Batteries and batteries

Abstract

The present invention relates to the field of battery technology, and discloses a battery and a battery pack, wherein the battery comprises: a cover plate assembly, a shell and a battery cell, wherein the shell comprises a bottom wall, wherein one side of the bottom wall facing the inside of the shell is concave to form a groove portion; the wall thickness of the bottom wall is locally thinned to form a weak portion, and the weak portion is formed in the groove portion, and the weak portion is formed by stamping; the residual thickness of the weak portion is h1, and the depth of the groove portion is D; the width of the groove portion is m, and satisfies: 0.005≤h1·(D·m)≤18. The battery provided by the present invention forms the weak portion in the groove portion; thereby leaving a gap between the weak portion and the external plane, and when the weak portion is formed, even if the material flows to the surroundings and causes the flatness at the position of the weak portion to deteriorate, the shell will not be partially lifted, thereby avoiding causing the battery to be in a tilted state and reducing the risk of cold welding of the tab.

Description

Technical Field

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

[0002] The battery is equipped with an explosion-proof valve. In the related art, the explosion-proof valve is integrally formed at the bottom of the shell by locally thinning. When the explosion-proof valve is thinned during stamping, the material will flow to the surrounding area, resulting in poor flatness of the shell at the explosion-proof valve, which can easily cause the battery height to exceed the tolerance (excess tolerance means that the product's external dimensions exceed the tolerance range specified in the product standard), which in turn can easily lead to the risk of cold solder joints on the tabs. Summary of the invention

[0003] In view of this, the present invention provides a battery and a battery pack to solve the problem that after the explosion-proof valve is formed, the flatness of the shell at the explosion-proof valve is poor and there is a risk of cold welding of the tab.

[0004] The present invention provides a battery, comprising a cover plate assembly, a shell and a battery cell, wherein the shell is provided with an opening, the cover plate assembly is arranged at the opening of the shell, and the cover plate assembly comprises a pole assembly; the shell comprises a bottom wall, the bottom wall and the cover plate assembly are arranged opposite to each other, and a side of the bottom wall facing the inside of the shell is recessed to form a groove portion; the wall thickness of the bottom wall is locally thinned to form a weak portion, the weak portion is formed in the groove portion, and the weak portion is formed by stamping;

[0005] The residual thickness of the weak part is h1, the depth of the groove part is D, and the width of the groove part is m, satisfying: 0.005≤h1·(D·m)≤18.

[0006] Beneficial effect: In the battery provided by the embodiment of the present invention, a part of the bottom wall is recessed toward one side of the opening to form a groove portion; the wall thickness of the bottom wall is locally thinned to form a weak portion suitable for pressure relief, and the weak portion is formed in the groove portion; so that a gap is left between the weak portion and the external plane. When the weak portion is formed, even if the material flows to the surroundings and causes the flatness at the position of the weak portion to deteriorate, the shell will not be partially lifted, thereby avoiding the battery from being in a tilted state and reducing the risk of cold welding of the tab; by comprehensively controlling the relationship between the residual thickness h1 of the weak portion, the depth D of the groove portion and the width m of the groove portion, the problem of poor surface flatness of the shell caused by the material squeezed out during stamping of the weak portion can be reduced; at the same time, the problem of the groove portion being too deep and occupying the internal space of the battery is avoided; and / or the problem of poor flatness of the bottom surface of the shell caused by the excessive width of the groove portion is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0008] Figure 1 Schematic diagram of the battery of the present invention Figure 1 ;

[0009] Figure 2 Schematic diagram of the battery of the present invention Figure 2 ;

[0010] Figure 3 is a schematic cross-sectional view of a battery of the present invention;

[0011] Figure 4 A front view of the bottom wall of the battery of the present invention;

[0012] Figure 5 for Figure 4 A partial enlarged view of the AA section;

[0013] Figure 6 It is a partial enlarged view of the housing of the present invention;

[0014] Figure 7 It is a cross-sectional view of the internal structure of the battery cell of the present invention.

[0015] Description of reference numerals:

[0016] 1. Shell; 11. Groove portion; 111. Groove bottom surface; 112. Transition portion; 12. Weak portion; 13. Liquid injection hole; 14. Bottom wall; 15. Bottom wall body; 16. Air storage chamber;

[0017] 2. Cover plate assembly; 3. Battery cell; 31. Battery cell body; 311. Positive electrode sheet; 312. Negative electrode sheet; 313. Diaphragm; 32. Tab; 4. Sealing plug. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0019] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] The battery is provided with an explosion-proof valve. The explosion-proof valve can have a variety of structural forms. One is to provide a through hole on the shell, and then set the explosion-proof plate in the through hole to form an explosion-proof valve; the other is to form the explosion-proof valve in one piece by locally thinning the shell. For the one-piece explosion-proof valve, when the explosion-proof valve is stamped and thinned, the material will flow to the surroundings, resulting in poor flatness of the shell at the explosion-proof valve, and the shell will be partially lifted, which may easily cause the battery to be in a tilted state, making it impossible to ensure that the poles on the top of the battery are in the same plane, and then easily lead to the risk of cold welding of the bar piece, which includes the bus. In addition, when the explosion-proof valve is stamped and thinned, the battery height will be out of tolerance, which is prone to dimensional errors.

