Housing members, battery cells, batteries and power consuming devices

Abstract

The embodiments of the present application provide a housing member, a battery cell, a battery, and a power consuming device, in which the housing member includes a non-weakened area and a weak area integrally molded, a groove is provided in the housing member, the non-weakened area is formed around the groove, and the weak area is formed at the bottom of the groove, and the weak area is configured to be broken when the battery cell releases internal pressure, in which the average grain size of the weak area is S1, the average grain size of the non-weakened area is S2, and S1 / S2≦0.9. The average grain size of the weak area is reduced to improve the mechanical performance of the material of the weak area, improve the toughness and fatigue resistance strength of the weak area, reduce the risk of the weak area being broken under normal use conditions of the battery cell, and extend the service life of the battery cell.

Description

[Technical field]

[0001] The present application relates to the field of battery technology, and in particular to housing members, battery cells, batteries and power consuming devices. [Background technology]

[0002] With the development of new energy technology, the applications of batteries are becoming more and more widespread, such as in mobile phones, notebook computers, battery cars, electric cars, electric airplanes, electric steamships, electric toy cars, electric toy steamships, electric toy airplanes and electric tools.

[0003] In the development of battery technology, in addition to improving the safety of battery cells, the service life of battery cells is also an issue that must be considered. Therefore, how to extend the service life of battery cells is an issue that needs to be resolved quickly in battery technology. Summary of the Invention

[0004] The embodiments of the present application provide a housing member, a battery cell, a battery, and a power consuming device that can effectively extend the service life of a battery.

[0005] According to a first aspect, an embodiment of the present application provides a housing member for a battery cell, the housing member including a non-weakened area and a weak area that are integrally molded, the housing member having a groove, the non-weakened area formed around the groove, and the weak area formed at a bottom of the groove, the weak area configured to break when the battery cell releases internal pressure, wherein an average crystal grain size of the weak area is S1 and an average crystal grain size of the non-weakened area is S2, and the housing member satisfies S1 / S2≦0.9.

[0006] In the above technical proposal, S1 / S2≦0.9, so the difference between the average grain size in the brittle area and the average grain size in the non-weakened area is large, which reduces the average grain size in the brittle area, improves the mechanical performance of the material in the brittle area, improves the toughness and fatigue resistance strength of the brittle area, reduces the risk of the brittle area being destroyed under normal usage conditions of the battery cell, and extends the service life of the battery cell.

[0007] In some embodiments, S1 / S2 is ≧0.05. If S1 / S2 is too small, the weak area is difficult to form, and the strength of the weak area is too large, so that the weak area is difficult to break when the battery cell experiences thermal runaway, and the pressure is easily not released in a timely manner. Therefore, if S1 / S2 is ≧0.05, the difficulty of forming the weak area is reduced, and the pressure is quickly released when the battery cell experiences thermal runaway.

[0008] In some embodiments, 0.1≦S1 / S2≦0.5, so as to ensure that the overall performance of the housing members is better and the weak area can be broken in a timely manner when the battery cell experiences thermal runaway, while ensuring that the weak area has sufficient strength under normal use conditions of the battery cell.

[0009] In some embodiments, 0.4 μm≦S1≦75 μm. If S1 is too large, the toughness and fatigue resistance strength of the weak region are poor, while if S1 is too small, the difficulty of forming the weak region is high, and the strength of the weak region is too large, making it more difficult for the weak region to be destroyed during thermal runaway of the battery cell, and making it easy for the pressure to be released in a timely manner. Therefore, by making 0.4 μm≦S1≦75 μm, the difficulty of forming the weak region is reduced, the timeliness of pressure release during thermal runaway of the battery cell is improved, and the toughness and fatigue resistance strength of the weak region are improved, reducing the risk of the weak region being destroyed under normal use conditions of the battery cell.

[0010] In some embodiments, 1 μm≦S1≦10 μm, so as to ensure that the overall performance of the housing member is better, the weak area can be broken in a timely manner when the battery cell experiences thermal runaway, and the weak area has sufficient strength under normal use conditions of the battery cell.

[0011] In some embodiments, 10 μm≦S2≦150 μm.

[0012] In some embodiments, 30 μm≦S2≦100 μm.

[0013] In some embodiments, the minimum thickness of the weak region is A, and satisfies 1≦A / S1≦100. If A / S1 is too small, the number of grain layers in the weak region in the thickness direction of the weak region is small, and the fatigue resistance strength of the weak region is too small. On the other hand, if A / S1 is too large, the number of grain layers in the weak region in the thickness direction of the weak region is too large, and the strength of the weak region is too large, which is likely to cause the risk that the weak region cannot be broken in a timely manner when the battery cell experiences thermal runaway. Therefore, 1≦A / S1≦100, the number of grain layers in the thickness direction of the weak region is large, which improves the fatigue resistance strength of the weak region and reduces the risk that the weak region will be broken under normal use conditions of the battery cell, and also allows the weak region to be broken in a timely manner when the battery cell experiences thermal runaway, thereby achieving the purpose of timely pressure relief.

[0014] In some embodiments, 5≦A / S1≦20, which ensures that the overall performance of the housing members is better, the weak areas can be broken in a timely manner when the battery cell experiences thermal runaway, and the weak areas have sufficient fatigue resistance strength under normal use conditions of the battery cell, thereby extending the service life of the battery cell.

[0015] In some embodiments, the minimum thickness of the weak area is A, the hardness of the weak area is H1, and satisfies 5HBW / mm≦H1 / A≦10000HBW / mm. Taking into consideration the effect of the thickness of the weak area on the performance of the housing member, and the effect of the hardness of the weak area on the performance of the housing member, 5HBW / mm≦H1 / A≦10000HBW / mm, the weak area can have sufficient strength under normal use conditions of the battery cell, the weak area is not easily destroyed by fatigue, the service life of the battery cell can be extended, and the housing member can timely release pressure through the weak area when the battery cell experiences thermal runaway, reducing the risk of the battery cell exploding and improving the safety of the battery cell.

[0016] In some embodiments, 190HBW / mm≦H1 / A≦4000HBW / mm, which ensures that the overall performance of the housing members is better, the weak areas can be broken in a timely manner when the battery cell experiences thermal runaway, and the weak areas have sufficient strength under normal use conditions of the battery cell, thereby extending the service life of the battery cell under the premise of ensuring the safety of the battery cell.

[0017] In some embodiments, 0.02mm≦A≦1.6mm. If A is too small, it is difficult to mold the weak area, and the weak area is likely to be damaged during the molding process. On the other hand, if A is too large, it is difficult for the weak area to be destroyed when the battery cell experiences thermal runaway, and pressure relief is likely to be in a timely manner. Therefore, 0.02mm≦A≦1.6mm is set to reduce the difficulty of molding the pressure relief area and improve the promptness of pressure relief when the battery cell experiences thermal runaway.

[0018] In some embodiments, 0.06 mm≦A≦0.4 mm. This further reduces the difficulty of molding the pressure relief area and improves the instantaneous pressure relief in the event of thermal runaway of the battery cell.

[0019] In some embodiments, the hardness of the weakened area is H1, and the hardness of the non-weakened area is H2, where H1>H2, which corresponds to increasing the hardness of the weakened area, thereby increasing the strength of the weakened area, and reducing the risk that the weakened area will be broken under normal use conditions of the battery cell.

[0020] In some embodiments, H1 / H2≦5. If H1 / H2 is too large, it may occur that the weak area is very difficult to destroy during thermal runaway of the battery cell. Therefore, H1 / H2≦5 reduces the risk that the weak area cannot be destroyed in a timely manner during thermal runaway of the battery cell, and improves the safety of the battery cell.

[0021] In some embodiments, H1 / H2≦2.5.

[0022] In some embodiments, 5HBW≦H2≦150HBW.

[0023] In some embodiments, 5HBW≦H1≦200HBW.

[0024] In some embodiments, the minimum thickness of the weak region is A, and the minimum thickness of the non-weak region is B, and 0.05≦A / B≦0.95 is satisfied. If A / B is too small, the strength of the weak region may be insufficient. If A / B is too large, the weak region may not be easily destroyed during thermal runaway of the battery cell, and the pressure may not be released in a timely manner, increasing the probability of the battery cell exploding. Therefore, 0.05≦A / B≦0.95 can reduce the probability of the weak region exploding under normal use conditions of the battery cell, and can also reduce the probability of the battery cell exploding during thermal runaway.

[0025] In some embodiments, 0.12≦A / B≦0.8. In this way, the overall performance of the housing members is better, and the weak area can be broken in a timely manner when the battery cell experiences thermal runaway, while ensuring that the weak area has sufficient strength under normal use conditions of the battery cell.

[0026] In some embodiments, 0.2≦A / B≦0.5.

[0027] In some embodiments, 0.02 mm≦A≦1.6 mm.

[0028] In some embodiments, 0.06 mm≦A≦0.4 mm.

[0029] In some embodiments, 1 mm≦B≦5 mm. When B is too large, the thickness of the non-weakened area is large, the material of the housing member is larger, the mass of the housing member is large, and the economic efficiency is poor. When B is too small, the thickness of the non-weakened area is small, and the deformation resistance of the housing member is poor. Therefore, when 1 mm≦B≦5 mm, the housing member has good economic efficiency and good deformation resistance.

[0030] In some embodiments, 1.2 mm≦B≦3.5 mm, so that the housing members have better economy and deformation resistance.

[0031] In some embodiments, 2 mm≦B≦3 mm.

[0032] In some embodiments, the housing member has a pressure relief area, the groove portion includes a one-stage notch, the notch is disposed along an edge of the pressure relief area, the pressure relief area is configured to be openable across the notch, and the weakened area forms a bottom of the notch, and when the weakened area is broken, the pressure relief area is openable across the weakened area to achieve pressure relief and increase the pressure relief area of ​​the housing member.

[0033] In some embodiments, the housing member has a first surface and a second surface disposed opposite to each other, and the notch is recessed from the first surface toward the second surface. The notch is a groove and has a simple structure. The notch can be molded in the first surface during molding, which simplifies molding, improves production efficiency, and reduces production costs.

[0034] In some embodiments, the housing member includes a first surface and a second surface disposed opposite to each other, the groove portion includes a multi-stage groove, the multi-stage grooves are disposed on the housing member in sequence along a direction from the first surface to the second surface, and the weakened area is formed at a bottom of a stage of the groove farthest from the first surface, and the housing member has a pressure relief area, and the grooves of each stage are disposed along an edge of the pressure relief area, and the pressure relief area is configured to open at the stage of the groove farthest from the first surface. During molding, the multi-stage grooves can be molded in the housing member one stage at a time, and the molding depth of each stage of the groove can be reduced, thereby reducing the molding force that the housing member receives when molding the grooves of each stage, reducing the risk of cracks occurring in the housing member, and the housing member is less likely to fail due to cracks occurring at the positions where the grooves are disposed, thereby extending the service life of the housing member.

[0035] In some embodiments, the groove portion includes a multi-stage groove that is formed in a direction from the first surface toward the second surface, and the groove portion includes a multi-stage groove that is formed gradually in a direction from the first surface toward the second surface during molding.

[0036] In some embodiments, the housing member includes a first surface and a second surface disposed opposite to each other, the groove portion further includes a one-stage countersunk groove, the countersunk groove is recessed in a direction from the first surface toward the second surface, and the pressure relief area is formed in the groove bottom wall of the countersunk groove. The countersunk groove can reduce the depth of the notched groove while ensuring a constant thickness of the final weakened area, thereby reducing the molding force that the housing member receives when molding the notched groove, and reducing the risk of cracking the housing member. Note that the countersunk groove can provide an escape space during the process of opening to the pressure relief area, and even if the first surface is blocked by an obstacle, the pressure relief area can still open to relieve pressure.

[0037] In some embodiments, the housing member includes a first surface and a second surface that are disposed opposite to each other, and the groove portion further includes a multi-stage countersunk groove, and the multi-stage countersunk grooves are sequentially disposed on the housing member along a direction from the first surface to the second surface, and the countersunk groove of the stage furthest from the second surface is recessed in a direction from the first surface to the second surface, and the pressure relief area is formed on the groove bottom wall of the countersunk groove of the stage furthest from the first surface. When forming the multi-stage countersunk groove, the forming depth of each stage of the countersunk groove can be reduced, and the forming force that the housing member receives when forming the countersunk groove of each stage can be reduced, and the risk of cracking the housing member can be reduced. In addition, the multi-stage countersunk groove can provide an escape space in the process of opening to the pressure relief area, and even if the first surface is blocked by an obstacle, the pressure relief area can still open to relieve pressure.

[0038] In some embodiments, the inner space of the countersunk groove is a cylinder, a prism, a truncated cone, or a truncated pyramid, which has a simple structure, is easy to mold, and can provide more escape space in the process of opening to the pressure relief area.

[0039] In some embodiments, the score groove includes a first groove section and a second groove section, the first groove section and the second groove section intersect and are located along an edge of the pressure relief area. Stress is concentrated at the intersection of the first groove section and the second groove section such that the weakened area may be initially broken at the intersection of the first groove section and the second groove section. When the explosion pressure of the battery cell is constant, the weakened area may be thicker and the forming depth of the score groove may be smaller.

[0040] In some embodiments, the notched groove further includes a third groove section, the first groove section and the third groove section are disposed opposite to each other, the second groove section and the third groove section intersect, and the first groove section, the second groove section and the third groove section are disposed along the edge of the pressure relief area. In this way, the pressure relief area can be opened with the first groove section, the second groove section and the third groove section as boundaries, so that when the battery cell is pressure relieved, the pressure relief area can be more easily opened, and a large-area pressure relief of the housing member can be realized.

[0041] In some embodiments, the first groove section, the second groove section and the third groove section are connected in sequence to define a pressure relief area.

[0042] In some embodiments, the first groove section, the second groove section and the third groove section define two pressure relief areas respectively located on both sides of the second groove section, and the two pressure relief areas can be split in half and opened to relieve pressure, which can effectively improve the pressure relief efficiency of the housing member.

[0043] In some embodiments, the scored groove is a groove that extends along a non-closing path, and the pressure relief area can open in an inverted manner and eventually merge with other areas of the housing member after opening, reducing the risk of spatter generation after the pressure relief area opens.

[0044] In some embodiments, the notch groove is a circular arc groove. The circular arc groove has a simple structure and is easy to mold. In the pressure relief process, the pressure relief area can be rapidly ruptured along the circular arc groove, so that the pressure relief area can be rapidly opened.

[0045] In some embodiments, the scored groove is a groove that extends along a closing locus, and during the pressure relief process, the housing member can rupture along the scored groove, thereby opening to allow the pressure relief area to separate, increasing the pressure relief area of ​​the housing member and improving the pressure relief speed of the housing member.

[0046] In some embodiments, the scored groove is an annular groove, which is simple in structure and easy to mold, and during the pressure relief process, the housing member can be rapidly ruptured along the annular groove so that the pressure relief area can be rapidly opened.

[0047] In some embodiments, the area of ​​the pressure relief region is D and is 90 mm 2 ≦D≦1500mm 2 If D is too small, the pressure release area of ​​the housing member is small, and the pressure release time during thermal runaway of the battery cell is poor. On the other hand, if D is too large, the impact resistance of the pressure release area is poor, the pressure release area is greatly deformed after being subjected to force, and the fragile area is easily broken under normal use conditions of the battery cell, which affects the service life of the battery cell. Therefore, the 90mm 2 ≦D≦1500mm 2 In this case, the service life of the battery cell can be extended and the safety of the battery cell can be improved.

[0048] In some embodiments, 150 mm 2 ≦D≦1200mm 2 It is.

[0049] In some embodiments, 200 mm 2 ≦D≦1000mm 2 It is.

[0050] In some embodiments, 250 mm 2 ≦D≦800mm 2 It is.

[0051] In some embodiments, the housing member has a first surface and a second surface disposed opposite each other, the groove is recessed from the first surface toward the second surface, the groove forms an outer edge in the first surface, and a region of the housing member that is more than a predetermined distance away from the outer edge is a non-weakened region, such that the non-weakened region is less affected by the process of forming the groove, thereby resulting in more uniform grains in the non-weakened region.

[0052] In some embodiments, the preset distance is L, satisfying L=5 mm.

