Single battery, battery pack and electric device

Abstract

The application discloses a single battery, a battery pack and an electric device, and belongs to the technical field of batteries, and comprises a shell with a containing cavity; a cover plate is connected with the shell and covers and seals the containing cavity, and the cover plate is provided with an explosion-proof hole; an explosion-proof valve covers the explosion-proof hole, and the explosion-proof valve comprises a bearing part, a weak part, a convex part and a concave part which are connected in sequence from outside to inside and surround the explosion-proof valve, the bearing part is connected with the cover plate, the weak part is configured to be damaged when subjected to a preset pressure impact, the convex part protrudes towards a side away from an electrode assembly, and the concave part is recessed towards a side close to the electrode assembly from the connection position of the weak part; wherein the area of the convex part is S1 mm 2 , the area of the concave part is S2 mm 2 , and the following condition is met: 0.1≤S2 / (S1+S2)≤0.4. By limiting the ratio of the area of the concave part to the total area of the concave part and the convex part, it can be ensured that the explosion-proof valve can fully absorb and disperse stress, and the problems of deformation cracking or early valve opening of the explosion-proof valve caused by local stress concentration can be avoided.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a single cell, a battery pack, and an electrical device. Background Technology

[0002] Lithium-ion batteries are widely used in various fields such as transportation power supplies, power storage, new energy storage power supplies, and aerospace and military industries due to their advantages such as large capacity, high operating voltage, strong charge retention, and long cycle life. The cover plate of the battery typically integrates structures such as terminals and explosion-proof valves. The explosion-proof valve's main function is to relieve pressure and vent gas, allowing the directional release of high-temperature, high-pressure gas inside the cell when thermal runaway occurs due to mechanical impact, internal abnormal short circuits, or other reasons, thereby improving the safety performance of the battery pack. However, during the individual cell manufacturing process, such as electrolyte injection, pre-charge formation, and capacity testing, the repeated positive and negative pressure differences between the battery's internal environment and the external environment cause problems such as deformation, cracking, and premature opening of the explosion-proof valve, seriously affecting the battery manufacturing yield and safety performance. Summary of the Invention

[0003] Purpose of the invention: This application provides a single cell, a battery pack, and an electrical device, aiming to solve the technical problems of deformation, cracking, and premature opening of the explosion-proof valve due to pressure difference during battery manufacturing.

[0004] Technical solution: This application provides a single-cell battery, including:

[0005] The housing has a receiving cavity;

[0006] Electrode assembly, the electrode assembly is located within the receiving cavity;

[0007] A cover plate is connected to the housing and seals the receiving cavity; the cover plate is provided with explosion-proof holes.

[0008] An explosion-proof valve, with an explosion-proof valve cover sealing the explosion-proof hole, includes a support portion, a weak portion, a protrusion and a recess connected in sequence from the outside to the inside. The support portion is connected to the cover plate. The weak portion is configured to be destroyed when subjected to a preset pressure impact. The protrusion protrudes from the connection with the weak portion toward the side away from the electrode assembly, and the recess is recessed toward the side closer to the electrode assembly.

[0009] The area of ​​the protrusion is S1mm. 2 The area of ​​the concave part is S2mm 2 The condition is satisfied that: 0.1≤S2 / (S1+S2)≤0.4.

[0010] In some embodiments, the area of ​​the explosion-proof valve is S mm. 2 The condition is satisfied that 0.4 ≤ (S1 + S2) / S ≤ 0.8.

[0011] In some embodiments, a single cell satisfies: 0.35 ≤ S1 / S ≤ 0.6.

[0012] In some embodiments, a single cell satisfies: 0.1 ≤ S² / S ≤ 0.2.

[0013] In some embodiments, in the thickness direction of the cover plate, the weak portion includes a first surface close to the electrode assembly, and in the thickness direction, the maximum dimension between the protrusion and the first surface is B mm, and the minimum dimension between the recess and the first surface is C mm, satisfying: 0.15≤BC≤0.5.

[0014] In some embodiments, the maximum dimension of the support portion in the thickness direction is A mm, satisfying: C>A, 0.4≤A≤0.6.

