Battery housing, battery, and battery module

Abstract

The present application relates to the technical field of batteries, and discloses a battery housing, a battery, and a battery module. The battery housing comprises a housing body; the housing body comprises two opposite abutment surfaces; the two abutment surfaces are welded to form a welding seam structure, so that the housing body can form a hollow housing structure having openings; each abutment surface comprises a bright zone; the width size of the bright zones in a first direction is W, and the wall thickness size of the housing body is T, and it is satisfied that 0.3≤W / T≤0.8. The width size W of the bright zones in the first direction and the wall thickness size T of the housing body are limited to satisfy 0.3≤W / T≤0.8, thereby ensuring that the bright zones of the abutment surfaces occupy sufficient areas. Consequently, during welding, the flat and smooth abutment surfaces can effectively improve the welding quality of the two abutment surfaces, thereby increasing the structural strength and pressure-bearing capacity of the welding seam structure of the battery housing, preventing leakage at the welding seam structure of the battery housing under internal pressure, and improving sealing performance.

Description

Battery casing, battery and battery module

[0001] Cross-reference of related applications

[0002] This application claims priority to Chinese Patent Application No. CN202411919490.5, filed on December 25, 2024, entitled "Battery Casing, Battery and Battery Module", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and in particular to a battery casing, a battery, and a battery module. Background Technology

[0004] The battery casing has the functions of insulation, sealing, current conduction, pressure relief and fuse protection. The current conduction is achieved by welding the terminals on the battery casing to the tabs of the cell terminals, thereby realizing the current conduction function. The insulation function is achieved by wrapping the terminals with plastic parts to prevent contact between the terminals and the casing.

[0005] The battery casing is usually made from raw material sheets through bending, rolling, welding, and cutting processes. When the battery is used for a long time in a cycle of charging and discharging, high temperature and high pressure gas will be generated inside. At this time, the welded joint of the battery casing will be subjected to the pressure brought by the high temperature and high pressure gas. The surface of the raw material sheets used to form the battery casing is relatively rough at the joint, which results in low structural strength and poor pressure resistance of the welded joint of the battery casing after welding. It is easy to leak under the pressure of high temperature and high pressure gas, and the sealing performance is poor.

[0006] Application content

[0007] In view of this, the purpose of this application is to provide a battery casing, battery and battery module with high structural strength, strong pressure resistance, and good sealing performance, which is not prone to leakage under the pressure of high temperature and high pressure gas.

[0008] In a first aspect, this application provides a battery casing, the battery casing including a casing body, the casing body including two opposing mating surfaces, the two opposing mating surfaces being welded to form a weld structure, so that the casing body forms a hollow shell structure with an opening;

[0009] The mating surface includes a bright band with a width of W along the first direction and a wall thickness of T for the outer shell body, satisfying 0.3≤W / T≤0.8.

[0010] Beneficial effects: The battery casing includes a casing body composed of two mating surfaces joined together. By limiting the width W of the bright band on the mating surface along the first direction and the wall thickness T of the casing body, the width W of the bright band along the first direction and the wall thickness T of the casing body satisfy 0.3≤W / T≤0.8. This ensures that the bright band on the mating surface occupies a sufficient area. Therefore, when the two mating surfaces are welded, the smooth and flat mating surfaces can effectively improve the quality of the welding, thereby improving the structural strength and pressure resistance of the battery casing weld structure, preventing leakage of the battery casing weld structure under the pressure of high temperature and high pressure gas, and improving the sealing performance.

[0011] Optionally, the weld structure includes a first boss that protrudes toward the outer shell body along the first direction, and the length of the first boss along the second direction is L1, satisfying 1.4T≤L1≤2T.

[0012] Optionally, the weld structure includes a second boss that protrudes toward the other side of the outer shell body along the first direction, and the length of the second boss along the second direction is L2, satisfying T≤L2≤1.8T.

[0013] Optionally, the length L2 of the second boss is smaller than the length L1 of the first boss.

[0014] Optionally, the height of the first boss protruding along the first direction is h1, and the height of the second boss protruding along the first direction is h2, and 1≤h1 / h2≤4.

