Cover plate assembly and single battery

Abstract

The invention discloses a cover plate assembly and a single battery, and belongs to the technical field of batteries, the cover plate assembly comprises: a cover plate body having an explosion-proof hole; the explosion-proof valve covers and seals the explosion-proof hole, the explosion-proof valve comprises a connecting part, a first thinning part and a second thinning part, the first thinning part is connected to the second thinning part in a surrounding mode, and a nick is arranged at the connecting position of the first thinning part and the second thinning part. By connecting the reinforcing sheet with the anti-explosion valve, when the battery is normally used, the strength and the anti-deformation capability of the anti-explosion valve can be improved, and when the battery is in thermal runaway, the reinforcing sheet can be softened, so that the anti-explosion valve can be conveniently opened in time to release pressure, and the safety of the battery is ensured. Meanwhile, when the projected area S1 of the reinforcing sheet on the cover plate body in the thickness direction and the area S2 of the second thinning part meet the condition that S1 / S2 is larger than or equal to 1.2 and smaller than or equal to 3, the reinforcing effect of the reinforcing sheet on the anti-explosion valve can be further guaranteed, and the strength of the battery in normal use is guaranteed.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and in particular relates to a cover plate assembly and a single cell. Background Art

[0002] The function of the explosion-proof valve is to open when the internal pressure of the battery exceeds the safety limit, allowing gas to be released from the battery to reduce the internal pressure. This can effectively prevent the battery from exploding and protect the safety of the surrounding environment and users. However, during the use of the battery, the explosion-proof valve on it may be deformed or even ruptured by external forces, affecting the normal use of the explosion-proof valve. Summary of the invention

[0003] Purpose of the invention: An embodiment of the present application provides a cover plate assembly, aiming to overcome the technical problem that the explosion-proof valve on the battery may be deformed or even ruptured due to external force during use; another purpose of the embodiment of the present application is to provide a single cell battery.

[0004] Technical solution: A cover plate assembly described in an embodiment of the present application includes:

[0005] The cover body has explosion-proof holes;

[0006] An explosion-proof valve, covering the explosion-proof hole, the explosion-proof valve comprises a connecting portion, a first thinned portion and a second thinned portion, the first thinned portion is connected to the second thinned portion in a surrounding manner, a notch is provided at the connection between the first thinned portion and the second thinned portion, the connecting portion is connected to the first thinned portion in a surrounding manner, and is connected to the cover plate body;

[0007] A reinforcing sheet, located on a side of the explosion-proof valve facing the electrode assembly and connected to the explosion-proof valve, along the thickness direction of the cover plate body, the outer contour of the reinforcing sheet projected on the cover plate body surrounds the explosion-proof hole, and the outer contour of the explosion-proof valve projected on the cover plate body surrounds the outer contour of the reinforcing sheet projected on the cover plate body;

[0008] The cover plate assembly satisfies: 1.2≤S1 / S2≤3;

[0009] Wherein, S1 is the projection area of ​​the reinforcing sheet on the cover plate body along the thickness direction, and S2 is the area of ​​the second thinned portion.

[0010] In some embodiments, along the thickness direction of the cover plate body, the outer contour of the orthographic projection of the explosion-proof hole on the explosion-proof valve surrounds the notch.

[0011] In some embodiments, the thickness of the second thinned portion is a, and the thickness of the explosion-proof valve at the notch position is b, satisfying: 3≤a / b≤50.

[0012] In some embodiments, the reinforcing sheet is fitted with the explosion-proof valve, and along the thickness direction of the cover plate body, the outer contour of the orthographic projection of the reinforcing sheet on the explosion-proof valve surrounds the notch and satisfies: 1mm≤A≤5mm;

[0013] Among them, A is the distance from the outer contour of the projection of the notch on the reinforcing sheet along the thickness direction to the outer contour of the reinforcing sheet.