[0015] In some embodiments, the support portion is connected to the side of the cover plate near the electrode assembly, and the protrusion extends into the explosion-proof hole.

[0016] In some embodiments, a limiting groove is provided on the side of the cover plate near the electrode assembly. The limiting groove surrounds the explosion-proof hole. The limiting groove is provided on the side of the cover plate near the electrode assembly, and the bearing part is provided in the limiting groove.

[0017] Accordingly, this application provides a battery pack including the aforementioned single battery cell.

[0018] Accordingly, embodiments of this application provide an electrical device, including the aforementioned single battery cell, or including the aforementioned battery pack.

[0019] Beneficial Effects: The single-cell battery of this application embodiment includes a casing, an electrode assembly, a cover plate, and an explosion-proof valve. The casing has a receiving cavity; the electrode assembly is located in the receiving cavity; the cover plate is connected to the casing and seals the receiving cavity, and the cover plate has an explosion-proof hole; the explosion-proof valve seals the explosion-proof hole, and the explosion-proof valve includes a support portion, a weak portion, a protrusion, and a recess that are sequentially connected from the outside to the inside. The support portion is connected to the cover plate, the weak portion is configured to be destroyed when subjected to a preset pressure impact, the protrusion protrudes from the connection point with the weak portion toward the side away from the electrode assembly, and the recess is recessed toward the side closer to the electrode assembly; wherein, the area of ​​the protrusion is S1mm. 2 The area of ​​the concave part is S2mm 2 The following condition must be met: 0.1 ≤ S2 / (S1 + S2) ≤ 0.4. By limiting the ratio of the area of ​​the concave portion to the total area of ​​the concave and convex portions, it is ensured that the design of the convex and concave portions can fully absorb and disperse the stress brought to the explosion-proof valve by the pressure difference between the cavity and the outside of the casing during the production of a single cell. This avoids local stress concentration that could lead to deformation of the explosion-proof valve, resulting in cracking or premature opening of the valve. As a result, the production yield of single cells can be effectively improved, as well as the safety and reliability of single cells.

[0020] The battery pack of this application embodiment includes the above-described single battery cell, and therefore the battery pack can have all the technical features and beneficial effects of the above-described single battery cell, which will not be repeated here.

[0021] The electrical device in this application includes the above-mentioned single battery or battery pack. Therefore, the electrical device can have all the technical features and beneficial effects of the above-mentioned single battery or battery pack, which will not be repeated here. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is an exploded view of a single battery cell according to an embodiment of this application;

[0024] Figure 2 This is a cross-sectional view of a cover plate according to an embodiment of this application;

[0025] Figure 3 This is a top view of an explosion-proof valve according to an embodiment of this application;

[0026] Figure 4 This is a bottom view of an explosion-proof valve according to an embodiment of this application;

[0027] Figure 5 This is a cross-sectional view of an explosion-proof valve according to an embodiment of this application.

[0028] Reference numerals: 1. Housing; 2. Electrode assembly; 3. Cover plate; 4. Explosion-proof valve; 10. Receiving cavity; 30. Explosion-proof hole; 31. Limiting groove; 40. Bearing part; 41. Weak part; 42. Protrusion; 43. Recess; 310. Bottom wall; 410. First surface; 411. Score; X, Thickness direction. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] In the description of this application, it should be understood that the terms "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, and "at least one" can mean one, two, or more, unless otherwise explicitly specified. In the description of this application, "perpendicular" means completely perpendicular to 90° or almost completely perpendicular, for example, the range of included angles between 80° and 100° is considered perpendicular. Similarly, "parallel" means completely parallel or almost completely parallel, for example, the range of completely parallel angles between 10° is considered parallel.

[0031] The applicant noted that lithium-ion batteries, due to their advantages such as large capacity, high operating voltage, strong charge retention, and long cycle life, are currently widely used in various fields including transportation power supplies, power storage, new energy storage power supplies, and aerospace and military industries. The cover plate in a battery typically integrates structures such as terminals and explosion-proof valves. The explosion-proof valve's main function is to release pressure and vent gas, allowing the directional release of high-temperature, high-pressure gas inside the cell when thermal runaway occurs due to mechanical impact, internal abnormal short circuits, or other reasons, thereby improving the safety performance of the battery pack. However, during the individual cell manufacturing process, such as electrolyte injection, pre-charge formation, and capacity testing, repeated positive and negative pressure differences exist between the battery's internal environment and the external environment, leading to problems such as deformation, cracking, and premature opening of the explosion-proof valve, seriously affecting battery process yield and safety performance.

