Battery monomer

Abstract

The invention relates to a battery cell. The shell is provided with an accommodating cavity and an end plate part for providing a part of the inner wall of the accommodating cavity; the electrode assembly is accommodated in the accommodating cavity, and a plurality of tabs are arranged on one side, facing the end plate part, of the electrode assembly; and the confluence plate is located between the electrode assembly and the end plate part and connected with the tabs and the end plate part, and the end plate part can generate deformation protruding towards the outside of the containing cavity under the action of air pressure in the containing cavity and drives the confluence plate to snap at least part of the tabs. Thus, when part of the tabs are snapped, the contact area between each tab and the confluence plate is reduced, the resistance is increased, and the generated heat is sharply increased, so that the temperature of the tabs which are not snapped reaches the melting point and the tabs are fused, and the circuit is cut off; and when all the tabs are snapped, the circuit is directly cut off.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and specifically to a battery cell. Background Art

[0002] Lithium-ion batteries have high energy density, long cycle life, good rate performance and safety, and are green and environmentally friendly. They are important energy products for modern electronic products and electric vehicles. Among them, the steel shell cylindrical lithium-ion batteries have unified models, high production automation, good battery consistency, and convenient combination design. They are the first choice in the fields of electronic products and electric vehicles and have been increasingly applied on a large scale. With the large-scale application, the requirements for the safety of batteries are also getting higher and higher.

[0003] A battery generally consists of multiple battery cells, and an explosion-proof valve is provided on each battery cell. When a battery cell undergoes thermal runaway due to an abnormality, a large amount of high-temperature flue gas and other substances will be generated. After the pressure reaches a certain value, the explosion-proof valve starts to relieve pressure. However, after the explosion-proof valve starts to relieve pressure, it cannot ensure that the circuit in the battery cell is cut off. If the circuit in the battery cell is not cut off, it will continue to heat up due to short circuit, resulting in heat spreading to other battery cells, and then triggering thermal runaway of the entire battery, seriously threatening personal safety and property safety. Summary of the Invention

[0004] Based on this, it is necessary to provide a battery cell that can ensure the circuit is cut off when the explosion-proof valve starts to relieve pressure in view of the above problems.

[0005] On the one hand, the present application provides a battery cell, including:

[0006] A housing having a receiving cavity and an end plate portion for providing a part of the inner wall of the receiving cavity;

[0007] An electrode assembly received in the receiving cavity and having a plurality of tabs on a side facing the end plate portion; and

[0008] A current collecting plate located between the electrode assembly and the end plate portion and connected to each of the tabs and the end plate portion. Under the action of the air pressure in the receiving cavity, the end plate portion can generate a deformation protruding out of the receiving cavity and drive the current collecting plate to break at least part of the tabs.

[0009] In some embodiments, the end plate portion has a first middle region and a first outer peripheral region surrounding the first middle region, and the current collecting plate is connected to the first middle region of the end plate portion;

[0010] The first peripheral region forms a first annular protrusion protruding from the side facing the electrode assembly to the side away from the electrode assembly, and the first annular protrusion is arranged around the first central region; and / or, the first peripheral region forms a second annular protrusion protruding from the side away from the electrode assembly to the side facing the electrode assembly, and the second annular protrusion is arranged around the first central region.

[0011] In some embodiments, the first peripheral region has the first annular protrusion and the second annular protrusion, at least one of the first annular protrusion and the second annular protrusion is provided as at least two, and the first annular protrusion and the second annular protrusion are alternately arranged along the radial direction of the end plate portion.

[0012] In some embodiments, each adjacent first annular protrusion and a second annular protrusion are connected to each other in the radial direction of the end plate portion.

[0013] In some embodiments, the current collecting plate has a second central region and an electrical connection region arranged around the second central region;

[0014] The second central region is connected to the first central region, and the electrical connection region is connected to each of the tabs.

[0015] In some embodiments, a boss is formed by the side of the first central region facing the electrode assembly protruding, and the boss is connected to the second central region; or

[0016] A boss is formed by the side of the second central region protruding away from the electrode assembly, and the boss is connected to the first central region.

[0017] In some embodiments, the current collecting plate further has a second peripheral region arranged around the electrical connection region and a first annular weak portion arranged between the electrical connection region and the second peripheral region. The second peripheral region is connected to the housing, and the first annular weak portion can be broken under the action of the pulling force generated when the end plate portion bulges and deforms out of the receiving cavity.

[0018] In some embodiments, the current collecting plate further has a second peripheral region arranged around the electrical connection region. The peripheral edge of the second peripheral region is connected to the housing. The second peripheral region forms a third annular protrusion protruding from the side facing the electrode assembly to the side away from the electrode assembly, and the third annular protrusion is arranged around the electrical connection region; and / or, the second peripheral region forms a fourth annular protrusion protruding from the side away from the electrode assembly to the side facing the electrode assembly, and the fourth annular protrusion is arranged around the electrical connection region.