[0053] In some embodiments, the housing member further includes a transition region, the transition region connecting the weakened region and the non-weakened region, and the average grain size of the transition region is S3, where S3≦S2. The transition region serves to connect the weakened region and the non-weakened region, and realizes the integral molding of the weakened region and the non-weakened region.

[0054] In some embodiments, the housing member is an end cap, which is used to close the opening of the case, and the case is used to accommodate the electrode assembly, so that the end cap has a pressure relief function and ensures the safety of the battery cell.

[0055] In some embodiments, the housing member is a case having an opening for accommodating the electrode assembly, whereby the case has a pressure relief function and ensures the safety of the battery cells.

[0056] In some embodiments, the case includes a plurality of integrally molded walls that cooperate to define an interior space of the case, at least one of the walls being provided with a groove, the plurality of walls being integrally molded such that the wall in which the groove is provided has a high degree of reliability.

[0057] In some embodiments, the plurality of walls includes a bottom wall and a plurality of side walls circumscribing the periphery of the bottom wall, the case having an opening at an end opposite the bottom wall, a groove in the bottom wall, and / or a groove in at least one of the side walls.

[0058] In some embodiments, the case is a rectangular parallelepiped, which can be applied to a rectangular battery cell and meet the large capacity requirements of the battery cell.

[0059] In some embodiments, the material of the housing member includes an aluminum alloy, which has a light weight, good ductility, and is easy to mold.

[0060] In some embodiments, the aluminum alloy includes aluminum≧99.6%, copper≦0.05%, iron≦0.35%, magnesium≦0.03%, manganese≦0.03%, silicon≦0.25%, titanium≦0.03%, vanadium≦0.05%, zinc≦0.05%, and other single elements≦0.03% by weight. Such aluminum alloys have lower hardness and better forming ability, which reduces the difficulty of forming the groove, improves the forming precision of the groove, and improves the pressure relief consistency of the housing members.

[0061] In some embodiments, the aluminum alloy includes, by weight, ≧96.7% aluminum, 0.05%≦copper≦0.2% iron≦0.7% manganese≦1.5% silicon≦0.6% zinc≦0.1% other single elemental content≦0.05% by weight, and other total elemental content≦0.15% by weight. Housing members made of such aluminum alloys have higher hardness, higher strength, and better fracture resistance.

[0062] According to a second aspect, an embodiment of the present application provides a battery cell including a housing member according to any one of the embodiments of the first aspect above.

[0063] In some embodiments, the battery cell further includes a case for housing the electrode assembly, the case having an opening, and the housing member is an end cap closing the opening.

[0064] In some embodiments, the housing member is a case having an opening for housing the electrode assembly, and the battery cell further includes an end cap closing the opening.

[0065] According to a third aspect, an embodiment of the present application provides a battery including a battery cell according to any one of the embodiments of the second aspect above.

[0066] In some embodiments, the weak area is located at the bottom of the battery cell, and during use of the battery, the weak area is subjected to a large force under the action of gravity of the electrode assembly and electrolyte inside the battery cell, and the weak area and the non-weak area are integrally formed, so that the weak area has excellent structural strength, high reliability, and prolongs the service life of the battery cell.

[0067] In some embodiments, the battery cell includes a case, the case is adapted to house the electrode assembly, the case includes a bottom wall and a plurality of side walls surrounding the periphery of the bottom wall, the bottom wall and the side walls are integrally molded, the case has an opening formed at an end opposite the bottom wall, and the weakened area is located in the bottom wall.

[0068] In some embodiments, the battery cell includes an end cap, the end cap is adapted to close an opening in the case, the case is adapted to house the electrode assembly, and the weakened area is located in the end cap.

[0069] According to a fourth aspect, an embodiment of the present application provides a power consumer device including a battery according to any one of the embodiments of the third aspect above.

[0070] In order to more clearly describe the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and should not be considered as limiting the scope, and those skilled in the art can obtain other related drawings based on these drawings without making creative efforts. [Brief description of the drawings]

[0071] [Figure 1] 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application. [Diagram 2] FIG. 2 is an exploded view of a battery according to some embodiments of the present application. [Diagram 3] FIG. 2 is an exploded view of a battery cell according to some embodiments of the present application. [Figure 4] 2 is a structural schematic diagram of a housing member according to some embodiments of the present application. [Diagram 5] 5 is a cross-sectional view taken along the line CC of the housing member shown in FIG. [Figure 6] 6 is a grain diagram (schematic diagram) of the housing member shown in FIG. 5. [Figure 7] 6 is a local enlarged view of a portion E of the housing member shown in FIG. 5. [Figure 8] 11 is a close-up view of a housing member according to some further embodiments of the present application. [Figure 9] 13 is a structural schematic diagram of a housing member according to still further some embodiments of the present application (showing a one-step notched groove). [Figure 10] 10 is an E-E cross-sectional view of the housing member shown in FIG. [Figure 11] 11A-11C are structural schematic diagrams of housing members according to further some embodiments of the present application (showing one-step notched grooves). [Figure 12] 12 is a cross-sectional view of the housing member shown in FIG. 11 FF. [Figure 13] 11 is a structural schematic diagram of a housing member according to some further embodiments of the present application (showing a one-step notched groove). [Figure 14] 14 is a cross-sectional view of the housing member shown in FIG. 13 along G-G line. [Figure 15] 13 is a structural schematic diagram of a housing member according to still further some embodiments of the present application (showing two-stage notched grooves). [Figure 16] 16 is a KK cross-sectional view of the housing member shown in FIG. 15. [Figure 17] 11A-11C are structural schematic diagrams of housing members according to further some embodiments of the present application (showing two-stage notched grooves). [Figure 18] 18 is an MM cross-sectional view of the housing member shown in FIG. 17. [Figure 19] 11 is a structural schematic diagram of a housing member according to some further embodiments of the present application (showing two-stage notched grooves). [Figure 20]20 is a cross-sectional view of the housing member shown in FIG. 19 taken along line N-N. [Figure 21] 2 is a perspective view of a housing member according to some embodiments of the present application. FIG. [Figure 22] 22 is a structural schematic diagram of the housing member shown in FIG. 21 (showing one-stage notched groove and one-stage countersunk groove). FIG. [Diagram 23] 23 is a cross-sectional view of the housing member shown in FIG. 22 . [Figure 24] 11A-11C are structural schematic diagrams of housing members according to further some embodiments of the present application (showing one-step notched grooves and one-step countersunk grooves). [Diagram 25] 25 is a PP cross-sectional view of the housing member shown in FIG. 24. [Figure 26] 11 is a structural schematic diagram of a housing member according to some further embodiments of the present application (showing a one-step notched groove and a one-step countersunk groove). FIG. [Figure 27] 27 is a QQ cross-sectional view of the housing member shown in FIG. 26. [Figure 28] 1 is a structural schematic diagram of a housing member according to some embodiments of the present application (showing a one-stage notched groove and a two-stage countersunk groove); [Figure 29] 29 is a cross-sectional view of the housing member shown in FIG. 28 taken along the line RR. [Diagram 30] 11A-11C are structural schematic diagrams of housing members according to further some embodiments of the present application (showing a one-step notched groove and a two-step countersunk groove); [Diagram 31] 31 is a SS cross-sectional view of the housing member shown in FIG. 30. [Diagram 32] 11 is a structural schematic diagram of a housing member according to some further embodiments of the present application (showing a one-step notched groove and a two-step countersunk groove). FIG. [Diagram 33] 33 is a cross-sectional view of the housing member shown in FIG. 32 . [Diagram 34] 1 is a structural schematic diagram of a housing member according to some embodiments of the present application (showing a one-stage V-shaped notched groove); [Diagram 35] FIG. 11 is a structural schematic diagram of a housing member according to another embodiment of the present application. [Diagram 36]4 is a grain diagram (schematic diagram) of a housing member according to some further embodiments of the present application. [Figure 37] 1 is a structural schematic diagram of an end cap according to some embodiments of the present application. [Figure 38] 1 is a structural schematic diagram of a case according to some embodiments of the present application. [Figure 39] 4 is a structural schematic diagram of a case according to some other embodiments of the present application. FIG. [Diagram 40] 1 is a structural schematic diagram of a battery cell according to some embodiments of the present application. [Explanation of symbols]

[0072] 1 - housing, 11 - end cap, 12 - case, 121 - wall, 121a - side wall, 121b - bottom wall, 2 - electrode assembly, 21 - positive tab, 22 - negative tab, 3 - positive electrode terminal, 4 - negative electrode terminal, 5 - housing member, 51 - non-weakened area, 511 - inner edge, 52 - weakened area, 53 - groove, 531 - groove bottom surface of groove, 532 - notched groove, 532a - outermost one step notched groove, 532b - innermost one step notched groove, 5321 - first groove section, 5 322-second groove section, 5323-third groove section, 533-countersink groove, 533a-outermost single stage countersink groove, 533b-innermost single stage countersink groove, 5331-countersink groove bottom wall, 534-outer edge, 54-first surface, 55-second surface, 56-pressure relief area, 57-transition area, 10-battery cell, 20-housing, 201-first part, 202-second part, 100-battery, 200-controller, 300-motor, 1000-vehicle, Y-intermediate plane. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained based on the embodiments of the present application without the need for creative efforts by those skilled in the art are all within the scope of protection of the present application.

[0074] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art in the technical field of this application, the terms used in the specification of this application are only for describing specific embodiments and are not intended to limit this application, and the terms "comprise", "have" and any variations thereof in the specification, claims and the brief description of the drawings of this application are intended to cover non-exclusive "comprise". The terms "first", "second", etc. in the specification, claims or the drawings of this application are not intended to describe a specific order or subordinate relationship, but are intended to distinguish different objects.

[0075] An "embodiment" referred to in this application means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they mutually exclusive separate or alternative embodiments of other embodiments.

[0076] The term "and / or" in this application merely describes the relationship between related objects and indicates that three relationships may exist, for example, A and / or B may represent three cases: A alone, A and B in combination, and B alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "or" relationship.

[0077] In the embodiments of the present application, the same reference numerals represent the same elements, and for the sake of brevity, detailed descriptions of the same elements in different embodiments are omitted. It should be understood that the thickness, length, width, etc. of various elements in the embodiments of the present application shown in the drawings, and the overall thickness, length, width, etc. of the integrated device are illustrative descriptions, and should not be construed as any limitation to the present application.

[0078] The term "plurality" as used herein refers to two or more (including two).

[0079] In the embodiments of the present application, the battery cell may be a secondary battery, which refers to a battery cell that can be continuously used after being discharged by activating the active material through charging.

[0080] The battery cells may be lithium ion batteries, sodium ion batteries, sodium lithium ion batteries, lithium metal batteries, sodium metal batteries, lithium sulfur batteries, magnesium ion batteries, nickel metal hydride batteries, nickel cadmium batteries, lead acid batteries, etc., and examples of the present application are not limited thereto.

[0081] The battery referred to in the embodiments of the present application may include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or series-parallel via busbar members.

[0082] In some embodiments, the battery may be a battery module, where multiple battery cells are secured together to form a battery module.

[0083] In some embodiments, the battery may be a battery pack, the battery pack including a housing and battery cells, the battery cells or modules being housed in the housing.

[0084] In some embodiments, the housing may be part of a chassis structure of a vehicle, for example, the housing portion may be at least a portion of the floor of the vehicle, or at least a portion of the transverse and longitudinal beams of the vehicle.

[0085] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage electrical cabinet, and the like.

[0086] The development of battery technology requires simultaneous consideration of a wide range of design factors, such as performance parameters such as energy density, cycle life, discharge capacity, and charge / discharge ratio, as well as battery safety.

[0087] In a battery cell, a pressure relief mechanism can be installed in the housing of the battery cell to ensure the safety of the battery cell. In the event of thermal runaway of the battery cell, the pressure relief mechanism releases the pressure inside the battery cell, thereby improving the safety of the battery cell.

[0088] In a typical battery cell, the pressure relief mechanism is welded to the housing so as to fix the pressure relief mechanism to the housing. For example, the pressure relief mechanism is an explosion-proof plate installed on the end cap of the housing. When the battery cell thermally runs away, the explosion-proof plate is destroyed and the waste material inside the battery cell is discharged, thereby achieving the purpose of releasing the pressure inside the battery cell. Since the pressure relief mechanism is welded to the housing, and cracks may occur at the welded position during long-term use of the battery cell, the strength of the welded position is reduced, and when the pressure inside the battery cell does not reach the explosion pressure of the pressure relief mechanism, the welded position is easily destroyed, which leads to failure of the pressure relief mechanism and low reliability of the pressure relief mechanism.

[0089] In order to improve the reliability of the pressure relief mechanism, the inventors have found through research that the pressure relief mechanism and the housing can be made into an integrally molded structure, that is, a part of the housing can be made into the pressure relief mechanism. For example, by performing a weakening treatment on a local part of the end cap, the strength of the local part of the end cap can be reduced to form a weak area, thereby forming an integral pressure relief mechanism, and thus the reliability of the pressure relief mechanism can be effectively improved.

[0090] The inventors discovered that after forming an integrated pressure relief mechanism in the housing, the mechanical performance of the weak area of ​​the housing is poor, and under normal usage conditions of the battery cell, fatigue fracture is likely to occur in the weak area due to long-term changes in the internal pressure of the battery cell, which will affect the service life of the battery cell.

[0091] Therefore, an embodiment of the present application provides a housing member, and a groove is provided in the housing member to form a non-weakened area and a weak area that are integrally molded, the non-weakened area is formed around the groove and the weak area is formed at the bottom of the groove, the average crystal grain size of the weak area is S1, the average crystal grain size of the non-weakened area is S2, and S1 / S2≦0.9.

[0092] In such a housing member, S1 / S2≦0.9, the average grain size of the weak region is reduced, the mechanical performance of the material in the weak region is improved, the toughness and fatigue resistance strength of the weak region are improved, the risk of the weak region being destroyed under normal use conditions of the battery cell is reduced, and the service life of the battery cell is extended.

[0093] The technical solutions described in the embodiments of the present application are applicable to batteries and power-consuming devices that use batteries.

[0094] The power consumption devices may be vehicles, mobile phones, portable devices, notebook computers, steamships, spacecraft, electric toys and power tools, etc. The vehicles may be fuel oil vehicles, gas vehicles or new energy vehicles, the new energy vehicles may be pure electric vehicles, hybrid vehicles or range extender vehicles, etc., the spacecraft include airplanes, rockets, space shuttles and spaceships, etc., the electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric steamship toys and electric airplane toys, etc., and the electric tools include metal cutting power tools, polishing power tools, assembly power tools and railway power tools, such as electric drills, electric grinders, electric wrenches, electric drivers, electric hammers, hammer drills, concrete vibrators and electric planers, etc. The embodiments of the present application do not particularly limit the above power consumption devices.

[0095] For convenience of explanation, the following embodiment will be described by taking an example in which the power consuming device is a vehicle.

[0096] 1, which is a structural schematic diagram of a vehicle 1000 according to some embodiments of the present application. A battery 100 is installed inside the vehicle 1000, and the battery 100 may be installed at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000, for example, the battery 100 can be an operating power source for the vehicle 1000.

[0097] The vehicle 1000 may further include a controller 200 and a motor 300, where the controller 200 is for powering the motor 300 and controlling the battery 100 for use in, for example, starting, navigating and running operating power consumption needs of the vehicle 1000.

[0098] In some embodiments of the present application, the battery 100 can provide not only the operating power source for the vehicle 1000, but also the propulsion power for the vehicle 1000, either in place of or in place of fuel oil or natural gas as the propulsion power source for the vehicle 1000.

[0099] 2, which is an exploded view of a battery 100 according to some embodiments of the present application. The battery 100 includes a battery cell 10 and a housing 20, where the housing 20 is used to house the battery cell 10.