[0015] Optionally, the first boss has a protective rounded corner on the side facing away from the second boss;

[0016] And / or, the second boss has the protective rounded corner on the side opposite to the first boss.

[0017] Optionally, the two mating surfaces are joined together using high-frequency welding.

[0018] Optionally, the burst pressure of the outer shell body is P, where P ≥ 1.2 MPa, and the wall thickness T of the outer shell body satisfies 0.3 mm ≤ T ≤ 2 mm.

[0019] Secondly, this application also provides a battery, the battery including a battery casing as described in any of the preceding claims, the battery further including an electrode assembly and a battery cover, the battery cover being disposed over the opening of the battery casing to form a closed receiving cavity, the electrode assembly being housed within the receiving cavity.

[0020] Beneficial effects: By using the aforementioned battery casing, the battery has a high pressure resistance, preventing leakage and scrapping caused by high temperature and high pressure gas exerting pressure on the weld structure after a short period of use, thereby extending the battery's service life and product quality.

[0021] Thirdly, this application also provides a battery module comprising at least two batteries as described above.

[0022] Beneficial effects: By using the aforementioned battery, this battery module avoids the leakage of high-temperature and high-pressure gas at the welded structure of the battery casing during thermal runaway, which would otherwise affect the normal operation of other batteries and thus improve the overall protection and safety of the battery module. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 is a three-dimensional cross-sectional view of the mating surface on the battery casing provided in this application;

[0025] Figure 2 is a cross-sectional plan view of the mating surface on the battery casing provided in this application;

[0026] Figure 3 is a schematic diagram of the structure of the outer casing body of the battery casing provided in this application;

[0027] Figure 4 is a partial cross-sectional view of the weld structure on the battery casing provided in this application;

[0028] Figure 5 is a metallographic image of the battery casing provided in this application, where the fracture point is not at the weld structure during a tensile test.

[0029] Figure 6 is a metallographic image of the battery casing provided in this application, showing the fracture location at the weld structure during a tensile test.

[0030] In the figure: 1. Outer shell body; 11. Butt joint surface; 111. Bright band; 112. Rounded corner band; 113. Shear band; 114. Pressing band; 12. Weld structure; 121. First boss; 122. Second boss; 123. Protective rounded corner. Detailed Implementation

[0031] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0032] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0033] The battery casing has the functions of insulation, sealing, current conduction, pressure relief and fuse protection. The current conduction is achieved by welding the terminals on the battery casing to the tabs of the cell terminals, thereby realizing the current conduction function. The insulation function is achieved by wrapping the terminals with plastic parts to prevent contact between the terminals and the casing.

[0034] The battery casing is usually made from raw material sheets through bending, rolling, welding, and cutting processes. When the battery is used for a long time in a cycle of charging and discharging, high temperature and high pressure gas will be generated inside. At this time, the welded joint of the battery casing will be subjected to the pressure brought by the high temperature and high pressure gas. The surface of the raw material sheets used to form the battery casing is relatively rough at the joint, which results in low structural strength and poor pressure resistance of the welded joint of the battery casing after welding. It is easy to leak under the pressure of high temperature and high pressure gas, and the sealing performance is poor.

[0035] Therefore, in order to improve the structural strength of the weld, enhance the pressure-bearing capacity of the weld, prevent leakage under the pressure of high temperature and high pressure gas, and improve the sealing performance of the weld, this embodiment provides a battery casing.

[0036] As shown in Figures 1 to 6, the battery casing includes a casing body 1, which includes two opposing mating surfaces 11. The two opposing mating surfaces 11 are welded together to form a weld structure 12, so that the casing body 1 forms a hollow shell structure with an opening. The mating surface 11 includes a bright band 111, the width of the bright band 111 along the first direction is W, and the wall thickness of the casing body 1 is T, which satisfies that 0.3≤W / T≤0.8.