[0014] In some embodiments, when the cover plate assembly is used for a ternary system battery, the critical pressure value at which both the explosion-proof valve and the reinforcement sheet are ruptured is PA, and when the temperature of the explosion-proof valve is lower than a preset temperature, the following conditions are satisfied: PA>1.1Mpa; when the temperature of the explosion-proof valve is higher than a preset temperature, the following conditions are satisfied: 0.5MPa≤PA≤0.7Mpa;

[0015] When the cover plate assembly is used for an iron-lithium battery, the critical pressure value for the rupture of both the explosion-proof valve and the reinforcement plate is PB, and when the temperature of the explosion-proof valve is lower than a preset temperature, PB>0.8Mpa is satisfied; when the temperature of the explosion-proof valve is higher than a preset temperature, 0.2MPa≤PB≤0.4Mpa is satisfied.

[0016] In some embodiments, the notch is disposed around the second thinned portion and is located on a side of the explosion-proof valve away from the reinforcing sheet.

[0017] In some embodiments, the softening temperature of the reinforcing sheet is T, satisfying: 65°<T≤110°.

[0018] In some embodiments, the thickness of the reinforcing sheet is t, satisfying: 0.5 mm < t ≤ 1 mm.

[0019] In some embodiments, the reinforcing sheet is made of polypropylene material or polyolefin material.

[0020] A single battery, comprising:

[0021] A housing having a receiving cavity;

[0022] An electrode assembly is disposed in the accommodating cavity;

[0023] The cover plate assembly described in any one of the above is configured to cover the accommodating cavity and be connected to the shell.

[0024] Beneficial effect: The cover assembly of the embodiment of the present application includes: a cover body, which has an explosion-proof hole; an explosion-proof valve, which covers the explosion-proof hole, the explosion-proof valve includes a connecting portion, a first thinning portion and a second thinning portion, the first thinning portion is connected to the second thinning portion in a surrounding manner, and a notch is provided at the connection between the first thinning portion and the second thinning portion, the connecting portion is connected to the first thinning portion in a surrounding manner, and is connected to the cover body; a reinforcing sheet, which is located on the side of the explosion-proof valve facing the electrode assembly and is connected to the explosion-proof valve, along the thickness direction of the cover body, the outer contour of the reinforcing sheet projected on the cover body surrounds the explosion-proof hole, and the outer contour of the explosion-proof valve projected on the cover body surrounds the outer contour of the reinforcing sheet projected on the cover body; the cover assembly satisfies: 1.2≤S1 / S2≤3; wherein S1 is the projection area of ​​the reinforcing sheet on the cover body along the thickness direction, and S2 is the area of ​​the second thinning portion. By connecting the reinforcing sheet to the explosion-proof valve, the strength of the explosion-proof valve can be improved and its anti-deformation ability can be improved when the battery is in normal use. When the battery has thermal runaway, the reinforcing sheet can soften, thereby facilitating the timely opening of the explosion-proof valve to release pressure and ensure the safety of the battery. At the same time, when the projection area S1 of the reinforcing sheet on the cover body along the thickness direction and the area S2 of the second thinning portion satisfy: 1.2≤S1 / S2≤3, the reinforcing effect of the reinforcing sheet on the explosion-proof valve can be further guaranteed, and the strength of the battery in normal use can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 It is a front cross-sectional view of the cover plate assembly of the embodiment of the present application;

[0027] Figure 2 This is a three-dimensional diagram of an explosion-proof valve according to an embodiment of the present application;

[0028] Figure 3 This is a cross-sectional view of the connection between the cover plate body and the explosion-proof valve in the embodiment of the present application;

[0029] Figure 4 For the embodiment of this application Figure 3 A partial enlarged view of the middle M area;

[0030] Figure 5 This is a schematic diagram comparing the outer contours of the notches, explosion-proof holes, reinforcement sheets, and explosion-proof valves in the embodiment of the present application;

[0031] Figure numerals: 10 - cover body; 11 - explosion-proof hole; 20 - explosion-proof valve; 21 - connecting portion; 22 - first thinning portion; 23 - second thinning portion; 24 - notch; 30 - reinforcement sheet; X - thickness direction. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0033] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "plurality" means two or more, and at least one means one, two or more, unless otherwise clearly and specifically defined.

