Battery cell shell, battery cell and battery pack

Abstract

The present invention relates to the field of battery technology and discloses a cell housing, a cell, and a battery pack. The cell housing includes four sidewalls, with adjacent sidewalls connected by transition sections. The transition sections are arc-shaped, with an outer fillet radius R, an inner fillet radius r, and a minimum sidewall thickness b, such that R-r ≤ b. The present invention controls the relationship between the outer fillet radius R of the transition section, the inner fillet radius r of the transition section, and the minimum sidewall thickness b within the range of R-r ≤ b. By specifying parameters such as the thickness of the cell housing sidewalls and the transition section at weak points, the present invention ensures that the cell housing is fatigue-resistant and that the cell has sufficient safety.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cell casing, a battery cell and a battery pack. Background Art

[0002] With the continuous development of technology, users' requirements for new energy batteries are becoming increasingly higher. To improve the safety performance of battery cells, pressure relief mechanisms are often installed on battery cells. When a battery cell is operating abnormally and gas is generated inside, the pressure relief mechanism can be used to discharge the gas, thus preventing major safety accidents.

[0003] In order to maximize the capacity of the battery cells and make the pack safer, it is very effective to make the battery cell shell thinner and adjust the pressure relief structure from the cover to the side wall of the shell.

[0004] However, for the shell itself, if the shell is made thin, the joints where the four walls of the shell are connected will also be too weak. When the battery cell produces gas, the shell will experience breathing fatigue, especially the joints, that is, the rounded corners are the weakest points of breathing fatigue and there is a risk of cracking. Therefore, the structural design and parameter regulations for the rounded corners are crucial. Summary of the Invention

[0005] In view of this, the present invention provides a battery cell shell, a battery cell and a battery pack to solve the problem that the joints where the four walls of the battery cell shell are connected are weak and there is a risk of cracking.

[0006] In a first aspect, the present invention provides a battery cell shell, comprising four side walls, adjacent side walls being connected by a transition section, the transition section being an arc, the outer fillet radius of the transition section being R, the inner fillet radius of the transition section being r, and the minimum thickness of the side wall being b, then, Rr≤b.

[0007] Beneficial effect: The relationship among the outer fillet radius R of the transition section, the inner fillet radius r of the transition section and the minimum thickness b of the side wall is controlled within the range of Rr≤b. By specifying the thickness of the side wall of the battery cell shell and the parameters of the weak point transition section and other positions, it is ensured that the battery cell shell is fatigue-resistant and the battery cell has sufficient safety.

[0008] In an optional embodiment, the range of the inner fillet radius r of the transition section is 0.3 mm ≤ r ≤ 1.6 mm, and the range of the outer fillet radius R of the transition section is 0.6 mm ≤ R ≤ 2.5 mm.

[0009] Beneficial Effect: For the transition section, the inner fillet radius r is controlled within the range of 0.3mm to 1.5mm, which can meet the fatigue strength requirements without excessively affecting the capacity of the battery cell. Since Rr ≤ b is required, the outer fillet radius R of the transition section is controlled within the range of 0.6mm to 2.5mm.

[0010] In an optional embodiment, the thickness of the four side walls is b, and the thickness range of the side walls is 0.1 mm ≤ b ≤ 3.0 mm.

[0011] Beneficial effect: The battery cell shell has a constant wall thickness, and the thickness of the side walls connected at both ends of the transition section is b, so the battery cell shell is easy to process; when the battery cell shell has a constant wall thickness, the thickness of the side walls of the battery cell shell is controlled within the range of 0.1 mm to 1.0 mm, which can control the total weight of the battery cell shell.

[0012] In an optional embodiment, the battery cell shell is manufactured by a welding process and meets the following conditions: Rr=b, 0.1mm≤b≤1.0mm, 0.5mm≤r≤1.6mm; or, the battery cell shell is manufactured by an extrusion process and meets the following conditions: Rr≤b, 0.2mm≤b≤1.0mm, 0.4mm≤r≤1.6mm; or, the battery cell shell is manufactured by a stamping process and meets the following conditions: Rr≤b, 0.3mm≤b≤1.0mm, 0.3mm≤r≤1.6mm.