[0037] The battery casing includes a casing body 1 formed by splicing two mating surfaces 11. By limiting the width W of the bright band 111 of the mating surfaces 11 along the first direction and the wall thickness T of the casing body 1, the width W of the bright band 111 along the first direction and the wall thickness T of the casing body 1 are made to satisfy 0.3≤W / T≤0.8. This ensures that the bright band 111 of the mating surfaces 11 occupies a sufficient area. Therefore, when the two mating surfaces 11 are welded, the smooth mating surfaces 11 can effectively improve the quality of the welding, thereby improving the structural strength and pressure-bearing capacity of the battery casing weld structure 12, preventing leakage of the battery casing weld structure 12 under the pressure of high temperature and high pressure gas, and improving the sealing performance.

[0038] The structure of the battery casing and the range of the width W of the bright strip 111 along the first direction and the wall thickness T of the casing body 1 are defined, which can be used in various types of power batteries. However, in this embodiment, the battery casing is mainly for blade lithium-ion power batteries, whose positive and negative tabs are located on both sides of the electrode group. Therefore, the casing body 1 is a hollow shell structure with open sides.

[0039] In this embodiment, when the cutting blade cuts the sheet material used to make the outer shell body 1, the cross-section formed after the sheet material is cut can be divided into four regions. When the cutting blade cuts the sheet material, a rounded corner band 112 is formed at the upper end of the cross-section of the sheet material. When the cutting blade continues to press down, the sheet material is cut open by shear force, forming a bright band 111. When the cutting blade continues to move downward, the internal stress of the sheet material reaches the shear limit and begins to fracture, forming a shearing band 113. When the cutting blade continues to move downward, a kneading band 114 is formed at the lower end of the cross-section of the sheet material.

[0040] In this embodiment, for ease of description, the trajectory of the cutting blade punching the sheet material used to make the outer shell body 1 to form the mating surface 11 is defined as the first direction, and X represents the first direction.

[0041] As shown in Table 1, this embodiment provides fifteen sets of embodiments. Under the condition that the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 satisfy the range limitation of 0.3 ≤ W / T ≤ 0.8, tensile tests and helium leak tests are performed on the two mating surfaces 11 after welding to simulate the working environment under high temperature and high pressure gas pressure, in order to determine whether the tensile strength and airtightness of the two mating surfaces 11 after welding meet the requirements. Where the tensile strength is greater than 150 MPa, as shown in Figure 5, and the breakage location is not at the weld structure 12, then the strength requirement is met; where the breakage location is at the weld structure 12, as shown in Figure 6, then the strength requirement is not met. The actual helium leak rate is less than 1 × 10⁻⁶. -7 Pa·m 3 If the value is / s, then the sealing requirement is met.

[0042] Table 1

[0043] In Example 01, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.3. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 168 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 3.2 × 10⁻⁶. -8 Pa·m 3 / s.

[0044] In Example 02, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.45. Tensile and helium detection tests were performed on the two mating surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two mating surfaces 11 was measured to be 172 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 5.7 × 10⁻⁶. -8 Pa·m 3 / s.

[0045] In Example 03, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.55. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 174 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 2.5 × 10⁻⁶. -8 Pa·m 3 / s.

[0046] In Example 04, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.7. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 186 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 3.6 × 10⁻⁶. -8 Pa·m 3 / s.

[0047] In Example 05, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.8. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 198 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 2.2 × 10⁻⁶. -8 Pa·m 3 / s.

[0048] In Example 06, the wall thickness T of the outer shell body 1 was set to 1.2 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.3. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 170 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 6.2 × 10⁻⁶. -9 Pa·m 3 / s.

[0049] In Example 07, the wall thickness T of the outer shell body 1 was set to 1.2 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.6. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 180 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leak rate was 7.9 × 10⁻⁶. -8 Pa·m 3 / s.

[0050] In Example 08, the wall thickness T of the outer shell body 1 was set to 1.2 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.8. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 175 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 9.2 × 10⁻⁶. -9 Pa·m 3 / s.

[0051] In Example 09, the wall thickness T of the outer shell body 1 was set to 2.5 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.35. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 169 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 9.2 × 10⁻⁶. -8 Pa·m 3 / s.