[0034] The battery has an explosion-proof valve, which automatically opens when the pressure inside the battery exceeds the preset opening pressure of the explosion-proof valve, thereby releasing the pressure inside the battery and ensuring the safe operation of the battery. However, during the manufacturing process or normal use of the battery, the explosion-proof valve may be squeezed, deformed, or the electrolyte may impact the explosion-proof valve, causing the explosion-proof valve to open abnormally or rupture, affecting the normal use of the explosion-proof valve.

[0035] In view of this, an embodiment of the present application provides a cover plate assembly to overcome at least one of the above-mentioned technical problems.

[0036] See also Figure 1 , Figure 2 , Figure 3 and Figure 5 In an embodiment of the present application, the cover plate assembly includes a cover plate body 10 , an explosion-proof valve 20 and a reinforcement sheet 30 .

[0037] The cover body 10 has an explosion-proof hole 11, which is arranged along the thickness direction of the cover body 10, and can connect the space inside the battery shell with the external environment. The explosion-proof valve 20 covers the explosion-proof hole 11, and the explosion-proof valve 20 includes a connecting portion 21, a first thinning portion 22 and a second thinning portion 23. The first thinning portion 22 is connected to the second thinning portion 23 in a circumferential manner, and a notch 24 is provided at the connection between the first thinning portion 22 and the second thinning portion 23. The connecting portion 21 is connected to the first thinning portion 22 in a circumferential manner and is connected to the cover body 10. The explosion-proof valve 20 can be arranged inside the explosion-proof hole 11 or outside the explosion-proof hole 11, as long as it can cover the explosion-proof hole 11. The explosion-proof valve 20 is connected to the cover body 10 through the connecting portion 21 thereon, so that the explosion-proof valve 20 can be fixed as a whole on the cover body 10. A first thinning portion 22 and a second thinning portion 23 are provided on the explosion-proof valve 20. The dimensions of both in the thickness direction of the cover body 10 are smaller than the dimension of the connecting portion 21 in the thickness direction. At the same time, a notch 24 is provided at the connection between the first thinning portion 22 and the second thinning portion 23, so that the thickness dimension of the connection between the first thinning portion 22 and the second thinning portion 23 is smaller than the thickness dimension of the first thinning portion 22 and the second thinning portion 23. When an abnormality occurs in the battery and the internal pressure reaches a preset pressure value, the gas inside the battery will squeeze the explosion-proof valve 20. Since the connection between the first thinning portion 22 and the second thinning portion 23 is relatively weak, it is easy to be damaged when squeezed by the internal gas of the battery, which will cause the second thinning portion 23 to be at least partially separated from the first thinning portion 22, so that the explosion-proof valve 20 opens, and the gas inside the battery can be discharged to the outside from the position where the second thinning portion 23 is separated from the first thinning portion 22, thereby achieving pressure relief inside the battery.

[0038] The reinforcing sheet 30 is located on the side of the explosion-proof valve 20 facing the electrode assembly and is connected to the explosion-proof valve 20. Along the thickness direction X of the cover body 10, the outer contour of the reinforcing sheet 30 projected on the cover body 10 surrounds the explosion-proof hole 11, and the outer contour of the explosion-proof valve 20 projected on the cover body 10 surrounds the outer contour of the reinforcing sheet 30 projected on the cover body 10. It can be understood that the reinforcing sheet 30 is located on the side of the explosion-proof valve 20 facing the electrode assembly and is tightly connected to the explosion-proof valve 20. The connection method between the reinforcing sheet 30 and the explosion-proof valve 20 can be glue coating, patch adhesion, etc. When the reinforcing sheet 30 is set, the size of the outer contour of the reinforcing sheet 30 is between the outer contour of the explosion-proof hole 11 and the outer contour of the explosion-proof valve 20, and the outer contour area of ​​the reinforcing sheet 30 is larger than the outer contour area of ​​the explosion-proof hole 11, so that the reinforcing sheet 30 can play a certain reinforcing role on the second thinning portion 23 of the explosion-proof valve 20, so as to prevent the second thinning portion 23 from being deformed by external force when the battery is in normal use. At the same time, the outer contour area of ​​the reinforcement sheet 30 is smaller than the outer contour area of ​​the explosion-proof valve 20. Since the outer contour edge of the explosion-proof valve 20 is welded to the cover body 10, there may be protruding parts in the welding area. The outer contour area of ​​the reinforcement sheet 30 is smaller than the outer contour area of ​​the explosion-proof valve 20, so that the reinforcement sheet 30 can avoid these protruding parts, which can effectively ensure that the reinforcement sheet 30 is closely fitted to the explosion-proof valve 20, thereby ensuring the reinforcing effect of the reinforcement sheet 30.