[0013] Beneficial effect: When the battery cell shell has a uniform wall thickness, it can be formed by welding, extrusion or stamping. When the battery cell shell is formed by adopting different processes, the thickness b of the side wall of the battery cell shell, the outer fillet radius R of the transition section and the inner fillet radius r of the transition section are controlled within the corresponding range, which can meet the needs of improving the strength of the transition section of the battery cell shell while adapting to different process characteristics and ensuring the processing quality of the battery cell shell.

[0014] In an optional embodiment, among the four side walls, at least one side wall has a thickness of b, and the thicknesses of the remaining side walls are a. The thickness a of the side walls may be in the range of 0.3 mm ≤ a ≤ 1.5 mm, and 0 ≤ ab < 1.

[0015] Advantageous Effects: Since the thickness of the thicker sidewall is a, controlling the thickness a of the thicker sidewall within the range of 0.3 mm to 1.5 mm can ensure the strength of the battery cell housing while keeping the weight and space occupied by the battery cell housing within a reasonable range. By controlling the thickness difference ab between different sidewalls within the range of 0 to 1, the thickness difference between different sidewalls can be kept within a reasonable range, reducing the difficulty of forming the battery cell housing.

[0016] In an optional embodiment, the battery cell shell is manufactured by an extrusion process and meets the following conditions: Rr≤b, 0.6mm≤R≤2.5mm, 0.3mm≤a≤1.5mm, 0.2mm≤b≤1.0mm, 0.4mm≤r≤1.6mm; or, the battery cell shell is manufactured by a stamping process and meets the following conditions: Rr≤b, 0.6mm≤R≤2.5mm, 0.4mm≤a≤1.5mm, 0.3mm≤b≤1.0mm, 0.3mm≤r≤1.6mm.

[0017] Beneficial effect: When the battery cell shell has unequal wall thickness, it can be formed by processes such as extrusion or stamping. When the battery cell shell is formed by adopting different processes, the thickness b of the side wall of the battery cell shell, the outer fillet radius R of the transition section, and the inner fillet radius r of the transition section are controlled within the corresponding range, which can meet the needs of improving the strength of the transition section of the battery cell shell while adapting to different process characteristics and ensuring the processing quality of the battery cell shell.

[0018] In an optional embodiment, the battery cell shell is made of aluminum, and the thickness b of the side wall of the battery cell shell is in the range of 0.15mm≤b≤1.0mm; or, the battery cell shell is made of steel, and the thickness b of the side wall of the battery cell shell is in the range of 0.1mm≤b≤0.5mm.

[0019] Beneficial effect: In this way, it can adapt to different materials and different manufacturing processes, reducing processing difficulty.

[0020] In an optional embodiment, at least one of the four side walls is provided with an explosion-proof valve, and the thickness of the side wall provided with the explosion-proof valve is a, and 0≤ab<1.

[0021] Beneficial effects: By setting up an explosion-proof valve, when thermal runaway occurs inside the battery, the explosion-proof valve opens to release pressure and exhaust, preventing the battery cell from catching fire or exploding due to excessive internal air pressure; when an explosion-proof valve is set on the side wall of the battery cell shell, the thickness of the side wall where the explosion-proof valve is located is not less than the thickness of other side walls, which can ensure the strength of the side wall where the explosion-proof valve is located and ensure the safety of the battery.

[0022] In a second aspect, the present invention further provides a battery cell comprising a pole group, a cover plate, and a battery cell shell according to any one of the above technical solutions, wherein the pole group is arranged in the battery cell shell; the cover plate is arranged at the end of the battery cell shell to encapsulate the pole group in the battery cell shell.

[0023] Beneficial Effects: Because the battery cell includes the battery cell casing of the above embodiment, the relationship between the outer fillet radius R of the transition section, the inner fillet radius r of the transition section, and the minimum sidewall thickness b of the battery cell casing is controlled within the range of Rr ≤ b. By specifying the thickness of the sidewall of the battery cell casing and the parameters of the weak point transition section, the fatigue resistance of the battery cell casing is improved, thereby ensuring sufficient safety of the battery cell. In addition, because the battery cell includes the battery cell casing of the above embodiment, the battery cell also has all the beneficial effects of the battery cell casing, which will not be repeated here.