[0100] Here, the housing 20 is a member that houses the battery cell 10, provides an arrangement space for the battery cell 10, and can adopt various structures. In some embodiments, the housing 20 may include a first part 201 and a second part 202, and the first part 201 and the second part 202 are placed over each other to define an arrangement space for storing the battery cell 10. The first part 201 and the second part 202 may have various shapes, for example, a rectangular parallelepiped, a cylindrical body, etc. The first part 201 may be a hollow structure that is open on one side, and the second part 202 may be a hollow structure that is open on one side, and the open side of the second part 202 is placed over the open side of the first part 201 to form the housing 20 having the arrangement space. The first part 201 may be a hollow structure that is open on one side, and the second part 202 may be a plate-shaped structure that is placed over the open side of the first part 201 to form the housing 20 having the arrangement space. For example, the battery cell 10 may be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell 10 of other shapes, where the prismatic battery cell includes a rectangular housing battery cell, a blade battery cell, a polygonal prismatic battery, and the polygonal prismatic battery is, for example, a hexagonal prismatic battery, and the like, and the present application is not particularly limited thereto.

[0101] In the battery 100, the battery cell 10 may be one or more. When there are more than one battery cell 10, the battery cells 10 may be connected in series, parallel, or series-parallel, and series-parallel connection means that the battery cells 10 are connected in series or parallel. A battery module may be formed by first connecting the battery cells 10 in series, parallel, or series-parallel, and then the battery modules may be connected in series, parallel, or series-parallel as a whole and housed in the housing 20. All the battery cells 10 may be directly connected in series, parallel, or series-parallel, and then the whole consisting of all the battery cells 10 may be housed in the housing 20.

[0102] 3, which is an exploded view of a battery cell 10 according to some embodiments of the present application. The battery cell 10 may include a housing 1 and an electrode assembly 2.

[0103] The housing 1 is used to house components such as the electrode assembly 2 and the electrolyte. The housing 1 may be a steel case, an aluminum case, a plastic case (e.g., polypropylene), a composite metal case (e.g., a copper-aluminum composite housing), or an aluminum-plastic film, etc. As an example, the housing 1 may include a case 12 and an end cap 11.

[0104] The case 12 may have a hollow structure with an opening at one end or with openings at both opposing ends. The material of the case 12 may be a variety of materials such as copper, iron, aluminum, steel, and aluminum alloy.

[0105] The end cap 11 is a member that closes the opening of the case 12 to isolate the internal environment of the battery cell 10 from the external environment. The end cap 11 and the case 12 cooperate to define an accommodation space for accommodating the electrode assembly 2, the electrolyte, and other components. The end cap 11 may be connected to the case 12 by welding or seaming to close the opening of the case 12. The shape of the end cap 11 may match the shape of the housing 1. For example, the end cap 11 has a rectangular plate-like structure that fits the housing 1 when the case 12 has a rectangular parallelepiped structure, and also has a circular plate-like structure that fits the case 12 when the case 12 has a cylindrical structure. The material of the end cap 11 may be a variety of materials, such as copper, iron, aluminum, steel, and aluminum alloy.

[0106] The battery cell 10 may have one or two end caps 11. In an embodiment in which the case 12 is a hollow structure with openings formed at both ends, two end caps 11 may be provided, and the two end caps 11 close the two openings of the case 12, respectively, and the two end caps 11 and the case 12 cooperate to define the storage space. In an embodiment in which the case 12 is a hollow structure with an opening formed at one end, one end cap 11 may be provided, and the opening at one end of the case 12 is closed, and the one end cap 11 and the case 12 cooperate to define the storage space.

[0107] The electrode assembly 2 includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell 10, active ions (e.g., lithium ions) shuttle between the positive electrode and the negative electrode to absorb and release. The separator is disposed between the positive electrode and the negative electrode, and serves to prevent short-circuiting between the positive and negative electrodes and allows the active ions to pass through.

[0108] In some examples, the positive electrode may be a positive plate, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0109] For example, a positive electrode current collector has two opposing surfaces in the thickness direction of the positive electrode current collector, and a positive electrode active material is disposed on either one or both of the two opposing surfaces of the positive electrode current collector.

[0110] For example, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, the metal foil sheet may be aluminum or stainless steel with silver surface treatment, stainless steel, copper, aluminum, nickel, graphite electrode, carbon, nickel, or titanium. The composite current collector may include a polymer base layer and a metal layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0111] As an example, the positive electrode active material may include at least one of lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of the lithium-containing phosphate may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM 523(may be abbreviated as LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (may be abbreviated as LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2) and modifying compounds thereof, etc.

[0112] In some embodiments, the positive electrode may be a metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. When the metal foam is used as the positive electrode, the positive electrode active material may not be provided on the surface of the metal foam, or may be provided on the surface of the metal foam. For example, a lithium source material, potassium metal or sodium metal may be filled or deposited in the metal foam, and the lithium source material is lithium metal and / or a lithium-rich material.

[0113] In some examples, the negative electrode may be a negative electrode plate, which may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0114] For example, the negative electrode current collector has two opposing surfaces in the thickness direction of the negative electrode current collector, and the negative electrode active material is disposed on either one or both of the two opposing surfaces of the negative electrode current collector.

[0115] For example, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, the metal foil sheet may be aluminum or stainless steel with silver surface treatment, stainless steel, copper, aluminum, nickel, graphite electrode, carbon, nickel, or titanium. The composite current collector may include a polymer base layer and a metal layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene).

[0116] For example, the negative electrode active material may be a negative electrode active material for batteries known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicone-based material, tin-based material, and lithium titanate. The silicone-based material may be selected from at least one of silicone alone, silicone oxide, silicone carbon composite, silicone nitrogen composite, and silicone alloy. The tin-based material may be selected from at least one of tin alone, tin oxide, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0117] In some embodiments, the negative electrode may be a metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, carbon foam, etc. When the metal foam is used as the negative electrode plate, the negative electrode active material may not be provided on the surface of the metal foam, or may be provided on the surface of the metal foam.

[0118] As an example, a lithium source material, potassium metal or sodium metal may be loaded or / and deposited in the negative electrode current collector, the lithium source material being lithium metal and / or a lithium-rich material.

[0119] In some examples, the material of the positive current collector can be aluminum and the material of the negative current collector can be copper.

[0120] In some embodiments, the electrode assembly 2 further includes a separator, which is disposed between the positive electrode and the negative electrode.

[0121] In some embodiments, the separator is a separator film. The present application is not particularly limited to the type of separator film, and any known porous structure separator film with good chemical stability and mechanical stability may be selected.

[0122] For example, the main material of the separator film may be at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The separator film may be a single layer film or a multi-layer composite film, and there is no particular restriction. When the separator film is a multi-layer composite film, the materials of each layer may be the same or different, and there is no particular restriction. The separator may be a single member, and may be located between the positive and negative electrodes, or may be attached to the surface of the positive and negative electrodes.

[0123] In some embodiments, the separator is a solid electrolyte that is disposed between the positive and negative electrodes and serves to transmit ions and separate the positive and negative electrodes.

[0124] In some embodiments, the battery cell 10 further includes an electrolyte, which serves to conduct ions between the positive and negative electrodes. The present application is not specifically limited to the type of electrolyte, which can be selected according to needs. The electrolyte may be liquid, gel, or solid.

[0125] Here, the liquid electrolyte contains an electrolyte salt and a solvent.

[0126] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonate), lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0127] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone. The solvent is optionally an ether-based solvent. The ether-based solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0128] Here, the gel electrolyte comprises a polymer-electrolyte skeletal network combined with an ionic liquid-lithium salt.

[0129] Here, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0130] By way of example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethylmethacrylate, monoionic polymers, polyionic liquid-lithium salts, cellulose, and the like.

[0131] By way of example, the inorganic solid electrolyte may be one or more of oxide solid electrolytes (crystalline perovskites, sodium superionic conductors, garnets, amorphous LiPON films), sulfide solid electrolytes (crystalline lithium superionic conductors (lithium germanium phosphorus sulfur, argillite), amorphous sulfides), and halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0132] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0133] In some embodiments, the electrode assembly 2 is a wound structure. The positive and negative plates are wound into the wound structure.

[0134] In some embodiments, the electrode assembly 2 is a laminate structure.

[0135] For example, a plurality of positive electrode plates and a plurality of negative electrode plates may be provided, and the plurality of positive electrode plates and the plurality of negative electrode plates are provided in an alternating stack.

[0136] As an example, the positive plates may be arranged in a plurality of layers, and the negative plates may be folded to form a plurality of folded segments arranged in a stack, with one positive plate sandwiched between adjacent folded segments.

[0137] By way of example, both the positive and negative plates may be folded to form a number of folded segments that are arranged in a stack.

[0138] For example, a plurality of separators may be provided, each of which may be provided between adjacent positive or negative electrode plates.

[0139] As an example, the separator may be disposed continuously or may be disposed between adjacent positive or negative plates in a folded or wound manner.

[0140] In some embodiments, the shape of the electrode assembly 2 may be cylindrical, flat, polygonal prism, or the like.

[0141] In some embodiments, the electrode assembly 2 is provided with tabs that allow electrical current to be conducted away from the electrode assembly 2. The tabs include a positive tab 21 and a negative tab 22.

[0142] The battery cell 10 may further include an electrode terminal, which may be installed in the housing 1 and used to be electrically connected to a tab of the electrode assembly 2 so as to output the electric energy of the battery cell 10. The electrode terminal and the tab may be directly connected, for example, the electrode terminal and the tab are directly welded. The electrode terminal and the tab may be indirectly connected, for example, the electrode terminal and the tab are indirectly connected through a current collecting part. The current collecting part may be a metal conductor, for example, copper, iron, aluminum, steel, aluminum alloy, etc.

[0143] As shown in FIG. 3, for example, the case 12 is a hollow structure with an opening at one end. Two electrode terminals may be installed on the end cap 11, which are a positive electrode terminal 3 and a negative electrode terminal 4, respectively. The positive electrode terminal 3 is electrically connected to the positive tab 21, and the negative electrode terminal 4 is electrically connected to the negative tab 22.

[0144] 4 to 7, FIG. 4 is a structural schematic diagram of a housing member 5 according to some embodiments of the present application, FIG. 5 is a cross-sectional view of the housing member 5 shown in FIG. 4 along the line CC, FIG. 6 is a grain diagram (schematic diagram) of the housing member 5 shown in FIG. 5, and FIG. 7 is a local enlarged view of a portion E of the housing member 5 shown in FIG. 5. An embodiment of the present application provides a housing member 5 for a battery cell 10, which includes a non-weakened region 51 and a weak region 52 integrally formed, a groove portion 53 is provided in the housing member 5, the non-weakened region 51 is formed around the groove portion 53, and the weak region 52 is formed at the bottom of the groove portion 53, and the weak region 52 is configured to be broken when the battery cell 10 releases internal pressure. Here, the average grain size of the weak region 52 is S1, and the average grain size of the non-weakened region 51 is S2, satisfying S1 / S2≦0.9.

[0145] The housing member 5 is a member capable of housing the electrode assembly 2 in cooperation with other members and is a part of the housing 1, and the end caps 11 of the housing 1 may be the housing members 5, and the case 12 of the housing 1 may be the housing member 5. The housing member 5 may be made of a metal material, such as copper, iron, aluminum, steel, aluminum alloy, etc., or may be an aluminum plastic film.

[0146] The weak area 52 is a part weaker than other areas of the housing member 5, and when the internal pressure of the battery cell 10 reaches a threshold, the weak area 52 of the housing member 5 can be broken to release the pressure inside the battery cell 10. The weak area 52 can be broken by bursting, detachment, or other methods. For example, when the internal pressure of the battery cell 10 reaches a threshold, the weak area 52 bursts under the action of the exhaust (gas, electrolyte, etc.) inside the battery cell 10, thereby allowing the exhaust inside the battery cell 10 to be smoothly discharged. The weak area 52 may have various shapes, for example, a rectangular shape, a circular shape, an elliptical shape, an annular shape, an arc shape, a U shape, an H shape, etc. The thickness of the weak area 52 may be uniform or non-uniform.

[0147] The fragile region 52 is formed at the bottom of the groove portion 53, and the groove portion 53 may be formed by various methods to realize integral molding of the fragile region 52 and the non-fragile region 51, for example, by a molding method such as pressing, milling, laser etching, etc. After the groove portion 53 is press-molded in the housing member 5, the region of the housing member 5 where the groove portion 53 is installed is thinned to form the fragile region 52. The groove portion 53 may be a one-stage groove, and the groove side surface of the groove portion 53 is continuous along the depth direction of the groove portion 53, for example, the groove portion 53 is a groove whose internal space is a rectangular parallelepiped, columnar, or the like. The groove portion 53 may be a multi-stage groove, and the multi-stage grooves are arranged along the depth direction of the groove portion 53, and of two adjacent stages of grooves, the one stage groove on the inside (deep position) is installed on the groove bottom surface of the one stage groove on the outside (shallow position), for example, the groove portion 53 is a stepped groove. During molding, the multi-stage grooves can be press-molded one stage at a time along the depth direction of the groove portion 53, and the weak area 52 is formed at the bottom of one stage of the groove that is located at the deepest position (innermost) among the multi-stage grooves.

[0148] The non-weakened region 51 is formed around the groove portion 53, and the strength of the non-weakened region 51 is greater than the strength of the weak region 52, and the weak region 52 is more easily broken than the non-weakened region 51. When the groove portion 53 is formed in the housing member 5 by a pressing method, the non-weakened region 51 may be a portion of the housing member 5 that is not pressed. The thickness of the non-weakened region 51 may be uniform or non-uniform.

[0149] The method for measuring the average grain size can be referred to the cutting method in GB 6394-2017, and will not be described further here. When measuring the average grain size of the weak region 52, it can be measured along the thickness direction of the weak region 52, and when measuring the average grain size of the non-weakened region 51, it can be measured along the thickness direction of the non-weakened region 51.

[0150] In FIG. 5, the thickness direction of the weakened region 52 and the thickness direction of the non-weakened region 51 coincide with each other and are both in the Z direction.

[0151] S1 / S2 may be any one of the following values ​​or a range between any two of: 0.01, 0.03, 0.04, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9.

[0152] In the embodiment of the present application, the weak region 52 and the non-weakened region 51 are integrally molded, so that the reliability of the housing member 5 is higher. Since S1 / S2≦0.9, the difference between the average grain size of the weak region 52 and the average grain size of the non-weakened region 51 is large, so that the average grain size of the weak region 52 is reduced, and the purpose of fine graining of the weak region 52 is achieved, so that the mechanical performance of the material of the weak region 52 is improved, and the toughness and fatigue resistance strength of the weak region 52 are improved, so that the risk of the weak region 52 being broken under normal use conditions of the battery cell 10 is reduced, and the service life of the battery cell 10 is extended.

[0153] In some embodiments, S1 / S2 > 0.05.

[0154] The inventor discovered that when S1 / S2<0.05, it becomes difficult to form the weak area 52, and the strength of the weak area 52 is too great, so that it becomes difficult for the weak area 52 to be destroyed in the event of thermal runaway of the battery cell 10, and it is easy for pressure to be released in a timely manner.

[0155] Therefore, S1 / S2≧0.05, which reduces the difficulty of forming the weak area 52 and improves the instantaneous pressure release during thermal runaway of the battery cell 10.

[0156] In some embodiments, 0.1≦S1 / S2≦0.5.

[0157] S1 / S2 may be any one of the following values ​​or a range between any two of: 0.1, 0.12, 0.15, 0.17, 0.2, 0.22, 0.25, 0.27, 0.3, 0.32, 0.35, 0.37, 0.4, 0.42, 0.45, 0.47, 0.5.

[0158] In this embodiment, 0.1≦S1 / S2≦0.5, which ensures that the overall performance of the housing member 5 is better and that the weak area 52 can be destroyed in a timely manner when the battery cell 10 experiences thermal runaway, while also ensuring that the weak area 52 has sufficient strength under normal usage conditions of the battery cell 10.

[0159] In some embodiments, 0.4 μm≦S1≦75 μm.

[0160] S1 may be any one of the following values ​​or a range between any two of: 0.4 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 28 μm, 30 μm, 35 μm, 36 μm, 40 μm, 45 μm, 49 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 72 μm, 75 μm.

[0161] The inventors discovered that when S1>75 μm, the toughness and fatigue resistance strength of the weak area 52 are poor, and when S1<0.4 mm, it is difficult to form the weak area 52 and the strength of the weak area 52 is too high, making it more likely that the weak area 52 will be destroyed in the event of thermal runaway of the battery cell 10, and making it easy for pressure to be released in a timely manner.