[0039] The cover plate assembly satisfies: 1.2≤S1 / S2≤3; wherein S1 is the projection area of ​​the reinforcing sheet 30 on the cover plate body 10 along the thickness direction X, and S2 is the area of ​​the second thinning portion 23 (the area of ​​the second thinning portion 23 facing the reinforcing sheet 30). wherein S1 / S2 is generally in the range of 1.2 to 3, and S1 / S2 can be any value among 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, or a range value between any two values. S1 and S2 can be measured by a caliper: a caliper can be used to directly measure the corresponding dimensions of the corresponding projection, or directly measure the corresponding dimensions of the corresponding structure, and then obtain the corresponding area by calculation; it can also be measured by a three-dimensional scanner, which can obtain the three-dimensional data of the corresponding projection or structure, and then obtain the area of ​​the corresponding projection or structure by calculation. it should be noted that the performance of the reinforcing sheet 30 structure of the embodiment of the present application is represented by the state of the explosion-proof valve 20 under the test pressure. During the specific test, the heat spread of the battery was triggered by heating, and the state and opening of the explosion-proof valve 20 were observed. The test results of the embodiment and the comparative example are shown in the following table:

[0040]

[0041]

[0042] Combined with the above table, it can be seen that when the value range of S1 / S2 is within the range of 1.2 to 3, the explosion-proof valve 20 does not deform when subjected to appropriate pressure, and the explosion-proof valve 20 opens in time when simulating the thermal runaway state. Therefore, when S1 / S2 is within this range, the reinforcing sheet 30 has a good reinforcement effect when the battery is in normal working condition, and the battery can also ensure the timely opening of the explosion-proof valve 20 when it is in the thermal runaway state, and will not affect the normal opening of the explosion-proof valve 20. It can be seen from Comparative Examples 1, 2 and 3 that when S1 / S2 is less than 1.2, the explosion-proof valve 20 deforms when subjected to appropriate pressure, and the explosion-proof valve 20 opens in advance when simulating the thermal runaway state of the battery. When S1 / S2 is within the range of less than 1.2, the reinforcing sheet 30 loses its reinforcement effect on the explosion-proof valve 20, and the opening pressure of the explosion-proof valve 20 is reduced. It can be seen from Comparative Example 4 that when S1 / S2 is greater than 3, when simulating the thermal runaway state of the battery, when the preset valve opening pressure is reached inside the battery, the explosion-proof valve 20 does not open smoothly, affecting the normal exhaust of the battery; at the same time, the size of the reinforcement sheet 30 is designed to be larger, which will increase the production cost.

[0043] See also Figure 1 , Figure 3 , Figure 4 and Figure 5 In combination with the above embodiments, in some embodiments, along the thickness direction X of the cover body 10, the outer contour of the orthographic projection of the explosion-proof hole 11 on the explosion-proof valve 20 surrounds the notch 24. It can be understood that the area of ​​the outer contour of the explosion-proof hole 11 is larger than the area of ​​the outer contour of the notch 24. When the explosion-proof valve 20 is opened, it will break from the notch 24, so that the second thinning portion 23 is bounced open after the notch 24 breaks, so that the internal space of the battery shell can be connected to the outside world. The second thinning portion 23 that is bounced open can be ejected from the explosion-proof hole 11, so that the gas inside the battery can be discharged smoothly through the explosion-proof hole 11, avoiding the second thinning portion 23 from being stuck in the explosion-proof hole 11 and affecting the exhaust efficiency inside the battery.