[0023] Combine the following Figures 1 to 7 , describing an embodiment of the present invention.

[0024] According to an embodiment of the present invention, there is provided a battery, comprising:

[0025] Cover plate assembly 2, housing 1 and battery cell 3;

[0026] The housing 1 is provided with an opening, the cover assembly 2 is provided at the opening of the housing 1, and the cover assembly 2 includes a pole assembly; the housing 1 includes a bottom wall, the bottom wall and the cover assembly 2 are arranged opposite to each other, and the bottom wall 14 is recessed on one side facing the inside of the housing 1 to form a groove portion 11; the wall thickness of the bottom wall 14 is partially thinned to form a weak portion 12, and the weak portion 12 is formed in the groove portion 11, and the weak portion 12 is formed by stamping;

[0027] The residual thickness of the weak portion 12 is h1, the depth of the groove portion 11 is D, and the width of the groove portion 11 is m, which satisfies: 0.005≤h1·(D·m)≤18.

[0028] In this embodiment, the battery includes a shell 1, a battery cell 3 and a cover assembly 2, wherein the shell 1 is provided with an opening, specifically, the opening may be formed at one end of the shell 1 along the axial direction, or at both ends of the shell 1 along the axial direction. The battery cell 3 is loaded into the shell 1 from the opening, and the cover assembly 2 is buckled into the opening of the shell 1, thereby enclosing the battery cell 3 inside the battery.

[0029] The cover plate assembly 2 includes a pole assembly, which may include a pole and a current collecting element connected to the pole, so that the current collecting element serves as an intermediate connecting piece between the pole and the pole lug.

[0030] The housing 1 includes a bottom wall. In this embodiment, an opening is formed at one end of the housing 1 along the axial direction. The bottom wall refers to the wall surface at the end opposite to the opening. It should be noted that since the battery may be placed lying down, the bottom wall is not the bottom of the housing 1 along the height direction.

[0031] The end of the shell 1 opposite to the opening forms a bottom wall 14 , that is, the cover plate assembly 2 and the bottom wall 14 of the shell 1 are arranged opposite to each other, and the cover plate assembly 2 is used for electrically connecting to the busbar.

[0032] The bottom wall 14 is provided with a liquid injection hole 13 for injecting electrolyte into the battery. After the electrolyte injection is completed, the sealing plug 4 is inserted into the liquid injection hole 13 to seal the liquid injection hole 13 and prevent leakage.

[0033] The bottom wall 14 is recessed on one side facing the inside of the housing 1 to form a groove 11 ; the groove 11 is arched toward the battery cell 3 , and when the bottom wall 14 of the battery is placed on an external plane, a gap is left between the groove 11 and the external plane.

[0034] Taking the battery as a cylindrical battery as an example, the wall thickness of the bottom wall 14 along the axial direction is locally thinned to form a weak portion 12 suitable for pressure relief. The weak portion 12 is used to crack when the battery has thermal runaway to release gas from the inside of the battery. When the battery has thermal runaway, since the structural strength of the weak portion 12 is lower than that of other areas of the shell 1, the internal gas will preferentially break through the weak portion 12, thereby bursting for exhaust.

[0035] The weak portion 12 is formed in the groove portion 11 and is integrally formed in the form of local thinning. In this embodiment, the weak portion 12 is formed by stamping. Since the material will flow to the surrounding when the weak portion 12 is stamped and thinned, the flatness of the shell 1 at the position of the weak portion 12 will deteriorate. In this embodiment, the weak portion 12 is formed in the groove portion 11, so that a gap is left between the weak portion 12 and the external plane. That is, when the weak portion 12 is formed, even if the material will flow to the surrounding and cause the flatness at the position of the weak portion 12 to deteriorate, the shell 1 will not be partially lifted, so as to avoid causing the battery to be in a tilted state. Since multiple batteries need to be connected in series and parallel through a bus when the batteries are subsequently grouped, if the battery flatness is poor, it will cause a cold solder joint when the bus and the battery are electrically connected. In this embodiment, the weak portion 12 is formed in the groove portion 11, so that the poles at the top of the battery can be ensured to be in the same plane, reducing the risk of cold solder joints on the bus. In addition, in some embodiments, the battery housing 1 may serve as an electrical connection output terminal. By forming the weak portion 12 in the groove portion 11, the battery can be prevented from being in a tilted state. It is also possible to ensure that multiple batteries are arranged in parallel, thereby ensuring effective electrical connection between the batteries.