[0024] Because the battery cell includes a battery cell shell, it has the same effect as the battery cell shell and is not described in detail here.

[0025] In a third aspect, the present invention further provides a battery pack comprising the battery cell in the above technical solution.

[0026] Beneficial effects: Since the battery pack includes battery cells, it has the same effects as the battery cells and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a schematic structural diagram of a battery cell casing according to an embodiment of the present invention;

[0029] Figure 2 for Figure 1 A side view of the cell housing is shown;

[0030] Figure 3 for Figure 2 A partially enlarged schematic diagram of the transition sections at both ends of the first side wall;

[0031] Figure 4 Schematic diagram of the partial structure of the transition section between the first side wall and the fourth side wall of a battery cell casing of equal wall thickness;

[0032] Figure 5 A schematic diagram of the partial structure of the transition section between the first side wall and the fourth side wall in a battery cell casing with unequal wall thickness;

[0033] Figure 6 This is a schematic structural diagram of another battery cell casing according to an embodiment of the present invention;

[0034] Figure 7 This is a schematic structural diagram of a battery cell according to an embodiment of the present invention;

[0035] Figure 8 for Figure 7 The schematic diagram of the structure of the cracking position of the battery cell when thermal runaway occurs is shown;

[0036] Figure 9 This is a schematic structural diagram of another battery cell according to an embodiment of the present invention;

[0037] Figure 10 for Figure 9 The schematic diagram shows the structure of the cracking location of the battery cell when thermal runaway occurs.

[0038] Description of reference numerals:

[0039] 10. Battery cell housing; 1. Side wall; 11. First side wall; 12. Second side wall; 13. Third side wall; 14. Fourth side wall; 2. Transition section; 3. Explosion-proof valve; 100. Battery cell; 20. Cover plate. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0041] Currently, in the shell breathing fatigue test, due to the thin shell, there is a risk of cracking, and the weakest point is the connection between the four walls, that is, the rounded corners. When the battery cell generates gas, this is the point with the lowest fatigue strength and the location where fatigue occurs most seriously. Secondly, when the battery cell has thermal runaway, if the explosion-proof valve fails, the rounded corners of the shell are the weakest and are also the first and most likely location for the shell to tear. In order to ensure that the battery cell shell can withstand fatigue and ensure the safety of the battery cell, it is particularly important to design and specify parameters such as the shell wall thickness and rounded corners.

[0042] The following combination Figures 1 to 10 , describing embodiments of the present invention.

[0043] According to an embodiment of the present invention, on the one hand, a battery cell shell 10 is provided, including four side walls 1, adjacent side walls 1 are connected by transition sections 2, the transition sections 2 are arcs, the outer fillet radius of the transition sections 2 is R, the inner fillet radius of the transition sections 2 is r, and the minimum thickness of the side walls 1 is b, then, Rr≤b.

[0044] The relationship among the outer fillet radius R of the transition section 2, the inner fillet radius r of the transition section 2, and the minimum thickness b of the side wall 1 is controlled within the range of Rr≤b. By specifying the parameters of the thickness of the side wall 1 of the battery cell housing and the weak point of the transition section 2, it is ensured that the battery cell housing 10 is fatigue-resistant and the battery cell has sufficient safety.

[0045] In one embodiment, the range of the inner fillet radius r of the transition section 2 is 0.3 mm ≤ r ≤ 1.6 mm, and the range of the outer fillet radius R of the transition section 2 is 0.6 mm ≤ R ≤ 2.5 mm.

[0046] For transition section 2, the inner fillet radius r is controlled within the range of 0.5mm to 1.5mm, which can meet fatigue strength requirements without significantly affecting the capacity of the battery cell. Since Rr ≤ b is required, the outer fillet radius R of transition section 2 is controlled within the range of 0.6mm to 2.5mm.

[0047] The cell housing 10 includes four side walls 1 , which are connected in pairs to form four transition sections 2 .

[0048] Due to different manufacturing processes, the thickness of the four side walls 1 of the battery cell housing includes the following three implementations:

[0049] First, the thickness of the four side walls 1 are the same, that is, the cell housing has a uniform wall thickness, and the thickness of each side wall 1 is b.