[0044] See also Figure 1 , Figure 2 , Figure 3 and Figure 4In combination with the above embodiments, in some embodiments, the thickness of the second thinned portion 23 is a, and the thickness of the explosion-proof valve 20 at the position of the notch 24 is b, satisfying: 3≤a / b≤50. It can be understood that the depth of the notch 24 is inversely proportional to the thickness of the explosion-proof valve 20 at the position of the notch 24. The critical pressure value of the explosion of the explosion-proof valve 20 can be adjusted by adjusting the thickness b of the explosion-proof valve 20 at the position of the notch 24 (the critical pressure value of the explosion-proof valve 20 refers to the minimum pressure value required for the explosion. When the pressure inside the battery cell is greater than the critical pressure value of the explosion, the explosion-proof piece will open the valve to exhaust. For different systems, the critical explosion value of the explosion-proof piece is also different. The ternary system has PA and the iron-lithium system has PB, which satisfies: 0.7MPa≤PA≤1.1MPa, 0.4MPa≤PB≤0.8Mpa). When a and b satisfy: 3≤a / b≤50, the stability of the explosion of the explosion-proof valve 20 can be guaranteed, and the explosion-proof valve 20 can be opened in time to exhaust when the battery is in an abnormal state. Among them, a / b can be any value among 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or a range value between any two values. a and b can be measured by tools such as vernier calipers, laser rangefinders, optical projectors, etc. It should be noted that the performance of the explosion-proof valve 20 structure in the embodiment of the present application is represented by whether the explosion-proof valve 20 can open the valve in time when the internal pressure of the battery reaches a preset pressure under the condition of battery heat spread. During the specific test, the battery heat spread is triggered by heating, and the internal pressure of the battery is measured to observe the opening of the battery explosion-proof valve 20. The test results of the embodiment are as follows:

[0045]

[0046] It can be seen from the above table that when the thickness a of the second thinned portion 23 and the thickness b of the explosion-proof valve 20 at the position of the notch 24 satisfy: 3≤a / b≤50, when the internal gas pressure of the battery reaches the preset pressure, the explosion-proof valve 20 can be opened in time to release the gas inside the battery to ensure the safety of the battery.

[0047] See also Figure 1 , Figure 3 and Figure 4In combination with the above embodiments, in some embodiments, the reinforcing sheet 30 is arranged in close contact with the explosion-proof valve 20, and along the thickness direction X of the cover body 10, the outer contour of the orthographic projection of the reinforcing sheet 30 on the explosion-proof valve 20 surrounds the notch 24, and satisfies: 1mm≤A≤5mm. Wherein, A is the distance from the outer contour of the orthographic projection of the notch 24 on the reinforcing sheet 30 along the thickness direction X to the outer contour of the reinforcing sheet 30. It can be understood that when the distance from the outer contour of the orthographic projection of the notch 24 on the reinforcing sheet 30 along the thickness direction X to the outer contour of the reinforcing sheet 30 is within the range of 1mm to 5mm, the reinforcing sheet 30 has a good reinforcement effect, and under normal use of the battery, it can play a certain protective role on the notch 24, preventing the explosion-proof valve 20 from being deformed by external forces and the notch 24 from being damaged. When A<1mm, the reinforcement effect of the reinforcing sheet 30 is not obvious, and the notch 24 is also easily damaged when the explosion-proof valve 20 is subjected to external forces. When A>5 mm, the size of the reinforcing sheet 30 is too large, which may cause dimensional interference with the lower plastic and other parts, and increase the production and processing costs.