[0036] In the battery provided by the embodiment of the present invention, a partial area of ​​the bottom wall 14 is recessed toward one side of the opening to form a groove portion 11; the wall thickness of the bottom wall 14 along the axial direction is locally thinned to form a weak portion 12 suitable for pressure relief, and the weak portion 12 is formed in the groove portion 11; thereby, a gap is left between the weak portion 12 and the external plane. When the weak portion 12 is formed, even if the material flows to the surroundings and causes the flatness at the position of the weak portion 12 to deteriorate, the shell 1 will not be partially lifted, thereby avoiding causing the battery to be in a tilted state and reducing the risk of poor solder joints in the tabs.

[0037] The residual thickness of the weak part 12 is h1, and the depth of the groove part 11 is D; the width of the groove part 11 is m. The smaller the residual thickness h1 of the weak part 12, the more material will be squeezed out during stamping. At this time, D·m needs to be larger to accommodate more squeezed material and avoid material accumulation and being squeezed onto the surface of the shell 1, resulting in poor surface flatness of the shell 1. Since the pole needs to be electrically connected to the busbar later, poor surface flatness of the shell will affect the welding of the pole and the busbar, resulting in an increased risk of false welding; conversely, the larger the residual thickness h1 of the weak part 12, the smaller D·m can be appropriately adjusted;

[0038] This embodiment can reduce the problem of poor surface flatness of the shell 1 caused by the material squeezed out during stamping of the weak portion 12 by comprehensively controlling the relationship between the residual thickness h1 of the weak portion 12, the depth D of the groove portion 11, and the width m of the groove portion 11; at the same time, it also avoids the problem of the groove portion 11 being too deep and occupying the internal space of the battery; and / or the problem of poor flatness of the bottom surface of the shell caused by the groove portion 11 being too wide.

[0039] In this embodiment, combined with Figure 6 As shown, the depth D of the groove portion 11 refers to the distance between the bottom wall of the groove and the bottom surface of the shell; the forming form of the groove portion 11 is not limited. In this embodiment, the groove portion 11 can be formed by stamping.

[0040] In some embodiments, the ratio of the residual thickness h1 of the weak portion 12 to the thickness h2 of the bottom wall 14 is H, that is, H=h1 / h2, satisfying: H≤0.4;

[0041] At this time, D·m satisfies: 0.1≤D·m≤60.

[0042] The smaller the ratio H of the residual thickness h1 of the weak portion 12 to the thickness h2 of the bottom wall 14 is, the more material is squeezed out during stamping. At this time, D·m needs to be larger to accommodate more squeezed material and avoid material accumulation and being squeezed onto the surface of the shell 1, resulting in poor surface flatness of the shell 1.

[0043] In this embodiment, the value of H can specifically be 0.025 or 0.05 or 0.1 or 0.15 or 0.2 or 0.25 or 0.3 or the like.

[0044] H cannot be too large, otherwise it will be detrimental to the bursting of the weak portion 12 and affect the smooth release of the gas inside the battery; H cannot be too small either, otherwise the weak portion 12 may burst abnormally.

[0045] In some embodiments, the width m of the groove portion 11 satisfies: 0.8 mm ≤ m ≤ 20 mm;

[0046] And / or, the depth D of the groove portion 11 satisfies: 0.1 mm≤D≤3 mm.

[0047] The width m of the groove 11 cannot be too small. If it is too small, the material will be easily squeezed out of the groove 11. At this time, in order to accommodate enough material, the depth D of the groove 11 needs to be too large, which will cause the internal space of the battery shell to be occupied.

[0048] By controlling the lower limit of the depth D of the groove 11, it is possible to avoid the situation in which the material of the weak portion 12 caused by the groove 11 being too small flows to the surroundings during stamping, causing the edge material in the groove 11 to be squeezed to the surface of the bottom wall 14, thereby avoiding the flatness of the bottom wall 14 to deteriorate and the shell 1 to be partially lifted; by controlling the upper limit of the depth D of the groove 11, it is possible to avoid the groove 11 being arched too high toward the inside of the shell 1, thereby preventing the excessive occupation of the space of the battery cell 3 and ensuring the energy density of the battery.

[0049] The battery may be a cylindrical battery, and the width of the groove 11 refers to its size along the radial direction of the battery; the battery may be a square shell battery, and the width of the groove 11 refers to its size along the length direction of the battery.

[0050] In this embodiment, the value of m can specifically be 0.8 mm or 1.2 mm or 2.3 mm or 4.5 mm or 6.2 mm or 7.4 mm or 8.8 mm or 10 mm or 12 mm or 13.8 mm or 15 mm or 17 mm or 18.2 mm or 19 mm or 20 mm, etc.