[0019] In some of these embodiments, the first peripheral region of the end plate portion further has a second annular weak portion, and the second annular weak portion is arranged around the first central region;

[0020] When the air pressure in the accommodation cavity reaches a first preset value, the end plate portion bulges and deforms outward from the accommodation cavity and flattens the first annular protrusion and / or the second annular protrusion; when the air pressure in the accommodation cavity reaches a second preset value, the second annular weak portion ruptures; wherein, the second preset value is greater than the first preset value.

[0021] In some of these embodiments, the housing includes a housing body, a cover plate and a terminal post. The inner cavity of the housing body serves as the accommodation cavity, and one end of the housing body is a closed end, and the other end of the housing body is an open end. The cover plate covers the open end of the housing body;

[0022] The part of the housing body located at the closed end is the end plate portion. The terminal post is insulated and arranged on the end plate portion, and the end plate portion is connected to the bus bar through the terminal post; or

[0023] The cover plate serves as the end plate portion.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] During actual use of the above battery cell, if thermal runaway occurs due to an abnormality, the air pressure in the accommodation cavity of the housing increases. Under the action of this high air pressure, the end plate portion generates a deformation that bulges outward from the accommodation cavity (i.e., the end plate portion bulges outward from the accommodation cavity). Since the end plate portion is connected to the bus bar, the end plate portion pulls the bus bar to bulge and deform outward together, so that the pole ears fixed on the bus bar are partially or completely broken. When some of the pole ears are broken, the contact area between each pole ear and the bus bar decreases, the resistance increases, and the heat generation increases sharply, resulting in the temperature of the unbroken pole ears reaching the melting point and melting, thereby cutting off the circuit; when all the pole ears are broken, the circuit is directly cut off. That is to say, during thermal runaway, it can be ensured that each pole ear is disconnected from the bus bar, that is, the circuit in the battery cell is cut off, avoiding continuous temperature rise of the battery cell and causing heat to spread to other battery cells, greatly improving the safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a cross-sectional view of a battery cell in an embodiment of the present application;

[0027] Figure 2 is Figure 1 a partial enlarged view of the battery cell shown at A (when thermal runaway has not occurred);

[0028] Figure 3 is Figure 1Partial enlarged view of the battery cell at A (when thermal runaway occurs);

[0029] Figure 4 is Figure 1 Schematic structural diagram of the cover plate and bus bar of the battery cell shown;

[0030] Figure 5 Partial enlarged view at the open end of the battery cell in another embodiment;

[0031] Figure 6 is Figure 5 Partial enlarged view at the open end of the battery cell in the embodiment shown (when thermal runaway occurs);

[0032] Figure 7 Partial enlarged view at the open end of the battery cell in yet another embodiment;

[0033] Figure 8 is Figure 7 Partial enlarged view at the open end of the battery cell in the embodiment shown (when thermal runaway occurs). Detailed Description of the Invention

[0034] To make the above objects, features, and advantages of the present application more apparent and understandable, the following detailed description of the specific embodiments of the present application will be given with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0035] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present application.

[0036] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0037] In this application, unless otherwise clearly specified or limited, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] In this application, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature is at a higher level than the second feature in terms of horizontal height. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature is at a lower level than the second feature in terms of horizontal height.

[0039] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it may be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0040] An embodiment of this application provides an electrical device, and the electrical device uses the following battery or battery cell as its power source. Specifically, the electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; the electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact drill, a concrete vibrator, a planer, etc. The embodiments of this application do not impose special restrictions on the above electrical devices.

[0041] The battery includes a box body and battery cells, and the battery cells are accommodated in the box body. Among them, the box body is used to provide an accommodation space for the battery cells. The box body can adopt various structures and can also be of various shapes, such as a cuboid, etc. In the battery, there can be multiple battery cells, and the multiple battery cells can be connected in series, in parallel, or in a combined series-parallel connection. A combined series-parallel connection means that there are both series and parallel connections among the multiple battery cells. The multiple battery cells can be directly connected in series, in parallel, or in a combined series-parallel connection, and then the whole formed by the multiple battery cells is accommodated in the box body; of course, the battery can also be that multiple battery cells are first connected in series, in parallel, or in a combined series-parallel connection to form a battery module, and then multiple battery modules are connected in series, in parallel, or in a combined series-parallel connection to form a whole and are accommodated in the box body. The battery can also include other structures. For example, the battery can also include a busbar component for realizing the electrical connection between the multiple battery cells. Among them, each battery cell can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto.