[0162] Therefore, 0.1 μm≦S1≦75 μm is satisfied, which reduces the difficulty of forming the weak region 52, improves the immediacy of pressure release during thermal runaway of the battery cell 10, and improves the toughness and fatigue resistance strength of the weak region 52, thereby reducing the risk of the weak region 52 being destroyed under normal usage conditions of the battery cell 10.

[0163] In some embodiments, 1 μm≦S1≦10 μm.

[0164] S1 may be any one of the following values ​​or a range between any two of 1 μm, 1.5 μm, 1.6 μm, 2 μm, 2.5 μm, 2.6 μm, 3 μm, 3.5 μm, 3.6 μm, 4 μm, 4.5 μm, 4.6 μm, 5 μm, 5.5 μm, 5.6 μm, 6 μm, 6.5 μm, 6.6 μm, 7 μm, 7.5 μm, 7.6 μm, 8 μm, 8.5 μm, 8.6 μm, 9 μm, 9.5 μm, 9.6 μm, and 10 μm.

[0165] In this embodiment, 1 μm≦S1≦10 μm, which ensures that the overall performance of the housing member 5 is better and that the weak area 52 can be destroyed in a timely manner when the battery cell 10 experiences thermal runaway, while also ensuring that the weak area 52 has sufficient strength under normal usage conditions of the battery cell 10.

[0166] In some embodiments, 10 μm≦S2≦150 μm.

[0167] S2 may be any one of the following values ​​or a range between any two of 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm.

[0168] In some embodiments, 30 μm≦S2≦100 μm.

[0169] S2 may be any one of the following values ​​or a range between any two of: 30 μm, 32 μm, 35 μm, 37 μm, 40 μm, 42 μm, 45 μm, 47 μm, 50 μm, 52 μm, 55 μm, 57 μm, 60 μm, 62 μm, 65 μm, 67 μm, 70 μm, 72 μm, 75 μm, 77 μm, 80 μm, 82 μm, 85 μm, 87 μm, 90 μm, 92 μm, 95 μm, 97 μm, 100 μm.

[0170] In some embodiments, the minimum thickness of weakened region 52 satisfies 1≦A / S1≦100.

[0171] A / S1 may be any one of the following values ​​or a range between any two of: 1, 2, 4, 5, 10, 15, 20, 21, 22, 23, 25, 30, 33, 34, 35, 37, 38, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 93, 94, 95, 100.

[0172] When A / S1<1, the number of crystal grain layers in the thickness direction of the weak region 52 is small, and the fatigue resistance strength of the weak region 52 is too small. On the other hand, when A / S1>100, the number of crystal grain layers in the thickness direction of the weak region 52 is too large, and the strength of the weak region 52 is too high, which increases the risk that the weak region 52 will not be destroyed in a timely manner in the event of thermal runaway of the battery cell 10.

[0173] Therefore, 1≦A / S1≦100, the number of crystal grain layers in the thickness direction of the weak region 52 is large, which improves the fatigue resistance strength of the weak region 52 and reduces the risk that the weak region 52 will be destroyed under normal usage conditions of the battery cell 10. In addition, the weak region 52 can be destroyed in a more timely manner when the battery cell 10 experiences thermal runaway, thereby achieving the purpose of timely pressure relief.

[0174] In some embodiments, 5≦A / S1≦20.

[0175] A / S1 may be any one of the values ​​5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20 or a range between any two of these values.

[0176] In this embodiment, 5≦A / S1≦20, which ensures that the overall performance of the housing member 5 is better and that the weak area 52 can be destroyed in a timely manner when the battery cell 10 experiences thermal runaway, and also ensures that the weak area 52 has sufficient fatigue resistance strength under normal usage conditions of the battery cell 10, thereby extending the service life of the battery cell 10.

[0177] In some embodiments, the minimum thickness of the weakened region 52 is A and the hardness of the weakened region 52 is H1, where 5 HBW / mm≦H1 / A≦10,000 HBW / mm.

[0178] H1 / A may be any one of the following values ​​or a range between any two of: 5HBW / mm, 6HBW / mm, 7HBW / mm, 20HBW / mm, 50HBW / mm, 61HBW / mm, 62HBW / mm, 63HBW / mm, 64HBW / mm, 75HBW / mm, 90HBW / mm, 100HBW / mm, 120HBW / mm, 150HBW / mm, 190HBW / mm, 500HBW / mm, 1000HBW / mm, 1200HBW / mm, 1750HBW / mm, 1800HBW / mm, 2100HBW / mm, 4000HBW / mm, 5000HBW / mm, 8000HBW / mm, 9000HBW / mm, and 10000HBW / mm.

[0179] The hardness of the weak area 52 is the Brinell hardness in HBW units. The measurement method of the Brinell hardness can be carried out by referring to the measurement principle in GB / T 23.1-2018. In the actual measurement process, the hardness of the weak area 52 can be measured on the inner surface or outer surface in the thickness direction of the weak area 52. Take the housing member 5 as an end cap 11 of the battery cell 10 as an example, the hardness of the weak area 52 can be measured on the outer surface opposite to the inner side of the battery cell 10, or the hardness of the weak area 52 can be measured on the inner surface facing the inner side of the battery cell 10.

[0180] When H1 / A>10,000 HBW / mm, the weak area 52 is thin and has a high hardness, so that it is very thin and brittle and is easily broken under normal use conditions of the battery cell 10, and the service life of the battery cell 10 is short. When H1 / A<5 HBW / mm, the weak area 52 is thick and has a low hardness, so that it is stretched when the battery cell 10 experiences thermal runaway, and the immediate release of pressure is poor.

[0181] In this embodiment, the effect of the thickness of the weak area 52 on the performance of the housing member 5 is taken into consideration, and the effect of the hardness of the weak area 52 on the performance of the housing member 5 is also taken into consideration, so that 5HBW / mm≦H1 / A≦10,000HBW / mm is satisfied, so that the weak area 52 can have sufficient strength under normal usage conditions of the battery cell 10, the weak area 52 is less likely to be destroyed by fatigue, the service life of the battery cell 10 is extended, and the housing member 5 can timely release pressure through the weak area 52 when the battery cell 10 experiences thermal runaway, thereby reducing the risk of the battery cell 10 exploding and improving the safety of the battery cell 10.

[0182] In some embodiments, 190 HBW / mm≦H1 / A≦4000 HBW / mm.

[0183] H1 / A may be any one of the following values ​​or a range between any two of 190HBW / mm, 250HBW / mm, 280HBW / mm, 300HBW / mm, 350HBW / mm, 400HBW / mm, 450HBW / mm, 500HBW / mm, 600HBW / mm, 700HBW / mm, 875HBW / mm, 1000HBW / mm, 1200HBW / mm, 1500HBW / mm, 1750HBW / mm, 1800HBW / mm, 2000HBW / mm, 2100HBW / mm, 2500HBW / mm, 3000HBW / mm, 3500HBW / mm, and 4000HBW / mm.

[0184] In this embodiment, 190HBW / mm≦H1 / A≦4000HBW / mm, which ensures that the overall performance of the housing member 5 is better, ensures that the weak area 52 can be broken in a timely manner when the battery cell 10 experiences thermal runaway, and ensures that the weak area 52 has sufficient strength under normal conditions of use of the battery cell 10. While ensuring the safety of the battery cell 10, the service life of the battery cell 10 is extended.

[0185] In some embodiments, 0.02 mm≦A≦1.6 mm.

[0186] A may be any one of the following values ​​or a range between any two of: 0.02 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.42 mm, 1.43 mm, 1.45 mm, 1.47 mm, 1.5 mm, 1.55 mm, and 1.6 mm.

[0187] If A<0.02 mm, it is difficult to form the weak area 52 and the weak area 52 is likely to be damaged during the forming process. On the other hand, if A>1.6 mm, it is more difficult for the weak area 52 to be destroyed in the event of thermal runaway of the battery cell 10, and it is more likely that pressure will not be released in a timely manner.

[0188] Therefore, 0.02 mm≦A≦1.6 mm is satisfied, which reduces the difficulty of forming the pressure relief area 56 and improves the immediate pressure relief when the battery cell 10 experiences thermal runaway.

[0189] In some embodiments, 0.06 mm≦A≦0.4 mm.

[0190] A may be any one of the following values ​​or a range between any two of 0.06 mm, 0.07 mm, 0.08 mm, 0.1 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, and 0.4 mm.

[0191] In this embodiment, 0.06 mm≦A≦0.4 mm, which further reduces the difficulty of forming the weakened area 52 and improves the instantaneous pressure release in the event of thermal runaway of the battery cell 10.

[0192] In some embodiments, the hardness of the weakened region 52 is H1 and the hardness of the non-weakened region 51 is H2, where H1>H2.

[0193] The hardness of the non-weakened area 51 is a Brinell hardness in units of HBW. In an actual measurement process, the hardness of the non-weakened area 51 can be measured on the inner surface or outer surface in the thickness direction of the non-weakened area 51. For example, if the housing member 5 is the end cap 11 of the battery cell 10, the hardness of the non-weakened area 51 can be measured on the outer surface of the non-weakened area 51 opposite to the inside of the battery cell 10, or the hardness of the non-weakened area 51 can be measured on the inner surface of the non-weakened area 51 facing the inside of the battery cell 10.

[0194] In this embodiment, H1>H2, which corresponds to increasing the hardness of the weak area 52, thereby improving the strength of the weak area 52 and reducing the risk that the weak area 52 will be destroyed under normal usage conditions of the battery cell 10.

[0195] In some embodiments, H1 / H2≦5.

[0196] H1 / H2 may be any one of the following values: 1.1, 1.5, 2, 2.5, 3, 3.5, 3.6, 4, 4.5, 5 or a range value between any two of these values.

[0197] If H1 / H2>5, the hardness of the weakened area 52 may be too large, and a situation may arise in which the weakened area 52 is very difficult to destroy during thermal runaway of the battery cell 10.

[0198] Therefore, H1 / H2≦5, which reduces the risk that the vulnerable area 52 cannot be destroyed in a timely manner when the battery cell 10 experiences thermal runaway, thereby improving the safety of the battery cell 10.

[0199] In some embodiments, H1 / H2≦2.5.

[0200] H1 / H2 may be any one of the following values ​​or a range between any two of 1.1, 1.11, 1.12, 1.2, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.71, 1.72, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5.

[0201] In this embodiment, H1 / H2≦2.5, and the risk that the vulnerable region 52 cannot be destroyed in a timely manner when the battery cell 10 experiences thermal runaway can be further reduced.

[0202] In some embodiments, 5HBW≦H2≦150HBW.

[0203] H2 may be any one of the following values ​​or a range between any two of: 5HBW, 8HBW, 9HBW, 9.5HBW, 10HBW, 15HBW, 16HBW, 19HBW, 20HBW, 30HBW, 40HBW, 50HBW, 52HBW, 52.5HBW, 53HBW, 60HBW, 70HBW, 80HBW, 90HBW, 100HBW, 110HBW, 120HBW, 130HBW, 140HBW, 150HBW.

[0204] In some embodiments, 5HBW≦H1≦200HBW.

[0205] H1 may be any one of the values ​​of 5HBW, 6HBW, 8HBW, 10HBW, 15HBW, 19HBW, 20HBW, 30HBW, 50HBW, 60HBW, 70HBW, 80HBW, 90HBW, 100HBW, 110HBW, 120HBW, 130HBW, 140HBW, 150HBW, 160HBW, 170HBW, 180HBW, 190HBW, 200HBW, or a range value between any two of these.

[0206] 7 and 8, in some embodiments, Fig. 8 is a localized enlarged view of a housing member 5 according to some other embodiments of the present application. The minimum thickness of the weakened region 52 is A, and the minimum thickness of the non-weakened region 51 is B, satisfying 0.05≦A / B≦0.95.

[0207] The minimum thickness of the weakened region 52 is the thickness of the weakened region 52 at its thinnest point. The minimum thickness of the non-weakened region 51 is the thickness of the non-weakened region 51 at its thinnest point.

[0208] As shown in Figures 7 and 8, the housing member 5 has a first surface 54 and a second surface 55 arranged opposite each other, the groove portion 53 is recessed in a direction from the first surface 54 toward the second surface 55, and the portion located between the groove bottom surface 531 of the groove portion of the housing member 5 and the second surface 55 is the weak area 52.

[0209] The first surface 54 and the second surface 55 may be arranged parallel to each other or arranged at a small angle. When the first surface 54 and the second surface 55 are arranged at a small angle, for example, the angle between them is 10 degrees or less, the minimum distance between the first surface 54 and the second surface 55 is the minimum thickness of the non-weakened region 51. When the first surface 54 and the second surface 55 are parallel to each other, as shown in Figures 7 and 8, the distance between the first surface 54 and the second surface 55 is the minimum thickness of the non-weakened region 51.

[0210] The groove bottom surface 531 of the groove portion may be a plane or a curved surface. When the groove bottom surface 531 of the groove portion is a plane, the groove bottom surface 531 of the groove portion and the second surface 55 may be arranged parallel to each other or at a small angle. When the groove bottom surface 531 of the groove portion and the second surface 55 are arranged at a small angle, for example, the angle between them is 10 degrees or less, the minimum distance between the groove bottom surface 531 of the groove portion and the second surface 55 is the minimum thickness of the weakened region 52. When the groove bottom surface 531 of the groove portion and the second surface 55 are parallel to each other, as shown in FIG. 7, the distance between the groove bottom surface 531 of the groove portion and the second surface 55 is the minimum thickness of the weakened region 52. When the groove bottom surface 531 of the groove portion is a curved surface, for example, the groove bottom surface 531 of the groove portion is an arc surface, as shown in FIG. 8, the minimum distance between the groove bottom surface 531 of the groove portion and the second surface 55 is the minimum thickness of the weakened region 52.

[0211] A / B may be any one of the following values ​​or a range between any two of: 0.05, 0.06, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.8, 0.85, 0.9, 0.95.

[0212] When A / B<0.05, the strength of the weak region 52 may be insufficient, increasing the probability that the weak region 52 will explode under normal use conditions of the battery cell 10. When A / B>0.95, the weak region 52 may be difficult to destroy when the battery cell 10 experiences thermal runaway, increasing the probability that the battery cell 10 will explode due to insufficient pressure release. Therefore, when 0.05≦A / B≦0.95, the probability that the weak region 52 will explode under normal use conditions of the battery cell 10 can be reduced, and the probability that the battery cell 10 will explode when the battery cell 10 experiences thermal runaway can be reduced.

[0213] In some embodiments, 0.12≦A / B≦0.8.

[0214] A / B may be any one of the following values ​​or a range between any two of 0.12, 0.13, 0.14, 0.15, 0.17, 0.2, 0.22, 0.25, 0.27, 0.3, 0.32, 0.35, 0.37, 0.4, 0.42, 0.45, 0.47, 0.5, 0.52, 0.55, 0.57, 0.6, 0.62, 0.65, 0.66, 0.67, 0.7, 0.72, 0.75, 0.77, 0.8.

[0215] In this embodiment, 0.12≦A / B≦0.8, which ensures that the overall performance of the housing members is superior and that the weak region 52 can be broken in a timely manner when the battery cell 10 experiences thermal runaway, while also ensuring that the weak region 52 has sufficient strength under normal usage conditions of the battery cell 10. When the groove portion 53 is formed by the pressing method, by controlling A / B to be between 0.12 and 0.8, it is possible to easily make S1 / S2 ≦0.5, thereby achieving the purpose of finely refining the crystal grains of the weak region 52.

[0216] In some embodiments, 0.2≦A / B≦0.5.

[0217] A / B may be any one of the following values ​​or a range between any two of: 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5.

[0218] In this embodiment, by controlling A / B to be between 0.2 and 0.5, the risk of the weak area 52 being destroyed under normal usage conditions of the battery cell 10 is further reduced, and the weak area 52 is ensured to be destroyed in a timely manner when the battery cell 10 experiences thermal runaway, thereby improving the immediacy of pressure release.

[0219] In some embodiments, 0.02 mm≦A≦1.6 mm.

[0220] Furthermore, 0.06 mm≦A≦0.4 mm.

[0221] In some embodiments, 1 mm≦B≦5 mm.

[0222] B may be any one of the following values: 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or a range between any two of these values.