[0051] In this embodiment, the value of D can specifically be 0.1 mm or 0.5 mm or 0.8 mm or 1.2 mm or 1.5 mm or 1.9 mm or 2 mm or 2.2 mm or 2.5 mm or 3 mm, etc.

[0052] In some embodiments, the weak portion 12 is a V-shaped groove. In this case, the depth D of the groove portion 11 satisfies: 0.1 mm≤D≤1.5 mm.

[0053] In this embodiment, the weak portion 12 is a V-shaped groove, which is convenient for stamping, and when thermal runaway occurs, the pressure of the V-shaped groove is concentrated in a narrower place, which can make the weak portion 12 burst more quickly. In addition, when the weak portion 12 is a V-shaped groove, the cross-sectional area of ​​the notch of the V-shaped groove is larger than the cross-sectional area of ​​the groove bottom, and less material is extruded during stamping, and the corresponding depth D of the groove portion 11 can be set smaller, which can prevent material accumulation from being squeezed onto the surface of the shell 1.

[0054] In this embodiment, the value of D can specifically be 0.1 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, etc.

[0055] In some other embodiments, the weak portion 12 is a rectangular groove. In this case, the depth D of the groove portion 11 satisfies: 0.15 mm≤D≤2 mm.

[0056] In this embodiment, the weak portion 12 is a rectangular groove. During normal charging and discharging, heat is also generated inside the battery. The weak portion 12 is set as a rectangular groove. When the gas inside the battery cell impacts, the bottom cross-sectional area of ​​the rectangular groove is large, and the risk of abnormal explosion of the weak portion 12 is small. In addition, when the weak portion 12 is a rectangular groove, the cross-sectional area of ​​the notch of the rectangular groove is equal to the cross-sectional area of ​​the bottom of the groove. Compared with the V-shaped groove, more materials are extruded during stamping, and the corresponding depth D of the groove portion 11 needs to be larger to accommodate more extruded materials, so as to avoid the accumulation of materials being squeezed onto the surface of the shell 1, resulting in poor surface flatness of the shell 1.

[0057] In this embodiment, the value of D can specifically be 0.15 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.9 mm, 2 mm, etc.

[0058] In some embodiments, the weak portion 12 and / or the groove portion 11 are constructed as a continuous ring, and the area adjacent to the bottom wall 14 and the groove portion 11 is defined as the bottom wall body 15; the bottom wall body 15 and the battery cell 3 are spaced apart, and the diameter of the battery cell 3 is N, satisfying: 0.02≤m / N≤0.45.

[0059] Since the bottom wall body 15 and the battery cell 3 are arranged at intervals, the area between the bottom wall body 15 and the battery cell 3 will form a gas storage space. When the weak portion 12 and / or the groove portion 11 is configured as a continuous ring, since the groove portion 11 is arched toward the battery cell 3 around the entire circumference of the battery, the gas storage space between the bottom wall body 15 and the battery cell 3 will be occupied, resulting in a reduction in the gas storage space. Therefore, it is necessary to control the upper limit of the ratio of the width m of the groove portion 11 to the diameter N of the battery cell 3, thereby ensuring the size of the gas storage space. On the contrary, when the weak portion 12 or the groove portion 11 is configured as a discontinuous ring, the gas storage space between the bottom wall body 15 and the battery cell 3 will increase.

[0060] The width of the groove portion 11 is m. By limiting the range of m / N, when m / N is larger, the width ratio of the groove portion 11 is wider, and the size of the corresponding bottom wall body 15 area is narrower, which easily leads to insufficient exhaust space. On the contrary, when m / N is smaller, the width ratio of the groove portion 11 is narrower, which easily leads to insufficient accommodation space of the groove portion 11, and then the material squeezed out when the weak portion 12 is punched is squeezed to the surface of the shell 1, resulting in poor surface flatness of the shell 1.

[0061] In some embodiments, the battery cell 3 includes a battery cell body 31 and a tab 32 , the tab 32 is led out from a side of the battery cell body 31 away from the weak portion 12 , and the battery cell body 31 includes a positive electrode sheet 311 , a negative electrode sheet 312 and a separator 313 ;

[0062] Along the axial direction, the length of the separator 313 beyond the negative electrode sheet 312 is b, which satisfies:

[0063] 0.5mm≤b≤5mm.