[0042] The specific structure of the battery cell will be elaborated in detail below with reference to the accompanying drawings. Please refer to Figures 1 to 4 , in the embodiment of the present application, the battery cell includes a housing 10, an electrode assembly 20, and a busbar plate 30. The housing 10 has a receiving cavity 110 and an end plate portion 130 that provides a part of the inner wall of the receiving cavity 110. The electrode assembly 20 is received in the receiving cavity 110, and has a plurality of tabs (not shown in the figure) on the side facing the end plate portion 130. The busbar plate 30 is located between the electrode assembly 20 and the end plate portion 130 and is connected to each tab and the end plate portion 130. The end plate portion 130 can generate a deformation that bulges out of the receiving cavity 110 under the action of the air pressure in the receiving cavity 110, and drives the busbar plate 30 to break at least part of the tabs.

[0043] In the actual use process of the above battery cell, if thermal runaway occurs due to an abnormality, the air pressure in the receiving cavity 110 of the housing 10 increases. Under the action of this high air pressure, the end plate portion 130 generates a deformation that bulges out of the receiving cavity 110 (that is, the end plate portion 130 bulges out of the receiving cavity 110). Since the end plate portion 130 is connected to the busbar plate 30, the end plate portion 130 pulls the busbar plate 30 to bulge out and deform together, so that the tabs fixed on the busbar plate 30 are partially or completely broken. When some of the tabs are broken, the contact area between each tab and the busbar plate 30 decreases, the resistance increases, and the heat generation increases sharply, resulting in the temperature of the unbroken tabs reaching the melting point and melting, realizing the cutting of the circuit; when all the tabs are broken, the circuit is directly cut off. That is to say, when thermal runaway occurs, it can be ensured that each tab is disconnected from the busbar plate 30, that is, the circuit in the battery cell is cut off, avoiding the continuous temperature rise of the battery cell and causing heat to spread to other battery cells, greatly improving the safety of the battery.

[0044] Specifically, the outer shell 10 includes a housing 11, a cover plate 13, and a terminal post 40. The inner cavity of the housing 11 serves as the above-mentioned receiving cavity 110. One end of the housing 11 is a closed end 112, and the other end of the housing 11 is an open end 114. The cover plate 13 is welded and fixed to the open end 114 of the housing 11 and seals the open end 114 of the housing 11, thereby enclosing the electrode assembly 20 in the receiving cavity 110 of the housing 11. The terminal post 40 is insulatingly installed at the closed end 112 of the housing 11. Both the end of the electrode assembly 20 facing the closed end 112 and the end facing the open end 114 have electrode tabs, and the electrode tabs at both ends of the electrode assembly 20 have opposite polarities. For example, the electrode tab of the electrode assembly 20 facing the open end 114 is the positive electrode tab, and the electrode tab facing the closed end 112 is the negative electrode tab. Or, the electrode tab of the electrode assembly 20 facing the open end 114 is the negative electrode tab, and the electrode tab facing the closed end 112 is the positive electrode tab. The terminal post 40 is electrically connected to the electrode tab of the electrode assembly 20 facing the closed end 112, such that the terminal post 40 serves as one electrode terminal of the battery cell. The cover plate 13 is electrically connected to the electrode tab of the electrode assembly 20 facing the open end 114, such that the cover plate 13 or the housing 11 serves as the other electrode terminal of the battery cell, and the two electrode terminals jointly achieve the input and output of electrical energy.

[0045] In some embodiments, the end plate portion 130 may be the cover plate 13, and the cover plate 13 is connected to the electrode tab of the electrode assembly 20 facing the cover plate 13 through a bus bar 30. During actual use, if thermal runaway occurs due to an abnormality, the air pressure in the receiving cavity 110 increases. Under the action of this high air pressure, the cover plate 13 deforms and bulges outwards from the receiving cavity 110 (i.e., the cover plate 13 bulges outwards from the receiving cavity 110). Since the cover plate 13 is connected to the bus bar 30, the cover plate 13 pulls the bus bar 30 to bulge outwards together, so that the electrode tab fixed on the bus bar 30 is partially or completely broken.

[0046] It should be noted that the end plate portion 130 is not limited to being the cover plate 13. In some other embodiments, the end plate portion 130 may also be the part of the housing 11 at the closed end 112. The terminal post 40 at the closed end 112 is connected to the electrode tab of the electrode assembly 20 facing the closed end 112 through a bus bar. During actual use, if thermal runaway occurs due to an abnormality, the air pressure in the receiving cavity 110 increases. Under the action of this high air pressure, the closed end 112 of the housing 11 deforms and bulges outwards from the receiving cavity 110 (i.e., the closed end 112 of the housing 11 bulges outwards from the receiving cavity 110). Since the closed end 112 of the housing 11 is connected to the bus bar 30, the closed end 112 of the housing 11 pulls the bus bar 30 to bulge outwards together, so that the electrode tab fixed on the bus bar 30 is partially or completely broken.