[0032] In view of this, the single-cell battery of this application embodiment includes a casing, an electrode assembly, a cover plate, and an explosion-proof valve. The single-cell battery of this application embodiment includes a casing, an electrode assembly, a cover plate, and an explosion-proof valve. The casing has a receiving cavity; the electrode assembly is located within the receiving cavity; the cover plate is connected to the casing and seals the receiving cavity, and the cover plate has an explosion-proof hole; the explosion-proof valve seals the explosion-proof hole, and the explosion-proof valve includes a supporting portion, a weak portion, a protrusion, and a recess connected sequentially from the outside to the inside. The supporting portion is connected to the cover plate, the weak portion is configured to be destroyed when subjected to a preset pressure impact, the protrusion protrudes from its connection with the weak portion toward the side away from the electrode assembly, and the recess is recessed toward the side closer to the electrode assembly; wherein, the area of ​​the protrusion is S1mm. 2 The area of ​​the concave part is S2mm 2The following condition must be met: 0.1 ≤ S2 / (S1 + S2) ≤ 0.4. By limiting the ratio of the area of ​​the concave portion to the total area of ​​the concave and convex portions, it is ensured that the convex and concave portions can fully absorb and disperse the stress brought to the explosion-proof valve by the pressure difference between the cavity and the outside of the casing during the production of a single cell. This avoids local stress concentration that could lead to deformation of the explosion-proof valve, resulting in cracking or premature opening of the valve. As a result, the production yield of single cells can be effectively improved, as well as the safety and reliability of single cells.

[0033] In this application, a single battery cell may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application are not limited to this. A single battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to this either. Single batteries are generally classified into three types according to their packaging method: cylindrical single batteries, square single batteries, and pouch single batteries, and the embodiments of this application are not limited to this either.

[0034] The single-cell battery, battery pack, and power-consuming device of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0035] Figure 1 This is an exploded view of a single battery cell according to an embodiment of this application; Figure 2 This is a cross-sectional view of a cover plate 3 according to an embodiment of this application; Figure 3 This is a top view of an explosion-proof valve 4 according to an embodiment of this application; Figure 4 This is a bottom view of an explosion-proof valve 4 according to an embodiment of this application; Figure 5 This is a cross-sectional view of an explosion-proof valve 4 according to an embodiment of this application.

[0036] refer to Figures 1 to 5This application provides a single-cell battery, including a housing 1, an electrode assembly 2, a cover plate 3, and an explosion-proof valve 4. The housing 1 has a receiving cavity 10; the electrode assembly 2 is located within the receiving cavity 10; the cover plate 3 is connected to the housing 1 and seals the receiving cavity 10, the cover plate 3 has an explosion-proof hole 30, and the explosion-proof valve 4 seals the explosion-proof hole 30. The explosion-proof valve 4 includes a support portion 40, a weak portion 41, a protrusion 42, and a recess 43 connected sequentially from the outside to the inside. Specifically, the support portion 40 is connected to the weak portion 41, the weak portion 41 is connected to the protrusion 42, and the protrusion 42 is connected to the recess 43. The weak portion 41 is configured to be destroyed when subjected to a preset pressure impact. When the internal pressure of the single-cell battery is too high (e.g., due to overcharging), the weak portion 41 of the explosion-proof valve 4 is destroyed by the preset pressure to release the gas inside the single-cell battery, thereby reducing the internal pressure of the single-cell battery and preventing the single-cell battery from exploding due to excessively rapid internal pressurization. The protrusion 42 protrudes from the connection point with the weak portion 41 towards the side away from the electrode assembly 2, while the recess 43 is recessed towards the side closer to the electrode assembly 2. The arrangement of the protrusion 42 and the recess 43 can prevent stress concentration. The area of ​​the protrusion 42 is S1mm. 2 The area of ​​the recess 43 is S2mm. 2 The following condition is satisfied: 0.1≤S2 / (S1+S2)≤0.4. By limiting the ratio of the area of ​​the recess 43 to the total area of ​​the recess 43 and the protrusion 42, it is ensured that the protrusion 42 and the recess 43 can fully absorb and disperse the stress brought to the explosion-proof valve 4 by the pressure difference between the cavity 10 and the shell 1 during the production of a single cell. This avoids the problem of local stress concentration causing deformation of the explosion-proof valve 4, which could lead to cracking or premature opening of the explosion-proof valve 4. As a result, the production yield of the single cell can be effectively improved, as well as the safety and reliability of the single cell.