[0223] When B>5 mm, the thickness of the non-weakened region 51 is large, the amount of material of the housing member 5 is large, the mass of the housing member 5 is large, and this is not economical. When B<1 mm, the thickness of the non-weakened region 51 is small, and the deformation resistance of the housing member 5 is poor.

[0224] Therefore, when 1 mm≦B≦5 mm, the housing member 5 has good economic efficiency and good deformation resistance.

[0225] Furthermore, 1.2 mm≦B≦3.5 mm.

[0226] B may be any one of the following values ​​or a range between any two of 1.2mm, 1.25mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm.

[0227] In this embodiment, 1.2 mm≦B≦3.5 mm, and the housing member 5 has better economy and deformation resistance.

[0228] Furthermore, 2 mm≦B≦3 mm.

[0229] In some embodiments, referring to Figures 9-14, Figure 9 is a structural schematic diagram of a housing member 5 according to yet another embodiment of the present application (showing a one-step groove 532), Figure 10 is an E-E cross-sectional view of the housing member 5 shown in Figure 9, Figure 11 is a structural schematic diagram of a housing member 5 according to further embodiments of the present application (showing a one-step groove 532), Figure 12 is an F-F cross-sectional view of the housing member 5 shown in Figure 11, Figure 13 is a structural schematic diagram of a housing member 5 according to another embodiment of the present application (showing a one-step groove 532), and Figure 14 is a G-G cross-sectional view of the housing member 5 shown in Figure 13. The housing member 5 has a pressure relief area 56, the groove portion 53 includes a one-stage notched groove 532, the notched groove 532 is located along the edge of the pressure relief area 56, the pressure relief area 56 is configured to be openable using the notched groove 532 as a boundary, and the weakened area 52 forms the bottom of the notched groove 532.

[0230] The pressure relief area 56 is an area of ​​the housing member 5 that can be opened after the weakened area 52 is broken. For example, when the internal pressure of the battery cell 10 reaches a threshold, the weakened area 52 is torn, and the pressure relief area 56 is opened outward under the action of the waste inside the battery cell 10. In this process, the weakened area 52 is torn along the notched groove 532, and the pressure relief area 56 is opened, thereby realizing that the pressure relief area 56 is opened with the notched groove 532 as a boundary. After the pressure relief area 56 is opened, the housing member 5 can form an exhaust port at a position corresponding to the pressure relief area 56, and the waste inside the battery cell 10 can be exhausted through the exhaust port to relieve the pressure inside the battery cell 10.

[0231] The notched groove 532 can be formed in the housing member 5 by various methods, such as press molding, milling molding, laser etching molding, etc. The notched groove 532 in the groove portion 53 has only one stage, and the notched groove 532 of one stage can be formed by one press. The notched groove 532 may be a groove of various shapes, such as an annular groove, an arc-shaped groove, a U-shaped groove, an H-shaped groove, etc. The weakened region 52 is formed at the bottom of the notched groove 532, and the shape of the weakened region 52 and the shape of the notched groove 532 are the same. For example, when the weakened region 52 is a U-shaped groove, the weakened region 52 extends along a U-shaped locus.

[0232] As an example, the maximum width of the notched groove 532 is X, where X≦10 mm. The width of the notched groove 532 at its deepest position is the maximum width of the notched groove 532.

[0233] In this embodiment, the weakened area 52 forms the bottom of the notched groove 532, and when the weakened area 52 is broken, the pressure relief area 56 can open with the weakened area 52 as a boundary, thereby realizing pressure relief and increasing the pressure relief area of ​​the housing member 5.

[0234] In some embodiments, with continued reference to Figures 10, 12 and 14, the housing member 5 has a first surface 54 and a second surface 55 disposed opposite each other, and the notched groove 532 is recessed in a direction from the first surface 54 toward the second surface 55.

[0235] The first surface 54 may be an inner surface of the housing member 5 facing the inside of the battery cells 10, and the second surface 55 may be an outer surface of the housing member 5 opposite the inside of the battery cells 10, or the first surface 54 may be an outer surface of the housing member 5 opposite the inside of the battery cells 10, and the second surface 55 may be an inner surface of the housing member 5 facing the inside of the battery cells 10. As an example, the first surface 54 is parallel to the second surface 55, and the minimum thickness of the non-weakened region 51 is the distance between the first surface 54 and the second surface 55.

[0236] The groove bottom surface of the notched groove 532 is the groove bottom surface 531 of the groove portion. The portion between the groove bottom surface of the notched groove 532 and the second surface 55 of the housing member 5 is the groove bottom wall of the notched groove 532, and the groove bottom wall of the notched groove 532 is the weakened region 52.

[0237] In this embodiment, the groove portion 53 only includes one-stage notched groove 532, and the notched groove 532 is the groove portion 53, and the groove portion 53 is a one-stage groove, so that the structure is simple. During molding, the notched groove 532 can be molded on the first surface 54, so that the molding is simple, the production efficiency is improved, and the production cost is reduced.

[0238] In some embodiments, referring to Figures 15-20, Figure 15 is a structural schematic diagram of a housing member 5 according to yet another embodiment of the present application (showing a two-stage groove 532), Figure 16 is a KK cross-sectional view of the housing member 5 shown in Figure 15, Figure 17 is a structural schematic diagram of a housing member 5 according to further embodiments of the present application (showing a two-stage groove 532), Figure 18 is an MM cross-sectional view of the housing member 5 shown in Figure 17, Figure 19 is a structural schematic diagram of a housing member 5 according to another embodiment of the present application (showing a two-stage groove 532), and Figure 20 is an NN cross-sectional view of the housing member 5 shown in Figure 19. The housing member 5 includes a first surface 54 and a second surface 55 disposed opposite to each other, and the groove portion 53 includes a multi-stage notched groove 532, which are disposed in sequence on the housing member 5 along a direction from the first surface 54 to the second surface 55, and the weakened area 52 is formed at the bottom of the notched groove 532 of a stage farthest from the first surface 54. Here, the housing member 5 has a pressure relief area 56, and the notched grooves 532 of each stage are disposed along an edge of the pressure relief area 56, and the pressure relief area 56 is configured to be able to open with the notched groove 532 of a stage farthest from the first surface 54 as a boundary.

[0239] The groove portion 53 includes a multi-stage notched groove 532, and it can be understood that the groove portion 53 is a multi-stage groove. The notched grooves 532 of each stage are arranged along the edge of the pressure relief area 56, and it can be understood that the extension direction of the multi-stage notched grooves 532 is basically the same, and the shape of the multi-stage notched grooves 532 is basically the same, so that the multi-stage notched grooves 532 are all arranged to surround the pressure relief area 56. The notched grooves 532 in the groove portion 53 may be two stages, three stages, four stages or more. The notched grooves 532 of each stage may be formed on the housing member 5 by a press molding method. During molding, the notched grooves 532 of each stage can be press molded in order along the direction from the first surface 54 to the second surface 55. When the multi-stage notched grooves 532 are press molded, the multi-stage notched grooves 532 can be formed by multiple presses, and each press molds one stage of the notched groove 532. The notched grooves 532 may be grooves of various shapes, such as annular grooves, arc-shaped grooves, U-shaped grooves, H-shaped grooves, and the like.

[0240] The pressure relief area 56 is an area of ​​the housing member 5 that can be opened after the weakened area 52 is broken. The one-stage groove 532 furthest from the first surface 54 is located at the edge of the pressure relief area 56, and in the process of opening the pressure relief area 56, the weakened area 52 tears along the one-stage groove 532 furthest from the first surface 54, thereby realizing that the pressure relief area 56 opens with the one-stage groove 532 furthest from the first surface 54 as a boundary.

[0241] The weak region 52 is formed at the bottom of the one-step notched groove 532 farthest from the first surface 54, and the one-step notched groove 532 farthest from the first surface 54 is the one-step notched groove 532 at the deepest position (innermost). Of the two adjacent notched grooves 532, the one-step notched groove 532 farthest from the first surface 54 is disposed on the bottom surface of the one-step notched groove 532 closer to the first surface 54. The portion of the housing member 5 between the groove bottom surface of the one-step notched groove 532 farthest from the first surface 54 and the second surface 55 is the groove bottom wall of the one-step notched groove 532 farthest from the first surface 54, and this groove bottom wall is the weak region 52. The groove bottom surface of the one-step notched groove 532 farthest from the first surface 54 is the groove bottom surface 531 of the groove portion. The single-step groove 532 furthest from the first surface 54 is the innermost single-step groove 532b, and the single-step groove 532 closest to the first surface 54 is the outermost single-step groove 532a.

[0242] For example, the maximum width of the outermost one-step notched groove 532a is X, where X≦10 mm. The width of the outermost one-step notched groove 532a at its deepest position is the maximum width of the outermost one-step notched groove 532a.

[0243] During molding, multi-stage notched grooves 532 can be molded in the housing member 5, one stage at a time, and the molding depth of each stage of notched grooves 532 can be reduced, thereby reducing the molding force that the housing member 5 receives when molding each stage of notched grooves 532, reducing the risk of cracks occurring in the housing member 5, and the housing member 5 is less likely to break down due to cracks occurring at the positions where the notched grooves 532 are installed, thereby extending the service life of the housing member 5.

[0244] In some embodiments, referring to FIGS. 16, 18 and 20, the step of groove 532 furthest from second surface 55 is recessed in a direction from first surface 54 toward second surface 55.

[0245] For example, if the notched groove 532 in the groove portion 53 has two stages, the two stages of the notched groove 532 are the first stage notched groove and the second stage notched groove. The first stage notched groove is disposed on the first surface 54, i.e., recessed from the first surface 54 in a direction closer to the second surface 55, and the second stage notched groove is disposed on the groove bottom surface of the first stage notched groove, i.e., recessed from the groove bottom surface of the first stage notched groove in a direction closer to the second surface 55. The first stage notched groove is the outermost one-stage notched groove 532a, and the second stage notched groove is the innermost one-stage notched groove 532b.

[0246] The groove portion 53 is composed of multi-stage notched grooves 532, and during molding, the multi-stage notched grooves 532 can be gradually processed in the direction from the first surface 54 to the second surface 55, resulting in high molding efficiency.

[0247] In some embodiments, referring to Figures 21-27, Figure 21 is an oblique view of a housing member 5 according to some embodiments of the present application, Figure 22 is a structural schematic diagram of the housing member 5 shown in Figure 21 (showing a one-step notched groove 532 and a one-step countersunk groove 533), Figure 23 is an OO cross-sectional view of the housing member 5 shown in Figure 22, Figure 24 is a structural schematic diagram of a housing member 5 according to further some embodiments of the present application (showing a one-step notched groove 532 and a one-step countersunk groove 533), Figure 25 is a PP cross-sectional view of the housing member 5 shown in Figure 24, Figure 26 is a structural schematic diagram of a housing member 5 according to another some embodiments of the present application (showing a one-step notched groove 532 and a one-step countersunk groove 533), and Figure 27 is a QQ cross-sectional view of the housing member 5 shown in Figure 26. The housing member 5 includes a first surface 54 and a second surface 55 arranged opposite each other, and the groove portion 53 further includes a one-stage countersunk groove 533, which is recessed from the first surface 54 in a direction closer to the second surface 55, and the pressure relief area 56 is formed in a groove bottom wall 5331 of the countersunk groove.

[0248] It should be explained that, of course, regardless of whether the notched groove 532 in the groove portion 53 is one-stage or multi-stage, the groove portion 53 may include a one-stage countersunk groove 533. As can be understood, the groove portion 53 also has the notched groove 532 and the countersunk groove 533, and the groove portion 53 is a multi-stage groove. The countersunk groove 533 and the notched groove 532 are arranged along a direction from the first surface 54 to the second surface 55. During molding, the countersunk groove 533 can be molded in the housing member 5, and the notched groove 532 can be molded in the groove bottom wall 5331 of the countersunk groove. The countersunk groove 533 can be molded in the housing member 5 in various ways, such as press molding, milling molding, laser etching molding, etc.

[0249] The groove bottom wall 5331 of the countersunk groove is a portion of the housing member 5 below the groove bottom surface of the countersunk groove 533, and after the countersunk groove 533 is formed in the first surface 54, the remaining portion of the housing member 5 in the region where the countersunk groove 533 is provided is the groove bottom wall 5331 of the countersunk groove. As shown in Figures 23, 25, and 27, the portion of the housing member 5 between the groove bottom surface of the countersunk groove 533 and the second surface 55 is the groove bottom wall 5331 of the countersunk groove. Here, the pressure relief region 56 may be a portion of the groove bottom wall 5331 of the countersunk groove.

[0250] By providing the countersunk groove 533, the depth of the notched groove 532 can be reduced while ensuring a constant thickness of the final weakened region 52, thereby reducing the molding force that the housing member 5 receives when molding the notched groove 532, and reducing the risk of cracks occurring in the housing member 5. In addition, the countersunk groove 533 can provide an escape space in the process of opening to the pressure relief region 56, so that even if the first surface 54 is blocked by an obstacle, the pressure relief region 56 can still open to relieve pressure.

[0251] In some embodiments, referring to Figures 28-33, Figure 28 is a structural schematic diagram of a housing member 5 according to some embodiments of the present application (showing a one-stage notched groove 532 and a two-stage countersunk groove 533), Figure 29 is an RR cross-sectional view of the housing member 5 shown in Figure 28, Figure 30 is a structural schematic diagram of a housing member 5 according to further some embodiments of the present application (showing a one-stage notched groove 532 and a two-stage countersunk groove 533), Figure 31 is an SS cross-sectional view of the housing member 5 shown in Figure 30, Figure 32 is a structural schematic diagram of a housing member 5 according to another some embodiments of the present application (showing a one-stage notched groove 532 and a two-stage countersunk groove 533), and Figure 33 is a TT cross-sectional view of the housing member 5 shown in Figure 32. The housing member 5 includes a first surface 54 and a second surface 55 arranged opposite each other, and the groove portion 53 further includes a multi-stage countersunk groove 533, which are arranged in sequence in the housing member 5 along the direction from the first surface 54 to the second surface 55, and the countersunk groove 533 of the one stage furthest from the second surface 55 is recessed in the direction from the first surface 54 toward the second surface 55, and the pressure relief area 56 is formed in the groove bottom wall 5331 of the countersunk groove of the one stage furthest from the first surface 54.

[0252] It should be explained that, regardless of whether the notched groove 532 in the groove portion 53 is single-stage or multi-stage, any of the groove portions 53 may include a multi-stage countersunk groove 533. As can be understood, the groove portion 53 has both the notched groove 532 and the countersunk groove 533, and the groove portion 53 is a multi-stage groove. The countersunk groove 533 and the notched groove 532 are disposed along a direction from the first surface 54 to the second surface 55. During molding, the housing member 5 may be molded with a multi-stage countersunk groove 533, and the notched groove 532 may be molded on the groove bottom wall 5331 of the single-stage countersunk groove furthest from the first surface 54.

[0253] The single-stage countersunk groove 533 farthest from the second surface 55 (closest to the first surface 54) is the outermost single-stage countersunk groove 533a, and the single-stage countersunk groove 533 farthest from the first surface 54 is the innermost single-stage countersunk groove 533b. The outermost single-stage countersunk groove 533a is disposed on the first surface 54, and the outermost single-stage countersunk groove 533a is recessed from the first surface 54 in a direction closer to the second surface 55.

[0254] The groove bottom wall 5331 of the one-stage countersunk groove farthest from the first surface 54 is a portion of the housing member 5 below the groove bottom surface of the one-stage countersunk groove 533 farthest from the first surface 54, and after forming the multi-stage countersunk grooves 533 in the housing member 5, the remaining portion in the region of the housing member 5 where the one-stage countersunk groove 533 farthest from the first surface 54 is provided is the groove bottom wall 5331 of the countersunk groove. As shown in Figs. 29, 31 and 33, the portion of the housing member 5 between the groove bottom surface of the one-stage countersunk groove 533 farthest from the first surface 54 and the second surface 55 is the groove bottom wall 5331 of the one-stage countersunk groove farthest from the first surface 54. Here, the pressure relief region 56 may be a part of the groove bottom wall 5331 of the one-stage countersunk groove farthest from the first surface 54.