[0047] For ease of understanding, the following description will be given taking the end plate portion 130 as the cover plate 13 as an example:

[0048] In some embodiments of the present application, the cover plate 13 has a first central region 131 and a first peripheral region 135 surrounding the first central region 131. The busbar 30 is connected to the first central region 131 of the cover plate 13. The first peripheral region 135 protrudes from the side facing the electrode assembly 20 to the side facing away from the electrode assembly 20 to form a first annular protrusion a1, and the first annular protrusion a1 is arranged around the first central region 131. The first peripheral region 135 protrudes from the side facing away from the electrode assembly 20 to the side facing the electrode assembly 20 to form a second annular protrusion a2, and the second annular protrusion a2 is arranged around the first central region 131. In this way, by arranging the first annular protrusion a1 and the second annular protrusion a2 in the first outer region 135 of the cover plate 13, the first outer region 135 is made wavy, which is beneficial to improving the deformation ability of the cover plate 13 on the one hand, ensuring that when the air pressure in the receiving cavity 110 reaches the preset pressure, the cover plate 13 can be deformed to bulge out of the receiving cavity 110; on the other hand, it is beneficial to increase the maximum deformation amount of the cover plate 13 to bulge out of the receiving cavity 110, thereby increasing the movement amplitude of pulling the busbar 30, and then pulling off as many pole ears as possible, ensuring that the circuit inside the battery cell is cut off in time.

[0049] It should be noted that when the cover plate 13 bulges outward from the receiving cavity 110, the movement amplitude of the middle part of the cover plate 13 (i.e., the first middle area 131) is the largest. Therefore, the busbar 30 is connected to the first middle area 131 of the cover plate 13 to increase the movement amplitude of the busbar 30 as much as possible, thereby breaking as many pole ears as possible, ensuring that the circuit inside the battery cell is cut off in time.

[0050] It should also be noted that the first peripheral area 135 of the cover plate 13 is not limited to having both the first annular protrusion a1 and the second annular protrusion a2. In other embodiments, the first peripheral area 135 of the cover plate 13 may only have the first annular protrusion a1, without the second annular protrusion a2; of course, the first peripheral area 135 of the cover plate 13 may also only have the second annular protrusion a2, without the first annular protrusion a1, which is not particularly limited here.

[0051] Specifically in this embodiment, the first peripheral region 135 has a first annular protrusion a1 and a second annular protrusion a2. At least one of the first annular protrusion a1 and the second annular protrusion a2 is provided with at least two, and the first annular protrusion a1 and the second annular protrusion a2 are alternately arranged along the radial direction of the cover plate 13. Optionally, each adjacent first annular protrusion a1 and a second annular protrusion a2 are connected to each other in the radial direction of the cover plate 13, so that the first peripheral region 135 of the cover plate 13 forms a wavy shape, which is convenient for stamping on the one hand, and on the other hand is beneficial to straightening each first annular protrusion a1 and each second annular protrusion a2 quickly when thermal runaway occurs. Of course, in other embodiments, each first annular protrusion a1 and each second annular protrusion a2 may also adopt other arrangement methods, for example, the adjacent first annular protrusion a1 and the second annular protrusion a2 are not connected to each other, but are spaced apart by a certain distance.

[0052] Further, in the embodiment where each adjacent first annular protrusion a1 and a second annular protrusion a2 are connected to each other in the radial direction of the cover plate 13, the sum R of the ring diameters of the orthographic projections of each first annular protrusion a1 and each second annular protrusion a2 on the plane where the cover plate 13 is located is 2 mm to 5 mm. It should be noted that if the value of R is too large, the deformation ability of the cover plate 13 is too large and the strength of the cover plate 13 is too low, so the cover plate 13 is easily damaged during use. In this embodiment, setting the value of R between 2 mm and 5 mm can ensure that when the air pressure in the receiving cavity 110 reaches the preset value while the strength of the cover plate 13 meets the requirements, the cover plate 13 can bulge and deform outward from the receiving cavity 110 in time, so as to straighten each first annular protrusion a1 and each second annular protrusion a2.

[0053] It can be understood that the first annular protrusion a1 refers to the part that protrudes from the plane where the cover plate 13 is located on the side of the cover plate 13 facing away from the electrode assembly 20, and the second annular protrusion a2 refers to the part that protrudes from the plane where the cover plate 13 is located on the side of the cover plate 13 facing the electrode assembly 20. Therefore, the part of the cover plate 13 between the adjacent first annular protrusion a1 and the second annular protrusion a2 and located in the plane where the cover plate 13 is located forms the boundary between the adjacent first annular protrusion a1 and the second annular protrusion a2.

[0054] Specifically, R can be 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm or 5 mm, etc., including but not limited to the listed values, and other values within the above range are still applicable, and no special limitation is made here.