[0052] In Example 10, the wall thickness T of the outer shell body 1 was set to 2.5 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.55. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 173 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 2.0 × 10⁻⁶. -8 Pa·m 3 / s.

[0053] In Example 11, the wall thickness T of the outer shell body 1 was set to 2.5 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.75. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 193 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 2.9 × 10⁻⁶. -8 Pa·m 3 / s.

[0054] In Example 12, the wall thickness T of the outer shell body 1 was set to 3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.3. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 171 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 3.2 × 10⁻⁶. -8 Pa·m 3 / s.

[0055] In Example 13, the wall thickness T of the outer shell body 1 was set to 3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.45. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 175 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 6.2 × 10⁻⁶. -8 Pa·m 3 / s.

[0056] In Example 14, the wall thickness T of the outer shell body 1 was set to 3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.6. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 182 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 7.2 × 10⁻⁶. -8 Pa·m 3 / s.

[0057] In Example 15, the wall thickness T of the outer shell body 1 was set to 3 mm, and the ratio between the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.8. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 196 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 7.2 × 10⁻⁶. -9 Pa·m 3 / s.

[0058] As can be seen from Examples 01 to 15, when the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 satisfy the condition of 0.3≤W / T≤0.8, tensile tests and helium leak tests are performed on the two butt joint surfaces 11 after welding. The tensile strength of both butt joint surfaces 11 after welding is greater than 150 MPa, and the fracture location is not at the weld structure 12. In addition, the airtightness of the two butt joint surfaces 11 after welding meets the requirements, and the actual leakage rate measured by helium leak testing is less than 1×10⁻⁶. -7 Pa·m 3 If the value is / s, then the sealing requirement is met.

[0059] As shown in Table 2, this embodiment provides nineteen comparative examples. Under the condition that the width W of the bright strip 111 along the first direction and the wall thickness T of the outer shell body 1 do not meet the range limitation of 0.3 ≤ W / T ≤ 0.8, tensile tests and helium leak tests are performed on the two butt joint surfaces 11 after welding to simulate the working environment under high temperature and high pressure gas pressure. This is to determine whether the tensile strength and airtightness of the two butt joint surfaces 11 after welding meet the requirements. If the tensile strength is greater than 150 MPa and the fracture location is not at the weld structure 12, then the strength requirement is met. The actual helium leak rate is less than 1 × 10⁻⁶. -7 Pa·m 3 If the value is / s, then the sealing requirement is met.

[0060] Table 2

[0061] In Comparative Example 01, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.28. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding was measured to be 148 MPa, and the fracture location was at the weld structure 12. The actual helium detection leakage rate was 3.2 × 10⁻⁶. -8 Pa·m 3 / s.

[0062] In Comparative Example 02, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.25. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding was measured to be 142 MPa, and the fracture location was at the weld structure 12. The actual helium leak rate was 6.0 × 10⁻⁶. -8 Pa·m 3 / s.

[0063] In Comparative Example 03, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.15. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 138 MPa, and the fracture location was at the weld structure 12. The actual helium detection leakage rate was 7.6 × 10⁻⁶. -9 Pa·m 3 / s.

[0064] In Comparative Example 04, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.1. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding was measured to be 131 MPa, and the fracture location was at the weld structure 12. The actual helium leak rate was 9.1 × 10⁻⁶. -8 Pa·m 3 / s.

[0065] In Comparative Example 05, the wall thickness T of the outer shell body 1 was set to 1.2 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.25. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 144 MPa, and the fracture location was at the weld structure 12. The actual helium detection leakage rate was 1.9 × 10⁻⁶. -8 Pa·m 3 / s.

[0066] In Comparative Example 06, the wall thickness T of the outer shell body 1 was set to 1.2 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.15. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding was measured to be 135 MPa, and the fracture location was at the weld structure 12. The actual helium leak rate was 3.5 × 10⁻⁶. -8 Pa·m 3 / s.