[0255] The countersunk grooves 533 in the groove portion 53 may have two, three, four or more steps. Among two adjacent steps of the countersunk grooves 533, one step of the countersunk groove 533 farther from the first surface 54 is disposed on the bottom surface of the one step of the countersunk groove 533 closer to the first surface 54. The contour of the groove bottom surface of the multi-step countersunk grooves 533 decreases step by step along the direction from the first surface 54 to the second surface 55. The countersunk grooves 533 of each step can be formed in the housing member 5 by various methods, such as press molding, milling molding, and laser etching molding. For example, in the case where the countersunk grooves 533 of each step are formed in the housing member 5 by press molding, the countersunk grooves 533 of each step can be press molded in order along the direction from the first surface 54 to the second surface 55, and then the notched grooves 532 can be press molded. For example, if the countersunk grooves 533 in the groove portion 53 have two stages and the notched grooves 532 have one stage, during press molding, two presses are performed to form the two stages of the countersunk grooves 533, and then one press is performed to form the one stage of the notched grooves 532. As an example, in Figs. 28-33, the countersunk grooves 533 in the groove portion 53 have two stages.

[0256] When forming the multi-stage countersunk groove 533, the forming depth of each stage of the countersunk groove 533 can be reduced, which reduces the forming force that the housing member 5 receives when forming each stage of the countersunk groove 533, thereby reducing the risk of cracks occurring in the housing member 5. In addition, the multi-stage countersunk groove 533 can provide an escape space in the process of opening to the pressure relief area 56, so that even if the first surface 54 is blocked by an obstacle, the pressure relief area 56 can still open to relieve pressure.

[0257] In some embodiments, the interior space of the countersunk groove 533 is a cylinder, a prism, a truncated cone, or a truncated pyramid.

[0258] The internal space of the countersunk groove 533 is a space defined by the groove side surface and the groove bottom surface of the countersunk groove 533 in cooperation with each other. Here, the prismatic body may be a triangular prism, a square prism, a pentagonal prism, a hexagonal prism, etc., and the truncated pyramid body may be a triangular pyramid, a square prism, a pentagonal pyramid, a hexagonal pyramid, etc. For example, in FIG. 21-33, the internal space of the groove portion 53 is a square prism, specifically, the internal space of the groove portion 53 is a rectangular parallelepiped.

[0259] In this embodiment, the countersunk groove 533 has a simple structure, is easy to mold, and can provide more escape space in the process of opening to the pressure relief area 56 .

[0260] In some embodiments, referring to Fig. 34, Fig. 34 is a structural schematic diagram of a housing member 5 according to some embodiments of the present application (showing a V-shaped one-stage notched groove 532). The notched groove 532 includes a first groove section 5321 and a second groove section 5322, where the first groove section 5321 and the second groove section 5322 intersect, and the first groove section 5321 and the second groove section 5322 are disposed along the edge of the pressure relief area 56.

[0261] The first groove section 5321 and the second groove section 5322 may be straight grooves or may be non-straight grooves, for example arc-shaped grooves. In embodiments where the first groove section 5321 and the second groove section 5322 are both straight grooves, it can be understood that the first groove section 5321 and the second groove section 5322 both extend along a straight line, and the first groove section 5321 and the second groove section 5322 may be disposed at an acute angle, a right angle, or an obtuse angle. The first groove section 5321 and the second groove section 5322 may be arranged to intersect, for example, the intersection position of the first groove section 5321 and the second groove section 5322 may be located at the midpoint of the first groove section 5321 and the midpoint of the second groove section 5322, as shown in FIG. 34, the intersection position of the first groove section 5321 and the second groove section 5322 may be located at one end of the first groove section 5321 and one end of the second groove section 5322, the first groove section 5321 and the second groove section 5322 form a V-shaped structure, and the notched groove 532 is V-shaped.

[0262] In this embodiment, stress is concentrated at the intersection of the first groove section 5321 and the second groove section 5322, so that the weakened area 52 can be initially broken at the intersection of the first groove section 5321 and the second groove section 5322. When the explosion pressure of the battery cell 10 is constant, the weakened area 52 can be made thicker and the molding depth of the score groove 532 can be reduced.

[0263] In some embodiments, referring to Figures 9, 15, 22 and 28, the notched groove 532 may further include a third groove section 5323, where the first groove section 5321 and the third groove section 5323 are arranged opposite each other, the second groove section 5322 and the third groove section 5323 intersect, and the first groove section 5321, the second groove section 5322 and the third groove section 5323 are arranged along the edge of the pressure relief area 56.

[0264] The first groove section 5321, the second groove section 5322 and the third groove section 5323 may be straight grooves or may be non-straight grooves, for example, arc-shaped grooves. In an embodiment where the first groove section 5321, the second groove section 5322 and the third groove section 5323 are straight grooves, it can be understood that the first groove section 5321, the second groove section 5322 and the third groove section 5323 all extend along a straight line, and both the first groove section 5321 and the third groove section 5323 may be parallel or angled. Both the first groove section 5321 and the third groove section 5323 may be perpendicular to the second groove section 5322 or may not be perpendicular to the second groove section 5322.

[0265] The connection position between the second groove section 5322 and the first groove section 5321 may be located at one end of the first groove section 5321 or at a position offset from one end of the first groove section 5321. For example, the connection position between the second groove section 5322 and the first groove section 5321 is located at the midpoint of the first groove section 5321 in the extension direction, and the connection position between the second groove section 5322 and the third groove section 5323 may be located at one end of the third groove section 5323 or at a position offset from one end of the third groove section 5323. For example, the connection position between the second groove section 5322 and the third groove section 5323 is located at the midpoint of the third groove section 5323 in the extension direction.

[0266] It should be explained that in an embodiment in which the groove portion 53 includes a multi-stage groove 532, as can be understood, of two adjacent stages of grooves 532, the first groove section 5321 of the one-stage groove 532 away from the first surface 54 is located on the groove bottom surface of the first groove section 5321 of the one-stage groove 532 closer to the first surface 54, the second groove section 5322 of the one-stage groove 532 away from the first surface 54 is located on the groove bottom surface of the second groove section 5322 of the one-stage groove 532 closer to the first surface 54, and the third groove section 5323 of the one-stage groove 532 away from the first surface 54 is located on the groove bottom surface of the third groove section 5323 of the one-stage groove 532 closer to the first surface 54.

[0267] In this embodiment, the pressure relief area 56 can be opened using the first groove section 5321, the second groove section 5322 and the third groove section 5323 as boundaries, so that when the battery cell 10 is relieved from pressure, the pressure relief area 56 can be opened more easily, thereby realizing a large-area pressure relief for the housing member 5.

[0268] In some embodiments, with continued reference to Figures 9, 15, 22 and 28, the first groove section 5321, the second groove section 5322 and the third groove section 5323 define two pressure relief areas 56, each located on either side of the second groove section 5322.

[0269] For example, the first groove section 5321, the second groove section 5322 and the third groove section 5323 form an H-shaped notched groove 532, and the connection position between the second groove section 5322 and the first groove section 5321 is located at the midpoint of the first groove section 5321, and the connection position between the third groove section 5323 and the second groove section 5322 is located at the midpoint of the third groove section 5323. The two pressure relief areas 56 are symmetrically disposed on both sides of the second groove section 5322, and it can be seen that the areas of the two pressure relief areas 56 are equal. In other embodiments, the two pressure relief areas 56 may be asymmetrically located on either side of the second groove section 5322, so that the areas of the two pressure relief areas 56 are not equal, for example, the first groove section 5321 and the third groove section 5323 are both perpendicular to the second groove section 5322, the connection position between the second groove section 5322 and the first groove section 5321 is offset from the midpoint position of the first groove section 5321, and / or the connection position between the third groove section 5323 and the second groove section 5322 is located at the midpoint of the third groove section 5323.

[0270] The two pressure relief areas 56 are located on either side of the second groove section 5322, respectively, so that after the housing member 5 bursts at the position of the second groove section 5322, with the second groove section 5322 as the boundary, it can be split in half and opened along the first groove section 5321 and the third groove section 5323 to realize pressure relief, and the pressure relief efficiency of the housing member 5 can be effectively improved.

[0271] In some other embodiments, the first groove section 5321 , the second groove section 5322 and the third groove section 5323 are connected in sequence to define one pressure relief area 56 .

[0272] The first groove section 5321 , the second groove section 5322 and the third groove section 5323 may be connected in sequence to form a U-shaped notched groove 532 .

[0273] In some embodiments, the scored groove 532 is a groove that extends along a non-closed trajectory.

[0274] A non-closed locus is a locus whose both ends in the extension direction are not connected, and the non-closed locus may be an arc-shaped locus, a U-shaped locus, or the like.

[0275] In this embodiment, the notched groove 532 is a groove that follows a non-closed trajectory, and the pressure relief area 56 can be opened in an inverted manner and eventually connects to other areas of the housing member 5 after opening, reducing the risk of spatter occurring after the pressure relief area 56 opens.

[0276] In some embodiments, with reference to FIG. 11, as shown in FIGS. 17, 24 and 30, the notched grooves 532 are arc-shaped grooves.

[0277] An arc-shaped groove is a groove that extends along an arc-shaped path, the arc-shaped path being a non-closed path. The central angle of the arc-shaped groove may be less than, equal to, or greater than 180°.

[0278] The arc-shaped groove has a simple structure and is easy to mold. During the pressure relief process, the pressure relief area 56 can burst quickly along the arc-shaped groove, so that the pressure relief area 56 can open quickly.

[0279] In some embodiments, with reference to Figures 13, 19, 26 and 32, the scored groove 532 is a groove that extends along the closure trajectory.

[0280] A closed trajectory is a trajectory whose two ends are connected, and the closed trajectory may be a circular trajectory, a rectangular trajectory, etc.

[0281] During the pressure relief process, the housing member 5 can rupture along the notched grooves 532, thereby allowing the pressure relief area 56 to open to separate, increasing the pressure relief area of ​​the housing member 5 and improving the pressure relief speed of the housing member 5.

[0282] In some embodiments, the notched groove 532 is an annular groove.

[0283] The annular groove may be a rectangular annular groove or a circular annular groove.

[0284] The annular groove has a simple structure and is easy to mold, and in the pressure relief process, the housing member 5 can be quickly burst along the annular groove so that the pressure relief area 56 can be quickly opened.

[0285] In some embodiments, the area of ​​the pressure relief region 56 is D and is 90 mm 2 ≦D≦1500mm 2 Meet the following.

[0286] 9, 11, 13, 15, 17, 19, 22, 24, 26, 28, 30, 32 and 34, the area of ​​the shaded portion is the area of ​​the pressure relief region 56.

[0287] It should be noted that in an embodiment where groove portion 53 includes multiple levels of grooves 532, the area of ​​pressure relief region 56 is the area of ​​the region defined by the deepest (innermost) level of grooves 532.

[0288] D is 90mm 2 , 95mm 2 , 100mm 2 , 150mm 2 , 200mm 2 , 250mm 2 , 300mm 2 , 350mm 2 , 400mm 2 , 450mm 2 , 500mm 2 , 550mm 2 , 600mm 2 , 650mm 2 , 700mm 2 , 750mm 2 , 800mm 2 , 900mm 2 , 950mm 2 , 1000mm 2 , 1050mm 2 , 1100mm 2 , 1150mm 2 , 1200mm 2 , 1250mm 2 , 1300mm 2 , 1350mm 2 , 1400mm 2 , 1450mm 2 , 1500mm 2 It may be any one of the values ​​or a range between any two of them.

[0289] D<90mm 2 In the case of D>1500 mm, the pressure release area of ​​the housing member 5 is small, and the pressure release immediateness during thermal runaway of the battery cell 10 is poor. 2 In this case, the impact resistance of the pressure relief area 56 is poor, the pressure relief area 56 is deformed significantly after being subjected to a force, and the fragile area 52 is easily broken under normal use conditions of the battery cell 10, which affects the service life of the battery cell 10. 2 ≦D≦1500mm 2 In this case, the service life of the battery cell 10 can be extended and the safety of the battery cell 10 can be improved.

[0290] In addition, 150mm 2 ≦D≦1200mm 2 Therefore, the housing member 5 has better overall performance, a larger pressure relief area, and good impact resistance.

[0291] In addition, 200mm 2 ≦D≦1000mm 2 It is.

[0292] In addition, 250mm 2 ≦D≦800mm 2 It is.

[0293] 4-34, in some embodiments, the housing member 5 has a first surface 54 and a second surface 55 disposed opposite to each other, the groove portion 53 is recessed in a direction from the first surface 54 toward the second surface 55 to form an outer edge 534 in the first surface 54, and an area of ​​the housing member 5 that is separated from the outer edge 534 by a predetermined distance or more is the non-weakened area 51. Here, the predetermined distance is L.

[0294] L may be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc.

[0295] 9-14, the groove portion 53 includes only one stage of the knurled groove 532, the knurled groove 532 is disposed on the first surface 54, the groove side of the knurled groove 532 and the first surface 54 intersect to form an outer edge 534, and the groove side of the knurled groove 532 surrounds the circumference of the groove bottom surface of the knurled groove 532. It should be noted that in the embodiment shown in FIG. 13, the knurled groove 532 is a groove extending along a closed locus, so the groove side of the knurled groove 532 and the first surface 54 intersect to form an inner ring line and an outer ring line located outside the inner ring line, and the outer ring line is the outer edge 534.

[0296] 15-20, the groove portion 53 only includes a multi-step knurled groove 532, and the outermost one-step knurled groove 532a is disposed on the first surface 54, and the groove side of the outermost one-step knurled groove 532a and the first surface 54 intersect to form an outer edge 534. It should be noted that in the embodiment shown in FIG. 19, the knurled groove 532 is a groove extending along a closed locus, so the outermost one-step knurled groove 532a and the first surface 54 intersect to form an inner loop line and an outer loop line located outside the inner loop line, and the outer loop line is the outer edge 534.

[0297] 21 to 27, the groove portion 53 further includes a one-stage countersunk groove 533, the countersunk groove 533 is disposed on the first surface 54, a groove side surface of the countersunk groove 533 and the first surface 54 intersect to form an outer edge 534, and the groove side surface of the countersunk groove 533 surrounds the periphery of the groove bottom surface of the countersunk groove 533. In the embodiment shown in FIGS. 28 to 33, the groove portion 53 further includes multiple-stage countersunk grooves 533, and an outermost one-stage countersunk groove 533a is disposed on the first surface 54, and a groove side surface of the outermost one-stage countersunk groove 533a and the first surface 54 intersect to form the outer edge 534.

[0298] As can be understood, the distance between the outer edge 534 and the inner edge 511 of the non-weakened region 51 is a preset distance L, and the shape of the inner edge 511 of the non-weakened region 51 may be essentially the same as the shape of the outer edge 534. The direction of the preset distance L may be perpendicular to the thickness direction of the non-weakened region 51, that is, the preset distance L may be measured along the thickness direction perpendicular to the non-weakened region 51. When measuring the average grain size of the non-weakened region 51, it may be measured in a region that is at least the preset distance away from the outer edge 534.

[0299] In this embodiment, the area that is more than a predetermined distance away from the outer edge 534 of the housing member 5 is the non-weakened area 51, and the non-weakened area 51 and the groove portion 53 are separated by a certain distance, so that the non-weakened area 51 is less affected by the molding process of the groove portion 53, and therefore the crystal grains of the non-weakened area 51 become more uniform.

[0300] In some embodiments, L=5 mm.

[0301] It should be explained that in an embodiment in which the first groove section 5321 and the third groove section 5323 of the notched groove 532 are disposed opposite to each other as shown in Fig. 9 and Fig. 15, taking the first groove section 5321 and the third groove section 5323 as an example in which they are parallel, when the distance between the first groove section 5321 and the third groove section 5323 is greater than 2*L, the inner edge 511 of the non-weakened area 51 is partially located in the pressure relief area 56, so that the pressure relief area 56 is partially located in the non-weakened area 51. In another embodiment, referring to Fig. 35, Fig. 35 is a structural schematic diagram of a housing member 5 according to another embodiment of the present application, when the distance between the first groove section 5321 and the third groove section 5323 is less than or equal to 2*L, the inner edge 511 of the non-weakened area 51 is not located in the pressure relief area 56, and the inner edge 511 of the non-weakened area 51 is approximately rectangular. Along the width direction of the first groove section 5321, the spacing between the first groove section 5321 and the inner edge 511 of the non-weakened region 51 is L, along the length direction of the first groove section 5321, the spacing between the first groove section 5321 and the inner edge 511 of the non-weakened region 51 is L, along the width direction of the third groove section 5323, the spacing between the third groove section 5323 and the inner edge 511 of the non-weakened region 51 is L, and along the length direction of the third groove section 5323, the spacing between the third groove section 5323 and the inner edge 511 of the non-weakened region 51 is L.