[0055] Further, the number of the first annular protrusions a1 is N1, the number of the second annular protrusions a2 is N2, and both N1 and N2 are positive integers less than or equal to 3. That is to say, the numbers of the first annular protrusions a1 and the second annular protrusions a2 are both less than or equal to 3. It should be noted that when the numbers of the first annular protrusions a1 and the second annular protrusions a2 are too large in a limited area, each of the first annular protrusions a1 and the second annular protrusions a2 will play a role similar to that of a reinforcing rib, resulting in a reduction in the deformation ability of the cover plate 13. In this embodiment, the numbers of the first annular protrusions a1 and the second annular protrusions a2 are both set to be less than or equal to 3, which is beneficial to ensuring that when the air pressure in the accommodation cavity 110 reaches a preset value, the cover plate 13 can bulge and deform outwards in time, so as to straighten each of the first annular protrusions a1 and each of the second annular protrusions a2.

[0056] Optionally, the number N1 of the first annular protrusions a1 is 2, the number N2 of the second annular protrusions a2 is 1, and one second annular protrusion a2 is arranged between the two first annular protrusions a1.

[0057] In the embodiment of the present application, the bus bar 30 has a second middle area 31 and an electrical connection area 33 arranged around the second middle area 31. The second middle area 31 is connected to the first middle area 131, and the electrical connection area 33 is connected to each tab. In this way, the middle part (i.e., the second middle area 31) of the bus bar 30 is connected to the middle part (i.e., the first middle area 131) of the cover plate 13. Since the middle part (i.e., the first middle area 131) of the cover plate 13 bulges outwards the most when the cover plate 13 bulges and deforms outwards under the action of the air pressure in the accommodation cavity 110, the middle part (i.e., the first middle area 131) of the cover plate 13 pulls the bus bar 30 to move the most, so as to achieve the purpose of breaking as many tabs as possible.

[0058] It should be noted that the second middle area 31 of the bus bar 30 and the first middle area 131 of the cover plate 13 can be connected by welding, and the electrical connection area 33 of the bus bar 30 and each tab can be connected by welding, so as to avoid the mutual influence of the welding of the bus bar 30 with the cover plate 13 and the tabs respectively, which is beneficial to improving the welding quality.

[0059] In some embodiments, the second middle area 31 of the bus bar 30 bulges towards the side away from the electrode assembly 20 to form a boss 32, and the boss 32 is attached to the first middle area 131 of the cover plate 13 and fixed by welding. In this way, the setting of the boss 32 is beneficial to improving the welding quality and reducing the welding difficulty.

[0060] It can be understood that since the welded and fixed part of the boss 32 and the first middle area 131 of the cover plate 13 will not deform, when the welding and fixing area of the boss 32 and the first middle area 131 of the cover plate 13 is too large, the deformable area of the cover plate 13 is too small, resulting in a reduced movement amplitude of pulling the bus bar 30, and further resulting in a reduced number of tab ears that can be broken. Further, the diameter D of the boss 32 ≤ 10 mm, so as to avoid too large a welding and fixing area of the boss 32 and the first middle area 131 of the cover plate 13, and further ensure that enough tab ears can be broken when the cover plate 13 bulges and deforms outward.

[0061] It should be noted that the boss 32 is not limited to being formed on the bus bar 30. In some other embodiments, the boss 32 can also be formed on the cover plate 13. That is to say, the first middle area 131 of the cover plate 13 protrudes toward the electrode assembly 20 to form the boss 32, and the boss 32 is attached to and welded and fixed with the second middle area 31 of the bus bar 30.

[0062] Please refer to Figure 5 and Figure 6 , in some embodiments, the first peripheral area 135 of the cover plate 13 further has a second annular weak part 137. The second annular weak part 137 is arranged around the first middle area 131. When the battery cell undergoes thermal runaway, the air pressure in the accommodation cavity 110 of the housing 10 rises rapidly. When the air pressure in the accommodation cavity 110 reaches the first preset value, the cover plate 13 bulges and deforms outward from the accommodation cavity 110 and flattens the first annular protrusion a1 and / or the second annular protrusion a2. When the air pressure in the accommodation cavity 110 continues to rise to the second preset value (the second preset value is larger than the first preset value), the second annular weak part 137 ruptures, thereby realizing pressure relief and preventing the air pressure in the accommodation cavity 110 of the housing 10 from continuing to rise and causing an explosion.

[0063] Further, the second annular weak part 137 can be formed by machining a notch groove on the cover plate 13 or by opening a hole on the cover plate 13, as long as the strength of the cover plate 13 can be locally weakened so that the second annular weak part 137 can rupture in time when the air pressure in the accommodation cavity 110 of the housing 10 reaches the second preset value, and no limitation is made here. Optionally, the first preset value can be 0.9 Mpa - 1.4 Mpa. The second preset value can be 1.2 Mpa - 1.6 Mpa.