[0048] See also Figure 1 , Figure 3 and Figure 4 , combined with the above embodiments, in some embodiments, the critical pressure value of both the explosion-proof valve 20 and the reinforcement sheet 30 is PA, when the temperature of the explosion-proof valve 20 is lower than the preset temperature, under the reinforcement effect of the reinforcement sheet 30, it satisfies: PA>1.1Mpa; when the temperature of the explosion-proof valve 20 is higher than the preset temperature, it satisfies: 0.5MPa≤PA≤0.7Mpa. It can be understood that for ternary system batteries, during the normal use of the battery, the reinforcement sheet 30 can play a reinforcing role for the explosion-proof valve 20. In this case, the critical pressure value of both the explosion-proof valve 20 and the reinforcement sheet 30 is greater than>1.1Mpa, that is, when the battery is in normal use, the explosion-proof valve 20 withstands a large force without deformation and rupture, ensuring that the explosion-proof valve 20 can be used normally. When the battery has thermal runaway, the reinforcement sheet 30 can soften and reduce its strength. When the pressure inside the battery reaches the critical pressure value, the explosion-proof valve 20 can be opened normally to relieve the pressure inside the battery. Among them, the critical pressure value of the battery can be set in the range of 0.5Mpa to 0.7Mpa. Compared with the general ternary system battery (the critical pressure value of the explosion-proof valve of the ternary system battery when it is opened is: 0.7MPa≤PA≤1.1Mpa), it can be set smaller, which can ensure that when the battery has thermal runaway, the reinforcing sheet 30 loses its reinforcing effect, the critical pressure value of the explosion-proof valve 20 is reduced, the response speed is faster, and it can be opened quickly to ensure the exhaust effect of the explosion-proof valve 20.

[0049] Alternatively, for the iron-lithium system battery, the critical pressure value for the rupture of both the explosion-proof valve 20 and the reinforcement sheet 30 is PB. When the temperature of the explosion-proof valve 20 is lower than the preset temperature, under the reinforcement effect of the reinforcement sheet 30, the following conditions are satisfied: PB>0.8Mpa; when the temperature of the explosion-proof valve 20 is higher than the preset temperature, the following conditions are satisfied: 0.2MPa≤PB≤0.4Mpa. It can be understood that during the normal use of the battery, the reinforcement sheet 30 can strengthen the explosion-proof valve 20. In this case, the critical pressure value for the rupture of both the explosion-proof valve 20 and the reinforcement sheet 30 is greater than>0.8Mpa, that is, when the battery is in normal use, the explosion-proof valve 20 withstands a large force without deformation and rupture, ensuring that the explosion-proof valve 20 can be used normally. When the battery has thermal runaway, the reinforcement sheet 30 can soften and reduce its strength. When the pressure inside the battery reaches the critical pressure value, the explosion-proof valve 20 can be opened normally to relieve the pressure inside the battery. Among them, the critical pressure value of the battery can be set in the range of 0.2MPa to 0.4Mpa. Compared with general iron-lithium system batteries (the critical pressure value of the explosion-proof valve of iron-lithium system batteries when opening is: 0.4MPa≤PB≤0.8MPa), it can be set smaller, which can ensure that when the battery has thermal runaway, the reinforcing plate 30 loses its reinforcing effect, the critical pressure value of the explosion-proof valve 20 is reduced, the response speed is faster, and it can be opened quickly to ensure the exhaust effect of the explosion-proof valve 20.