[0050] Second, the thickness of one of the side walls 1 is a, and the thicknesses of the other three side walls 1 are all b, and a ≥ b. That is, the thickness of one of the side walls 1 is greater than the thicknesses of the other three side walls 1, and the thicknesses of the other three side walls 1 are equal.

[0051] Third, among the four side walls 1, the thickness of the first set of two opposing side walls 1 is a, and the thickness of the second set of two opposing side walls 1 is b, and a ≥ b. That is, the thicknesses of the two opposing side walls 1 are equal, and the thicknesses of the two adjacent side walls 1 are unequal.

[0052] In one embodiment, the thickness of the four side walls 1 is b, and the thickness range of the side walls is 0.1 mm ≤ b ≤ 3.0 mm.

[0053] Such a cell shell has a constant wall thickness, and the thickness of the side walls 1 connected at both ends of the transition section 2 is b, and the cell shell 10 is easy to process; when the cell shell has a constant wall thickness, the thickness of the side walls of the cell shell is controlled within the range of 0.1 mm to 1.0 mm, which can control the total weight of the cell shell.

[0054] In an optional embodiment, the battery cell shell 10 is manufactured by a welding process and meets the following conditions: Rr=b, 0.1mm≤b≤1.0mm, 0.5mm≤r≤1.6mm; or, the battery cell shell 10 is manufactured by an extrusion process and meets the following conditions: Rr≤b, 0.2mm≤b≤1.0mm, 0.4mm≤r≤1.6mm; or, the battery cell shell 10 is manufactured by a stamping process and meets the following conditions: Rr≤b, 0.3mm≤b≤1.0mm, 0.3mm≤r≤1.6mm.

[0055] When the cell shell 10 has a uniform wall thickness, it can be formed by welding, extrusion or stamping. When the cell shell 10 is formed by different processes, the thickness b of the side wall of the cell shell 10, the outer fillet radius R of the transition section 2, and the inner fillet radius r of the transition section 2 are controlled within the corresponding range. This can improve the strength of the transition section 2 of the cell shell 10 while adapting to different process characteristics and ensuring the processing quality of the cell shell 10.

[0056] Specifically, the welding process includes a bending high-frequency welding process or a bending laser welding process.

[0057] Specifically, the extrusion process includes hot extrusion, hot extrusion + cold drawing process or cold extrusion process.

[0058] In one embodiment, among the four side walls 1 , at least one side wall 1 has a thickness of b, and the thicknesses of the remaining side walls 1 are a. The thickness a of the side walls 1 may be in the range of 0.3 mm ≤ a ≤ 1.5 mm, and 0 ≤ ab < 1.

[0059] Specifically, the thickness of one sidewall 1 can be b, and the thickness of the other three sidewalls 1 can be a; the thickness of two sidewalls 1 can also be b, and the thickness of the other two sidewalls 1 can be a. Furthermore, the thickness of two opposite sidewalls 1 in one group can be b, and the thickness of two opposite sidewalls 1 in another group can be a. Since the thickness of the thicker sidewall 1 is a, controlling the thickness a of the thicker sidewall 1 within the range of 0.3mm to 1.5mm can ensure the strength of the battery cell shell while keeping the weight and occupied space of the battery cell shell within a reasonable range. By controlling the value of the thickness difference ab of different sidewalls 1 within the range of 0 to 1, it can be ensured that the thickness difference of different sidewalls 1 is not too large, reducing the difficulty of forming the battery cell shell. It can be understood that when ab=0, a=b, that is, the thickness of the four sidewalls 1 is equal.

[0060] In an optional embodiment, the battery cell shell is manufactured by an extrusion process and meets the following conditions: Rr≤b, 0.6mm≤R≤2.5mm, 0.3mm≤a≤1.5mm, 0.2mm≤b≤1.0mm, 0.4mm≤r≤1.6mm; or, the battery cell shell is manufactured by a stamping process and meets the following conditions: Rr≤b, 0.6mm≤R≤2.5mm, 0.4mm≤a≤1.5mm, 0.3mm≤b≤1.0mm, 0.3mm≤r≤1.6mm.