[0037] Understandably, if the relative area of ​​the recess 43 is too small, it cannot adequately absorb and disperse the internal pressure of the single cell, thus restricting the explosion-proof valve 4 from opening and releasing pressure as it should, preventing timely and effective valve opening. This could lead to the internal pressure of the single cell not being released in time, increasing the risk of danger to the single cell. If the relative area of ​​the recess 43 is too large, it may cause abnormal deformation and cracking of the protrusion 42 during the single cell manufacturing process. The ratio of the area of ​​the recess 43 to the total area of ​​the recess 43 and the protrusion 42 can avoid problems such as restricted valve opening and abnormal deformation and cracking of the protrusion 42. During the single cell manufacturing process, the explosion-proof valve 4 can more effectively disperse the pressure from the inside and outside of the single cell, making the stress distribution on the explosion-proof valve 4 more uniform, reducing the risk of local stress concentration, and enabling the explosion-proof valve 4 to open in a timely and accurate manner when subjected to a preset pressure impact, preventing the single cell from catching fire or exploding, and improving the safety performance of the single cell.

[0038] In some embodiments, the area of ​​the protrusion 42 is S1mm. 2 The area of ​​the recess 43 is S2mm. 2 The area of ​​explosion-proof valve 4 is S mm. 2 The following condition must be met: 0.4 ≤ (S1 + S2) / S ≤ 0.8. When the ratio of the total area S1 of the protrusion 42 and the recess 43 to the area S of the explosion-proof valve 4 is too large, it is understandable that the protrusion 42 and the recess 43 occupy too much area in the explosion-proof valve 4, thus encroaching on the space of the weak part 41. This may cause the weak part 41 to fail to be properly destroyed when subjected to a preset pressure, affecting the function of the explosion-proof valve 4 in releasing internal gas. When the ratio of the area S1 of the protrusion 42 and the recess 43 to the area S of the explosion-proof valve 4 is too small, the area of ​​the protrusion 42 is too small, and it cannot fully absorb and disperse the pressure difference stress from the single cell production process. This may easily cause the weak part 41 to crack due to stress concentration or cause the explosion-proof valve 4 to open prematurely, reducing the safety and reliability of the single cell. By limiting the ratio of the total area of ​​the protrusion 42 and the recess 43 to the area S of the explosion-proof valve 4, it can be ensured that the protrusion 42 and the recess 43 can fully absorb and disperse stress. This ensures that the protrusion 42 is neither too small to effectively disperse stress nor too large to affect the pressure relief function of the explosion-proof valve 4. A reasonable area ratio helps the explosion-proof valve 4 to quickly release internal gas and reduce internal pressure when the internal pressure of a single battery cell is too high, thereby improving the safety and reliability of the single battery cell.

[0039] In some embodiments, the area of ​​the explosion-proof valve 4 is S mm. 2 The area of ​​the protrusion 42 is S1mm. 2 The following condition must be met: 0.35 ≤ S1 / S ≤ 0.6. That is, the area of ​​the protrusion 42 on the explosion-proof valve 4 should be between 35% and 60%. When the area of ​​the protrusion 42 is too large, although it typically bears the main responsibility for absorbing and dispersing stress, excessive elastic deformation due to the internal and external pressure difference during production may occur, potentially exceeding the material's tolerance limit. This could lead to abnormal outward deformation of the explosion-proof valve 4, or even cracking, affecting the safety and reliability of the individual battery. When the area of ​​the protrusion 42 is too small, it cannot fully perform its stress absorption and dispersion functions, making it prone to denting during the manufacturing process of the individual battery. By rationally designing the ratio range of the area S1 of the protrusion 42 to the area S of the explosion-proof valve 4, on the one hand, stress can be effectively dispersed and absorbed, ensuring the structural stability of the explosion-proof valve 4 and reducing the risk of deformation and cracking of the explosion-proof valve 4; on the other hand, it can prevent the explosion-proof valve 4 from opening prematurely, and can open normally when the internal pressure of the battery reaches the preset value, releasing the pressure in time, thus improving the safety and reliability of the single battery.