[0064] In this embodiment, by setting the groove portion 11 on the bottom wall 14 of the shell 1, the problem of poor flatness of the bottom wall 14 caused by material accumulation during the stamping process of the weak portion 12 is avoided; however, after the battery cell 3 is placed inside the shell 1, the flatness of the battery cell 3 also needs to be ensured. Since the bottom wall 14 is recessed on one side toward the inside of the shell 1 to form the groove portion 11, the battery cell 3 may be in a tilted state inside the shell 1. The diaphragm 313 is relatively soft in texture, and the diaphragm 313 can absorb a part of the tolerance caused by the stamping groove portion 11, ensuring that the battery cell 3 will not tilt after being placed inside the shell 1. Therefore, by setting the lower limit of the length b of the diaphragm 313 exceeding the negative electrode sheet 312, it can be ensured that the diaphragm 313 exceeds the length of the negative electrode sheet 312, and even if the battery cell is tilted, there is enough diaphragm to contact the shell, reducing the risk of damage to the electrode sheet. By limiting the upper limit of b, the diaphragm 313 is prevented from exceeding the length of the negative electrode sheet 312 too much to affect the electrolyte infiltration, etc. If the diaphragm 313 exceeds too much, it is easy to be drawn out by negative pressure when the battery is filled with liquid, causing the diaphragm 313 to block the injection hole and affect the injection.

[0065] The length b of the separator 313 beyond the negative electrode sheet 312 is called Overhang (negative electrode excess design), and its purpose is to ensure the insulation effect between the battery cell and the shell.

[0066] Additionally, along the axial direction, the negative electrode sheet 312 is arranged beyond the positive electrode sheet 311. The portion where the negative electrode sheet 312 exceeds the positive electrode sheet 311 is to reduce lithium deposition and ensure that after the positive electrode sheet 311 is de-lithiated, the negative electrode sheet 312 has sufficient space for lithium insertion. Therefore, the size of the negative electrode generally exceeds the size of the positive electrode.

[0067] In this embodiment, the value of b can specifically be 0.5 mm or 0.8 mm or 1 mm or 1.2 mm or 1.4 mm or 1.5 mm or 1.9 mm or 2 mm or 2.5 mm or 3 mm or 4.2 mm or 4.8 mm or 5 mm, etc.

[0068] In some embodiments, the notch of the weak portion 12 faces toward the battery cell 3 and / or faces away from the battery cell 3 .

[0069] The weak portion 12 is integrally stamped and formed on the housing 1; the side of the bottom wall 14 located inside the housing 1 is defined as the inner side wall, and the side of the bottom wall 14 located outside the housing 1 is defined as the outer side wall;

[0070] The weak portion 12 is formed by punching from the inner wall toward the outer wall;

[0071] Alternatively, the weak portion 12 is formed by punching the outer wall toward the inner wall;

[0072] Alternatively, the weak portion 12 is formed by punching the outer wall and the inner wall toward opposite sides at the same time. At this time, by punching from the inside and outside of the shell 1 respectively, the punching depth of the inner and outer sides can be reduced accordingly, and the strength of the groove portion 11 can also be increased.

[0073] The projection shape of the groove portion 11 on the bottom wall 14 is circular, rectangular, I-shaped or fan-shaped;

[0074] The projection shape of the weak portion 12 on the bottom wall 14 is circular, rectangular, I-shaped or fan-shaped.

[0075] In some embodiments, the groove portion 11 and / or the weak portion 12 are symmetrically distributed relative to the central axis of the battery, and the residual thickness h1 of the weak portion 12 satisfies: 0.05 mm ≤ h1 ≤ 0.27 mm;

[0076] The groove portion 11 and / or the weak portion 12 are eccentrically distributed relative to the central axis of the battery, and the residual thickness h1 of the weak portion 12 satisfies: 0.04 mm≤h1≤0.25 mm.

[0077] As an implementation form, when the groove portion 11 and / or the weak portion 12 are symmetrically distributed relative to the central axis of the battery, during stamping, the bottom wall 14 of the shell is evenly stressed on both sides of the central axis of the battery, thereby avoiding uneven stress on one side of the shell. Since the central axis of the battery is generally provided with a liquid injection hole 13, by symmetrically distributing the groove portion 11 and / or the weak portion 12 relative to the central axis of the battery, it is possible to avoid one side being too close to the position of the liquid injection hole 13, thereby preventing the structural strength of the shell at the position of the liquid injection hole 13 from being affected. In addition, since a weak portion 12 needs to be provided in the groove portion 11, it is easier to implement in terms of process by adopting a symmetrical distribution.

[0078] As another implementation form, when the groove portion 11 and / or the weak portion 12 are eccentrically distributed relative to the central axis of the battery, the weak portion 12 will be broken through when the gas inside the battery is depressurized. By eccentrically setting the groove portion 11 and / or the weak portion 12 relative to the central axis of the battery, the impacts on both sides of the central axis of the battery are different, which can reduce the probability of the battery cell flying out of the shell. Because when the groove portion 11 and / or the weak portion 12 are symmetrically distributed relative to the central axis of the battery, when the weak portion 12 explodes, the weak portions 12 on both sides of the central axis of the battery will be opened at the same time due to balanced force, which will cause the weak portion to fly out with part of the shell, which may easily cause the battery cell to fly out. When the groove portion 11 and / or the weak portion 12 are eccentrically distributed relative to the central axis of the battery, it may happen that when the weak portion 12 explodes, one side of the central axis of the battery has been opened, while the other side is still connected to the shell, thereby reducing the probability of the battery cell flying out of the shell.