[0061] When the cell shell 10 has unequal wall thicknesses, it can be formed by processes such as extrusion or stamping. When the cell shell 10 is formed by adopting different processes, the thickness b of the side wall of the cell shell 10, the outer fillet radius R of the transition section 2, and the inner fillet radius r of the transition section 2 are controlled within the corresponding ranges. This can improve the strength of the transition section 2 of the cell shell 10 while adapting to different process characteristics and ensuring the processing quality of the cell shell 10.

[0062] Specifically, the extrusion process includes hot extrusion, hot extrusion + cold drawing process or cold extrusion process.

[0063] In one embodiment, the cell housing is made of aluminum, and the thickness b of the side wall 1 of the cell housing is in the range of 0.15 mm ≤ b ≤ 1.0 mm; or, the cell housing is made of steel, and the thickness b of the side wall 1 of the cell housing is in the range of 0.1 mm ≤ b ≤ 0.5 mm.

[0064] When the cell housing is made of aluminum, the thickness b of the sidewall 1 of the cell housing is controlled within the range of 0.2 mm to 1 mm. When the cell housing is made of steel, the thickness b of the sidewall 1 of the cell housing is controlled within the range of 0.1 mm to 0.5 mm. This allows for adaptability to different materials and manufacturing processes, reducing processing difficulty. Of course, the cell housing is not limited to the aforementioned aluminum or steel; other materials, such as nickel-plated steel, may also be used.

[0065] Specifically, when different types of battery cell casings are manufactured using different processes, the value ranges of various parameters are shown in Table 1.

[0066] Table 1:

[0067]

[0068] The following provides 50 examples and 10 comparative examples of different types of battery cell shells manufactured by different processes, wherein the battery cell shells are aluminum shells, as shown in Table 2.

[0069] Table 2:

[0070]

[0071]

[0072] When the battery cell shell is an aluminum shell, in addition to the embodiments provided in Table 2 above, the following embodiments may also be included:

[0073] For battery cell shells with equal wall thickness, when using welding technology (bending laser welding or bending high-frequency welding), the value of r can also be 1.3mm, 1.5mm or 1.6mm; the value of b can also be 0.1mm, 0.9mm or 1.0mm.

[0074] For battery cell shells with equal or unequal wall thicknesses, using an extrusion process (hot extrusion or hot extrusion + cold drawing or cold extrusion), the value of b can also be 1.0 mm; the value of R can also be 2.0 mm, 2.2 mm or 2.5 mm.

[0075] For battery cell shells with equal wall thickness, an extrusion process (hot extrusion or hot extrusion + cold drawing or cold extrusion) is adopted, and the value of a can also be 0.2 mm, 0.3 mm or 1.0 mm.

[0076] For battery cell shells with different wall thicknesses, an extrusion process (hot extrusion or hot extrusion + cold drawing or cold extrusion) is adopted, and the value of a can also be 1.3 mm or 1.5 mm.

[0077] For cell casings with equal or unequal wall thicknesses, using a stamping process, the value of r can also be 0.3mm or 1.5mm; the value of b can also be 0.3mm, 0.9mm or 1.0mm; and the value of R can also be 0.6mm, 1.0mm, 2.0mm, 2.3mm or 2.5mm.

[0078] For battery cell shells with equal wall thickness, using a stamping process, the value of a can also be 0.3 mm, 0.6 mm, 1.0 mm, 1.2 mm, 1.3 mm or 1.5 mm.

[0079] For battery cell shells with different wall thicknesses, the value of a can also be 0.4 mm or 1.5 mm by using a stamping process.

[0080] The following provides 10 examples and 2 comparative examples of different types of battery cell shells manufactured by different processes, wherein the battery cell shell is a steel shell, as shown in Table 3.

[0081] Table 3:

[0082]

[0083] When the battery cell housing is a steel shell, in addition to the embodiments provided in Table 3 above, the following embodiments may also be included:

[0084] The cell shell has a constant wall thickness. When a welding process (bending laser welding or bending high-frequency welding) is used, the value of r can also be 1.3 mm, 1.5 mm or 1.6 mm; the value of b can also be 0.6 mm, 0.8 mm or 1.0 mm.