[0040] In some embodiments, the area of ​​the explosion-proof valve 4 is S mm. 2 The area of ​​the recess 43 is S2mm. 2 The condition is satisfied: 0.1 ≤ S² / S ≤ 0.2. That is, the area of ​​the recess 43 on the explosion-proof valve 4 is between 10% and 20%. If the area of ​​the recess 43 is too small, it may cause the valve to open improperly after gas is generated inside the individual battery during the capacity grading process. The capacity grading process involves sorting individual batteries by capacity, measuring their actual capacity by charging and discharging them, and grouping batteries with similar capacities together. During charging and discharging, gas may be generated inside the individual battery due to chemical reactions, putting pressure on the explosion-proof valve. Insufficient area of ​​the recess 43 prevents it from fully absorbing and dispersing the internal pressure of the individual battery, thus restricting the explosion-proof valve 4 from opening properly and effectively. This may prevent the internal pressure of the individual battery from being released in time, increasing the risk of danger. If the area of ​​the recess 43 is too large, it will occupy the area of ​​the protrusion 42, potentially causing abnormal deformation and cracking of the protrusion 42 during the individual battery manufacturing process. By rationally designing the ratio range of the area S2 of the recess 43 to the area S of the explosion-proof valve 4, the problem of valve opening caused by the small area of ​​the recess 43 and the problem of abnormal deformation and cracking of the protrusion 42 caused by the large area can be effectively prevented. This ensures the stable performance of the explosion-proof valve 4, which can open normally when the internal pressure of the battery reaches the preset value, release pressure in time, and improve the safety and reliability of the single battery.

[0041] In the embodiments of this application, explosion-proof valves 4 with different S, S1 and S2 are set and welded to the cover plate 3 for actual testing and verification. The abnormal situation of the explosion-proof valve in the cell manufacturing process is tracked, and the verification results are shown in Table 1.

[0042] Table 1:

[0043]

[0044] Referring to Examples 1 to 9 in Table 1, the individual cells all satisfy 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8, 0.35≤S1 / S≤0.6, and 0.1≤S2 / S≤0.2, and there are no abnormal cracking issues with the explosion-proof valve 4 during the individual cell manufacturing process. It can be understood that by reasonably setting the dimensions of the recess 43, the protrusion 42, and the explosion-proof valve 4, it is ensured that the protrusion 42 and the recess 43 can fully absorb and disperse the stress on the explosion-proof valve 4 caused by the pressure difference between the cavity 10 and the shell 1 during the individual cell production process. This avoids local stress concentration leading to deformation of the explosion-proof valve 4, which could then cause cracking or premature opening of the explosion-proof valve 4. Therefore, the production yield of the individual cells can be effectively improved, as well as the safety and reliability of the individual cells.

[0045] Referring to Comparative Example 1 in Table 1, the individual cells meet the requirements of 0.4≤(S1+S2) / S≤0.8 and 0.35≤S1 / S≤0.6, but S2 / (S1+S2) is less than 0.1 and S2 / S is less than 0.1, failing to meet the requirements of 0.1≤S2 / (S1+S2)≤0.4 and 0.1≤S2 / S≤0.2. The verification result is that the area of ​​the concave portion 43 is too small. During the individual cell capacity testing process, the explosion-proof valve 4 cracks due to high internal gas pressure, with a rate of approximately 0.245%. It is understandable that because the area of ​​the concave portion 43 is relatively small, it cannot fully absorb and disperse the internal pressure of the individual cell. When the internal pressure cannot be effectively dispersed by the concave portion 43, the local pressure borne by the explosion-proof valve 4 becomes excessive. As the internal gas pressure continues to rise, the weak point 41 is prone to cracking.