[0067] In Comparative Example 07, the wall thickness T of the outer shell body 1 was set to 2.5 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.25. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding was measured to be 146 MPa, and the fracture location was at weld structure 12. The actual helium detection leakage rate was 7.1 × 10⁻⁶. -8 Pa·m 3 / s.

[0068] In Comparative Example 08, the wall thickness T of the outer shell body 1 was set to 2.5 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.2. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding was measured to be 140 MPa, and the fracture location was at the weld structure 12. The actual helium detection leakage rate was 5.5 × 10⁻⁶. -8 Pa·m 3 / s.

[0069] In Comparative Example 09, the wall thickness T of the outer shell body 1 was set to 3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.28. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding was measured to be 149 MPa, and the fracture location was at the weld structure 12. The actual helium detection leakage rate was 3.1 × 10⁻⁶. -8 Pa·m 3 / s.

[0070] In Comparative Example 10, the wall thickness T of the outer shell body 1 was set to 3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.2. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 141 MPa, and the fracture location was at the weld structure 12. The actual helium detection leakage rate was 7.3 × 10⁻⁶. -8 Pa·m 3 / s.

[0071] As shown in Comparative Examples 01 to 10, when the ratio of the width W of the bright band 111 along the first direction to the wall thickness T of the outer shell body 1 is less than the minimum value of the range 0.3 ≤ W / T ≤ 0.8, tensile tests and helium leak tests are performed on the two butt joint surfaces 11 after welding. The tensile strength of both butt joint surfaces 11 after welding is less than 150 MPa, and the fracture location is at the weld structure 12. However, the airtightness of the two butt joint surfaces 11 after welding meets the requirements, and the actual leakage rate measured by helium leak testing is less than 1 × 10⁻⁶. -7 Pa·m 3 / s, meeting sealing requirements.

[0072] In Comparative Example 11, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.85. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 166 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 2.2 × 10⁻⁶. -5 Pa·m 3 / s.

[0073] In Comparative Example 12, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.95. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 178 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 7.0 × 10⁻⁶. -6 Pa·m 3 / s.

[0074] In Comparative Example 13, the wall thickness T of the outer shell body 1 was set to 0.3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 1. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 186 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 7.2 × 10⁻⁶. -7 Pa·m 3 / s.

[0075] In Comparative Example 14, the wall thickness T of the outer shell body 1 was set to 1.2 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.9. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 170 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 3.1 × 10⁻⁶. -7 Pa·m 3 / s.

[0076] In Comparative Example 15, the wall thickness T of the outer shell body 1 was set to 1.2 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.95. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 180 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 4.9 × 10⁻⁶. -5 Pa·m 3 / s.

[0077] In Comparative Example 16, the wall thickness T of the outer shell body 1 was set to 2.5 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.85. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 166 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 7.2 × 10⁻⁶. -6 Pa·m 3 / s.

[0078] In Comparative Example 17, the wall thickness T of the outer shell body 1 was set to 2.5 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 1. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 190 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 9.0 × 10⁻⁶. -7 Pa·m 3 / s.

[0079] In Comparative Example 18, the wall thickness T of the outer shell body 1 was set to 3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 0.85. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 168 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 1.6 × 10⁻⁶. -5 Pa·m 3 / s.

[0080] In Comparative Example 19, the wall thickness T of the outer shell body 1 was set to 3 mm, and the ratio between the width W of the bright band 111 along the first direction and the wall thickness T of the outer shell body 1 was set to W / T = 1. Tensile and helium detection tests were performed on the two butt joint surfaces 11 after welding. The strength of the outer shell body 1 at fracture after welding the two butt joint surfaces 11 was measured to be 192 MPa, and the fracture location was not at the weld structure 12. The actual helium detection leakage rate was 3.6 × 10⁻⁶. -6 Pa·m 3 / s.

[0081] As shown in Comparative Examples 11 to 19, when the ratio of the width W of the bright band 111 along the first direction to the wall thickness T of the outer shell body 1 is greater than the maximum value of the range 0.3 ≤ W / T ≤ 0.8, tensile tests and helium detection tests are performed on the two butt joint surfaces 11 after welding. The tensile strength of both butt joint surfaces 11 after welding is greater than 150 MPa, and the fracture location is not at the weld structure 12. However, the measured leakage rate of the helium detection after welding both butt joint surfaces 11 is greater than 1 × 10⁻⁶. -7 Pa·m 3 / s, which does not meet the airtightness requirements.