[0079] When the grooves 11 and / or the weak parts 12 are symmetrically distributed relative to the central axis of the battery, the weak parts 12 on both sides of the central axis of the battery will open at the same time due to balanced force, which may cause the battery cell to fly out. Therefore, the residual thickness h1 of the weak parts 12 needs to be larger to reduce the possibility of the battery cell flying out. In addition, the residual thickness h1 of the weak parts 12 cannot be too large, otherwise it will cause the internal gas of the battery to be difficult to release.

[0080] When the groove portion 11 and / or the weak portion 12 are eccentrically distributed relative to the central axis of the battery, the residual thickness h1 of the weak portion 12 can be appropriately smaller because the risk of the battery cell flying out is relatively small.

[0081] In addition, no matter the groove is eccentric or symmetrical, the groove size can be consistent or inconsistent.

[0082] It should be noted that, no matter the groove portion 11 and / or the weak portion 12 are eccentrically distributed or symmetrically distributed relative to the central axis of the battery, the depth D of the groove portion 11 may be consistent or inconsistent; the width m of the groove portion 11 may be consistent or inconsistent.

[0083] In some embodiments, the bottom wall 14 is provided with a plurality of groove portions 11 .

[0084] By increasing the number of the grooves 11 , it is possible to play the role of reinforcing ribs, thereby increasing the structural strength of the bottom wall 14 and reducing deformation.

[0085] In some embodiments, the material of the housing 1 includes steel, and the residual thickness h1 of the weak portion 12 satisfies: 0.003 mm ≤ h1 ≤ 0.2 mm;

[0086] The depth D of the groove portion 11 satisfies: 0.13 mm ≤ D ≤ 0.3 mm.

[0087] Optionally, the material of the shell 1 may be aluminum or steel, etc. In the present embodiment, the material of the shell 1 includes steel. When the shell of the battery is made of steel, such as stainless steel, nickel-plated steel, etc., the steel shell has high tensile strength and yield strength, which makes the explosion-proof valve easier to rupture when under pressure. Under the same blasting conditions, in order for the subsequent weak part 12 to be able to explode successfully, the explosion-proof valve needs to have a small residual thickness. Due to the thin residual thickness, more material is squeezed out during stamping; the corresponding depth D of the groove portion 11 needs to be appropriately increased. In some other embodiments, the shell may also be made of aluminum, specifically, aluminum alloy, aluminum-manganese alloy, etc.

[0088] In addition, since the weak portion 12 is relatively thin, if it is directly disposed on the bottom surface of the shell, the influence of external pressure will also increase, and the probability of abnormal damage is high. In this embodiment, the weak portion 12 is disposed in the groove portion 11, which can prevent the weak portion 12 from abnormally cracking due to other external pressures. This prevents the explosion-proof valve from rupture due to accidental pressure, improves product stability, and reduces the defective rate.

[0089] In addition, the groove portion 11 formed on the bottom wall 14 can play a role similar to a reinforcing rib to increase the structural strength of the bottom wall 14 .

[0090] In some embodiments, in combination Figure 5 , Figure 6 As shown, the area where the bottom wall 14 and the groove portion 11 are adjacent is defined as the bottom wall body 15;

[0091] The groove portion 11 includes a groove bottom surface 111 and a transition portion 112 connected between the groove bottom surface 111 and the bottom wall body 15;

[0092] The weak portion 12 is disposed on the groove bottom surface 111 .

[0093] Setting the weak portion 12 on the groove bottom surface 111 can protect the weak portion 12 to the greatest extent. On the one hand, it can leave more space for accommodating the stamping material; on the other hand, it can also protect the weak portion; on the other hand, it is easier to operate during stamping. If the weak portion 12 is set on other groove walls, the angle will be inclined during stamping, which is not easy to stamp.

[0094] Combination Figure 6 As shown, when the bottom wall 14 of the battery is placed on the external plane, a gap is left between the bottom surface 111 of the groove and the external plane. The battery provided by the embodiment of the present invention can leave a gap between the weak portion 12 and the external plane by arranging the weak portion 12 on the bottom surface 111 of the groove. When the weak portion 12 is formed, even if the material flows to the surroundings and causes the flatness at the position of the weak portion 12 to deteriorate, the shell 1 will not be partially lifted, thereby avoiding the battery being in a tilted state and reducing the risk of cold solder joints in the tabs.