[0085] According to the comparison of the examples and comparative examples in Table 2 and Table 3, the analysis results are as follows:

[0086] For Comparative Example 1 in Table 2, when a = 1.5 mm, b = 1.5 mm, R = 2.5 mm, and r = 1 mm, regardless of whether the bending laser welding or bending high-frequency welding manufacturing processes are used, the following problem exists: the wall thickness is out of tolerance, that is, the wall thickness is too thick, resulting in excessive weight of the battery cell housing 10, reducing the battery cell energy density, and making it unsuitable for use as a battery cell housing. Specifically, for the same dimensions, the thicker the wall, the smaller the internal space of the battery cell housing, the smaller the volume that can accommodate the electrode group, and the lower the energy density of the battery cell. Therefore, excessive wall thickness will reduce the energy density of the battery cell.

[0087] For Comparative Example 2 in Table 2, it shows that: when a=0.8mm, b=0.8mm, R=2.2mm, and r=1.1mm, no matter which of the two manufacturing processes, bending laser welding or bending high-frequency welding, is used, the following problems exist: the difference between the outer fillet radius R of the transition section 2 and the inner fillet radius r of the transition section 2 is too large, which does not meet the process requirements. That is, the two process steps of bending laser welding and bending high-frequency welding are only suitable for making shells with equal wall thickness, that is, the thickness at the R corner is the same as the wall thickness. In Comparative Example 8, the difference between the outer fillet radius R of the transition section 2 and the inner fillet radius r of the transition section 2 is greater than the thickness b of the shell side wall 1, and the process is not satisfied.

[0088] For Comparative Example 3 in Table 2, when a=1.6 mm, b=1.6 mm, R=2.6 mm, and r=1 mm, regardless of which of the three manufacturing processes, hot extrusion, hot extrusion + cold drawing, or cold extrusion, is used, the following problem exists: the wall thickness is out of tolerance, that is, the thickness b of the shell side wall 1 is too large, resulting in the battery cell shell 10 being too heavy, reducing the battery cell energy density, and being unsuitable for use as a battery cell shell.

[0089] For Comparative Example 4 in Table 2, when a=0.7 mm, b=0.7 mm, R=2.5 mm, and r=1.2 mm, no matter which of the three manufacturing processes, hot extrusion, hot extrusion + cold drawing, or cold extrusion, is used, the following problem exists: Rr=2.5-1.2=1.3 mm, Rr>b, that is, the difference between the outer fillet radius R of the transition section 2 and the inner fillet radius r of the transition section 2 is too large, the transition section 2 is weak, and is prone to cracking.

[0090] For Comparative Example 5 in Table 2, the wall thickness is out of tolerance, that is, the thickness b of the shell side wall 1 is too large, resulting in excessive weight of the battery cell shell 10, which reduces the energy density of the battery cell and is not suitable for use as a battery cell shell.

[0091] For Comparative Example 6 in Table 2, the difference between the outer fillet radius R of the transition section 2 and the inner fillet radius r of the transition section 2 is too large, and the transition section 2 is weak and prone to cracking.

[0092] For Comparative Example 7 in Table 2, when a=2 mm, b=1.5 mm, R=1.5 mm, and r=1.1 mm, regardless of which of the three manufacturing processes, hot extrusion, hot extrusion + cold drawing, or cold extrusion, is used, the following problem exists: the wall thickness is excessive, that is, the thickness b of the shell side wall 1 is too large, resulting in an excessive weight of the battery cell shell 10, which reduces the energy density of the battery cell and is not suitable for use as a battery cell shell.

[0093] Comparative Example 8 in Table 2 shows that when a=1.2 mm, b=0.5 mm, R=1.5 mm, and r=0.6 mm, regardless of which of the three manufacturing processes, hot extrusion, hot extrusion + cold drawing, or cold extrusion, is used, the following problem exists: the difference between the outer fillet radius R of the transition section 2 and the inner fillet radius r of the transition section 2 is too large, making the transition section 2 weak and prone to cracking.

[0094] For Comparative Example 9 in Table 2, the wall thickness exceeds the tolerance, that is, the thickness b of the shell side wall 1 is too large, resulting in excessive weight of the battery cell shell 10, which reduces the energy density of the battery cell and is not suitable for use as a battery cell shell.