[0064] Specifically, the first preset value can be 0.9 Mpa, 1.0 Mpa, 1.1 Mpa, 1.2 Mpa, 1.3 Mpa, 1.4 Mpa, etc., including but not limited to the listed values. Other values within the above range are still applicable and are not specifically limited herein. The second preset value can be 1.2 Mpa, 1.3 Mpa, 1.4 Mpa, 1.5 Mpa, 1.6 Mpa, etc., including but not limited to the listed values. Other values within the above range are still applicable and are not specifically limited herein.

[0065] Further, each first annular protrusion a1 and each second annular protrusion a2 are arranged around the second annular weak part 137, that is to say, each first annular protrusion a1 and each second annular protrusion a2 are located outside the second annular weak part 137. Of course, in other embodiments, each first annular protrusion a1 and each second annular protrusion a2 can also be arranged inside the second annular weak part 137, which is not specifically limited herein.

[0066] Each first annular protrusion a1 and each second annular protrusion a2 are arranged at intervals from the second annular weak part 137 to avoid affecting the valve opening consistency of the second annular weak part 137.

[0067] When the second annular weak part 137 is formed by machining a notch groove on the cover plate 13, the notch groove can be located on the inner surface or the outer surface of the cover plate 13. When located on the inner surface, the influence of external factors on the notch groove can be avoided, such as being scratched by foreign objects.

[0068] Please refer to Figure 5 and Figure 6 , in some embodiments, the busbar 30 further has a second peripheral area 35 disposed around the electrical connection area 33 and a first annular weak part 34 disposed between the electrical connection area 33 and the second peripheral area 35. The second peripheral area 35 is connected to the inner wall of the housing 11, and the first annular weak part 34 can be broken under the tensile force generated when the cover plate 13 bulges and deforms outward from the accommodation cavity 110. Thus, if thermal runaway occurs due to an abnormality, the air pressure in the accommodation cavity 110 of the outer shell 10 increases. Under the action of this high air pressure, the cover plate 13 generates a deformation of bulging outward from the accommodation cavity 110 (that is, the cover plate 13 bulges outward from the accommodation cavity 110). Since the cover plate 13 is connected to the busbar 30, the first annular weak part 34 is broken under the tensile force. At this time, the cover plate 13 pulls the second middle area 31 and the electrical connection area 33 of the busbar 30 to bulge and deform outward together, so that the tabs fixed on the electrical connection area 33 of the busbar 30 are partially or completely broken.

[0069] Furthermore, the peripheral outer edge of the second peripheral region 35 is turned over to form an annular flange, and the annular flange is attached to and welded to the inner wall of the housing 11, thereby realizing the fixed connection and electrical connection between the current collecting plate 30 and the housing 11.

[0070] It should be noted that in this embodiment, since the second peripheral region 35 of the current collecting plate 30 is connected to the inner wall of the housing 11, for example, the second peripheral region 35 of the current collecting plate 30 is fixedly welded to the inner wall of the housing 11, so that the tab of the electrode assembly 20 can be electrically connected to the housing 11 through the current collecting plate 30. Therefore, the boss 32 of the current collecting plate 30 only needs to be fixedly connected to the cover plate 13 and does not need to be electrically connected to the cover plate 13. Therefore, in the embodiment where the second peripheral region 35 of the current collecting plate 30 is connected to the housing 11, the boss 32 of the current collecting plate 30 can also be fixedly bonded to the first middle region 131 of the cover plate 13 with an adhesive, as long as the fixed connection between the boss 32 of the current collecting plate 30 and the first middle region 131 of the cover plate 13 can be realized, which is not limited herein.

[0071] It should also be noted that the setting of the first annular weak part 34 can, on the one hand, rupture under the tensile force provided by the cover plate 13, so that the electrical connection region 33 and the second peripheral region 35 of the current collecting plate 30 are separated from each other, thereby cutting off the electrical connection between the current collecting plate 30 and the housing 11; on the other hand, after the first annular weak part 34 ruptures, the second middle region 31 and the electrical connection region 33 of the current collecting plate 30 are separated from the second peripheral region 35, so that the second middle region 31 and the electrical connection region 33 of the current collecting plate 30 can move outward together with the cover plate 13 to ensure that a sufficient number of tabs are broken.

[0072] Furthermore, the first annular weak part 34 can be formed by machining a notch groove on the current collecting plate 30 or by punching holes, as long as the strength of the current collecting plate 30 can be locally weakened so that it can rupture under the tensile force of the cover plate 13 in case of an abnormality, which is not limited herein.