[0046] Referring to Comparative Example 2 in Table 1, the individual cells meet the requirements of 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8, and 0.35≤S1 / S≤0.6. However, S2 / S is less than 0.1, failing to meet the requirement of 0.1≤S2 / S≤0.2. The verification result is that the area of ​​the concave portion 43 is too small. After gas is generated inside the individual cell during the capacity grading process, there is still a problem of constrained valve opening. It is understandable that because the area of ​​the concave portion 43 is relatively small, it cannot fully absorb and disperse the internal pressure of the individual cell, resulting in the explosion-proof valve 4 being restricted from opening and releasing pressure normally, and thus unable to open the valve in a timely and effective manner.

[0047] Referring to Comparative Example 3 in Table 1, the individual cells meet the requirements of 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8, and 0.35≤S1 / S≤0.6. However, S2 / S is greater than 0.2, failing to meet the requirement of 0.1≤S2 / S≤0.2. The verification result shows that the area of ​​the concave portion 43 is too large, and the explosion-proof valve 4 has a recessed problem in the individual cell manufacturing process. It is understandable that the relatively large area of ​​the concave portion 43 will occupy the area of ​​the protruding portion 42, causing the protruding portion 42 to deform and crack abnormally during the individual cell manufacturing process.

[0048] Referring to Comparative Example 4 in Table 1, the individual cells meet the requirements of 0.4≤(S1+S2) / S≤0.8 and 0.35≤S1 / S≤0.6. However, S2 / (S1+S2) is greater than 0.4 and S2 / S is greater than 0.2, failing to meet the requirements of 0.1≤S2 / (S1+S2)≤0.4 and 0.1≤S2 / S≤0.2. The verification result indicates that the area of ​​the concave portion 43 is too large, leading to a problem of the explosion-proof valve 4 being recessed during the individual cell manufacturing process. It is understandable that the relatively large area of ​​the concave portion 43 occupies the area of ​​the protruding portion 42, causing abnormal deformation and cracking of the protruding portion 42 during the individual cell manufacturing process.

[0049] Referring to Comparative Examples 5 and 6 in Table 1, the individual cells meet the requirements of 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8, and 0.1≤S2 / S≤0.2. However, S1 / S is less than 0.35, failing to meet the requirement of 0.35≤S1 / S≤0.6. The verification result shows that the area of ​​the protruding part 42 is too small, and the explosion-proof valve 4 in the individual cell manufacturing process has a dent problem. It is understandable that the area of ​​the protruding part 42 is relatively small compared to the total area of ​​the explosion-proof valve 4, which cannot fully absorb and disperse the pressure difference stress from the individual cell manufacturing process. This leads to the stress being concentrated in other areas of the explosion-proof valve 4, causing the explosion-proof valve 4 to dent.

[0050] Referring to Comparative Examples 7 and 8 in Table 1, the individual cells meet the requirements of 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8, and 0.1≤S2 / S≤0.2. However, S1 / S is greater than 0.6, failing to meet the requirement of 0.35≤S1 / S≤0.6. The verification result is that the area of ​​the protruding part 42 is too large, and the explosion-proof valve 4 cracks due to high internal gas pressure during the individual cell manufacturing process. It is understandable that the area of ​​the protruding part 42 is relatively large compared to the total area of ​​the explosion-proof valve 4. During the individual cell manufacturing process, the stress caused by the internal and external pressure difference causes excessive elastic deformation, exceeding the bearing limit of the explosion-proof valve 4 material. This leads to abnormal deformation of the explosion-proof valve 4, and even cracking, affecting the safety and reliability of the individual cells.