[0095] For comparative example 10 in Table 2, the difference between the outer fillet radius R of the transition section 2 and the inner fillet radius r of the transition section 2 is too large, and the transition section 2 is weak and prone to cracking.

[0096] For Comparative Example 11 in Table 3, it is shown that when a=1.3 mm, b=1.3 mm, R=2.3 mm, and r=1 mm, regardless of whether the two manufacturing processes of bending laser welding or bending high-frequency welding are used, the following problem exists: the wall thickness is out of tolerance, that is, the wall thickness is too thick, resulting in the battery cell shell 10 being too heavy, reducing the battery cell energy density, and being unsuitable for use as a battery cell shell.

[0097] For Comparative Example 12 in Table 3, it shows that: when a=0.6mm, b=0.6mm, R=2.1mm, and r=1.1mm, no matter which of the two manufacturing processes, bending laser welding or bending high-frequency welding, is used, the following problems exist: the difference between the outer fillet radius R of the transition section 2 and the inner fillet radius r of the transition section 2 is too large, which does not meet the process requirements. That is, the two process steps of bending laser welding and bending high-frequency welding are only suitable for making shells with equal wall thickness, that is, the thickness at the R corner is the same as the wall thickness. In Comparative Example 8, the difference between the outer fillet radius R of the transition section 2 and the inner fillet radius r of the transition section 2 is greater than the thickness b of the shell side wall 1, and the process does not meet the requirements.

[0098] In summary, since the battery cell housing 10 has different materials and processing techniques with different characteristics, each parameter corresponds to a different value range when using different materials or different processing techniques.

[0099] In one embodiment, at least one of the four side walls 1 is provided with an explosion-proof valve 3 , and the thickness of the side wall 1 provided with the explosion-proof valve 3 is a, and 0≤ab<1.

[0100] Since the thickness of the side wall 1 where the explosion-proof valve 3 is provided is a, and ab≥0, that is, the explosion-proof valve 3 is provided on the side wall with a larger thickness, the strength of the side wall 1 where the explosion-proof valve 3 is provided can be ensured.

[0101] Specifically, the four side walls 1 include two oppositely disposed wide surfaces and two oppositely disposed narrow surfaces, and the explosion-proof valve 3 is disposed on the narrow surface.

[0102] By providing the explosion-proof valve 3 , when thermal runaway occurs inside the battery, the explosion-proof valve 3 can be opened to release pressure and exhaust gas, thereby preventing the battery cell from catching fire or exploding due to excessive internal gas pressure.

[0103] In this embodiment, the explosion-proof valve 3 can be arranged on any narrow surface of the battery cell housing, including the explosion-proof valve 3 being arranged on one narrow surface, and also including the explosion-proof valve 3 being arranged on two narrow surfaces. Figure 2 As shown, the four side walls 1 are the first side wall 11, the second side wall 12, the third side wall 13 and the fourth side wall 14, respectively. The first side wall 11 and the third side wall 13 are arranged opposite to each other, and the second side wall 12 and the fourth side wall 14 are arranged opposite to each other. Since the width of the first side wall 11 and the third side wall 13 is significantly smaller than the width of the second side wall 12 and the fourth side wall 14, the first side wall 11 and the third side wall 13 are narrow sides, and the second side wall 12 and the fourth side wall 14 are wide sides, which can also be called large sides. The above-mentioned explosion-proof valve 3 is provided on any narrow side of the battery cell housing, that is, the explosion-proof valve 3 can be provided separately on the first side wall 11 or the third side wall 13, or can be provided on the first side wall 11 and the third side wall 13 at the same time. There can be one explosion-proof valve 3 on a single side wall 1, or multiple explosion-proof valves can be provided at intervals.

[0104] Of course, for the battery cell, the explosion-proof valve 3 can be provided on the battery cell housing 10 provided in this embodiment, or on the cover plate 20 of the battery cell, that is, the explosion-proof valve 3 is not provided on the battery cell housing 10 .

[0105] Specifically, such as Figure 7 As shown, in one embodiment, the explosion-proof valve is provided on the battery cell shell. When the battery cell is subjected to an explosion test, the battery cell shell is broken. Figure 8 As shown, the crack C is located at the R corner of the battery cell shell and is a narrow and long crack along the length direction of the battery cell shell.