[0302] In some embodiments, referring to Fig. 36, Fig. 36 is a grain diagram (schematic diagram) of a housing member 5 according to some embodiments of the present application. The housing member 5 further includes a transition region 57, the transition region 57 connecting the weakened region 52 and the non-weakened region 51, and the average grain size of the transition region 57 is S3, where S3 < S2.

[0303] For example, S3>S1.

[0304] The transition region 57 is a part of the housing member 5 that connects the weak region 52 and the non-weakened region 51, and is disposed surrounding the outside of the weak region 52, the non-weakened region 51 surrounding the outside of the transition region 57, and the weak region 52, the transition region 57, and the non-weakened region 51 are integrally molded.

[0305] The average crystal grain size of the transition region 57 may gradually decrease from the non-weakened region 51 to the weak region 52. For example, as shown in FIG. 36 , when the groove portion 53 includes one step of the countersunk groove 533 and one step of the notched groove 532, the average crystal grain size of the transition region 57 in the outer region of the countersunk groove 533 may be larger than the average crystal grain size of the transition region 57 in the bottom region of the countersunk groove 533, the average crystal grain size of the transition region 57 in the outer region of the countersunk groove 533 may be equal to or smaller than the average crystal grain size S2 of the non-weakened region 51, and the average crystal grain size of the transition region 57 in the bottom region of the countersunk groove 533 may be larger than the average crystal grain size S1 of the weak region 52.

[0306] In this embodiment, the transition region 57 serves to connect the weakened region 52 and the non-weakened region 51, and allows the weakened region 52 and the non-weakened region 51 to be integrally formed.

[0307] In some embodiments, referring to Fig. 37, Fig. 37 is a structural schematic diagram of an end cap 11 according to some embodiments of the present application. The housing member 5 is the end cap 11 for closing the opening of the case 12, and the case 12 is used to house the electrode assembly 2.

[0308] As can be seen, a groove 53 is provided in the end cap 11 to form a weakened area 52 and a non-weakened area 51. The first surface 54 and the second surface 55 of the housing member 5 are two opposing surfaces in the thickness direction of the end cap 11, i.e., one of the first surface 54 and the second surface 55 is an inner surface in the thickness direction of the end cap 11, and the other is an outer surface in the thickness direction of the end cap 11.

[0309] The end cap 11 may be a circular or rectangular plate-like structure.

[0310] For example, in the embodiment shown in FIG. 37, the end cap 11 is a rectangular plate-like structure.

[0311] In this embodiment, the end cap 11 has a pressure relief function and ensures the safety of the battery cell 10.

[0312] 38 and 39, in some embodiments, Fig. 38 is a structural schematic diagram of the case 12 according to some embodiments of the present application, and Fig. 39 is a structural schematic diagram of the case 12 according to some other embodiments of the present application. The housing member 5 is the case 12 having an opening for accommodating the electrode assembly 2.

[0313] In this embodiment, the case 12 of the housing 1 is the housing member 5, and the end cap 11 of the housing 1 is used to close the opening of the case 12. The case 12 may be a hollow structure with an opening at one end, or may be a hollow structure with openings at both opposing ends. The case 12 may be a rectangular parallelepiped, a cylindrical body, or the like.

[0314] In this embodiment, the housing member 5 is a case 12, and the safety of the battery cells 10 is ensured by providing the case 12 with a pressure relief function.

[0315] In some embodiments, the case 12 includes a plurality of walls 121 that are integrally molded together and cooperate to define an interior space of the case 12, and at least one of the walls 121 includes a groove 53 disposed therein.

[0316] In the case 12, the groove 53 may be provided in one wall portion 121 so as to form a weakened region 52 and a non-weakened region 51 that are integrally molded in the wall portion 121, or the groove 53 may be provided in a plurality of wall portions 121 so as to form a weakened region 52 and a non-weakened region 51 that are integrally molded in each wall portion 121 in which the groove 53 is provided. With respect to the wall portion 121 in which the groove 53 is provided, the first surface 54 and the second surface 55 of the housing member 5 are two opposing surfaces in the thickness direction of the wall portion 121, respectively, that is, one of the first surface 54 and the second surface 55 is an inner surface in the thickness direction of the wall portion 121, and the other is an outer surface in the thickness direction of the wall portion 121.

[0317] In this embodiment, the walls 121 are integrally formed, so that the walls 121 of the groove 53 have high reliability.

[0318] 38 and 39, in some embodiments, the walls 121 include a bottom wall 121b and a plurality of side walls 121a surrounding the periphery of the bottom wall 121b, and the case 12 has an opening at an end opposite the bottom wall 121b. A groove 53 is provided in the bottom wall 121b and / or a groove 53 is provided in at least one of the side walls 121a.

[0319] In this embodiment, the case 12 has a hollow structure with an opening at one end. The number of side walls 121a in the case 12 may be three, four, five, six or more. One, two, three, four, five, six or more grooves 53 may be provided in the side wall 121a.

[0320] For example, in FIG. 38, a groove portion 53 is provided in only one side wall 121a so as to form a weak area 52 and a non-weakened area 51 in this side wall 121a, and in FIG. 39, a groove portion 53 is provided in only the bottom wall 121b so as to form a weak area 52 and a non-weakened area 51 in the bottom wall 121b.

[0321] In some embodiments, with continued reference to Figures 38 and 39, case 12 is a rectangular parallelepiped.

[0322] As can be seen, the case 12 has four side walls 121a.

[0323] The rectangular parallelepiped case is applicable to a square battery cell and can meet the large capacity requirement of the battery cell 10.

[0324] In some embodiments, the material of the housing member 5 includes an aluminum alloy.

[0325] The housing member 5 made of an aluminum alloy has a light weight, excellent ductility, excellent plastic deformation ability, and is easy to form.

[0326] In the embodiment where 0.1≦S1 / S2≦0.5, the aluminum alloy has excellent ductility, and when forming the groove portion 53 in the housing member 5 by a press method, it is easy to control S1 / S2 to 0.5 or less (including 0.5), and the forming yield is higher.

[0327] In some embodiments, the aluminum alloy includes aluminum≧99.6%, copper≦0.05%, iron≦0.35%, magnesium≦0.03%, manganese≦0.03%, silicon≦0.25%, titanium≦0.03%, vanadium≦0.05%, zinc≦0.05%, and other single elements≦0.03% by weight. Such an aluminum alloy has lower hardness and better forming ability, which reduces the difficulty of forming the groove 53, improves the forming precision of the groove 53, and improves the pressure relief consistency of the housing member 5.

[0328] In some embodiments, the aluminum alloy includes aluminum >= 96.7%, 0.05% <= copper <= 0.2%, iron <= 0.7%, manganese <= 1.5%, silicon <= 0.6%, zinc <= 0.1%, other single elemental components <= 0.05%, other total elemental components <= 0.15%, by weight. The housing member 5 made of such an aluminum alloy has higher hardness, higher strength, and better fracture resistance.

[0329] An embodiment of the present application provides a battery cell 10 including a housing member 5 according to any one of the above embodiments.

[0330] In some embodiments, the battery cell 10 further includes a case 12 having an opening for housing the electrode assembly 2. The housing member 5 is an end cap 11 that closes the opening.

[0331] In some embodiments, the housing member 5 is a case 12 having an opening for housing the electrode assembly 2. The battery cell 10 further includes an end cap 11 that closes the opening.

[0332] An embodiment of the present application provides a battery 100 including a battery cell 10 according to any one of the above embodiments.

[0333] 40 is a structural schematic diagram of the battery cell 10 according to some embodiments of the present application. In some embodiments, referring to FIG. 40, the weak area 52 is located at the bottom of the battery cell 10.

[0334] In the battery cell 10, a portion of the battery cell 10 below the mid-plane Y of the housing 1 along the height direction of the battery cell 10 is the lower part of the battery cell 10, where the mid-plane Y is perpendicular to the height direction of the housing 1, and the distances from the mid-plane Y to the two end faces of the housing 1 in the height direction are equal. For example, the housing 1 includes a case 12 and an end cap 11 that closes an opening of the case 12. The case 12 and the end cap 11 are arranged along the height direction of the housing 1, and the mid-plane Y is located midway between the outer surface of the end cap 11 opposite the case 12 and the outer surface of the case 12 opposite the end cap 11 along the height direction of the housing 1.

[0335] The weak region 52 is located at the bottom of the battery cell 10, and the groove portion 53 is located at the bottom of the battery cell 10, and both the weak region 52 and the groove portion 53 are located below the mid-plane Y. The weak region 52 may be located at the case 12 or at the end cap 11. The weak region 52 may be located at the side wall 121a of the case 12 or at the bottom wall 121b of the case 12. As shown in FIG. 40 , for example, in the case where the weak region 52 is located at the side wall 121a of the case 12, the bottom wall 121b of the case 12 may be located below the end cap 11, and the weak region 52 may be located below the mid-plane Y, so that the distance from the weak region 52 to the bottom wall 121b of the case 12 is greater than the distance from the weak region 52 to the end cap 11.

[0336] Since the weak area 52 is located at the bottom of the battery cell 10, the weak area 52 is subjected to a large force under the gravitational action of the electrode assembly 2 and electrolyte inside the battery cell 10 during use of the battery 100. Since the weak area 52 and the non-weak area 51 are formed as an integral structure, it has excellent structural strength and high reliability, thereby extending the service life of the battery cell 10.

[0337] In some embodiments, the battery cell 10 includes a case 12, the case 12 is used to house the electrode assembly 2, and includes an integrally molded bottom wall 121b and a plurality of side walls 121a surrounding the periphery of the bottom wall 121b, the bottom wall 121b and the side walls 121a are integrally molded, the case 12 has an opening formed at an end opposite the bottom wall 121b, and the weak area 52 is located in the bottom wall 121b.

[0338] As can be seen, the bottom wall 121b is located below the mid-plane Y.

[0339] In this embodiment, the vulnerable area 52 is located on the bottom wall 121b, and by setting the vulnerable area 52 facing downward, when the battery cell 10 experiences thermal runaway, the vulnerable area 52 is destroyed and then the waste material from the battery cell 10 is ejected downward, thereby reducing the risk of a safety accident occurring. For example, in the vehicle 1000, the battery 100 is generally mounted below the passenger compartment, and by setting the vulnerable area 52 facing downward, the waste material emitted by the battery cell 10 experiencing thermal runaway is ejected in the direction opposite to the passenger compartment, thereby reducing the impact of the waste material on the passenger compartment and reducing the risk of a safety accident occurring.

[0340] In some embodiments, the battery cell 10 includes an end cap 11, which is used to close an opening of a case 12, which is used to house the electrode assembly 2, and the weakened area 52 is located in the end cap 11.

[0341] As can be seen, the end caps 11 are located below the mid-plane Y.

[0342] In this embodiment, the weak area 52 is located on the end cap 11, and the weak area 52 is arranged facing downward. In the event of thermal runaway of the battery cell 10, the weak area 52 is destroyed, and then the waste material in the battery cell 10 is ejected downward, thereby reducing the risk of a safety accident occurring.

[0343] An embodiment of the present application provides a power consuming device including a battery 100 according to any one of the above embodiments.

[0344] In some embodiments, the present application provides an end cap 11 for a battery cell 10, the end cap 11 including an integrally molded non-weakened area 51 and a weakened area 52. The end cap 11 is provided with a groove 53, the non-weakened area 51 is formed around the groove 53, and the weakened area 52 is formed at the bottom of the groove 53, and the weakened area 52 is configured to break when the battery cell 10 releases internal pressure. The end cap 11 has a first surface 54 opposite to the inside of the battery cell 10, the groove 53 forms an outer edge 534 on the first surface 54, and an area of ​​the end cap 11 that is more than a preset distance away from the outer edge 534 is the non-weakened area 51, and the preset distance is L, where L=5 mm. The average crystal grain size of the weak region 52 is S1, the average crystal grain size of the non-weakened region 51 is S2, the minimum thickness of the weak region 52 is A, the minimum thickness of the non-weakened region 51 is B, the hardness of the weak region 52 is H1, and the hardness of the non-weakened region 51 is H2. 0.1≦S1 / S2≦0.5, 5≦A / S1≦20, 190HBW / mm≦H1 / A≦4000HBW / mm, 1

[0345] ​In some embodiments, the present application provides a case 12 for a battery cell 10, the case 12 including a non-weakened area 51 and a weak area 52 that are integrally molded. The case 12 is provided with a groove 53, the non-weakened area 51 is formed around the groove 53, and the weak area 52 is formed at the bottom of the groove 53, and the weak area 52 is configured to break when the battery cell 10 releases internal pressure. The case 12 has a first surface 54 opposite to the inside of the battery cell 10, the groove 53 forms an outer edge 534 on the first surface 54, and an area of ​​the case 12 that is more than a preset distance away from the outer edge 534 is the non-weakened area 51, and the preset distance is L, where L=5 mm. The average crystal grain size of the weak region 52 is S1, the average crystal grain size of the non-weakened region 51 is S2, the minimum thickness of the weak region 52 is A, the minimum thickness of the non-weakened region 51 is B, the hardness of the weak region 52 is H1, and the hardness of the non-weakened region 51 is H2. 0.1≦S1 / S2≦0.5, 5≦A / S1≦20, 190HBW / mm≦H1 / A≦4000HBW / mm, 1

[0346] The features and performance of the present application will be described in more detail below in conjunction with examples.

[0347] In each of the examples and comparative examples, the battery cell 10 is a rectangular battery cell, the end cap 11 of the battery cell 10 is a housing member 5, the capacity of the battery cell 10 is 150 Ah, and the chemical system is NCM.

[0348] 1. Test method

[0349] (1) Average grain size test of the weakly weakened area 52 and the non-weakly weakened area 51.

[0350] ​The average grain size test of the weak area 52 and the non-weak area 51 was performed using the electron backscatter diffraction (EBSD) method. The housing member 5 was cut into three parts, and the cross sections at both ends of the middle part both had the weak area 52 and the non-weak area 51. The cutting direction was perpendicular to the longitudinal direction of the weak area 52, and the cutting device did not change the grain structure. After the middle part was selected and sampled, and the sample was electrolytically polished, the sample was fixed on a sample stage tilted at 70°, an appropriate magnification was selected, and an EBSD scan was performed with a scanning electron microscope (SEM) equipped with an electron backscatter diffraction (EBSD) member, and finally the average grain size (i.e., the equal area circle diameter of the complete grain in the inspection surface) was calculated based on the scan results.

[0351] (2) Minimum thickness test of the weakened area 52 and non-weakened area 51.

[0352] The housing member 5 was cut into three parts, and the middle part was used as a sample, and the cross sections at both ends of the sample had a weak region 52 and a non-weakened region 51. The cutting direction was perpendicular to the longitudinal direction of the weak region 52. After the cross section of the middle part was polished to thoroughly remove burrs, the sample was placed on a three-dimensional coordinate measuring machine, and the thicknesses of the weak region 52 and the non-weakened region 51 in the cross section were measured.

[0353] (3) Hardness testing of the weakened area 52 and the non-weakened area 51.

[0354] The housing member 5 was cut into three parts, and the middle part was used as a sample, and the cross sections at both ends of the sample had a weak area 52 and a non-weakened area 51. The cutting direction was perpendicular to the longitudinal direction of the weak area 52, and the test cross section was polished to thoroughly remove burrs, after which the sample was placed horizontally on a Brinell hardness tester (the cross-sectional direction of the sample was parallel to the pressing direction of the hardness tester) to measure the hardness. If the width of the weak area 52 was <1mm or the size of the indenter of the Brinell hardness tester was much larger than the width of the weak area 52, a non-standard indenter should be processed to measure the hardness according to the Brinell hardness measurement and conversion principle.

[0355] (4) The rate at which the weak area 52 cracks under normal conditions of use of the battery cell 10.