[0051] In some embodiments, in the thickness direction X of the cover plate 3, the weak portion 41 includes a first surface 410 close to the electrode assembly 2. In the thickness direction X, the maximum dimension between the protrusion 42 and the first surface 410 is B mm, and the minimum dimension between the recess 43 and the first surface 410 is C mm, satisfying: 0.15 ≤ BC ≤ 0.5. It is understood that the range of the difference between the maximum dimension B between the protrusion 42 and the first surface 410 and the minimum dimension C between the recess 43 and the first surface 410 is the distance between the highest point of the protrusion 42 and the lowest point of the recess 43. When the difference between the maximum dimension B between the protrusion 42 and the first surface 410 and the minimum dimension C between the recess 43 and the first surface 410 is large, the protrusion 42 protrudes relatively high, resulting in a small distance between the protrusion 42 and the side of the cover plate 3 away from the electrode assembly 2. This poses a risk of damage to the explosion-proof valve 4 during the single-cell manufacturing process. On the other hand, the concave portion of the recess 43 is relatively high, and may deform during the production process due to local stress concentration, increasing the risk of abnormal concave deformation or even cracking of the explosion-proof valve 4. When the difference between the maximum dimension B between the protrusion 42 and the first surface 410 and the minimum dimension C between the recess 43 and the first surface 410 is too small, the protrusion 42 and the recess 43 may not be able to absorb and disperse the pressure in a timely and effective manner, thereby increasing the risk of the explosion-proof valve 4 becoming concave and convex, leading to cracking or premature valve opening. This application, by reasonably controlling the range of the difference between the maximum dimension B between the protrusion 42 and the first surface 410 in the thickness direction X and the minimum dimension C between the recess 43 and the first surface 410 in the thickness direction X, fully absorbs and disperses the stress brought to the explosion-proof valve 4 by the pressure difference between the cavity 10 and the shell 1 during the production of the single cell, avoids the problem of concave and convex deformation of the explosion-proof valve 4 due to local stress concentration, which could lead to cracking or premature valve opening. This can effectively improve the production yield of the single cell and improve the safety and reliability of the single cell.

[0052] In some embodiments, the maximum dimension of the support portion 40 in the thickness direction X is A mm, satisfying: C > A, 0.4 ≤ A ≤ 0.6. Exemplarily, the maximum dimension A of the support portion 40 can be any one of 0.4, 0.42, 0.44, 0.46, 0.48, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, or a range between any two. This configuration ensures the connection stability between the support portion 40 and the cover plate 3, preventing the explosion-proof valve 4 from loosening or falling off due to unstable connection during the single-cell manufacturing process or normal use, thus improving the safety and reliability of the single-cell battery. When the minimum dimension C between the recess 43 and the first surface 410 in the thickness direction X is less than the maximum dimension A of the support portion 40 in the thickness direction X, stress cannot be effectively distributed to the protrusion 42, and the explosion-proof valve 4 is at risk of inward concavity. In this embodiment, by limiting the minimum dimension C between the recess 43 and the first surface 410 in the thickness direction X to be greater than the maximum dimension A of the bearing portion 40 in the thickness direction X, the protrusion 42 and the recess 43 can effectively disperse stress and fully absorb and disperse the stress brought to the explosion-proof valve 4 by the pressure difference between the cavity 10 and the shell 1 during the production of a single cell. This avoids the problem of the explosion-proof valve 4 being concave in the middle and convex in the outside due to local stress concentration, which could lead to cracking or premature opening of the explosion-proof valve 4.

[0053] In some embodiments, a notch 411 is provided in the weak portion 41, and the notch 411 surrounds the protrusion 42. By providing the notch 411, the weak portion 41 can more accurately rupture at the notch 411 when subjected to a preset pressure, ensuring that the explosion-proof valve 4 releases the gas inside the single cell in a timely manner under appropriate pressure, thereby effectively reducing the internal pressure and preventing the single cell from becoming dangerous.

[0054] In some embodiments, the notch 411 may be provided on the side of the weak portion 41 away from the electrode assembly 2 and recessed towards the electrode assembly 2. In other embodiments, the notch 411 may be provided on the side of the weak portion 41 close to the electrode assembly 2 and recessed away from the electrode assembly 2. Specifically, in Figure 3 , Figure 5 In the illustrated embodiment, the groove 411 is provided on the side of the weak portion 41 away from the electrode assembly 2 and recessed towards the electrode assembly 2. The groove 411 can be formed by laser etching or by machining or other methods, and this application does not limit this.