[0050] See also Figure 1 , Figure 2 and Figure 3 In combination with the above embodiments, in some embodiments, the notch 24 is arranged around the second thinning portion 23 and is located on the side of the explosion-proof valve 20 away from the reinforcing sheet 30. It can be understood that the notch 24 is arranged between the first thinning portion 22 and the second thinning portion 23, and can be used to adjust the critical pressure value of the explosion of the explosion-proof valve 20. The depth of the notch 24 is different, and the critical pressure value of the explosion of the explosion-proof valve 20 is also different. The notch 24 is located on the side of the explosion-proof valve 20 away from the reinforcing sheet 30. When the battery is abnormal, the gas generated inside will impact the second thinning portion 23 on the explosion-proof valve 20. Since the opening of the notch 24 is in the same direction as the impact of the gas inside the battery, when the gas impacts the second thinning portion 23, the second thinning portion 23 is slightly convex upward, and a part of the outer circumference of the second thinning portion 23 can be filled into the inside of the notch 24, allowing the second thinning portion 23 to be deformed to a greater extent, so that when the battery is abnormal, the second thinning portion 23 is more easily separated from the first thinning portion 22. If the opening of the notch 24 is opened toward the reinforcing plate 30, when the second thinning portion 23 is impacted by gas, the degree of upward bulging deformation is smaller (there is not much space for the second thinning portion 23 to deform), which will increase the difficulty of separating the second thinning portion 23 from the first thinning portion 22.

[0051] See also Figure 1, combined with the above embodiments, in some embodiments, the softening temperature of the reinforcing sheet 30 is T, satisfying: 65°<T≤110°. It can be understood that, through experience and experiments, when the battery triggers thermal runaway, the temperature of the explosion-proof valve is greater than 65°C at the moment before the valve is opened. In order to meet the reinforcement effect of the explosion-proof valve 20 and not affect the exhaust of the explosion-proof valve 20, as a preferred embodiment, the softening failure critical temperature of the reinforcing sheet 30 can be set at 65°C, that is, when the temperature exceeds 65°C, the reinforcing sheet 30 will soften and the explosion-proof valve 20 can be exhausted in time. In order to withstand the high temperature baking during the battery manufacturing process, the reinforcing sheet 30 also needs to meet the requirements that when the temperature is less than or equal to 110°C, it cannot flow and its position will not change. After the baking is completed, the reinforcing sheet 30 will restore its reinforcement effect.

[0052] See also Figure 1 In combination with the above embodiments, in some embodiments, the thickness of the reinforcing sheet 30 is t, which satisfies: 0.5mm<t≤1mm, preferably, t=0.6mm. When the thickness of the reinforcing sheet 30 is within this range, the reinforcing sheet 30 can play a good reinforcing role on the explosion-proof valve 20. When the thickness of the reinforcing sheet 30 is less than or equal to 0.5mm, the thickness of the reinforcing sheet 30 is too thin, so that it cannot achieve the reinforcement effect. When the thickness of the reinforcing sheet 30 is greater than 1mm, the thickness of the reinforcing sheet 30 is too thick, and the reinforcing sheet 30 is easy to interfere with the size of the lower plastic and other parts when it is set.

[0053] See also Figure 1 In combination with the above embodiments, in some embodiments, the reinforcing sheet 30 is made of polypropylene material or polyolefin material. These materials will soften when reaching a specific temperature, so that the reinforcing sheet 30 loses its reinforcing function. When the temperature is lower than the specific temperature, the reinforcing sheet 30 will recover and play the reinforcing function again.

[0054] A single cell battery comprises a shell, an electrode assembly and a cover assembly of any one of the above. The shell has a receiving cavity. The electrode assembly is arranged in the receiving cavity. The cover assembly covers the receiving cavity and is connected to the shell. A single cell battery is an independent battery unit that can generate electrical energy for use in electronic equipment or systems. A single cell battery usually has an electrode assembly including a positive electrode, a negative electrode, an electrolyte and a diaphragm, and also comprises a shell, the shell has a receiving cavity, and the electrode assembly is arranged in the receiving cavity. The single cell battery also comprises a cover assembly, which is connected to the shell and covers the receiving cavity, so that the structure inside the receiving cavity has a good working environment and is not affected by external factors.

[0055] A battery pack, including the above-mentioned single cell, or the above-mentioned cover assembly. The battery pack is a whole composed of multiple single cells, usually including battery cells, battery management system (BMS), connectors, protective shell and other components. Its main function is to provide higher voltage, capacity and energy density to meet the needs of various applications. Battery packs are usually used in electric vehicles, drones, portable electronic devices, energy storage systems, emergency power supplies and other fields.