[0356] The battery cells 10 were left at 25±2°C and cycle-charged and discharged at a charge / discharge interval of 5%-97% SOC, the gas generation pressure inside the battery cells 10 was monitored, and 500 sets of tests were performed. The test was terminated when the life of the battery cells 10 was reduced to 80% SOH or when a crack occurred in the weak area 52 during the cycle process of any one of the battery cells 10. Here, the condition for determining whether the weak area 52 had cracks was that the internal air pressure value of the battery cell 10 had decreased and the reduction value was >10% of the maximum air pressure. The crack rate of the weak area 52 was calculated as follows: crack rate=number of cracks / total number*100%.

[0357] (5) Explosion rate of battery cell 10 in the event of thermal runaway.

[0358] A small heating film was built into the battery cell 10, and electricity was passed through the heating film to heat the battery cell 10 until the battery cell 10 went into thermal runaway, and it was observed whether the battery cell 10 exploded. 500 sets of tests were repeated, and the explosion rate of the battery cells 10 was calculated, and the explosion rate was calculated as number of explosions / total number*100%.

[0359] 2. Test results

[0360] In each embodiment and comparative example, the test results for the average crystal grain size S1 of the weak region 52, the average crystal grain size S2 of the non-weakened region 51, the minimum thickness A of the weak region 52, the minimum thickness B of the non-weakened region 51, the hardness H1 of the weak region 52, and the hardness H2 of the non-weakened region 51 are shown in Table 1, where the units for S1 and S2 are mm, the units for A and B are mm, and the units for H1 and H2 are HBW. The crack rate Q1 of the weak region 52 under normal usage conditions of the battery cell 10 and the explosion rate Q2 during thermal runaway of the battery cell 10 are shown in Table 2.

[0361] [Table 1]

[0362] JPEG2025511582000003.jpg112166

[0363]

Table 2

[0364] As can be seen from Examples 1 to 7 by combining Table 1 and Table 2, when S1 / S2 ≤ 0.9, the crack rate of the vulnerable area 52 under normal use conditions of the battery cell 10 was low. In Comparative Example 1, 0.9 < S1 / S2 < 1, and the crack rate of the vulnerable area 52 under normal use conditions of the battery cell 10 clearly increased. In Comparative Example 2, S1 / S2 = 1, and the crack rate of the vulnerable area 52 under normal use conditions of the battery cell 10 clearly increased. In Comparative Example 3, S1 / S2 > 1, and the crack rate of the vulnerable area 52 under normal use conditions of the battery cell 10 also clearly increased. As can be seen from the comparison between Examples 1 to 7 and Comparative Examples 1 to 3, by controlling S1 / S2 to 0.9 or less, the risk that the vulnerable area 52 is destroyed under normal use conditions of the battery cell 10 can be effectively reduced, thereby extending the service life of the battery cell 10.

[0365] As can be seen from Example 7, when S1 / S2 < 0.05, the difficulty of the vulnerable area 52 being destroyed during thermal runaway of the battery cell 10 increases, the pressure release is not timely, and the risk of the battery cell 10 exploding clearly increases. As can be seen from Examples 3 to 5, when 0.1 ≤ S1 / S2 ≤ 0.5, both the crack rate of the vulnerable area 52 under normal use conditions of the battery cell 10 and the explosion rate during thermal runaway of the battery cell 10 are low. While ensuring that the vulnerable area 52 can be destroyed in a timely manner during thermal runaway of the battery cell 10, it is ensured that the vulnerable area 52 has sufficient strength under normal use conditions of the battery cell 10.

[0366] As can be seen from a comparison of Examples 9 to 12 with Example 8, when 1≦A / S1≦100, pressure could be released in a timely manner during thermal runaway of the battery cell 10, and the explosion rate of the battery cell 10 was low. When 5≦A / S1≦20, the overall performance of the battery cell 10 was better, and the crack rate of the vulnerable area 52 under normal usage conditions of the battery cell 10 and the explosion rate during thermal runaway of the battery cell 10 were both low.

[0367] As can be seen from a comparison between Examples 14 to 17 and Example 13, when H1 / A>10,000 HBW / mm, the crack rate of the weak region 52 under normal use conditions of the battery cell 10 was high, and as can be seen from a comparison between Examples 14 to 17 and Example 18, when H1 / A<5 HBW / mm, the explosion rate during thermal runaway of the battery cell 10 was high. When 5 HBW / mm≦H1 / A≦10,000 HBW / mm, it is possible to reduce the risk of the weak region 52 exploding under normal use conditions of the battery cell 10, and it is possible for the weak region 52 to release pressure in a timely manner during thermal runaway of the battery cell 10, thereby reducing the risk of the battery cell 10 exploding. As can be seen from Examples 15 and 16, when 190 HBW / mm≦H1 / A≦4000 HBW / mm, the overall performance of the battery cell 10 was better, and the crack rate of the weak area 52 under normal usage conditions of the battery cell 10 and the explosion rate during thermal runaway of the battery cell 10 were both low.

[0368] As can be seen from a comparison between Examples 19-21 and Examples 22-23, when H1 / H2≦1, the crack rate of the weak area 52 under normal usage conditions of the battery cell 10 was high. When H1 / H2>1, it was possible to effectively reduce the crack rate of the weak area 52 under normal usage conditions of the battery cell 10. As can be seen from a comparison between Examples 20-21 and Example 19, when H1 / H2>5, the explosion rate of the battery cell 10 during thermal runaway was high. When H1 / H2≦5, it was possible to reduce the risk of the battery cell 10 exploding.

[0369] As can be seen from the comparison of Examples 25 to 30 with Example 24, when A / B>0.95, the explosion rate of the battery cell 10 during thermal runaway was high. As can be seen from the comparison of Examples 25 to 30 with Example 31, when A / B<0.05, the crack rate of the weak area 52 under normal use conditions of the battery cell 10 was high. When 0.05≦A / B≦0.95, the risk of the weak area 52 bursting under normal use conditions of the battery cell 10 can be reduced, and the weak area 52 can release pressure in a timely manner during thermal runaway of the battery cell 10, thereby reducing the risk of the battery cell 10 exploding. As can be seen from Examples 26 to 29, when 0.12≦A / B≦0.8, the overall performance of the battery cell 10 was better, and both the crack rate of the weak area 52 under normal use conditions of the battery cell 10 and the explosion rate of the battery cell 10 during thermal runaway were low, and when 0.2≦A / B≦0.5, more excellent effects were obtained.

[0370] It should be mentioned that, unless there is a conflict, the embodiments and features in the embodiments in the present application can be combined with each other.

[0371] The above examples are only intended to explain the technical solution of the present application, and are not intended to limit the present application, and those skilled in the art may make various modifications and variations to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the protection scope of the present application.

Claims

1. A housing member for a battery cell, the housing member including a non-weakened area and a weakened area that are integrally molded, the housing member being provided with a groove, the non-weakened area being formed around the groove, and the weakened area being formed at a bottom of the groove, the weakened area being configured to break when the battery cell releases internal pressure; Here, the average crystal grain size of the fragile region is S １ The average grain size of the non-weakened region is S ２ And S １ / S ２ A housing member satisfying a ratio of ≦0.

9.

2. S １ / S ２ 2. The housing member of claim 1, wherein the .lambda.R.sub.2 is .gtoreq.0.

05.

3. 0.1≦S １ / S ２ 3. A housing member according to claim 1 or 2, wherein the axial length of the housing is ≦0.

5.

4. 0.4 μm≦S １ ≦75 μm, preferably 1 μm≦S １ A housing member according to any one of claims 1 to 3, wherein the thickness is ≦10 μm.

5. 10 μm≦S ２ ≦150 μm, preferably 30 μm≦S ２ A housing member according to any one of claims 1 to 4, wherein the thickness is ≦100 μm.

6. The minimum thickness of the weakened region is A, where 1≦A / S １ ≦100, preferably 5≦A / S １ 6. The housing member according to claim 1, wherein the thickness of the housing member is less than or equal to 20.

7. The minimum thickness of the weakened area is A and the hardness of the weakened area is H １ and 5HBW / mm≦H １ / A≦10000HBW / mm, preferably 190HBW / mm≦H １ The housing member according to claim 1 , wherein / A≦4000 HBW / mm is satisfied.

8. 8. A housing member according to claim 7, wherein 0.02 mm≦A≦1.6 mm, preferably 0.06 mm≦A≦0.4 mm.

9. The hardness of the weakened area is H １ , the hardness of the non-weakened region is H ２ And H １ >H ２ The housing member according to claim 1 , wherein the above formula (1) is satisfied.

10. H １ / H ２ ≦5, preferably H １ / H ２ 10. The housing member of claim 9, wherein the axial length is ≦2.

5.

11. 5HBW≦H ２ 11. A housing member according to claim 9 or 10, having a hardness of ≦150 HBW.

12. 5HBW≦H １ 12. A housing member according to any one of claims 7 to 11, wherein the hardness is ≦200 HBW.

13. 13. A housing member according to claim 1, wherein the weakened area has a minimum thickness A and the non-weakened area has a minimum thickness B, satisfying 0.05≦A / B≦0.95, preferably 0.12≦A / B≦0.8, preferably 0.2≦A / B≦0.

5.

14. A housing member according to claim 13, wherein 0.02 mm≦A≦1.6 mm, preferably 0.06 mm≦A≦0.4 mm.

15. A housing member according to claim 13 or 14, wherein 1 mm≦B≦5 mm, preferably 1.2 mm≦B≦3.5 mm, preferably 2 mm≦B≦3 mm.

16. 16. A housing member according to claim 1, wherein the housing member has a pressure relief area, the groove portion includes a one-stage notched groove, the notched groove is located along an edge of the pressure relief area, the pressure relief area is configured to be openable using the notched groove as a boundary, and the weakened area forms a bottom of the notched groove.

17. 17. The housing member of claim 16, wherein the housing member has oppositely disposed first and second surfaces, and the groove is recessed in a direction from the first surface toward the second surface.

18. the housing member includes a first surface and a second surface disposed opposite to each other, the groove portion includes a multi-stage notched groove, the multi-stage notched groove is disposed in order on the housing member along a direction from the first surface to the second surface, and the weakened area is formed at a bottom of the notched groove of one stage furthest from the first surface; A housing member according to any one of claims 1 to 15, wherein the housing member has a pressure relief area, the notched grooves of each stage are arranged along the edge of the pressure relief area, and the pressure relief area is configured so that it can open at the boundary of the notched groove of one stage that is farthest from the first surface.

19. The housing member according to claim 18 , wherein the groove of the step furthest from the second surface is recessed in a direction from the first surface toward the second surface.

20. 19. The housing member according to claim 16 or 18, wherein the housing member includes a first surface and a second surface arranged opposite each other, the groove portion further includes a one-stage countersunk groove, the countersunk groove is recessed in a direction from the first surface toward the second surface, and the pressure relief area is formed in a groove bottom wall of the countersunk groove.

21. 19. The housing member according to claim 16 or 18, wherein the housing member includes a first surface and a second surface arranged opposite each other, the groove portion further includes a multi-stage countersunk groove, the multi-stage countersunk grooves being arranged in sequence in the housing member along a direction from the first surface to the second surface, the countersunk groove of one stage furthest from the second surface being recessed in a direction from the first surface toward the second surface, and the pressure relief area is formed in a groove bottom wall of the countersunk groove of the one stage furthest from the first surface.

22. The housing member according to claim 20 or 21, wherein the internal space of the countersunk groove is a cylinder, a prism, a truncated cone or a truncated pyramid.

23. 23. A housing member according to any one of claims 16 to 22, wherein the notched groove includes a first groove section and a second groove section, the first groove section and the second groove section intersecting and located along an edge of the pressure relief area.

24. 24. The housing member of claim 23, wherein the notched groove further includes a third groove section, the first groove section and the third groove section are disposed opposite each other, the second groove section and the third groove section intersect, and the first groove section, the second groove section and the third groove section are disposed along an edge of the pressure relief area.

25. 25. The housing member of claim 24, wherein the first groove section, the second groove section and the third groove section are connected in sequence to define one of the pressure relief areas.

26. 25. The housing member of claim 24, wherein the first groove section, the second groove section and the third groove section define two of the pressure relief areas, each of the two pressure relief areas being located on either side of the second groove section.

27. 23. A housing member according to any one of claims 16 to 22, wherein the scored groove is a groove extending along a non-closed locus.

28. 28. A housing member according to any one of claims 16 to 22 and 27, wherein the notched groove is an arc-shaped groove.

29. 23. A housing member according to any one of claims 16 to 22, wherein the scored groove is a groove extending along a closing locus.

30. 30. A housing member according to any one of claims 16 to 22 and 29, wherein the groove is an annular groove.

31. The area of ​​the pressure relief area is D and is 90 mm ２ ≦D≦1500mm ２ , preferably 150 mm ２ ≦D≦1200mm ２ , preferably 200 mm ２ ≦D≦1000mm ２ , preferably 250 mm ２ ≦D≦800mm ２ 31. The housing member according to any one of claims 16 to 30, wherein

32. 32. The housing member according to claim 1, wherein the housing member has a first surface and a second surface arranged opposite each other, the groove portion is recessed from the first surface in a direction toward the second surface and forms an outer edge on the first surface, and an area of ​​the housing member that is at least a predetermined distance away from the outer edge is the non-weakened area.

33. 33. The housing member of claim 32, wherein the preset distance is L and satisfies L = 5 mm.

34. The housing member further includes a transition region connecting the weakened region and the non-weakened region, the transition region having an average grain size of S ３ And S ３ ≦S ２ 34. The housing member according to claim 1, wherein

35. 35. The housing member of claim 1, wherein the housing member is an end cap, the end cap being used to close an opening of a case, and the case being used to house an electrode assembly.

36. 35. The housing member according to claim 1, wherein the housing member is a case having an opening for housing an electrode assembly.

37. 37. The housing member of claim 36, wherein the case includes a plurality of walls integrally molded together, the walls cooperating to define an interior space of the case, and at least one of the walls has the groove disposed therein.

38. The plurality of wall portions include a bottom wall and a plurality of side walls surrounding the periphery of the bottom wall, and the opening is formed in the case at an end opposite to the bottom wall, The bottom wall is provided with a groove; and / or 38. The housing member of claim 37, wherein at least one of the side walls is provided with the groove.

39. 39. A housing member according to any one of claims 36 to 38, wherein the case is a rectangular parallelepiped.

40. 40. The housing member of claim 1, wherein a material of the housing member includes an aluminum alloy.

41. 41. The housing member of claim 40, wherein the aluminum alloy comprises: aluminum > 99.6%, copper < 0.05%, iron < 0.35%, magnesium < 0.03%, manganese < 0.03%, silicon < 0.25%, titanium < 0.03%, vanadium < 0.05%, zinc < 0.05%, and any other single element < 0.03%, by weight.

42. 41. The housing member of claim 40, wherein the aluminum alloy comprises, by weight, >96.7% aluminum, 0.05% <= copper <= 0.2%, <= 0.7%, <= 1.5%, by weight manganese, <= 0.6%, <= 0.1%, by weight zinc, <= 0.05%, by weight other single elemental components, and <= 0.15%, by weight total other elemental components.

43. A battery cell, 43. A battery cell comprising a housing member according to any one of claims 1 to 42.

44. The battery cell further includes a case having an opening for housing the electrode assembly; 44. The battery cell of claim 43, wherein the housing member is an end cap closing the opening.

45. the housing member is a case having an opening for accommodating an electrode assembly; 44. The battery cell of claim 43, wherein the battery cell further includes an end cap closing the opening.

46. 46. ​​A battery comprising a battery cell according to any one of claims 43 to 45.

47. 47. The battery of claim 46, wherein the weakened area is located at a bottom of the battery cell.

48. 48. The battery of claim 47, wherein the battery cell includes a case, the case is used to house an electrode assembly, the case includes a bottom wall and a plurality of side walls surrounding the bottom wall, the bottom wall and the side walls are integrally molded, the case has an opening formed at an end opposite the bottom wall, and the weakened area is located in the bottom wall.

49. 48. The battery of claim 47, wherein the battery cell includes an end cap, the end cap is used to close an opening of a case, the case is used to house an electrode assembly, and the weakened area is located in the end cap.

50. 50. A power consumer device comprising a battery according to any one of claims 46 to 49.

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