[0095] The transition portion 112 connected between the groove bottom surface 111 and the bottom wall body 15 may be in the form of an arc angle to facilitate the forming of the groove portion 11 .

[0096] In some embodiments, in combination Figure 5 As shown, a battery cell 3 is arranged inside the housing 1;

[0097] At least a portion of the bottom wall body 15 is spaced apart from the battery core 3 to form a gas storage cavity 16 .

[0098] The area adjacent to the bottom wall 14 and the groove portion 11 is the bottom wall body 15. In the present embodiment, a portion of the bottom wall 14 is recessed toward the opening side to form the groove portion 11, that is, the groove portion 11 is arched toward the battery cell 3. Correspondingly, the bottom wall body 15 and the battery cell 3 are spaced apart, so that the area corresponding to the bottom wall body 15 and the battery cell 3 forms an air storage cavity 16. The setting of the air storage cavity 16 can increase the air storage space inside the battery.

[0099] Since the battery produces gas during the charge and discharge process, causing excessive internal pressure in the battery, if the gas storage space inside the battery is small and the gas production is large and cannot be discharged in time, the explosion-proof valve (that is, the weak portion 12) will open before the preset valve opening time, causing the explosion-proof valve to open abnormally. If the opening strength of the explosion-proof valve is increased, the battery will be under excessive pressure, posing a risk of explosion.

[0100] In this embodiment, at least a portion of the bottom wall body 15 is spaced apart from the battery cell 3 to form a gas storage cavity 16, thereby increasing the gas storage capacity during thermal runaway and reducing the risk of battery explosion.

[0101] It is worth noting that the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator are wound or stacked to form a battery cell 3; the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. There is no special restriction on the positive electrode current collector, as long as it has conductivity and does not cause adverse chemical changes in the battery, and can use, for example: stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc.; the negative electrode current collector can be copper, stainless steel, nickel, titanium, etc., and a composite current collector can also be used. The composite current collector refers to a polymer layer in the middle, and metal layers are arranged on the opposite sides of the polymer layer. The metal layer can be made of copper, stainless steel, nickel, titanium, etc.; in a specific embodiment, the positive electrode current collector can be aluminum, and the negative electrode current collector can be copper. The positive electrode active material layer includes positive electrode active materials, which include nickel-cobalt-manganese ternary materials, lithium iron phosphate materials, lithium manganese iron phosphate materials, etc.; the negative electrode active material layer includes negative electrode active materials, which include artificial graphite, natural graphite, silicon-based materials, etc.

[0102] According to another aspect of an embodiment of the present invention, a battery pack is provided, comprising: a battery and a bus bar, wherein the bus bar comprises a pole connecting portion.

[0103] In this embodiment, the explosion-proof valve and the busbar are arranged on opposite sides, and the weak portion 12 is the explosion-proof valve. The weak portion 12 is formed by stamping. When the weak portion 12 is stamped and thinned, the material will flow to the surroundings, resulting in poor flatness of the shell 1 at the position of the weak portion 12. In this embodiment, the weak portion 12 is formed in the groove portion 11, so that a gap is left between the weak portion 12 and the external plane. That is, when the weak portion 12 is formed, even if the material will flow to the surroundings and cause the flatness at the position of the weak portion 12 to deteriorate, the shell 1 will not be partially lifted, thereby avoiding causing the battery to be in a tilted state. When the batteries are subsequently grouped, multiple batteries need to be connected in series and parallel through the busbar, and the busbar includes a pole connection portion. If the battery has poor flatness, it will cause a cold weld when the busbar and the battery are electrically connected. In this embodiment, the weak portion 12 is formed in the groove portion 11, so that the poles at the top of the battery can be ensured to be in the same plane, thereby reducing the risk of cold welds on the busbar.

[0104] In some embodiments, the cap assembly includes a cap body and a pole, and the busbar further includes a cap body connecting portion, wherein the pole connecting portion is connected to the pole of the battery, and the cap body connecting portion is connected to the cap body of another battery.

[0105] In this embodiment, the cover body of the battery will also serve as an electrical connection output terminal, and the busbar connects the batteries in series. The busbar includes a pole connection portion and a cover body connection portion, which respectively connect the pole of one battery cell and the cover body of another battery cell. By forming the weak portion 12 in the groove portion 11, the battery is prevented from being in a tilted state, and multiple batteries can also be ensured to be in a parallel arrangement state, ensuring effective electrical connection between the batteries and avoiding the risk of cold welding of the busbar.