[0056] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0057] The cover plate assembly, single cell and battery pack provided in the embodiments of the present application are introduced in detail above, and the principles and implementation methods of the present application are explained by using specific examples. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A cover plate assembly, characterized in that: include: The cover body has explosion-proof holes; An explosion-proof valve, covering the explosion-proof hole, the explosion-proof valve comprises a connecting portion, a first thinned portion and a second thinned portion, the first thinned portion is connected to the second thinned portion in a surrounding manner, a notch is provided at the connection between the first thinned portion and the second thinned portion, the connecting portion is connected to the first thinned portion in a surrounding manner, and is connected to the cover plate body; A reinforcing sheet, located on a side of the explosion-proof valve facing the electrode assembly and connected to the explosion-proof valve, along the thickness direction of the cover plate body, the outer contour of the reinforcing sheet projected on the cover plate body surrounds the explosion-proof hole, and the outer contour of the explosion-proof valve projected on the cover plate body surrounds the outer contour of the reinforcing sheet projected on the cover plate body; The cover plate assembly satisfies: 1.2≤S1 / S2≤3; Wherein, S1 is the projection area of ​​the reinforcing sheet on the cover plate body along the thickness direction, and S2 is the area of ​​the second thinned portion.

2. The cover plate assembly according to claim 1, characterized in that: Along the thickness direction of the cover plate body, the outer contour of the orthographic projection of the explosion-proof hole on the explosion-proof valve surrounds the notch.

3. The cover plate assembly according to claim 1, characterized in that: The thickness of the second thinned portion is a, and the thickness of the explosion-proof valve at the notch position is b, satisfying: 3≤a / b≤50.

4. The cover plate assembly according to claim 1, characterized in that: The reinforcing sheet is fitted with the explosion-proof valve, and along the thickness direction of the cover plate body, the outer contour of the orthographic projection of the reinforcing sheet on the explosion-proof valve surrounds the notch and satisfies: 1mm≤A≤5mm; Wherein, A is the distance from the outer contour of the projection of the notch on the reinforcing sheet along the thickness direction to the outer contour of the reinforcing sheet.

5. The cover plate assembly according to claim 1, characterized in that: When the cover plate assembly is used for a ternary system battery, the critical pressure value for the rupture of both the explosion-proof valve and the reinforcement sheet is PA, and when the temperature of the explosion-proof valve is lower than the preset temperature, the following conditions are satisfied: PA>1.1Mpa; when the temperature of the explosion-proof valve is higher than the preset temperature, the following conditions are satisfied: 0.5MPa≤PA≤0.7Mpa; When the cover plate assembly is used for an iron-lithium battery, the critical pressure value for the rupture of both the explosion-proof valve and the reinforcement plate is PB, and when the temperature of the explosion-proof valve is lower than a preset temperature, PB>0.8Mpa is satisfied; when the temperature of the explosion-proof valve is higher than a preset temperature, 0.2MPa≤PB≤0.4Mpa is satisfied.

6. The cover plate assembly according to claim 1, characterized in that: The notch is arranged around the second thinned portion and is located on a side of the explosion-proof valve away from the reinforcing sheet.

7. The cover plate assembly according to claim 1, characterized in that: The softening temperature of the reinforcing sheet is T, which satisfies: 65°<T≤110°.

8. The cover plate assembly according to claim 1, characterized in that: The thickness of the reinforcing sheet is t, which satisfies: 0.5 mm < t ≤ 1 mm.

9. The cover plate assembly according to claim 1, characterized in that: The reinforcing sheet is made of polypropylene material or polyolefin material.

10. A single cell battery, characterized in that: include: A housing having a receiving cavity; An electrode assembly is disposed in the accommodating cavity; The cover plate assembly according to any one of claims 1 to 9, wherein the cover plate assembly covers the accommodating cavity and is connected to the shell.

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