[0082] Optionally, as shown in Figure 4, the weld structure 12 includes a first boss 121, which protrudes towards the outer shell body 1 along a first direction. The length of the first boss 121 along a second direction is L1, satisfying 1.4T≤L1≤2T. Since the first boss 121 is located inside the outer shell body 1, limiting the length L1 of the first boss 121 along the second direction to satisfy 1.4T≤L1≤2T avoids both situations where the length L1 is too small, affecting the structural strength after welding, and where the length L1 is too large, occupying too much space and resulting in low energy density. In this embodiment, after welding is completed, the first boss 121 is ground to ensure that the length L1 of the first boss 121 along the second direction meets the requirements.

[0083] Optionally, as shown in Figure 4, the weld structure 12 includes a second boss 122, which protrudes towards the other side of the outer casing 1 along a first direction. The length of the second boss 122 along a second direction is L2, and satisfies T≤L2≤1.8T. Since the second boss 122 is located outside the outer casing 1, limiting the length L2 of the second boss 122 along the second direction to satisfy T≤L2≤1.8T avoids both situations where the length L2 is too small, affecting the structural strength after welding, and where the length L2 is too large, affecting the flatness of the battery casing. In this embodiment, after welding, the second boss 122 is ground to ensure that the length L2 of the second boss 122 along the second direction meets the requirements.

[0084] In this embodiment, the two mating surfaces 11 are joined by high-frequency welding. By using high-frequency welding, the skin effect and proximity effect are utilized to quickly concentrate electrical energy on the surface of the weldment, so that the metal is heated to the melting point quickly, thus accelerating the heating speed, shortening the time required for the welding process and improving production efficiency.

[0085] The high-frequency welding process utilizes high-frequency current to generate resistance heat on the metal surface, heating the mating surfaces 11 to a molten state. Simultaneously, extrusion pressure is applied to fuse the two mating surfaces 11 together for welding. During the mutual extrusion, a first protrusion 121 and a second protrusion 122 with opposite directions of elevation are formed. In this embodiment, for ease of description, the direction of the elevation of the first protrusion 121 and the second protrusion 122 is defined as the second direction, and Y is used to represent the second direction.

[0086] Optionally, the length L2 of the second boss 122 is smaller than the length L1 of the first boss 121. Since the second boss 122 is located on the outside of the outer shell body 1 and the first boss 121 is located on the inside of the outer shell body 1, and the flatness requirement of the outer shell body 1 needs to be ensured, the limitation of the second boss 122 is stricter than that of the first boss 121 located inside, that is, the length L2 of the second boss 122 is smaller than the length L1 of the first boss 121.

[0087] Optionally, as shown in Figure 4, the height dimension of the first boss 121 protruding along the first direction is h1, and the height dimension of the second boss 122 protruding along the first direction is h2, satisfying 1≤h1 / h2≤4. By limiting the height dimension h1 of the first boss 121 and the height dimension h2 of the second boss 122 protruding along the first direction, both satisfy 1≤h1 / h2≤4, on the one hand, it avoids the protrusion height being too small, which would affect the strength and airtightness after welding; on the other hand, it avoids the first boss 121 protruding too much inward, occupying space, and avoids the second boss 122 protruding too much outward, which would affect the flatness of the outer shell body 1.

[0088] Optionally, as shown in Figure 4, the first boss 121 has a protective rounded corner 123 on the side facing away from the second boss 122. By providing a protective rounded corner 123 on the side of the first boss 121 facing away from the second boss 122, the first boss 121 is prevented from scratching the internal electrode assembly.

[0089] Optionally, as shown in Figure 4, the second protrusion 122 has a protective rounded corner 123 on the side facing away from the first protrusion 121. By providing a protective rounded corner 123 on the side of the second protrusion 122 facing away from the first protrusion 121, it is possible to prevent scratching adjacent batteries when multiple batteries are combined.