[0073] Please refer to Figure 7 and Figure 8As shown, in some other embodiments, the bus bar 30 further has a second peripheral region 35 disposed around the electrical connection region 33. The peripheral edge of the second peripheral region 35 is connected to the inner wall of the housing 11. The second peripheral region 35 protrudes from the side facing the electrode assembly 20 to the side away from the electrode assembly 20 to form a third annular protrusion a3, which is disposed around the electrical connection region 33. The second peripheral region 35 protrudes from the side away from the electrode assembly 20 to the side facing the electrode assembly 20 to form a fourth annular protrusion a4, which is disposed around the electrical connection region 33. Thus, if thermal runaway occurs due to an abnormality, the air pressure in the accommodation cavity 110 of the housing 11 increases. Under the action of this high air pressure, the cover plate 13 deforms to protrude out of the accommodation cavity 110 (i.e., the cover plate 13 bulges out of the accommodation cavity 110). Since the cover plate 13 is connected to the bus bar 30, the cover plate 13 pulls the second middle region 31 and the electrical connection region 33 of the bus bar 30 to protrude and deform outward together. At the same time, the third annular protrusion a3 and the fourth annular protrusion a4 are straightened, so that the tabs fixed on the electrical connection region 33 of the bus bar 30 are partially or completely broken off.

[0074] It should be noted that the setting of the third annular protrusion a3 and the fourth annular protrusion a4 enables the third annular protrusion a3 and the fourth annular protrusion a4 to be straightened when the cover plate 13 pulls the bus bar 30, thereby greatly increasing the amplitude of the second middle region 31 and the electrical connection region 33 of the bus bar 30 moving outward together with the cover plate 13, ensuring that the number of broken tabs is sufficient.

[0075] It should also be noted that the second peripheral region 35 of the bus bar 30 is not limited to having both the third annular protrusion a3 and the fourth annular protrusion a4. In some other embodiments, the second peripheral region 35 of the bus bar 30 may only have the third annular protrusion a3 and not have the fourth annular protrusion a4; of course, the second peripheral region 35 of the bus bar 30 may also only have the fourth annular protrusion a4 and not have the third annular protrusion a3, and no special limitation is made here.

[0076] Specifically in this embodiment, the second peripheral region 35 of the busbar 30 has a third annular protrusion a3 and a fourth annular protrusion a4. At least one of the third annular protrusion a3 and the fourth annular protrusion a4 is provided with at least two, and the third annular protrusion a3 and the fourth annular protrusion a4 are alternately arranged along the radial direction of the busbar 30. Optionally, each adjacent third annular protrusion a3 and a fourth annular protrusion a4 are connected to each other in the radial direction of the busbar 30, so that the second peripheral region 35 of the busbar 30 forms a wavy shape, which is convenient for stamping on the one hand, and on the other hand is beneficial to the rapid straightening of each third annular protrusion a3 and each fourth annular protrusion a4 during thermal runaway. Of course, in other embodiments, each third annular protrusion a3 and each fourth annular protrusion a4 can also adopt other arrangement methods, for example, adjacent third annular protrusions a3 and fourth annular protrusions a4 are not connected to each other, but are spaced apart by a certain distance.

[0077] Further, the number of the third annular protrusions a3 is N3, the number of the fourth annular protrusions a4 is N4, and both N3 and N4 are positive integers less than or equal to 3. That is to say, the number of the third annular protrusions a3 and the fourth annular protrusions a4 are both less than or equal to 3. It should be noted that when the number of the third annular protrusions a3 and the fourth annular protrusions a4 is too large in a limited area, each third annular protrusion a3 and each fourth annular protrusion a4 will play a role similar to that of a reinforcing rib, resulting in a reduction in the deformation ability of the busbar 30. In this embodiment, the number of the third annular protrusions a3 and the fourth annular protrusions a4 are both set to be less than or equal to 3, which is beneficial to ensuring that each third annular protrusion a3 and each fourth annular protrusion a4 can be straightened in time.

[0078] Optionally, the number N3 of the third annular protrusions a3 is 2, the number N4 of the fourth annular protrusions a4 is 1, and one fourth annular protrusion a4 is arranged between two third annular protrusions a3.

[0079] It should also be noted that in some embodiments, the third annular protrusion a3 and the fourth annular protrusion a4 are provided on the busbar 30, and the first annular weak part 34 is not provided. In other embodiments, the first annular weak part 34 is provided on the busbar 30, and the third annular protrusion a3 and the fourth annular protrusion a4 are not provided. In still other embodiments, both the third annular protrusion a3 and the fourth annular protrusion a4 and the first annular weak part 34 are provided on the busbar 30, as long as enough tabs can be broken under the pulling action of the cover plate 13, and no special limitation is made here.

[0080] In some embodiments, the elasticity of the material itself can also be used to ensure that the cover plate 13 deforms to bulge outwards from the receiving cavity 110 under the action of high air pressure (i.e., the cover plate 13 bulges outwards from the receiving cavity 110). For example, the first peripheral region 135 can be made of a material with strong deformation ability.

