface (22), the bottom surface (22) of the cover plate (2) being disposed toward the top wall (113) of the side plate (11); A solder joint structure (4) is formed by melting a portion of the side plate (11) and a portion of the cover plate (2) to connect the side plate (11) and the cover plate (2). The solder joint structure (4) has a first connection point (46) located on the outer wall (112) and a second connection point (47) located at the deepest point inside the outer shell (1) or the cover plate (2). The line connecting the first connection point (46) and the second connection point (47) forms an angle α with the outer wall (112) of the side plate (11), satisfying: α>90°.

2. The battery casing according to claim 1, characterized in that, The angle α between the line connecting the first connection point (46) and the second connection point (47) and the outer wall (112) of the side plate (11) satisfies: 120°≤α≤160°.

3. The battery casing according to claim 1, characterized in that, The second connection point (47) is located on the cover plate (2); The maximum depth of the solder mark structure (4) is greater than or equal to the thickness of the side plate (11).

4. The battery casing according to claim 1, characterized in that, The second connection point (47) is located on the side plate (11); The maximum depth of the solder mark structure (4) is less than the thickness of the side plate (11).

5. The battery casing according to claim 4, characterized in that, The maximum depth of the solder mark structure (4) is 0.5-0.9 times the thickness of the side plate (11).

6. The battery casing according to claim 1, characterized in that, The soldering structure (4) also has a third connection point (48) located on the side (23) of the cover plate (2) or on the top surface (21) of the cover plate (2).

7. The battery casing according to claim 1, characterized in that, The normal of the second connection point (47) divides the solder structure (4) into a first part (44) and a second part (45), the first part (44) extending away from the outer shell (1) and the second part (45) extending toward the outer shell (1); Wherein, the melt volume of the first part (44) is less than or equal to the melt volume of the second part (45).

8. The battery casing according to claim 1, characterized in that, The battery housing (100) also includes a boss (5), which is disposed on the bottom surface (22) of the cover plate (2) and extends toward the receiving cavity (12).

9. The battery casing according to claim 8, characterized in that, The battery housing (100) also includes a seal (6), which is disposed between the boss (5) and the inner wall (111) of the side plate (11).

10. A single battery cell, characterized in that, It includes an inner core (200) and a battery housing (100) as described in any one of claims 1-9, wherein the inner core (200) is installed in a receiving cavity (12) of the battery housing (100).

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