[0106] In some embodiments, the battery can be a cylindrical battery, and the cylindrical battery shell serves as one of the electrode output ends, which will be electrically connected to the bus later; the cover assembly includes a cover body, and the electrode group assembly is arranged on the cover body. The cover body is circular, and the diameter of the cover body is less than or equal to 60 mm; the diameter of the cover body is small, and the electrode group assembly needs to be arranged on the cover body, resulting in a relatively small area for electrically connecting the bus. If a cold weld occurs, the flow area will be affected. Therefore, it is necessary to further control the product of the depth D of the groove portion and the width m of the groove portion to meet the range of 0.12-60, so as to avoid causing poor flatness of the bottom wall of the shell, resulting in cold welds on the bus, and causing a serious reduction in the flow area of ​​the battery.

[0107] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. A battery, characterized in that: The invention comprises a cover plate assembly (2), a shell (1) and a battery cell (3), wherein the shell (1) is provided with an opening, the cover plate assembly (2) is arranged at the opening of the shell (1), and the cover plate assembly (2) comprises a pole assembly; the shell (1) comprises a bottom wall, the bottom wall and the cover plate assembly (2) are arranged opposite to each other, the bottom wall (14) is recessed on one side facing the inside of the shell (1) to form a groove portion (11); the wall thickness of the bottom wall (14) is locally thinned to form a weak portion (12), the weak portion (12) is formed in the groove portion (11), and the weak portion (12) is formed by stamping; The residual thickness of the weak portion (12) is h1, the depth of the groove portion (11) is D; the width of the groove portion (11) is m, and the following conditions are satisfied: 0.005≤h1·D·m≤18; The width m of the groove portion (11) satisfies: 0.8 mm ≤ m ≤ 20 mm; The depth D of the groove portion (11) satisfies: 0.1 mm ≤ D ≤ 3 mm.

2. The battery according to claim 1, characterized in that The ratio of the residual thickness h1 of the weak portion (12) to the thickness h2 of the bottom wall (14) is H, that is, H=h1 / h2, satisfying: H≤0.4; At this time, D·m satisfies: 0.1≤D·m≤60.

3. The battery according to claim 1, characterized in that The weak portion (12) is a V-shaped groove, and in this case, the depth D of the groove portion (11) satisfies: 0.1 mm ≤ D ≤ 1.5 mm.

4. The battery according to claim 1, characterized in that The weak portion (12) is a rectangular groove, and in this case, the depth D of the groove portion (11) satisfies: 0.15 mm ≤ D ≤ 2 mm.

5. The battery according to claim 1, characterized in that The weak portion (12) and / or the groove portion (11) are constructed as a continuous ring, and the area where the bottom wall (14) and the groove portion (11) are adjacent is defined as a bottom wall body (15); the bottom wall body (15) and the battery cell (3) are arranged at intervals, and the diameter of the battery cell (3) is N, satisfying: 0.02≤m / N≤0.

45.

6. The battery according to claim 1, characterized in that The battery cell (3) comprises a battery cell body (31) and a pole ear (32), wherein the pole ear (32) is led out from a side of the battery cell body (31) away from the weak portion (12), and the battery cell body (31) comprises a positive electrode sheet (311), a negative electrode sheet (312) and a separator (313); Along the axial direction, the length of the separator (313) beyond the negative electrode sheet (312) is b, satisfying: 0.5 mm ≤ b ≤ 5 mm.

7. The battery according to claim 1, characterized in that The notch of the weak portion (12) faces the battery core (3), and / or faces away from the battery core (3).

8. The battery according to claim 1, characterized in that The groove portion (11) and / or the weak portion (12) are symmetrically distributed relative to the central axis of the battery, and the residual thickness h1 of the weak portion (12) satisfies: 0.05 mm ≤ h1 ≤ 0.27 mm; The groove portion (11) and / or the weak portion (12) are eccentrically distributed relative to the central axis of the battery, and the residual thickness h1 of the weak portion (12) satisfies: 0.04 mm ≤ h1 ≤ 0.25 mm.

9. The battery according to claim 1, characterized in that The bottom wall (14) is provided with a plurality of groove portions (11).

10. The battery according to claim 1, characterized in that The material of the shell (1) includes steel, and the residual thickness h1 of the weak portion (12) satisfies: 0.003 mm ≤ h1 ≤ 0.2 mm; The depth D of the groove portion (11) satisfies: 0.13 mm ≤ D ≤ 0.3 mm.

11. A battery pack, characterized in that: The battery according to any one of claims 1 to 10 further comprises a bus bar, wherein the bus bar comprises a terminal connecting portion.

12. The battery pack according to claim 11, characterized in that: The battery cover assembly (2) comprises a cover body and a pole; the busbar further comprises a cover body connection portion, wherein the pole connection portion is connected to the pole of the battery, and the cover body connection portion is connected to the cover body of another battery.

13. The battery pack according to claim 12, characterized in that: The battery comprises a cylindrical battery, the cover body is circular, and the diameter of the cover body is less than or equal to 60 mm. At this time, D·m satisfies: 0.12≤D·m≤60.

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