[0081] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0082] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A battery cell, characterized in that: include: A housing (10) having a receiving cavity (110) and an end plate portion (130) for providing a portion of the inner wall of the receiving cavity (110); An electrode assembly (20) is accommodated in the accommodation cavity (110) and has a plurality of pole ears on a side facing the end plate portion (130); and The bus plate (30) is located between the electrode assembly (20) and the end plate portion (130), and is connected to each of the pole lugs and the end plate portion (130). Under the action of the air pressure in the receiving cavity (110), the end plate portion (130) can be deformed to bulge out of the receiving cavity (110), and drive the bus plate (30) to pull off at least part of the pole lugs.

2. The battery cell according to claim 1, characterized in that: The end plate portion (130) has a first middle region (131) and a first peripheral region (135) surrounding the first middle region (131), and the busbar (30) is connected to the first middle region (131) of the end plate portion (130); The first peripheral region (135) protrudes from a side facing the electrode assembly (20) to a side facing away from the electrode assembly (20) to form a first annular protrusion (a1), and the first annular protrusion (a1) is arranged around the first central region (131); and / or the first peripheral region (135) protrudes from a side facing away from the electrode assembly (20) to a side facing the electrode assembly (20) to form a second annular protrusion (a2), and the second annular protrusion (a2) is arranged around the first central region (131).

3. The battery cell according to claim 2, characterized in that: The first peripheral area (135) has the first annular protrusion (a1) and the second annular protrusion (a2), at least one of the first annular protrusion (a1) and the second annular protrusion (a2) is set to at least two, and the first annular protrusion (a1) and the second annular protrusion (a2) are alternately arranged along the radial direction of the end plate portion (130).

4. The battery cell according to claim 3, characterized in that: Each adjacent first annular protrusion (a1) and each adjacent second annular protrusion (a2) are connected to each other in the radial direction of the end plate portion (130).

5. The battery cell according to claim 2, characterized in that: The busbar (30) comprises a second middle region (31) and an electrical connection region (33) arranged around the second middle region (31); The second middle region (31) is connected to the first middle region (131), and the electrical connection region (33) is connected to each of the tabs.

6. The battery cell according to claim 5, characterized in that: The first middle region (131) protrudes toward one side of the electrode assembly (20) to form a boss (32), and the boss (32) is connected to the second middle region (31); or The second middle region (31) protrudes toward a side away from the electrode assembly (20) to form a boss (32), and the boss (32) is connected to the first middle region (131).

7. The battery cell according to claim 5, characterized in that: The busbar (30) further comprises a second peripheral region (35) arranged around the electrical connection region (33) and a first annular weak portion (34) arranged between the electrical connection region (33) and the second peripheral region (35), wherein the second peripheral region (35) is connected to the housing (10), and the first annular weak portion (34) is capable of being broken under the action of a tensile force generated when the end plate portion (130) is deformed to bulge out of the accommodating cavity (110).

8. The battery cell according to claim 5, characterized in that: The busbar (30) further comprises a second peripheral region (35) arranged around the electrical connection region (33), the peripheral edge of the second peripheral region (35) being connected to the housing (10), the second peripheral region (35) protruding from a side facing the electrode assembly (20) to a side facing away from the electrode assembly (20) to form a third annular protrusion (a3), and the third annular protrusion (a3) ​​is arranged around the electrical connection region (33); and / or the second peripheral region (35) protruding from a side facing away from the electrode assembly (20) to a side facing the electrode assembly (20) to form a fourth annular protrusion (a4), and the fourth annular protrusion (a4) is arranged around the electrical connection region (33).

9. The battery cell according to claim 2, characterized in that: The first peripheral area (135) of the end plate portion (130) further has a second annular weak portion (137), and the second annular weak portion (137) is arranged around the first middle area (131); When the air pressure in the receiving cavity (110) reaches a first preset value, the end plate portion (130) bulges outward from the receiving cavity (110) and deforms to flatten the first annular protrusion (a1) and / or the second annular protrusion (a2); when the air pressure in the receiving cavity (110) reaches a second preset value, the second annular weak portion (137) ruptures; wherein the second preset value is greater than the first preset value.

10. The battery cell according to claim 1, characterized in that: The housing (10) comprises a shell (11), a cover plate (13) and a pole (40); the inner cavity of the shell (11) serves as the receiving cavity (110); one end of the shell (11) is a closed end (112); the other end of the shell (11) is an open end (114); and the cover plate (13) covers the open end (114) of the shell (11); The portion of the housing (11) located at the closed end (112) is the end plate portion (130), the pole (40) is insulated and arranged on the end plate portion (130), and the end plate portion (130) is connected to the busbar (30) via the pole (40); or The cover plate (13) serves as the end plate portion (130).

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