[0106] Specifically, such as Figure 9 As shown, in one embodiment, the explosion-proof valve is provided on the cover plate 20 of the battery cell, and the battery cell shell is not provided with an explosion-proof valve. The battery cell is subjected to an explosion test, and the battery cell shell is ruptured, as shown in FIG. Figure 10 As shown, the crack C is located at the R corner of the battery cell shell and is a narrow and long crack along the length direction of the battery cell shell.

[0107] According to an embodiment of the present invention, in a second aspect, a battery cell 100 is further provided, comprising a pole group, a cover plate 20 and a battery cell shell 10 according to any one of the above technical solutions, wherein the pole group is arranged in the battery cell shell 10; the cover plate 20 is arranged at the end of the battery cell shell 10 to encapsulate the pole group in the battery cell shell 10.

[0108] Since the battery cell 100 includes the battery cell housing 10 of the above embodiment, the battery cell housing 10 controls the relationship between the outer fillet radius R of the transition section 2, the inner fillet radius r of the transition section 2, and the minimum thickness b of the side wall 1 within the range of Rr≤b. By specifying the parameters of the thickness of the side wall 1 of the battery cell housing and the weak point transition section 2, the fatigue resistance of the battery cell housing 10 is improved, thereby making the battery cell 100 sufficiently safe.

[0109] In addition, since the battery cell 100 includes the battery cell case 10 of the above embodiment, the battery cell 100 also has all the beneficial effects of the battery cell case 10 , which will not be described in detail here.

[0110] According to an embodiment of the present invention, in a third aspect, a battery pack is further provided, comprising the battery cell 100 in the above technical solution.

[0111] Since the battery pack includes the battery cell 100 and has the same effect as the battery cell 100 , details thereof will not be repeated here.

[0112] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cell shell, characterized in that: It includes four side walls, and adjacent side walls are connected by transition sections. The transition sections are arcs, the outer fillet radius of the transition sections is R, the inner fillet radius of the transition sections is r, and the minimum thickness of the side walls is b. Then, ; The range of the outer fillet radius R of the transition section is 0.6mm≤R≤2.5mm; At least one of the four side walls is provided with an explosion-proof valve; The thickness of the four side walls is b, and the battery cell housing is manufactured by an extrusion process and meets the following conditions: , 0.2mm≤b≤1.0mm, 0.4mm≤r≤1.6mm; Alternatively, the thickness of each of the four side walls is b, the battery cell housing is manufactured by a stamping process, and the following conditions are met: , 0.3mm≤b≤1.0mm, 0.3mm≤r≤1.6mm; Or, among the four side walls, at least one side wall has a thickness of b, and the thickness of the remaining side walls is a, and 0≤ <1, the battery cell shell is manufactured by an extrusion process and meets the following conditions: , 0.6 mm≤R≤2.5mm, 0.3mm≤a≤1.5mm, 0.2mm≤b≤1.0mm, 0.4mm≤r≤1.6mm; Or, among the four side walls, at least one side wall has a thickness of b, and the thickness of the remaining side walls is a, and 0≤ <1, the battery cell housing is manufactured by a stamping process and meets the following conditions: , 0.6 mm≤R≤2.5mm, 0.4mm≤a≤1.5mm, 0.3mm≤b≤1.0mm, 0.3mm≤r≤1.6mm.

2. The battery cell housing according to claim 1, wherein: The battery cell shell is made of aluminum, and the thickness b of the side wall of the battery cell shell is in the range of 0.3mm≤b≤1.0mm; Alternatively, the battery cell housing is made of steel, and the thickness b of the side wall of the battery cell housing is in the range of 0.3 mm ≤ b ≤ 0.5 mm.

3. The battery cell housing according to claim 1, wherein: The thickness of the side wall of the explosion-proof valve is set to a, and 0≤ <1.

4. A battery cell, characterized in that: include: The battery cell casing according to any one of claims 1 to 3; an electrode group, the electrode group being arranged in the battery cell shell; A cover plate is provided at the end of the battery cell shell to encapsulate the electrode group in the battery cell shell.

5. A battery pack, characterized in that: Including the battery cell according to claim 4.

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