[0090] Optionally, the burst pressure of the outer casing 1 is P, where P ≥ 1.2 MPa, and the wall thickness T of the outer casing 1 satisfies 0.3 mm ≤ T ≤ 2 mm. By limiting the wall thickness T of the outer casing 1 to meet the requirement of 0.3 mm ≤ T ≤ 2 mm, the burst pressure P ≥ 1.2 MPa of the outer casing 1 is thus satisfied.

[0091] In this embodiment, a battery is also provided, comprising the aforementioned battery casing, electrode assembly, and battery cover. The battery cover covers the opening of the battery casing to form a closed receiving cavity, within which the electrode assembly is housed. By employing the aforementioned battery casing, the battery possesses high pressure resistance, preventing leakage and failure due to high-temperature, high-pressure gas exerting pressure on the weld structure 12 after a short period of use, thereby extending the battery's lifespan and improving product quality.

[0092] In this embodiment, a battery module is also provided, comprising at least two of the aforementioned batteries. By using the aforementioned batteries, this battery module prevents high-temperature, high-pressure gases from leaking at the weld structure 12 of the battery casing during thermal runaway, thus avoiding leakage and affecting other normally operating batteries. This improves the overall protection and safety of the battery module.

[0093] Obviously, the above embodiments of this application are merely examples for clear illustration and are not intended to limit the implementation of this application. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the scope of protection of this application. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of the claims of this application. Industrial applicability

[0094] The battery casing of this application includes a casing body composed of two mating surfaces joined together. By limiting the width W of the bright band on the mating surface along the first direction and the wall thickness T of the casing body, the width W of the bright band along the first direction and the wall thickness T of the casing body satisfy 0.3≤W / T≤0.8. This ensures that the bright band on the mating surface occupies a sufficient area. Therefore, when the two mating surfaces are welded, the smooth mating surface can effectively improve the quality of the welding, thereby improving the structural strength and pressure resistance of the battery casing weld structure, preventing leakage of the battery casing weld structure under the pressure of high temperature and high pressure gas, and improving the sealing performance.

Claims

1. A battery housing, characterized by The battery casing includes a casing body, which includes two opposing mating surfaces. The two opposing mating surfaces are welded together to form a weld structure, so that the casing body forms a hollow shell structure with an opening. The mating surface includes a bright band with a width of W along the first direction and a wall thickness of T for the outer shell body, satisfying 0.3≤W / T≤0.

8.

2. The battery case of claim 1, wherein, The weld structure includes a first boss, which protrudes towards the outer shell body along the first direction. The length of the first boss along the second direction is L1, and satisfies 1.4T≤L1≤2T.

3. The battery case of claim 2, wherein, The weld structure includes a second boss, which protrudes towards the other side of the outer shell body along the first direction. The length of the second boss along the second direction is L2, and it satisfies T≤L2≤1.8T.

4. The battery case of claim 3, wherein, The length L2 of the second boss is smaller than the length L1 of the first boss.

5. The battery case of claim 3, wherein, The height of the first boss protruding along the first direction is h1, and the height of the second boss protruding along the first direction is h2, and 1≤h1 / h2≤4.

6. The battery case of claim 5, wherein, The first boss has a protective rounded corner on the side facing away from the second boss; And / or, the second boss has the protective rounded corner on the side opposite to the first boss.

7. The battery case of claim 1, wherein, The two mating surfaces are joined together using high-frequency welding.

8. The battery case of claim 1, wherein, The burst pressure of the outer shell body is P, P≥1.2MPa, and the wall thickness T of the outer shell body satisfies 0.3mm≤T≤2mm.

9. A battery characterized by The battery includes a battery casing as described in any one of claims 1-8, and the battery further includes an electrode assembly and a battery cover plate, the battery cover plate being disposed over the opening of the battery casing to form a closed receiving cavity, the electrode assembly being housed within the receiving cavity.

10. A battery module, characterized by The battery module includes at least two batteries as described in claim 9.

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