[0055] exist Figure 2 and Figure 5In the illustrated embodiment, the support portion 40 is connected to the side of the cover plate 3 near the electrode assembly 2, and the protrusion 42 protrudes into the explosion-proof hole 30. Placing the explosion-proof valve 4 on the side of the cover plate 3 near the electrode assembly 2 avoids the problem of easy failure due to scratching that occurs when welding the explosion-proof valve 4 to the outer wall of the cover plate 3, thus ensuring the stability of the connection between the explosion-proof valve 4 and the cover plate 3.

[0056] exist Figure 2 and Figure 5 In the illustrated embodiment, a limiting groove 31 is formed on the side of the cover plate 3 near the electrode assembly 2. The limiting groove 31 surrounds the explosion-proof hole 30 and is located on the side of the cover plate 3 near the electrode assembly 2. The supporting part 40 is disposed within the limiting groove 31. The limiting groove 31 can position and fix the explosion-proof valve 4. By providing a limiting groove 31 on the cover plate 3 and placing the explosion-proof valve 4 within the limiting groove 31, the explosion-proof valve 4 will not occupy the space of the electrode assembly 2 in the receiving cavity 10, thereby improving the energy density and performance of the single battery cell.

[0057] This application provides a battery pack including the aforementioned individual battery cells. Therefore, the battery pack can possess all the technical features and beneficial effects of the aforementioned individual battery cells, which will not be repeated here. The battery pack also includes a housing, wherein at least one individual battery cell is housed inside the housing.

[0058] Accordingly, this application also provides an electrical device, including the aforementioned single battery cell, or the aforementioned battery pack. Therefore, the electrical device can possess all the technical features and beneficial effects of the aforementioned single battery cell or battery pack, which will not be elaborated upon here. The electrical device can be a mobile phone, portable device, laptop computer, electric vehicle, electric car, ship, spacecraft, electric toy, and power tool, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0059] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0060] The foregoing has provided a detailed description of a single battery, battery pack, and power device provided in the embodiments of this application, and specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A single-cell battery, characterized in that, include: A housing having a receiving cavity; An electrode assembly located within the receiving cavity; A cover plate, which is connected to the housing and seals the receiving cavity, and the cover plate is provided with explosion-proof holes; An explosion-proof valve, wherein the explosion-proof valve covers the explosion-proof hole, the explosion-proof valve includes a support portion, a weak portion, a protrusion and a recess connected in sequence from the outside to the inside, the support portion is connected to the cover plate, the weak portion is configured to be destroyed when subjected to a preset pressure impact, the protrusion protrudes from the connection with the weak portion toward the side away from the electrode assembly, and the recess is recessed toward the side closer to the electrode assembly; The area of ​​the protrusion is S1 mm. 2 The area of ​​the recess is S2 mm. 2 The area of ​​the explosion-proof valve is S mm. 2 The following conditions must be met: 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8, 0.35≤S1 / S≤0.6, 0.1≤S2 / S≤0.

2.

2. The single-cell battery according to claim 1, characterized in that, In the thickness direction of the cover plate, the weak portion includes a first surface close to the electrode assembly. In the thickness direction, the maximum dimension between the protrusion and the first surface is B mm, and the minimum dimension between the recess and the first surface is C mm, satisfying: 0.15≤BC≤0.

5.

3. The single-cell battery according to claim 2, characterized in that, The maximum dimension of the bearing part in the thickness direction is A mm, which satisfies: C>A, 0.4≤A≤0.

6.

4. The single-cell battery according to claim 1, characterized in that, The supporting part is connected to the side of the cover plate near the electrode assembly, and the protrusion protrudes into the explosion-proof hole.

5. The single-cell battery according to claim 1, characterized in that, A limiting groove is formed on the side of the cover plate near the electrode assembly. The limiting groove surrounds the explosion-proof hole. The limiting groove is formed on the side of the cover plate near the electrode assembly. The supporting part is disposed in the limiting groove.

6. A battery pack, characterized in that, Includes the single-cell battery as described in any one of claims 1 to 5.

7. An electrical device, characterized in that, It includes a single battery cell as described in any one of claims 1 to 5, or it includes a battery pack as described in claim 6.

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